Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. Sensor Device Data Book DL200/D Rev. 5, 01/2003 WWW.MOTOROLA.COM/SEMICONDUCTORS For More Information On This Product, Go to: www.freescale.com Freescale Semiconductor, Inc. DATA CLASSIFICATION Product Preview This heading on a data sheet indicates that the device is in the formative stages or in design (under development). The disclaimer at the bottom of the first page reads: "This document contains information on a product under development. Motorola reserves the right to change or discontinue this product without notice." Advance or Preliminary Information This heading on a data sheet indicates that the device is in sampling, preproduction, or first production stages. The disclaimer at the bottom of the first page reads: "This document contains information on a new product. Specifications and information herein are subject to change without notice." Freescale Semiconductor, Inc... Fully Released A fully released data sheet contains neither a classification heading nor a disclaimer at the bottom of the first page. This document contains information on a product in full production. Guaranteed limits will not be changed without written notice to your local Motorola Semiconductor Sales Office. MOTOROLA DEVICE CLASSIFICATIONS In an effort to provide up-to-date information to the customer regarding the status of any given device, Motorola has classified all devices into three categories: Preferred devices, Current products and Not Recommended for New Design products. A Preferred type is a device which is recommended as a first choice for future use. These devices are "preferred" by virtue of their performance, price, functionality, or combination of attributes which offer the overall "best" value to the customer. This category contains both advanced and mature devices which will remain available for the foreseeable future. Preferred devices in the Data Sheet sections are identified as a "Motorola Preferred Device.'' Device types identified as "current" may not be a first choice for new designs, but will continue to be available because of the popularity and/or standardization or volume usage in current production designs. These products can be acceptable for new designs but the preferred types are considered better alternatives for long term usage. Any device that has not been identified as a "preferred device" is a "current" device. Products designated as "Not Recommended for New Design" may become obsolete as dictated by poor market acceptance, or a technology or package that is reaching the end of its life cycle. Devices in this category have an uncertain future and do not represent a good selection for new device designs or long term usage. The Sensor Data Book does not contain any "Not Recommended for New Design" devices. ii For More Information On This Product, Go to: www.freescale.com Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Sensor Device Data Book The information in this book has been carefully reviewed and is believed to be accurate; however, no responsibility is assumed for inaccuracies. Furthermore, this information does not convey to the purchaser of semiconductor devices any license under the patent rights to the manufacturer. Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals", must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer. 5th Edition Motorola, Inc. 2003 "All Rights Reserved" Printed in U.S.A. iii On This Product, For More Information Go to: www.freescale.com Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. iv For More Information On This Product, Go to: www.freescale.com Freescale Semiconductor, Inc. TABLE OF CONTENTS SECTION ONE -- General Information Quality and Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Reliability Issues for Silicon Pressure Sensors . . . . . . 1-3 Soldering Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Pressure Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11 Electrostatic Process Control . . . . . . . . . . . . . . . . . . 1-17 Statistical Process Control . . . . . . . . . . . . . . . . . . . . . . 1-11 Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Accelerometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Freescale Semiconductor, Inc... Media Compatibility Overview . . . . . . . . . . . . . . . . . . . 1-18 SECTION TWO -- Acceleration Sensor Products Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Device Numbering System . . . . . . . . . . . . . . . . . . . . . . . 2-2 Sensor Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Acceleration Sensor FAQ's . . . . . . . . . . . . . . . . . . . . . . . 2-4 Data Sheets MMA1200D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 5 MMA1201P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 MMA1220D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 18 MMA1250D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24 MMA1260D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-30 MMA1270D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-36 MMA2201D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 42 MMA2202D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 48 MMA3201D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 55 Application Notes AN1559 Application Considerations for a Switched Capacitor Accelerometer . . . . . . . . . . . . . 2- 62 AN1611 Impact and Tilt Measurement Using Accelerometer . . . . . . . . . . . . . . . . . . 2-65 AN1612 Shock and Mute Pager Applications Using Accelerometer . . . . . . . . . . . . . . . . . . 2-77 AN1632 MMA1201P Product Overview and Interface Considerations . . . . . . . . . . 2- 84 AN1635 Baseball Pitch Speedometer . . . . . . . . . . . . 2- 89 AN1640 Reducing Accelerometer Susceptibility to BCI . . . . . . . . . . . . . . . . . 2-101 AN1925 Using the Motorola Accelerometer Evaluation Board . . . . . . . . . . . . . . . . . . . 2- 104 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-107 Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-109 SECTION THREE -- Pressure Sensor Products Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 Device Numbering System . . . . . . . . . . . . . . . . . . . . . . . 3-4 Package Offerings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Orderable Part Numbers . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 Pressure Sensor Overview General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 Motorola Pressure Sensors . . . . . . . . . . . . . . . . . . . . . . 3-8 Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 Sensor Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 Pressure Sensor FAQ's . . . . . . . . . . . . . . . . . . . . . . . . 3-14 Data Sheets MPX10, MPXV10GC Series . . . . . . . . . . . . . . . . . . . . 3-15 MPX12 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 MPX2010, MPXV2010G Series . . . . . . . . . . . . . . . . . 3-23 MPX2050 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 MPX2053, MPXV2053G Series . . . . . . . . . . . . . . . . . 3-31 MPX2100 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35 MPX2102, MPXV2102G Series . . . . . . . . . . . . . . . . . 3-39 MPX2200 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-43 MPX2202, MPXV2202G Series . . . . . . . . . . . . . . . . . 3-47 MPX2300DT1, MPX2301DT1 . . . . . . . . . . . . . . . . . . . 3-51 MPX4080D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-54 MPX4100 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-59 MPX4100A, MPXA4100A Series . . . . . . . . . . . . . . . . 3-64 MPX4101A MPXA4101A, MPXH6101A Series . . . . 3-70 MPX4105A Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-75 MPX4115A, MPXA4115A Series . . . . . . . . . . . . . . . . . 3-79 MPX4200A Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-84 MPX4250A, MPXA4250A Series . . . . . . . . . . . . . . . . 3-88 MPX4250D Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-93 MPX5010, MPXV5010G Series . . . . . . . . . . . . . . . . . 3-97 MPX5050, MPXV5050G Series . . . . . . . . . . . . . . . . 3-103 MPX5100 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-108 MPX53, MPXV53GC Series . . . . . . . . . . . . . . . . . . . 3-114 MPX5500 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-118 MPX5700 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-122 MPX5999D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-126 MPXA6115A, MPXH6115A . . . . . . . . . . . . . . . . . . . . 3-130 MPXAZ4100A Series . . . . . . . . . . . . . . . . . . . . . . . . . 3-135 MPXAZ4115A Series . . . . . . . . . . . . . . . . . . . . . . . . . 3-140 MPXAZ6115A Series . . . . . . . . . . . . . . . . . . . . . . . . . 3-145 MPXC2011DT1, MPXC2012DT1 . . . . . . . . . . . . . . . 3-150 MPXH6300A Series . . . . . . . . . . . . . . . . . . . . . . . . . . 3-153 MPXM2010 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-158 MPXM2053 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-161 MPXM2102 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-164 MPXM2202 Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-167 MPXV4006G Series . . . . . . . . . . . . . . . . . . . . . . . . . . 3-170 MPXV4115V Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-174 MPXV5004G Series . . . . . . . . . . . . . . . . . . . . . . . . . . 3-179 MPXV6115VC6U . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-183 Application Notes AN935 Compensating for Nonlinearity in the MPX10 Series Pressure Transducer . . . 3-188 AN936 Mounting Techniques, Lead Forming and Testing of Motorola's MPX Series MPX10 Series Pressure Sensors . . . . . . 3-195 AN1082 Simple Design for a 3-20 mA Transmitter Interface Using a Motorola Pressure Sensor . . . . . . . . . . . . . . . . . . . . 3-200 (continued -- next page) v On This Product, For More Information Go to: www.freescale.com Freescale Semiconductor, Inc. Table of Contents (continued) Freescale Semiconductor, Inc... SECTION THREE (continued) AN1097 Calibration-Free Pressure Sensor System . . . . . . . . . . . . . . . . . . . . . . AN1100 Analog to Digital Converter Resolution Extension Using a Motorola Pressure Sensor . . . . . . . . . . . . . . . . . . . . AN1303 A Simple 3-20 mA Pressure Transducer Evaluation Board . . . . . . . . . AN1304 Integrated Sensor Simplifies Bar Graph Pressure Gauge . . . . . . . . . . . . . . . AN1305 An Evaluation System for Direct Interface of the MPX5100 Pressure Sensor with a Microprocessor . . . . . . . . . AN1309 Compensated Sensor Bar Graph Pressure Gauge . . . . . . . . . . . . . . . . . . . . . AN1315 An Evaluation System Interfacing the MPX2000 Series Pressure Sensors to a Microprocessor . . . . . . . . . . . . . . . . . . AN1316 Frequency Output Conversion for MPX2000 Series Pressure Sensors . . . . AN1318 Interfacing Semiconductor Pressure Sensors to Microcomputers . . . . . . . . . . . AN1322 Applying Semiconductor Sensors to Bar Graph Pressure Gauges . . . . . . . . . . AN1325 Amplifiers for Semiconductor Pressure Sensors . . . . . . . . . . . . . . . . . . . AN1326 Barometric Pressure Measurement Using Semiconductor Pressure Sensors . . . . . . . . . . . . . . . . . . . AN1513 Mounting Techniques and Plumbing Options of Motorola's MPX Series Pressure Sensors . . . . . . . . . . . . . . . . . . . AN1516 Liquid Level Control Using a Motorola Pressure Sensor . . . . . . . . . . . . AN1517 Pressure Switch Design with Semiconductor Pressure Sensors . . . . . AN1518 Using a Pulse Width Modulated Output with Semiconductor Pressure Sensors . . . . . . . . . . . . . . . . . . . AN1525 The A-B-C's of Signal-Conditioning Amplifier Design for Sensor Applications . . . . . . . . . . . . . . . . . . AN1536 Digital Boat Speedometers . . . . . . . . . . . . . AN1551 Low Pressure Sensing with the MPX2010 Pressure Sensor . . . . . . . . . . . AN1556 Designing Sensor Performance Specifications for MCU-based Systems . . . . . . . . . . . . . . . . AN1571 Digital Blood Pressure Meter . . . . . . . . . . . . 3-203 3-208 3-211 3-214 3-219 3-235 3-242 AN1573 Understanding Pressure and Pressure Measurement . . . . . . . . . . . AN1586 Designing a Homemade Digital Output for Analog Voltage Output Sensors . . . . . AN1636 Implementing Auto Zero for Integrated Pressure Sensors . . . . . . . . . . AN1646 Noise Considerations for Integrated Pressure Sensors . . . . . . . . . . . . . . . . . . . AN1660 Compound Coefficient Pressure Sensor PSPICE Models . . . . . . . . . . . . . . . . . . . . . AN1668 Washing Appliance Sensor Selection . . . . . AN1950 Water Level Monitoring . . . . . . . . . . . . . . . . . AN4007 New Small Amplified Automotive Vacuum Sensors A Single Chip Sensor Solution for Brake Booster Monitoring . . . . . . . . . . AN4010 Low-Pressure Sensing Using MPX2010 Series Pressure Sensors . . . . 3-363 3-368 3-375 3-378 3-384 3-390 3-395 3-413 3-418 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-423 3-269 Reference Information Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-439 Mounting and Handling Suggestions . . . . . . . . . . . . 3-441 Standard Warranty Clause . . . . . . . . . . . . . . . . . . . . . 3-442 3-279 Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-443 3-263 Symbols, Terms, and Definitions . . . . . . . . . . . . . . . 3-446 3-284 SECTION FOUR -- Safety and Alarm Integrated Circuits 3-288 3-297 3-301 3-306 3-312 Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Data Sheets MC14467-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 3 MC14468 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 9 MC14578 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 15 MC14600 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19 MC145010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 24 MC145011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 34 MC145012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 44 MC145017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-54 MC145018 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 60 3-318 3-325 Application Notes AN1690 Alarm IC General Applications Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 66 AN4009 Alarm IC Sample Applications . . . . . . . . . . . . 4-70 3-337 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-72 3-346 3-355 SECTION FIVE -- Alphanumeric Device Index Alphanumeric Device Index . . . . . . . . . . . . . . . . . . . . . . 5-2 vi For More Information On This Product, Go to: www.freescale.com Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Section One General Information Quality and Reliability . . . . . . . . . . . . . . . . . . . . . . . 1-2 Introduction: This version of the Sensor Products Device Data Handbook is organized to provide easy reference to sensor device information. We have reorganized the book based upon your recommendations with our goal to make designing in pressure, acceleration and safety and alarm ICs easy, and if you do have a question, you will have access to the technical support you need. The handbook is organized by product line, acceleration, pressure and safety and alarm ICs. Once in a section, you will find a glossary of terms, a list of frequently asked questions or other relevant data. If you have recommendations for improvement, please complete the comment card and return it to us or, feel free to call our Sensor Device Data Handbook hot line and we will personally record your comments. The hot line number is 480/413-3333. We look forward to hearing from you! Motorola Sensor Device Data Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Reliability Issues for Silicon Pressure Sensors . . . . 1-3 Soldering Precautions . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Pressure Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11 Electrostatic Process Control . . . . . . . . . . . . . . . . 1-11 Statistical Process Control . . . . . . . . . . . . . . . . . . . . 1-13 Test Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Accelerometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Media Compatability Overview . . . . . . . . . . . . . 1-18 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-1 Freescale Semiconductor, Inc. Quality and Reliability -- Overview A Major Objective of the Production Cycle From rigid incoming inspection of piece parts and materials, to stringent outgoing quality verification, the Motorola assembly and process flow is encompassed by an elaborate system of test and inspection stations; stations to ensure a step-by-step adherence to prescribed procedure. This produces the high level of quality for which Motorola is known . . . from start to finish. As illustrated in the process flow overview, every major manufacturing step is followed by an appropriate in-process quality inspection to insure product conformance to specification. In addition, Statistical Process Control (S.P.C.) techniques are utilized on all critical processes to insure processing equipment is capable of producing the product to the target specification while minimizing the variability. Quality control in wafer processing, assembly, and final test impart Motorola sensor products with a level of reliability that easily exceeds almost all industrial, consumer, and military requirements. Freescale Semiconductor, Inc... Compensated Sensor Flow Chart BINNING CHECK LASER I.D. INITIAL OXIDATION 1 P+ PHOTO RESIST 2 RESISTOR PHOTO RESIST EMITTER PHOTO RESIST RESISTOR IMPLANT 6 5 THIN-FILM METAL DEP. 12 SAW AND WASH DIE SORT AND LOAD METAL PHOTO RESIST CLASS PROBE WAFER TO WAFER BOND 15 CELL MARKING DIE BOND AND CURE 17 LASER TRIM 20 1-2 16 WIREBOND 18 100% FUNCTIONAL TEST GEL FILL AND CURE 9 FRONT METAL 14 13 FINAL OXIDATION 11 WAFER FINAL VISUAL CAVITY ETCH 4 8 7 10 CAVITY PHOTO RESIST 3 EMITTER DIFFUSION CONTACT PHOTO RESIST THIN-FILM METAL P.R. P+ DIFFUSION FINAL VISUAL 21 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 19 PACK AND SHIP 22 23 Motorola Sensor Device Data Freescale Semiconductor, Inc. Reliability Issues for Silicon Pressure Sensors by Theresa Maudie and Bob Tucker Sensor Products Division Revised June 9, 1997 Freescale Semiconductor, Inc... ABSTRACT Reliability testing for silicon pressure sensors is of greater importance than ever before with the dramatic increase in sensor usage. This growth is seen in applications replacing mechanical systems, as well as new designs. Across all market segments, the expectation for the highest reliability exists. While sensor demand has grown across all of these segments, the substantial increase of sensing applications in the automotive arena is driving the need for improved reliability and test capability. The purpose of this paper is to take a closer look at these reliability issues for silicon pressure sensors. INTRODUCTION Discussing reliability as it pertains to semiconductor electronics is certainly not a new subject. However, when developing new technologies like sensors how reliability testing will be performed is not always obvious. Pressure sensors are an intriguing dilemma. Since they are electromechanical devices, different types of stresses should be considered to insure the different elements are exercised as they would be in an actual application. In addition, the very different package outlines relative to other standard semiconductor packages require special fixtures and test set-ups. However, as the sensor marketplace continues to grow, reliability testing becomes more important than ever to insure that products being used across all market segments will meet reliability lifetime expectations. RELIABILITY DEFINITION Reliability is [1] the probability of a product performing its intended function over its intended lifetime and under the operating conditions encountered. The four key elements of the definition are probability, performance, lifetime, and operating conditions. Probability implies that the reliability lifetime estimates will be made based on statistical techniques where samples are tested to predict the lifetime of the manufactured products. Performance is a key in that the sample predicts the performance of the product at a given point in time but the variability in manufacturing must be controlled so that all devices perform to the same functional level. Lifetime is the period of time over which the product is intended to perform. This lifetime could be as small as one week in the case of a disposable blood pressure transducer or as long as 15 years for automotive applications. Environment is the area that also plays a key role since the operating conditions of the product can greatly influence the reliability of the product. Environmental factors that can be seen during the lifetime of any semiconductor product include temperature, humidity, electric field, magnetic field, current density, pressure differential, vibration, and/or a chemical interaction. Reliability testing is generally formulated to take into account all of these potential factors either individually or in multiple Motorola Sensor Device Data combinations. Once the testing has been completed predictions can be made for the intended product customer base. If a failure would be detected during reliability testing, the cause of the failure can be categorized into one of the following: design, manufacturing, materials, or user. The possible impact on the improvements that may need to be made for a product is influenced by the stage of product development. If a product undergoes reliability testing early in its development phase, the corrective action process can generally occur in an expedient manner and at minimum cost. This would be true whether the cause of failure was attributed to the design, manufacturing, or materials. If a reliability failure is detected once the product is in full production, changes can be very difficult to make and generally are very costly. This scenario would sometimes result in a total redesign. The potential cause for a reliability failure can also be user induced. This is generally the area that the least information is known, especially for a commodity type manufacturer that achieves sales through a global distribution network. It is the task of the reliability engineer to best anticipate the multitudes of environments that a particular product might see, and determine the robustness of the product by measuring the reliability lifetime parameters. The areas of design, manufacturing, and materials are generally well understood by the reliability engineer, but without the correct environmental usage, customer satisfaction can suffer from lack of optimization. RELIABILITY STATISTICS Without standardization of the semiconductor sensor standards, the end customer is placed in a situation of possible jeopardy. If non-standard reliability data is generated and published by manufacturers, the information can be perplexing to disseminate and compare. Reliability lifetime statistics can be confusing for the novice user of the information, "let the buyer beware". The reporting of reliability statistics is generally in terms of failure rate, measured in FITs, or failure rate for one billion device hours. In most cases, the underlying assumption used in reporting either the failure rate or the MTBF is that the failures occurring during the reliability test follow an exponential life distribution. The inverse of the failure rate is the MTBF, or mean time between failure. The details on the various life distributions will not be explored here but the key concern about the exponential distribution is that the failure rate over time is constant. Other life distributions, such as the lognormal or Weibull can take on different failure rates over time, in particular, both distributions can represent a wear out or increasing failure rate that might be seen on a product reaching the limitations on its lifetime or for certain types of failure mechanisms. The time duration use for the prediction of most reliability statistics is of relatively short duration with respect to the product's lifetime ability and failures are usually not observed. When a test is terminated after a set number of hours is achieved, or time censored, and no failures are observed, the failure rate can be estimated by use of the chisquare distribution which relates observed and expected www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-3 Freescale Semiconductor, Inc. new product and they have put a total of 1,000 parts on a high temperature storage test for 500 hours each, their corresponding cumulative device hours would be 500,000 device hours. Vendor B has been in the business for several years on the same product and has tested a total of 500,000 parts for 10 hours each to the same conditions as part of an in-line burn-in test for a total of 5,000,000 device hours. The corresponding failure rate for a 60% confidence level for vendor A would be 1,833 FITs, vendor B would have a FIT rate of 183 FITs. frequencies of an event to established confidence intervals. The relationship between failure rate and the chi-square distribution is as follows: lL1 2 + x a2t, d.f. Where: = = = = = = = failure rate lower one side confidence limit chi-square function risk, (1-confidence level) degrees of freedom = 2 (r + 1) number of failures device hours Table 1. Chi-Square Table Chi-Square Distribution Function 60% Confidence Level Chi-square values for 60% and 90% confidence intervals for up to 12 failures is shown in Table 1. As indicated by the table, when no failures occur, an estimate for the chi-square distribution interval is obtainable. This interval estimate can then be used to solve for the failure rate, as shown in the equation above. If no failures occur, the failure rate estimate is solely a function of the accumulated device hours. This estimate can vary dramatically as additional device hours are accumulated. As a means of showing the influence of device hours with no failures on the failure rate value, a graphical representation of cumulative device hours versus the failure rate measured in FITs is shown in Figure 1. A descriptive example between two potential vendors best serves to demonstrate the point. If vendor A is introducing a 90% Confidence Level No. Fails 2 Quantity No. Fails 2 Quantity 0 1.833 0 4.605 1 4.045 1 7.779 2 6.211 2 10.645 3 8.351 3 13.362 4 10.473 4 15.987 5 12.584 5 18.549 6 14.685 6 21.064 7 16.780 7 23.542 8 18.868 8 25.989 9 20.951 9 28.412 10 23.031 10 30.813 11 25.106 11 33.196 12 27.179 12 35.563 109 108 107 FAILURE RATE, [FITs] Freescale Semiconductor, Inc... L1 2 d.f. r t 106 105 104 1,000 100 10 1 0.1 1 10 100 1,000 104 105 106 107 108 109 CUMULATIVE DEVICE HOURS, [t] Figure 1. Depiction of the influence on the cumulative device hours with no failures and the Failure Rate as measured in FITs. 1-4 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. One could thus imply that the reliability performance indicates that vendor B has an order of magnitude improvement in performance over vendor A with neither one seeing an occurrence of failure during their performance. The incorrect assumption of a constant failure rate over time can potentially result in a less reliable device being designed into an application. The reliability testing assumptions and test methodology between the various vendors needs to be critiqued to insure a full understanding of the product performance over the intended lifetime, especially in the case of a new product. Testing to failure and determination of the lifetime statistics is beyond the scope of this paper and presented elsewhere [2]. Freescale Semiconductor, Inc... INDUSTRY RELIABILITY STANDARDS Reliability standards for large market segments are often developed by "cross-corporation" committees that evaluate the requirements for the particular application of interest. It is the role of these committees to generate documents intended as guides for technical personnel of the end users and suppliers, to assist with the following functions: specifying, developing, demonstrating, calibrating, and testing the performance characteristics for the specific application. One such committee which has developed a standard for a particular application is the Blood Pressure Monitoring Committee of the Association for the Advancement of Medical Instrumentation (AAMI) [3]. Their document, the "American National Standard for Interchangeability and Performance of Resistive Bridge Type Blood Pressure Transducers", has an objective to provide performance requirements, test methodology, and terminology that will help insure that safe, accurate blood pressure transducers are supplied to the marketplace. In the automotive arena, the Society of Automotive Engineers (SAE) develops standards for various pressure sensor applications such as SAE document J1346, "Guide to Manifold Absolute Pressure Transducer Representative Test Method" [4]. While these two very distinct groups have successfully developed the requirements for their solid-state silicon pressure sensor needs, no real standard has been set for the general industrial marketplace to insure products being offered have been tested to insure reliability under industrial conditions. Motorola has utilized MIL-STD-750 as a reference document in establishing reliability testing practices for the silicon pressure sensor, but the differences in the technology between a discrete semiconductor and a silicon pressure sensor varies dramatically. The additional tests that are utilized in semiconductor sensor reliability testing are based on the worst case operational conditions that the device might encounter in actual usage. ESTABLISHED SENSOR TESTING Motorola has established semiconductor sensor reliability testing based on exercising to detect failures by the presence of the environmental stress. Potential failure modes and causes are developed by allowing tests to run beyond the normal test times, thus stressing to destruction. The typical reliability test matrix used to insure conformance to customers end usage is as follows [5]: Motorola Sensor Device Data PULSED PRESSURE TEMPERATURE CYCLING WITH BIAS (PPTCB) This test is an environmental stress test combined with cyclic pressure loading in which the devices are alternately subjected to a low and high temperature while operating under bias under a cyclical pressure load. This test simulates the extremes in the operational life of a pressure sensor. PPTCB evaluates the sensor's overall performance as well as evaluating the die, die bond, wire bond and package integrity. Typical Test Conditions: Temperature per specified operating limits (i.e., Ta = -40 to 125C for an automotive application). Dwell time 15 minutes, transfer time 5 minutes, bias = 100% rated voltage. Pressure = 0 to full scale, pressure frequency = 0.05 Hz, test time = up to 1000 hours. Potential Failure Modes: Open, short, parametric shift. Potential Failure Mechanisms: Die defects, wire bond fatigue, die bond fatigue, port adhesive failure, volumetric gel changes resulting in excessive package stress. Mechanical creep of packaging material. HIGH HUMIDITY, HIGH TEMPERATURE WITH BIAS (H3TB) A combined environmental/electrical stress test in which devices are subjected to an elevated ambient temperature and humidity while under bias. The test is useful for evaluating package integrity as well as detecting surface contamination and processing flaws. Typical Test Conditions: Temperature between 60 and 85C, relative humidity between 85 and 90%, rated voltage, test time = up to 1000 hours. Potential Failure Modes: Open, short, parametric shift. Potential Failure Mechanisms: Shift from ionic affect, parametric instability, moisture ingress resulting in excessive package stress, corrosion. HIGH TEMPERATURE WITH BIAS (HTB) This operational test exposes the pressure sensor to a high temperature ambient environment in which the device is biased to the rated voltage. The test is useful for evaluating the integrity of the interfaces on the die and thin film stability. Typical Test Conditions: Temperature per specified operational maximum, bias = 100% rated voltage, test time = up to 1000 hours. Potential Failure Modes: Parametric shift in offset and/or sensitivity. Potential Failure Mechanisms: Bulk die or diffusion defects, film stability and ionic contamination. HIGH AND LOW TEMPERATURE STORAGE LIFE (HTSL, LTSL) High and low temperature storage life testing is performed to simulate the potential shipping and storage conditions that the pressure sensor might encounter in actual usage. The test also evaluates the devices thermal integrity at worst case temperatures. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-5 Freescale Semiconductor, Inc. Typical Test Conditions: Temperature per specified storage maximum and minimum, no bias, test time = up to 1000 hours. Potential Failure Modes: Parametric shift in offset and/or sensitivity. Potential Failure Mechanisms: Bulk die or diffusion defects, mechanical creep in packaging components due to thermal mismatch. Freescale Semiconductor, Inc... TEMPERATURE CYCLING (TC) This is an environmental test in which the pressure sensor is alternatively subjected to hot and cold temperature extremes with a short stabilization time at each temperature in an air medium. The test will stress the devices by generating thermal mismatches between materials. Typical Test Conditions: Temperature per specified storage maximum and minimum (i.e., -40 to +125C for automotive applications). Dwell time 15 minutes, transfer time 5 minutes, no bias. Test time up to 1000 cycles. Potential Failure Modes: Open, parametric shift in offset and/or sensitivity. Potential Failure Mechanisms: Wire bond fatigue, die bond fatigue, port adhesive failure, volumetric gel changes resulting in excessive package stress. Mechanical creep of packaging material. MECHANICAL SHOCK This is an environmental test where the sensor device is evaluated to determine its ability to withstand a sudden change in mechanical stress due to an abrupt change in motion. This test simulates motion that may be seen in handling, shipping or actual use. MIL STD 750, Method 2016 Reference. Typical Test Conditions: Acceleration = 1500 g's, orientation = X, Y, Z planes, time = 0.5 milliseconds, 5 blows. Potential Failure Modes: Open, parametric shift in offset and/or sensitivity. Potential Failure Mechanisms: Diaphragm fracture, mechanical failure of wire bonds or package. VARIABLE FREQUENCY VIBRATION A test to examine the ability of the pressure sensor device to withstand deterioration due to mechanical resonance. MIL STD 750, Method 2056 Reference. Typical Test Conditions: Frequency - 10 Hz to 2 kHz, 6.0 G's max, orientation = X, Y, Z planes, 8 cycles each axis, 2 hrs. per cycle. Potential Failure Modes: Open, parametric shift in offset and/or sensitivity. Potential Failure Mechanisms: Diaphragm fracture, mechanical failure of wire bonds or package. SOLDERABILITY In this reliability test, the lead/terminals are evaluated for their ability to solder after an extended time period of storage (shelf life). MIL STD 750, Method 2026 Reference. 1-6 Typical Test Conditions: Steam aging = 8 hours, Flux= R, Solder = Sn63, Pb37. Potential Failure Modes: Pin holes, non-wetting, dewetting. Potential Failure Mechanisms: Poor plating, contamination. OVER PRESSURE This test is performed to measure the ability of the pressure sensor to withstand excessive pressures that may be encountered in the application. The test is performed from either the front or back side depending on the application. Typical Test Conditions: Pressure increase to failure, record value. Potential Failure Modes: Open. Potential Failure Mechanisms: Diaphragm fracture, adhesive or cohesive failure of die attach. A pressure sensor may be placed in an application where it will be exposed to various media that may chemically attack the active circuitry, silicon, interconnections and/or packaging material. The focus of media compatibility is to understand the chemical impact with the other environmental factors such as temperature and bias and determine the impact on the device lifetime. The primary driving mechanism to consider is permeation which quantifies the time for a chemical to permeate across a membrane or encapsulant corrosion can result. Media related product testing is generally very specific to the application since the factors that relate to the product lifetime are very numerous and varied. An example is solution pH where the further from neutral will drive the chemical reaction, generally to a power rule relationship. The pH alone does not always drive the reaction either, the non-desired products in the media such as strong acids in fuels as a result of acid rain can directly influence the lifetime. It is recommended the customer and/or vendor perform application specific testing that best represents the environment. This testing should be performed utilizing in situ monitoring of the critical device parameter to insure the device survives while exposed to the chemical. The Sensor Products Division within Motorola has a wide range of media specific test capabilities and under certain circumstances will perform application specific media testing. A sufficient sample size manufactured over a pre-defined time interval to maximize process and time variability is tested based on the guidelines of the matrix shown above. This test methodology is employed on all new product introductions and process changes on current products. A silicon pressure sensor has a typical usage environment of pressure, temperature, and voltage. Unlike the typical bipolar transistor life tests which incorporate current density and temperature to accelerate failures, a silicon pressure sensor's acceleration of its lifetime performance is primarily based on the pressure and temperature interaction with a presence of bias. This rationale was incorporated into the development of the Pulsed Pressure Temperature Cycling with Bias (PPTCB) test where the major acceleration factor is the pressure and temperature component. It is also why PPTCB is considered the standard sensor operational life test. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. To insure that silicon pressure sensors are designed and manufactured for reliability, an in-depth insight into what mechanisms cause particular failures is required. It is safe to say that unless a manufacturer has a clear understanding of everything that can go wrong with the device, it cannot design a device for the highest reliability. Figure 2 provides a look into the sensor operating concerns for a variety of potential usage applications. This information is utilized when developing the Failure Mode and Effects Analysis (FMEA). The FMEA then serves as the documentation that demonstrates all design and process concerns have been addressed to offer the most reliable approach. By understanding how to design products, control processes, and eliminate the concerns raised, a reliable product is achieved. ACCELERATED LIFE TESTING Freescale Semiconductor, Inc... It is very difficult to assess the reliability statistics for a product when very few or no failures occur. With cost as a predominant factor in any industrial setting and time of the utmost importance, the reliability test must be optimized. Optimization of reliability testing will allow the maximum amount of information on the product being tested to be gained in a minimum amount of time, this is accomplished by using accelerated life testing techniques. A key underlying assumption in the usage of accelerated life testing to estimate the life of a product at a lower or nominal stress is that the failure mechanism encountered at the high stress is the same as that encountered at the nominal stress. The most frequently applied accelerated environmental stress for semiconductors is temperature, it will be briefly explained here for its utilization in determining the lifetime reliability statistics for silicon pressure sensors. SENSOR RELIABILITY CONCERNS GEL: Viscosity Thermal Coefficient of Expansion Permeability (Diffusion x Solubility) Changes in Material or Process Height Coverage Uniformity Adhesive Properties Media Compatibility Gel Aeration Compressibility PACKAGE: Integrity Plating Quality Dimensions Thermal Resistance Mechanical Resistance Pressure Resistance Media Compatibility EEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEE AAAAAAAAAA EEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEE EEEEEEEEEEEEEEEEE BONDING WIRES: Strength Placement Height and Loop Size Material Bimetallic Contamination (Kirkendall Voids) Nicking and other damage General Quality & Workmanship LEADS: Materials and Finish Plating Integrity Solderability General Quality Strength Contamination Corrosion Adhesion MARKING: Permanency Clarity DIE ATTACH: Uniformity Resistance to Mechanical Stress Resistance to Temperature Stress Wetting Adhesive Strength Cohesive Strength Process Controls Die Orientation Die Height Change in Material or Process Media Compatibility Compressibility DIE METALLIZATION: Lifting or Peeling Alignment Scratches Voids Laser Trimming Thickness Step Coverage Contact Resistance Integrity DIAPHRAGM: Size Thickness Uniformity Pits Alignment Fracture PASSIVATION: Thickness Mechanical Defects Integrity Uniformity ELECTRICAL PERFORMANCE: Continuity and Shorts Parametric Stability Parametric Performance Temperature Performance Temperature Stability Long Term Reliability Storage Degradation Susceptibility to Radiation Damage Design Quality DESIGN CHANGES MATERIAL OR PROCESS CHANGES FAB & ASSEMBLY CLEANLINESS SURFACE CONTAMINATION FOREIGN MATERIAL SCRIBE DEFECTS DIFFUSION DEFECTS OXIDE DEFECTS Figure 2. Process and Product Variability Concerns During Reliability Testing Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-7 Freescale Semiconductor, Inc. The temperature acceleration factor for a particular failure mechanism can be related by taking the ratio for the reaction rate of the two different stress levels as expressed by the Arrhenius type of equation. The mathematical derivation of the first order chemical reaction rate computes to: (RT)HS tHS AF tLS (RT)LS + Freescale Semiconductor, Inc... AF Where: AF RT t T Ea = = = = = k LS HS = = = + exp + * Ea k 1 TLS 1 THS Acceleration Factor Reaction Rate time temperature [K] activation energy of expressed in electron-volts [eV] Boltzman's constant, 8.6171 x 10-5 eV/K Low stress or nominal temperature High stress or test temperature The activation energy is dependent on the failure mechanism and typically varies from 0.3 to 1.8 electron-volts. The activation energy is directly proportional to the degree of influence that temperature has on the chemical reaction rate. A listing of typical activation energies is included in reference [6] and [7]. An example using the Arrenhius equation will be demonstrated. A 32 device HTB test for 500 hours total and no failure was performed. The 125C, 100% rated voltage test resulted in no failures. If a customer 's actual usage conditions was 55C at full rated voltage, an estimate of the lower one side confidence limit can be calculated. An assumption is made that the failure rate is constant thus implying the exponential distribution. The first step is to calculate the equivalent device hours for the customer's use conditions by solving for the acceleration factor. From the acceleration factor above, if eA is assumed equal to 1, AF 1-8 + exp * Ea k 1 TLS 1 THS Where: eA TLS THS then; AF = = = 0.7eV/K (assumed) 55C + 273.16 = 328.16K 125C + 273.16 = 398.16K = 77.64 Therefore, the equivalent cumulative device hours at the customer's use condition is: tLS = AF x tHS = (32 500) 77.64 or tLS = 1,242,172 device hours Computing the lower one sided failure rate with a 90% confidence level and no failures: x2 (a, d.f.) l 2t or = 1.853E-06 failures per hour or = 1,853 FITs + The inverse of the failure, , or the Mean Time To Failure (MTTF) is: 1 MTTF l or MTTF = 540,000 device hours + CONCLUSION Reliability testing durations and acceptance numbers are used as a baseline for achieving adequate performance in the actual use condition that the silicon pressure sensor might encounter. The baseline for reliability testing can be related to the current record high jump bar height. Just as athletes in time achieve a higher level of performance by improvements in their level of physical and mental fitness, silicon pressure sensors must also incorporate improvements in the design, materials, and manufacturability to achieve the reliability growth demands the future market place will require. This philosophy of never ending improvement will promote consistent conformance to the customer's expectation and production of a best in class product. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. REFERENCES [4] "Interchangeability and Performance of Resistive Bridge Type Blood Pressure Transducers," AAMI Guideline, Blood Pressure Monitoring Committee, latest revision. [5] "Motorola D.M.T.G. Reliability Audit Report," Q191. [6] Wayne Nelson, "Accelerated Testing: Statistical Models," Test Plans, and Data Analyses, John Wiley & Sons, Inc., New York, N.Y., 1990. [7] D.S. Peck and O.D. Trapp, (1978), "Accelerated Testing Handbook," Technology Associates, revised 1987. Freescale Semiconductor, Inc... [1] Dr. Joseph E. Matar and Theresa Maudie, "Reliability Engineering and Accelerated Life Testing," Motorola Internal Training Text, 1989. [2] D.J. Monk, T. Maudie, D. Stanerson, J. Wertz, G. Bitko, J. Matkin, and S. Petrovic, "Media Compatible Packaging and Environmental Testing of Barrier Coating Encapsulated Silicon Pressure Sensors,'' 1996, Solid-State Sensors and Actuators Workshop. Hilton Head, SC, pp. 36-41, 1996. [3] "Guide to Manifold Absolute Pressure Transducer Representative Test Method," SAE Guideline J1346, Transducer Subcommittee, latest revision. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-9 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... SOLDERING PRECAUTIONS The melting temperature of solder is higher than the rated temperature of the device. When the entire device is heated to a high temperature, failure to complete soldering within a short time could result in device failure. Therefore, the following items should always be observed in order to minimize the thermal stress to which the devices are subjected. * Always preheat the device. * The delta temperature between the preheat and soldering should be 100C or less.* * For pressure sensor devices, a no-clean solder is recommended unless the silicone die coat is sealed and unexposed. Also, prolonged exposure to fumes can damage the silicone die coat of the device during the solder reflow process. * When preheating and soldering, the temperature of the leads and the case must not exceed the maximum temperature ratings as shown on the data sheet. When * * * * using infrared heating with the reflow soldering method, the difference should be a maximum of 10C. The soldering temperature and time should not exceed 260C for more than 10 seconds. When shifting from preheating to soldering, the maximum temperature gradient shall be 5C or less. After soldering has been completed, the device should be allowed to cool naturally for at least three minutes. Gradual cooling should be used since the use of forced cooling will increase the temperature gradient and will result in latent failure due to mechanical stress. Mechanical stress or shock should not be applied during cooling. * Soldering a device without preheating can cause excessive thermal shock and stress which can result in damage to the device. TYPICAL SOLDER HEATING PROFILE For any given circuit board, there will be a group of control settings that will give the desired heat pattern. The operator must set temperatures for several heating zones and a figure for belt speed. Taken together, these control settings make up a heating "profile" for that particular circuit board. On machines controlled by a computer, the computer remembers these profiles from one operating session to the next. Figure 3 shows a typical heating profile for use when soldering a surface mount device to a printed circuit board. This profile will vary among soldering systems, but it is a good starting point. Factors that can affect the profile include the type of soldering system in use, density and types of components on the board, type of solder used, and the type of board or substrate material being used. This profile shows temperature versus time. The line on the graph shows the STEP 1 PREHEAT ZONE 1 "RAMP" 200C STEP 2 STEP 3 VENT HEATING "SOAK" ZONES 2 & 5 "RAMP" DESIRED CURVE FOR HIGH MASS ASSEMBLIES actual temperature that might be experienced on the surface of a test board at or near a central solder joint. The two profiles are based on a high density and a low density board. The Vitronics SMD310 convection/infrared reflow soldering system was used to generate this profile. The type of solder used was 62/36/2 Tin Lead Silver with a melting point between 177 -189C. When this type of furnace is used for solder reflow work, the circuit boards and solder joints tend to heat first. The components on the board are then heated by conduction. The circuit board, because it has a large surface area, absorbs the thermal energy more efficiently, then distributes this energy to the components. Because of this effect, the main body of a component may be up to 30 degrees cooler than the adjacent solder joints. STEP 4 HEATING ZONES 3 & 6 "SOAK" STEP 5 HEATING ZONES 4 & 7 "SPIKE" STEP 6 VENT STEP 7 COOLING 205 TO 219C PEAK AT SOLDER JOINT 170C 160C 150C 150C 100C 140C 100C SOLDER IS LIQUID FOR 40 TO 80 SECONDS (DEPENDING ON MASS OF ASSEMBLY) DESIRED CURVE FOR LOW MASS ASSEMBLIES 50C TIME (3 TO 7 MINUTES TOTAL) TMAX Figure 3. Typical Solder Heating Profile 1-10 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Electrostatic Discharge Data Electrostatic damage (ESD) to semiconductor devices has plagued the industry for years. Special packaging and handling techniques have been developed to protect these sensitive devices. While many of Motorola's semiconductors devices are not susceptible to ESD, all products are revered as sensitive and handled accordingly. The data in this section was developed using the human-body model specified in MIL-STD-750C, Method 1020. The threshold values (Eth, kV) of ten devices was recorded, then the average value calculated. This data plus the device type, device source, package type, classification, polarity and general device description are supplied. Devices listed are mainly JEDEC registered 1N and 2N numbers. Military QPL devices and some customer specials are also in this database. The data in this report will be updated regularly, and the range will be added as new data becomes available. The sensitivity classifications listed are as follows: Class 1 . . .1 to 1999 volts The code "N/S" signifies a non-sensitive device. "SEN" are considered sensitive and should be handled according to ESD procedures. Of the various products manufactured by the Communications, Power and Signal Technologies Group, the following examples list general device families by not sensitive to extremely sensitive. Not sensitive . . . . . . FET current regulators Least sensitive . . . . Zener diodes (on a square mil/millijoule basis) Less sensitive . . . . . Bipolar transistors More sensitive . . . . Bipolar darlington transistors Very sensitive . . . . . Power TMOS devices Extremely sensitive Hot carrier diodes and MOSFET transistors without gate protection The data supplied herein, is listed in numerical or alphabetical order. Class 2 . . .2000 to 3999 volts DEVICE Class 3 . . .4000 to > 15500 volts LINE CASE CLASS PRODUCT DESCRIPTION MPX10D XL0010V1 344-15 3-SEN Uncompensated MPX10DP XL0010V1 344C-01 3-SEN Uncompensated MPX10GP XL0010V1 344B-01 3-SEN Uncompensated MPX12D XL0012V1 344-15 3-SEN Uncompensated MPX12DP XL0012V1 344C-01 3-SEN Uncompensated MPX12GP XL0012V1 344B-01 3-SEN Uncompensated MPX2010D XL2010V5 344-15 1-SEN Temperature Compensated/Calibrated MPX2010DP XL2010V5 344C-01 1-SEN Temperature Compensated/Calibrated MPX2010GP XL2010V5 344B-01 1-SEN Temperature Compensated/Calibrated MPX2010GS XL2010V5 344E-01 1-SEN Temperature Compensated/Calibrated MPX2010GSX XL2010V5 344F-01 1-SEN Temperature Compensated/Calibrated MPX2300DT1 XL2300C1,01C1 423-05 1-SEN Temperature Compensated/Calibrated MPX4100A XL4101S2 867-08 1-SEN Signal-Conditioned MPX4100AP XL4101S2 867B-04 1-SEN Signal-Conditioned MPX4100AS XL4101S2 867E-03 1-SEN Signal-Conditioned MPX4101A XL4101S2 867-08 1-SEN Signal-Conditioned MPX4115A XL4101S2 867-08 1-SEN Signal-Conditioned MPX4115AP XL4101S2 867B-04 1-SEN Signal-Conditioned MPX4115AS XL4101S2 867E-03 1-SEN Signal-Conditioned MPX4250A XL4101S2 867-08 1-SEN Signal-Conditioned MPX4250AP XL4101S2 867B-04 1-SEN Signal-Conditioned MPX5010D XL4010S5 867-08 1-SEN Signal-Conditioned MPX5010DP XL4010S5 867C-05 1-SEN Signal-Conditioned MPX5010GP XL4010S5 867B-04 1-SEN Signal-Conditioned MPX5010GS XL4010S5 867E-03 1-SEN Signal-Conditioned MPX5010GSX XL4010S5 867F-03 1-SEN Signal-Conditioned Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-11 Freescale Semiconductor, Inc. DEVICE LINE CASE CLASS PRODUCT DESCRIPTION XL4051S1 867-08 1-SEN Signal-Conditioned MPX5050DP XL4051S1 867C-05 1-SEN Signal-Conditioned MPX5050GP XL4051S1 867B-04 1-SEN Signal-Conditioned MPX5100D XL4101S1 867-08 1-SEN Signal-Conditioned MPX5100DP XL4101S1 867C-05 1-SEN Signal-Conditioned MPX5100GP XL4101S1 867B-04 1-SEN Signal-Conditioned MPX5700D XL4701S1 867-08 1-SEN Signal-Conditioned MPX5700DP XL4701S1 867C-05 1-SEN Signal-Conditioned MPX5700GP XL4701S1 867B-04 1-SEN Signal-Conditioned MPX5999D XL4999S1 867-08 1-SEN Signal-Conditioned Freescale Semiconductor, Inc... MPX5050D 1-12 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Statistical Process Control Motorola's Semiconductor Products Sector is continually pursuing new ways to improve product quality. Initial design improvement is one method that can be used to produce a superior product. Equally important to outgoing product quality is the ability to produce product that consistently conforms to specification. Process variability is the basic enemy of semiconductor manufacturing since it leads to product variability. Used in all phases of Motorola's product manufacturing, STATISTICAL PROCESS CONTROL (SPC) replaces variability with predictability. The traditional philosophy in the semiconductor industry has been adherence to the data sheet specification. Using SPC methods assures the product will meet specific process requirements throughout the manufacturing cycle. The emphasis is on defect prevention, not detection. Predictability through SPC methods requires the manufacturing culture to focus on constant and permanent improvements. Usually these improvements cannot be bought with state-of-the-art equipment or automated factories. With quality in design, process and material selection, coupled with manufacturing predictability, Motorola produces world class products. The immediate effect of SPC manufacturing is predictability through process controls. Product centered and distributed well within the product specification benefits Motorola with fewer rejects, improved yields and lower cost. The direct benefit to Motorola's customers includes better incoming quality levels, less inspection time and ship-tostock capability. Circuit performance is often dependent on the cumulative effect of component variability. Tightly controlled component distributions give the customer greater circuit predictability. Many customers are also converting to just-in-time (JIT) delivery programs. These programs require improvements in cycle time and yield predictability achievable only through SPC techniques. The benefit derived from SPC helps the manufacturer meet the customer's expectations of higher quality and lower cost product. Ultimately, Motorola will have Six Sigma capability on all products. This means parametric distributions will be centered within the specification limits with a product distribution of plus or minus Six Sigma about mean. Six Sigma capability, shown graphically in Figure 1, details the benefit in terms of yield and outgoing quality levels. This compares a centered distribution versus a 1.5 sigma worst case distribution shift. New product development at Motorola requires more robust design features that make them less sensitive to minor variations in processing. These features make the implementation of SPC much easier. A complete commitment to SPC is present throughout Motorola. All managers, engineers, production operators, supervisors and maintenance personnel have received multiple training courses on SPC techniques. Manufacturing has identified 22 wafer processing and 8 assembly steps considered critical to the processing of semiconductor products. Processes, controlled by SPC methods, that have shown significant improvement are in the diffusion, photolithography and metallization areas. Motorola Sensor Device Data -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 Standard Deviations From Mean Distribution Centered At 3 2700 ppm defective 99.73% yield At 4 63 ppm defective 99.9937% yield At 5 0.57 ppm defective 99.999943% yield At 6 0.002 ppm defective 99.9999998% yield Distribution Shifted 1.5 66810 ppm defective 93.32% yield 6210 ppm defective 99.379% yield 233 ppm defective 99.9767% yield 3.4 ppm defective 99.99966% yield Figure 1. AOQL and Yield from a Normal Distribution of Product With 6 Capability To better understand SPC principles, brief explanations have been provided. These cover process capability, implementation and use. PROCESS CAPABILITY One goal of SPC is to ensure a process is CAPABLE. Process capability is the measurement of a process to produce products consistently to specification requirements. The purpose of a process capability study is to separate the inherent RANDOM VARIABILITY from ASSIGNABLE CAUSES. Once completed, steps are taken to identify and eliminate the most significant assignable causes. Random variability is generally present in the system and does not fluctuate. Sometimes, these are considered basic limitations associated with the machinery, materials, personnel skills or manufacturing methods. Assignable cause inconsistencies relate to time variations in yield, performance or reliability. Traditionally, assignable causes appear to be random due to the lack of close examination or analysis. Figure 2 shows the impact on predictability that assignable cause can have. Figure 3 shows the difference between process control and process capability. A process capability study involves taking periodic samples from the process under controlled conditions. The performance characteristics of these samples are charted against time. In time, assignable causes can be identified and engineered out. Careful documentation of the process is key to accurate diagnosis and successful removal of the assignable causes. Sometimes, the assignable causes will remain unclear requiring prolonged experimentation. Elements which measure process variation control and capability are Cp and Cpk respectively. Cp is the specification width divided by the process width or Cp = (specification width) / 6. Cpk is the absolute value of the closest specification value to the mean, minus the mean, divided by half the process width or Cpk = | closest specification - X /3 . www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-13 Freescale Semiconductor, Inc. PREDICTION In control assignable causes eliminated TIME TIME Out of control (assignable causes present) SIZE Process "under control" - all assignable causes are removed and future distribution is predictable. SIZE ? ? Freescale Semiconductor, Inc... ? ? ? ? ? ? ? ? ? PREDICTION Lower Specification Limit Upper Specification Limit In control and capable (variation from random TIME variability reduced) TIME SIZE Figure 2. Impact of Assignable Causes on Process Predictable At Motorola, for critical parameters, the process capability is acceptable with a Cpk = 1.33. The desired process capability is a Cpk = 2 and the ideal is a Cpk = 5. Cpk, by definition, shows where the current production process fits with relationship to the specification limits. Off center distributions or excessive process variability will result in less than optimum conditions SPC IMPLEMENTATION AND USE DMTG uses many parameters that show conformance to specification. Some parameters are sensitive to process variations while others remain constant for a given product line. Often, specific parameters are influenced when changes to other parameters occur. It is both impractical and unnecessary to monitor all parameters using SPC methods. Only critical parameters that are sensitive to process variability are chosen for SPC monitoring. The process steps affecting these critical parameters must be identified also. It is equally important to find a measurement in these process steps that correlates with product performance. This is called a critical process parameter. Once the critical process parameters are selected, a sample plan must be determined. The samples used for measurement are organized into RATIONAL SUBGROUPS of approximately 2 to 5 pieces. The subgroup size should be such that variation among the samples within the subgroup remain small. All samples must come from the same source e.g., the same mold press operator, etc.. Subgroup data should be collected at appropriate time intervals to detect variations in the process. As the process begins to show 1-14 SIZE In control but not capable (variation from random variability excessive) Figure 3. Difference Between Process Control and Process Capability improved stability, the interval may be increased. The data collected must be carefully documented and maintained for later correlation. Examples of common documentation entries would include operator, machine, time, settings, product type, etc. Once the plan is established, data collection may begin. The data collected will generate X and R values that are plotted with respect to time. X refers to the mean of the values within a given subgroup, while R is the range or greatest value minus least value. When approximately 20 or more X and R values have been generated, the average of these values is computed as follows: X = ( X + X2 + X 3 + ...)/K R = (R1 + R2 + R3 + ...)/K where K = the number of subgroups measured. The values of X and R are used to create the process control chart. Control charts are the primary SPC tool used to signal a problem. Shown in Figure 4, process control charts show X and R values with respect to time and concerning reference to upper and lower control limit values. Control limits are computed as follows: + UCLR + D4 R R lower control limit + LCL + D3 R R X upper control limit + UCL + ) A2 R X X X lower control limit + LCL + * A2 R X X R upper control limit For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 Freescale Semiconductor, Inc. 154 153 UCL = 152.8 152 151 X = 150.4 150 149 148 LCL = 148.0 147 UCL = 7.3 7 6 5 Freescale Semiconductor, Inc... 4 R = 3.2 3 2 1 LCL = 0 0 Figure 4. Example of Process Control Chart Showing Oven Temperature Data Where D4, D3 and A2 are constants varying by sample size,with values for sample sizes from 2 to 10 shown in the following partial table: n 2 3 4 5 6 7 8 9 10 D4 3.27 2.57 2.28 2.11 2.00 1.92 1.86 1.82 1.78 D3 * * * * * 0.08 0.14 0.18 0.22 A2 1.88 1.02 0.73 0.58 0.48 0.42 0.37 0.34 0.31 * For sample sizes below 7, the LCLR would technically be a negative number; in those cases there is no lower control limit; this means that for a subgroup size 6, six "identical" measurements would not be unreasonable. Control charts are used to monitor the variability of critical process parameters. The R chart shows basic problems with piece to piece variability related to the process. The X chart can often identify changes in people, machines, methods, etc. The source of the variability can be difficult to find and may require experimental design techniques to identify assignable causes. Some general rules have been established to help determine when a process is OUT-OF-CONTROL. Figure 5 shows a control chart subdivided into zones A, B, and C corresponding to 3 sigma, 2 sigma, and 1 sigma limits respectively. In Figure 6 through Figure 9 four of the tests that can be used to identify excessive variability and the presence of assignable causes are shown. As familiarity with a given process increases, more subtle tests may be employed successfully. Once the variability is identified, the cause of the variability must be determined. Normally, only a few factors have a significant impact on the total variability of the process. The importance of correctly identifying these factors is stressed in the following example. Suppose a process variability depends on the variance of five factors A, B, C, D and E. Each has a variance of 5, 3, 2, 1 and 0.4 respectively. Motorola Sensor Device Data + s A2 ) s B2 ) s C2 ) s D2 ) s E2 s tot + 52 ) 32 ) 2 2 ) 12 ) (0.4) 2 + 6.3 Since: s tot + Now if only D is identified and eliminated then; s tot 52 ) 32 ) 22 ) (0.4)2 + 6.2 This results in less than 2% total variability improvement. If B, C and D were eliminated, then; s tot + 52 ) (0.4)2 + 5.02 This gives a considerably better improvement of 23%. If only A is identified and reduced from 5 to 2, then; s tot + 22 ) 32 ) 22 ) 12 ) (0.4)2 + 4.3 Identifying and improving the variability from 5 to 2 gives us a total variability improvement of nearly 40%. Most techniques may be employed to identify the primary assignable cause(s). Out-of-control conditions may be correlated to documented process changes. The product may be analyzed in detail using best versus worst part comparisons or Product Analysis Lab equipment. Multi-variance analysis can be used to determine the family of variation (positional, critical or temporal). Lastly, experiments may be run to test theoretical or factorial analysis. Whatever method is used, assignable causes must be identified and eliminated in the most expeditious manner possible. After assignable causes have been eliminated, new control limits are calculated to provide a more challenging variability criteria for the process. As yields and variability improve, it may become more difficult to detect improvements because they become much smaller. When all assignable causes have been eliminated and the points remain within control limits for 25 groups, the process is said to be in a state of control. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-15 Freescale Semiconductor, Inc. UCL UCL A ZONE A (+ 3 SIGMA) B ZONE B (+ 2 SIGMA) C ZONE C (+ 1 SIGMA) CENTERLINE ZONE C (- 1 SIGMA) C ZONE B (- 2 SIGMA) B A ZONE A (- 3 SIGMA) LCL Figure 5. Control Chart Zones Figure 6. One Point Outside Control Limit Indicating Excessive Variability Freescale Semiconductor, Inc... UCL UCL A A B B C C C C B B A LCL A LCL Figure 7. Two Out of Three Points in Zone A or Beyond Indicating Excessive Variability LCL Figure 8. Four Out of Five Points in Zone B or Beyond Indicating Excessive Variability UCL A B C C B A LCL Figure 9. Seven Out of Eight Points in Zone C or Beyond Indicating Excessive Variability SUMMARY Motorola's commitment to STATISTICAL PROCESS CONTROLS has resulted in many significant improvements to processes. Continued dedication to the SPC culture will 1-16 allow Motorola to reach beyond Six Sigma and zero defect capability goals. SPC will further enhance the commitment to TOTAL CUSTOMER SATISFACTION. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Micromachined Accelerometer Reliability Testing Results LIFE AND ENVIRONMENTAL TESTING RESULTS STRESS TEST High Temperature Bias TA = 90C, VDD = 5.0 V t = 1000 hours, 12 minutes on, 8 seconds off 0/32 High Temperature/High Humidity Bias TA = 85C, RH = 85%, VDD = 5.0 V, t = 2016 0/38 High Temperature Storage (Bake) TA = 105C, t = 1000 hours 0/35 Temperature Cycle Freescale Semiconductor, Inc... RESULTS FAILED/PASS CONDITIONS Mechanical Shock *40 to 105C, Air to Air, 15 minutes at extremes, v 5 minutes transfer, 1000 cycles 5 blows X1, X2, Y1, Y2, Z1, Z2 2.0 G's, 0.5 mS, TA = *40C, 25C, 90C 0/23 0/12 Vibration Variable Frequency with Temperature Cycle 10 - 1 Khz @ 50 G's max, 24 hours each axis, X1, X2, Y1, Y2, Z1, Z2, TA = 40 to 90C, Dwell = 1 Hour, transfer = 65 minutes 0/12 Autoclave TA = 121C, RH = 100% 15 PSIG, t = 240 hours 0/71 Drop Test 10 Drops from 1.0 meters onto concrete, any orientation 0/12 * PARAMETERS MONITORED LIMITS INITIAL PARAMETER Offset Self Test Sensitivity CONDITIONS * VDD = 5.0 V, 25, *40 & 90C VDD = 5.0 V, 25, *40 & 90C VDD = 5.0 V, 25, 40 & 90C Motorola Sensor Device Data END POINTS MIN MAX MIN MAX 2.15 V 2.95 V 2.15 V 2.95V 20G 30 G 20 G 30 G 45 mV/G 55 mV/G 45 mV/G 55 mV/G www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-17 Freescale Semiconductor, Inc. Media Compatibility Disclaimer Motorola has tested media tolerant sensor devices in selected solutions or environments and test results are based on particular conditions and procedures selected by Motorola. Customers are advised that the results may vary for actual services conditions. Customers are cautioned that they are responsible to determine the media compatibility of sensor devices in their applications and the foreseeable use and misuses of their applications. Sensor Media Compatibility: Issues and Answers T. Maudie, D. J. Monk, D. Zehrbach, and D. Stanerson Motorola Semiconductor Products Sector, Sensor Products Division 5005 E. McDowell Rd., Phoenix, AZ 85018 Freescale Semiconductor, Inc... ABSTRACT As sensors and actuators are embedded deeper into electronic systems, the issue of media compatibility as well as sensor and actuator performance and survivability becomes increasingly critical. With a large number of definitions and even more explanations of what media compatibility is, there is a ground swell of confusion not only within the industry, but among end users as well. The sensor industry must respond to create a clear definition of what media compatibility is, then strive to provide a comprehensive understanding and industry wide agreement on what is involved in assessing media tolerance and compatibility. Finally, the industry must create a standard set of engineering parameters to design, evaluate, test, and ultimately qualify sensor and actuators functioning in various media conditions. This paper defines media compatibility, identifies pertinent compatibility issues, and recommends a path to industry standardization. INTRODUCTION Microelectromechanical System (MEMS) reliability in various media is a subject that has not yet received much attention in the literature yet [1-3], but does bring up many potential issues. The effects of long term media exposure to the silicon MEMS device and material still need answers [4]. Testing can result in predictable silicon or package related failures, but due to the complexity of the mechanisms, deleterious failures can be observed. The sensor may be exposed to diverse media in markets such as automotive, industrial, and medical. This media may include polar or nonpolar organic liquids, acids, bases, or aqueous solutions. Integrated circuits (ICs) have long been exposed to temperature extremes, humid environments, and mechanical tests to demonstrate or predict the reliability of the device for the application. Unlike a typical IC, a sensor often must exist in direct contact with a harsh environment. The lack of harsh media simulation test standardization for these direct contact situations necessitates development of methods and hardware to perform reliability tests. The applicability of media compatibility affects all sensors to some degree, but perhaps none more dramatically than a piezoresistive pressure sensor. In order to provide an accurate, linear output with applied pressure, the media should come in direct contact with the silicon die. Any barrier provided between the die and the media, limits the device performance. A typical piezoresistive diaphragm pressure sensor manufactured using bulk micromachining techniques is shown in Figure 1. A definition for a media compatible pressure sensor will be proposed. To ensure accurate media testing, the requirements and methods need to be understood, as well as what constitutes a failure. An understanding of the physics of failure can significantly reduce the development cycle time and produce a higher quality product [5,6]. The focus of the physics-of-failure approach includes the failure mechanism, accelerating environment, and failure mode. The requirement for a typical pressure sensor application involves long term exposure to a variety of media at an elevated temperature and may include additional acceleration components such as static or cyclic temperature and pressure. DIAPHRAGM DIFFUSED STRAIN GAUGE METALLIZATION EEE SILICON WAFER ETCHED CAVITY DIE RTV DIE BOND WIRE INTERCONNECT LEAD FRAME EPOXY CASE This paper was presented at Sensors Expo, Anaheim, CA, and is reprinted with permission, Sensors Magazine (174 Concord St., Peterborough, NH 03458) and Expocon Management Associates, Inc. (P.O. Box 915, Fairfield, CT 06430). 1-18 Figure 1. Typical bulk micromachined silicon piezoresistive pressure sensor device and package configuration. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. The failure mechanisms that may affect a sensor or actuator will be discussed along with the contributors and acceleration means. Failure mechanisms of interest during media testing of semiconductor MEMS devices are shown in Table 1. MEMS applications may involve disposable applications such as a blood pressure monitor whose lifetime is several days. General attributes to consider during testing include: lifetime expectations, cost target, quality level, size, form, and functionality. Table 1. Typical Failure Mechanisms for Sensors and Actuators [6-10] Failure Mechanism Uniform Corrosion environment and permeability of the environment. The environment may consist of media or moisture with ionics, organics, and/or aqueous solutions, extreme temperatures, voltage, and stress. Permeability is the product of diffusivity and solubility. Contributors to permeability include materials (e.g. polymeric structures), geometry, processing, and whether or not the penetration is in the bulk or at an interface. The environment can also accelerate permeation if a concentration gradient, elevated temperature and/or pressure exist. An example of material dependence of permeation is shown in Figure 2. Organic materials such as silicone can permeate 50% of the relative moisture from the exterior within minutes where inorganic materials such as glass takes years for the same process to occur. Localized Corrosion PERMEABILITY (g/cm-s-torr) -1 10-6 10-8 10-10 10-12 10-14 10-16 Silicon Etching Polymer Swelling or Dissolution -2 Interfacial Permeability LOG THICKNESS (m) Freescale Semiconductor, Inc... Galvanic Corrosion Adhesive Strength Fatigue Crack Initiation Fatigue Crack Propagation Environment Assisted Cracking EPOXIES FLUORO-CARBONS -3 GLASSES -4 -5 Creep METALS Methods for performing media compatibility testing to determine the potential for the various failure mechanisms will be presented. Attributes of the testing need to be well understood so that proper assessment of failure and lifetime approximation can be made. The lifetime modeling is key for determination of the ability of a sensor device to perform its intended function. Reliability modeling and determination of activation energies for the models will provide the customer with an understanding of the device performance. The definition of an electrical failure can range from catastrophic, to exceeding a predetermined limit, to just a small shift. The traditional pre to post electrical characterization (before and after the test interval) can be enhanced by in situ monitoring. In situ monitoring may expose a problem with a MEMS device during testing that might have gone undetected once the media or another environmental factor is removed. This is a common occurrence for a failure mechanism, such as swelling, that may result in a shift in the output voltage of the sensor. Response variables during environmental testing can include: electrical, visual, analytical, or physical characteristics such as swelling or weight change. DEFINITIONS & UNDERLYING CAUSES The definition of a media compatible pressure sensor is as follows: The ability of a pressure sensor to perform its specified electromechanical function over an intended lifetime in the chemical, electrical, mechanical, and thermal environments encountered in a customer's application. The key elements of the definition are perform, function, lifetime, environment, and application. All of these elements are critical to meet the media compatibility needs. The underlying causes of poor media compatibility is the hostile Motorola Sensor Device Data SILICONES -6 MIN HR DAY MO YR 10 YR 100 YR TIME FOR PACKAGE INTERIOR TO REACH 50% OF EXTERIOR HUMIDITY * Figure 2. Permeation relationship for various materials. * Richard K. Traeger, "Nonhermiticity of Polymeric Lid Sealants, IEEE Transactions on Parts, Hybrids, and Packaging, Vol. PHP-13, No. 2, June 1977. Gasoline and aqueous alkaline solutions represent two relatively diverse applications that are intended for use with a micromachined pressure sensor. The typical automotive temperature range is from -40 to 150C. This not only makes material selection more difficult but also complicates the associated hardware to perform the media related testing [11]. A typical aqueous alkaline solution application would be found in the appliance industry. This industry typically has a narrower temperature extreme then the automotive market, but the solutions and the level of ions provide a particular challenge to MEMS device reliability. Gasoline contains additives such as: antiknock, anti-preignition agents, dyes, antioxidants, metal deactivators, corrosion inhibitors, anti-icers, injector or carburetor detergents, and intake valve deposit control additives [12]. To develop a common test scheme for the liquid, a mixture table was developed for material testing in gasoline/methanol mixtures. The gasoline/methanol mixtures developed were intended for accelerated material testing with a gasoline surrogate of ASTM Fuel Reference "C" (50% toluene and 50% iso-octane) [13]. Material testing is performed with samples either immersed in the liquid or exposed to the vapor over the liquid. The highly aromatic Fuel www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-19 Freescale Semiconductor, Inc. "C" is intended to swell polymeric materials. Contaminants in actual gasoline can result in corrosion or material degradation, so chloride ions or formic acid with distilled water are added to create an aggressive fuel media. Gasoline can decompose by a process called auto-oxidation that will form aggressive substances that can dissolve polymers or corrode metal. Copper is added as a trace metal to accelerate the formation of free radicals from the hydroperoxides. Table 2 details the various gasoline/methanol mixtures with additives recommended by the task force from Chrysler, Ford, and General Motors. Table 2. Fuel Testing Methods Elastomer Alcohol/Fuel Blends Metal CMO CMO CM15 CM15 CM30 CM30 CM50 CM50 CM85 CM85 CM85 Chloride ion Distilled water Formic Acid Chloride ion Sodium Chloride Formic Acid t-Butyl Hydroperoxide t-Butyl Hydroperoxide Aggressive Fuel, Add Freescale Semiconductor, Inc... Polymer Auto Oxidized Fuels, Add CM15 Cu+ Recommended gasoline/methanol mixtures for material testing. The recommended testing for metals should include immersion in the liquid as well as exposure to the vapor. The coding for the alcohol/fuel blends, CMxx is: C for Fuel C; M for methanol; and xx indicating the percentage of methanol in the mixture. The general question for the appliance industry compatibility issues is not whether the media will contain ions (as it most assuredly will) but at what concentration. Tap water with no alkali additives contains ions capable of contributing to a corrosive reaction [14]. A typical application of a pressure sensor in the appliance industry is sensing the water level in a washing machine. The primary ingredients of detergent used in a washing machine are: surfactants, builders, whitening agents and enzymes [15]. The surfactants dissolve dirt and emulsify oil, grease and dirt. They can be anionic or cationic. Cationic surfactants are present in detergent-softener combinations. Builders or alkaline water conditioning agents are added to the detergent to soften the water, thus increasing the efficiency of the surfactant. These builders maintain alkalinity that results in improved cleaning. Alkaline solutions at temperatures indicated by the appliance industry range can etch bare silicon similar to the bulk micromachining process. Thus bare silicon could be adversely affected by exposure to these liquids [16]. FAILURE MECHANISMS The failure mechanisms that can affect sensors and actuators are similar to that for electronic devices. These failure mechanisms provide a means of categorizing the varIous effects caused by chemical, mechanical, electrical, and thermal environments encountered. An understanding of the potential failure mechanisms should be determined before media testing begins. The typical industry scenario has been to follow a set boiler plate of tests and then determine reliability. This may have been acceptable for typical electronic devices, but the applications for sensors are more demanding of a thorough understanding before testing begins. The sensitivity of the device to its physical environment is heightened for a pressure sensor. Any change in the 1-20 material properties results in a change of the sensor performance. Failure mechanisms for pressure sensors in harsh media application are listed below. The pressure sensor allows a format for discussion, though the mechanisms discussed are applicable in some degree to all sensor and actuator devices. Corrosion Corrosion has been defined as any destructive result of a chemical reaction between a metal or metal alloy and its environment [17]. Several metal surfaces exist within a pressure sensor package: metallic lines on the die, trimmable resistors, bonding pads, wires, leadframes, etc. Much of the die-level metal is protected by an overlying inorganic passivation material (e.g., PECVD silicon nitride); however, unless some package-level encapsulant is used, bondpads, wires, and leadframes are exposed to the harsh media and are potential corrosion sites. Furthermore, an energized pressure sensor has a voltage difference between these exposed metallic surfaces, which compounds the corrosion problem. Generally, corrosion problems are organized into the following categories: uniform corrosion; galvanic corrosion, and localized corrosion (including, crevice corrosion, pitting corrosion, etc.) [17]. The factors that contribute to corrosion are: the substrate (metallic) material and its surface structure and composition; the influence of a barrier coating, its processing conditions and/or adhesion promotion; the cleanliness of the surface, adhesion between a coating and the surface, solution concentration, solution components (especially impurities and/or oxidizers); localized geometry and applied potential. In addition, galvanic corrosion is influenced by specific metal-to-metal connections. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PIEZORESISTIVE TRANSDUCER DIAPHRAGM SILICON DIE UNIBODY PACKAGE LEAD FRAME DIE ATTACH WIREBOND Freescale Semiconductor, Inc... NITRIC Figure 3. Examples of uniform corrosion of a gold leadframe in nitric acid at 5 Vdc and galvanic corrosion on an unbiased device at the gold wire/aluminum bondpad interface in commercial detergent. Part of figure 3 shows an example of what we have described as electrolytic corrosion (i.e., corrosion of similar metallic surfaces in an electrolytic solution caused by a sufficient difference in potential between the two surfaces). This appears to be uniform corrosion of the gold leadframe surface. It should be noted that this type of failure is observed even on `noble' metals like gold. Applied potential is the driving force for the reaction. All metals can corrode in this fashion depending on the solution concentration (pH) and the applied potential. Pourbaix diagrams describe these thermodynamic relationships [18]. Figure 3 shows an example of galvanic corrosion. The figure illustrates that corrosion can also occur because of dissimilar metals that are connected electrically and are immersed in an electrolytic solutions. A difference in the corrosion potential between the two metals is the driving force for the reaction. Localized corrosion examples are prevalent as well. Often they may be the precursor to what appears on a macro scale to be uniform or galvanic corrosion. In situ monitoring of devices in electrolytic media will allow better diagnosis of this failure mechanism. Typical ex situ or interval reliability testing may not allow diagnosis of the root cause to the failure, thus limiting the predictive power of any resulting reliability models. Silicon Etching Figure 4 shows the result of an accelerated test of a pressure sensor die to a high temperature detergent solution. The detergent used was a major consumer brand and resulted in dramatic etching of the silicon. Alkaline solutions that undergo a hydrolysis reaction may result in etching of the silicon similar to a bulk micromaching operation. This failure mechanism can cause a permanent change in the sensitivity of the device because the sensitivity is proportional to the Motorola Sensor Device Data inverse square of the silicon thickness. Moreover, it can lead to loss in bond integrity between wafers (Fig. 4). Silicon etching [19-20], like corrosion reactions, is a chemical reaction, so the contributing factors include the silicon material, its crystal orientation and its doping level, the solution type, concentration and pH, and the applied potential. Temperature, concentration (i.e., pH), and voltage all act to accelerate this process. Figure 5 shows an example of modeling results that illustrates two of these variables. Figure 4. Photograph of silicon etching after exposure to an aqueous detergent solution at elevated temperature for an extended time. A frit layer, horizontally in the middle, adheres to silicon on either side. The amount of etching is evident by referencing the glass frit edge on the far left. These two silicon edges were aligned to the frit edge when the die was sawn. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-21 Freescale Semiconductor, Inc. Solvents Contour Plot of Detergent Concentraion and Temperature vs Etch Rate ( m m/hr) ISOOCTANE Polymers PTFE 7.5 POLYSULFONE POLYURETHANE PMMA PET TOLUENE 10 ETHANOL 12.5 NYLON 120 110 METHANOL 15 POLY (ACRYLONITRILE) TEMP (C) 100 17.5 90 20 80 Freescale Semiconductor, Inc... 22.5 WATER 70 = [cal/cm3]1/2 60 0 10 20 30 40 50 Figure 6. Typical values of solubility parameter ( [cal/cm3]1/2) for solvents and polymers. ULTRA TIDE CONC (g/l) Etch Rate Prediction from Model <= 0.10 <= 0.40 <= 0.20 > 0.40 <= 0.30 Figure 5. Experimental results for the etching of (100) silicon with approximately 5x10-5 cm-3 boron doping density in a commercially available detergent as a function of temperature and detergent concentration (which is proportional to pH). Polymer Swelling or Dissolution Swelling or dissolution affects those polymers typically employed to package the micromachined structure and depending on the nature of the media, may have a degrading effect on device performance. These two related phenomena are caused by solvent diffusing into the material and occupying free volume within the polymer. The solubility parameter gives a quantitative measure of the potential for swelling [21]: i.e., it provides a quantitative measure of "like dissolves like" (Fig. 6). Both the polymer and the solution contribute to this failure mechanism, while the media (specifically, the solubility parameter), the temperature, and the pressure can be used as acceleration factors. Figure 7 shows a photograph of a device after exposure to a harsh fuel containing corrosive water solution. This corrosion and evidence of swelling of the gel demonstrates the vital importance the package has on the reliability of the pressure sensor device. Also, it has been observed that corrosion occurs more readily following swelling of a polymeric encapsulant. INITIAL EDGE OF GEL GEL EDGE AFTER EXPOSURE TO GASOLINE WITH ETHANOL Figure 7. Photograph of a pressure sensor device after extended exposure to harsh fuel containing corrosive water, followed by exposure to a strong acid. Evidence of the gel swelling during the test, and corresponding shrinkage after removal from the test media can be seen by the gel retracting away from the sidewall of the package. 1-22 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Interfacial Permeability Lead leakage is a specific example of interfacial permeability. It is pressure leakage through the polymer housing material/metallic leadframe material interface from the inside of the pressure sensor package to the outside of the pressure sensor package or vice versa [22]. In addition, other material interfaces can result in leakage. We describe another specific example of this in the next section. Lead leakage is like polymer swelling in that it may allow another failure mechanism, like corrosion, to occur more readily. It also causes a systematic pressure measurement error. Figure 8 shows the result of lead leakage measurements as a function of temperature cycling. The polymer housing material (and its CTE as a function of temperature), the leadframe material (and its CTE), surface preparation and contamination, the polymer matrix composition, and polymer processing all contribute to this effect. It is accelerated by media, temperature cycling, and applied pressure. 2.0 EPOXY PPS GRADE 1 1.5 LEAD LEAKAGE (cc/min) Freescale Semiconductor, Inc... PPS GRADE 2 PBT LCP 1.0 0.5 0.0 0 200 400 600 800 1000 TEMPERATURE CYCLES Figure 8. Pressure leakage measurements through the metallic leadframe/polymeric housing material interface on a pressure sensor as a function of temperature cycles between -40 and 125C. Adhesive Strength Packaging of the sensor relies on adhesive material to maintain a seal but not impart stress on the piezoresistive element. Polymeric materials are the primary adhesive materials which can range from low modulus material such as silicone to epoxy with a high modulus. An example of a typical joint is shown in Figure 9. The joint has three possible failure locations with the preferred break being cohesive. Contributors to a break include whether the joint is in tension or compression, residual stresses, the adhesive material, surface preparation, and contamination. An adhesive failure is accelerated by media contact, cyclic or static temperature, and cyclic or static stress (e.g. pressure). Strength Components DIE TO MAT'L ADHESIVE STRENGTH COHESIVE STRENGTH DIE TO EPOXY ADHESIVE STRENGTH Figure 9. Failure locations for an adhesive bond of dissimilar materials. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-23 Freescale Semiconductor, Inc. Mechanical Failures The occurrence of mechanical failures include components of fatigue, environment assisted cracking, and creep. Packaging materials, process, and residual stresses are all contributors to mechanical failure. A summary of acceleration stresses is shown in Table 3. Contact with harsh media is an accelerating stress for all of the mechanical failure mechanisms. PRESSURE SENSOR SOLUTIONS The range of solutions for pressure sensors to media compatibility is very diverse. Mechanical pressure sensors still occupy a number of applications due to this media compatibility concern. These devices typically operate on a variable inductance method and are typically not as linear as a piezoresistive element. Figure 10 shows a comparison between a mechanical pressure sensor and a piezoresistive element for a washing machine level sensing application. The graph shows a nonlinear response for the mechanical sensor and a corresponding straight line for the piezoresistive element. A common method of obtaining media compatibility is to place a barrier coating over the die and wire interconnection. This organic encapsulant provides a physical barrier between the harsh environment and the circuitry. The barrier coating can range from silicone to parylene or other dense films that are typically applied as a very thin layer. This technique offers limited protection to some environments due to swelling and/or dissolution of the encapsulant material when in contact with media with a similar solubility. When a polymeric material has a solubility parameter of the same value as the corresponding media, swelling or dissolution will occur. Stainless steel diaphragms backfilled with silicone oil provide a rugged barrier to most media environments, but generally are very costly and limit the sensitivity of the device. The silicone oil is used to transmit the stress from the diaphragm to the piezoresistive element. If a polymeric material is used as the die attach, the silicone oil will permeate out of the package. This concern requires a die attach that is typically of higher modulus than a silicone and may not adequately isolate the package stress from the die. Table 3. Mechanical Failure Mechanisms Acceleration Stresses Fatigue crack initiation Mechanical stress/strain range Cyclic temperature range Frequency Media Fatigue crack propagation Mechanical stress range Cyclic temperature range Frequency Media Environment assisted cracking Mechanical stress Temperature Media Creep Mechanical stress Temperature Media 175 1.8 1.6 165 1.4 1.2 160 1 155 0.8 150 0.6 0.4 145 0.2 PIEZORESISTIVE PRESSURE SENSOR OUTPUT (VOLTS) 2 170 MECHANICAL SENSOR OUTPUT (HERTZ) Freescale Semiconductor, Inc... Failure Mechanism 0 140 0 1 2 3 4 5 6 TIME (MINUTES) WASHING MACHINE SENSOR PIEZORESISTIVE PRESSURE SENSOR Figure 10. Graphical comparison of the output from a mechanical pressure sensor compared to a piezoresistive sensor during a washing machine fill cycle. 1-24 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MEDIA TEST METHODS Figures 11 and 12 show a test apparatus specifically intended for use with solvents and Figure 13 an apparatus for aqueous solutions. This test system has resulted in a realistic test environment that provides electrical bias, in situ measurements, FLUORINATED HYDROCARBON LIQUID WITH EXTERNAL HEATER consistent stoichiometry, and temperature control all within a safe environment. The safety aspects of the testing were obtained by creating an environment free of oxygen to eliminate the possibility of a fire. Results from the testing have included swelling of silicone materials, corrosion, and adhesive failures. TO AUTOMATIC TEST SYSTEM WITH VOLTAGE AND CURRENT LINKING PROTECTION THERMOCOUPLES POROUS NITROGEN PURGE LINES ELECTRICAL CONNECTIONS CONDENSER COILS LID MODULAR TEST PLATE WITH O-RING SEAL Freescale Semiconductor, Inc... SENSORS L I Q U I D V A P O R TANK 1 FROM PUMP LOADING CHAMBER TANK 2 TO PUMP TO DRAIN Figure 11. Graphical depiction of the sensor media tester used for liquid or vapor exposure of the device to the harsh media to accelerate the failure mechanisms or demonstrate compatibility. Figure 12. Photograph of the load chamber area of the Media Test System allowing for fuel or solvent testing at temperature with in situ monitoring of the devices under test (DUT's) output. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-25 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. Figure 13. Photograph of the aqueous alkaline solution test system and the data acquisition system for in situ monitoring of the MEMS devices. LIFETIME MODELING Reliability techniques provide a means to analyze media test results and equate the performance to a lifetime [23-24]. The primary reliability techniques involve an understanding of the failure rate, life distributions, and acceleration modeling. The failure rate for a product's lifetime follows the bathtub curve. This curve, as shown in Figure 14, has an early life period with a decreasing failure rate. Manufacturing defects would be an example of failures during this portion of the curve. The second portion of the curve, often described as the useful life region has a constant failure rate. The last section has an increasing failure rate and is referred to as the wearout region. This wearout region would include failure mechanisms such as corrosion or fatigue. Product Failure Rate END OF LIFE OR WEAR OUT FAILURE RATE INFANT MORTALITY OR EARLY LIFE FAILURE RATE STEADY STATE FAILURE RATE Time Figure 14. Bathtub curve showing various failure rate regions. Lifetime distributions provide a theoretical model to describe device lifetimes. Common lifetime distributions include the exponential, Weibull, lognormal, and extreme value. The exponential distribution models a lifetime with a 1-26 constant failure rate An example of the exponential distribution is a glass which has an equal probability of failing the moment after it is manufactured, or when its ten years old. The Weibull and lognormal distribution are all right, or www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. positively skewed distributions. A right skewed distribution will be a good model for data in a histogram with an extended right tail. The Weibull distribution is sometimes referred to as a distribution of minima. An example of a Weibull distribution is the strength to break a chain where the weakest link describes the strength of the chain. The extreme value distribution is a distribution of maxima. It is the least utilized of the four life distributions. For means of example, the Weibull distribution will be used. The Weibull lifetime distribution has the form: +1*e b (1) . The two parameters for the Weibull distribution are q and b. Theta is the scale parameter, or characteristic life. It represents the 63.2 percentile of the life distribution. Beta is the shape parameter. In order to determine the parameters for the Weibull distribution, testing must be performed produce failure on the devices. The failure data can be used to calculate the maximum likelihood estimates or determined graphically. It has not always been customary to perform reliability demonstration testing until failures occur. In regards to media testing, this seems to be the only method to derive lifetime estimates that reflect a true understanding of the device capability. AF + e Ea k 1 T low *T 1 high * RH high RH low n (2) , 100% 90% PROBABILITY OF FAILURE, F (t) Freescale Semiconductor, Inc... F(t, , ) * qt A media test typically needs to take results received in weeks or months to predict lifetime in years. Acceleration models are used to determine the relationship between the accelerated test and the normal lifetime. Literature has reported numerous models to equate testing to lifetime including the Peck model for temperature and humidity [25]. The acceleration equation based on Peck's model is where Ea is 0.9eV and n is -3.0. The value K is Boltzmann's constant which is equal to 8.6171x10-5 eV/K. The relative humidity is entered as a whole number, i.e. 85 for 85%. Using this sample model, test results from humidity testing can be related to the lifetime. The methods to equate test time to lifetime first involves fitting the failure data to a lifetime distribution. For an example, humidity data at 60C, 90% relative humidity and bias was tested to failure. The failure data fit a Weibull distribution with a characteristic life of 40,000 hours. By applying the acceleration factor equation shown above, quantification of the lifetime in the use conditions can be calculated. Figure 15 shows the cumulative failure distribution for the test and use conditions for a 15 year lifetime. This technique is key for media testing since the range of use conditions is very broad. The consumer can determine the attributes for the sensor to use for the application. The attributes might include cost, performance, and possibility for replacement. 80% Test Condition (60 _C, 90% RH) 70% 60% 50% 40% 30% 20% (30 _C, 85% RH) 10% (25 _C, 60% RH) 0% 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 TIME (YEARS) Figure 15. Probability of failure versus time for humidity testing with bias on an integrated sensor device. The failure distribution example shown typically represents one failure mechanism. The failure mechanism that typifies humidity testing is mobile ions. An elevated test temperature, humidity and bias contributes to the mobility of the ions and the ability to create a surface charge. By lowering the temperature, humidity or switching the bias, an improvement in the lifetime can be obtained. If a device manufacturer would test to failure and report the lifetimes, the customer could select the appropriate product for their application. Following a template of reliability tests that have not been verified and Motorola Sensor Device Data do not coincide with the applicable failure mechanism may put the application at risk for surviving. Humidity testing was used as an example above, but a similar case could be made of other attributes involved with media testing. Other attributes of the media test may include the bias level and duty cycle, the pH or conductivity of the solution, and any stress such as a pressure differential. By modeling these attributes against the various solutions, models for media compatibility can be developed. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-27 Freescale Semiconductor, Inc. INDUSTRY STANDARDIZATION Why an industry standard? The increasing use of electronic sensors in everyday life has designers wrestling with the complexity of defining the compatibility of a sensor with the media they are measuring. A designer may decide to solve the question of media compatibility by choosing to isolate the sensor from the media via a stainless steel diaphragm. While this solution provides very good media isolation, it is not without some drawbacks such as cost, size of packaging, decreased sensitivity and long term drift. Without a recognized standard for defining media compatibility, the designer is left to a series of ad hoc test methods and conflicting specifications. An industry media compatibility standard will provide the designer with a method of evaluating sensor performance. The designer could match an application's requirements, for media compatibility, with the available sensor products thus taking price and performance into account. This will enable the designer to minimize the total cost of an application. A standard will also enable suppliers to provide products warranted to defined criteria. Once a standard is adopted, the suppliers may rationalize their test efforts and pass the savings on to their customers. A standard should provide a designer with a simple, coherent, complete definition of a media's effects on a sensor. The standard should included an accepted test methodology, test equipment guidelines, life time model, acceleration factors model, and a definition of failures. A proposed list of criteria to include in a model are shown in table 4. Freescale Semiconductor, Inc... Table 4. Suggested Criteria for Media Compatibility Media Contact -- Front or Back Supply Voltage Solubility Parameter Pressure Range Supply Voltage Duty Cycle Conductivity of Media Temperature Range Voltage Potential within Media pH Recipe of Media and Contaminants Frequency Output is Measured Lifetime Expectancy Sensor to Media Interconnection Relative Motion of Media (e.g., Flow) These criteria must be included not only for the media, but also for the contaminants in the media. An example is a washing machine level sensor which must be compatible with water vapor (the media) and detergent and chlorine (the contaminant). To create a standard, a series of tests which benchmark the criteria must be designed and performed. The results would form the basis of the life time and acceleration factor models. There are several ways to create a standard, each of which have their own associated pros and cons. Three possible ways to create a standard are: an industry association committee, a panel of industry representatives, or a de facto standard set by one or more industry suppliers. To define a standard for media compatibility may require more than one of these methods. An industry leader may define a standard form to which they deliver product. This may stimulate the formation of a committee which defines a broader standard for the industry. As this standard becomes more accepted by the industry, the committee may work with an industry association to "legitimize" the de facto standard. No matter how the standard is formulated, receiving broad industry acceptance will require meeting the customers' needs. 1-28 CONCLUSION Investigation of media compatibility for pressure sensors has been presented from a physics-of-failure approach. We have developed a set of internal standard test and reliability lifetime analysis procedures to simulate our customers' requirements. These activities have incorporated information from several fields beyond sensors and/or electronics, including: electrochemistry and corrosion, polymers, safety and environmental, automotive and appliance industry standards, and reliability. The next critical step to elevating the awareness of this problem, in our opinion, is to develop an industry-wide set of standards, driven by customer applications, that include media testing experimental procedures, reliability lifetime analysis, and media compatibility reporting to allow easier customer interpretation of results. ACKNOWLEDGMENTS Many individuals have contributed to the media compatibility initiative and are deserving of an acknowledgment. The individuals include Debi Beall, Gordon Bitko, Jerry Cripe, Bob Gailey, Jim Kasarskis, John Keller, Betty Leung, Jeanene Matkin, Mike Menchio, Adan Ramirez, Chuck Reed, Laura Rivers, Scott Savage, Mahesh Shah, Mario Velez, John Wertz, MEMS1, MKL, Reliability Lab, Characterization Lab, and the Prototype Lab. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. REFERENCE Freescale Semiconductor, Inc... (1) Theresa Maudie, Testing Requirements and Reliability Issues Encountered with Micromachined Structures, Proceedings of the Second International Symposium on Microstructures and Microfabricated Systems, Eds. D. Denton, P.J. Hesketh and H. Hughes, ECS, vol. 95-27 (1995) pp. 223-230. (2) Arne Nakladal et al., Influences of Humidity and Moisture on the Long-Term Stability of Piezoresistive Pressure Sensors, Measurement, vol. 16 (1995) pp. 21-29. (3) Marin Nese and Anders Hanneborg, Anodic Bonding of Silicon to Silicon Wafers Coated with Aluminum, Silicon Oxide, Polysilicon or Silicon Nitride, Sensors and Actuators A, vol. 37-38 (1993) pp. 61-67. (4) Janusz Bryzek, Micromachines on the March, IEEE Spectrum, May 1994. (5) J. M. Hu, Physics-of-Failure-Based Reliability Qualification of Automotive Electronics, Communications in RMS, vol. 1, no. 2 (1994) pp. 21-33. (6) Michael Pecht et.al., Quality Conformance and Qualification of Microelectronics Packages and Interconnects, John Wiley & Sons, Inc., 1994. (7) William M. Alvino, Plastics for Electronics, McGraw- Hill, 1995 (8) Eugene R. Hnatek, Integrated Circuit Quality and Reliability, Marcel Dekker, Inc., 1987. (9) Charles A. Harper, Handbook of Plastics, Elastomers, and Composites, McGraw-Hill, 1992. (10) Richard W. Hertzberg, Deformation and Fracture Mechanics of Engineering Materials, John Wiley & Sons, Inc., 1983. (11) Joseph M. Giachino, Automotive Sensors: Driving Toward Optimized Vehicle Performance, 7th Int'l Conference on Solid State Sensor and Actuators, June 1993. (12) Perry Poiss, What Additives do for Gasoline, Hydrocarbon Processing, Feb. 1973. Motorola Sensor Device Data (13) Gasoline/Methanol Mixtures for Material Testing, SAE Cooperative Research Report CRP-001, Sep. 1990. (14) Private communication to Andrew McNeil from City of Phoenix, Water and Wastewater Department, Water Quality Division, Jan. 1994. (15) Laundry Detergents, Consumer Reports, Feb. 1991, pp. 100-106. (16) Silicon as a Mechanical Material, Kurt E. Petersen, Proc. IEEE, vol. 70, no. 5, pp. 420-457, May 1982. (17) Principles and Prevention of Corrosion, Denny A. Jones, (Prentice Hall: Englewood Cliffs, NJ, 1992). (18) Atlas of Electrochemical Equilibria in Aqueous Solutions, M. Pourbaix, (Pergamon Press: Oxford, England, 1966) (19) Anisotropic Etching of Crystalline Silicon in Alkaline Solutions, Part I. Orientation Dependence and Behavior of Passivation Layers, H. Seidel et al., J. Electrochem. Soc., vol. 137, no. 11 (1990) pp. 3612-3625. (20) Anisotropic Etching of Crystalline Silicon in Alkaline Solutions, Part II. Influence of Dopants, H. Seidel et al., J. Electrochem. Soc., vol. 137, no. 11 (1990) pp. 3612-3625. (21) Principles of Polymer Systems, 2nd ed., F. Rodriguez, (Hemisphere Publishing Corporation: Washington, D.C., 1982. (22) D. J. Monk, Pressure Leakage through Material Interfaces in Pressure Sensor Packages, Sensors in Electronic Packaging, Eds. Charles Ume and Chao Pin-Yeh, MED-Vol. 3/EEP-Vol.14 (1995) pp. 87-93. (23) Paul A. Tobias and David C. Trindade, Applied Reliability, Van Nostrand Reinhold, 1995. (24) Wayne Nelson, Accelerated Testing, John Wiley & Sons, Inc., 1990. (25) O. Hallberg and D. S. Peck, "Recent Humidity Accelerations, A Base for Testing Standards," Quality and Reliability Engr. International, Vol. 7, pp 169-180, 1991. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1-29 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 1-30 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Section Two Acceleration Sensor Products Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 Accelerometer Overview: Motorola's series of acceleration sensors incorporate a surface micromachined structure. The force of acceleration moves the seismic mass, thereby changing the g-cell's capacitance. Coupled with the g-cell is a control chip to provide the accelerometer with signal amplification, signal conditioning, low pass filter and temperature compensation. With Zero-g offset, sensitivity and filter roll-off that is factory set, the device requires only a few external passives. In fact, this acceleration sensor device offers a calibrated self-test feature that mechanically displaces the seismic mass with the application of a digital self-test signal. The g-cell is hermetically sealed at the die level, creating a particle-free environment with features such as built in damping and over-range stops to protect it from mechanical shock. These acceleration sensors are rugged, highly accurate and feature X, XY, and Z axis of sensitivity. Motorola's acceleration sensors are economical, accurate and highly reproducible for the ideal sensing solution in automotive, industrial, commercial and consumer applications. Device Numbering System . . . . . . . . . . . . . . . . . . 2-2 Sensor Applications . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 Acceleration Sensor FAQ's . . . . . . . . . . . . . . . . . . 2-4 Data Sheets MMA1200D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 5 MMA1201P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12 MMA1220D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 18 MMA1250D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-24 MMA1260D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-30 MMA1270D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-36 MMA2201D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 42 MMA2202D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 48 MMA3201D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 55 Application Notes AN1559 AN1611 AN1612 AN1632 AN1635 AN1640 AN1925 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-65 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-77 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 84 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 89 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 104 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-107 Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . 2-109 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-1 Freescale Semiconductor, Inc. Mini Selector Guide Accelerometer Sensor Acceleration Range (g) Sensing Axis AC Sensitivity (mV/g) VDD Supply Voltage (Typ) (V) Zero g Output (Typ) (V) MMA1200D 250g Z axis 8.0 5.0 2.5 MMA1201P 38g Z axis 50 5.0 2.5 MMA1220D 8g Z axis 250 5.0 2.5 MMA1250D 5g Z axis 400 5.0 2.5 MMA1260D 1.5g Z axis 1200 5.0 2.5 MMA1270D 2.5g Z axis 750 5.0 2.5 MMA2200W 38g X axis 50 5.0 2.5 MMA2201D 38g X axis 50 5.0 2.5 MMA2202D 50g X axis 40 5.0 2.5 MMA3201D 38g X-Y axis 50 5.0 2.5 Freescale Semiconductor, Inc... Device Device Numbering System for Accelerometers P M M A XXXX D PROTOTYPE PACKAGE D SOIC (Surface Mount) P 16 Pin Dip W Wingback MOTOROLA MICROMACHINED ACCELEROMETER AXIS OF SENSITIVITY 1000 SERIES -- Z AXIS 2000 SERIES -- X AXIS 3000 SERIES -- X-Y AXIS 2-2 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Sensor Applications AUTOMOTIVE APPLICATIONS * * * * * * * * Airbags Rollover detection Fuel shut-off valve Crash detection Suspension control Vehicle dynamic control Braking systems Occupant safety Freescale Semiconductor, Inc... HEALTHCARE / FITNESS APPLICATIONS * * * * * * * Physical therapy Rehabilitation equipment Range of body motion measurement Pedometers Ergonomics tools Sports medicine equipment Sports diagnostic systems Motorola Sensor Device Data INDUSTRIAL / CONSUMER APPLICATIONS * * * * * * * * * * * * * * * Game pads Vibration monitoring Computer hard drive protection Appliance balance and vibration controls Seismic detection Seismic switches Security systems Security enhancement equipment Mouse control for Handheld devices Cell phone menu selection scrolling Virtual reality input devices Dead reckoning in navigation systems Bearing wear monitoring Inclinometers Robotics www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-3 Freescale Semiconductor, Inc. Acceleration Sensor FAQ's We have discovered that many of our customers have similar questions about certain aspects of our accelerometer's technology and operation. Here are the most frequently asked questions and answers that have been explained in relatively non-technical terms. Q. What is the g-cell? A. The g-cell is the acceleration transducer within the accelerometer device. It is hermetically sealed at the wafer level to ensure a contaminant free environment, resulting in superior reliability performance. Freescale Semiconductor, Inc... Q. What does the output typically interface with? A. The accelerometer device is designed to interface with an analog to digital converter available on most microcontrollers. The output has a 2.5 V DC offset, therefore positive and negative acceleration is measurable. For unique customer applications, the output voltage can be scaled and shifted to meet requirements using external circuitry. Q. What is the resonant frequency of the g-cell? A. The resonant frequency of the g-cell is much higher than the cut-off frequency of the internal filter. Therefore, the resonant frequency of the g-cell does not play a role in the accelerometer response. 2-4 Q. What is ratiometricity? A. Ratiometricity simply means that the output offset voltage and sensitivity scales linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter. Ratiometricity allows for system level cancellation of supply induced errors in the analog to digital conversion process. Refer to the Special Features section under the Principle of Operation for more information. Q. Is the accelerometer device sensitive to electro static discharge (ESD)? A. Yes. The accelerometer should be handled like other CMOS technology devices. Q. Can the g-cell part "latch''? A. No, overrange stops have been designed into the g-cell to prevent latching. (Latching is when the middle plate of the g-cell sticks to the top or bottom plate.) For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Surface Mount Micromachined Accelerometer MMA1200D The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. MMA1200D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 250g Features * Integral Signal Conditioning * Linear Output Freescale Semiconductor, Inc... * Ratiometric Performance * 4th Order Bessel Filter Preserves Pulse Shape Integrity * Calibrated Self-test 16 * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 9 * Robust Design, High Shocks Survivability 1 8 Typical Applications * Vibration Monitoring and Recording 16 LEAD SOIC CASE 475 * Impact Monitoring Pin Assignment N/C N/C N/C ST VOUT STATUS VSS VDD 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-5 Freescale Semiconductor, Inc. MMA1200D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating Gpd 500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over 2-6 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1200D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 3.0 40 -- 5.00 -- -- 47 5.25 6.0 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.2 0.44 VDD 7.5 1.47 360 2.0 2.5 0.50 VDD 8.0 1.6 400 -- 2.8 0.56 VDD 8.5 1.72 440 2.0 V V mV/g mV/g/V Hz % FSO nRMS nPSD nCLK -- -- -- -- 110 2.0 2.8 -- -- mVrms V/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 55 VSS 0.7 x VDD 30 -- 95 0.3 x VDD VDD 260 10 g V V A ms Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD .8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 50 -- 260 kHz Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- VSST -- -- 0.2 -- -- 300 -- VDD 0.3 100 -- ms V pF Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VXZ,YZ fPKG -- -- -- 10 5.0 -- % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (.01-1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * 77 -- -- 100 2.0 * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 35g. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-7 Freescale Semiconductor, Inc. MMA1200D Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 2. Transducer Physical Model Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. BASIC CONNECTIONS Figure 3. Equivalent Circuit Model Pinout Description SPECIAL FEATURES N/C Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. N/C N/C 2-8 ST VOUT STATUS VSS VDD 1 2 3 4 5 6 7 8 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C Motorola Sensor Device Data PCB Layout Pin Name 1 thru 3 -- Redundant VSS. Leave unconnected. 4 ST Logic input pin used to initiate self-test. 5 VOUT STATUS 7 8 VSS VDD 9 thru 13 Trim pins 14 thru 16 -- VDD Description Output voltage of the accelerometer. Logic output pin to indicate fault. The power supply ground. P1 ST VOUT VSS VDD P0 A/D IN R 1 k C 0.01 F C 0.1 F VRH The power supply input. C Used for factory trim. Leave unconnected. No internal connection. Leave unconnected. 4 ST 8 VDD VOUT C1 0.1 F 7 VSS 5 C 0.1 F VDD 0.1 F POWER SUPPLY STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F Figure 4. SOIC Accelerometer with Recommended Connection Diagram Motorola Sensor Device Data VSS Figure 5. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller 6 MMA1200D LOGIC INPUT STATUS ACCELEROMETER Pin No. 6 MMA1200D MICROCONTROLLER Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. NOTES: * Use a 0.1 F capacitor on VDD to decouple the power source. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-9 Freescale Semiconductor, Inc. MMA1200D Positive Acceleration Sensing Direction -Z Freescale Semiconductor, Inc... -Z +Z +Z Side View Side View Direction of Earth's gravity field.* Side View * When positioned as shown, the Earth's gravity will result in a positive 1g output ORDERING INFORMATION Device MMA1200D Temperature Range *40 to +85C Case No. Package Case 475-01 SOIC-16 MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct 2-10 footprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 0.380 in. 9.65 mm MMA1200D 0.050 in. 1.27 mm Freescale Semiconductor, Inc... 0.024 in. 0.610 mm 0.080 in. 2.03 mm Figure 6. Footprint SOIC-16 (Case 475-01) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-11 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA MMA1201P MMA2200W Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. Features * Integral Signal Conditioning Freescale Semiconductor, Inc... * Linear Output MMA1201P: Z AXIS SENSITIVITY MMA2200W: X AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 40g * Ratiometric Performance * 4th Order Bessel Filter Preserves Pulse Shape Integrity * Calibrated Self-test * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status 16 15 14 13 12 11 10 9 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability * Robust Design, High Shocks Survivability * Two Packaging Options Available: 1) Plastic DIP for Z Axis Sensing (MMA1201P) 2) Wingback for X Axis Sensing (MMA2200W) 1 2 3 4 5 6 7 8 DIP PACKAGE CASE 648C MMA1201P Typical Applications * Vibration Monitoring and Recording * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection 12 * Computer Mouse and Joysticks * Virtual Reality Input Devices 3 4 5 6 WB PACKAGE CASE 456 MMA2200W * Sports Diagnostic Devices and Systems SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR VST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 2-12 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1201P MMA2200W MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating Gpd 500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-13 Freescale Semiconductor, Inc. MMA1201P MMA2200W OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 4.0 40 -- 5.00 5.0 -- 38 5.25 6.0 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.2 0.44 VDD 47.5 9.3 360 1.0 2.5 0.50 VDD 50 10 400 -- 2.8 0.56 VDD 52.5 10.7 440 +1.0 V V mV/g mV/g/V Hz % FSO nRMS nPSD nCLK -- -- -- -- 110 2.0 3.5 -- -- mVrms V/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 20 VSS 0.7 x VDD 30 -- 30 0.3 x VDD VDD 300 10 g V V A ms Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD .8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 50 -- 260 kHz Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- 0.3 -- -- 0.2 -- -- 300 -- VDD 0.3 100 -- ms V pF Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VZX,YX fPKG -- -- -- 10 5.0 -- % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity (VDD = 5.0 V) Bandwidth Response Nonlinearity Noise RMS (.01-1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * -- -- -- 110 2.0 * * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-14 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1201P MMA2200W Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. BASIC CONNECTIONS Pinout Description for the Wingback Package Figure 2. Transducer Physical Model Figure 3. Equivalent Circuit Model 12 SPECIAL FEATURES Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag Motorola Sensor Device Data 3 4 5 6 Pin No. Pin Name Description 1 -- Leave unconnected or connect to signal ground 2 ST Logic input pin to initiate self test 3 VOUT Output voltage 4 Status Logic output pin to indicate fault 5 VSS Signal ground 6 VDD Supply voltage (5 V) -- Wings www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Support pins, internally connected to lead frame. Tie to VSS. 2-15 Freescale Semiconductor, Inc. MMA1201P MMA2200W 4 MMA2200W VDD LOGIC INPUT 2 ST 6 VDD VOUT C1 0.1 F 3 STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F 5 VSS Figure 4. Wingback Accelerometer with Recommended Connection Diagram VDD 6 MMA1201P LOGIC INPUT 4 ST 8 VDD VOUT C1 0.1 F 5 STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F 7 VSS Figure 5. DIP Accelerometer with Recommended Connection Diagram PCB Layout N/C 1 16 N/C N/C 2 15 N/C N/C 3 14 N/C ST 4 13 N/C VOUT 5 12 N/C STATUS 6 11 N/C VSS 7 10 N/C VDD 8 9 N/C ST VOUT VSS VDD P0 A/D IN R 1 k C 0.01 F C 0.1 F VRH C VSS C 0.1 F VDD 0.1 F POWER SUPPLY Figure 6. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller Pin No. Pin Name Description 1 -- Leave unconnected or connect to signal ground. 2 thru 3 -- No internal connection. Leave unconnected. 4 ST Logic input pin to initiate self test. 5 VOUT Output voltage 6 Status Logic output pin to indicate fault. 7 VSS Signal ground 8 VDD Supply voltage (5 V) 9 thru 13 Trim Pins 14 thru 16 -- 2-16 ACCELEROMETER Pinout Description for the DIP Package P1 MICROCONTROLLER Freescale Semiconductor, Inc... STATUS Used for factory trim. Leave unconnected. No internal connection. Leave unconnected. NOTES: * Use a 0.1 F capacitor on VDD to decouple the power source. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1201P MMA2200W Positive Acceleration Sensing Direction DIP PACKAGE WINGBACK PACKAGE 12 16 9 1 8 7 Freescale Semiconductor, Inc... 1 6 * * * When positioned as shown, the Earth's gravity will result in a positive 1g output Drilling Patterns WB PACKAGE DRILLING PATTERN .000 .090 .190 .290 .390 .490 .590 .680 .090 .049 2X .047 .033 6X .031 Measurement in inches ORDERING INFORMATION Device Temperature Range Case No. Package MMA1201P -40 to +85C Case 648C-04 Plastic DIP MMA2200W -40 to +85C Case 456-06 Plastic Wingback Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-17 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low G Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. Features * Integral Signal Conditioning MMA1220D MMA1220D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 8g Freescale Semiconductor, Inc... * Linear Output * Ratiometric Performance * 4th Order Bessel Filter Preserves Pulse Shape Integrity 16 * Calibrated Self-test 9 * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status 1 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 8 * Robust Design, High Shock Survivability 16 LEAD SOIC CASE 475 Typical Applications * Vibration Monitoring and Recording * Appliance Control * Mechanical Bearing Monitoring Pin Assignment * Computer Hard Drive Protection N/C * Virtual Reality Input Devices N/C ST * Sports Diagnostic Devices and Systems ORDERING INFORMATION Device Temperature Range MMA1220D -40 to +85C Case No. Package Case 475-01 SOIC-16 16 15 14 13 12 11 10 1 2 3 4 5 6 7 8 N/C * Computer Mouse and Joysticks VOUT STATUS VSS VDD 9 N/C N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 2-18 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1220D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating Gpd 1500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-19 Freescale Semiconductor, Inc. MMA1220D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (10 Hz - 1 kHz) Clock Noise (without RC load on output)(6) Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 3.0 40 -- 5.00 5.0 -- 8.0 5.25 6.0 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.25 0.45 VDD 237.5 46.5 150 1.0 2.5 0.50 VDD 250 50 250 -- 2.75 0.55 VDD 262.5 53.5 350 +3.0 V V mV/g mV/g/V Hz % FSO nRMS nCLK -- -- -- 2.0 6.0 -- mVrms mVpk 0.3 VDD 0.3 VDD VDD 200 10 V V V A ms DVST * * VIL VIH IIN tST 0.2 VDD VSS 0.7 VDD 50 -- Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD 0.8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 50 -- 260 kHz tDELAY VFSO CL ZO -- VSS+0.25 -- -- 2.0 -- -- 300 -- VDD 0.25 100 -- * ms V pF VXZ,YZ fPKG -- -- -- 10 5.0 -- % FSO kHz Clock Monitor Fail Detection Frequency Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance Mechanical Characteristics Transverse Sensitivity(11) Package Resonance * * -- -- -- 100 2.0 * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g, 100 Hz. Sensitivity limits apply to 0 Hz acceleration. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-20 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 2. Transducer Physical Model Motorola Sensor Device Data Figure 3. Equivalent Circuit Model MMA1220D SPECIAL FEATURES Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-21 Freescale Semiconductor, Inc. MMA1220D PCB Layout BASIC CONNECTIONS Pinout Description ST VOUT STATUS Freescale Semiconductor, Inc... VSS VDD N/C 9 N/C ACCELEROMETER N/C N/C 16 15 14 13 12 11 10 N/C N/C N/C N/C N/C N/C Description 1 thru 3 VSS Redundant connections to the internal VSS and may be left unconnected. 4 ST Logic input pin used to initiate self- test. 5 VOUT STATUS Output voltage of the accelerometer. 8 9 thru 13 Trim pins Used for factory trim. Leave unconnected. 14 thru 16 -- No internal connection. Leave unconnected. 8 VDD 7 VSS C 0.1 F VRH C 0.1 F VDD 0.1 F Figure 5. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller 6 VOUT 5 * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F Figure 4. SOIC Accelerometer with Recommended Connection Diagram 2-22 C 0.01 F * Use a 0.1 F capacitor on VDD to decouple the power source. The power supply input. 4 ST C1 0.1 F VDD 1 k VSS NOTES: The power supply ground. MMA1220D LOGIC INPUT VSS A/D IN R Logic output pin used to indicate fault. VSS VDD VDD VOUT P0 POWER SUPPLY Pin Name 7 ST C Pin No. 6 P1 MICROCONTROLLER 1 2 3 4 5 6 7 8 N/C STATUS * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1220D ACCELERATION SENSING DIRECTIONS DYNAMIC ACCELERATION N/C N/C N/C +g [ VOUT > 2.75 ] ST VOUT STATUS VSS VDD 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C Freescale Semiconductor, Inc... 16-Pin SOIC Package -g N/C pins are recommended to be left FLOATING [ VOUT < 2.75 ] STATIC ACCELERATION Direction of Earth's gravity field.* +1g VOUT = 2.75V 0g 0g VOUT = 2.50V VOUT = 2.50V -1g VOUT = 2.25V * When positioned as shown, the Earth's gravity will result in a positive 1g output Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-23 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low G Micromachined Accelerometer MMA1250D The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. MMA1250D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 5g Features * Integral Signal Conditioning * Linear Output Freescale Semiconductor, Inc... * 2nd Order Bessel Filter * Calibrated Self-test * EPROM Parity Check Status 16 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 9 * Robust Design, High Shock Survivability 1 Typical Applications 8 * Vibration Monitoring and Recording 16 LEAD SOIC CASE 475 * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection * Computer Mouse and Joysticks Pin Assignment * Virtual Reality Input Devices VSS VOUT ORDERING INFORMATION Device Temperature Range MMA1250D -40 to +105C Case No. Package Case 475-01 SOIC-16 16 15 14 13 12 11 10 1 2 3 4 5 6 7 8 VSS VSS * Sports Diagnostic Devices and Systems STATUS VDD VSS ST 9 N/C N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP & GAIN VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 1 2-24 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1250D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating gpd 1500 g Unpowered Acceleration (all axes) gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Hdrop 1.2 m Tstg - 40 to +125 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-25 Freescale Semiconductor, Inc. MMA1250D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +105C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 1.1 40 -- * 5.00 2.1 -- 5 5.25 3.0 +105 -- V mA C g 2.25 2.0 380 370 42.5 1.0 2.5 2.5 400 400 50 -- 2.75 3.0 420 430.1 57.5 +1.0 V V mV/g mV/g Hz % FSO -- -- 2.0 700 4.0 -- mVrms g/Hz VIL VIH IIN tST 1.0 VSS 0.7 VDD 50 -- 1.25 -- -- 125 10 1.5 0.3 VDD VDD 300 25 V V V A ms VOL VOH -- VDD 0.8 -- -- 0.4 -- V V Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = -200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- VSS+0.25 -- -- -- -- -- 50 2.0 VDD 0.25 100 -- * ms V pF Mechanical Characteristics Transverse Sensitivity(11) VXZ,YZ -- -- 5.0 % FSO Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (TA = 25C, VDD = 5.0 V)(4) Zero g (VDD = 5.0 V) Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity (VDD = 5.0 V) Bandwidth Response Nonlinearity VOFF VOFF S S f -3dB NLOUT Noise RMS (0.1 Hz - 1.0 kHz) Spectral Density (RMS, 0.1 Hz - 1.0 kHz)(6) Self-Test Output Response (VDD = 5.0 V) Input Low Input High Input Loading(7) Response Time(8) nRMS nSD DVST Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = -100 A) * * * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.1 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. Sensitivity limits apply to 0 Hz acceleration. 6. At clock frequency 35 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-26 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. MMA1250D PRINCIPLE OF OPERATION SPECIAL FEATURES The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Filtering The Motorola accelerometers contain an onboard 2-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Acceleration Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever the following event occurs: Figure 2. Transducer Physical Model Motorola Sensor Device Data Figure 3. Equivalent Circuit Model * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-27 Freescale Semiconductor, Inc. MMA1250D PCB Layout BASIC CONNECTIONS VSS ST N/C 9 N/C STATUS ACCELEROMETER VOUT STATUS VDD 16 15 14 13 12 11 10 N/C N/C N/C N/C N/C N/C P1 ST VOUT VSS VDD P0 A/D IN R 1 k 0.1 F C C 0.1 F VRH C MICROCONTROLLER 1 2 3 4 5 6 7 8 VSS VSS VSS VSS C 0.1 F VDD 0.1 F Freescale Semiconductor, Inc... Figure 4. Pinout Description POWER SUPPLY Pin No. Pin Name Description 1 thru 3 VSS Redundant connections to the internal VSS and may be left unconnected. 4 VOUT STATUS 5 6 Output voltage of the accelerometer. Logic output pin used to indicate fault. 7 VDD VSS 8 ST 9 thru 13 Trim pins Used for factory trim. Leave unconnected. 14 thru 16 -- No internal connection. Leave unconnected. VDD C1 0.1 F The power supply input. The power supply ground. NOTES: Logic input pin used to initiate self- test. * Use a 0.1 F capacitor on VDD to decouple the power source. MMA1250D LOGIC INPUT 5 8 ST 1 2 3 6 VDD VSS VSS VSS 7 VSS VOUT 4 * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal VSS terminals shown in Figure 4. STATUS R1 1 k OUTPUT SIGNAL C2 0.1 F Figure 5. SOIC Accelerometer with Recommended Connection Diagram 2-28 Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller * Use an RC filter of 1 k and 0.1 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1250D ACCELERATION SENSING DIRECTIONS DYNAMIC ACCELERATION VSS VSS VSS +g VOUT STATUS VDD VSS ST 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C Freescale Semiconductor, Inc... 16-Pin SOIC Package N/C pins are recommended to be left FLOATING -g STATIC ACCELERATION Direction of Earth's gravity field.* +1g VOUT = 2.9V 0g 0g VOUT = 2.50V VOUT = 2.50V -1g VOUT = 2.1V * When positioned as shown, the Earth's gravity will result in a positive 1g output Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-29 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low G Micromachined Accelerometer MMA1260D The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. MMA1260D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 1.5g Features * Integral Signal Conditioning * Linear Output Freescale Semiconductor, Inc... * 2nd Order Bessel Filter * Calibrated Self-test * EPROM Parity Check Status 16 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 9 * Robust Design, High Shock Survivability 1 Typical Applications 8 * Vibration Monitoring and Recording 16 LEAD SOIC CASE 475 * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection * Computer Mouse and Joysticks Pin Assignment * Virtual Reality Input Devices VSS VOUT ORDERING INFORMATION Device Temperature Range MMA1260D -40 to +105C Case No. Package Case 475-01 SOIC-16 16 15 14 13 12 11 10 1 2 3 4 5 6 7 8 VSS VSS * Sports Diagnostic Devices and Systems STATUS VDD VSS ST 9 N/C N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP & GAIN VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 1 2-30 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1260D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating gpd 1500 g Unpowered Acceleration (all axes) gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Hdrop 1.2 m Tstg - 40 to +125 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-31 Freescale Semiconductor, Inc. MMA1260D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +105C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (TA = 25C, VDD = 5.0 V)(4) Zero g (VDD = 5.0 V) Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity (VDD = 5.0 V) Bandwidth Response Nonlinearity Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 1.1 40 -- * 5.00 2.2 -- 1.5 5.25 3.2 +105 -- V mA C g 2.25 2.2 1140 1110 40 1.0 2.5 2.5 1200 1200 50 -- 2.75 2.8 1260 1290 60 +1.0 V V mV/g mV/g Hz % FSO -- -- 5.0 500 9.0 -- mVrms g/Hz 0.9 0.3 VDD VDD 300 25 V V V A ms VOFF VOFF S S f -3dB NLOUT Noise RMS (0.1 Hz - 1.0 kHz) Spectral Density (RMS, 0.1 Hz - 1.0 kHz)(6) Self-Test Output Response (VDD = 5.0 V) Input Low Input High Input Loading(7) Response Time(8) nRMS nSD DVST * VIL VIH IIN tST 0.3 VSS 0.7 VDD 50 -- VOL VOH -- VDD 0.8 -- -- 0.4 -- V V Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = -200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- VSS+0.25 -- -- -- -- -- 50 2.0 VDD 0.25 100 -- * ms V pF Mechanical Characteristics Transverse Sensitivity(11) VXZ,YZ -- -- 5.0 % FSO Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = -100 A) * * 0.6 -- -- 125 10 * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.1 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. Sensitivity limits apply to 0 Hz acceleration. 6. At clock frequency 35 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-32 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. MMA1260D PRINCIPLE OF OPERATION SPECIAL FEATURES The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Filtering The Motorola accelerometers contain an onboard 2-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Acceleration Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever the following event occurs: Figure 2. Transducer Physical Model Motorola Sensor Device Data Figure 3. Equivalent Circuit Model * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-33 Freescale Semiconductor, Inc. MMA1260D PCB Layout BASIC CONNECTIONS VSS ST N/C 9 N/C STATUS ACCELEROMETER VOUT STATUS VDD 16 15 14 13 12 11 10 N/C N/C N/C N/C N/C N/C P1 ST VOUT VSS VDD P0 A/D IN R 1 k 0.1 F C C 0.1 F VRH C MICROCONTROLLER 1 2 3 4 5 6 7 8 VSS VSS VSS VSS C 0.1 F VDD 0.1 F Figure 4. Pinout Description Freescale Semiconductor, Inc... POWER SUPPLY Pin No. Pin Name Description 1 thru 3 VSS Redundant connections to the internal VSS and may be left unconnected. 4 VOUT STATUS 5 6 7 VDD VSS 8 ST 9 thru 13 14 thru 16 VDD C1 0.1 F Output voltage of the accelerometer. Logic output pin used to indicate fault. The power supply input. The power supply ground. NOTES: Logic input pin used to initiate self- test. * Use a 0.1 F capacitor on VDD to decouple the power source. Trim pins Used for factory trim. Leave unconnected. -- No internal connection. Leave unconnected. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. MMA1260D LOGIC INPUT 5 8 ST 1 2 3 6 VDD VSS VSS VSS 7 VSS VOUT 4 STATUS R1 1 k OUTPUT SIGNAL C2 0.1 F Figure 5. SOIC Accelerometer with Recommended Connection Diagram 2-34 Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal VSS terminals shown in Figure 4. * Use an RC filter of 1 k and 0.1 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1260D ACCELERATION SENSING DIRECTIONS DYNAMIC ACCELERATION VSS VSS VSS +g VOUT STATUS VDD VSS ST 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C Freescale Semiconductor, Inc... 16-Pin SOIC Package N/C pins are recommended to be left FLOATING -g STATIC ACCELERATION Direction of Earth's gravity field.* +1g VOUT = 3.7V 0g 0g VOUT = 2.50V VOUT = 2.50V -1g VOUT = 1.3V * When positioned as shown, the Earth's gravity will result in a positive 1g output Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-35 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low G Micromachined Accelerometer MMA1270D The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. MMA1270D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 2.5g Features * Integral Signal Conditioning * Linear Output Freescale Semiconductor, Inc... * 2nd Order Bessel Filter * Calibrated Self-test * EPROM Parity Check Status 16 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 9 * Robust Design, High Shock Survivability 1 Typical Applications 8 * Vibration Monitoring and Recording 16 LEAD SOIC CASE 475 * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection * Computer Mouse and Joysticks Pin Assignment * Virtual Reality Input Devices VSS VOUT ORDERING INFORMATION Device Temperature Range MMA1270D -40 to +105C Case No. Package Case 475-01 SOIC-16 16 15 14 13 12 11 10 1 2 3 4 5 6 7 8 VSS VSS * Sports Diagnostic Devices and Systems STATUS VDD VSS ST 9 N/C N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP & GAIN VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 1 2-36 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1270D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating gpd 1500 g Unpowered Acceleration (all axes) gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Hdrop 1.2 m Tstg - 40 to +125 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-37 Freescale Semiconductor, Inc. MMA1270D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +105C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 1.1 40 -- * 5.00 2.1 -- 2.5 5.25 3.0 +105 -- V mA C g VOFF VOFF S S f -3dB NLOUT 2.25 2.2 712.5 693.8 40 1.0 2.5 2.5 750 750 50 -- 2.75 2.8 787.5 806.3 60 +1.0 V V mV/g mV/g Hz % FSO nRMS nSD -- -- 3.5 700 6.5 -- mVrms g/Hz VIL VIH IIN tST 0.9 VSS 0.7 VDD 50 -- 1.25 -- -- 125 10 1.6 0.3 VDD VDD 300 25 V V V A ms VOL VOH -- VDD 0.8 -- -- 0.4 -- V V Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = -200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- VSS+0.25 -- -- -- -- -- 50 2.0 VDD 0.25 100 -- * ms V pF Mechanical Characteristics Transverse Sensitivity(11) VXZ,YZ -- -- 5.0 % FSO Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (TA = 25C, VDD = 5.0 V)(4) Zero g (VDD = 5.0 V) Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity(VDD = 5.0 V) Bandwidth Response Nonlinearity Noise RMS (0.1 Hz - 1.0 kHz) Spectral Density (RMS, 0.1 Hz - 1.0 kHz)(6) Self-Test Output Response (VDD = 5.0 V) Input Low Input High Input Loading(7) Response Time(8) DVST Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = -100 A) * * * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.1 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. Sensitivity limits apply to 0 Hz acceleration. 6. At clock frequency 35 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-38 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. MMA1270D PRINCIPLE OF OPERATION SPECIAL FEATURES The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Filtering The Motorola accelerometers contain an onboard 2-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Acceleration Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever the following event occurs: Figure 2. Transducer Physical Model Motorola Sensor Device Data Figure 3. Equivalent Circuit Model * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-39 Freescale Semiconductor, Inc. MMA1270D PCB Layout BASIC CONNECTIONS VSS ST N/C 9 N/C STATUS ACCELEROMETER VOUT STATUS VDD 16 15 14 13 12 11 10 N/C N/C N/C N/C N/C N/C P1 ST VOUT VSS VDD P0 A/D IN R 1 k 0.1 F C C 0.1 F VRH C MICROCONTROLLER 1 2 3 4 5 6 7 8 VSS VSS VSS VSS C 0.1 F VDD 0.1 F Figure 4. Pinout Description Freescale Semiconductor, Inc... POWER SUPPLY Pin No. Pin Name Description 1 thru 3 VSS Redundant connections to the internal VSS and may be left unconnected. 4 VOUT STATUS 5 6 7 VDD VSS 8 ST 9 thru 13 14 thru 16 VDD C1 0.1 F Output voltage of the accelerometer. Logic output pin used to indicate fault. The power supply input. The power supply ground. NOTES: Logic input pin used to initiate self- test. * Use a 0.1 F capacitor on VDD to decouple the power source. Trim pins Used for factory trim. Leave unconnected. -- No internal connection. Leave unconnected. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. MMA1270D LOGIC INPUT 5 8 ST 1 2 3 6 VDD VSS VSS VSS 7 VSS VOUT 4 * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all internal VSS terminals shown in Figure 4. STATUS R1 1 k OUTPUT SIGNAL C2 0.1 F Figure 5. SOIC Accelerometer with Recommended Connection Diagram 2-40 Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller * Use an RC filter of 1 k and 0.1 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA1270D ACCELERATION SENSING DIRECTIONS DYNAMIC ACCELERATION VSS VSS VSS +g VOUT STATUS VDD VSS ST 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C Freescale Semiconductor, Inc... 16-Pin SOIC Package N/C pins are recommended to be left FLOATING -g STATIC ACCELERATION Direction of Earth's gravity field.* +1g VOUT = 3.25V 0g 0g VOUT = 2.50V VOUT = 2.50V -1g VOUT = 1.75V * When positioned as shown, the Earth's gravity will result in a positive 1g output Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-41 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA MMA2201D Surface Mount Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. Features MMA2201D: X AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 40g Freescale Semiconductor, Inc... * Integral Signal Conditioning * Linear Output * Ratiometric Performance 16 * 4th Order Bessel Filter Preserves Pulse Shape Integrity 9 * Calibrated Self-test 1 * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status 8 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 16 LEAD SOIC CASE 475 * Robust Design, High Shocks Survivability Typical Applications * Vibration Monitoring and Recording * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection * Computer Mouse and Joysticks * Virtual Reality Input Devices * Sports Diagnostic Devices and Systems SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR VST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 2-42 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA2201D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating Gpd 500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-43 Freescale Semiconductor, Inc. MMA2201D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 4.0 40 -- 5.00 5.0 -- 38 5.25 6.0 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.3 0.44 VDD 47.5 9.3 360 1.0 2.5 0.50 VDD 50 10 400 -- 2.7 0.56 VDD 52.5 10.7 440 +1.0 V V mV/g mV/g/V Hz % FSO nRMS nPSD nCLK -- -- -- -- 110 2.0 2.8 -- -- mVrms V/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 10 VSS 0.7 x VDD 30 -- 14 0.3 x VDD VDD 300 10 g V V A ms Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD .8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 150 -- 400 kHz Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- 0.3 -- -- 0.2 -- -- 300 -- VDD 0.3 100 -- ms V pF Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VZX,YX fPKG -- -- -- 10 5.0 -- % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (.01-1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * 12 -- -- 110 2.0 * * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-44 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 2. Transducer Physical Model Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. BASIC CONNECTIONS Figure 3. Equivalent Circuit Model Pinout Description SPECIAL FEATURES N/C Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. N/C N/C Motorola Sensor Device Data MMA2201D ST VOUT N/C VSS VDD www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C 2-45 Freescale Semiconductor, Inc. PCB Layout Pin Name 1 thru 3 -- No internal connection. Leave unconnected. 4 ST Logic input pin used to initiate self-test. 5 VOUT 6 -- Description Output voltage of the accelerometer. No internal connection. Leave unconnected. 7 VSS The power supply ground. 8 VDD The power supply input. 9 thru 13 Trim pins 14 thru 16 -- VDD No internal connection. Leave unconnected. LOGIC INPUT 6 4 ST 8 VDD C1 0.1 F 7 VSS VOUT 5 STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F Figure 4. SOIC Accelerometer with Recommended Connection Diagram 2-46 P1 ST VOUT VSS VDD P0 A/D IN R 1 k C 0.01 F C 0.1 F VRH C Used for factory trim. Leave unconnected. MMA2201D STATUS ACCELEROMETER Pin No. MICROCONTROLLER Freescale Semiconductor, Inc... MMA2201D VSS C 0.1 F VDD 0.1 F POWER SUPPLY Figure 5. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller NOTES: * Use a 0.1 F capacitor on VDD to decouple the power source. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA2201D Positive Acceleration Sensing Direction N/C -X N/C N/C AXIS ORIENTATION (ACCELERATION FORCE VECTOR) SELF TEST XOUT N/C +X VSS VDD 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C 16-Pin SOIC Package Freescale Semiconductor, Inc... N/C pins are recommended to be left FLOATING 8 7 6 5 4 3 2 1 Direction of Earth's gravity field.* 9 10 11 12 13 14 15 16 * When positioned as shown, the Earth's gravity will result in a positive 1g output ORDERING INFORMATION Device MMA2201D Temperature Range *40 to +85C Motorola Sensor Device Data Case No. Case 475-01 Package SOIC-16 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-47 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Surface Mount Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. Features * Integral Signal Conditioning MMA2202D MMA2202D: X AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 50g Freescale Semiconductor, Inc... * Linear Output * Ratiometric Performance * 4th Order Bessel Filter Preserves Pulse Shape Integrity 16 * Calibrated Self-test * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status 9 1 * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 8 * Robust Design, High Shocks Survivability 16 LEAD SOIC CASE 475 Typical Applications * Vibration Monitoring and Recording * Impact Monitoring * Appliance Control Pin Assignment * Mechanical Bearing Monitoring * Computer Hard Drive Protection N/C * Computer Mouse and Joysticks N/C * Virtual Reality Input Devices N/C ST * Sports Diagnostic Devices and Systems 1 2 3 4 5 6 7 8 VOUT STATUS VSS VDD 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G-CELL SENSOR ST SELF-TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 2-48 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA2202D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating Gpd 500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over Motorola Sensor Device Data 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-49 Freescale Semiconductor, Inc. MMA2202D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 4.0 40 -- 5.00 5.0 -- 47 5.25 6.0 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.3 0.44 VDD 37 7.4 360 1.0 2.5 0.50 VDD 40 8 400 -- 2.7 0.56 VDD 43 8.6 440 +1.0 V V mV/g mV/g/V Hz % FSO nRMS nPSD nCLK -- -- -- -- 110 2.0 2.8 -- -- mVrms V/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 10 VSS 0.7 x VDD 30 -- 14 0.3 x VDD VDD 300 10 g V V A ms Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD .8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 150 -- 400 kHz Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- 0.3 -- -- 0.2 -- -- 300 -- VDD 0.3 100 -- ms V pF Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VZX,YX fPKG -- -- -- 10 5.0 -- % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (.01-1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * 12 -- -- 110 2.0 * * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ 2-50 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 2. Transducer Physical Model Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. BASIC CONNECTIONS Figure 3. Equivalent Circuit Model Pinout Description SPECIAL FEATURES N/C Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. N/C N/C Motorola Sensor Device Data MMA2202D ST VOUT STATUS VSS VDD www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C 2-51 Freescale Semiconductor, Inc. PCB Layout Pin Name 1 thru 3 -- No internal connection. Leave unconnected. 4 ST Logic input pin used to initiate self-test. 5 VOUT 6 STATUS 7 8 VSS VDD 9 thru 13 Trim pins 14 thru 16 -- VDD Description Output voltage of the accelerometer. Logic output pin to indicate fault. The power supply ground. The power supply input. 8 VDD 7 VSS VOUT VSS VDD P0 A/D IN R 1 k C 0.01 F C 0.1 F VRH VOUT 6 5 VSS C 0.1 F VDD 0.1 F POWER SUPPLY Figure 5. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller STATUS R1 1 k OUTPUT SIGNAL C2 0.01 F Figure 4. SOIC Accelerometer with Recommended Connection Diagram 2-52 ST C No internal connection. Leave unconnected. 4 ST C1 0.1 F P1 Used for factory trim. Leave unconnected. MMA2202D LOGIC INPUT STATUS ACCELEROMETER Pin No. MICROCONTROLLER Freescale Semiconductor, Inc... MMA2202D NOTES: * Use a 0.1 F capacitor on VDD to decouple the power source. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA2202D Positive Acceleration Sensing Direction 1 2 3 4 5 6 7 8 -X 16 15 14 13 12 11 10 +X 9 16-Pin SOIC Package Freescale Semiconductor, Inc... N/C pins are recommended to be left FLOATING Top View 8 7 6 5 4 3 2 1 Direction of Earth's gravity field.* 9 10 11 12 13 14 15 16 Front View Side View * When positioned as shown, the Earth's gravity will result in a positive 1g output ORDERING INFORMATION Device MMA2202D Temperature Range *40 to +85C Case No. Package Case 475-01 SOIC-16 MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct Motorola Sensor Device Data footprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-53 MMA2202D Freescale Semiconductor, Inc. 0.380 in. 9.65 mm 0.050 in. 1.27 mm Freescale Semiconductor, Inc... 0.024 in. 0.610 mm 0.080 in. 2.03 mm Figure 6. Footprint SOIC-16 (Case 475-01) 2-54 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Surface Mount Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. Features MMA3201D MMA3201D: X-Y AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 40g * Integral Signal Conditioning Freescale Semiconductor, Inc... * Linear Output * Ratiometric Performance 20 * 4th Order Bessel Filter Preserves Pulse Shape Integrity * Calibrated Self-test 11 1 * Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status * Transducer Hermetically Sealed at Wafer Level for Superior Reliability 10 * Robust Design, High Shocks Survivability 20 LEAD SOIC CASE 475A Typical Applications * Vibration Monitoring and Recording * Impact Monitoring * Appliance Control Pin Assignment * Mechanical Bearing Monitoring * Computer Hard Drive Protection N/C * Computer Mouse and Joysticks N/C N/C * Virtual Reality Input Devices N/C ST XOUT * Sports Diagnostic Devices and Systems STATUS VSS VDD AVDD 1 2 3 4 5 6 7 8 20 19 18 17 16 15 14 N/C 13 N/C 9 10 12 N/C YOUT 11 N/C N/C N/C N/C N/C N/C SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM AVDD VDD G-CELL SENSOR INTEGRATOR GAIN FILTER TEMP COMP XOUT YOUT ST SELF-TEST CONTROL LOGIC & EPROM TRIM CIRCUITS OSCILLATOR CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-55 Freescale Semiconductor, Inc. MMA3201D MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Rating Symbol Value Unit Powered Acceleration (all axes) Gpd $200 Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD -0.3 to +7.0 V Ddrop 1.2 m Tstg - 40 to +105 C Drop Test(1) Storage Temperature Range g NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over 2-56 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MMA3201D OPERATING CHARACTERISTICS (Unless otherwise noted: -40C v TA v +85C, 4.75 v VDD v 5.25, X and Y Channels, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 6 40 -- 5.00 8 -- 45 5.25 10 +85 -- V mA C g VOFF VOFF,V S SV f -3dB NLOUT 2.2 0.44 VDD 45 9 360 1.0 2.5 0.50 VDD 50 10 400 -- 2.8 0.56 VDD 55 11 440 +1.0 V V mV/g mV/g/V Hz % FSO nRMS nPSD nCLK -- -- -- -- 110 2.0 2.8 -- -- mVrms V/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 9.6 VSS 0.7 x VDD 30 -- 14.4 0.3 x VDD VDD 300 -- g V V A ms Status(12)(13) Output Low (Iload = 100 A) Output High (Iload = 100 A) VOL VOH -- VDD .8 -- -- 0.4 -- V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 50 -- 260 kHz Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO -- 0.3 -- -- 0.2 -- -- 300 -- VDD 0.3 100 -- ms V pF Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VZX,YX fPKG -- -- -- 10 5.0 -- % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (.01-1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * * 12 -- -- 110 2.0 * * * NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g. 6. At clock frequency 70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the device's ability to reject an acceleration applied 90 from the true axis of sensitivity. 12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high. 13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self-test, unless a fault condition continues to exist. * ^ Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-57 Freescale Semiconductor, Inc. MMA3201D Freescale Semiconductor, Inc... PRINCIPLE OF OPERATION The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g-cell plates form two back-to-back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 2. Transducer Physical Model Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Status Motorola accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: * Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold * Clock oscillator falls below the clock monitor minimum frequency * Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self- test input pin, unless one (or more) of the fault conditions continues to exist. BASIC CONNECTIONS Figure 3. Equivalent Circuit Model Pinout Description N/C N/C SPECIAL FEATURES N/C Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. N/C ST 2-58 XOUT STATUS VSS VDD AVDD 1 2 3 4 5 6 7 8 20 19 18 17 16 15 14 9 10 12 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 13 11 N/C N/C N/C N/C N/C N/C N/C N/C N/C YOUT Motorola Sensor Device Data Freescale Semiconductor, Inc. 1 thru 3 -- Redundant Vss. Leave unconnected. 4 -- No internal connection. Leave unconnected. ST 6 XOUT 7 STATUS 8 VSS VDD 10 Logic input pin used to initiate self-test. Output voltage of the accelerometer. X Direction. Logic output pin to indicate fault. YOUT VSS VDD R 1 k R 1 k A/D IN C 0.01 F A/D IN C 0.01 F C 0.1 F VRH C 11 12 thru 16 -- Used for factory trim. Leave unconnected. 17 thru 20 -- No internal connection. Leave unconnected. Output voltage of the accelerometer. Y Direction. MMA3201D 7 STATUS 5 ST 9 VDD C1 0.1 F P0 XOUT Power supply input. Power supply input (Analog). LOGIC INPUT P1 ST The power supply ground. AVDD YOUT VDD STATUS ACCELEROMETER Description R1 1 k XOUT 6 10 AVDD X OUTPUT SIGNAL C2 0.01 F 8 VSS YOUT 11 R2 1 k Y OUTPUT SIGNAL C3 0.01 F Figure 4. SOIC Accelerometer with Recommended Connection Diagram Motorola Sensor Device Data MICROCONTROLLER Pin Name 9 Freescale Semiconductor, Inc... PCB Layout Pin No. 5 MMA3201D VSS C 0.1 F VDD 0.1 F POWER SUPPLY Figure 5. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller NOTES: * Use a 0.1 F capacitor on VDD to decouple the power source. * Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 4. * Use an RC filter of 1 k and 0.01 F on the outputs of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-59 Freescale Semiconductor, Inc. MMA3201D Positive Acceleration Sensing Direction -Y Freescale Semiconductor, Inc... -X 1 2 3 4 5 6 7 8 20 19 18 17 16 15 14 9 10 12 +X 13 11 +Y 20-Pin SOIC Package N/C pins are recommended to be left FLOATING Top View 10 9 8 7 6 5 4 3 2 1 Direction of Earth's gravity field.* 11 12 13 14 15 16 17 18 19 20 Front View Side View * When positioned as shown, the Earth's gravity will result in a positive 1g output ORDERING INFORMATION Device MMA3201D Temperature Range *40 to +85C Case No. Case 475A-01 Package SOIC-20 MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS 2-60 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct Freescale Semiconductor, Inc... 0.380 in. 9.65 mm MMA3201D footprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.050 in. 1.27 mm 0.024 in. 0.610 mm 0.080 in. 2.03 mm Figure 6. Footprint SOIC-20 (Case 475A-01) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-61 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Application Considerations for a Switched Capacitor Accelerometer AN1559 By Wayne Chavez Freescale Semiconductor, Inc... INTRODUCTION Today's low cost accelerometers are highly integrated devices employing features such as signal conditioning, filtering, offset compensation and self test. Combining this feature set with economical plastic packaging requires that the signal conditioning circuitry be as small as possible. One approach is to implement sampled data system and switched capacitor techniques as in the Motorola accelerometer. As in all sampled data systems, precautions should be taken to avoid signal aliasing errors. This application note describes the Motorola accelerometer and how signal aliasing can be introduced and more importantly minimized. BACKGROUND What is aliasing? Simply put, aliasing is the effect of sampling a signal at an insufficient rate, thus creating another signal at a frequency that is the difference between the original signal frequency and the sampling rate. A graphical explanation of aliasing is offered in Figure 1. In this figure, the upper trace shows a 50 kHz sinusoidal waveform. Note that when sampled at a 45 kHz rate, denoted by the boxes, a sinusoidal pattern is formed. Lowpass filtering the sampled points, to create a continuous signal, produces the 5 kHz waveform shown in Figure 1 (lower). (The phase shift in the lower figure is due to the low-pass filter). Aliased signals, like the one in Figure 1 (lower) are often unintentionally produced. Signal processing techniques are well understood and sampling rates are chosen appropriately (i.e. Nyquist criteria). However, the assumption is that the signals of interest are well characterized and have a limited bandwidth. This assumption is not always true, as in the case of wideband noise. Figure 1. Aliased Signals REV 1 2-62 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data AN1559 DEMONSTRATION OF ALIASING Under zero acceleration conditions a 100 mVrms signal was injected onto the power supply line of 5.0 Vdc. The frequency of the injected signal was tuned in to produce an alias in the accelerometer's passband. Figures 3 and 4 show the difference in output when a high frequency signal is not and is present on the VCC pin of the accelerometer. 1.0E+0 Vout 1.0E-1 1.0E-2 Vrms Given the brief example on how aliasing can occur, how does the accelerometer relate to aliasing? To answer this question, a brief summary on how the accelerometer works is in order. The accelerometer is a two chip acceleration sensing solution. The first chip is the acceleration transducer, termed G-Cell, constructed by Micro Electro-Mechanical Systems (MEMS) technology. The G-Cell is a two capacitor element where the capacitors are in series and share a common center plate. The deflection in the center plate changes the capacitance of each capacitor which is measured by the second chip, termed control chip. The control chip performs the signal conditioning (amplification, filtering, offset level shift) function in the system. This chip measures the G-Cell output using switched capacitor techniques. By the nature of switched cap techniques, the system is a sampled data system operating at sampling frequency fs. The filter is switched capacitor, 4-pole Bessel implementation with a -3 dB frequency of 400 Hz. As a sampled data system, the accelerometer is not immune to signal aliasing. However, given the accelerometer's internal filter, aliased signals will only appear in the output passband when input signals are in the range | n* fs - fsignal | fBW. Where fs is the sampling rate, fSignal is the input signal frequency, fBW is the filter bandwidth and n is a positive integer to account for all harmonics. The graphical representation is shown in Figure 2. The bounds can be extended beyond fBW to ensure an alias free output. SAMPLING FREQUENCY 1.0E-3 1.0E-4 1.0E-5 1.0E-6 1.0E-7 41.0 41.2 41.4 41.6 FREQUENCY (kHz) 41.8 42.0 (a) 1.0E+0 VCC 1.0E-1 KEEP OUT ZONE Vrms 1.0E-2 1.0E-3 SAMPLING FREQUENCY 1.0E-4 1.0E-5 1.0E-6 n*fs - fBW n*fs n*fs + fBW 1.0E-7 41.0 Hz 41.2 Figure 2. Input signal frequency range where a signal will be produced in the output passband. 41.4 41.6 FREQUENCY (kHz) 41.8 42.0 (b) 1.0E+0 ACCELEROMETER INPUT SIGNALS The accelerometer is a ratiometric electro-mechanical transducer. Therefore, the input signals to the device are the acceleration and the input power source. The acceleration input is limited in frequency bandwidth by the geometry of the sensing, packaging, and mounting structures that define the resonant frequency and response. This response is in the range of 10 kHz, however, the practical range is less than 600 Hz for most mechanical systems. Therefore, aliasing an acceleration signal is unlikely. The power input signal is ideally dc. However, depending on the application system architecture, the power supply line can be riddled with high frequency components. For example, dc to dc converters can operate with switching frequencies between 20 kHz and 200 kHz. This range encompasses the sampling rate of the accelerometer and point to the power source as the culprit in producing aliased signal. Motorola Sensor Device Data Vout 1.0E-1 1.0E-2 Vrms Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 1.0E-3 1.0E-4 1.0E-5 1.0E-6 0 200 400 600 FREQUENCY (Hz) 800 1000 (c) Figure 3. Normal Waveforms www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-63 Freescale Semiconductor, Inc. AN1559 Points to note: 1.0E+0 1.0E-1 * Under clean dc bias, Vout and VCC, Figures 3a and 3b have a signal component at the sampling rate. This is due to switched capacitor currents coupling through finite power supply source impedances and PCB paracitics. Vout INJECTED SIGNAL FREQUENCY Vrms 1.0E-2 SAMPLING FREQUENCY 1.0E-3 * The low frequency output spectrum, Figure 3c, displays the internal lowpass filter characteristics. (The filter and sampling characteristics are sometimes useful in system debugging.) 1.0E-4 1.0E-5 1.0E-6 41.0 41.2 41.4 41.6 FREQUENCY (kHz) 41.8 42.0 * As a result of sampling, the output waveform of Figure 4c is produced where the injected high frequency signal has now produced a signal in the passband. 1.0E+0 VCC 1.0E-1 INJECTED SIGNAL FREQUENCY Vrms 1.0E-2 * Harmonics of the aliased signal in the pass band are also shown in Figure 4c. 1.0E-3 * Aliased signals in the passband will be amplified versions of the injected signals. This is due to the signal conditioning circuitry in the accelerometer that includes gain. SAMPLING FREQUENCY 1.0E-4 1.0E-5 ALIASING AVOIDANCE KEYS 1.0E-6 1.0E-7 41.0 41.2 41.4 41.6 FREQUENCY (kHz) 41.8 42.0 1.0E+0 Vout 1.0E-1 1.0E-2 * Proper bias decoupling will aid in noise reduction from other sources. With dense surface mount PCB assemblies, it is often difficult to place and route decoupling components. However, the accelerometer is not like a typical logic device. A little extra effort on decoupling goes a long way. 1.0E-3 1.0E-4 1.0E-5 1.0E-6 0 200 400 600 FREQUENCY (Hz) 800 (c) Figure 4. Aliasing Comparison 2-64 * Use a linear regulated power source when feasible. Linear regulators have excellent power supply rejection offering a stable dc source. * If using a switching power supply, ensure that the switching frequency is not close to the accelerometer sampling frequency or its harmonics. Noting that the accelerometer will gain the aliasing signal, it is desirable to keep frequencies at least 4 kHz away from the sampling frequency and its harmonics. 4 kHz is one decade from the -3 dB frequency, therefore any signals will be sufficiently attenuated by the internal 4-pole lowpass filter. (b) Vrms Freescale Semiconductor, Inc... (a) * When an ac component is superimposed onto VCC near the sampling frequency, as shown in Figure 4b, the output will contain the original signal plus a mirrored signal about the sampling frequency, shown in Figure 4a. Signals on the VCC line will appear at the output due to the ratiometric characteristic of the accelerometer and will be one half the amplitude. 1000 * Good PCB layout practices should always be followed. Proper system grounding is essential. Parasitic capacitance and inductance could prove to be troublesome, particularly during EMC testing. Signal harmonics and sub-harmonics play a significant role in introducing aliased signals. Clean layouts minimize the effects of parasitics and thus signal harmonics and sub-harmonics. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1611 Impact Measurement Using Accelerometers Prepared by: C.S. Chua Sensor Application Engineering Singapore, A/P Freescale Semiconductor, Inc... INTRODUCTION This application note describes the concept of measuring impact of an object using an accelerometer, microcontroller hardware/software and a liquid crystal display. Due to the wide frequency response of the accelerometer from d.c. to 400Hz, the device is able to measure both the static acceleration from the Earth's gravity and the shock or vibration from an impact. This design uses a 40G accelerometer (Motorola P/N: MMA2200W) yields a minimum acceleration range of -40G to +40G. -q +q MMA2200W SIDE VIEW PCB 1.0 g FRONT VIEW Figure 1. Orientation of Accelerometer REV 2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-65 Freescale Semiconductor, Inc. AN1611 CONCEPT OF IMPACT MEASUREMENT During an impact, the accelerometer will be oriented as shown in Figure 1 to measure the deceleration experienced by the object from dc to 400Hz. Normally, the peak impact pulse is in the order of a few miniseconds. Figure 2 shows a typical crash waveform of a toy car having a stiff bumper. 50 PEAK IMPACT PULSE 40 30 DECELERATION (G) Freescale Semiconductor, Inc... 20 10 0 -10 -20 -30 -40 0 10 20 30 40 50 60 TIME (ms) Figure 2. Typical Crash Pattern 2-66 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. HARDWARE DESCRIPTION AND OPERATION Since MMA2200W is fully signal-conditioned by its internal op-amp and temperature compensation, the output of the accelerometer can be directly interfaced with an analog-to- digital (A/D) converter for digitization. A filter consists of one RC network should be added if the connection between the output of the accelerometer and the A/D converter is a long track or cable. This stray capacitance may change the position of the internal pole which would drive the output amplifier of the accelerometer into oscillation or unstability. In this design, the cut-off frequency is chosen to be 15.9 kHz which also acts as an anti-alias filter for the A/D converter. The 3dB frequency can be approximated by the following equation. Freescale Semiconductor, Inc... f -3dB 1 + 2RC Referring to the schematic, Figure 3, the MMA2200W accelerometer is connected to PORT D bit 5 and the output of the amplifier is connected to PORT D bit 6 of the microcontroller. This port is an input to the on-chip 8-bit analog-to- digital (A/D) converter. Typically, the accelerometer provides a signal output to the microprocessor of approximately 0.3 Vdc at -55g to 4.7 Vdc at +55g of acceleration. However, Motorola only guarantees the accuracy within 40g range. Using the same reference voltage for the A/D converter and accelerometer minimizes the number of additional components, but does sacrifice resolution. The resolution is defined by the following: count 255 The count at 0g = [2.5/5] 255 128 The count at +25g = [3.5/5] 255 179 The count at -25g = [1.5/5] 255 77 Therefore the resolution 0.5g/count The output of the accelerometer is ratiometric to the voltage applied to it. The accelerometer and the reference voltages are connected to a common supply; this yields a system that is ratiometric. By nature of this ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. The liquid crystal display (LCD) is directly driven from I/O ports A, B, and C on the microcontroller. The operation of a Motorola Sensor Device Data LCD requires that the data and backplane (BP) pins must be driven by an alternating signal. This function is provided by a software routine that toggles the data and backplane at approximately a 30 Hz rate. Other than the LCD, one light emitting diode (LED) are connected to the pulse length converter (PLM) of the microcontroller. This LED will lights up for 3 seconds when an impact greater or equal to 7g is detected. The microcontroller section of the system requires certain support hardware to allow it to function. The MC34064P-5 provides an undervoltage sense function which is used to reset the microprocessor at system power-up. The 4 MHz crystal provides the external portion of the oscillator function for clocking the microcontroller and provides a stable base for time bases functions, for instance calculation of pulse rate. SOFTWARE DESCRIPTION Upon power-up the system, the LCD will display CAL for approximately 4 seconds. During this period, the output of the accelerometer are sampled and averaged to obtain the zero offset voltage or zero acceleration. This value will be saved in the RAM which is used by the equation below to calculate the impact in term of g-force. One point to note is that the accelerometer should remain stationary during the zero calibration. Impact + Vout 5 AN1611 + [count * countoffset ] resolution In this software program, the output of the accelerometer is calculated every 650s. During an impact, the peak deceleration is measured and displayed on the LCD for 3 seconds before resetting it to zero. In the mean time, if a higher impact is detected, the value on the LCD will be updated accordingly. However, when a low g is detected (e.g. 1.0g), the value will not be displayed. Instead, more samples will be taken for further averaging to eliminate the random noise and high frequency component. Due to the fact that tilting is a low g and low frequency signal, large number of sampling is preferred to avoid unstable display. Moreover, the display value is not hold for 3 seconds as in the case of an impact. Figure 4 is a flowchart for the program that controls the system. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-67 Freescale Semiconductor, Inc. AN1611 MC34064 +5.0 V G4 F4 A4 B4 C4 D4 E4 1 L R1 LCD5657 Freescale Semiconductor, Inc... +5.0 V R5 R6 R7 JUMPER OPEN JUMPER 12 27 26 25 24 15 14 13 16 23 22 21 20 19 18 17 DP1 G1 F1 A1 4 B1 C1 D1 DP E1 3 4.7 k DP L +5.0 V 8 DP3 DP2 2 32 G2 G3 31 F2 DP E F F3 30 A2 A3 29 B2 D 1 G A B3 11 C2 C3 10 C B D3 D2 9 E2 E3 3 /RESET 28 L 40 BP 1 BP GND 37 36 35 34 7 6 5 INPUT 2 39 38 37 36 35 34 33 32 PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 31 30 29 28 27 26 25 24 PA0 PA1 PA2 PA3 PA4 PA5 PA6 PA7 8 7 VRH VRL 60 ROI TCAP1 TCAP2 PD0/AN0 PD1/AN1 PD2/AN2 PD3/AN3 PD4/AN4 PD5/AN5 PD6/AN6 PD7/AN7 14 13 12 11 9 5 4 3 PC0 PC1 PC2/ECLK PC3 PC4 PC5 PC6 PC7 49 48 47 46 45 44 43 42 PLMA PLMB 20 21 TDO SCLK 52 51 18 19 /RESET /IRQ OSC1 22 23 TCMP1 TCMP2 C3 MC68HC05B16CFN 2 1 4.0 MHz 10 M VDD 22 p 17 R2 X1 OSC2 C4 10 16 +5.0 V 22 p R4 J2 10 k R3 C1 10 k 100 m J1 +5.0 V C2 100 n +5.0 V 1 5.0 V REGULATOR OUTPUT GND MC78L05ACP C2 R8 2 270 R INPUT 10 n D1 REWORK 3 5 MMA2200W 3 +5.0 V 4 OUTPUT ON/OFF SWITCH 9.0 V BATTERY 1.0 k SELF-TEST VS GND BYPASS C3 2 6 C1 0.1 m Figure 3. Impact Measurement Schematic Drawing 2-68 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 0.1 m Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1611 START INITIALIZATION CLEAR I/O PORTS DISPLAY "CAL" FOR 4 SECONDS AUTO-ZERO Freescale Semiconductor, Inc... READ ACCELEROMETER CURRENT VALUE > 2.0 g? N ACCUMULATE THE DATA Y IS THE NUMBER OF SAMPLES ACCUMULATED = 128? IS THE IMPACT > 7.0 g? N Y Y ACTIVATE THE BUZZER / LED IS THE CURRENT VALUE > PEAK VALUE? N TAKE THE AVERAGE OF THE DATA Y IS THE 3 SECOND FOR THE PEAK VALUE DISPLAY OVER? N N Y N IS THE PEAK VALUE BEEN DISPLAY > 3 SECOND? OUTPUT THE CURRENT VALUE TO LCD Y PEAK VALUE = CURRENT VALUE SET 3 SECOND FOR THE TIMER INTERRUPT OUTPUT PEAK VALUE TO LCD Motorola Sensor Device Data Figure 4. Main Program Flowchart www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-69 AN1611 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... SOFTWARE SOURCE/ASSEMBLY PROGRAM CODE ****************************************************************************** * * * Accelerometer Demo Car Version 2.0 * * * * The following code is written for MC68HC705B16 using MMDS05 software * * Version 1.01 * * CASM05 - Command line assembler Version 3.04 * * P & E Microcomputer Systems, Inc. * * * * Written by : C.S. Chua * * 29 August 1996 * * * * * * Copyright Motorola Electronics Pte Ltd 1996 * * All rights Reserved * * * * This software is the property of Motorola Electronics Pte Ltd. * * * * Any usage or redistribution of this software without the express * * written consent of Motorola is strictly prohibited. * * * * Motorola reserves the right to make changes without notice to any * * products herein to improve reliability, function, or design. Motorola * * does not assume liability arising out of the application or use of any * * product or circuit described herein, neither does it convey license * * under its patents rights nor the rights of others. Motorola products are * * not designed, intended or authorised for use as component in systems * * intended to support or sustain life or for any other application in * * which the failure of the Motorola product could create a situation * * a situation where personal injury or death may occur. Should the buyer * * shall indemnify and hold Motorola products for any such unintended or * * unauthorised application, buyer shall indemnify and hold Motorola and * * its officers, employees, subsidiaries, affiliates, and distributors * * harmless against all claims, costs, damages, expenses and reasonable * * attorney fees arising out of, directly or indirectly, any claim of * * personal injury or death associated with such unintended or unauthorised * * use, even if such claim alleges that Motorola was negligent regarding * * the design or manufacture of the part. * * * * Motorola and the Motorola logo are registered trademarks of Motorola Inc.* * * * Motorola Inc. is an equal opportunity/affirmative action employer. * * * ****************************************************************************** ****************************************************************************** * * * Software Description * * * * This software is used to read the output of the accelerometer MMA2200W * * and display it to a LCD as gravity force. It ranges from -55g to +55g * * with 0g as zero acceleration or constant velocity. The resolution is * * 0.5g. * * * * The program will read from the accelerometer and hold the maximum * * deceleration value for about 3.0 seconds before resetting. At the same * * time, the buzzer/LED is activated if the impact is more than 7.0g. * * However, if the maximum deceleration changes before 3.0 seconds, it * * will update the display using the new value. Note that positive value * * implies deceleration whereas negative value implies acceleration * * * ****************************************************************************** ****************************************** * * * Initialisation * * * ****************************************** PORTA EQU $00 ; Last digit PORTB EQU $01 ; Second digit (and negative sign) PORTC EQU $02 ; First digit (and decimal point) ADDATA EQU $08 ; ADC Data ADSTAT EQU $09 ; ADC Status PLMA EQU $0A ; Pulse Length Modulator (Output to Buzzer) MISC EQU $0C ; Miscellaneous Register (slow/fast mode) TCONTROL EQU $12 ; Timer control register TSTATUS EQU $13 ; Timer Status Register OCMPHI1 EQU $16 ; Output Compare Register 1 High Byte 2-70 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1611 OCMPLO1 EQU $17 ; Output Compare Register 1 Low Byte TCNTHI EQU $18 ; Timer Count Register High Byte TCNTLO EQU $19 ; Timer Count Register Low Byte OCMPHI2 EQU $1E ; Output Compare Register 2 High Byte OCMPLO2 EQU $1F ; Output Compare Register 2 Low Byte ****************************************** * * * User-defined RAM * * * ****************************************** SIGN EQU $54 ; Acceleration (-) or deceleration (+) PRESHI2 EQU $55 ; MSB of accumulated acceleration PRESHI EQU $56 PRESLO EQU $57 ; LSB of accumulated acceleration PTEMPHI EQU $58 ; Acceleration High Byte (Temp storage) PTEMPLO EQU $59 ; Acceleration Low Byte (Temp storage) ACCHI EQU $5A ; Temp storage of acc value (High byte) ACCLO EQU $5B ; (Low byte) ADCOUNTER EQU $5C ; Sampling Counter AVERAGE_H EQU $5D ; MSB of the accumulated data of low g AVERAGE_M EQU $5E AVERAGE_L EQU $5F ; LSB of the accumulated data of low g SHIFT_CNT EQU $60 ; Counter for shifting the accumulated data AVE_CNT1 EQU $61 ; Number of samples in the accumulated data AVE_CNT2 EQU $75 TEMPTCNTHI EQU $62 ; Temp storage for Timer count register TEMPTCNTLO EQU $63 ; Temp storage for Timer count register DECHI EQU $64 ; Decimal digit high byte DECLO EQU $65 ; Decimal digit low byte DCOFFSETHI EQU $66 ; DC offset of the output (high byte) DCOFFSETLO EQU $67 ; DC offset of the output (low byte) MAXACC EQU $68 ; Maximum acceleration TEMPHI EQU $69 TEMPLO EQU $6A TEMP1 EQU $6B ; Temporary location for ACC during delay TEMP2 EQU $6C ; Temporary location for ACC during ISR DIV_LO EQU $6D ; No of sampling (low byte) DIV_HI EQU $6E ; No of sampling (high byte) NO_SHIFT EQU $6F ; No of right shift to get average value ZERO_ACC EQU $70 ; Zero acceleration in no of ADC steps HOLD_CNT EQU $71 ; Hold time counter HOLD_DONE EQU $72 ; Hold time up flag START_TIME EQU $73 ; Start of count down flag RSHIFT EQU $74 ; No of shifting required for division ORG $300 ; ROM space 0300 to 3DFE (15,104 bytes) DB $FC ; Display "0" DB $30 ; Display "1" DB $DA ; Display "2" DB $7A ; Display "3" DB $36 ; Display "4" DB $6E ; Display "5" DB $EE ; Display "6" DB $38 ; Display "7" DB $FE ; Display "8" DB $7E ; Display "9" HUNDREDHI DB $00 ; High byte of hundreds HUNDREDLO DB $64 ; Low byte of hundreds TENHI DB $00 ; High byte of tens TENLO DB $0A ; Low byte of tens ****************************************** * * * Program starts here upon hard reset * * * ****************************************** RESET CLR PORTC ; Port C = 0 CLR PORTB ; Port B = 0 CLR PORTA ; Port A = 0 LDA #$FF STA $06 ; Port C as output STA $05 ; Port B as output STA $04 ; Port A as output LDA TSTATUS ; Dummy read the timer status register CLR OCMPHI2 ; so as to clear the OCF CLR OCMPHI1 LDA OCMPLO2 JSR COMPRGT CLR START_TIME Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-71 Freescale Semiconductor, Inc. AN1611 Freescale Semiconductor, Inc... IDLE REPEAT SHIFTING 2-72 LDA STA CLI LDA STA LDA STA LDA STA LDA JSR DECA BNE LDA STA LDA STA LDA STA JSR LDX LDA STA MUL STA TXA STA CLR LDA STA LDA STA LDA STA LDA STA JSR CLR CLR CLR CLR CLR CLR CLR JSR LDA ADD CMP BLO LDA ADD STA CLRA ADC STA CLRA ADC STA LDA ADD STA CLRA ADC STA CMP BNE LDA CMP BNE INC LSR ROR ROR LDA CMP BLO LDA #$40 TCONTROL #$CC PORTC #$BE PORTB #$C4 PORTA #16 DLY20 IDLE #$00 DIV_LO #$80 DIV_HI #!15 NO_SHIFT READAD #5 PTEMPLO ZERO_ACC DCOFFSETLO DCOFFSETHI HOLD_CNT #$10 DIV_LO #$00 DIV_HI #$4 NO_SHIFT ZERO_ACC MAXACC ADTOLCD START_TIME AVE_CNT1 AVE_CNT2 SHIFT_CNT AVERAGE_L AVERAGE_M AVERAGE_H READAD ZERO_ACC #$04 PTEMPLO CRASH PTEMPLO AVERAGE_L AVERAGE_L ; Enable the output compare interrupt ; Interrupt begins here ; Port C = 1100 1100 Letter "C" ; Port B = 1011 1110 Letter "A" ; Port A = 1100 0100 Letter "L" ; ; ; ; ; ; ; ; Idling for a while (16*0.125 = 2 sec) for the zero offset to stabilize before perform auto-zero Sample the data 32,768 times and take the average 8000 H = 32,768 Right shift of 15 equivalent to divide by 32,768 Overall sampling time = 1.033 s) ; Zero acceleration calibration ; Calculate the zero offset ; DC offset = PTEMPLO * 5 ; Save the zero offset in the RAM ; ; ; ; ; Sample the data 16 times and take the average 0100 H = 16 Right shift of 4 equivalent to divide by 16 Overall sampling time = 650 us ; Display 0.0g at the start ; Read acceleration from ADC ; ; ; ; ; If the acceleration < 2.0g Accumulate the averaged results for 128 times and take the averaging again to achieve more stable reading at low g AVERAGE_M AVERAGE_M AVERAGE_H AVERAGE_H #$01 AVE_CNT1 AVE_CNT1 AVE_CNT2 AVE_CNT2 #$04 REPEAT AVE_CNT1 #$00 REPEAT SHIFT_CNT AVERAGE_H AVERAGE_M AVERAGE_L SHIFT_CNT #$0A SHIFTING AVERAGE_L ; Take the average of the 128 samples For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1611 STA PTEMPLO LDA HOLD_CNT ; Check if the hold time of crash data CMP #$00 ; is up BNE NON-CRASH LDA PTEMPLO ; If yes, display the current acceleration STA MAXACC ; value JSR ADTOLCD BRA NON-CRASH CRASH LDA ZERO_ACC ADD #$0E ; If the crash is more than 7g CMP PTEMPLO ; 7g = 0E H * 0.5 BHS NO_INFLATE LDA #$FF ; activate the LED STA PLMA NO_INFLATE JSR MAXVALUE ; Display the peak acceleration JSR ADTOLCD NON-CRASH CLR SHIFT_CNT CLR AVE_CNT1 CLR AVE_CNT2 CLR AVERAGE_L CLR AVERAGE_M CLR AVERAGE_H BRA REPEAT ; Repeat the whole process ****************************************** * * * Delay Subroutine * * (162 * 0.7725 ms = 0.125 sec) * * * ****************************************** DLY20 STA TEMP1 LDA #!162 ; 1 unit = 0.7725 ms OUTLP CLRX INNRLP DECX BNE INNRLP DECA BNE OUTLP LDA TEMP1 RTS ****************************************** * * * Reading the ADC data X times * * and take the average * * X is defined by DIV_HI and DIV_LO * * * ****************************************** READAD LDA #$25 STA ADSTAT ; AD status = 25H CLR PRESHI2 CLR PRESHI ; Clear the memory CLR PRESLO CLRX CLR ADCOUNTER LOOP128 TXA CMP #$FF BEQ INC_COUNT BRA CONT INC_COUNT INC ADCOUNTER CONT LDA ADCOUNTER ; If ADCOUNTER = X CMP DIV_HI ; Clear bit = 0 BEQ CHECK_X ; Branch to END100 BRA ENDREAD CHECK_X TXA CMP DIV_LO BEQ END128 ENDREAD BRCLR 7,ADSTAT,ENDREAD ; Halt here till AD read is finished LDA ADDATA ; Read the AD register ADD PRESLO ; PRES = PRES + ADDATA STA PRESLO CLRA ADC PRESHI STA PRESHI CLRA ADC PRESHI2 STA PRESHI2 INCX ; Increase the AD counter by 1 BRA LOOP128 ; Branch to Loop128 END128 CLR RSHIFT ; Reset the right shift counter Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-73 AN1611 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... DIVIDE INC RSHIFT ; Increase the right counter LSR PRESHI2 ROR PRESHI ; Right shift the high byte ROR PRESLO ; Right shift the low byte LDA RSHIFT CMP NO_SHIFT ; If the right shift counter >= NO_SHIFT BHS ENDDIVIDE ; End the shifting JMP DIVIDE ; otherwise continue the shifting ENDDIVIDE LDA PRESLO STA PTEMPLO RTS ****************************************** * * * Timer service interrupt * * Alternates the Port data and * * backplane of LCD * * * ****************************************** TIMERCMP STA TEMP2 ; Push Accumulator COM PORTC ; Port C = - (Port C) COM PORTB ; Port B = - (Port B) COM PORTA ; Port A = - (Port A) LDA START_TIME ; Start to count down the hold time CMP #$FF ; if START_TIME = FF BNE SKIP_TIME JSR CHECK_HOLD SKIP_TIME BSR COMPRGT ; Branch to subroutine compare register LDA TEMP2 ; Pop Accumulator RTI ****************************************** * * * Check whether the hold time * * of crash impact is due * * * ****************************************** CHECK_HOLD DEC HOLD_CNT LDA HOLD_CNT CMP #$00 ; Is the hold time up? BNE NOT_YET LDA #$00 ; If yes, STA PLMA ; stop buzzer LDA #$FF ; Set HOLD_DONE to FF indicate that the STA HOLD_DONE ; hold time is up CLR START_TIME ; Stop the counting down of hold time NOT_YET RTS ****************************************** * * * Subroutine reset * * the timer compare register * * * ****************************************** COMPRGT LDA TCNTHI ; Read Timer count register STA TEMPTCNTHI ; and store it in the RAM LDA TCNTLO STA TEMPTCNTLO ADD #$4C ; Add 1D4C H = 7500 periods STA TEMPTCNTLO ; with the current timer count LDA TEMPTCNTHI ; 1 period = 2 us ADC #$1D STA TEMPTCNTHI ; Save the next count to the register STA OCMPHI1 LDA TSTATUS ; Clear the output compare flag LDA TEMPTCNTLO ; by access the timer status register STA OCMPLO1 ; and then access the output compare RTS ; register ****************************************** * * * Determine which is the next * * acceleration value to be display * * * ****************************************** MAXVALUE LDA PTEMPLO CMP MAXACC ; Compare the current acceleration with BLS OLDMAX ; the memory, branch if it is <= maxacc BRA NEWMAX1 OLDMAX LDA HOLD_DONE ; Decrease the Holdtime when CMP #$FF ; the maximum value remain unchanged 2-74 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1611 BEQ NEWMAX1 ; Branch if the Holdtime is due LDA MAXACC ; otherwise use the current value BRA NEWMAX2 NEWMAX1 LDA #$C8 ; Hold time = 200 * 15 ms = 3 sec STA HOLD_CNT ; Reload the hold time for the next CLR HOLD_DONE ; maximum value LDA #$FF STA START_TIME ; Start to count down the hold time LDA PTEMPLO ; Take the current value as maximum NEWMAX2 STA MAXACC RTS ****************************************** * * * This subroutine is to convert * * the AD data to the LCD * * Save the data to be diaplayed * * in MAXACC * * * ****************************************** ADTOLCD SEI ; Disable the Timer Interrupt !! LDA #$00 ; Load 0000 into the memory STA DECHI LDA #$00 STA DECLO LDA MAXACC LDX #5 MUL ; Acceleration = AD x 5 ADD DECLO ; Acceleration is stored as DECHI STA DECLO ; and DECLO STA ACCLO ; Temporary storage LDA #$00 ; Assume positive deceleration STA SIGN ; "00" positive ; "01" negative CLRA TXA ADC DECHI STA DECHI STA ACCHI ; Temporary storage LDA DECLO SUB DCOFFSETLO ; Deceleration = Dec - DC offset STA DECLO LDA DECHI SBC DCOFFSETHI STA DECHI BCS NEGATIVE ; Branch if the result is negative BRA SEARCH NEGATIVE LDA DCOFFSETLO ; Acceleration = DC offset - Dec SUB ACCLO STA DECLO LDA DCOFFSETHI SBC ACCHI STA DECHI LDA #$01 ; Assign a negative sign STA SIGN SEARCH CLRX ; Start the search for hundred digit LOOP100 LDA DECLO ; Acceleration = Acceleration - 100 SUB HUNDREDLO STA DECLO LDA DECHI SBC HUNDREDHI STA DECHI INCX ; X = X + 1 BCC LOOP100 ; if acceleration >= 100, continue the DECX ; loop100, otherwise X = X - 1 LDA DECLO ; Acceleration = Acceleration + 100 ADD HUNDREDLO STA DECLO LDA DECHI ADC HUNDREDHI STA DECHI TXA ; Check if the MSD is zero AND #$FF BEQ NOZERO ; If MSD is zero, branch to NOZERO LDA $0300,X ; Output the first second digit STA PORTC BRA STARTTEN NOZERO LDA #$00 ; Display blank if MSD is zero STA PORTC Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-75 AN1611 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... STARTTEN LOOP10 CLRX ; Start to search for ten digit LDA DECLO ; acceleration = acceleration - 10 SUB TENLO STA DECLO LDA DECHI SBC TENHI STA DECHI INCX BCC LOOP10 ; if acceleration >= 10 continue the DECX ; loop, otherwise end LDA DECLO ; acceleration = acceleration + 10 ADD TENLO STA DECLO LDA DECHI ADC TENHI STA DECHI LDA $0300,X ; Output the last second digit EOR SIGN ; Display the sign STA PORTB CLRX ; Start to search for the last digit LDA DECLO ; declo = declo - 1 TAX LDA $0300,X ; Output the last digit EOR #$01 ; Add a decimal point in the display STA PORTA CLI ; Enable Interrupt again ! RTS ****************************************** * * * This subroutine provides services * * for those unintended interrupts * * * ****************************************** SWI RTI ; Software interrupt return IRQ RTI ; Hardware interrupt TIMERCAP RTI ; Timer input capture TIMERROV RTI ; Timer overflow SCI RTI ; Serial communication Interface ; Interrupt ORG $3FF2 ; For 68HC05B16, the vector location FDB SCI ; starts at 3FF2 FDB TIMERROV ; For 68HC05B5, the address starts FDB TIMERCMP ; 1FF2 FDB TIMERCAP FDB IRQ FDB SWI FDB RESET 2-76 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1612 Shock and Mute Pager Applications Using Accelerometer INTRODUCTION 30 In the current design, whenever there is an incoming page, the buzzer will "beep" until any of the buttons is depressed. It can be quite annoying or embarrassing sometime when the button is not within your reach. This application note describes the concept of muting the "beeping" sound by tapping the pager lightly, which could be located in your pocket or handbag. This demo board uses an accelerometer, microcontroller hardware/software and a piezo audio transducer. Due to the wide frequency response of the accelerometer from d.c. to 400Hz, the device is able to measure both the static acceleration from the Earth's gravity and the shock or vibration from an impact. This design uses a 40G accelerometer (Motorola P/N: MMA1201P) which yields a minimum acceleration range of -40G to +40G. 20 ACCELEROMETER OUTPUT (G) Freescale Semiconductor, Inc... Prepared by: C.S. Chua Sensor Application Engineering Singapore, A/P 10 0 - 10 - 20 - 30 TAPPING OF ACCELEROMETER - 40 - 50 - 60 - 70 - 0.05 - 0.03 - 0.01 0 0.01 0.03 0.05 TIME (seconds) CONCEPT OF TAP DETECTION To measure the tapping of a pager, the accelerometer must be able to respond in the range of hundreds of hertz. During the tapping of a pager at the top surface, which is illustrated in Figure 1, the accelerometer will detect a negative shock level between -15g to -50g of force depending on the intensity. Similarly, if the tapping action comes from the bottom of the accelerometer, the output will be a positive value. Normally, the peak impact pulse is in the order of a few milliseconds. Figure 2 shows a typical waveform of the accelerometer under shock. TAPPING ACTION FRONT VIEW PCB Figure 1. Tapping Action of Accelerometer Figure 2. Typical Waveform of Accelerometer Under Tapping Action Therefore, we could set a threshold level, either by hardware circuitry or software algorithm, to determine the tapping action and mute the "beeping". In this design, a hardware solution is used because there will be minimal code added to the existing pager software. However, if a software solution is used, the user will be able to program the desire shock level. HARDWARE DESCRIPTION AND OPERATION Since MMA1201P is fully signal-conditioned by its internal op-amp and temperature compensation, the output of the accelerometer can be directly interfaced with a comparator. To simplify the hardware, only one direction (tapping on top of the sensor) is monitored. The comparator is configured in such a way that when the output voltage of the accelerometer is less than the threshold voltage or Vref (refer to Figure 3), the output of the comparator will give a logic "1" which is illustrated in Figure 4. To decrease the Vref voltage or increase the threshold impact in magnitude, turn the trimmer R2 anti-clockwise. REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-77 Freescale Semiconductor, Inc. AN1612 For instance, if the threshold level is to be set to -20g, this will correspond to a Vref voltage of 1.7 V. +5.0 V VREF 8 3 VIN 2 VREF R1 VOUT 7 6 1 5 100 k 2 + 100 k R2 C3 1.0 m OFFSET THRESHOLD Under normal condition, Vin (which is the output of the accelerometer) is at about 2.5V. Since Vin is higher than Vref, the output of the comparator is at logic "0". During any shock or impact which is greater than -20g in magnitude, the output voltage of the accelerometer will go below Vref. In this case, the output logic of the comparator changes from "0" to "1". When the pager is in silence mode, the vibrator produces an output of about 2g. This will not trigger the comparator. Therefore, even in silence mode, the user can also tap the pager to stop the alert. Refer to Figure 5 for the vibrator waveform. 1 Figure 3. Comparator Circuitry 6.0 2.0 1.5 VIBRATOR MOVEMENT (G) 5.0 4.0 V OUT (V) Freescale Semiconductor, Inc... U1 + 4 +5.0 V LM311N - + V ) DDGV G + 2.5 ) (0.04 [* 20]) + 1.7 V 3.0 2.0 1.0 0.5 0 - 0.5 -1.0 1.0 -1.5 0 - 0.05 - 0.03 - 0.01 0 0.01 0.03 0.05 - 2.0 - 0.025 - 0.015 - 0.005 TIME (seconds) 0.005 0.015 0.025 TIME (seconds) Figure 4. Comparator Output Waveform 2-78 0 Figure 5. Vibrator Waveform For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Figure 6 is a schematic drawing of the whole demo and Figures 7, 8, and 9 show the printed circuit board and compo- AN1612 nent layout for the shock and mute pager. Table 1 is the corresponding part list. R4 MC78L05ACP 3 J2 INPUT 1 2 C10 OUTPUT GND 2 0.33 m +5.0 V 1 10 M +5.0 V C9 X1 C3 0.1 m 16 10 k 18 19 +5.0 V S1 C5 41 0.1 m U1 8 C7 VS OUTPUT 6 C1 0.1 m 8 R8 5 3 1.0 k BYPASS SELF-TEST MMA1201P 2 C8 4 0.1 m 10 n R3 10 k LM311N - U2 + 4 6 1 5 7 +5.0 V GND 7 R7 +5.0 V R1 10 k J1 100 k R6 2 R2 1 180 R 100 k + C12 OSC1 /RESET /IRQ 22 TCAP1 23 TCAP2 10 n +5.0 V C2 C4 22 p U5 R5 Freescale Semiconductor, Inc... 4 MHz 22 p 1.0 m D1 VSS 8 VRH 7 VRL 31 PA0 30 PA1 29 PA2 28 PA3 27 PA4 26 PA5 25 PA6 24 PA7 39 38 37 36 35 34 33 32 PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 +5.0 V R9 10 k OSC2 VDD 17 +5.0 V 10 2 TCMP1 1 TCMP2 C6 10 n C11 + 47 m 52 TDO 51 SCLK 20 PLMA 21 PLMB PC0 PC1 PC2/ECLK PC3 PC4 PC5 PC6 PC7 PD0/AN0 PD1/AN1 PD2/AN2 PD3/AN3 PD4/AN4 PD5/AN5 PD6/AN6 PD7/AN7 49 48 47 46 45 44 43 42 U4 PIEZO TRANSDUCER 14 13 12 11 9 5 4 3 MC68HC705B16CFN U3 S2 Figure 6. Overall Schematic Diagram of the Demo Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-79 Freescale Semiconductor, Inc. AN1612 SHOCK & MUTE PAGER 9V D1 U4 GND J2 C9 U5 R6 R3 R1 C10 U2 U1 C7 C8 C2 C1 C12 C6 R2 R4 C3 X1 S1 C11 R8 S2 C4 R5 R7 J1 U3 Freescale Semiconductor, Inc... R9 C5 Figure 7. Silk Screen of the PCB Figure 8. Solder Side of the PCB Table 1. Bill of Material for the Shock and Mute Pager Device Type Qty. Value References Ceramic Capacitor 4 0.1 C1, C2, C7, C9 Ceramic Capacitor 2 22p C3, C4 Ceramic Capacitor 3 10n C5, C6, C8 Solid Tantalum 1 0.33 C10 Electrolytic Capacitor 1 47 C11 Electrolytic Capacitor 1 1 C12 LED 1 5mm D1 Header 1 2 way J1 PCB Terminal Block 1 2 way J2 Resistor 1 100k R1 Single Turn Trimmer 1 100k R2 Resistor 4 10k R3, R5, R7, R9 1 10M R4 1 180R R6 1 1k R8 Push Button 2 6mm S1, S2 MMA1201P 1 -- U1 LM311N 1 -- U2 MC68HC705B16CFN 1 -- U3 Piezo Transducer 1 -- U4 MC78L05ACP 1 -- U5 Crystal 1 4MHz X1 "5% 0.25W "5% 0.25W Resistor "5% 0.25W Resistor "5% 0.25W Resistor "5% 0.25W 2-80 Figure 9. Component Side of the PCB SOFTWARE DESCRIPTION Upon powering up the system, the piezo audio transducer is activated simulating an incoming page, if the pager is in sound mode (jumper J1 in ON). Then, the accelerometer is powered up and the output of the comparator is sampled to obtain the logic level. The "beeping" will continue until the accelerometer senses an impact greater than the threshold level. Only then the alert is muted. However when the pager is in silence mode (jumper J1 is OFF), which is indicated by the blinking red LED, the accelerometer is not activated. To stop the alert, press the push-button S2. To repeat the whole process, simply push the reset switch S1. Figure 10 is a flowchart for the program that controls the system. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1612 RECEIVE A PAGE Y IS IT IN SILENCE MODE? N TURN ON THE SHOCK SENSOR Freescale Semiconductor, Inc... N IS BUTTON ACTIVATED? Y IS SHOCK SENSOR ACTIVATED OR BUTTON ACTIVATED? N Y TURN OFF THE SHOCK SENSOR TURN OFF THE BUZZER OR VIBRATOR END Figure 10. Main Program Flowchart CONCLUSION The shock and mute pager design uses a comparator to create a logic level output by comparing the accelerometer output voltage and a user-defined reference voltage. The Motorola Sensor Device Data flexibility of this minimal component, high performance design makes it compatible with many different applications, e.g. hard disk drive knock sensing, etc. The design presented here uses a comparator which yields excellent logic-level outputs and output transition speeds for many applications. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-81 AN1612 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... SOFTWARE SOURCE/ASSEMBLY PROGRAM CODE ****************************************************************************** * * * Pager Shock & Mute Detection Version 1.0 * * * * The following code is written for MC68HC705B16 using MMDS05 software * * Version 1.01 * * CASM05 - Command line assembler Version 3.04 * * P & E Microcomputer Systems, Inc. * * * * Written by : C.S. Chua * * 9th January 1997 * * * * Software Description * * * * J1 ON - Sound mode * * Buzzer will turn off if the accelerometer is tapped or switch S2 is * * depressed. * * * * J1 OFF - Silence mode * * LED will turn off if and only if S2 is depressed * * * ****************************************************************************** ****************************************** * * * I/O Declaration * * * ****************************************** PORTB EQU $01 ; Port B PLMA EQU $0A ; D/A to control buzzer TCONTROL EQU $12 ; Timer control register TSTATUS EQU $13 ; Timer Status Register OCMPHI1 EQU $16 ; Output Compare Register 1 High Byte OCMPLO1 EQU $17 ; Output Compare Register 1 Low Byte TCNTHI EQU $18 ; Timer Count Register High Byte TCNTLO EQU $19 ; Timer Count Register Low Byte OCMPHI2 EQU $1E ; Output Compare Register 2 High Byte OCMPLO2 EQU $1F ; Output Compare Register 2 Low Byte ****************************************** * * * RAM Area ($0050 - $0100) * * * ****************************************** ORG $50 STACK RMB 4 ; Stack segment TEMPTCNTLO RMB 1 ; Temp. storage of timer result (LSB) TEMPTCNTHI RMB 1 ; Temp. storage of timer result (MSB) ****************************************** * * * ROM Area ($0300 - $3DFD) * * * ****************************************** ORG $300 ****************************************** * * * Program starts here upon hard reset * * * ****************************************** RESET CLR PORTB ; Initialise Ports LDA #%01001000 ; Configure Port B STA $05 LDA TSTATUS ; Dummy read the timer status register so as to clear the OCF CLR OCMPHI2 CLR OCMPHI1 LDA OCMPLO2 JSR COMPRGT LDA #$40 ; Enable the output compare interrupt STA TCONTROL LDA #10 ; Idle for a while before "beeping" IDLE JSR DLY20 DECA BNE IDLE CLI ; Interrupt begins here BRSET 1,PORTB,SILENCE ; Branch if J1 is off BSET 6,PORTB ; Turn on accelerometer JSR DLY20 ; Wait till the supply is stable TEST BRSET 5,PORTB,MUTE ; Sample shock sensor for tapping BRCLR 7,PORTB,MUTE ; Sample switch S2 for muting JMP TEST MUTE BCLR 6,PORTB ; Turn off accelerometer SEI CLR PLMA ; Turn off buzzer 2-82 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1612 Freescale Semiconductor, Inc... DONE SILENCE JMP DONE ; End BRSET 7,PORTB,SILENCE ; Sample switch S2 for stopping LED SEI BCLR 3,PORTB ; Turn off LED JMP DONE ; End ****************************************** * * * Timer service interrupt * * Alternates the PLMA data * * and bit 3 of Port B * * * ****************************************** TIMERCMP BSR COMPRGT ; Branch to subroutine compare register BRSET 1,PORTB,SKIPBUZZER ; Branch if J1 is OFF LDA PLMA EOR #$80 ; Alternate the buzzer STA PLMA RTI SKIPBUZZER BRSET 3,PORTB,OFF_LED ; Alternate LED supply BSET 3,PORTB RTI OFF_LED BCLR 3,PORTB RTI ****************************************** * * * Subroutine reset * * the timer compare register * * * ****************************************** COMPRGT LDA TCNTHI ; Read Timer count register STA TEMPTCNTHI ; and store it in the RAM LDA TCNTLO STA TEMPTCNTLO ADD #$50 ; Add C350 H = 50,000 periods STA TEMPTCNTLO ; with the current timer count LDA TEMPTCNTHI ; 1 period = 2 us ADC #$C3 STA TEMPTCNTHI ; Save the next count to the register STA OCMPHI1 LDA TSTATUS ; Clear the output compare flag LDA TEMPTCNTLO ; by access the timer status register STA OCMPLO1 ; and then access the output compare register RTS ****************************************** * * * Delay Subroutine for 0.20 sec * * * * Input: None * * Output: None * * * ****************************************** DLY20 STA STACK+2 STX STACK+3 LDA #!40 ; 1 unit = 0.7725 mS OUTLP CLRX INNRLP DECX BNE INNRLP DECA BNE OUTLP LDX STACK+3 LDA STACK+2 RTS ****************************************** * * * This subroutine provides services * * for those unintended interrupts * * * ****************************************** SWI RTI ; Software interrupt return IRQ RTI ; Hardware interrupt TIMERCAP RTI ; Timer input capture TIMERROV RTI ; Timer overflow interrupt SCI RTI ; Serial communication Interface Interrupt ORG $3FF2 ; For 68HC05B16, the vector location FDB SCI ; starts at 3FF2 FDB TIMERROV ; For 68HC05B5, the address starts at 1FF2 FDB TIMERCMP FDB TIMERCAP FDB IRQ FDB SWI FDB RESET Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-83 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1632 MMA1201P Product Overview and Interface Considerations Freescale Semiconductor, Inc... Prepared by: Carlos Miranda Systems and Applications Engineer and Gary O'Brien New Product Development Engineer INTRODUCTION Silicon micromachined accelerometers designed for a variety of applications including automotive airbag deployment systems must meet stringent performance requirements and still remain low cost. Achieving the requisite enhanced functionality encompasses overcoming challenges in both transducer micromachining and subsequent signal conditioning. Motorola's accelerometer architecture includes two separate elements in a single package to achieve overall functionality: a sensing element ("g-cell") and a signal conditioning element ("control ASIC"). Figure 1 shows a functional block diagram of Motorola's new MMA1201P. The transducer is a surface micromachined differential capacitor with two fixed plates and a third movable plate. The movable plate is attached to an inertial mass. When acceleration is applied to the device, the inertial mass is displaced causing a change in capacitance. The second die is a CMOS control ASIC which acts as a capacitance to voltage converter and conditions the signal to provide a high level output. The output signal has an offset voltage nominally equivalent to VDD/2 so that both positive and negative acceleration can be measured. G-Cell This document describes Motorola's new MMA1201P accelerometer, which uses a new control ASIC architecture. It explains important new features that have been incorporated into the ASIC, and presents an overview of the key performance characteristics of the new accelerometer. The document also details the minimum supporting circuitry needed to operate a Motorola accelerometer and interface it to an MCU. Finally, the power supply rejection ratio (PSRR) characteristics and an aliasing gain model are presented. MMA1201P FEATURES Several design enhancements have been implemented into the new MMA1201P. The oscillator circuit, which is the heart of the ASIC, has been redesigned to improve stability over temperature. A filter has been added to the power supply line for internally generated biases. A new sensing scheme is used to sample the differential capacitor transducer and condition the signal. Finally, the temperature compensation stage has been redesigned to be trimmable. A block diagram representation of the new accelerometer, in a 16 pin DIP package, is shown in Figure 1. For simplicity, the EPROM trim and the self-test circuit blocks have been omitted. CMOS Control ASIC Capacitance to Voltage Converter VDD Filter ST Trimmable Gain Stage Trimmable Switched Capacitor Filter Trimmable Temp. Comp. Output Stage Oscillator VOUT VSS VDD Figure 1. Block Diagram Representing the MMA1201P REV 2 2-84 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... * Oscillator The oscillator has been redesigned to center the nominal frequency within the trimming range and to have better temperature compensation. As shown in Figure 1, the oscillator controls three switched capacitor circuit sub- blocks within the ASIC, thus having direct impact on their performance. The trimmable oscillator enhances the control of other performance parameters and enables the part to meet tighter specification tolerances. Additionally, the placement of the oscillator on the silicon die has changed, contributing to a 50% reduction in the noise of the part. * Power Supply Filter An internal capacitor has been added between the VDD and VSS pins to provide some de-coupling of the power supply. Also, a lowpass filter has been added to the circuitry that supplies power to the transducer element and that sets the DC level of the capacitance-to-voltage converter stage. The filter response suppresses high frequency noise, but maintains a ratiometric output. * New Sensing Scheme The capacitance-to-voltage converter employs innovative circuit techniques (at the time of this writing, patents are pending) to improve signal ratiometricity. Amplification is achieved using an EPROM trimmable gain stage, providing capability for both coarse and fine tuning. As in the previous version of the control ASIC, the second gain stage is cascaded by a switched capacitor four pole Bessel lowpass filter, with a unity gain response and -3 dB frequency at 400 Hz. * Temperature Compensation The final stage in the ASIC performs temperature compensation of gain. Thus, the temperature coefficient for sensitivity is set using EPROM trim. PERFORMANCE ENHANCEMENTS Motorola's new MMA1201P accelerometer provides performance enhancements in a number of areas, including ratiometric output, signal-to-noise ratio, output filter response, and temperature compensation. For complete details, refer to the MMA1201P data sheet. * Ratiometric Output The offset voltage and the sensitivity of the part are ratiometric with supply voltage. Typical error values are less than 0.5%. * Signal to Noise Ratio The noise has been reduced by 50% and is specified at 3.5 mV RMS maximum. Typical values are about 2.0 mV RMS . As a result, the signal to noise ratio of the part is about 50 dB. * Lowpass Filter Response The frequency response of the four pole Bessel lowpass filter has the -3 dB frequency at 400 Hz. The tolerance has been narrowed by 60% and is specified at 40 Hz. " * Temperature Compensation The sensitivity is very uniform over temperature, with typical errors of about 1% over the specified temperature range. Also, although the spec allows for the equivalent of " Motorola Sensor Device Data AN1632 5 mV/C for the temperature coefficient of offset, typical values are actually less than 2 mV/C, at VDD equal to 5 V. INTERFACE CONSIDERATIONS With only four active pin connections, Motorola's accelerometers are very easy to use. There are only a few simple considerations to be taken into account to ensure reliable operation and attain the high level of performance that the can part offer. * Power Supply Power is applied to the accelerometer through the VDD pin. For optimum performance, it is recommended that the part be powered with a voltage regulator such as the Motorola MC78L05. An optional 0.1 F capacitor can be placed on the VDD pin to complement the accelerometer's internal capacitor and provide additional de-coupling of the supply. The capacitor should be physically located as close as possible to the accelerometer. * Ground Ground is applied through the VSS pin. Whenever possible it is recommended that a solid ground plane be used so that the impedance of the ground path is minimized. If this is not possible, it is strongly recommended that a low impedance trace (no additional components should be connected to it) be used to directly connect the VSS pin to the power supply ground. * Self-test The ST pin is an active, high logic level input pin that provides a way for the user to verify proper operation of the part. It is pulled down internally. Therefore, for normal operation, the user could apply a logic level "0" or leave it unconnected. Applying a logic level "1" to the ST pin will apply the equivalent of a 25 g acceleration to the transducer, and the user should see a change in the output equivalent to 25 times the part's rated sensitivity. * Output The accelerometer's output is measured at the VOUT pin. As shown in Figure 1, the ASIC's oscillator controls the switched capacitor lowpass filter, with a nominal operating frequency of 65 kHz. As a result, a clock noise component of about 2 mVpeak may be present at 65 kHz. Therefore, it is recommended that the user place a simple RC lowpass filter on the VOUT pin to reduce the clock noise present in the output signal. Recommended values are a 1 k resistor and a 0.01 F capacitor. These values produce a filter with a -3 dB frequency at about 16 kHz, which will not interfere with the response of the internal Bessel filter, yet will provide sufficient attenuation (approximately -12 dB) of the clock noise. Placing a filter on the output is especially recommended for applications where the signal will be fed into a stand-alone A/D converter, and in cases where the signal will be amplified to a level where the amplified clock noise may begin to contribute significantly to the noise floor of the system. However, if using an MCU or microprocessor in the system, the user may choose to use a software algorithm to digitally filter the signal, instead of using the analog RC filter. This option would have to be evaluated based on the system performance requirements. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-85 Freescale Semiconductor, Inc. AN1632 * Connection to the A/D on an MCU When using the accelerometer with the analog to digital converter on an MCU, it is important to connect the supply and ground pins of the accelerometer and the VRH and VRL pins of the MCU to the same supply and ground traces, respectively. This will maximize the ratiometricity of the system by avoiding voltage differences that may result from trace impedances. Figure 2 shows the recommended supporting circuitry for operating the new accelerometer. Part (a) shows the16 pin DIP package version, the MMA1201P, while part (b) shows the 6 pin Wingback package version, the MMA2200W. For the MMA1201P, pins 1, 2, 3, 6, 14, 15, and 16 have no internal connections, and pins 9 through 13 are used for calibration and trimming in the factory. These pins should all be left unconnected. For the MMA2200W, pins 1 and 4, and the wings (supporting pins) should be left unconnected. MMA1201P VCC LOGIC INPUT 4 ST R1 8 VDD C1 5 11 TRIM 3 0.1 m F Freescale Semiconductor, Inc... VOUT 1k W OUTPUT SIGNAL C2 m 0.01 F 7 VSS (a) MMA2200W VCC LOGIC INPUT 2 ST R1 6 VDD C1 m 0.1 F VOUT 3 1k W OUTPUT SIGNAL C2 m 0.01 F 5 VSS (b) Figure 2. Accelerometers with Recommended Supporting Circuitry PSRR AND ALIASING GAIN MODEL Although the operational amplifiers in the MMA1201P's control ASIC have a high power supply rejection ratio with a fairly wide bandwidth, because the accelerometer is in reality a sampled analog system using switched capacitor technology, it is possible that when powered with a switching power supply, noise from the supply will appear in the output signal. This is known as aliasing, the result being a signal with frequency equal to the difference between the frequency of the power supply noise and the accelerometer's sampling frequency. Aliasing gain is defined as the power of the output signal relative to an injected sinusoid on the VDD line powering the accelerometer. Typical switching power supplies have operating frequencies between 50 and 100 kHz. The operating frequency of the accelerometer's switching capacitor circuitry is roughly 65 kHz. Should the fundamental frequency of the switching power supply, or its harmonics, fall within 400 Hz of the ASIC's fundamental frequency (or its harmonics), then any noise present in the power supply will be aliased into the passband of the accelerometer. As will be explained later in this section, there are several simple ways to avoid aliasing. 2-86 As shown in Figure 1, there are many different signal processing stages in the ASIC. As a result, the aliasing gain characteristics of the part are a little bit more complex than explained in the previous paragraph. An analysis was done to characterize the worst case aliasing gain of the accelerometer. Devices from three production lots were used. The parts were tested at 105_C with 5.25 V on VDD. The gain code was set to the nominal value plus 4. Thus, the parts had a sensitivity that was approximately twice that of standard parts. Figure 3, shows a plot of the aliasing gain model that was developed. The model is based on the worst case results; typical parts should perform much better having much lower aliasing gain. The following equation was used to fit the data and generate the model: Aliasing Gain = 1.6965 + 0.0029 * Freq. (kHz) + HRC1 * Freq. (kHz) + HRC2 where HRC1 and HRC2 are coefficients used in the model. Their values vary for each harmonic. Figure 4 lists the values of HRC1 and HRC2 for the fundamental frequency and the first 5 harmonics. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1632 3.5 3 ALIASING GAIN (V/V) 2.5 2 1.5 Freescale Semiconductor, Inc... 1 0.5 0 0 Fundamental 1st 2nd 3rd 4th 5th SAMPLING FREQUENCY AND HARMONICS Figure 3. Worst Case Aliasing Gain Model Derived from Characterization Data Harmonic Freq. (kHz) Fundamental 65 HRC1 HRC2 *2.1120 *1.4881 *4.1572 *0.2919 0.0101 1st 130 *0.0016 2nd 195 0.0237 3rd 260 4th 325 5th 390 *0.0060 *0.0098 *0.0164 Aliasing Gain 0.4242 0.3674 2.7116 0.6007 3.7439 3.2017 4.3054 0.7361 Figure 4. Values for Worst Case Aliasing Gain Model The aliasing gain model can be used to estimate the amount of noise that can be expected on the output due to noise in the switching power supply. As an example, consider a switching power supply operating at 65.05 kHz, with peak-to-peak noise levels of 10, 6, 3.3, 2.5, 2, and 1.4 mV for the fundamental and the first five harmonics, respectively. Assume the worst case scenario, an almost perfect match of power supply fundamental frequency with the fundamental of the ASIC and all noise signals in phase. The power supply noise that would be seen at the output due to each harmonic would be calculated as follows: Harmonic Aliasing Gain P.S. Noise Output Noise Fundamental 0.4242 10.00 mV 4.24 mV 1st 0.3674 6.00 mV 2.20 mV 2nd 2.7116 3.33 mV 9.04 mV 3rd 0.6007 2.50 mV 1.50 mV 4th 3.2017 2.00 mV 6.40 mV 5th 0.7361 1.40 mV 1.03 mV Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-87 AN1632 Freescale Semiconductor, Inc. The total output noise would be the sum of the individual components: Total Output Noise = (4.24 + 2.20 + 9.04 + 1.50 + 6.40 + 1.03) mV Total Output Noise = 24.41 mV peak-to-peak. If this output signal were fed into an 8 bit A/D converter, referenced to 5 V full scale, the worst case error due to power supply noise would be equivalent to 1 bit count. The error that can occur in the output due to aliasing gain can be avoided very easily. The easiest method is to power the part with a voltage regulator. Since the voltage regulator provides a clean, steady supply, the possibility of aliasing is eliminated. If the accelerometer is powered with a switching supply, a filter should be placed on the power supply output to eliminate the noise of the harmonics. If placing a filter on the switching supply is not feasible, the user must ensure that the operating frequency of the switching power supply is outside the frequency ranges of the peaks shown in Figure 3. The plot shown is a superposition of the response of the internal four pole Bessel lowpass filter, scaled by the corresponding aliasing gain for each harmonic. The Bessel filter has the -3 dB frequency at 400 Hz and, being of fourth order, has a very steep roll-off outside the passband, with approximately Freescale Semiconductor, Inc... " 2-88 -80 dB of attenuation at 4 kHz. If a switching power supply must be used, its operating frequency should be at least 800 Hz from the accelerometer's sampling frequency. Any switching noise present will be aliased to 800 Hz or higher, where the attenuation will be approximately -24 dB or lower, thus reducing the power supply induced noise below the part's noise floor. CONCLUSION The MMA1201P accelerometer demonstrates Motorola's commitment to continuous product improvement. A new oscillator lowers the noise in the part and enables tighter control of the -3 dB bandwidth of the internal lowpass filter. The supply voltage is routed to the transducer and the DC level reference of the capacitance-to-voltage converter stage through a newly added filter, thus reducing the part's susceptibility to power supply noise. The capacitance-to-voltage converter stage uses new signal conditioning methods, which virtually eliminate ratiometric errors. The temperature compensation for sensitivity is improved, producing a very flat response over temperature. Overall the part offers much enhanced performance and is simpler to use. Equally important, Motorola's MMA1201P accelerometer has remained very price competitive, making it ideal for most applications requiring acceleration sensors. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Baseball Pitch Speedometer AN1635 Prepared by: Carlos Miranda, Systems and Applications Engineer and David Heeley, Systems and Applications Mechanical Engineer Freescale Semiconductor, Inc... INTRODUCTION The Baseball Pitch Speedometer, in its simplest form, consists of a target with acceleration sensors mounted on it, an MCU to process the sensors' outputs and calculate the ball speed, and a display to show the result. The actual implementation, shown in Figure 1, resembles a miniature pitching cage, that can be used for training and/or entertainment. The cage is approximately 6 ft. tall by 3 ft. wide by 6 ft. deep. The upper portion is wrapped in a nylon net to retain the baseballs as they rebound off the target. A natural rubber mat, backed by a shock resistant acrylic plate, serve as the target. Accelerometers, used to sense the ball impact, and buffers, used to drive the signal down the transmission line, are mounted on the back side of the target. The remainder of the electronics is contained in a display box on the top front side of the cage. Accelerometers are sensors that measure the acceleration exerted on an object. They convert a physical quantity into an electrical output signal. Because acceleration is a vector quantity, defined by both magnitude and direction, an accelerometer's output signal typically has an offset voltage and can swing positive and negative relative to the offset, to account for both positive and negative acceleration. An example acceleration profile is shown in Figure 2. Because acceleration is defined as the rate of change of velocity with respect to time, the integration of acceleration as a function of time will yield a net change in velocity. By digitizing and numerically integrating the output signal of an accelerometer through the use of a microcontroller, the "area under the curve" could be computed. The result corresponds to the net change in velocity of the object under observation. This is the basic principle behind the Baseball Pitch Speedometer. Figure 1. David Heeley, mechanical designer of the Baseball Pitch Speedometer Demo, tests his skills at Sensors Expo Boston '97. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-89 Freescale Semiconductor, Inc. AN1635 CAPTURE WINDOW POINT OF IMPACT THRESHOLD LEVEL Freescale Semiconductor, Inc... A B OSCILLATIONS THAT RESULT AS ENERGY IS DISSIPATED SYSTEM AT STEADY RATE Figure 2. Typical Crash Pattern for the Baseball Pitch Speedometer Demo THEORY OF OPERATION When a ball is thrown against the target, the accelerometer senses the impact and produces an analog output signal, proportional to the acceleration measured, resulting in a crash signature. The amplitude and duration of the crash signature is a function of the velocity of the ball. How can this crash signature be correlated to the velocity of the baseball? By making use of the principle of conservation of momentum (see Equation 1). The principle of conservation of momentum states that the total momentum within a closed system remains constant. In our case, the system consists of the thrown ball and the target. mball *Vball,initial + mtarget *Vtarget,initial = mball *Vball,final + mtarget *Vtarget,final Eq. 1 When the ball is thrown, it has a momentum equivalent to mball *Vball,initial. The target initially has zero momentum since it is stationary. When the ball collides with the target, part of the momentum of the ball is transferred to the target, and the target will momentarily experience acceleration, velocity, and some finite, though small, displacement before dissipating the momentum and returning to a rest state. The 2-90 other portion of momentum is retained by the ball as it bounces off the target, due to the elastic nature of the collision. By measuring the acceleration imparted on the target, its velocity is computed through integration. Ideally, if the mass of the ball, the mass of the target, and the final velocity of the ball are known, then the problem could be solved analytically and the initial velocity of the baseball determined. The analysis of the crash phenomenon is, however, actually quite complex. Some factors that must be taken into account and that complicate the analysis greatly, are the spring constant and damping coefficient of the target. The target will be displaced during impact because it is anchored to the frame by a thick rubber mat. This action effectively causes the system to have a certain amount of spring. Also, though the mat is very dense, it will deform somewhat during impact and will act as shock absorber. In addition, the ball itself also has a spring constant and damping coefficient associated with it, since it bounces off the target and, though not noticeable by the naked eye, will deform during the impact. Finally, and of even greater significance, the mass of the ball, the mass of the target, and the final velocity of the ball are neither known nor measured. So how can the system work? For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1635 repeatable. It also eliminated potential error caused by the variability of location of impact on the target that would inevitably result from several manual throws. Figure 3 shows a linear regression plot of the response of the system as a function of incident velocity. As is indicated by the plot, just a simple constant of proportionality could be used to correlate the measured acceleration response to the incident velocity of the ball, with fairly accurate results. The Baseball Pitch Speedometer works by exploiting the fact that the final velocity of the target will be, according to Eq. 1, linearly proportional to the initial velocity of the thrown ball. Therefore, by measuring the acceleration response of the system to various ball velocities, which can be measured by independent means such as a radar gun, the system could be calibrated and a linear model developed. To facilitate the characterization and calibration of the system, a pitching machine was used to ensure that the incident ball speed would be 14000 GRAND TOTAL AS RECORDED BY MCU Freescale Semiconductor, Inc... 12000 10000 8000 Y PREDICTED Y 6000 4000 2000 0 0 10 20 30 40 50 60 BASEBALL SPEED AS RECORDED BY RADAR GUN (mph) Figure 3. Baseball Pitch Speedometer Characterization Data IMPLEMENTATION -- HARDWARE The target mat of the Baseball Pitch Speedometer has an area of approximately 9 ft2 (3 by 3). Even though the rubber material used to construct the target is quite dense and heavy, the transmission of an impact is very poor if the ball strikes the target too far from the sensor. Therefore, to cover Motorola Sensor Device Data such a relatively large area it is necessary to use at least four devices; one centered in each quadrant of the square target. In addition, a shock resistant plate about a quarter inch thick is mounted behind the rubber mat. These features help make the response of the system more uniform and reduce errors that result from the variability of where the ball strikes the target. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-91 Freescale Semiconductor, Inc... AN1635 Freescale Semiconductor, Inc. The bulk of the circuit hardware is contained in a display box mounted on the top front side of the cage. Since the accelerometers are physically located far away from the mother board (about 10 feet of wiring), op-amps were used to buffer the accelerometers' output and drive the transmission line. The four accelerometer signals are then simultaneously fed into a comparator network and four of the ADC inputs on an MC68HC11 microcontroller. The MC68HC11 was selected because it has the capability of converting four A/D channels in one conversion sequence and operates at a higher clock speed. These two features reduce the overall time interval between digitizations of the analog signal (that result from the minimum required time for proper A/D conversion and from software latency) thus allowing a more accurate representation of the acceleration waveform to be captured. The comparator network serves a similar purpose by eliminating the additional software algorithm and execution time that would be required to continually monitor the outputs of all four accelerometers and determine whether impact has occurred or not. By minimizing this delay (some is still present since the output signal must exceed a threshold, and a finite amount of time is required for this) more of the initial and more significant part of the signal is captured. The comparator network employs four LM311's configured to provide an OR function, and a single output is fed into an input capture pin on the MCU. A potentiometer and filter capacitor are used to provide a stable reference threshold voltage to the comparator network. The threshold voltage is set as close as possible to the accelerometers' offset voltage to minimize the delay between ball impact and the triggering of the conversion sequence, but enough clearance must be provided to prevent false triggering due to noise. Because the comparator network is wired such that any one of the accelerometer outputs can trigger it, the threshold voltage must be higher than the highest accelerometer offset voltage. Hysteresis is not necessary for the comparator network, because 2-92 once the MCU goes into the conversion sequence it ignores the input capture pin. The system is powered using a commercially available 9 V supply. A Motorola MC7805 voltage regulator is used to provide a steady 5 Volt supply for the operation of the MCU, the accelerometers, the comparator network, and the op-amp buffers. The 9 V supply is directly connected to the common anode 8-segment LED displays. Each segment can draw as much as 30 mA of current. Therefore, to ensure proper operation, the power supply selected to build this circuit should be capable of supplying at least 600 mA. Ports B and C on the MCU are used to drive the LED displays. Each port output pin is connected via a resistor to the base of a BJT, which has the emitter tied to ground. A current limiting resistor is connected between the collector of each BJT and the cathode of the corresponding segment on the display. To minimize the amount of board space consumed by the output driving circuitry, MPQ3904s (quad packaged 2N3904s) were selected instead of the standard discrete 2N3904s. The zero bit on Port C is connected to a combination BJT and MOSFET circuit that drives the "Your Speed" and "Best Speed" LED's. The circuit is wired so that the LED's toggle, and only one can be ON at a time. Figure 4 shows a schematic of the circuit used. Part (a) shows the accelerometers, the op-amps used to buffer the outputs and drive the transmission lines, the comparator network and the potentiometer used to set the detection threshold. Part (b) shows the MCU, with its minimal required supporting circuitry. Part (c) shows the voltage regulator, a mapping of the cathodes to the corresponding segments on the LED displays, the BJT switch circuitry used to drive the seven segment display LEDs (although not shown on the schematic, this circuit block is actually repeated 15 times), and finally, the circuitry used to drive the "Your Speed"/"Best Speed" LEDs. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1635 VCC VCC U1 VCC ACCELEROMETER VCC 4 ST 8 VDD C1 0.1 mF VOUT 5 R1 1 k C5 0.01 mF 7 VSS 3 2 + R5 10 k 6 U5 - 4 8 2 + 7 3 - 7 U9 1 4 MC33201 LM311 PA2/IC1 R6 1 k C9 0.01 mF PE4/AN4 VCC U2 VCC ACCELEROMETER Freescale Semiconductor, Inc... VCC C2 0.1 mF 4 ST 8 VDD VOUT 5 R2 1 k C6 0.01 mF 7 VSS 3 2 + 6 U6 - 4 8 2 + 7 3 - 7 U10 1 4 MC33201 LM311 PE5/AN5 VCC U3 VCC ACCELEROMETER VCC C3 0.1 mF 4 ST 8 VDD VOUT 5 R3 1 k C7 0.01 mF 7 VSS 3 2 + 6 U7 - 4 8 2 + 7 3 - 7 U11 1 4 MC33201 LM311 PE6/AN6 VCC U4 VCC ACCELEROMETER VCC C4 0.1 mF 4 ST 8 VDD 7 VSS VOUT 5 R4 1 k C8 0.01 mF 3 2 + 6 U8 - 4 8 2 + 7 MC33201 3 - 7 U12 1 4 LM311 VCC R7 20 k PE7/AN7 C10 1 mF Figure 4a. Accelerometers, Buffer Op-Amps, and Comparator Network Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-93 Freescale Semiconductor, Inc. AN1635 U14 MC68HC11E9 VCC E 26 VDD C13 0.1 F C12 4.7 F 1 7 10 M R11 8 VSS EXTAL XTAL Freescale Semiconductor, Inc... 8 MHz C15 C14 VCC 18 pF 18 pF VCC PA0/IC3 PA1/IC2 PA2/IC1 PA3/IC4/OC5/OC1 PA4/OC4/OC1 PA5/OC3/OC1 PA6/OC2/OC1 PA7/PAI/OC1 PB0/A8 PB1/A9 PB2/A10 PB3/A11 PB4/A12 PB5/A13 PB6/A14 PB7/A15 STRB/R/W* R10 R8 4.7 k 17 RESET* 4.7 k U13 VCC MC34164P 2 IN RST* 1 R12 GND R13 4.7 k 18 4.7 k 19 3 4.7 k R14 R9 200 k C11 1 F 2 3 RESET XIRQ* IRQ* MODB/VSTBY MODA/LIR* VCC R15 1 k 52 C16 1 F 51 VRH VRL STRA/AS PC0/AD0 PC1/AD1 PC2/AD2 PC3/AD3 PC4/AD4 PC5/AD5 PC6/AD6 PC7/AD7 PD0/RxD PD1/TxD PD2/MISO PD3/MOSI PD4/SCK PD5/SS* PE0/AN0 PE1/AN1 PE2/AN2 PE3/AN3 PE4/AN4 PE5/AN5 PE6/AN6 PE7/AN7 5 34 33 32 31 30 29 28 27 42 41 40 39 38 37 36 35 PA2/IC1 "Your'' / "Best'' F G E D Ones Digit C LED Display B A 6 4 9 10 11 12 13 14 15 16 DP F G E D C B A Tens Digit LED Display 20 21 22 23 24 25 43 45 47 49 44 46 48 50 PE4/AN4 PE5/AN5 PE6/AN6 PE7/AN7 Figure 4b. MC68HC11E9 MCU with Supporting Circuitry 2-94 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1635 B+ U15 3 +9 VDC P.S. MC78L05ACP VIN C17 1F 1 VOUT VCC C18 1F GND 2 GND P.S. B+ A 1/8 LED Display Freescale Semiconductor, Inc... F B R32 - R46 180 G E R16 - R30 10 k C D U16-U19 MPQ3904 From PB or PC DP VCC "Best Speed'' VCC "Your Speed'' R48 1 k R47 1 k U20 VN0300L R31 10 k PB0 1/4 MPQ3094 Figure 4c. Voltage Regulator, LED Segment Mapping, and LED Driving Circuitry Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-95 AN1635 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... IMPLEMENTATION -- SOFTWARE The operation of the Baseball Pitch Speedometer is very simple. Upon power on reset, the output LEDs are initialized to display "00" and "Best Speed." The analog to digital converter is turned on and the offset voltages of the accelerometers are measured and stored. Finally, all the variables are initialized and the MCU goes into a dormant state, where it will wait for a negative edge input capture pulse to trigger it to begin processing the crash signal. Once the input capture flag is set, the MCU will immediately begin the analog to digital conversion sequence. As it digitizes the crash signature, it will calculate the absolute difference between the current value and the stored offset voltage value. It will integrate by summing up all the differences. Figure 2 shows a typical crash signature of the Baseball Pitch Speedometer. As illustrated, starting at the point of impact (A), the acceleration will initially ramp up, reaching a maximum, then decrease as the target is displaced. Because the target is constrained to the frame structure, the acceleration will continue to decrease until it reaches a minimum (point B), which correspond to the travel stop of the target. It is difficult to determine exactly when point B will occur, because the amplitude and duration of the initial acceleration pulse will vary with ball speed. Therefore, the capture window duration is set so that it will encompass most typical crash signatures, while rejecting most of the secondary ripples that result as the energy is dissipated by the system. After integrating the four signals, the results are added together to produce an overall sum. This procedure averages out the individual responses and reduces measurement error due to the variability of where the ball lands on the target. The MCU then divides the grand sum by an empirically predetermined constant of proportionality. The result will then go through a binary to BCD conversion algorithm. A look-up table is used to match the BCD numbers to their corresponding 7-segment display codes. The calculated speed is displayed on the two digit 8-segment displays (one segment corresponds to the decimal point), and the "Your Speed" LED is 2-96 turned on while the "Best Speed" LED is turned off. After a duration of approximately five seconds, the LEDs are toggled and stored best speed is redisplayed. The five second delay is used to provide enough time for the user to check his/her speed and also to allow the target to return to a rest state. The system is now ready for another pitch. A complete listing of the software is presented in the Appendix. CONCLUSION The Baseball Pitch Speedometer works fairly well, with an accuracy of +/- 5 mph. The dynamic range of the system is also worthy of note, measuring speeds from less than 10 mph up to well above the 70 mph range. One key point to emphasize, is that the system is empirically calibrated, and so to maintain good accuracy the system should only be used with balls of mass equal to those used during calibration. Although intended mainly for training and recreational purposes, the Baseball Pitch Speedometer demonstrates a very important concept concerning the use of accelerometers. Accelerometers can be used not only to detect that an event such as impact or motion has occurred, but more importantly they measure the intensity of such events. They can be used to discern between different crash levels and durations. This is very useful in applications where it is desired to have the system respond in accord with the magnitude of the input being monitored. An example application would be a smart air bag system, where the speed at which the bag inflates is proportional to the severity of the crash. The deployment rate of the airbag would be controlled so that it does not throw the occupant back against the seat, thus minimizing the possibility of injury to the occupant. Another application where this concept may be utilized is in car alarms, where the response may range from an increased state of readiness and monitoring, to a full alarm sequence depending on the intensity of the shock sensed by the accelerometer. This could be used to prevent unnecessary firing of the alarm in the event that an animal or person were to inadvertently bump or brush against the automobile. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1635 APPENDIX -- ASSEMBLY CODE LISTING FOR BASEBALL PITCH SPEEDOMETER Freescale Semiconductor, Inc... * Baseball Pitch Speedometer - Rev. 1.0 * * Program waits for detection of impact via the input capture pin and then reads four A/D channels. * The area under the Acceleration vs. Time curve is found by subtracting the steady state offsets * from the digitized readings and summing the results. The sum is then divided by an empirically * determined constant of proportionality, and the speed of the ball is displayed. * * Written by Carlos Miranda * Systems and Applications * Sensor Products Division * Motorola Semiconductor Products Sector * May 6, 1997 * * ******************************************************************************************************** * Although the information contained herein, as well as any information provided relative * * thereto, has been carefully reviewed and is believed accurate, Motorola assumes no * * liability arising out of its application or use, neither does it convey any license under * * its patent rights nor the rights of others. * ******************************************************************************************************** * These equates assign memory addresses to variables. EEPROM EQU $B600 CODEBGN EQU $B60D REGOFF EQU $1000 ;Offset to access registers beyond direct addressing range. PORTC EQU $03 PORTB EQU $04 DDRC EQU $07 TCTL2 EQU $21 TFLG1 EQU $23 ADCTL EQU $30 ADR1 EQU $31 ADR2 EQU $32 ADR3 EQU $33 ADR4 EQU $34 OPTION EQU $39 STACK EQU $01FF ;Starting address for the Stack Pointer. RAM EQU $0000 * These equates assign specific masks to variables to facilitate bit setting, clearing, etc. ADPU EQU $80 ;Power up the analog to digital converter circuitry. CSEL EQU $40 ;Select the internal system clock. CCF EQU $80 ;Conversion complete flag. IC1F EQU $04 ;Input Capture 1 flag. IC1FLE EQU $20 ;Configure Input Capture 1 to detect falling edges only. IC1FCLR EQU $FB ;Clear the Input Capture 1 flag. CHNLS47 EQU $14 ;Select channels 4 through 7 with MULT option ON. SAMPLES EQU $0200 ;Number of A/D samples taken. OC1F EQU $80 ;Output Compare 1 flag. OC1FCLR EQU $7F ;Clear the Output Compare flag. CURDLY EQU $0098 ;Timer cycles to create delay for displaying "Your Speed." RAMBYTS EQU $19 ;Number of RAM variables to clear during initialization. ALLONES EQU $FF YOURSPD EQU $01 PRPFCTR EQU $00AD ;This constant of proportionality was empirically determined. * Variables used for computation. ORG RAM OFFSET1 RMB 1 ;One for each accelerometer. OFFSET2 RMB 1 OFFSET3 RMB 1 OFFSET4 RMB 1 SUM1 RMB 2 ;Area under the acceleration vs. time curve. SUM2 RMB 2 SUM3 RMB 2 SUM4 RMB 2 GRNDSUM RMB 2 COUNT RMB 2 CURBIN RMB 1 TEMPBIN RMB 1 BCD RMB 2 CURDSPL RMB 2 MAXBIN RMB 1 MAXDSPL RMB 2 * LED seven segment display patterns table. ORG EEPROM JMP START SEVSEG FCB %11111010 FCB %01100000 FCB %11011100 FCB %11110100 FCB %01100110 FCB %10110110 FCB %10111110 FCB %11100000 FCB %11111110 FCB %11100110 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-97 Freescale Semiconductor, Inc... AN1635 Freescale Semiconductor, Inc. * This is the main program loop. ORG CODEBGN START LDS #STACK LDX #REGOFF JSR LEDINIT JSR ADCINIT JSR VARINIT MAIN JSR CAPTURE JSR COMPUTE JSR BINTBCD JSR OUTPUT BRA MAIN * This subroutine initializes ports B & C, and the LED display. LEDINIT PSHX PSHA LDX #REGOFF BSET DDRC,X,ALLONES ;Configure port C as an output. LDAA SEVSEG STAA PORTB,X STAA PORTC,X PULA PULX RTS * This subroutine initializes the analog to digital converter. ADCINIT PSHX PSHA LDX #REGOFF BSET OPTION,X,ADPU ;Turn on A/D converter via ADPU bit. BCLR OPTION,X,CSEL ;Select system e clock via CSEL bit. CLRA DELAY INCA BNE DELAY PULA PULX RTS * This subroutine clears all the memory variables. VARINIT PSHX LDX #$0000 CLRVAR CLR OFFSET1,X INX CPX #RAMBYTS ;Number of RMB bytes. BLO CLRVAR DONECLR LDX #REGOFF LDAA #CHNLS47 ;Measure the offset. STAA ADCTL,X OFSWAIT BRCLR ADCTL,X,CCF,OFSWAIT LDD ADR1,X STD OFFSET1 LDD ADR3,X STD OFFSET3 PULX RTS * This subroutine waits for impact and computes the area under the curve. CAPTURE PSHX PSHA PSHB LDX #REGOFF BSET TCTL2,X,IC1FLE ;Set IC1 to detect falling edge only. BCLR TFLG1,X,IC1FCLR MONITOR BRCLR TFLG1,X,IC1F,MONITOR ADCREAD LDAA #CHNLS47 ;Select channels 4 - 7 for conversion. STAA ADCTL,X ADCWAIT BRCLR ADCTL,X,CCF,ADCWAIT CALDLT1 LDAB ADR1,X SUBB OFFSET1 BPL ADDSUM1 COMB INCB ADDSUM1 CLRA ADDD SUM1 STD SUM1 CALDLT2 LDAB ADR2,X SUBB OFFSET2 BPL ADDSUM2 COMB INCB ADDSUM2 CLRA ADDD SUM2 STD SUM2 CALDLT3 LDAB ADR3,X SUBB OFFSET3 BPL ADDSUM3 COMB INCB 2-98 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1635 Freescale Semiconductor, Inc... ADDSUM3 CLRA ADDD SUM3 STD SUM3 CALDLT4 LDAB ADR4,X SUBB OFFSET4 BPL ADDSUM4 COMB INCB ADDSUM4 CLRA ADDD SUM4 STD SUM4 LDD COUNT ADDD #$0001 STD COUNT CPD #SAMPLES BLO ADCREAD PULB PULA PULX RTS * This subroutine computes the ball speed by dividing the overall sum by a constant. COMPUTE PSHX PSHA PSHB LDD SUM1 ADDD SUM2 ADDD SUM3 ADDD SUM4 STD GRNDSUM LDX #PRPFCTR IDIV XGDX STAB CURBIN PULB PULA PULX RTS * This subroutine converts from binary to BCD. (Limited to number up to 99 decimal.) BINTBCD PSHX PSHA PSHB LDX #$0000 LDAA CURBIN STAA TEMPBIN CLRA CLRB BINSHFT LSL TEMPBIN ROLB LSLA CMPB #$10 BLO CHKDONE INCA ANDB #$0F CHKDONE INX CPX #$0008 BEQ RAILAT9 CHKFIVE CMPB #$05 BLO BINSHFT ADDB #$03 BRA BINSHFT RAILAT9 CMPA #$09 ;Force the display to "99" if speed > 100 mph. BLS DONE LDD #$0909 DONE STD BCD LDX #SEVSEG ;This part finds the seven segment display codes. XGDX ADDB BCD XGDX LDAA $00,X STAA CURDSPL LDX #SEVSEG XGDX ADDB BCD+1 XGDX LDAA $00,X STAA CURDSPL+1 PULB PULA PULX RTS * This subroutine displays the current speed for 5 seconds & then displays the maximum. OUTPUT PSHX PSHA PSHB Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-99 Freescale Semiconductor, Inc. AN1635 OLDMAX LEDWAIT DSPLDLY Freescale Semiconductor, Inc... RECLEAR 2-100 LDX LDAA CMPA BLS STAA LDD STD LDD STD BSET LDD BCLR BRCLR ADDD CPD BLO LDX CLR INX CPX BLO LDX LDD STD PULB PULA PULX RTS #REGOFF CURBIN MAXBIN OLDMAX MAXBIN CURDSPL MAXDSPL CURDSPL PORTC,X PORTB,X,YOURSPD ;Toggle the "YOUR"/"BEST" LEDs. #$0000 TFLG1,X,OC1FCLR ;Clear output compare 1 flag. TFLG1,X,OC1F,DSPLDLY #$0001 #CURDLY ;Decimal 152. (152 * 33ms = 5.0 sec) LEDWAIT #$0000 SUM1,X ;Clear 12 RAM bytes beginning at address "SUM1". ;Clears SUM1 thru SUM4, GRNDSUM, and COUNT. #$000C RECLEAR #REGOFF MAXDSPL PORTC,X ;The "YOUR"/"BEST" LEDS are automatically toggled. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1640 Reducing Accelerometer Susceptibility to BCI Freescale Semiconductor, Inc... Prepared by Brandon Loggins Automobile manufacturers require all system electronics to pass stringent electromagnetic compatibility (EMC) tests. Airbag systems are one of the systems that must perform adequately under EMC tests. There are different types of tests for EMC, one of which is testing the tolerance of the system to high frequency conducted emissions. One of the most stringent methods for EMC evaluation is the Bulk Current Injection (BCI) test. The entire airbag system must continue to function normally throughout the BCI test. This application note will discuss how to reduce susceptibility to BCI for the Motorola accelerometer but the information presented here can be applied to other electronic components in the system. BCI TEST SETUP The BCI test procedure follows a published SAE engineering standard, "Immunity to Radiated Electric Fields ~ Bulk Current Injection (BCI)", or SAE J 1113/401. For an airbag module, this involves injecting the desired current into the wiring harness by controlling current in the injection probe. The test frequency can vary from one to several hundred MHz. There are at least 20 frequency steps per octave required for the test, but as many as 50 steps per octave can be used. The injection probe is placed on the harness in one of three distances from the airbag module connector: 120, 450 and 750 mm. There is a monitor pickup probe present to measure the amount of current being injected. It is placed 50 mm from the airbag module. This feeds back to the system to ensure that the desired test current is being injected on to the wiring harness. Figure 1 shows the setup for the BCI test. (For more details, see the SAE J 1113/401 Test Procedure). 70, 450, or 750 mm ANECHOIC CHAMBER WALL 50 mm AIRBAG MODULE WIRING HARNESS PC LOAD BOX PICKUP PROBE INJECTION PROBE BASEPLATE CONNECTED TO GROUND Figure 1. BCI Test Setup The harness connects the airbag module to a load box. This load box provides simulated loads for terminating the remainder of the airbag system (firing ignitors, etc.). The data coming back is translated from J1850 to RS232 to be communicated to a dummy terminal on a PC. For safety reasons, this test is typically performed inside an anechoic chamber to shield high frequency emissions from equipment and humans. BCI TEST PROCEDURE FOR THE MMA2202D ACCELEROMETER The accelerometer is evaluated in the following manner. In an airbag system, the microcontroller's A/D converter digitizes the accelerometer output. The microcontroller sends this value to the communication ASIC which translates the logic from board level logic to RS232, then sends the value back REV 2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-101 Freescale Semiconductor, Inc... AN1640 Freescale Semiconductor, Inc. along the wiring harness. Once through the chamber wall, the data is translated to RS232 and fed to a dummy terminal. On the terminal screen, the A/D codes for the accelerometer can be monitored for unexpected performance. Ideally, when the accelerometer is at rest (no acceleration applied), the output should be at 0g, regardless of what EMC testing the system may be subjected to. Depending on the crash algorithm of the airbag module software, there is some allowable offset shift that can be tolerated. Higher shift in output could create errors in the crash analysis software, perhaps causing the airbags to unnecessarily deploy when there is not a crash or not deploy when there is a crash. The Motorola accelerometer must be able to meet the airbag system requirements throughout BCI exposure. It has a sensitivity of 40 mV/g and an offset (0g output) of 2.50 V. During the BCI test, the accelerometer output should be 2.50 V at 0g with as little drift as possible. A typical airbag system may have software that can tolerate from as little as 0.5 g up to 2.0 g. of deviation from the offset. The system would then expect the accelerometer output to be within 40 mV of the offset during the entire BCI test. Therefore, at any given frequency of the BCI test, if the output deviates outside this expected window of drift, it fails the test. MMA2202D ACCELEROMETER BCI TEST RESULTS If a system has not been well designed for electromagnetic compatibility, the accelerometer, as well as other devices, can have performance problems. What has been found for the accelerometer is that in some system applications, it suffers from an offset shift when certain frequencies of BCI are applied. For example, in one airbag system being tested at a certain frequency, with the desired BCI current applied, the offset is found to shift down by 60 mV. This would equate to an error of 1.5 g. See Figure 2. At other frequencies, this shift is even higher. This DC shift plot was taken with an oscilloscope using a 20 MHz filter to remove the high frequency component of the signal. Probes are placed at the accelerometer in the system application. The plot shows the accelerometer output before and after BCI was applied (before and after the RF generator creating the high frequency signal was turned on). ACCELEROMETER VOUT w/o BCI ACCELEROMETER VOUT w/BCI VCC Figure 2. Accelerometer Tested Under High Frequency BCI This phenomenon has been determined to be system level related. PCB layout and grounding for the accelerometer will affect its performance. This was found by testing the accelerometer outside of the airbag module. The device was put on a test board by itself with only the supply decoupling capacitor of 0.1 F connected to it. To simulate the effect of BCI on Vcc, a frequency generator was used to inject a known high frequency sinusoid that caused BCI failure on to the 5.0 V supply voltage. The device was first tested in small test board with ground provided by one wire back to the supply. This grounding reproduced the failure due to BCI seen at the 2-102 module level. The test board was then mounted down to a ground plane provided by a copper plate and the accelerometer ground was soldered to the plate (providing a low impedance path to ground). With this setup, the offset shift did not occur. If a system does not incorporate a good PCB layout providing a low impedance to ground, the accelerometer output may shift at certain high frequencies. This output offset shift was caused by a shift in the 0-5 V supply window. Because the accelerometer has a ratiometric output, its offset is dependent on the supply voltage. Any change in the supply For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. voltage will result in the same proportional change in the output. For example, if the 5 V supply were to change by 10%, from 5.0 V to 5.5 V, the accelerometer offset will change by 10% also, from 2.5 V to 2.75 V. This phenomena would also occur if the ground were to shift. A 100 mV change in ground would result in a 50 mV change in the output. If the accelerometer does not have low impedance path to ground and parasitics from a poor ground are present as a result, the ground seen by the accelerometer may change over frequency. So, during a BCI test, if the 5.0 V supply does not shift but the output of the accelerometer does, the ground to the accelerometer may be moving. It was found with some experimentation that the offset shift can be eliminated with proper board layout techniques as described below. Freescale Semiconductor, Inc... PROPER LAYOUT TECHNIQUES Since the Motorola accelerometer is a sensitive analog device that relies on a clean supply to function within established parameters, there are some techniques that can be employed to minimize the effects of BCI on the accelerometer performance. PCB layout is paramount to reducing susceptibility to BCI. * A low impedance path to ground will provide shunting of the high frequency interference and minimize its effect on the accelerometer. The best way to provide a good path is by putting a solid, unbroken ground plane in the PCB. This ground plane should be shunted to chassis ground at the module connector. This will ensure that the high frequency BCI will be shunted before interfering with accelerometer performance. * All accelerometer pins that require ground connection should be tied together to a common ground. * Traces attached directly to the connector pins can receive high RF noise, which can couple to nearby traces and components. Increasing series impedance of the traces helps reduce the couple or conducted noise. High frequency filters on the supply line and other susceptible lines may be required to filter out high frequency interference introduced by the BCI test. Signal lines that carry low current can tolerate series resistances of 100-200 . * Decoupling capacitors on every input line to the common ground plane will help shunt the high frequency away from the system. These should be placed near the connector. Motorola Sensor Device Data AN1640 * Signal trace lengths to and from the accelerometer should be kept at a minimum. The shorter the trace, the less chance it has of picking up high frequency BCI signals as it crosses the board. Trace lengths can be reduced by placing the accelerometer and the microcontroller as close together as possible. Signal and ground traces looping should be minimized. * A decoupling capacitor on the accelerometer Vcc pin will also help minimize BCI effects. The recommended value is 0.1 F. This capacitor should be placed as close as possible to the accelerometer to achieve the best results. * To maximize ratiometricity, the accelerometer Vcc and the microcontroller A/D reference pin should be on the same trace. The accelerometer ground and the microcontroller ground should also share the same ground point. Therefore, when there is signal interference due to BCI, the A/D converter and the accelerometer will see the interference at the same level. This will result in the same digital code representation of acceleration without signal interference. * A clean power supply to both the accelerometer and the microcontroller should be provided. Supply traces should avoid high current traces that might carry high RF currents during the BCI test. The traces should be as short as possible. * The accelerometer should be placed on the opposite end of the PCB away from the connector. The farther the distance, the lower the chance high frequency RF from BCI will interfere with the accelerometer. * The accelerometer should be placed away from high current paths that may carry high RF currents during the BCI test. Automotive customers will continue to require airbag systems to have high standards for EMC. One way to test for EMC is perform the Bulk Current Injection test. Because of the high current involved, BCI is one of the most difficult EMC tests to pass. Being part of the airbag system, the accelerometer must continue to function normally under application of high frequency BCI. The accelerometer is highly sensitive to placement on the board and its connection to ground. Poor design will caused the device to fail the BCI test. The practice of good PCB layout, device placement and good grounding will allow the accelerometer to function within specification and pass the BCI test. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-103 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1925 Using the Motorola Accelerometer Evaluation Board Prepared by: Leticia Gomez and Raul Figueroa Sensor Products Division Systems and Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION This application note describes the Motorola Accelerometer Evaluation Board (Figure 1). The Accelerometer Evaluation Board is a small circuit board intended to serve as an aid in system design with the capability for mounting the following devices: MMA1220D, MMA1201P, MMA1200D, MMA2201D. This evaluation board is useful for quickly evaluating any of these three devices. It also provides a means for understanding the best mounting position and location of an accelerometer in your product. CIRCUIT DESCRIPTION Figure 2 is a circuit schematic of the evaluation board. The recommended decoupling capacitor at the power source and recommended RC filter at the output, are included on the evaluation board. This RC filter at the output of the accelerometer minimizes clock noise that may be present from the switched capacitor filter circuit. No additional components are necessary to use the evaluation board. Refer to the respective datasheet of the device being used for specifications and technical operation of the accelerometer. The evaluation board has a 4-pin header (J1 in Figure 1) for interfacing to a 5 volt power source or a 9 to 15 volt power Jumper (JP1) Mounting Hole (1 of 4) source (for example, 9 V battery). Jumper JP1 (see Figure 1) must have the following placement: on PS if a 5 V supply is being used or on BATT if a 9 V to 15 V supply is used. A 5 V regulator (U1 in figure 1) supplies the necessary power for the accelerometer in the BATT option. The power header also provides a means for connecting to the accelerometer analog output through a wire to another breadboard or system. Four through-hole sockets are included to allow access to the following signals: VDD, GND, ST and STATUS. These sockets can be used as test points or as means for connecting to other hardware. The ON/OFF switch (S1) provides power to the accelerometer and helps preserve battery life if a battery is being used as the power source. S1 must be set towards the "ON" position for the accelerometer to function. The green LED (D1) is lit when power is supplied to the accelerometer. A self-test pushbutton (S2) on the evaluation board is a self-test feature that provides verification of the mechanical and electrical integrity of the accelerometer. The STATUS pin is an output from the fault latch and is set high if one of the fault conditions exists. A second pressing of the pushbutton (S2) resets the fault latch, unless of course one or more fault conditions continue to exist. 5 V Regulator (U1) PS Power Header (J1) MMA Device Accelerometer Output (Vout) STATUS On/Off Switch (S1) Self-Test Pushbutton (S2) BATT Test Points Power LED (D1) Figure 1. Motorola Accelerometer Evaluation Board REV 0 2-104 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1925 VDD MMA1220D S2 MC78L05 4 3 9 V to 15 V J1 1 IN .1 F C1 OUT GND 2 ST VOUT .33 F C2 ON VDD +5 V J1 PS S1 JP1 VDD .01 F C3 750 R1 5 STATUS VOUT 1K R2 8 BATT OFF VOUT J1 .01 F C4 TP3 6 STATUS TP2 VSS 7 D1 Green LED Freescale Semiconductor, Inc... Figure 2. Evaluation Board Circuit Schematic SOIC MMA Device Unused pins 20-pin Test Socket Bottom Lid Snap Pin 1 Figure 3. Motorola Accelerometer Evaluation Board with Test Socket The board allows for direct mounting of a 16-pin DIP or SOIC package. For the SOIC device, a 20-pin test socket is used to allow for evaluation of more than one device without soldering directly to the board and potentially damaging the PCB. Care must be taken in placing the device correctly in the socket as four pins of the socket will not be used. With the board oriented as shown in Figure 3, Pin 1 should face downward and the device should be positioned toward the top of the test socket, thereby exposing the bottom four pins of the test socket. The socket is marked to help identify the 4 unused socket pins. Lids to secure the device in the socket are included with the board and delicately snap into place. The lids Motorola Sensor Device Data can be removed by applying pressure to the sides of the lid or by lifting the top and bottom snaps of the lid. PIN OUT DESCRIPTION Pin Name Description 4 ST 5 VOUT 6 STATUS 7 VSS Power supply ground 8 VDD Power supply input www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Logic input pin to initiate self-test Output voltage of the accelerometer Logic output pin to indicate fault 2-105 AN1925 Freescale Semiconductor, Inc. Figures 4 and 5 show the layout used on the evaluation board. Through-hole mounting components have been selected to facilitate component replacement. It is important to maintain a secure mounting scheme to capture the true motion. Orientation of the sensor is also crucial. For best results, align the sensitive axis of the accelerometer to the axis of vibration. In the case of the MMA1220D, the sensitive axis is perpendicular to the plane of the evaluation board. MOUNTING CONSIDERATIONS SUMMARY System design and sensor mounting can affect the response of a sensor system. The placement of the sensor itself is critical to obtaining the desired measurements. It is important that the sensor be mounted as rigidly as possible to obtain accurate results. Since the thickness and mounting of the board varies, parasitic resonance may distort the sensor measurement. Hence, it is vital to fasten and secure to the largest mass structure of the system, i.e. the largest truss, the largest mass, the point closest to source of vibration. On the other hand, dampening of the sensor device can absorb much of the vibration and give false readings as well. The evaluation board has holes on the four corners of the board for mounting. The Accelerometer Evaluation Board is a design-in tool for customers seeking to quickly evaluate an accelerometer in terms of output signal, device orientation, and mounting considerations. Both through-hole and surface mount packages can be evaluated. With the battery supply option and corner perforations, the board can easily be mounted on the end product; such as a motor or a piece of equipment. Easy access to the main pins allows for effortless interfacing to a microcontroller or other system electronics. The simplicity of this evaluation board provides reduced development time and assists in selecting the best accelerometer for the application. Freescale Semiconductor, Inc... BOARD LAYOUT AND CONTENT Figure 4. Board Layout (Component Side) 2-106 Figure 5. Board Layout (Back Side) For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Case Outlines A A G/2 2 PLACES, 16 TIPS G 16 NOTES: 1. ALL DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DIMENSIONS "A" AND "B" DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.15 PER SIDE. 4. DIMENSION "D" DOES NOT INCLUDE DAMBAR PROTRUSION. PROTRUSIONS SHALL NOT CAUSE THE LEAD WIDTH TO EXCEED 0.75 0.15 T A B 9 B P 1 B 8 16X D 0.13 T A B M Freescale Semiconductor, Inc... R X 45 _ J C 0.1 K T DIM A B C D F G J K M P R M F SEATING PLANE CASE 475-01 ISSUE B 16 LEAD SOIC -A- 20 11 P10 PL 0.13 (0.005) -B- 1 M T A M B M 10 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.13 (0.005) TOTAL IN EXCESS OF D DIMENSION AT MAXIMUM MATERIAL CONDITION. D 16 PL 0.13 (0.005) M T A M B M R X 45 _ J C -T- SEATING PLANE MILLIMETERS MIN MAX 10.15 10.45 7.40 7.60 3.30 3.55 0.35 0.49 0.76 1.14 1.27 BSC 0.25 0.32 0.10 0.25 0_ 7_ 10.16 10.67 0.25 0.75 K G F M DIM A B C D F G J K M P R MILLIMETERS MIN MAX 12.67 12.96 7.40 7.60 3.30 3.55 0.35 0.49 0.76 1.14 1.27 BSC 0.25 0.32 0.10 0.25 0_ 7_ 10.16 10.67 0.25 0.75 INCHES MIN MAX 0.499 0.510 0.292 0.299 0.130 0.140 0.014 0.019 0.030 0.045 0.050 BSC 0.010 0.012 0.004 0.009 0_ 7_ 0.400 0.420 0.010 0.029 CASE 475A-01 ISSUE O 20 LEAD SOIC Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-107 Freescale Semiconductor, Inc. A B A 12 C Y 7 NOTES: 1. DIMENSIONS ARE IN INCHES. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. PLANE -X- AND PLANE -Y- SHOULD BE ALIGNED WITHIN 0.0015". B 1 8X 8X J D T A M 6X U 0.005 G M DIM A B C D G H J K L M N P S U L K U H M " Y 6 S B N M T CASE 456-06 ISSUE J WB PACKAGE A C N F T E G 16X 0.005 (0.13) 2-108 M SEATING PLANE 0.005 (0.13) J 8 16X 1 L 9 B 16 M M T B B A K Freescale Semiconductor, Inc... P INCHES MIN MAX 0.618 0.638 0.240 0.260 0.127 0.133 0.015 0.021 0.100 BSC 0.050 BSC 0.009 0.012 0.125 0.140 0.063 0.070 0.015 0.025 0.036 0.044 0.095 0.110 0.025 0.035 0.088 0.108 NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. DIM A B C D E F G J K L M N INCHES MIN MAX 0.744 0.783 0.240 0.260 0.145 0.185 0.015 0.021 0.050 BSC 0.040 0.70 0.100 BSC 0.008 0.015 0.115 0.135 0.300 BSC 0_ 10_ 0.015 0.040 MILLIMETERS MIN MAX 18.90 19.90 6.10 6.60 3.69 4.69 0.38 0.53 1.27 BSC 1.02 1.78 2.54 BSC 0.20 0.38 2.92 3.43 7.62 BSC 0_ 10_ 0.39 1.01 D T A CASE 648C-04 ISSUE D DIP PACKAGE For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Accelerometer Glossary of Terms Acceleration Change in velocity per unit time. Acceleration Vector Vector describing the net acceleration acting upon the device. Frequency Bandwidth The accelerometer output frequency range. g A unit of acceleration equal to the average force of gravity occurring at the earth's surface. A g is approximately equal to 32.17 ft/s2 or 9.807 m/s2. Nonlinearity The maximum deviation of the accelerometer output from a point-to-point straight line fitted to a plot of acceleration vs. output voltage. This is determined as the percentage of the full-scale output (FSO) voltage at full-scale acceleration (40g). Ratiometric The variation of the accelerometer's output offset and sensitivity linearly proportional to the variation of the power supply voltage. Sensitivity The change in output voltage per unit g of acceleration applied. This is specified in mV/g. Sensitive Axis The most sensitive axis of the accelerometer. On the DIP package, acceleration is in the direction perpendicular to the top of the package (positive acceleration going into the device). On the SIP package, acceleration is in the direction perpendicular to the pins. Transverse Acceleration Any acceleration applied 90 to the axis of sensitivity. Transverse Sensitivity Error The percentage of a transverse acceleration that appears at the output. For example, if the transverse sensitivity is 1%, then a +40 g transverse acceleration will cause a 0.4 g signal to appear on the output. Transverse sensitivity can result from sensitivity of the g-cell to transverse forces. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 2-109 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 2-110 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Section Three Pressure Sensor Products Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 General Information: Device Numbering System . . . . . . . . . . . . . . . . . . 3-4 Package Offerings . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Pressure Sensor Overview Motorola's pressure sensors are silicon micromachined, electromechanical devices featuring device uniformity and consistency, high reliability, accuracy and repeatability at competitively low costs. With more than 20 years in pressure sensor engineering, technology development and manufacturing, these pressure sensors have been designed into automotive, industrial, healthcare, commercial and consumer products worldwide. Pressure sensors operate in pressures up to 150psi (1000 kPa). For maximum versatility, Motorola pressure sensors are single silicon, piezoresistive devices with three levels of device sophistication. The basic sensor device provides uncompensated sensing, the next level adds device compensation and the third and most value added pressure sensors are the integrated devices. Compensated sensors are available in temperature compensated and calibrated configurations; integrated devices are available in temperature compensated, calibrated and signal conditioned (or amplified) configurations. Each sensor family is available in gauge, absolute and differential pressure references in a variety of packaging and porting options. Motorola Sensor Device Data Orderable Part Numbers . . . . . . . . . . . . . . . . . . . . . 3-6 Pressure Sensor Overview General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7 Motorola Pressure Sensors . . . . . . . . . . . . . . . . . . . . 3-8 Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 Sensor Applications . . . . . . . . . . . . . . . . . . . . . . . . . 3-13 Pressure Sensor FAQ's . . . . . . . . . . . . . . . . . . . . . . 3-14 Data Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 Application Notes . . . . . . . . . . . . . . . . . . . . . . . . . 3-188 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-423 Reference Information Reference Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-439 Mounting and Handling Suggestions . . . . . . . . . . 3-441 Standard Warranty Clause . . . . . . . . . . . . . . . . . . . 3-442 Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . 3-443 Symbols, Terms and Definitions . . . . . . . . . . . 3-446 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-1 Freescale Semiconductor, Inc. Mini Selector Guide PRESSURE SENSORS Uncompensated Pressure Sensors Product Family Pressure Rating Maximum (psi) Pressure Rating Maximum (kPa) Pressure Rating Maximum (in H2O) Pressure Rating Maximum (cm H20) Pressure Rating Maximum (mm Hg) Offset (Typ) (mV) Full Scale Span (Typ) (mV) Sensitivity (mV/kPa) MPX10 1.45 10 40 102 75 20 35 3.5 MPX12 1.45 10 40 102 75 20 55 3.5 MPX53 7 50 200 510 375 20 60 Pressure Rating Maximum (in H2O) Pressure Rating Maximum (cm H20) Pressure Rating Maximum (mm Hg) Offset (mV) Pressure Type Note A D G 1.2 D D D D D D Full Scale Span (Typ) (mV) Sensitivity (mV/kPa) Pressure Type Note Note: A = Absolute, D = Differential, G = Gauge, V = Vacuum Freescale Semiconductor, Inc... Compensated Pressure Sensors Product Family Pressure Rating Maximum (psi) Pressure Rating Maximum (kPa) MPX2010 1.45 10 40 102 75 1.0 25 2.5 MPX2053 7 50 201 510 375 1.0 40 0.8 MPX2102 14.5 14.5 100 100 400 400 1020 750 750 2.0 1.0 40 40 0.4 0.4 D MPX2202 29 29 200 200 800 800 2040 1500 1500 1.0 1.0 40 40 0.2 0.2 D MPX2050 7 50 201 510 375 1.0 40 0.8 MPX2100 14.5 14.5 100 100 400 400 1020 750 750 2.0 1.0 40 40 0.4 0.4 D 29 29 200 200 800 800 2040 1500 1500 1.0 1.0 40 40 0.2 0.2 D MPX2200 A D G D D V D V D V D D D V D V D Note: A = Absolute, D = Differential, G = Gauge, V = Vacuum Compensated Medical Grade Pressure Sensors Product Family Pressure Rating Maximum (psi) Pressure Rating Maximum (kPa) Pressure Rating Maximum (in H2O) Pressure Rating Maximum (cm H20) Pressure Rating Maximum (mm Hg) Supply Voltage (Typ) (Vdc) Offset Maximum (mV) Sensitivity (mV/kPa) MPXC2011 1.45 10 40 102 75 10.0 1.0 n/a MPX2300 5.8 40 161 408 300 6.0 0.75 5.0 Pressure Type Note A D G D D Note: A = Absolute, D = Differential, G = Gauge, V = Vacuum 3-2 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PRESSURE SENSORS (continued) Integrated Pressure Sensors Freescale Semiconductor, Inc... Product Family Pressure Rating Maximum (psi) Pressure Rating Maximum (kPa) Pressure Rating Maximum (in H2O) Pressure Rating Maximum (cm H2O) Pressure Rating Maximum (mm Hg) Full Scale Span (Typ) (Vdc) Sensitivity (mV/kPa) Accuracy 0_C-85_C (% of VFSS) MPX4080 11.6 80 321 815 600 4.3 54 3.0 MPX4100 15.2 105 422 1070 788 4.6 54 1.8 MPX4101 14.8 102 410 1040 765 4.6 54 1.8 MPXH6101 14.8 102 410 1040 765 4.6 54 1.8 MPX4105 15.2 105 422 1070 788 4.6 51 1.8 MPX4115 16.7 115 462 1174 863 4.6 46 1.5 16.7 115 462 1174 863 4 38 1.5 MPX6115 16.7 115 462 1174 863 4.6 46 1.5 MPX4200 29 200 803 2040 1500 4.6 26 1.5 MPX4250 36 250 1000 2550 1880 4.7 20 1.5 36 250 1000 2550 1880 4.7 19 1.4 MPXV4006 0.87 6 24 61 45 4.6 766 5.0 MPXV5004 0.57 4 16 40 29 3.9 1000 2.5 MPX5010 1.45 10 40 102 75 4.5 450 5.0 MPX5050 7.25 50 201 510 375 4.5 90 2.5 MPX5100 14.5 100 401 1020 750 4.5 45 2.5 16.7 115 462 1174 863 4.5 45 2.5 MPX5500 72.5 500 2000 5100 3750 4.5 9 2.5 MPX5700 102 700 2810 7140 5250 4.5 6 2.5 MPX5999 150 1000 4150 10546 7757 4.5 5 2.5 MPXH6300 44 300 1200 3060 2250 4.7 16 1.8 Pressure Type Note A D G D D D D D D V D D D D D D D D D D V V V D D D D D D D D D D Note: A = Absolute, D = Differential, G = Gauge, V = Vacuum Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-3 Freescale Semiconductor, Inc. Device Numbering System for Pressure Sensors M PX A 2 XXX A P X T1 PRESSURE SENSORS LEADFORM OPTIONS PACKAGE TYPE CATEGORY M Qualified standard S Custom device P,X Prototype device None A/V AZ Unibody Small outline package (SOP) Small outline media resistant package Chip pak Super small outline package (SSOP) M-Pak Super small outline package (TPMP) C H Freescale Semiconductor, Inc... M Y NONE No leadform 0 Open 1 thru 2 (Consult factory) 3 thru 5 Open 6 thru 7 SOP only (6 = Gull wing/Surface mount) (7 = 87 degrees/DIP) FEATURES* SHIPPING METHOD None Trays T1 Tape and reel 1 indicates part orientation in tape U Rail PORTING STYLE None Uncompensated 2 Temperature compensated/ calibrated 3 Open 4 Temperature compensated/ calibrated/signal conditioned Automotive accuracy 5 Temperature compensated/ calibrated/signal conditioned 6 High temperature 7 Open 8 CMOS Rated pressure in kPa, except for MPX2300, expressed in mmHg. C P Axial port (small outline package) Ported Single port (AP, GP, GVP) Dual port (DP) S Stovepipe port (unibody) SX Axial port (unibody) TYPE OF DEVICE A G D V Absolute Gauge Differential Vacuum/Gauge Note: Actual product marking may be abbreviated due to space constraints but packaging label will reflect full part number. *Only applies to qualified and prototype devices. This does not apply to custom devices. Examples: MPX10DP 10 kPa uncompensated, differential device in minibody package, ported, no leadform, shipped in trays. MPXA4115A6T1 115 kPa automotive temperature compensated and calibrated device with signal conditioning, SOP surface mount with gull wing leadform, shipped in tape and reel. 3-4 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. What Are the Pressure Packaging Options? Freescale Semiconductor, Inc... Pressure Sensor Packaging (Sizes not to scale) UNIBODY BASIC ELEMENT CASE 344 SUFFIX A / D UNIBODY SINGLE PORT CASE 344B SUFFIX AP / GP UNIBODY DUAL PORT CASE 344C SUFFIX DP MEDICAL CHIP PAK CASE 423A SUFFIX DT1 UNIBODY STOVEPIPE PORT CASE 344E SUFFIX AS / GS UNIBODY BASIC ELEMENT CASE 867 SUFFIX A / D UNIBODY SINGLE PORT CASE 867B SUFFIX AP / GP UNIBODY DUAL PORT CASE 867C SUFFIX DP UNIBODY AXIAL PORT CASE 867F SUFFIX ASX / GSX UNIBODY STOVEPIPE PORT CASE 867E SUFFIX AS / GS Preferred Pressure Sensor Packaging Options J SOP CASE 482 SUFFIX AG / G6 SOP AXIAL PORT CASE 482A SUFFIX AC6 / GC6 SOP SIDE PORT CASE 1369 SUFFIX AP / GP Motorola Sensor Device Data SOP CASE 482B SUFFIX G7U SOP DUAL PORT CASE 1351 SUFFIX DP SOP AXIAL PORT CASE 482C SUFFIX GC7U SOP VACUUM PORT CASE 1368 SUFFIX GVP MPAK CASE 1320 SUFFIX A / D SSOP CASE 1317 SUFFIX A6 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com MPAK AXIAL PORT CASE 1320A SUFFIX AS / GS SSOP AXIAL PORT CASE 1317A SUFFIX AC6 3-5 Freescale Semiconductor, Inc. Orderable Part Numbers PRESSURE SENSOR ORDERABLE PART NUMBERS Uncompensated Freescale Semiconductor, Inc... MPX4100A MPX4250A MPX10D MPX2102GP MPXV5004GC6T1 MPX4100AP MPX4250AP MPX10DP MPX2102DP MPXV5004GC6U MPX4100AS MPXA4250AC6T1 MPX10GP MPX2102GSX MPXV5004GC7U MPXA4100AC6U MPXA4250AC6U MPX10GS MPX2102GVP MPXV5004G6T1 MPXA4100A6T1 MPXA4250A6T1 MPXV10GC6T1 MPXM2102D MPXV5004G6U MPXA4100A6U MPXA4250A6U MPXV10GC6U MPXM2102DT1 MPXV5004G7U MPXAZ4100AC6T1 MPXH6300ACGU MPXV10GC7U MPXM2102GS MPXV5004GP MPXAZ4100AC6U MPXH6300AC6T1 MPX12D MPXM2102GST1 MPXV5004DP MPXAZ4100A6T1 MPXH6300A6U MPX12DP MPXV2102GP MPXV5004GVP MPXAZ4100A6U MPXH6300A6T1 MPX12GP MPXV2102DP MPXV4006GC6T1 MPX4101A MPX5700D MPX53D MPX2102A MPXV4006GC6U MPXA4101AC6U MPX5700DP MPX53DP MPX2102AP MPXV4006GC7U MPXH6101A6T1 MPX5700GP MPX53GP MPX2102ASX MPXV4006G6T1 MPXH6101A6U MPX5700GS MPXV53GC6T1 MPXM2102A MPXV4006G6U MPX4105A MPXV6115VC6U MPXV53GC6U MPXM2102AT1 MPXV4006G7U MPXV4115VC6U MPXAZ6115A6U MPXV53GC7U MPXM2102AS MPXV4006GP MPXV4115V6T1 MPXAZ6115A6T1 MPXM2102AST1 MPXV4006DP MPXV4115V6U MPXAZ6115AC6U MPX2300DT1 MPX2100D MPX5010D MPX5700A MPXAZ6115AC6T1 MPX2301DT1 MPX2100GP MPX5010DP MPX5700AP MPX2010D MPX2100DP MPX5010DP1 MPX5700AS MPX2010GP MPX2100GSX MPX5010GP MPX5999D MPX2010DP MPX2100GVP MPX5010GS MPX4115A MPX2010GS MPX2100A MPX5010GSX MPX4115AP MPX2010GSX MPX2100AP MPXV5010GC6T1 MPX4115AS MPXM2010D MPX2100ASX MPXV5010GC6U MPXA4115AC6T1 MPXM2010DT1 MPX2202D MPXV5010GC7U MPXA4115AC6U MPXM2010GS MPX2202GP MPXV5010G6U MPXA4115A6T1 MPXM2010GST1 MPX2202DP MPXV5010G7U MPXA4115A6U MPXC2011DT1 MPX2202GSX MPXV5010GP MPXA4115AP MPXC2012DT1 MPX2202GVP MPXV5010DP MPXAZ4115AC6T1 MPXV2010GP MPXM2202D MPX5500D MPXAZ4115AC6U MPXV2010DP MPXM2202DT1 MPX5500DP MPXAZ4115A6T1 MPX2053D MPXM2202GS MPX5050D MPXAZ4115A6U MPX2053GP MPXM2202GST1 MPX5050DP MPXA6115AC6T1 MPX2053DP MPXV2202GP MPX5050GP1 MPXA6115AC6U MPX2053GSX MPXV2202DP MPX5050GP MPXA6115A6T1 MPX2053GVP MPX2202A MPXV5050GP MPXA6115A6U MPXM2053D MPX2202AP MPXV5050DP MPXH6115A6T1 MPXM2053DT1 MPX2202ASX MPX5100D MPXH6115A6U MPXM2053GS MPXM2202A MPX5100DP MPXH6115AC6T1 MPXM2053GST1 MPXM2202AT1 MPX5100GP MPXH6115AC6U MPXV2053GP MPXM2202AS MPX5100GSX MPX4200A MPXV2053DP MPXM2202AST1 MPX5100A MPX4250D MPX2050D MPX2200D MPX5100AP MPX4250DP MPX2050GP MPX2200GP MPX4080D MPX4250GP MPX2050DP MPX2200DP MPX2050GSX MPX2200GSX Compensated MPX2102D Integrated MPX2200GVP MPX2200A MPX2200AP 3-6 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. General Product Information PRESSURE SENSOR APPLICATIONS VERSATILITY For Motorola's pressure sensors, new applications emerge every day as engineers and designers realize that they can convert their expensive mechanical pressure sensors to Motorola's lower-cost, semiconductor-based devices. Applications include automotive and aviation, industrial, healthcare and medical products and systems. Choice of Packaging: Available as a basic element for custom mounting, or in conjunction with Motorola's designed ports, printed circuit board mounting is easy. Our Small Outline and Super Small Outline packaging options provide surface mount, low profile, and top piston fit package selections. Alternate packaging material, which has been designed to meet biocompatibility requirements, is also available. 70 VS = 3.0 Vdc P1 > P2 60 +25C +125C 40 30 OFFSET (TYP) 20 10 PSI kPa 0 0 2.0 10 20 4.0 30 ACCURACY 6.0 8.0 10 40 50 60 70 12 14 16 80 90 100 PRESSURE DIFFERENTIAL Computer controlled laser trimming of on-chip calibration and compensation resistors provide the most accurate pressure measurement over a wide temperature range. Temperature effect on span is typically 0.5% of full scale over a temperature range from 0 to 85C, while the effect on offset voltage over a similar temperature range is a maximum of only 1 mV. UNLIMITED VERSATILITY Choice of Specifications: Motorola's pressure sensors are available in pressure ranges to fit a wide variety of automotive, healthcare, consumer and industrial applications. Choice of Measurement: Devices are available for differential, absolute, or gauge pressure measurements. Choice of Chip Complexity: Motorola's pressure sensors are available as the basic sensing element, with temperature compensation and calibration, or with full signal conditioning circuitry included on the chip. Uncompensated devices permit external compensation to any degree desired. Motorola Sensor Device Data - 40C 50 OUTPUT (mVdc) The performance of Motorola pressure sensors is based on its patented strain gauge design. Unlike the more conventional pressure sensors which utilize four closely matched resistors in a distributed Wheatstone bridge configuration, the device uses only a single piezoresistive element ion implanted on an etched silicon diaphragm to sense the stress induced on the diaphragm by an external pressure. The extremely linear output is an analog voltage that is proportional to pressure input and ratiometric with supply voltage. High sensitivity and excellent long-term repeatability make these sensors suitable for the most demanding applications. Figure 1. Typical Output versus Pressure Differential SPAN ERROR (% FULL SCALE) OFFSET ERROR (mV) Freescale Semiconductor, Inc... PERFORMANCE SPAN RANGE (TYP) Performance, competitive price and application versatility are just a few of the Motorola pressure sensor advantages. ERROR BAND LIMIT 2 1.5 1 0.5 SPAN ERROR 0 OFFSET ERROR - 0.5 -1 - 1.5 -2 ERROR BAND LIMIT - 50 - 25 0 25 50 75 100 125 150 TEMPERATURE (C) Curves of span and offset errors indicate the accuracy resulting from on-chip compensation and laser trimming. Figure 2. Temperature Error Band Limit and Typical Span and Offset Errors www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-7 Freescale Semiconductor, Inc. Motorola Pressure Sensors INTRODUCTION Freescale Semiconductor, Inc... Motorola pressure sensors combine advanced piezoresistive sensor architecture with integrated circuit technology to offer a wide range of pressure sensing devices for automotive, medical, consumer and industrial applications. Selection versatility includes choice of: Pressure Ranges in PSI Application Measurements 0 to 1.45, 0 to 6, 0 to 7.3, 0 to 14.5, 0 to 29, 0 to 75, 0 to 100, Absolute, Differential, Gauge 0 to 150 psi. Sensing Options Package Options Uncompensated, Temperature Compensated/Calibrated, and Signal Conditioned (with on-chip amplifiers) * Basic Element, Ported Elements for specific measurements * Surface Mount and Through Hole, Low Profile packages THE BASIC STRUCTURE MOTOROLA'S LOCALIZED SENSING ELEMENTS The Motorola pressure sensor is designed utilizing a monolithic silicon piezoresistor, which generates a changing output voltage with variations in applied pressure. The resistive element, which constitutes a strain gauge, is ion implanted on a thin silicon diaphragm. Applying pressure to the diaphragm results in a resistance change in the strain gauge, which in turn causes a change in the output voltage in direct proportion to the applied pressure. The strain gauge is an integral part of the silicon diaphragm, hence there are no temperature effects due to differences in thermal expansion of the strain gauge and the diaphragm. The output parameters of the strain gauge itself are temperature dependent, however, requiring that the device be compensated if used over an extensive temperature range. Simple resistor networks can be used for narrow temperature ranges, i.e., 0C to 85C. For temperature ranges from - 40C to +125C, more extensive compensation networks are necessary. Excitation current is passed longitudinally through the resistor (taps 1 and 3), and the pressure that stresses the diaphragm is applied at a right angle to the current flow. The stress establishes a transverse electric field in the resistor that is sensed as voltage at taps 2 and 4, which are located at the midpoint of the resistor (Figure 3a). The transducer (Figure 3) uses a single element eliminating the need to closely match the four stress and temperature sensitive resistors that form a distributed Wheatstone bridge design. At the same time, it greatly simplifies the additional circuitry necessary to accomplish calibration and temperature compensation. The offset does not depend on matched resistors but instead on how well the transverse voltage taps are aligned. This alignment is accomplished in a single photolithographic step, making it easy to control, and is only a positive voltage, simplifying schemes to zero the offset. EEEE EEEE EEEE EEE EEEE EEE EEE EE E EE S- ACTIVE ELEMENT ETCHED DIAPHRAGM BOUNDARY S+ VOLTAGE TAPS TRANSVERSE VOLTAGE STRAIN GAUGE RESISTOR 1 4 2 3 PIN # 1. GROUND 2. +VOUT 3. VS 4. -VOUT Figure 3. X-ducer Sensor Element -- Top View 3-8 S- ETCHED DIAPHRAGM BOUNDARY S+ ACTIVE ELEMENT HAS FOUR P- RESISTORS TRANSVERSE VOLTAGE STRAIN GAUGE RESISTOR 1 4 2 3 PIN # 1. GROUND 2. +VOUT 3. VS 4. -VOUT Figure 3a. Localized Sensing Element For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LINEARITY LEAST SQUARES FIT EXAGGERATED PERFORMANCE CURVE RELATIVE VOLTAGE OUTPUT Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 4) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. STRAIGHT LINE DEVIATION LEAST SQUARE DEVIATION END POINT STRAIGHT LINE FIT OFFSET Freescale Semiconductor, Inc... 0 50 100 PRESSURE (% FULLSCALE) Figure 4. Linearity Specification Comparison NEGATIVE PRESSURE VACUUM OPERATION EEEE Motorola pressure sensors provide three types of pressure measurement: Absolute Pressure, Differential Pressure and Gauge Pressure. Absolute Pressure Sensors measure an external pressure relative to a zero-pressure reference (vacuum) sealed inside the reference chamber of the die during manufacture. This corresponds to a deflection of the diaphragm equal to approximately 14.5 psi (one atmosphere), generating a quiescent full-scale output for the MPXH6101A6T1 (14.5 psi) sensor, and a half-scale output for the MPX4200A (29 psi) device. Measurement of external pressure is accomplished by applying a relative negative pressure to the "Pressure" side of the sensor. Differential Pressure Sensors measure the difference between pressures applied simultaneously to opposite sides of the diaphragm. A positive pressure applied to the "Pressure" side generates the same (positive) output as an equal negative pressure applied to the "Vacuum" side. Motorola Sensor Device Data POSITIVE PRESSURE NEGATIVE PRESSURE Absolute Sensor Differential Sensor VOFF VOFF 1 ATM PMAX INCREASING VACUUM INCREASING PRESSURE PMAX DIFFERENTIAL PRESSURE INCREASING Motorola sensing elements can withstand pressure inputs as high as four times their rated capacity, although accuracy at pressures exceeding the rated pressure will be reduced. When excessive pressure is reduced, the previous linearity is immediately restored. Figure 5. Pressure Measurements Gauge Pressure readings are a special case of differential measurements in which the pressure applied to the "Pressure" side is measured against the ambient atmospheric pressure applied to the "Vacuum" side through the vent hole in the chip of the differential pressure sensor elements. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-9 Freescale Semiconductor, Inc. Typical Electrical Characteristic Curves 100 35 OUTPUT (mVdc) 30 25 90 80 TYP MAX 20 15 10 MIN 5 0 kPa PSI -5 0 25 3.62 50 7.25 75 10.87 100 14.5 60 50 40 OUTPUT (Volts) - 40C 10 00 OFFSET (TYP) PSI 0 kPa + 125C UNCOMPENSATED 30 20 COMPENSATED 1 2 10 TA = - 40 TO + 125C 3 4 5 6 20 30 40 PRESSURE DIFFERENTIAL 7 8 50 Figure 7. Typical-Output Voltage versus Pressure and Temperature for Compensated and Uncompensated Devices Figure 6. Output versus Pressure Differential Freescale Semiconductor, Inc... COMPENSATED VS = 10 Vdc UNCOMPENSATED VS = 3 Vdc P1 > P2 + 25C 70 SPAN RANGE (TYP) OUTPUT (mVdc) VS = 10 Vdc TA = 25C MPX2100 P1 > P2 40 5.0 MAX TRANSFER FUNCTION: 4.5 Vout = Vs* (0.009*P - 0.04) error 4.0 Vs = 5.0 Vdc 3.5 TEMP = 0 to 85C 3.0 MPX5100D P1 > P2 2.5 TYP 2.0 1.5 1.0 MIN 0.5 0 0 10 20 30 40 50 60 70 80 90 100 110 DIFFERENTIAL PRESSURE (in kPa) Figure 8. Signal Conditioned MPX5100 3-10 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Unibody Cross-sectional Drawings SILICONE GEL DIE COAT WIRE BOND DIFFERENTIAL/GAUGE STAINLESS STEEL DIE METAL COVER P1 EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT P2 DIE BOND SILICONE GEL ABSOLUTE DIE COAT DIE P1 STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE WIRE BOND LEAD FRAME ABSOLUTE ELEMENT DIE BOND Freescale Semiconductor, Inc... Figure 9. Cross-Sectional Diagrams (not to scale) Figure 9 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from harsh environments, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term stability. Contact the factory for information regarding media compatibility in your application. STAINLESS STEEL METAL COVER DIE FLUORO SILICONE DIE COAT P1 WIRE BONDS EPOXY CASE LEAD FRAME Figure 10. Cross-Sectional Diagram (not to scale) Figure 10 illustrates the differential/gauge die in the basic chip carrier (Case 473). A silicone gel isolates the die surface and wirebonds from the environment, while Motorola Sensor Device Data allowing the pressure signal to be transmitted to the silicon diaphragm. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-11 Freescale Semiconductor, Inc. Integration +5 V ON-CHIP SIGNAL CONDITIONING Freescale Semiconductor, Inc... To make the designer's job even easier, Motorola's integrated devices carry sensor technology one step further. In addition to the on-chip temperature compensation and calibration offered currently on the 2000 series, amplifier signal conditioning has been integrated on-chip in the 4000, 5000 and 6000 series to allow interface directly to any microcomputer with an on-board A/D converter. The signal conditioning is accomplished by means of a four-stage amplification network, incorporating linear bipolar processing, thin-film metallization techniques, and interactive laser trimming to provide the state-of-the-art in sensor technology. 3 m 1.0 F 1 m OUTPUT 470 pF 0.01 F IPS 2 Recommended Power Supply Decoupling. For output filtering recommendations, please refer to Application Note AN1646. Design Considerations for Different Levels of Sensor Integration DESIGN ADVANTAGES Uncompensated Sensors DESIGN CONSIDERATIONS High Sensitivity Device-to-Device Variation in Offset and Span Lowest Device Cost Temperature Compensation Circuitry Required Low-Level Output Allows Flexibility of Signal Conditioning Requires Signal Conditioning/ Amplification of Output Signal Relatively Low Input Impedance (400 Typical) Temperature Compensated & Calibrated (2000 Series) Reduced Device-to-Device Variations in Offset and Span Lower Sensitivity Due to Span Compensation (Compared to Uncompensated) Reduced Temperature Drift in Offset and Span Priced Higher than Uncompensated Device Reasonable Input Impedance (2K Typical) Requires Signal Conditioning/ Amplification of Output Signal Low Level Output Allows Flexibility in Signal Conditioning Integrated Pressure Sensors (4000, 5000 and 6000 Series) No Amplification Needed Direct Interface to MPU Priced Higher than Compensated/ Uncompensated Device Signal Conditioning, Calibration of Span and Offset, Temperature Compensation Included On-Chip 3-12 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Sensor Applications AUTOMOTIVE/AVIATION APPLICATIONS INDUSTRIAL/COMMERCIAL APPLICATIONS * Fuel Level Indicator * Electronic Fire Fighting Control * Altimeters * Flow Control * Air Speed Indicator * Barometer * Ejection Seat Control * HVAC Systems * Turbo Boost Control * Tire Pressure Monitoring * Manifold Vacuum Control * Water Filtered Systems (Flow Rate Indicator) * Fuel Flow Metering * Air Filtered Systems (Flow Rate Indicator) * Oil Filter Flow Indicator * Tactile Sensing for Robotic Systems * Oil Pressure Sensor * Boiler Pressure Indicators Freescale Semiconductor, Inc... * Air Flow Measurement * Anti-Start * End of Tape Readers * Breathalizer Systems * Disc Drive Control/Protection Systems * Smart Suspension Systems * Ocean Wave Measurement * Variometer-Hang glider & Sailplanes * Diving Regulators * Automotive Speed Control * Oil Well Logging HEALTHCARE APPLICATIONS * Building Automation (Balancing, Load Control, Windows) * Fluid Dispensers * Blood Pressure * Explosion Sensing -- Shock Wave Monitors * Esophagus Pressure * Load Cells * Heart Monitor * Autoclave Release Control * Interoccular Pressure * Soil Compaction Monitor -- Construction * Saline Pumps * Water Depth Finders (Industrial, Sport Fishing/Diving) * Kidney Dialysis * Pneumatic Controls -- Robotics * Blood Gas Analysis * Pinch Roller Pressure -- Paper Feed * Blood Serum Analysis * Blower Failure Safety Switch -- Computer * Seating Pressure (Paraplegic) * Vacuum Cleaner Control * Respiratory Control * Intravenous Infusion Pump Control * Electronic Drum * Hospital Beds * Pressure Controls Systems -- Building, Domes * Drug Delivery * Engine Dynamometer * IUPC * Water Level Monitoring * Patient Monitors * Altimeters Motorola has tested media tolerant sensor devices in selected solutions or environments and test results are based on particular conditions and procedures selected by Motorola. Customers are advised that the results may vary for actual services conditions. Customers are cautioned that they are responsible to determine the media compatibility of sensor devices in their applications and the foreseeable use and misuses of their applications. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-13 Freescale Semiconductor, Inc. Pressure Sensor FAQ's We have discovered that many of our customers have similar questions about certain aspects of our pressure sensor technology and operation. Here are the most frequently asked questions and answers that have been explained in relatively non-technical terms. Freescale Semiconductor, Inc... Q. How do I calculate total pressure error for my applications? A. You can calculate total error in two fashions, worst case error and most probable error. Worst case error is taking all the individual errors and adding them up, while most probable error sums the squares of the individual errors and then take the square root of the total. In summary, Error (Worst Case) = E1 + E2 + E3 + ... + En, while Error (Most Probable) = SQRT[(E1)2 + (E2)2 + (E3)2 + ... (En)2]; Please note that not all errors may apply in your individual application. Q. What is the media tolerance of our pressure sensors? A. Most Motorola pressure sensors are specifically designed for dry air applications. However, Motorola now offers an MPXAZ series specifically designed for improved media resistance. This series incorporates a durable barrier that allows the sensor to operate reliably in high humidity conditions as well as environments containing common automotive media. NOTE: Applications exposing the sensor to media other than what has been specified could potentially limit the lifetime of the sensor. Please consult the Motorola factory for more information regarding media compatibility in your specific application. Q. Can I pull a vacuum on P1? A. Motorola pressure sensors are designed to measure pressure in one direction and are not bi-directional. It is 3-14 possible to measure either a positive pressure OR a negative pressure, but not both. For example, the sensor can be designed to accept a "positive" pressure on the P1 port, providing that P1 is greater or equal to P2 while staying with in the sensors specified pressure range. Or, the sensor can measure "negative" pressure (a vacuum)by applying the pressure to the P2 port, again while P1 is greater or equal to P2 and staying within the sensors specified range. Our pressure sensors are based on a silicon diaphragm and can not tolerate a pressure that alternates from positive to negative without resulting damage. The devices are rated for over pressure and burst but should not be intentionally designed to operate in a bi-directional manner. If you need to measure both a positive and negative pressure within the same system, we suggest designing with two separate sensors, one for each pressure type. Or, a mechanical pressure transducer should be utilized. Q. What will happen if I run the pressure sensor beyond the rated operating pressure? A. For bare elements (uncompensated and compensated series devices), when you take the sensor higher than the rated pressure, the part will still provide an output increasing linearly with pressure. When you go below the minimum rated pressure, the output of the sensor will eventually go negative. Motorola, however, does not guarantee electrical specifications beyond the rated operating pressure range specified in the data sheet of each device. The integrated series devices will not function at all beyond the rated pressure of the part. These series of parts will saturate at near 4.8 V and 0.2 V and thus no further change in output will occur. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 10 kPa Uncompensated Silicon Pressure Sensors The MPX10 and MPXV10GC series devices are silicon piezoresistive pressure sensors providing a very accurate and linear voltage output -- directly proportional to the applied pressure. These standard, low cost, uncompensated sensors permit manufacturers to design and add their own external temperature compensation and signal conditioning networks. Compensation techniques are simplified because of the predictability of Motorola's single element strain gauge design. Figure 1 shows a schematic of the internal circuitry on the stand-alone pressure sensor chip. MPX10 MPXV10GC SERIES 0 to 10 kPa (0 - 1.45 psi) 35 mV FULL SCALE SPAN (TYPICAL) Features * Low Cost SMALL OUTLINE PACKAGE UNIBODY PACKAGE Freescale Semiconductor, Inc... * Patented Silicon Shear Stress Strain Gauge Design * Ratiometric to Supply Voltage * Easy to Use Chip Carrier Package Options * Differential and Gauge Options * Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package MPXV10GC6U CASE 482A Application Examples MPX10D CASE 344 * Air Movement Control * Environmental Control Systems * Level Indicators * Leak Detection * Medical Instrumentation * Industrial Controls * Pneumatic Control Systems MPXV10GC7U CASE 482C * Robotics 3 PIN NUMBER + VS 2 + Vout SENSING ELEMENT 4 - Vout 1 1 Gnd 5 N/C 2 +Vout Vs 6 N/C 3 7 N/C 4 -Vout 8 N/C NOTE: Pin 1 is noted by the notch in the lead. GND MPX10DP CASE 344C PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. Figure 1. Uncompensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). REV 10 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-15 MPX10 MPXV10GC SERIESFreescale Semiconductor, Inc. MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax Pburst Tstg 75 kPa 100 kPa - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Burst Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 3.0 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Differential Pressure Range(1) Supply Voltage(2) Freescale Semiconductor, Inc... Supply Current Full Scale Span(3) Offset(4) Sensitivity Linearity(5) Symbol Min POP VS 0 -- Typ Max Unit -- 10 kPa 3.0 6.0 Vdc Io VFSS Voff -- 6.0 -- mAdc 20 35 50 mV 0 20 35 mV V/P -- 3.5 -- mV/kPa %VFSS %VFSS -- -1.0 -- 1.0 Pressure Hysteresis(5) (0 to 10 kPa) Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.1 -- -- -- 0.5 -- Temperature Coefficient of Full Scale Span(5) Temperature Coefficient of Offset(5) TCVFSS TCVoff - 0.22 -- - 0.16 -- 15 -- Temperature Coefficient of Resistance(5) TCR 0.28 -- 0.34 Input Impedance Zin Zout 400 -- 550 750 -- 1250 tR -- -- 1.0 -- ms -- 20 -- ms -- -- 0.5 -- %VFSS Output Impedance Response Time(6) (10% to 90%) Warm-Up Time(7) Offset Stability(8) %VFSS %VFSS/C V/C %Zin/C NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * TCR: Zin deviation with minimum rated pressure applied, over the temperature range of - 40C to +125C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-16 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX10 MPXV10GC SERIES tion over both - 40 to +125C and 0 to + 80C ranges are presented in Motorola Applications Note AN840. TEMPERATURE COMPENSATION Figure 2 shows the typical output characteristics of the MPX10 and MPXV10GC series over temperature. Because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. However, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. Temperature compensation and offset calibration can be achieved rather simply with additional resistive components, or by designing your system using the MPX2010D series sensor. Several approaches to external temperature compensa- LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range (Figure 3). There are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. 70 70 60 - 40C 50 SPAN RANGE (TYP) + 125C 40 30 20 OFFSET (TYP) 10 0 PSI 0 kPa 0.3 2.0 0.6 0.9 1.2 4.0 6.0 8.0 PRESSURE DIFFERENTIAL 1.5 50 ACTUAL 40 SPAN (VFSS) 30 THEORETICAL 20 10 OFFSET (VOFF) MAX POP 0 0 10 PRESSURE (kPA) Figure 2. Output versus Pressure Differential SILICONE DIE COAT Figure 3. Linearity Specification Comparison STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 WIRE BOND LINEARITY 60 + 25C VS = 3 Vdc P1 > P2 OUTPUT (mVdc) OUTPUT (mVdc) Freescale Semiconductor, Inc... 80 LEAD FRAME P2 RTV DIE BOND Figure 4. Unibody Package -- Cross-Sectional Diagram (not to scale) Figure 4 illustrates the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX10 and MPXV10GC series pressure sensor oper- Motorola Sensor Device Data ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-17 MPX10 MPXV10GC SERIESFreescale Semiconductor, Inc. PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola pres- Freescale Semiconductor, Inc... Part Number sure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPX10D 344 Stainless Steel Cap MPX10DP 344C Side with Part Marking MPX10GP 344B Side with Port Attached MPX10GS 344E Side with Port Attached MPXV10GC6U 482A Side with Part Marking MPXV10GC7U 482C Side with Part Marking ORDERING INFORMATION -- UNIBODY PACKAGE MPX10 series pressure sensors are available in differential and gauge configurations. Devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Differential Case 344 MPX10D MPX10D Ported Elements Differential Case 344C MPX10DP MPX10DP Gauge Case 344B MPX10GP MPX10GP Gauge Case 344E MPX10GS MPX10D ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV10GC SERIES) No Device Type/Order No. Packing Options Case Type Device Marking MPXV10GC6U Rails Case 482A MPXV10G MPXV10GC6T1 Tape and Reel Case 482A MPXV10G MPXV10GC7U Rails Case 482C MPXV10G 3-18 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 10 kPa Uncompensated Silicon Pressure Sensors The MPX12 series device is a silicon piezoresistive pressure sensor providing a very accurate and linear voltage output -- directly proportional to the applied pressure. This standard, low cost, uncompensated sensor permits manufacturers to design and add their own external temperature compensating and signal conditioning networks. Compensation techniques are simplified because of the predictability of Motorola's single element strain gauge design. Features * Low Cost MPX12 SERIES 0 to 10 kPa (0 - 1.45 psi) 55 mV FULL SCALE SPAN (TYPICAL) * Patented Silicon Shear Stress Strain Gauge Design Freescale Semiconductor, Inc... * Ratiometric to Supply Voltage * Easy to Use Chip Carrier Package Options * Differential and Gauge Options * Durable Epoxy Package Application Examples * Air Movement Control MPX12D CASE 344 * Environmental Control Systems * Level Indicators * Leak Detection * Medical Instrumentation * Industrial Controls * Pneumatic Control Systems * Robotics Figure 1 shows a schematic of the internal circuitry on the stand-alone pressure sensor chip. PIN 3 + VS MPX12DP CASE 344C PIN 2 + Vout SENSING ELEMENT PIN 4 - Vout PIN 1 Figure 1. Uncompensated Pressure Sensor Schematic PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-19 Freescale Semiconductor, Inc. MPX12 SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax Pburst Tstg 75 kPa 100 kPa - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Burst Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 3.0 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Differential Pressure Range(1) Supply Voltage(2) Freescale Semiconductor, Inc... Supply Current Full Scale Span(3) Offset(4) Sensitivity Linearity(5) Symbol Min POP VS 0 -- Typ Max Unit -- 10 kPa 3.0 6.0 Vdc Io VFSS Voff -- 6.0 -- mAdc 45 55 70 mV 0 20 35 mV V/P -- 5.5 -- mV/kPa %VFSS %VFSS -- -0.5 -- 5.0 Pressure Hysteresis(5) (0 to 10 kPa) Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.1 -- -- -- 0.5 -- Temperature Coefficient of Full Scale Span(5) Temperature Coefficient of Offset(5) TCVFSS TCVoff - 0.22 -- - 0.16 %VFSS %VFSS/C -- 15 -- V/C Temperature Coefficient of Resistance(5) TCR 0.28 -- 0.34 Input Impedance Zin Zout 400 -- 550 %Zin/C 750 -- 1250 tR -- -- 1.0 -- ms -- 20 -- ms -- -- 0.5 -- %VFSS Output Impedance Response Time(6) (10% to 90%) Warm-Up Time(7) Offset Stability(8) NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * TCR: Zin deviation with minimum rated pressure applied, over the temperature range of - 40C to +125C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-20 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. tion over both - 40 to +125C and 0 to + 80C ranges are presented in Motorola Applications Note AN840. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range (Figure 3). There are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. 80 70 70 - 40C 50 SPAN RANGE (TYP) + 125C 40 30 20 OFFSET (TYP) 10 0 PSI 0 kPa 0.3 2.0 0.6 0.9 1.2 4.0 6.0 8.0 PRESSURE DIFFERENTIAL 1.5 50 ACTUAL 40 SPAN (VFSS) 30 THEORETICAL 20 10 OFFSET (VOFF) 0 0 10 MAX POP PRESSURE (kPA) Figure 2. Output versus Pressure Differential SILICONE DIE COAT Figure 3. Linearity Specification Comparison EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 WIRE BOND LINEARITY 60 + 25C VS = 3 Vdc P1 > P2 OUTPUT (mVdc) OUTPUT (mVdc) Freescale Semiconductor, Inc... TEMPERATURE COMPENSATION Figure 2 shows the typical output characteristics of the MPX12 series over temperature. Because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. However, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. Temperature compensation and offset calibration can be achieved rather simply with additional resistive components, or by designing your system using the MPX2010D series sensor. Several approaches to external temperature compensa- 60 MPX12 SERIES LEAD FRAME P2 STAINLESS STEEL METAL COVER EPOXY CASE RTV DIE BOND Figure 4. Cross-Sectional Diagram (not to scale) Figure 4 illustrates the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX12 series pressure sensor operating characteris- Motorola Sensor Device Data tics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-21 Freescale Semiconductor, Inc. MPX12 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPX12D 344 Stainless Steel Cap MPX12DP 344C Side with Part Marking MPX12GP 344B Side with Port Attached Freescale Semiconductor, Inc... ORDERING INFORMATION MPX12 series pressure sensors are available in differential and gauge configurations. Devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Differential Case 344 MPX12D MPX12D Ported Elements Differential Case 344C MPX12DP MPX12DP Gauge Case 344B MPX12GP MPX12GP 3-22 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 10 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors UNIBODY PACKAGE Freescale Semiconductor, Inc... The MPX2010/MPXV2010G series silicon piezoresistive pressure sensors provide a very ac c ur at e and l i n e a r v o l ta g e o u tp u t -- d i r ec tl y proportional to the applied pressure. These sensors house a single monolithic silicon die with the strain gauge and thin-film resistor network integrated on each chip. The sensor is laser trimmed for precise span, offset calibration and temperature compensation. MPX2010 MPXV2010G SERIES Motorola Preferred Device COMPENSATED PRESSURE SENSOR 0 to 10 kPa (0 to 1.45 psi) FULL SCALE SPAN: 25 mV MPX2010D CASE 344 Features SMALL OUTLINE PACKAGE SURFACE MOUNT * Temperature Compensated over 0C to + 85C * Ratiometric to Supply Voltage * Differential and Gauge Options Application Examples * Respiratory Diagnostics * Air Movement Control MPX2010GP CASE 344B * Controllers MPXV2010GP CASE 1369 * Pressure Switching Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 MPX2010DP CASE 344C Vout+ MPXV2010DP CASE 1351 Vout- PIN NUMBER 1 GND MPX2010GS CASE 344E Figure 1. Temperature Compensated and Calibrated Pressure Sensor Schematic 1 Gnd 5 N/C 2 6 N/C 3 +Vout VS 7 N/C 4 -Vout 8 N/C NOTE: Pin 1 is noted by the notch in the lead. VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). MPX2010GSX CASE 344F PIN NUMBER Preferred devices are Motorola recommended choices for future use and best overall value. REV 9 Motorola Sensor Device Data 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-23 Freescale Semiconductor, Inc. MPX2010 MPXV2010G SERIES MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 75 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 10 kPa Supply Voltage(2) VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 24 25 26 mV Voff -1.0 -- 1.0 mV Sensitivity V/P -- 2.5 -- mV/kPa Linearity(5) -- -1.0 -- 1.0 %VFSS Pressure Hysteresis(5) (0 to 10 kPa) -- -- 0.1 -- %VFSS Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance -- -- 0.5 -- %VFSS TCVFSS -1.0 -- 1.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2550 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-24 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX2010 Inc. MPXV2010G SERIES ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION VS = 10 Vdc TA = 25C P1 > P2 OUTPUT (mVdc) 30 25 20 aMAX 15 TYP SPAN RANGE (TYP) 10 MIN 5 0 -5 kPa PSI 2.5 0.362 5 0.725 7.5 1.09 10 1.45 OFFSET (TYP) Freescale Semiconductor, Inc... Figure 2. Output versus Pressure Differential This performance over temperature is achieved by having both the shear stress strain gauge and the thin-film resistor circuitry on the same silicon diaphragm. Each chip is dynamically laser trimmed for precise span and offset calibration and temperature compensation. Figure 2 shows the output characteristics of the MPX2010/MPXV2010G series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. The effects of temperature on full scale span and offset are very small and are shown under Operating Characteristics. SILICONE DIE COAT STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 EPOXY CASE WIRE BOND LEAD FRAME P2 RTV DIE BOND Figure 3. Unibody Package -- Cross-Sectional Diagram (not to scale) Figure 3 illustrates the differential/gauge die in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2010/MPXV2010G series pressure sensor oper- Motorola Sensor Device Data ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-25 Freescale Semiconductor, Inc. MPX2010 MPXV2010G SERIES LEAST SQUARE DEVIATION LEAST SQUARES FIT EXAGGERATED PERFORMANCE CURVE RELATIVE VOLTAGE OUTPUT LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 5) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) Freescale Semiconductor, Inc... 0 100 Figure 4. Linearity Specification Comparison PRESSURE (P1) / VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPX2010D 344 Stainless Steel Cap MPX2010DP 344C Side with Part Marking MPX2010GP 344B Side with Port Attached MPX2010GS 344E Side with Port Attached MPX2010GSX 344F Side with Port Attached MPXV2010GP 1369 Side with Port Attached MPXV2010DP 1351 Side with Part Marking ORDERING INFORMATION -- UNIBODY PACKAGE (MPX2010 SERIES) MPX Series Device Type Options Order Number Case Type Device Marking Basic Element Differential 344 MPX2010D MPX2010D Ported Elements Differential, Dual Port 344C MPX2010DP MPX2010DP Gauge 344B MPX2010GP MPX2010GP Gauge, Axial 344E MPX2010GS MPX2010D Gauge, Axial PC Mount 344F MPX2010GSX MPX2010D ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV2010G SERIES) Device Type Ported Elements 3-26 Options Case No. MPX Series Order No. Packing Options Marking Gauge, Side Port, SMT 1369 MPXV2010GP Trays MPXV2010G Differential, Dual Port, SMT 1351 MPXV2010DP Trays MPXV2010G For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 50 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors The MPX2050 series device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. MPX2050 SERIES 0 to 50 kPa (0 to 7.25 psi) 40 mV FULL SCALE SPAN (TYPICAL) Features Freescale Semiconductor, Inc... * Temperature Compensated Over 0C to + 85C * Unique Silicon Shear Stress Strain Gauge * Easy to Use Chip Carrier Package Options * Ratiometric to Supply Voltage * Differential and Gauge Options MPX2050D CASE 344 * 0.25% Linearity (MPX2050) Application Examples * Pump/Motor Controllers * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching * Non-Invasive Blood Pressure Measurement MPX2050GP CASE 344B Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 Vout+ Vout- MPX2050DP CASE 344C 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). MPX2050GSX CASE 344F PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. REV 8 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-27 Freescale Semiconductor, Inc. MPX2050 SERIES MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 50 kPa Supply Voltage(2) VS -- 10 16 Vdc Characteristic Freescale Semiconductor, Inc... Supply Current Io -- 6.0 -- mAdc Full Scale Span(3) MPX2050 VFSS 38.5 40 41.5 mV Offset(4) MPX2050 Voff -1.0 -- 1.0 mV V/P -- 0.8 -- mV/kPa -- - 0.25 -- 0.25 %VFSS -- -- 0.1 -- %VFSS Sensitivity Linearity(5) MPX2050 Pressure Hysteresis(5) (0 to 50 kPa) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance -- -- 0.5 -- %VFSS TCVFSS -1.0 -- 1.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-28 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LEAST SQUARES FIT EXAGGERATED PERFORMANCE CURVE RELATIVE VOLTAGE OUTPUT LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. MPX2050 SERIES LEAST SQUARE DEVIATION STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION Figure 3 shows the minimum, maximum and typical output characteristics of the MPX2050 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. VS = 10 Vdc TA = 25C MPX2050 P1 > P2 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 30 25 20 TYP SPAN RANGE (TYP) MAX 10 STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 OFFSET (TYP) Figure 3. Output versus Pressure Differential Figure 4 illustrates the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2050 series pressure sensor operating charac- Motorola Sensor Device Data EPOXY CASE WIRE BOND MIN 5 kPa PSI SILICONE DIE COAT P1 15 0 -5 The effects of temperature on Full-Scale Span and Offset are very small and are shown under Operating Characteristics. LEAD FRAME P2 RTV DIE BOND Figure 4. Cross-Sectional Diagram (not to scale) teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-29 Freescale Semiconductor, Inc. MPX2050 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die. The Motorola MPX pressure sensor is Part Number designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPX2050D 344 Stainless Steel Cap MPX2050DP 344C Side with Part Marking MPX2050GP 344B Side with Port Attached MPX2050GSX 344F Side with Port Attached Freescale Semiconductor, Inc... ORDERING INFORMATION MPX2050 series pressure sensors are available in differential and gauge configurations. Devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Differential 344 MPX2050D MPX2050D Ported Elements Differential, Dual Port 344C MPX2050DP MPX2050DP Gauge 344B MPX2050GP MPX2050GP Gauge Axial PC Mount 344F MPX2050GSX MPX2050D 3-30 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 50 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors The MPX2053/MPXV2053G device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Features * Temperature Compensated Over 0C to + 85C UNIBODY PACKAGE MPX2053 MPXV2053G SERIES Motorola Preferred Device 0 to 50 kPa (0 to 7.25 psi) 40 mV FULL SCALE SPAN (TYPICAL) Freescale Semiconductor, Inc... * Easy-to-Use Chip Carrier Package Options * Ratiometric to Supply Voltage SMALL OUTLINE PACKAGE SURFACE MOUNT * Differential and Gauge Options Application Examples * Pump/Motor Controllers MPX2053D CASE 344 * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching MPXV2053GP CASE 1369 * Non-Invasive Blood Pressure Measurement Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 MPX2053GP CASE 344B THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 Vout+ MPXV2053DP CASE 1351 Vout- PIN NUMBER 1 MPX2053DP CASE 344C GND Figure 1. Temperature Compensated Pressure Sensor Schematic Replaces MPX2050/D REV 3 Motorola Sensor Device Data Gnd 5 N/C 2 6 N/C 3 +Vout VS 7 N/C 4 -Vout 8 N/C NOTE: Pin 1 is noted by the notch in the lead. VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). Preferred devices are Motorola recommended choices for future use and best overall value. 1 MPX2053GSX CASE 344F PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout MPX2053GVP CASE 344D NOTE: Pin 1 is noted by the notch in the lead. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-31 Freescale Semiconductor, Inc. MPX2053 MPXV2053G SERIES MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 50 kPa Supply Voltage(2) VS -- 10 16 Vdc Characteristic Supply Current Io -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 -- 1.0 mV Sensitivity V/P -- 0.8 -- mV/kPa Linearity(5) -- - 0.6 -- 0.4 %VFSS Pressure Hysteresis(5) (0 to 50 kPa) -- -- 0.1 -- %VFSS Freescale Semiconductor, Inc... Full Scale Span(3) Offset(4) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance -- -- 0.5 -- %VFSS TCVFSS -2.0 -- 2.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-32 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX2053 Inc. MPXV2053G SERIES LEAST SQUARE DEVIATION LEAST SQUARES FIT EXAGGERATED PERFORMANCE CURVE RELATIVE VOLTAGE OUTPUT LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION Figure 3 shows the minimum, maximum and typical output characteristics of the MPX2053/MPXV2053G series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. VS = 10 Vdc TA = 25C MPX2053 P1 > P2 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 30 25 20 TYP SPAN RANGE (TYP) MAX 10 STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 OFFSET (TYP) Figure 3. Output versus Pressure Differential Figure 4 illustrates the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2053/MPXV2053G series pressure sensor oper- Motorola Sensor Device Data EPOXY CASE WIRE BOND MIN 5 kPa PSI SILICONE DIE COAT P1 15 0 -5 The effects of temperature on Full-Scale Span and Offset are very small and are shown under Operating Characteristics. LEAD FRAME P2 RTV DIE BOND Figure 4. Cross-Sectional Diagram (not to scale) ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-33 Freescale Semiconductor, Inc. MPX2053 MPXV2053G SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die. The Motorola MPX pressure sensor is Freescale Semiconductor, Inc... Part Number designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPX2053D 344C Stainless Steel Cap MPX2053DP 344C Side with Part Marking MPX2053GP 344B Side with Port Attached MPX2053GSX 344F Side with Port Attached MPX2053GVP 344D Stainless Steel Cap MPXV2053GP 1369 Side with Port Attached MPXV2053DP 1351 Side with Part Marking ORDERING INFORMATION -- UNIBODY PACKAGE (MPX2053 SERIES) MPX Series Device Type Options Order Number Case Type Device Marking Basic Element Differential 344 MPX2053D MPX2053D Ported Elements Differential, Dual Port 344C MPX2053DP MPX2053DP Gauge 344B MPX2053GP MPX2053GP Gauge, Axial PC Mount 344F MPX2053GSX MPX2053D Gauge, Vacuum 344D MPX2053GVP MPX2053GVP ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV2053G SERIES) Device Type Ported Elements 3-34 Options Case No. MPX Series Order No. Packing Options Marking Gauge, Side Port, SMT 1369 MPXV2053GP Trays MPXV2053G Differential, Dual Port, SMT 1351 MPXV2053DP Trays MPXV2053G For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Freescale Semiconductor, Inc... 100 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors The MPX2100 series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Features * Temperature Compensated Over 0C to + 85C * Easy-to-Use Chip Carrier Package Options * Available in Absolute, Differential and Gauge Configurations * Ratiometric to Supply Voltage * 0.25% Linearity (MPX2100D) Application Examples * Pump/Motor Controllers * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters MPX2100 SERIES 0 to 100 kPa (0 to 14.5 psi) 40 mV FULL SCALE SPAN (TYPICAL) UNIBODY PACKAGE MPX2100A/D CASE 344 Figure 1 illustrates a block diagram of the internal circuitry on the stand-alone pressure sensor chip. MPX2100AP/GP CASE 344B VS 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 Vout+ Vout- MPX2100DP CASE 344C 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The absolute sensor has a built-in reference vacuum. The output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (P1) side. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (P1) side relative to the vacuum (P2) side. Similarly, output voltage increases as increasing vacuum is applied to the vacuum (P2) side relative to the pressure (P1) side. MPX2100ASX/GSX CASE 344F PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. REV 9 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-35 Freescale Semiconductor, Inc. MPX2100 SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 100 kPa Supply Voltage(2) VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 - 2.0 -- -- 1.0 2.0 mV V/P -- 0.4 -- mV/kPa -- -- - 0.25 - 1.0 -- -- 0.25 1.0 %VFSS -- -- 0.1 -- %VFSS Freescale Semiconductor, Inc... Characteristic Full Scale Span(3) MPX2100A, MPX2100D Offset(4) MPX2100D MPX2100A Series Sensitivity Linearity(5) MPX2100D Series MPX2100A Series Pressure Hysteresis(5) (0 to 100 kPa) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) -- -- 0.5 -- %VFSS TCVFSS -1.0 -- 1.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Input Impedance Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-36 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. MPX2100 SERIES LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE LEAST SQUARE DEVIATION STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION The effects of temperature on Full Scale Span and Offset are very small and are shown under Operating Characteristics. Figure 3 shows the output characteristics of the MPX2100 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. 40 VS = 10 Vdc TA = 25C P1 > P2 35 30 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 25 20 TYP SPAN RANGE (TYP) MAX 15 10 MIN 5 kPa PSI 0 -5 0 25 3.62 50 7.25 75 10.87 100 14.5 OFFSET (TYP) Figure 3. Output versus Pressure Differential SILICONE GEL DIE COAT WIRE BOND DIFFERENTIAL/GAUGE STAINLESS STEEL DIE METAL COVER P1 EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT P2 DIE BOND SILICONE GEL ABSOLUTE DIE COAT DIE P1 STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE WIRE BOND LEAD FRAME ABSOLUTE ELEMENT P2 DIE BOND Figure 4. Cross-Sectional Diagrams (Not to Scale) Figure 4 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2100 series pressure sensor operating charac- Motorola Sensor Device Data teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-37 Freescale Semiconductor, Inc. MPX2100 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die. The differential or gauge sensor is designed to operate with positive differential pressure applied, P1 > P2. The absolute sensor is designed for vacuum applied to P1 side. The Pressure (P1) side may be identified by using the table below: Part Number MPX2100A Case Type MPX2100D Freescale Semiconductor, Inc... MPX2100DP Pressure (P1) Side Identifier 344 Stainless Steel Cap 344C Side with Part Marking MPX2100AP MPX2100GP 344B Side with Port Attached MPX2100ASX MPX2100GSX 344F Side with Port Attached ORDERING INFORMATION MPX2100 series pressure sensors are available in absolute, differential and gauge configurations. Devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Absolute, Differential 344 MPX2100A MPX2100D MPX2100A MPX2100D Ported Elements Differential, Dual Port 344C MPX2100DP MPX2100DP Absolute, Gauge 344B MPX2100AP MPX2100GP MPX2100AP MPX2100GP Absolute, Gauge Axial 344F MPX2100ASX MPX2100GSX MPX2100A MPX2100D 3-38 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Freescale Semiconductor, Inc... 100 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors The MPX2102/MPXV2102G series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Features * Temperature Compensated Over 0C to + 85C UNIBODY PACKAGE * Easy-to-Use Chip Carrier Package Options * Available in Absolute, Differential and Gauge Configurations * Ratiometric to Supply Voltage Application Examples * Pump/Motor Controllers MPX2102A/D * Robotics CASE 344 * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters MPX2102 MPXV2102G SERIES Motorola Preferred Device 0 to 100 kPa (0 to 14.5 psi) 40 mV FULL SCALE SPAN (TYPICAL) SMALL OUTLINE PACKAGE SURFACE MOUNT MPXV2102GP CASE 1369 Figure 1 illustrates a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT MPX2102AP/GP CASE 344B 2 4 Vout+ MPXV2102DP CASE 1351 Vout- 1 PIN NUMBER GND Figure 1. Temperature Compensated Pressure Sensor Schematic MPX2102DP CASE 344C VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The absolute sensor has a built-in reference vacuum. The output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (P1) side. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (P1) side relative to the vacuum (P2) side. Similarly, output voltage increases as increasing vacuum is applied to the vacuum (P2) side relative to the pressure (P1) side. Preferred devices are Motorola recommended choices for future use and best overall value. REV 2 Motorola Sensor Device Data 1 Gnd 5 N/C 2 +Vout VS 6 N/C 3 7 N/C 4 -Vout 8 N/C NOTE: Pin 1 is noted by the notch in the lead. MPX2102ASX/GSX CASE 344F PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout MPX2102GVP CASE 344D NOTE: Pin 1 is noted by the notch in the lead. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-39 Freescale Semiconductor, Inc. MPX2102 MPXV2102G SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 100 kPa Supply Voltage(2) VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 - 2.0 -- -- 1.0 2.0 mV V/P -- 0.4 -- mV/kPa -- -- - 0.6 - 1.0 -- -- 0.4 1.0 %VFSS -- -- 0.1 -- %VFSS Characteristic Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) MPX2102D Series MPX2102A Series Sensitivity Linearity(5) MPX2102D Series MPX2102A Series Pressure Hysteresis(5) (0 to 100 kPa) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) -- -- 0.5 -- %VFSS TCVFSS -2.0 -- 2.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Input Impedance Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-40 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX2102 Inc. MPXV2102G SERIES LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. LEAST SQUARE DEVIATION LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION The effects of temperature on Full Scale Span and Offset are very small and are shown under Operating Characteristics. Figure 3 shows the output characteristics of the MPX2102/MPXV2102G series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. 40 VS = 10 Vdc TA = 25C P1 > P2 35 30 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 25 20 TYP SPAN RANGE (TYP) MAX 15 10 MIN 5 kPa PSI 0 -5 0 25 3.62 50 7.25 75 10.87 100 14.5 OFFSET (TYP) Figure 3. Output versus Pressure Differential SILICONE GEL DIE COAT WIRE BOND DIFFERENTIAL/GAUGE STAINLESS STEEL DIE METAL COVER P1 EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT P2 DIE BOND SILICONE GEL ABSOLUTE DIE COAT DIE P1 EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE WIRE BOND LEAD FRAME ABSOLUTE ELEMENT P2 STAINLESS STEEL METAL COVER EPOXY CASE DIE BOND Figure 4. Cross-Sectional Diagrams (Not to Scale) Figure 4 illustrates the absolute sensing configuration (right) and the differential or gauge configuration in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. Motorola Sensor Device Data The MPX2102/MPXV2102G series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-41 Freescale Semiconductor, Inc. MPX2102 MPXV2102G SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die. The differential or gauge sensor is designed to operate with positive differential pressure Part Number MPX2102A Case Type MPX2102D Pressure (P1) Side Identifier 344 Stainless Steel Cap 344C Side with Part Marking 344B Side with Port Attached 344D Stainless Steel Cap 344F Side with Port Attached MPXV2102GP 1369 Side with Port Attached MPXV2102DP 1351 Side with Part Marking MPX2102DP MPX2102AP MPX2102GP MPX2102GVP MPX2102ASX Freescale Semiconductor, Inc... applied, P1 > P2. The absolute sensor is designed for vacuum applied to P1 side. The Pressure (P1) side may be identified by using the table below: MPX2102GSX ORDERING INFORMATION -- UNIBODY PACKAGE (MPX2102 SERIES) MPX Series Device Type Options Order Number Case Type Device Marking Basic Element Absolute, Differential 344 MPX2102A MPX2102D MPX2102A MPX2102D Ported Elements Differential, Dual Port 344C MPX2102DP MPX2102DP Absolute, Gauge 344B MPX2102AP MPX2102GP MPX2102AP MPX2102GP Absolute, Gauge Axial 344F MPX2102ASX MPX2102GSX MPX2102A MPX2102D Gauge, Vacuum 344D MPX2102GVP MPX2102GVP ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV2102G SERIES) Device Type Ported Elements 3-42 Options Case No. MPX Series Order No. Packing Options Marking Gauge, Side Port, SMT 1369 MPXV2102GP Trays MPXV2102G Differential, Dual Port, SMT 1351 MPXV2102DP Trays MPXV2102G For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Freescale Semiconductor, Inc... 200 kPa On-Chip Temperature Compensated & Calibrated Pressure Sensors The MPX2200 series device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. They are designed for use in applications such as pump/motor controllers, robotics, level indicators, medical diagnostics, pressure switching, barometers, altimeters, etc. Features * Temperature Compensated Over 0C to + 85C * 0.25% Linearity (MPX2200D) * Easy-to-Use Chip Carrier Package Options * Available in Absolute, Differential and Gauge Configurations Application Examples * Pump/Motor Controllers * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters MPX2200 SERIES 0 to 200 kPa (0 to 29 psi) 40 mV FULL SCALE SPAN (TYPICAL) UNIBODY PACKAGE MPX2200A/D CASE 344 Figure 1 illustrates a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 MPX2200AP/GP CASE 344B THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 Vout+ Vout- 1 MPX2200DP CASE 344C GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The absolute sensor has a built-in reference vacuum. The output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (P1) side. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (P1) side relative to the vacuum (P2) side. Similarly, output voltage increases as increasing vacuum is applied to the vacuum (P2) side relative to the pressure (P1) side. MPX2200GVP CASE 344D PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout NOTE: Pin 1 is noted by the notch in the lead. REV 9 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-43 Freescale Semiconductor, Inc. MPX2200 SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 800 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit 0 -- 200 kPa Supply Voltage POP VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS Voff 38.5 40 41.5 mV -1.0 -- 1.0 mV V/P -- 0.2 -- mV/kPa -- - 0.25 - 1.0 -- -- 0.25 1.0 %VFSS -- -- 0.1 -- %VFSS %VFSS Characteristics Pressure Range(1) Freescale Semiconductor, Inc... Full Scale Span(3) Offset(4) Sensitivity Linearity(5) MPX2200D Series MPX2200A Series Pressure Hysteresis(5) (0 to 200 kPa) Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.5 -- TCVFSS TCVoff -1.0 -- 1.0 -1.0 -- 1.0 %VFSS mV Zin Zout 1300 -- 2500 1400 -- 3000 -- 1.0 -- ms Warm-Up tR -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance Output Impedance Response Time(6) (10% to 90%) NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-44 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. MPX2200 SERIES LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE LEAST SQUARE DEVIATION STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION The effects of temperature on Full Scale Span and Offset are very small and are shown under Operating Characteristics. Figure 3 shows the output characteristics of the MPX2200 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. VS = 10 Vdc TA = 25C P1 > P2 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 TYP 30 25 SPAN RANGE (TYP) MAX 20 15 10 MIN 5 0 -5 kPa 0 PSI 25 50 7.25 75 100 14.5 150 21.75 125 175 200 29 OFFSET PRESSURE Figure 3. Output versus Pressure Differential SILICONE GEL DIE COAT DIFFERENTIAL/GAUGE STAINLESS STEEL DIE METAL COVER P1 EPOXY CASE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE WIRE BOND LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT P2 DIE BOND SILICONE GEL ABSOLUTE DIE COAT DIE P1 STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE WIRE BOND LEAD FRAME ABSOLUTE ELEMENT P2 DIE BOND Figure 4. Cross-Sectional Diagrams (Not to Scale) Figure 4 illustrates an absolute sensing die (right) and the differential or gauge die in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2200 series pressure sensor operating charac- Motorola Sensor Device Data teristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-45 Freescale Semiconductor, Inc. MPX2200 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die from the environment. The differential or gauge sensor is designed to operate with positive differenPart Number MPX2200A Case Type MPX2200D MPX2200DP MPX2200AP MPX2200GP MPX2200GVP Freescale Semiconductor, Inc... tial pressure applied, P1 > P2. The absolute sensor is designed for vacuum applied to P1 side. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier 344 Stainless Steel Cap 344C Side with Part Marking 344B Side with Port Attached 344D Stainless Steel Cap ORDERING INFORMATION MPX2200 series pressure sensors are available in absolute, differential and gauge configurations. Devices are available in the basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Absolute, Differential 344 MPX2200A MPX2200D MPX2200A MPX2200D Ported Elements Differential 344C MPX2200DP MPX2200DP Absolute, Gauge 344B MPX2200AP MPX2200GP MPX2200AP MPX2200GP Gauge, Vacuum 344D MPX2200GVP MPX2200GVP 3-46 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Freescale Semiconductor, Inc... 200 kPa On-Chip Temperature Compensated & Calibrated Pressure Sensors MPX2202 MPXV2202G SERIES The MPX2202/MPXV2202G device series is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. They are designed for use in applications such as pump/motor controllers, robotics, level indicators, medical diagnostics, pressure switching, barometers, altimeters, etc. Features UNIBODY PACKAGE * Temperature Compensated Over 0C to + 85C * Easy-to-Use Chip Carrier Package Options * Available in Absolute, Differential and Gauge Configurations Application Examples * Pump/Motor Controllers * Robotics MPX2202A/D CASE 344 * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters Motorola Preferred Device 0 to 200 kPa (0 to 29 psi) 40 mV FULL SCALE SPAN (TYPICAL) SMALL OUTLINE PACKAGE SURFACE MOUNT MPXV2202GP CASE 1369 Figure 1 illustrates a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 MPX2202AP/GP CASE 344B Vout+ MPXV2202DP CASE 1351 Vout- PIN NUMBER 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The absolute sensor has a built-in reference vacuum. The output voltage will decrease as vacuum, relative to ambient, is drawn on the pressure (P1) side. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure (P1) side relative to the vacuum (P2) side. Similarly, output voltage increases as increasing vacuum is applied to the vacuum (P2) side relative to the pressure (P1) side. Preferred devices are Motorola recommended choices for future use and best overall value. Replaces MPX2200/D MPX2202DP CASE 344C 1 Gnd 5 N/C 2 +Vout VS 6 N/C 3 7 N/C 4 -Vout 8 N/C NOTE: Pin 1 is noted by the notch in the lead. MPX2202ASX/GSX CASE 344F PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout MPX2202GVP CASE 344D NOTE: Pin 1 is noted by the notch in the lead. REV 2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-47 Freescale Semiconductor, Inc. MPX2202 MPXV2202G SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 800 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit 0 -- 200 kPa Supply Voltage POP VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS Voff 38.5 40 41.5 mV -1.0 -- 1.0 mV V/P -- 0.2 -- mV/kPa -- - 0.6 - 1.0 -- -- 0.4 1.0 %VFSS -- -- 0.1 -- %VFSS %VFSS Characteristics Pressure Range(1) Freescale Semiconductor, Inc... Full Scale Span(3) Offset(4) Sensitivity Linearity(5) MPX2202D Series MPX2202A Series Pressure Hysteresis(5) (0 to 200 kPa) Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.5 -- TCVFSS TCVoff -2.0 -- 2.0 -1.0 -- 1.0 %VFSS mV Zin Zout 1000 -- 2500 1400 -- 3000 -- 1.0 -- ms Warm-Up tR -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance Output Impedance Response Time(6) (10% to 90%) NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-48 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX2202 Inc. MPXV2202G SERIES LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. LEAST SQUARE DEVIATION LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION straight line. The effects of temperature on Full Scale Span and Offset are very small and are shown under Operating Characteristics. Figure 3 shows the output characteristics of the MPX2202/MPXV2202G series at 25C. The output is directly proportional to the differential pressure and is essentially a VS = 10 Vdc TA = 25C P1 > P2 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 TYP 30 25 SPAN RANGE (TYP) MAX 20 15 10 MIN 5 0 -5 kPa 0 PSI 25 50 7.25 75 100 14.5 150 21.75 125 175 200 29 OFFSET PRESSURE Figure 3. Output versus Pressure Differential SILICONE GEL DIE COAT DIFFERENTIAL/GAUGE STAINLESS STEEL DIE METAL COVER P1 EPOXY CASE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE WIRE BOND LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT P2 DIE BOND SILICONE GEL ABSOLUTE DIE COAT DIE P1 STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE WIRE BOND LEAD FRAME ABSOLUTE ELEMENT P2 DIE BOND Figure 4. Cross-Sectional Diagrams (Not to Scale) Figure 4 illustrates an absolute sensing die (right) and the differential or gauge die in the basic chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX2202/MPXV2202G series pressure sensor oper- Motorola Sensor Device Data ating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-49 Freescale Semiconductor, Inc. MPX2202 MPXV2202G SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing the silicone gel which isolates the die from the environment. The differential or gauge sensor is designed to operate with positive differenPart Number MPX2202A tial pressure applied, P1 > P2. The absolute sensor is designed for vacuum applied to P1 side. The Pressure (P1) side may be identified by using the table below: Case Type MPX2202D MPX2202DP MPX2202AP MPX2202GP MPX2202GVP Freescale Semiconductor, Inc... MPX2202ASX MPX2202GSX Pressure (P1) Side Identifier 344 Stainless Steel Cap 344C Side with Part Marking 344B Side with Port Attached 344D Stainless Steel Cap 344F Side with Port Attached MPXV2202GP 1369 Side with Port Attached MPXV2202DP 1351 Side with Part Marking ORDERING INFORMATION -- UNIBODY PACKAGE (MPX2202 SERIES) MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Absolute, Differential 344 MPX2202A MPX2202D MPX2202A MPX2202D Ported Elements Differential, Dual Port 344C MPX2202DP MPX2202DP Absolute, Gauge 344B MPX2202AP MPX2202GP MPX2202AP MPX2202GP Absolute, Gauge Axial 344F MPX2202ASX MPX2202GSX MPX2202A MPX2202D Gauge, Vacuum 344D MPX2202GVP MPX2202GVP ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV2202G SERIES) Device Type Ported Elements 3-50 Options Case No. MPX Series Order No. Packing Options Marking Gauge, Side Port, SMT 1369 MPXV2202GP Trays MPXV2202G Differential, Dual Port, SMT 1351 MPXV2202DP Trays MPXV2202G For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA High Volume Pressure Sensor For Disposable Applications Motorola has developed a low cost, high volume, miniature pressure sensor package which is ideal as a sub-module component or a disposable unit. The unique concept of the Chip Pak allows great flexibility in system design while allowing an economic solution for the designer. This new chip carrier package uses Motorola's unique sensor die with its piezoresistive technology, along with the added feature of on-chip, thin-film temperature compensation and calibration. NOTE: Motorola is also offering the Chip Pak package in application-specific configurations, which will have an "SPX" prefix, followed by a four-digit number, unique to the specific customer. MPX2300DT1 MPX2301DT1 Motorola Preferred Device PRESSURE SENSORS 0 to 300 mmHg (0 to 40 kPa) Freescale Semiconductor, Inc... Features * Low Cost CHIP PAK PACKAGE * Integrated Temperature Compensation and Calibration * Ratiometric to Supply Voltage * Polysulfone Case Material (Medical, Class V Approved) * Provided in Easy-to-Use Tape and Reel MPX2300/1DT1 CASE 423A Application Examples * Medical Diagnostics * Infusion Pumps * Blood Pressure Monitors PIN NUMBER * Pressure Catheter Applications 1 VS 3 S- * Patient Monitoring 2 S+ 4 Gnd NOTE: The die and wire bonds are exposed on the front side of the Chip Pak (pressure is applied to the backside of the device). Front side die and wire protection must be provided in the customer's housing. Use caution when handling the devices during all processes. Motorola's MPX2300DT1/MPX2301DT1 Pressure Sensors have been designed for medical usage by combining the performance of Motorola's shear stress pressure sensor design and the use of biomedically approved materials. Materials with a proven history in medical situations have been chosen to provide a sensor that can be used with confidence in applications, such as invasive blood pressure monitoring. It can be sterilized using ethylene oxide. The portions of the pressure sensor that are required to be biomedically approved are the rigid housing and the gel coating. The rigid housing is molded from a white, medical grade polysulfone that has passed extensive biological testing including: tissue culture test, rabbit implant, hemolysis, intracutaneous test in rabbits, and system toxicity, USP. A silicone dielectric gel covers the silicon piezoresistive sensing element. The gel is a nontoxic, nonallergenic elastomer system which meets all USP XX Biological Testing Class V requirements. The properties of the gel allow it to transmit pressure uniformly to the diaphragm surface, while isolating the internal electrical connections from the corrosive effects of fluids, such as saline solution. The gel provides electrical isolation sufficient to withstand defibrillation testing, as specified in the proposed Association for the Advancement of Medical Instrumentation (AAMI) Standard for blood pressure transducers. A biomedically approved opaque filler in the gel prevents bright operating room lights from affecting the performance of the sensor. The MPX2301DT1 is a reduced gel option. Preferred devices are Motorola recommended choices for future use and best overall value. REV 5 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-51 MPX2300DT1 MPX2301DT1Freescale Semiconductor, Inc. MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (Backside) Storage Temperature Operating Temperature Symbol Value Unit Pmax 125 PSI Tstg - 25 to + 85 C TA + 15 to + 40 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 6 Vdc, TA = 25C unless otherwise noted) Characteristics Pressure Range Min Typ Max Unit POP 0 -- 300 mmHg Supply Voltage(7) VS -- 6.0 10 Vdc Supply Current Io -- 1.0 -- mAdc Voff - 0.75 -- 0.75 mV -- 4.95 5.0 5.05 V/V/mmHg VFSS 2.976 3.006 3.036 mV Linearity + Hysteresis(2) -- - 1.5 -- 1.5 %VFSS Accuracy(9) VS = 6 V, P = 101 to 200 mmHg -- - 1.5 -- 1.5 % Accuracy(9) VS = 6 V, P = 201 to 300 mmHg -- - 3.0 -- 3.0 % Zero Pressure Offset Freescale Semiconductor, Inc... Symbol Sensitivity Full Scale Span(1) Temperature Effect on Sensitivity TCS - 0.1 -- + 0.1 %/C TCVFSS - 0.1 -- + 0.1 %/C TCVoff - 9.0 -- + 9.0 V/C Zin 1800 -- 4500 Output Impedance Zout 270 -- 330 RCAL (150 k)(8) RCAL 97 100 103 mmHg Response Time(5) (10% to 90%) tR -- 1.0 -- ms Temperature Error Band -- 0 -- 85 C Stability(6) -- -- 0.5 -- %VFSS Temperature Effect on Full Scale Span(3) Temperature Effect on Offset(4) Input Impedance NOTES: 1. Measured at 6.0 Vdc excitation for 100 mmHg pressure differential. VFSS and FSS are like terms representing the algebraic difference between full scale output and zero pressure offset. 2. Maximum deviation from end-point straight line fit at 0 and 200 mmHg. 3. Slope of end-point straight line fit to full scale span at 15C and + 40C relative to + 25C. 4. Slope of end-point straight line fit to zero pressure offset at 15C and + 40C relative to + 25C. 5. For a 0 to 300 mmHg pressure step change. 6. Stability is defined as the maximum difference in output at any pressure within POP and temperature within +10C to + 85C after: a. 1000 temperature cycles, - 40C to +125C. b. 1.5 million pressure cycles, 0 to 300 mmHg. 7. Recommended voltage supply: 6 V 0.2 V, regulated. Sensor output is ratiometric to the voltage supply. Supply voltages above +10 V may induce additional error due to device self-heating. 8. Offset measurement with respect to the measured sensitivity when a 150k ohm resistor is connected to VS and S+ output. 9. Accuracy is calculated using the following equation: Errorp = {[Vp - Offset)/(SensNom*VEX)]-P}/P Where: Vp = Actual output voltage at pressure P in microvolts (V) Offset = Voltage output at P = 0mmHg in microvolts (V) SensNom = Nominal sensitivity = 5.01 V/V/mmHg VEX = Excitation voltage P = Pressure applied to the device 3-52 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX2300DT1 MPX2301DT1 ORDERING INFORMATION The MPX2300DT1/MPX2301DT1 silicon pressure sensors are available in tape and reel packaging. Device Type/Order No. Case No. Device Description Marking MPX2300DT1 423A Chip Pak, Full Gel Date Code, Lot ID MPX2301DT1 423A Chip Pak, 1/3 Gel Date Code, Lot ID Packaging Information Reel Size Tape Width Quantity 330 mm 24 mm 1000 pc/reel Freescale Semiconductor, Inc... Tape and Reel Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-53 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPX4080D Temperature Compensated and Calibrated The MPX4080D series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 80 kPa (0 to 11.6 psi) 0.58 to 4.9 Volts Output Freescale Semiconductor, Inc... Features * 3.0% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems UNIBODY PACKAGE * Temperature Compensated from -40 to 105C * Easy-to-Use, Durable Epoxy Unibody Package Figure 1 shows a block diagram of the internal circuitry integrated on the pressure sensor chip. MPX4080D CASE 867 VS NOTE: Pin 1 is the notched pin. THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY PIN NUMBER Vout PINS 4, 5 AND 6 ARE NO CONNECTS GND 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. Figure 1. Fully Integrated Pressure Sensor Schematic REV 1 3-54 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4080D MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) (P2 > P1) Storage Temperature Symbol Value Unit Pmax 400 400 kPa Tstg - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Freescale Semiconductor, Inc... Characteristic Symbol Min Max Unit -- 80 kPa 5.1 5.35 Vdc 7.0 10 mAdc 0.478 0.575 0.672 Vdc Pressure Range(1) POP 0 Supply Voltage(2) VS 4.85 Supply Current Io -- Voff Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Typ Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.772 4.900 5.020 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.325 -- Vdc -- -- -- "3.0 %VFSS V/P -- 54 -- mV/kPa Accuracy(6) Sensitivity NOTES: 1. 1.0kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS at 25C. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-55 Freescale Semiconductor, Inc. MPX4080D ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION and SIGNAL CONDITIONING 5 VS = 5.1 Vdc TA = 25C MPX4080 4 MAX TYP SPAN RANGE (TYP) 3.5 3 2.5 MIN 2 1.5 OUTPUT RANGE (TYP) 4.5 OUTPUT (V) Figure 2 shows the sensor output signal relative to differential pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. 1 OFFSET (TYP) PRESSURE (kPa) Freescale Semiconductor, Inc... 80 70 60 50 40 30 20 10 0 0 0.5 Figure 2. Output versus Pressure Differential FLUORO SILICONE GEL DIE COAT STAINLESS STEEL METAL COVER EPOXY PLASTIC CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE WIRE BOND DIE BOND LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT Figure 3. Cross-Sectional Diagrams (Not to Scale) than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 3 illustrates the differential sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4080D pressure sensor operating characteristics, internal reliability, and qualification tests are based on use of dry air as the pressure media. Media, other +5 V Vout OUTPUT Vs IPS m 1.0 F m 0.01 F GND 470 pF Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. 3-56 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4080D Transfer Function (MPX4080D) Nominal Transfer Value: Vout = VS (P x 0.01059 + 0.11280) +/- (Pressure Error x Temp. Mult. x 0.01059 x VS) VS = 5.1 V 0.25V P kPa Temperature Error Multiplier Break Points MPX4080D 4.0 3.0 Temp Multiplier - 40 0 to 85 +105 3 1 2 1.0 0.0 -40 -20 0 20 40 60 80 100 120 130 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 105C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Error (kPa) Freescale Semiconductor, Inc... 2.0 1.0 0.0 0 20 40 60 80 100 120 Pressure in kPa -1.0 -2.0 MPX4080D -3.0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Pressure Error (max) 0 to 6 kPa 0 to 60 kPa 60 to 80 kPa 1.8 kPa 1.5 kPa 2.3 kPa 3-57 Freescale Semiconductor, Inc. MPX4080D PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluoro silicone gel which protects the die from harsh media. The Motorola pres- sure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side is identified by the stainless steel cap. ORDERING INFORMATION: The MPX4080D is available only in the unibody package. Device Order No. No Differential Case No No. Device Marking 867 MPX4080D Freescale Semiconductor, Inc... MPX4080D Device Type 3-58 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA MPX4100 SERIES Integrated Silicon Pressure Sensor Manifold Absolute Pressure Sensor On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated INTEGRATED PRESSURE SENSOR 20 to 105 kPa (2.9 to 15.2 psi) 0.3 to 4.9 V Output The Motorola MPX4100 series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The small form factor and high reliability of on-chip integration makes the Motorola MAP sensor a logical and economical choice for automotive system designers. Features * 1.8% Maximum Error Over 0 to 85C * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems * Ideally Suited for Microprocessor Interfacing BASIC CHIP CARRIER ELEMENT CASE 867-08, STYLE 1 * Temperature Compensated Over - 40C to +125C * Durable Epoxy Unibody Element * Ideal for Non-Automotive Applications Application Examples PIN NUMBER * Manifold Sensing for Automotive Systems 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the Lead. VS 3 THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT 2 GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY 1 Vout The MPX4100 series piezoresistive transducer is a state- of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. PINS 4, 5 AND 6 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic REV 5 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-59 Freescale Semiconductor, Inc. MPX4100 SERIES MAXIMUM RATINGS(1) Symbol Value Unit Overpressure(2) (P1 > P2) Parametric Pmax 400 kPa Burst Pressure(2) (P1 > P2) Pburst 1000 kPa Tstg - 40 to +125 C TA - 40 to +125 C Storage Temperature Operating Temperature 1. TC = 25C unless otherwise noted. 2. Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 20 -- 105 kPa Supply Voltage(1) VS 4.85 5.1 5.35 Vdc Freescale Semiconductor, Inc... Supply Current Io -- 7.0 10 mAdc Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.225 0.306 0.388 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.815 4.897 4.978 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.59 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.8 %VFSS mV/kPa Sensitivity V/P -- 54 -- Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS Symbol Min Typ Max Unit Weight, Basic Element (Case 867) -- -- 4.0 -- Grams Common Mode Line Pressure(10) -- -- -- 690 kPa Decoupling circuit shown in Figure 3 required to meet electrical specifications. MECHANICAL CHARACTERISTICS Characteristic NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 10. Common mode pressures beyond specified may result in leakage at the case-to-lead interface. 3-60 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. FLUORO SILICONE GEL DIE COAT DIE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE P1 WIRE BOND LEAD FRAME +5 V STAINLESS STEEL CAP EPOXY PLASTIC CASE m 1.0 F 3 1 IPS 2 OUTPUT m 0.01 F DIE BOND ABSOLUTE ELEMENT P2 MPX4100 SERIES SEALED VACUUM REFERENCE Figure 3. Recommended Power Supply Decoupling. For output filtering recommendations, please refer to Application Note AN1646. Figure 2 illustrates an absolute sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4100A series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C. (The output will saturate outside of the specified pressure range.) 5.0 4.5 4.0 OUTPUT (Volts) 3.5 3.0 TRANSFER FUNCTION: Vout = Vs* (.01059*P-.152) Error VS = 5.1 Vdc TEMP = 0 to 85C 20 kPa TO 105 kPa MPX4100A MAX TYP 2.5 2.0 1.5 1.0 MIN 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram (Not to Scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-61 Freescale Semiconductor, Inc. MPX4100 SERIES Transfer Function (MPX4100A) Nominal Transfer Value: Vout = VS (P x 0.01059 - 0.1518) +/- (Pressure Error x Temp. Factor x 0.01059 x VS) VS = 5.1 V 0.25 Vdc Temperature Error Band MPX4100A Series 4.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 3.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 3-62 Pressure Error (Max) 20 to 105 (kPa) 1.5 (kPa) For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4100 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluorosilicone gel which protects the die from harsh media. The Motorola MPX Freescale Semiconductor, Inc... Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX4100A 867-08 Stainless Steel Cap MPX4100AP 867B-04 Side with Port Marking MPX4100AS 867E-03 Side with Port Attached MPX4100ASX 867F-03 Side with Port Attached ORDERING INFORMATION The MPX4100A series MAP silicon pressure sensors are available in the Basic Element, or with pressure port fittings that provide mounting ease and barbed hose connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Absolute, Element Only 867-08 MPX4100A MPX4100A Ported Elements Absolute, Ported 867B-04 MPX4100AP MPX4100AP Absolute, Stove Pipe Port 867E-03 MPX4100AS MPX4100A Absolute, Axial Port 867F-03 MPX4100ASX MPX4100A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-63 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX4100A for Manifold Absolute Pressure MPXA4100A Applications SERIES On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated INTEGRATED PRESSURE SENSOR 15 to 115 kPa (2.2 to 16.7 psi) 0.2 to 4.8 Volts Output The Motorola MPX4100A/MPXA4100A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The small form factor and high reliability of on-chip integration makes the Motorola MAP sensor a logical and economical choice for automotive system designers. The MPX4100A/MPXA4100A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. UNIBODY PACKAGE MPX4100A CASE 867 Features * 1.8% Maximum Error Over 0 to 85C * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems * Temperature Compensated Over - 40C to +125C * Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package SMALL OUTLINE PACKAGE Application Examples * Manifold Sensing for Automotive Systems * Ideally suited for Microprocessor or Microcontroller- Based Systems MPX4100AP CASE 867B MPXA4100A6U CASE 482 * Also Ideal for Non-Automotive Applications VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY MPXA4100AC6U CASE 482A Vout MPX4100AS CASE 867E PIN NUMBER PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND PINS 4, 5 AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE Figure 1. Fully Integrated Pressure Sensor Schematic REV 5 3-64 PIN NUMBER 1 N/C 5 N/C 1 Vout 4 N/C 2 VS Gnd 6 N/C 2 Gnd 5 N/C 3 7 N/C 3 VS 6 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor,MPX4100A Inc. MPXA4100A SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 u P2) Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C TA -40 to +125 C Storage Temperature Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Symbol Min Typ Max Unit Pressure Range(1) POP 20 -- 105 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Freescale Semiconductor, Inc... Characteristic Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.225 0.306 0.388 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.870 4.951 5.032 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.59 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.8 %VFSS Sensitivity V/P -- 54 -- mV/kPa Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Typ Unit Weight, Basic Element (Case 867) 4.0 grams Weight, Small Outline Package (Case 482) 1.5 grams Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-65 Freescale Semiconductor, Inc. MPX4100A MPXA4100A SERIES FLUORO SILICONE GEL DIE COAT DIE +5 V STAINLESS STEEL CAP Vout P1 WIRE BOND Vs THERMOPLASTIC CASE LEAD FRAME IPS m 1.0 F ABSOLUTE ELEMENT OUTPUT m 0.01 F GND 470 pF DIE BOND SEALED VACUUM REFERENCE Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Figure 2 illustrates the absolute sensing chip in the basic chip carrier (Case 482). Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 3.0 TRANSFER FUNCTION: Vout = Vs* (.01059*P-.152) Error VS = 5.1 Vdc TEMP = 0 to 85C 20 kPa TO 105 kPa MPX4100A MAX TYP 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SOP (not to scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C. The output will saturate outside of the specified pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The 3-66 MPX4100A/MPXA4100A series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor,MPX4100A Inc. MPXA4100A SERIES Transfer Function (MPX4100A, MPXA4100A) Nominal Transfer Value: Vout = VS (P x 0.01059 - 0.1518) +/- (Pressure Error x Temp. Factor x 0.01059 x VS) VS = 5.1 V 0.25 Vdc Temperature Error Band MPX4100A, MPXA4100A Series 4.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 3.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 Motorola Sensor Device Data Pressure Error (Max) 20 to 105 (kPa) 1.5 (kPa) www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-67 Freescale Semiconductor, Inc. MPX4100A MPXA4100A SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluorosilicone gel which protects the die from harsh media. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX4100A 867 Stainless Steel Cap MPX4100AP 867B Side with Port Marking MPX4100AS 867E Side with Port Attached MPXA4100A6U/T1 482 Stainless Steel Cap MPXA4100AC6U 482A Side with Port Attached Freescale Semiconductor, Inc... ORDERING INFORMATION -- UNIBODY PACKAGE MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Absolute, Element Only 867 MPX4100A MPX4100A Ported Elements Absolute, Ported 867B MPX4100AP MPX4100AP Absolute, Stove Pipe Port 867E MPX4100AS MPX4100A ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXA4100A6U Rails MPXA4100A Absolute, Element Only 482 MPXA4100A6T1 Tape and Reel MPXA4100A Absolute, Axial Port 482A MPXA4100AC6U Rails MPXA4100A Ported Element 3-68 MPX Series Order No. Packing Options For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking Motorola Sensor Device Data Freescale Semiconductor,MPX4100A Inc. MPXA4100A SERIES INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct footprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-69 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA MPX4101A Integrated Silicon Pressure Sensor MPXA4101A for Manifold Absolute Pressure MPXH6101A Applications SERIES On-Chip Signal Conditioned, Temperature Compensated INTEGRATED PRESSURE SENSOR 15 to 102 kPa (2.18 to 14.8 psi) 0.25 to 4.95 V Output Freescale Semiconductor, Inc... and Calibrated The Motorola MPX4101A/MPXA4101A/MPXH6101A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The small form factor and high reliability of on-chip integration makes the Motorola MAP sensor a logical and economical choice for automotive system designers. The MPX4101A/MPXA4101A/MPXH6101A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. SMALL OUTLINE PACKAGE MPXA4101AC6U CASE 482A Features * 1.72% Maximum Error Over 0 to 85C PIN NUMBER * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems * Temperature Compensated Over - 40C to +125C * Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package Application Examples 1 N/C 5 N/C 2 VS Gnd 6 N/C 3 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are not device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. * Manifold Sensing for Automotive Systems * Ideally Suited for Microprocessor or Microcontroller-Based Systems * Also Ideal for Non-Automotive Applications SUPER SMALL OUTLINE PACKAGE UNIBODY PACKAGE MPXH6101A6T1 CASE 1317 MPX4101A CASE 867 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE DEVICE GND PINS 4, 5 AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE Figure 1. Fully Integrated Pressure Sensor Schematic Vout PIN NUMBER PIN NUMBER 1 N/C 5 N/C 1 Vout 4 N/C 2 VS Gnd 6 N/C 2 Gnd 5 N/C 3 7 N/C 3 VS 6 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the chamfered corner of the package. NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 4 3-70 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4101A MPXA4101A MPXH6101A SERIES MAXIMUM RATINGS(NOTE) Parametric Maximum Pressure (P1 > P2) Storage Temperature Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C TA - 40 to +125 C Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Symbol Min Typ Max Unit Pressure Range(1) POP 15 -- 102 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Freescale Semiconductor, Inc... Characteristic Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.171 0.252 0.333 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.870 4.951 5.032 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.7 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.72 %VFSS Sensitivity V/P -- 54 -- mV/kPa Response Time(7) tR -- 15 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-71 Freescale Semiconductor, Inc. MPX4101A MPXA4101A MPXH6101A SERIES DIE FLUORO SILICONE GEL DIE COAT STAINLESS STEEL CAP P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME ABSOLUTE ELEMENT DIE BOND SEALED VACUUM REFERENCE Figure 2 illustrates an absolute sensing chip in the super small outline package (Case 1317). 5.0 +5.1 V 4.5 4.0 VS Pin 2 100 nF MPXH6101A Vout Pin 4 GND Pin 3 to ADC 47 pF 51 K OUTPUT (Volts) 3.5 3.0 TRANSFER FUNCTION: Vout = Vs* (PX0.01059*P-0.10941) Error VS = 5.1 Vdc TEMP = 0 to 85C MAX 20 kPa TO 105 kPa MPX4101A TYP 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SSOP (not to scale) Pressure (ref: to sealed vacuum) in kPa Figure 3. Recommended power supply decoupling and output filtering. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C. The output will saturate outside of the specified pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4101A/MPXA4101A/MPXH6101A series pressure sensor operating characteristics, and internal reliability and qual- 3-72 Figure 4. Output versus Absolute Pressure ification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4101A MPXA4101A MPXH6101A SERIES Transfer Function (MPX4101A, MPXA4101A, MPXH6101A) Nominal Transfer Value: Vout = VS (P x 0.01059 - 0.10941) +/- (Pressure Error x Temp. Factor x 0.01059 x VS) VS = 5.1 V 0.25 Vdc Temperature Error Band MPX4101A, MPXA4101A, MPXH6101A Series 4.0 3.0 2.0 Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to - 40C and from 85 to 125C. Pressure Error Band Error Limits for Pressure 3.0 Pressure Error (kPa) Freescale Semiconductor, Inc... Temperature Error Factor Temp 2.0 1.0 0.0 Pressure (in kPa) 0 15 30 45 60 75 90 105 120 -1.0 - 2.0 - 3.0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Pressure Error (Max) 15 to 102 (kPa) 1.5 (kPa) 3-73 Freescale Semiconductor, Inc. MPX4101A MPXA4101A MPXH6101A SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluorosilicone gel which protects the die from harsh media. The Motorola pres- Part Number sure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX4101A 867 Stainless Steel Cap MPXA4101AC6U 482A Side with Port Attached MPXH6101A6U 1317 Stainless Steel Cap MPXH6101A6T1 1317 Stainless Steel Cap Freescale Semiconductor, Inc... ORDERING INFORMATION -- UNIBODY PACKAGE The MPX4101A series MAP silicon pressure sensors are available in the Basic Element, or with pressure port fittings that provide mounting ease and barbed hose connections. MPX Series Device Type Basic Element Options Case Type Absolute, Element Only 867 Order Number Device Marking MPX4101A MPX4101A ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Ported Element Options Case No. Absolute, Axial Port 482A MPX Series Order No. MPXA4101AC6U Packing Options Rails Marking MPXA4101A ORDERING INFORMATION -- SUPER SMALL OUTLINE PACKAGE Device Type Options Case No. MPX Series Order No. Packing Options Marking Basic Element Absolute, Element Only 1317 MPXH6101A6U Rails MPXH6101A Basic Element Absolute, Element Only 1317 MPXH6101A6T1 Tape and Reel MPXH6101A INFORMATION FOR USING THE SMALL OUTLINE PACKAGES MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct footprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 0.050 1.27 TYP 0.387 9.83 0.150 3.81 0.060 TYP 8X 1.52 0.300 7.62 0.027 TYP 8X 0.69 0.100 TYP 8X 2.54 inch mm Figure 5. SOP Footprint (Case 482) 3-74 0.053 TYP 8X 1.35 SCALE 2:1 inch mm Figure 6. SSOP Footprint (Case 1317) For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor for Manifold Absolute Pressure MPX4105A SERIES Applications On-Chip Signal Conditioned, Temperature Compensated INTEGRATED PRESSURE SENSOR 15 to 105 kPa (2.2 to 15.2 psi) 0.3 to 4.9 V Output Freescale Semiconductor, Inc... and Calibrated The Motorola MPX4105A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. Motorola's MAP sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola MAP sensor a logical and economical choice for the automotive system designer. The MPX4105A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. UNIBODY PACKAGE MPX4105A CASE 867 Features * 1.8% Maximum Error Over 0 to 85C * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems 1 Vout 4 N/C * Temperature Compensated Over - 40 to +125C 2 Gnd 5 N/C 3 VS 6 N/C PIN NUMBER * Durable Epoxy Unibody Element Application Examples * Manifold Sensing for Automotive Systems * Ideally Suited for Microprocessor or Microcontroller-Based Systems NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. * Also Ideal for Non-Automotive Applications VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GND GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5 AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE Figure 1. Fully Integrated Pressure Sensor Schematic REV 4 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-75 MPX4105A SERIES Freescale Semiconductor, Inc. MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 u P2) Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C TA -40 to +125 C Storage Temperature Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted. Decoupling circuit shown in Figure 3 required to meet specification.) Symbol Min Typ Max Unit POP 15 -- 105 kPa Supply Voltage(1) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Characteristic Freescale Semiconductor, Inc... Pressure Range Minimum Pressure Offset(2) (0 to 85C) Voff 0.184 0.306 0.428 Vdc Full Scale Output(3) (0 to 85C) VFSO 4.804 4.896 4.988 Vdc Full Scale Span(4) (0 to 85C) VFSS -- 4.590 -- Vdc Accuracy(5) (0 to 85C) -- -- -- 1.8 %VFSS V/P -- 51 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-up Time(7) -- -- 15 -- ms Offset Stability(8) -- -- 0.65 -- %VFSS Sensitivity NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with minimum specified pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Span deviation per C over the temperature range of 0 to 85C, as a percent of span at 25C. * TcOffset: Output deviation per C with minimum pressure applied, over the temperature range of 0 to 85C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage. 8. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) 3-76 Typ Unit 4.0 grams For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. FLUORO SILICONE GEL DIE COAT +5 V STAINLESS STEEL CAP DIE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE P1 WIRE BOND LEAD FRAME EPOXY PLASTIC CASE Vout OUTPUT Vs IPS m 1.0 F DIE BOND ABSOLUTE ELEMENT P2 SEALED VACUUM REFERENCE Figure 2. Cross-Sectional Diagram (not to scale) m GND 0.01 F 470 pF Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 2 illustrates an absolute sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4105A series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may 5.0 4.5 4.0 OUTPUT (Volts) 3.5 3.0 TRANSFER FUNCTION: Vout = Vs* (0.01*P-0.09) Error VS = 5.1 Vdc TEMP = 0 to 85C 15 kPA TO 105 kPA MPX4105A MAX TYP 2.5 2.0 1.5 MIN 1.0 0.5 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 Freescale Semiconductor, Inc... MPX4105A SERIES Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over a temperature range of 0 to Motorola Sensor Device Data 85C. The output will saturate outside of the specified pressure range. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-77 Freescale Semiconductor, Inc. MPX4105A SERIES Transfer Function (MPX4105A) Nominal Transfer Value: Vout = VS (P x 0.01 - 0.09) +/- (Pressure Error x Temp. Factor x 0.01 x VS) VS = 5.1 V 0.25 Vdc Temperature Error Band MPX4105A Series 4.0 Break Points 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 - 20 0 to 85 125 3.0 1.5 1.0 2.5 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from -40C to -20C, -20C to 0C, and from 85C to 125C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 1.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 Pressure Error (Max) 40 to 94 (kPa) 15 (kPa) 105 (kPa) 1.5 (kPa) 2.4 (kPa) 1.8 (kPa) ORDERING INFORMATION -- UNIBODY PACKAGE Device Type Basic Element 3-78 Options Absolute Element Absolute, Case No No. 867 MPX Series Order No No. MPX4105A For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking MPX4105A Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor for Manifold Absolute Pressure, Altimeter or Barometer Applications MPX4115A MPXA4115A SERIES On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated Motorola's MPX4115A/MPXA4115A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPX4115A/MPXA4115A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. INTEGRATED PRESSURE SENSOR 15 to 115 kPa (2.2 to 16.7 psi) 0.2 to 4.8 Volts Output UNIBODY PACKAGE Features * 1.5% Maximum Error over 0 to 85C MPX4115A CASE 867 * Ideally suited for Microprocessor or Microcontroller- Based Systems * Temperature Compensated from - 40 to +125C * Durable Epoxy Unibody Element or Thermoplastic (PPS) Surface Mount Package Application Examples SMALL OUTLINE PACKAGE * Aviation Altimeters * Industrial Controls * Engine Control * Weather Stations and Weather Reporting Devices THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout MPXA4115AC6U CASE 482A PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND PINS 4, 5 AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE Figure 1. Fully Integrated Pressure Sensor Schematic REV 4 Motorola Sensor Device Data MPX4115AP CASE 867B MPXA4115A6U CASE 482 VS MPX4115AS CASE 867E PIN NUMBER PIN NUMBER 1 N/C 5 N/C 1 Vout 4 N/C 2 VS Gnd 6 N/C 2 Gnd 5 N/C 3 7 N/C 3 VS 6 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. 3-79 Freescale Semiconductor, Inc. MPX4115A MPXA4115A SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 u P2) Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C TA -40 to +125 C Storage Temperature Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 required to meet Electrical Specifications.) Characteristic Symbol Min Typ Max Unit POP 15 -- 115 kPa Supply Voltage(1) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2. Decoupling circuit shown in Figure 3 Minimum Pressure Offset(2) @ VS = 5.1 Volts (0 to 85C) Voff 0.135 0.204 0.273 Vdc Full Scale Output(3) @ VS = 5.1 Volts (0 to 85C) VFSO 4.725 4.794 4.863 Vdc Full Scale Span(4) @ VS = 5.1 Volts (0 to 85C) VFSS 4.521 4.590 4.659 Vdc Accuracy(5) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 45.9 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(7) -- -- 20 -- ms Offset Stability(8) -- -- 0.5 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Typ Unit Weight, Basic Element (Case 867) 4.0 grams Weight, Small Outline Package (Case 482) 1.5 grams 3-80 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor,MPX4115A Inc. MPXA4115A SERIES FLUORO SILICONE GEL DIE COAT +5 V DIE STAINLESS STEEL CAP Vout P1 WIRE BOND Vs THERMOPLASTIC CASE LEAD FRAME IPS m 1.0 F ABSOLUTE ELEMENT OUTPUT m GND 0.01 F 470 pF DIE BOND SEALED VACUUM REFERENCE Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Figure 2 illustrates the absolute sensing chip in the basic chip carrier (Case 482). Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 MAX TRANSFER FUNCTION: Vout = Vs* (.009*P-.095) Error VS = 5.1 Vdc TEMP = 0 to 85C TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SOP (not to scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over 0 to 85C temperature range. The output will saturate outside of the rated pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The Motorola Sensor Device Data MPX4115A/MPXA4115A series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-81 Freescale Semiconductor, Inc. MPX4115A MPXA4115A SERIES Transfer Function (MPX4115A, MPXA4115A) Nominal Transfer Value: Vout = VS x (0.009 x P - 0.095) (Pressure Error x Temp. Factor x 0.009 x VS) VS = 5.1 0.25 Vdc Temperature Error Band MPX4115A, MPXA4115A Series 4.0 Break Points 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 125 3 1 3 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 1.0 0.0 20 40 60 80 100 Pressure (in kPa) 120 -1.0 - 2.0 - 3.0 Pressure Error (Max) 15 to 115 (kPa) 1.5 (kPa) ORDERING INFORMATION -- UNIBODY PACKAGE Device Type Options Case No. MPX Series Order No. Marking Basic Element Absolute, Element Only 867 MPX4115A MPX4115A Ported Elements Absolute, Ported 867B MPX4115AP MPX4115AP Absolute, Stove Pipe Port 867E MPX4115AS MPX4115A ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXA4115A6U Rails MPXA4115A Absolute, Element Only 482 MPXA4115A6T1 Tape and Reel MPXA4115A Absolute, Axial Port 482A MPXA4115AC6U Rails MPXA4115A Absolute, Axial Port 482A MPXA4115AC6T1 Tape and Reel MPXA4115A Ported Element 3-82 MPX Series Order No. Packing Options For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking Motorola Sensor Device Data Freescale Semiconductor,MPX4115A Inc. MPXA4115A SERIES INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-83 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX4200A for Manifold Absolute Pressure SERIES Applications On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated The Motorola MPX4200A series Manifold Absolute Pressure (MAP) sensor for turbo boost engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The MPX4200A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high level analog output signal and temperature compensation. The small form factor and reliability of on-chip integration make the Motorola MAP sensor a logical and economical choice for automotive system designers. INTEGRATED PRESSURE SENSOR 20 to 200 kPa (2.9 to 29 psi) 0.3 to 4.9 V OUTPUT Features * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems MPX4200A CASE 867 * Patented Silicon Shear Stress Strain Gauge * Temperature Compensated Over - 40 to +125C * Offers Reduction in Weight and Volume Compared to Existing Hybrid Modules PIN NUMBER * Durable Epoxy Unibody Element 1 Vout 4 N/C Application Examples 2 Gnd 5 N/C * Manifold Sensing for Automotive Systems 3 VS 6 N/C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Also ideal for Non-Automotive Applications NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5 AND 6 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic Rev 1 3-84 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4200A SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 800 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Freescale Semiconductor, Inc... Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 20 -- 200 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.199 0.306 0.413 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.725 4.896 4.978 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.590 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 25.5 -- mV/kPa Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output lo+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) Motorola Sensor Device Data Typ Unit 4.0 grams www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-85 Freescale Semiconductor, Inc. MPX4200A SERIES SILICONE DIE COAT +5 V STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 WIRE BOND LEAD FRAME P2 EPOXY CASE Vout OUTPUT Vs IPS m RTV DIE BOND 1.0 F m GND 0.01 F 470 pF SEALED VACUUM REFERENCE Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over temperature range of 0 to 85C. The output will saturate outside of the specified pressure range. Figure 2 illustrates the absolute sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4200A series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 TRANSFER FUNCTION: Vout = VS* (0.005 x P-0.04) Error VS = 5.1 Vdc TEMP = 0 to 85C MAX TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 Freescale Semiconductor, Inc... Figure 2. Cross-Sectional Diagram (Not to Scale) Figure 4. Output versus Absolute Pressure 3-86 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX4200A SERIES Transfer Function (MPX4200A) Nominal Transfer Value: Vout = VS x (0.005 x P - 0.04) Nominal Transfer Value: (Pressure Error x Temp. Factor x 0.005 x VS) Nominal Transfer Value: VS = 5.1 0.25 Vdc Temperature Error Band MPX4200A Series 4.0 Temperature Error Factor 2.0 Temp Multiplier - 40 -18 0 to 85 +125 3 1.56 1 2 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band 6.0 4.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 3.0 2.0 20 40 60 80 Pressure in kPa 100 120 140 160 180 200 -2.0 - 4.0 MPX4200A Series - 6.0 Pressure Error (Max) 20 kPa 40 kPa 160 kPa 200 kPa 4.2 (kPa) 2.4 (kPa) 2.4 (kPa) 3.2 (kPa) ORDERING INFORMATION Device Type Basic Element Options Absolute, Element Motorola Sensor Device Data Case No. Case 867 MPX Series Order No. MPX4200A www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Marking MPX4200A 3-87 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX4250A Manifold Absolute Pressure Sensor MPXA4250A On-Chip Signal Conditioned, SERIES Temperature Compensated Freescale Semiconductor, Inc... and Calibrated INTEGRATED PRESSURE SENSOR 20 to 250 kPa (2.9 to 36.3 psi) 0.2 to 4.9 V OUTPUT The Motorola MPX4250A/MPXA4250A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The MPX4250A/MPXA4250A series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller or microprocessor with A/D inputs. This transducer combines advanced micromachining techniques, thin-film metallization and bipolar processing to provide an accurate, high-level analog output signal that is proportional to the applied pressure. The small form factor and high reliability of on-chip integration make the Motorola sensor a logical and economical choice for the automotive system engineer. UNIBODY PACKAGE SMALL OUTLINE PACKAGE Features * 1.5% Maximum Error Over 0 to 85C BASIC CHIP CARRIER ELEMENT CASE 867, STYLE 1 * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems * Patented Silicon Shear Stress Strain Gauge * Temperature Compensated Over - 40 to +125C PORT OPTION CASE 482 * Offers Reduction in Weight and Volume Compared to Existing Hybrid Modules * Durable Epoxy Unibody Element or Thermoplastic Small Outline, Surface Mount Package * Ideal for Non-Automotive Applications Application Examples * Turbo Boost Engine Control * Ideally Suited for Microprocessor or Microcontroller- Based Systems PORT OPTION CASE 867B, STYLE 1 PORT OPTION CASE 482A PIN NUMBER PIN NUMBER VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GND GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout 1 N/C 5 N/C 1 Vout 4 N/C 2 VS Gnd 6 N/C 2 Gnd 5 N/C 3 7 N/C 3 VS 6 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, and 7 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. PINS 4, 5, AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE PINS 1, 5, 6, 7, AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE Figure 1. Fully Integrated Pressure Sensor Schematic REV 4 3-88 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor,MPX4250A Inc. MPXA4250A SERIES MAXIMUM RATINGS(1) Parametrics Maximum Pressure(2) (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 1000 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTES: 1. TC = 25C unless otherwise noted. 2. Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2, Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Symbol Min Typ Max Unit Pressure Range(1) POP 20 -- 250 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Freescale Semiconductor, Inc... Characteristic Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.133 0.204 0.274 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.826 4.896 4.966 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.692 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.5 %VFSS V/P -- 20 -- mV/kPa Response Time(7) tR -- 1.0 -- msec Output Source Current at Full Scale Output lo+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- msec Offset Stability(9) -- -- 0.5 -- %VFSS Sensitivity NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Typ Unit Weight, Basic Element (Case 867) 4.0 Grams Weight, Small Outline Package (Case 482) 1.5 Grams Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-89 Freescale Semiconductor, Inc. MPX4250A MPXA4250A SERIES FLUOROSILICONE DIE COAT +5 V STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 WIRE BOND LEAD FRAME P2 Vout EPOXY CASE OUTPUT Vs IPS RTV DIE BOND m 1.0 F m GND 0.01 F 470 pF SEALED VACUUM REFERENCE Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Contact the factory for information regarding media compatibility in your application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over temperature range of 0 to 85C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. Figure 2 illustrates the absolute pressure sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4250A/MPXA4250A series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 TRANSFER FUNCTION: Vout = VS* (0.004 x P-0.04) Error VS = 5.1 Vdc TEMP = 0 to 85C MAX TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 Freescale Semiconductor, Inc... Figure 2. Cross-Sectional Diagram (Not to Scale) PRESSURE (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure 3-90 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor,MPX4250A Inc. MPXA4250A SERIES Transfer Function Nominal Transfer Value: Vout = VS (P x 0.004 - 0.04) Nominal Transfer Value: +/- (Pressure Error x Temp. Factor x 0.004 x VS) Nominal Transfer Value: VS = 5.1 V 0.25 Vdc Temperature Error Band 4.0 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 Freescale Semiconductor, Inc... 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band 5.0 4.0 Pressure Error (kPa) 3.0 2.0 1.0 0 -1.0 -2.0 -3.0 -4.0 -5.0 Motorola Sensor Device Data 0 25 50 75 100 125 150 175 200 225 250 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Pressure (kPa) Pressure Error (Max) 20 to 250 kPa 3.45 (kPa) 3-91 Freescale Semiconductor, Inc. MPX4250A MPXA4250A SERIES ORDERING INFORMATION - UNIBODY PACKAGE (CASE 867) The MPX4250A series pressure sensors are available in the basic element package or with pressure port fittings that provide mounting ease and barbed hose connections. Device Type/Order No. Options Case No. Marking MPX4250A MPX4250A Basic Element 867 MPX4250AP Ported Element 867B MPX4250AP ORDERING INFORMATION - SMALL OUTLINE PACKAGE (CASE 482) The MPXA4250A series pressure sensors are available in the basic element package or with a pressure port fitting. Two packing options are offered for each type. Freescale Semiconductor, Inc... Device Type/Order No. Case No. Packing Options Device Marking MPXA4250A6U 482 Rails MPXA4250A MPXA4250A6T1 482 Tape and Reel MPXA4250A MPXA4250AC6U 482A Rails MPXA4250A MPXA4250AC6T1 482A Tape and Reel MPXA4250A INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) 3-92 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX4250D On-Chip Signal Conditioned, SERIES Temperature Compensated Freescale Semiconductor, Inc... and Calibrated The MPX4250D series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller or microprocessor with A/D inputs. This transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high-level analog output signal that is proportional to the applied pressure. The small form factor and high reliability of on-chip integration make the Motorola sensor a logical and economical choice for the automotive system engineer. INTEGRATED PRESSURE SENSOR 0 to 250 kPa (0 to 36.3 psi) 0.2 to 4.9 Volts Output UNIBODY PACKAGE Features * Differential and Gauge Applications Available * 1.4% Maximum Error Over 0 to 85C * Patented Silicon Shear Stress Strain Gauge BASIC CHIP CARRIER ELEMENT CASE 867, STYLE 1 * Temperature Compensated Over - 40 to +125C * Offers Reduction in Weight and Volume Compared to Existing Hybrid Modules * Durable Epoxy Unibody Element Applications * Ideally Suited for Microprocessor or Microcontroller-Based Systems VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY GAUGE PORT OPTION CASE 867B, STYLE 1 Vout PINS 4, 5 AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE GND Figure 1. Fully Integrated Pressure Sensor Schematic DUAL PORT OPTION CASE 867C, STYLE 1 PIN NUMBER 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-93 MPX4250D SERIES Freescale Semiconductor, Inc. MAXIMUM RATINGS(1) Parametrics Maximum Pressure(2) (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 1000 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTES: 1. TC = 25C unless otherwise noted. 2. Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2, Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 250 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Freescale Semiconductor, Inc... Characteristic Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) VOFF 0.139 0.204 0.269 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.844 4.909 4.974 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.705 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.4 %VFSS V/P -- 18.8 -- mV/kPa Response Time(7) tR -- 1.0 -- msec Output Source Current at Full Scale Output lo+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- msec Offset Stability(9) -- -- 0.5 -- %VFSS Sensitivity NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) 3-94 Typ Unit 4.0 Grams For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. FLUOROSILICONE DIE COAT DIE +5 V STAINLESS STEEL METAL COVER EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE P1 Vout WIRE BOND LEAD FRAME MPX4250D SERIES OUTPUT Vs IPS RTV DIE BOND m 1.0 F m GND 0.01 F 470 pF P2 EPOXY CASE Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. Figure 2 illustrates the differential/gauge pressure sensing chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX4250D series pressure sensor operating characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 MAX TRANSFER FUNCTION: Vout = VS* (0.00369*P + 0.04) Error VS = 5.1 Vdc TEMP = 0 to 85C TYP 3.0 2.5 2.0 1.5 MIN 1.0 0 250 260 0.5 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 Freescale Semiconductor, Inc... Figure 2. Cross-Sectional Diagram (Not to Scale) PRESSURE in kPa Figure 4. Output versus Differential Pressure Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-95 Freescale Semiconductor, Inc. MPX4250D SERIES Transfer Function (MPX4250D) Nominal Transfer Value: Vout = VS x (0.00369 x P + 0.04) Nominal Transfer Value: (Pressure Error x Temp. Factor x 0.00369 x VS) Nominal Transfer Value: VS = 5.1 0.25 Vdc " " Temperature Error Band 4.0 Freescale Semiconductor, Inc... 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band 5.0 4.0 Pressure Error (kPa) 3.0 2.0 1.0 0 -1.0 -2.0 -3.0 -4.0 -5.0 0 25 50 75 100 125 150 175 200 225 250 Pressure (kPa) Pressure Error (max) 0 to 250 kPa 3.45 kPa ORDERING INFORMATION The MPX4250D series silicon pressure sensors are available in the basic element package or with pressure port fittings that provide mounting ease and barbed hose connections. Device Type/Order No. Options Case No. Marking 867 MPX4250D MPX4250D Basic Element MPX4250GP Gauge Ported Element 867B MPX4250GP MPX4250DP Dual Ported Element 867C MPX4250DP 3-96 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPX5010 MPXV5010G Temperature Compensated Freescale Semiconductor, Inc... and Calibrated SERIES Motorola Preferred Device SMALL OUTLINE PACKAGE The MPX5010/MPXV5010G series piezoresistive transducers are state-of-the-art monolithic silicon pressure sensors designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 10 kPa (0 to 1.45 psi) 0.2 to 4.7 V Output MPXV5010G6U CASE 482 UNIBODY PACKAGE Features * 5.0% Maximum Error over 0 to 85C * Ideally Suited for Microprocessor or Microcontroller- Based Systems MPXV5010GC6U CASE 482A * Durable Epoxy Unibody and Thermoplastic (PPS) Surface Mount Package * Temperature Compensated over MPX5010D CASE 867 *40 to +125C * Patented Silicon Shear Stress Strain Gauge * Available in Differential and Gauge Configurations * Available in Surface Mount (SMT) or Through-hole (DIP) Configurations MPXV5010GC7U CASE 482C Application Examples * Hospital Beds * HVAC * Respiratory Systems MPX5010DP CASE 867C * Process Control MPXV5010GP CASE 1369 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 1 AND 5 THROUGH 8 ARE NO CONNECTS FOR SURFACE MOUNT PACKAGE GND PINS 4, 5, AND 6 ARE NO CONNECTS FOR UNIBODY PACKAGE Figure 1. Fully Integrated Pressure Sensor Schematic MPXV5010DP CASE 1351 MPX5010GS CASE 867E PIN NUMBER PIN NUMBER 1 N/C 5 N/C 1 Vout 4 N/C 2 6 N/C 2 Gnd 5 N/C 3 VS Gnd 7 N/C 3 VS 6 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 9 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-97 Freescale Semiconductor, Inc. MPX5010 MPXV5010G SERIES MAXIMUM RATINGS(NOTE) Parametrics Symbol Value Unit Pmax 75 kPa Tstg - 40 to +125 C TA - 40 to +125 C Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet specification.) Freescale Semiconductor, Inc... Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 10 kPa Supply Voltage(2) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 5.0 10 mAdc Minimum Pressure Offset(3) @ VS = 5.0 Volts (0 to 85C) Voff 0 0.2 0.425 Vdc Full Scale Output(4) @ VS = 5.0 Volts (0 to 85C) VFSO 4.475 4.7 4.925 Vdc Full Scale Span(5) @ VS = 5.0 Volts (0 to 85C) VFSS 4.275 4.5 4.725 Vdc Accuracy(6) (0 to 85C) -- -- -- 5.0 %VFSS V/P -- 450 -- mV/kPa tR -- 1.0 -- ms Sensitivity Response Time(7) Output Source Current at Full Scale Output IO+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Typ Unit Weight, Basic Element (Case 867) 4.0 grams Weight, Basic Element (Case 482) 1.5 grams 3-98 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX5010 Inc. MPXV5010G SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING DIE FLUOROSILICONE GEL DIE COAT sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 3 shows the recommended decoupling circuit for interfacing the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. +5 V STAINLESS STEEL CAP P1 Vout WIRE BOND IPS m m 1.0 F LEAD FRAME OUTPUT Vs THERMOPLASTIC CASE GND 0.01 F 470 pF P2 DIE BOND DIFFERENTIAL SENSING ELEMENT Figure 2. Cross-Sectional Diagram SOP (Not to Scale) Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. 5.0 OUTPUT (V) Freescale Semiconductor, Inc... The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip. Figure 2 illustrates the Differential or Gauge configuration in the basic chip carrier (Case 482). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX5010 and MPXV5010G series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on TRANSFER FUNCTION: 4.5 V = V *(0.09*P+0.04) ERROR out S 4.0 VS = 5.0 Vdc TEMP = 0 to 85C 3.5 3.0 2.5 2.0 1.5 TYPICAL MAX 1.0 MIN 0.5 0 0 1 2 3 7 4 5 6 8 DIFFERENTIAL PRESSURE (kPa) 9 10 11 Figure 4. Output versus Pressure Differential Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-99 Freescale Semiconductor, Inc. MPX5010 MPXV5010G SERIES Transfer Function (MPX5010, MPXV5010G) Nominal Transfer Value: Vout = VS x (0.09 x P + 0.04) Nominal Transfer Value: (Pressure Error x Temp. Factor x 0.09 x VS) Nominal Transfer Value: VS = 5.0 V 0.25 Vdc Temperature Error Band MPX5010, MPXV5010G Series 4.0 Freescale Semiconductor, Inc... 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band 0.5 0.4 0.3 Pressure Error (kPa) 0.2 0.1 0 -0.1 -0.2 0 1 2 3 4 5 6 7 8 9 10 Pressure (kPa) -0.3 -0.4 -0.5 3-100 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Pressure Error (Max) 0 to 10 kPa 0.5 kPa Motorola Sensor Device Data Freescale Semiconductor, MPX5010 Inc. MPXV5010G SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluoro silicone gel which protects the die from harsh media. The Motorola MPX Freescale Semiconductor, Inc... Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX5010D 867C Stainless Steel Cap MPX5010DP 867C Side with Part Marking MPX5010GP 867B Side with Port Attached MPX5010GS 867E Side with Port Attached MPX5010GSX 867F Side with Port Attached MPXV5010G6U 482 Stainless Steel Cap MPXV5010G7U 482B Stainless Steel Cap MPXV5010GC6U/T1 482A Side with Port Attached MPXV5010GC7U 482C Side with Port Attached MPXV5010GP 1369 Side with Port Attached MPXV5010DP 1351 Side with Part Marking ORDERING INFORMATION -- UNIBODY PACKAGE (MPX5010 SERIES) MPX Series Device Type Options Order Number Case Type Device Marking Basic Element Differential 867 MPX5010D MPX5010D Ported Elements Differential, Dual Port 867C MPX5010DP MPX5010DP Gauge 867B MPX5010GP MPX5010GP Gauge, Axial 867E MPX5010GS MPX5010D Gauge, Axial PC Mount 867F MPX5010GSX MPX5010D ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV5010G SERIES) Device Type Options Case No. Basic Elements Gauge, Element Only, SMT 482 MPXV5010G6U Rails MPXV5010G Gauge, Element Only, DIP 482B MPXV5010G7U Rails MPXV5010G Gauge, Axial Port, SMT 482A MPXV5010GC6U Rails MPXV5010G Gauge, Axial Port, DIP 482C MPXV5010GC7U Rails MPXV5010G Gauge, Axial Port, SMT 482A MPXV5010GC6T1 Tape and Reel MPXV5010G Gauge, Side Port, SMT 1369 MPXV5010GP Trays MPXV5010G Differential, Dual Port, SMT 1351 MPXV5010DP Trays MPXV5010G Ported Elements Motorola Sensor Device Data MPX Series Order No. Packing Options www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Marking 3-101 Freescale Semiconductor, Inc. MPX5010 MPXV5010G SERIES MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct footprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) 3-102 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA MPX5050 Integrated Silicon Pressure Sensor MPXV5050G On-Chip Signal Conditioned, Temperature Compensated SERIES and Calibrated Motorola Preferred Device The MPX5050/MPXV5050G series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 50 kPa (0 to 7.25 psi) 0.2 to 4.7 Volts Output Freescale Semiconductor, Inc... Features UNIBODY PACKAGE * 2.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Temperature Compensated Over - 40 to +125C * Patented Silicon Shear Stress Strain Gauge * Durable Epoxy Unibody Element * Easy-to-Use Chip Carrier Option MPX5050D CASE 867 VS SMALL OUTLINE PACKAGE SURFACE MOUNT THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GND GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5, AND 6 ARE NO CONNECTS FOR UNIBODY DEVICE PINS 1, 5, 6, 7, AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE MPX5050GP CASE 867B MPXV5050GP CASE 1369 Figure 1. Fully Integrated Pressure Sensor Schematic MPXV5050DP CASE 1351 MPX5050DP CASE 867C PIN NUMBER 1 N/C 5 N/C 2 6 N/C 3 VS Gnd 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. PIN NUMBER 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 6 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-103 Freescale Semiconductor, Inc. MPX5050 MPXV5050G SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Symbol Freescale Semiconductor, Inc... Characteristic Min Pressure Range(1) POP 0 Supply Voltage(2) VS 4.75 Supply Current Io -- Typ Max Unit -- 50 kPa 5.0 5.25 Vdc 7.0 10.0 mAdc Minimum Pressure Offset(3) @ VS = 5.0 Volts (0 to 85C) Voff 0.088 0.20 0.313 Vdc Full Scale Output(4) @ VS = 5.0 Volts (0 to 85C) VFSO 4.587 4.70 4.813 Vdc Full Scale Span(5) @ VS = 5.0 Volts (0 to 85C) VFSS -- 4.50 -- Vdc -- -- -- "2.5 %VFSS V/P -- 90 -- mV/kPa Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- -- %VFSS Accuracy(6) Sensitivity "0.5 NOTES: 1. 1.0kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Typ Unit Weight, Basic Element (Case 867) 4.0 grams Weight, Basic Element (Case 1369) 1.5 grams 3-104 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, MPX5050 Inc. MPXV5050G SERIES Figure 3 illustrates the Differential/Gauge Sensing Chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX5050/MPXV5050G series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 2 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. OUTPUT (V) Freescale Semiconductor, Inc... 5.0 TRANSFER FUNCTION: 4.5 Vout = VS*(0.018*P+0.04) ERROR 4.0 VS = 5.0 Vdc TEMP = 0 to 85C 3.5 3.0 TYPICAL 2.5 2.0 1.5 MIN MAX 1.0 0.5 0 0 5 10 15 35 40 20 25 30 DIFFERENTIAL PRESSURE (kPa) 45 50 55 Figure 2. Output versus Pressure Differential +5 V FLUORO SILICONE GEL DIE COAT STAINLESS STEEL METAL COVER DIE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE P1 Vout EPOXY PLASTIC CASE WIRE BOND LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT DIE BOND OUTPUT Vs IPS m 1.0 F m 0.01 F GND 470 pF P2 Figure 3. Cross-Sectional Diagram (Not to Scale) Motorola Sensor Device Data Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-105 Freescale Semiconductor, Inc. MPX5050 MPXV5050G SERIES Transfer Function Nominal Transfer Value: Vout = VS (P x 0.018 + 0.04) +/- (Pressure Error x Temp. Factor x 0.018 x VS) VS = 5.0 V 0.25 Vdc Temperature Error Band MPX5050/MPXV5050G Series 4.0 Temp 3.0 - 40 0 to 85 +125 2.0 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... Temperature Error Factor Multiplier 1.0 0.0 Pressure (in kPa) 0 10 20 30 40 50 60 -1.0 - 2.0 - 3.0 3-106 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Pressure Error (Max) 0 to 50 kPa 1.25 kPa Motorola Sensor Device Data Freescale Semiconductor, MPX5050 Inc. MPXV5050G SERIES PRESSURE (P1) / VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluorosilicone gel which protects the die from harsh media. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX5050D 867 Stainless Steel Cap MPX5050DP 867C Side with Part Marking MPX5050GP 867B Side with Port Attached MPXV5050GP 1369 Side with Port Attached MPXV5050DP 1351 Side with Part Marking Freescale Semiconductor, Inc... ORDERING INFORMATION -- UNIBODY PACKAGE (MPX5050 SERIES) MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Differential 867 MPX5050D MPX5050D Ported Elements Differential Dual Ports 867C MPX5050DP MPX5050DP Gauge 867B MPX5050GP MPX5050GP ORDERING INFORMATION -- SMALL OUTLINE PACKAGE (MPXV5050G SERIES) Device Type Ported Elements Options Case No. MPX Series Order No. Packing Options Marking Side Port 1369 MPXV5050GP Trays MPXV5050G Dual Port 1351 MPXV5050DP Trays MPXV5050G Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-107 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX5100 On-Chip Signal Conditioned, SERIES Temperature Compensated and Calibrated The MPX5100 series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. Freescale Semiconductor, Inc... Features INTEGRATED PRESSURE SENSOR 0 to 100 kPa (0 to 14.5 psi) 15 to 115 kPa (2.18 to 16.68 psi) 0.2 to 4.7 Volts Output * 2.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Patented Silicon Shear Stress Strain Gauge * Available in Absolute, Differential and Gauge Configurations * Durable Epoxy Unibody Element * Easy-to-Use Chip Carrier Option MPX5100D CASE 867 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5 AND 6 ARE NO CONNECTS MPX5100DP CASE 867C GND Figure 1. Fully Integrated Pressure Sensor Schematic MPX5100GSX CASE 867F PIN NUMBER 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 7 3-108 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5100 SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Characteristic Pressure Range(1) Gauge, Differential: MPX5100D Absolute: MPX5100A Supply Voltage(2) Freescale Semiconductor, Inc... Supply Current Minimum Pressure Offset(3) @ VS = 5.0 Volts (0 to 85C) Symbol Min Typ Max Unit POP 0 15 -- -- 100 115 kPa VS 4.75 5.0 5.25 Vdc Io -- 7.0 10 mAdc Voff 0.088 0.20 0.313 Vdc Full Scale Output(4) @ VS = 5.0 Volts Differential and Absolute (0 to 85C) Vacuum(10) VFSO 4.587 3.688 4.700 3.800 4.813 3.913 Vdc Full Scale Span(5) @ VS = 5.0 Volts Differential and Absolute (0 to 85C) Vacuum(10) VFSS -- -- 4.500 3.600 -- -- Vdc -- -- -- "2.5 %VFSS mV/kPa Accuracy(6) Sensitivity V/P -- 45 -- Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- -- %VFSS "0.5 NOTES: 1. 1.0kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) Motorola Sensor Device Data Typ Unit 4.0 grams www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-109 Freescale Semiconductor, Inc. MPX5100 SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION and SIGNAL CONDITIONING 5 VS = 5 Vdc TA = 25C MPX5100 4 MAX TYP SPAN RANGE (TYP) 3.5 3 2.5 OUTPUT RANGE (TYP) 4.5 OUTPUT (V) Figure 2 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. MIN 2 1.5 1 110 100 90 80 70 60 50 40 30 20 10 0 0 0.5 OFFSET (TYP) Freescale Semiconductor, Inc... PRESSURE (kPa) Figure 2. Output versus Pressure Differential EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE FLUORO SILICONE GEL DIE COAT EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE STAINLESS STEEL METAL COVER EPOXY PLASTIC CASE DIE WIRE BOND LEAD FRAME DIFFERENTIAL/GAUGE ELEMENT FLUORO SILICONE GEL DIE COAT STAINLESS STEEL METAL COVER EPOXY PLASTIC CASE DIE WIRE BOND LEAD FRAME DIE BOND ABSOLUTE ELEMENT DIE BOND Figure 3. Cross-Sectional Diagrams (Not to Scale) Figure 3 illustrates both the Differential/Gauge and the Absolute Sensing Chip in the basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The MPX5100 series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. +5 V Vout OUTPUT Vs IPS m 1.0 F m 0.01 F GND 470 pF Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. 3-110 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5100 SERIES Transfer Function (MPX5100D, MPX5100G) Nominal Transfer Value: Vout = VS (P x 0.009 + 0.04) +/- (Pressure Error x Temp. Mult. x 0.009 x VS) VS = 5.0 V 5% P kPa Temperature Error Multiplier Break Points MPX5100D Series 4.0 3.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 130 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Error (kPa) Freescale Semiconductor, Inc... 2.0 1.0 0.0 0 20 40 60 80 100 120 Pressure in kPa -1.0 -2.0 MPX5100D Series -3.0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Pressure Error (max) 0 to 100 kPa 2.5 kPa 3-111 Freescale Semiconductor, Inc. MPX5100 SERIES Transfer Function (MPX5100A) Nominal Transfer Value: Vout = VS (P x 0.009 - 0.095) +/- (Pressure Error x Temp. Mult. x 0.009 x VS) VS = 5.0 V 5% P kPa Temperature Error Multiplier Break Points Series MPX5100A Temp 4.0 Multiplier - 40 0 to 85 +125 3.0 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 130 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Error (kPa) Freescale Semiconductor, Inc... 2.0 1.0 0.0 0 20 40 60 80 100 130 Pressure in kPa -1.0 -2.0 MPX5100A Series -3.0 Pressure Error (max) 15 to 115 kPa 2.5 kPa 3-112 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5100 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluoro silicone gel which protects the die from harsh media. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the Table below: Pressure (P1) Side Identifier Case Type MPX5100A, MPX5100D 867 Stainless Steel Cap MPX5100DP 867C Side with Part Marking MPX5100AP, MPX5100GP 867B Side with Port Attached MPX5100GSX 867F Side with Port Attached Freescale Semiconductor, Inc... ORDERING INFORMATION: The MPX5100 pressure sensor is available in absolute, differential, and gauge configurations. Devices are available in the basic element package or with pressure port fittings that provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Name Basic Element Ported Elements Motorola Sensor Device Data Options Case Type Order Number Device Marking Absolute 867 MPX5100A MPX5100A Differential 867 MPX5100D MPX5100D Differential Dual Ports 867C MPX5100DP MPX5100DP Absolute, Single Port 867B MPX5100AP MPX5100AP Gauge, Single Port 867B MPX5100GP MPX5100GP Gauge, Axial PC Mount 867F MPX5100GSX MPX5100D www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-113 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 50 kPa Uncompensated Silicon Pressure Sensors MPX53 MPXV53GC SERIES The MPX53/MPXV53GC series silicon piezoresistive pressure sensors provide a very accurate and linear voltage output -- directly proportional to the applied pressure. These standard, low cost, uncompensated sensors permit manufacturers to design and add their own external temperature compensating and signal conditioning networks. Compensation techniques are simplified because of the predictability of Motorola's single element strain gauge design. 0 to 50 kPa (0 - 7.25 psi) 60 mV FULL SCALE SPAN (TYPICAL) Features * Low Cost * Patented Silicon Shear Stress Strain Gauge Design Freescale Semiconductor, Inc... * Ratiometric to Supply Voltage * Easy to Use Chip Carrier Package Options SMALL OUTLINE PACKAGE UNIBODY PACKAGE MPXV53GC6U CASE 482A MPX53D CASE 344 * 60 mV Span (Typ) * Differential and Gauge Options Application Examples * Air Movement Control * Environmental Control Systems * Level Indicators * Leak Detection * Medical Instrumentation * Industrial Controls * Pneumatic Control Systems * Robotics Figure 1 shows a schematic of the internal circuitry on the stand-alone pressure sensor chip. MPXV53GC7U CASE 482C + VS MPX53GP CASE 344B NOTE: Pin 1 is the notched pin. + Vout PIN NUMBER Sensor - Vout GND 1 Gnd 5 N/C 2 +Vout VS 6 N/C 3 7 N/C 4 -Vout 8 N/C Figure 1. Uncompensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). MPX53DP CASE 344C NOTE: Pin 1 is the notched pin. Replaces MPX50/D PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout REV 2 3-114 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX53 MPXV53GC SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 3.0 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 50 kPa Supply Voltage(2) VS -- 3.0 6.0 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 45 60 90 mV Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) Voff 0 20 35 mV Sensitivity V/P -- 1.2 -- mV/kPa Linearity(5) -- - 0.6 -- 0.4 %VFSS Pressure Hysteresis(5) (0 to 50 kPa) -- -- 0.1 -- %VFSS Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.5 -- %VFSS Temperature Coefficient of Full Scale Span(5) TCVFSS - 0.22 -- - 0.16 %VFSS/C TCVoff -- 15 -- V/C TCR 0.31 -- 0.37 %Zin/C Zin 355 -- 505 Temperature Coefficient of Offset(5) Temperature Coefficient of Resistance(5) Input Impedance Zout 750 -- 1875 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * TCR: Zin deviation with minimum rated pressure applied, over the temperature range of - 40C to +125C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-115 or by designing your system using the MPX2053 series sensors. Several approaches to external temperature compensation over both - 40 to +125C and 0 to + 80C ranges are presented in Motorola Applications Note AN840. TEMPERATURE COMPENSATION Figure 2 shows the typical output characteristics of the MPX53/MPXV53GC series over temperature. The piezoresistive pressure sensor element is a semiconductor device which gives an electrical output signal proportional to the pressure applied to the device. This device uses a unique transverse voltage diffused semiconductor strain gauge which is sensitive to stresses produced in a thin silicon diaphragm by the applied pressure. Because this strain gauge is an integral part of the silicon diaphragm, there are no temperature effects due to differences in the thermal expansion of the strain gauge and the diaphragm, as are often encountered in bonded strain gauge pressure sensors. However, the properties of the strain gauge itself are temperature dependent, requiring that the device be temperature compensated if it is to be used over an extensive temperature range. Temperature compensation and offset calibration can be achieved rather simply with additional resistive components, LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range (see Figure 3). There are two basic methods for calculating nonlinearity: (1) end point straight line fit or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. 70 100 LINEARITY 60 90 70 - 40C + 25C 50 60 OUTPUT (mVdc) MPX53 VS = 3 Vdc P1 > P2 80 OUTPUT (mVdc) Freescale Semiconductor, Inc... MPX53 MPXV53GC SERIESFreescale Semiconductor, Inc. SPAN RANGE (TYP) + 125C 50 40 30 ACTUAL 40 SPAN (VFSS) 30 THEORETICAL 20 20 OFFSET (TYP) 10 0 PSI 0 kPa 0 1 2 10 3 20 4 5 30 6 40 7 10 OFFSET (VOFF) 0 8 0 50 MAX PRESSURE (kPA) PRESSURE DIFFERENTIAL Figure 2. Output versus Pressure Differential SILICONE DIE COAT Figure 3. Linearity Specification Comparison STAINLESS STEEL METAL COVER EPOXY CASE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE DIE P1 WIRE BOND POP LEAD FRAME P2 RTV DIE BOND Figure 4. Cross-Sectional Diagram (not to scale) Figure 4 illustrates the differential or gauge configuration in the unibody chip carrier (Case 344). A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPX53/MPXV53GC series pressure sensor operating 3-116 characteristics and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long term reliability. Contact the factory for information regarding media compatibility in your application. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX53 MPXV53GC SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola presPart Number Case Type Pressure (P1) Side Identifier MPX53D 344 Stainless Steel Cap MPX53DP 344C Side with Port Marking MPX53GP 344B Side with Port Attached 482A, 482C Sides with Port Attached MPXV53GC series Freescale Semiconductor, Inc... sure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: ORDERING INFORMATION - UNIBODY PACKAGE MPX53 series pressure sensors are available in differential and gauge configurations. Devices are available with basic element package or with pressure port fittings which provide printed circuit board mounting ease and barbed hose pressure connections. MPX Series Device Type Options Case Type Order Number Device Marking Basic Element Differential Case 344 MPX53D MPX53D Ported Elements Differential Case 344C MPX53DP MPX53DP Gauge Case 344B MPX53GP MPX53GP ORDERING INFORMATION -- SMALL OUTLINE PACKAGE The MPXV53GC series pressure sensors are available with a pressure port, surface mount or DIP leadforms, and two packing options. Device Order No. Case No. Packing Options 482A Tape & Rail MPXV53G MPXV53GC6U 482A Rails MPXV53G MPXV53GC7U 482C Rails MPXV53G MPXV53GC6T1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Marking 3-117 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX5500 On-Chip Signal Conditioned, SERIES Temperature Compensated and Calibrated The MPX5500 series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 500 kPa (0 to 72.5 psi) 0.2 to 4.7 Volts Output Freescale Semiconductor, Inc... Features * 2.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Patented Silicon Shear Stress Strain Gauge * Durable Epoxy Unibody Element * Available in Differential and Gauge Configurations MPX5500D CASE 867 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5 AND 6 ARE NO CONNECTS MPX5500DP CASE 867C GND Figure 1. Fully Integrated Pressure Sensor Schematic PIN NUMBER 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 5 3-118 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5500 SERIES MAXIMUM RATINGS(1) Parametrics Maximum Pressure(2) (P2 v 1 Atmosphere) Storage Temperature Operating Temperature Symbol Value Unit P1max 2000 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTES: 1. Maximum Ratings apply to Case 867 only. Extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. This sensor is designed for applications where P1 is always greater than, or equal to P2. P2 maximum is 500 kPa. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Freescale Semiconductor, Inc... Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 500 kPa Supply Voltage(2) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 7.0 10.0 mAdc Zero Pressure Offset(3) (0 to 85C) Voff 0.088 0.20 0.313 Vdc Full Scale Output(4) (0 to 85C) VFSO 4.587 4.70 4.813 Vdc Full Scale Span(5) (0 to 85C) VFSS -- 4.50 -- Vdc -- -- -- "2.5 %VFSS V/P -- 9.0 -- mV/kPa Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Accuracy(6) Sensitivity NOTES: 1. 1.0kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) Motorola Sensor Device Data Typ Unit 4.0 grams www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-119 Freescale Semiconductor, Inc. MPX5500 SERIES Figure 3 illustrates the Differential/Gauge basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. (For use of the MPX5500D in a high pressure, cyclic application, consult the factory.) The MPX5500 series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 2 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. OUTPUT (V) Freescale Semiconductor, Inc... 5.0 TRANSFER FUNCTION: 4.5 Vout = VS*(0.0018*P+0.04) ERROR 4.0 VS = 5.0 Vdc TEMP = 0 to 85C 3.5 3.0 TYPICAL 2.5 2.0 MAX MIN 1.5 1.0 0.5 0 0 50 100 150 200 250 300 350 400 DIFFERENTIAL PRESSURE (kPa) 450 500 550 Figure 2. Output versus Pressure Differential FLUORO SILICONE DIE COAT DIE +5 V STAINLESS STEEL METAL COVER EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE P1 Vout Vs WIRE BOND LEAD FRAME RTV DIE BOND P2 OUTPUT IPS m 1.0 F m 0.01 F GND 470 pF EPOXY CASE Figure 3. Cross-Sectional Diagram (Not to Scale) 3-120 Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5500 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluorosilicone gel which protects the die from the environment. The Motorola Part Number MPX pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the Table below: Pressure (P1) Side Identifier Case Type MPX5500D 867 Stainless Steel Cap MPX5500DP 867C Side with Part Marking ORDERING INFORMATION Freescale Semiconductor, Inc... MPX Series Device Name Options Case Type Order Number Device Marking Basic Element Differential 867 MPX5500D MPX5500D Ported Elements Differential Dual Ports 867C MPX5500DP MPX5500DP Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-121 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPX5700 On-Chip Signal Conditioned, SERIES Temperature Compensated and Calibrated The MPX5700 series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 700 kPa (0 to 101.5 psi) 15 to 700 kPa (2.18 to 101.5 psi) 0.2 to 4.7 V OUTPUT Freescale Semiconductor, Inc... Features * 2.5% Maximum Error over 0 to 85C * Ideally Suited for Microprocessor or Microcontroller-Based Systems * Available in Absolute, Differential and Gauge Configurations * Patented Silicon Shear Stress Strain Gauge * Durable Epoxy Unibody Element MPX5700D CASE 867 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 4, 5 AND 6 ARE NO CONNECTS MPX5700DP CASE 867C GND Figure 1. Fully Integrated Pressure Sensor Schematic MPX5700AS CASE 867E PIN NUMBER 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 5 3-122 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5700 SERIES MAXIMUM RATINGS(1) Parametrics Maximum Pressure(2) (P2 v 1 Atmosphere) Storage Temperature Symbol Value Unit P1max 2800 kPa Tstg - 40 to +125 C TA - 40 to +125 C Operating Temperature NOTES: 1. Maximum Ratings apply to Case 867 only. Extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. This sensor is designed for applications where P1 is always greater than, or equal to P2. P2 maximum is 500 kPa. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Symbol Min Typ Max Unit POP 0 15 -- 700 700 kPa Supply Voltage(2) VS 4.75 5.0 5.25 Vdc Supply Current Io - 7.0 10 mAdc Voff 0.088 0.184 0.2 0.313 0.409 Vdc Characteristic Freescale Semiconductor, Inc... Pressure Range(1) Gauge, Differential: MPX5700D Absolute: MPX5700A Zero Pressure Offset(3) Gauge, Differential: Absolute (0 to 85C) (0 to 85C) Full Scale Output(4) (0 to 85C) VFSO 4.587 4.7 4.813 Vdc Full Scale Span(5) (0 to 85C) VFSS -- 4.5 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 2.5 %VFSS V/P -- 6.4 -- mV/kPa tR -- 1.0 -- ms IO+ -- 0.1 -- mAdc -- -- 20 -- ms Sensitivity Response Time(7) Output Source Current at Full Scale Output Warm-Up Time(8) NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) Motorola Sensor Device Data Typ Unit 4.0 grams www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-123 Freescale Semiconductor, Inc. MPX5700 SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING Figure 3 illustrates the Differential/Gauge basic chip carrier (Case 867). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. (For use of the MPX5700D in a high pressure, cyclic application, consult the factory.) The MPX5700 series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 2 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. TRANSFER FUNCTION: Vout = VS*(0.0012858*P+0.04) ERROR 4.0 VS = 5.0 Vdc TEMP = 0 to 85C 3.5 4.5 OUTPUT (V) Freescale Semiconductor, Inc... 5.0 3.0 TYPICAL 2.5 2.0 MIN MAX 1.5 1.0 0.5 0 0 100 300 500 200 400 600 DIFFERENTIAL PRESSURE (kPa) 700 800 Figure 2. Output versus Pressure Differential FLUORO SILICONE DIE COAT +5 V STAINLESS STEEL METAL COVER DIE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE P1 WIRE BOND LEAD FRAME RTV DIE BOND P2 Vout OUTPUT Vs IPS m 1.0 F m 0.01 F GND 470 pF EPOXY CASE Figure 3. Cross-Sectional Diagram (Not to Scale) 3-124 Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5700 SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluoro silicone gel which protects the die from harsh media. The Motorola MPX Freescale Semiconductor, Inc... Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX5700D, MPX5700A 867C Stainless Steel Cap MPX5700DP 867C Side with Part Marking MPX5700GP, MPX5700AP 867B Side with Port Attached MPX5700GS, MPX5700AS 867E Side with Port Attached ORDERING INFORMATION MPX Series Device Type Basic Element Ported Elements Options Case Type Order Number Device Marking Differential 867C MPX5700D MPX5700D Absolute 867C MPX5700A MPX5700A Differential Dual Ports 867C MPX5700DP MPX5700DP Gauge 867B MPX5700GP MPX5700GP Gauge, Axial 867E MPX5700GS MPX5700D Absolute 867B MPX5700AP MPX5700AP Absolute, Axial 867E MPX5700AS MPX5700A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-125 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPX5999D Temperature Compensated Freescale Semiconductor, Inc... and Calibrated The MPX5999D piezoresistive transducer is a state-of-the-art pressure sensor designed for a wide range of applications, but particularly for those employing a microcontroller or microprocessor with A/D inputs. This patented, single element transducer combines advanced micromachining techniques, thin-film metallization and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on the stand-alone sensing chip. INTEGRATED PRESSURE SENSOR 0 to 1000 kPa (0 to 150 psi) 0.2 to 4.7 V OUTPUT Features * Temperature Compensated Over 0 to 85C * Ideally Suited for Microprocessor or Microcontroller-Based Systems * Patented Silicon Shear Stress Strain Gauge * Durable Epoxy Unibody Element MPX5999D CASE 867 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY PIN NUMBER Vout PINS 4, 5 AND 6 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic 1 Vout 4 N/C 2 Gnd 5 N/C 3 VS 6 N/C NOTE: Pins 4, 5, and 6 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 4 3-126 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5999D MAXIMUM RATINGS(1) Parametrics Maximum Pressure(2) (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit P1max 4000 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTES: 1. Extended exposure at the specified limits may cause permanent damage or degradation to the device. 2. This sensor is designed for applications where P1 is always greater than, or equal to P2. P2 maximum is 500 kPa. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 4 required to meet electrical specifications.) Freescale Semiconductor, Inc... Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 1000 kPa Supply Voltage(2) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 7.0 10 mAdc Zero Pressure Offset(3) Voff 0.088 0.2 0.313 Vdc Full Scale Output(4) (0 to 85C) (0 to 85C) VFSO 4.587 4.7 4.813 Vdc Full Scale Span(5) (0 to 85C) VFSS -- 4.5 -- Vdc V/P -- 4.5 -- mV/kPa -- -- -- 2.5 %VFSS tR -- 1.0 -- ms IO+ -- 0.1 -- mA -- -- 20 -- ms Sensitivity Accuracy(6) (0 to 85C) Response Time(7) Output Source Current at Full Scale Output Warm-Up Time(8) NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the device to meet the specified output voltage after the pressure has been stabilized. MECHANICAL CHARACTERISTICS Characteristics Weight, Basic Element (Case 867) Motorola Sensor Device Data Typ Unit 4.0 grams www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-127 Freescale Semiconductor, Inc. MPX5999D ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING Figure 2 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 4. The output will saturate outside of the specified pressure range. The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip. Figure 3 illustrates the differential or gauge configuration in the basic chip carrier (Case 867). A fluoro silicone gel isolates the die surface and wire bonds from harsh environments, while al- lowing the pressure signal to be transmitted to the silicon diaphragm. The MPX5999D pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. Figure 4 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. OUTPUT (V) Freescale Semiconductor, Inc... 5.0 TRANSFER FUNCTION: 4.5 Vout = VS*(0.000901*P+0.04) ERROR 4.0 VS = 5.0 Vdc TEMP = 0 to 85C 3.5 3.0 TYPICAL 2.5 2.0 MAX MIN 1.5 1.0 0.5 0 0 100 200 300 400 500 600 700 800 DIFFERENTIAL PRESSURE (kPa) 900 1000 1100 Figure 2. Output versus Pressure Differential SILICONE DIE COAT +5 V STAINLESS STEEL METAL COVER EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE EEEEEEEEEEEE DIE P1 Vout LEAD FRAME RTV DIE BOND P2 THERMOPLASTIC CASE Figure 3. Cross-Sectional Diagram (Not to Scale) 3-128 OUTPUT Vs WIRE BOND IPS m 1.0 F m 0.01 F GND 470 pF Figure 4. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5999D PRESSURE (P1) / VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing fluoro silicone gel which protects the die from harsh media. The Motorola MPX Part Number pressure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Pressure (P1) Side Identifier Case Type MPX5999D 867 Stainless Steel Cap Freescale Semiconductor, Inc... ORDERING INFORMATION The MPX5999D pressure sensor is available as an element only. MPX Series Device Type Basic Element Options Differential Motorola Sensor Device Data Case Type 867 Order Number MPX5999D www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Device Marking MPX5999D 3-129 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA High Temperature Accuracy MPXA6115A Integrated Silicon Pressure Sensor MPXH6115A for Measuring Absolute Pressure, SERIES On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated INTEGRATED PRESSURE SENSOR 15 to 115 kPa (2.2 to 16.7 psi) 0.2 to 4.8 Volts Output Motorola's MPXA6115A/MPXH6115A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPXA6115A/MPXH6115A series piezoresistive transducer is a state-of-the-art, monolithic, signal SUPER SMALL OUTLINE conditioned, silicon pressure sensor. This sensor PACKAGE combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. MPXH6115A6U Features * Improved Accuracy at High Temperature * Available in Small and Super Small Outline Packages * 1.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Temperature Compensated from - 40 to +125C * Durable Thermoplastic (PPS) Surface Mount Package Application Examples * Aviation Altimeters * Industrial Controls * Engine Control/Manifold Absolute Pressure (MAP) * Weather Station and Weather Reporting Device Barometers THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT CASE 1317 MPXA6115A6U CASE 482 MPXH6115AC6U CASE 1317A MPXA6115AC6U CASE 482A PIN NUMBER PIN NUMBER 1 N/C 5 N/C 1 N/C 5 N/C 2 6 N/C 2 N/C 7 N/C 3 VS Gnd 6 3 VS Gnd 7 N/C 4 Vout 8 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the chamfered corner of the package. VS GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY SMALL OUTLINE PACKAGE NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the notch in the lead. Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic REV 1 3-130 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXA6115A MPXH6115A SERIES MAXIMUM RATINGS(1) Parametrics Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C Operating Temperature TA -40 to +125 C Output Source Current @ Full Scale Output(2) Io+ 0.5 mAdc Output Sink Current @ Minimum Pressure Offset(2) Io- -0.5 mAdc Maximum Pressure (P1 u P2) Storage Temperature NOTES: 1. Exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. Maximum Output Current is controlled by effective impedance from Vout to Gnd or Vout to VS in the application circuit. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 Characteristic Min Typ Max Unit POP 15 -- 115 kPa Supply Voltage(1) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 6.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2.) Symbol Minimum Pressure Offset(2) @ VS = 5.0 Volts (0 to 85C) Voff 0.133 0.200 0.268 Vdc Full Scale Output(3) @ VS = 5.0 Volts (0 to 85C) VFSO 4.633 4.700 4.768 Vdc Full Scale Span(4) @ VS = 5.0 Volts (0 to 85C) VFSS 4.433 4.500 4.568 Vdc Accuracy(5) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 45.9 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Warm-Up Time(7) -- -- 20 -- ms Offset Stability(8) -- -- 0.25 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-131 Freescale Semiconductor, Inc. MPXA6115A MPXH6115A SERIES DIE FLUORO SILICONE GEL DIE COAT +5.0 V STAINLESS STEEL CAP P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME VS Pin 2 MPXA6115A MPXH6115A Vout Pin 4 100 nF to ADC 47 pF GND Pin 3 51 K ABSOLUTE ELEMENT DIE BOND SEALED VACUUM REFERENCE Figure 2 illustrates the absolute sensing chip in the basic Super Small Outline chip carrier (Case 1317). Figure 3. Typical Application Circuit (Output Source Current Operation) Figure 3 shows a typical application circuit (output source current operation). 5.0 4.5 4.0 OUTPUT (Volts) 3.5 MAX TRANSFER FUNCTION: Vout = Vs* (.009*P-.095) Error VS = 5.0 Vdc TEMP = 0 to 85C TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SSOP (not to scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over 0 to 85C temperature range. The output will saturate outside of the rated pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The 3-132 MPXA6115A/MPXH6115A series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXA6115A MPXH6115A SERIES Transfer Function (MPXA6115A/MPXH6115A) Nominal Transfer Value: Vout = VS x (0.009 x P - 0.095) (Pressure Error x Temp. Factor x 0.009 x VS) VS = 5.0 0.25 Vdc Temperature Error Band MPXA6115A/MPXH6115A Series 4.0 Break Points Temp 3.0 Temperature Error Factor Multiplier - 40 0 to 85 125 2.0 3 1 1.75 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 Pressure Error (Max) 15 to 115 (kPa) 1.5 (kPa) ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXA6115A6U Rails MPXA6115A Absolute, Element Only 482 MPXA6115A6T1 Tape and Reel MPXA6115A Absolute, Axial Port 482A MPXA6115AC6U Rails MPXA6115A Absolute, Axial Port 482A MPXA6115AC6T1 Tape and Reel MPXA6115A Ported Element MPX Series Order No. Packing Options Marking ORDERING INFORMATION -- SUPER SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 1317 MPXH6115A6U Rails MPXH6115A Absolute, Element Only 1317 MPXH6115A6T1 Tape and Reel MPXH6115A Absolute, Axial Port 1317A MPXH6115AC6U Rails MPXH6115A Absolute, Axial Port 1317A MPXH6115AC6T1 Tape and Reel MPXH6115A Ported Element Motorola Sensor Device Data MPX Series Order No. Packing Options www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Marking 3-133 Freescale Semiconductor, Inc. MPXA6115A MPXH6115A SERIES SURFACE MOUNTING INFORMATION MINIMUM RECOMMENDED FOOTPRINT FOR SMALL AND SUPER SMALL PACKAGES a solder reflow process. It is always recommended to fabricate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. Surface mount board layout is a critical portion of the total design. The footprint for the semiconductor package must be the correct size to ensure proper solder connection interface between the board and the package. With the correct pad geometry, the packages will self-align when subjected to 0.100 TYP 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 inch mm 0.100 TYP 8X 2.54 Figure 5. SOP Footprint (Case 482) 0.050 1.27 TYP 0.387 9.83 0.150 3.81 0.027 TYP 8X 0.69 0.053 TYP 8X 1.35 inch mm Figure 6. SSOP Footprint (Case 1317 and 1317A) 3-134 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Media Resistant, Integrated Silicon Pressure Sensor for Manifold MPXAZ4100A SERIES Absolute Pressure Applications On-Chip Signal Conditioned, Temperature Compensated, and Freescale Semiconductor, Inc... Calibrated The Motorola MPXAZ4100A series Manifold Absolute Pressure (MAP) sensor for engine control is designed to sense absolute air pressure within the intake manifold. This measurement can be used to compute the amount of fuel required for each cylinder. The small form factor and high reliability of on-chip integration makes the Motorola MAP sensor a logical and economical choice for automotive system designers. The MPXAZ4100A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. INTEGRATED PRESSURE SENSOR 20 to 105 kPa (2.9 to 15.2 psi) 0.3 to 4.9 V Output SMALL OUTLINE PACKAGE MPXAZ4100AC6U CASE 482A Features * Resistant to high humidity and common automotive media * 1.8% Maximum Error Over 0 to 85C * Specifically Designed for Intake Manifold Absolute Pressure Sensing in Engine Control Systems * Ideally Suited for Microprocessor or Microcontroller Based Systems * Temperature Compensated Over - 40C to +125C MPXAZ4100A6U CASE 482 * Durable Thermoplastic (PPS) Surface Mount Package Application Examples PIN NUMBER * Manifold Sensing for Automotive Systems * Also Ideal for Non-Automotive Applications 1 N/C 5 N/C 2 VS Gnd 6 N/C 7 N/C 3 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT N/C Vout 8 NOTE: Pins 1, 5, 6, 7, and 8 are not device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. 4 GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND Figure 1. Fully Integrated Pressure Sensor Schematic Rev 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-135 Freescale Semiconductor, Inc. MPXAZ4100A SERIES MAXIMUM RATINGS(NOTE) Parametric Maximum Pressure (P1 > P2) Storage Temperature Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C TA - 40 to +125 C Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Freescale Semiconductor, Inc... Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 20 -- 105 kPa Supply Voltage(2) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Minimum Pressure Offset(3) @ VS = 5.1 Volts (0 to 85C) Voff 0.225 0.306 0.388 Vdc Full Scale Output(4) @ VS = 5.1 Volts (0 to 85C) VFSO 4.870 4.951 5.032 Vdc Full Scale Span(5) @ VS = 5.1 Volts (0 to 85C) VFSS -- 4.59 -- Vdc Accuracy(6) (0 to 85C) -- -- -- 1.8 %VFSS Sensitivity V/P -- 54 -- mV/kPa Response Time(7) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(8) -- -- 20 -- ms Offset Stability(9) -- -- 0.5 -- %VFSS NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 5. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 6. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 7. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 8. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized. 9. Offset Stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-136 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. FLUORO SILICONE GEL DIE COAT DIE MPXAZ4100A SERIES STAINLESS STEEL CAP P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME ABSOLUTE ELEMENT DIE BOND Figure 2. Cross Sectional Diagram SOP (not to scale) Figure 2 illustrates an absolute sensing chip in the basic chip carrier (Case 482). 5.0 4.5 +5 V 4.0 Vout OUTPUT Vs IPS m 1.0 F m 0.01 F GND OUTPUT (Volts) 3.5 3.0 TRANSFER FUNCTION: Vout = Vs* (.01059*P-.152) Error VS = 5.1 Vdc TEMP = 0 to 85C 20 kPa TO 105 kPa MPXAZ4100A MAX TYP 2.5 2.0 1.5 470 pF MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 Freescale Semiconductor, Inc... SEALED VACUUM REFERENCE Pressure (ref: to sealed vacuum) in kPa Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. A gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The gel die coat and durable polymer package provide a media resis- Motorola Sensor Device Data Figure 4. Output versus Absolute Pressure tant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments containing common automotive media. Contact the factory for more information regarding media compatibility in your specific application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-137 MPXAZ4100A SERIES Freescale Semiconductor, Inc. Transfer Function (MPXAZ4100A) Nominal Transfer Value: Vout = VS (P x 0.01059 - 0.1518) +/- (Pressure Error x Temp. Factor x 0.01059 x VS) VS = 5.1 V 0.25 Vdc Temperature Error Band MPXAZ4100A Series 4.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 1.0 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C. Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 3.0 1.0 0.0 20 40 60 80 100 Pressure (in kPa) 120 -1.0 - 2.0 - 3.0 Pressure Error (Max) 20 to 105 (kPa) 1.5 (kPa) ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXAZ4100A6U Rails MPXAZ4100A Absolute, Element Only 482 MPXAZ4100A6T1 Tape and Reel MPXAZ4100A Absolute, Axial Port 482A MPXAZ4100AC6U Rails MPXAZ4100A Absolute, Axial Port 482A MPXAZ4100AC6T1 Tape and Reel MPXAZ4100A Ported Element 3-138 MPX Series Order No. Packing Options For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXAZ4100A SERIES INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-139 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Media Resistant, Integrated Silicon Pressure Sensor for Manifold MPXAZ4115A SERIES Absolute Pressure, Altimeter or Barometer Applications On-Chip Signal Conditioned, Temperature Compensated, and Freescale Semiconductor, Inc... Calibrated INTEGRATED PRESSURE SENSOR 15 to 115 kPa (2.2 to 16.7 psi) 0.2 to 4.8 V Output Motorola's MPXAZ4115A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPXAZ4115A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. SMALL OUTLINE PACKAGE MPXAZ4115AC6U CASE 482A Features * Resistant to high humidity and common automotive media * 1.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller- Based Systems * Temperature Compensated from - 40 to +125C * Durable Thermoplastic (PPS) Surface Mount Package Application Examples MPXAZ4115A6U CASE 482 * Aviation Altimeters * Industrial Controls * Engine Control PIN NUMBER * Weather Stations and Weather Reporting Devices VS 1 N/C 5 N/C 2 VS Gnd 6 N/C 7 N/C 3 N/C Vout 8 NOTE: Pins 1, 5, 6, 7, and 8 are not device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. 4 THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND Figure 1. Fully Integrated Pressure Sensor Schematic Rev 0 3-140 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXAZ4115A SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 u P2) Storage Temperature Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C TA -40 to +125 C Operating Temperature NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 required to meet Electrical Specifications.) Characteristic Symbol Min Typ Max Unit POP 15 -- 115 kPa Supply Voltage(1) VS 4.85 5.1 5.35 Vdc Supply Current Io -- 7.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2. Decoupling circuit shown in Figure 3 Minimum Pressure Offset(2) @ VS = 5.1 Volts (0 to 85C) Voff 0.135 0.204 0.273 Vdc Full Scale Output(3) @ VS = 5.1 Volts (0 to 85C) VFSO 4.725 4.794 4.863 Vdc Full Scale Span(4) @ VS = 5.1 Volts (0 to 85C) VFSS 4.521 4.590 4.659 Vdc Accuracy(5) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 45.9 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io+ -- 0.1 -- mAdc Warm-Up Time(7) -- -- 20 -- ms Offset Stability(8) -- -- 0.5 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-141 Freescale Semiconductor, Inc. MPXAZ4115A SERIES FLUORO SILICONE GEL DIE COAT +5 V DIE STAINLESS STEEL CAP Vout P1 Vs WIRE BOND THERMOPLASTIC CASE LEAD FRAME IPS m 1.0 F ABSOLUTE ELEMENT m GND 0.01 F 470 pF DIE BOND Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. SEALED VACUUM REFERENCE Figure 2. Cross Sectional Diagram SOP (not to scale) Figure 2 illustrates the absolute sensing chip in the basic chip carrier (Case 482). Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. 5.0 4.5 4.0 OUTPUT (Volts) 3.5 MAX TRANSFER FUNCTION: Vout = Vs* (.009*P-.095) Error VS = 5.1 Vdc TEMP = 0 to 85C TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Freescale Semiconductor, Inc... OUTPUT Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over a temperature range of 0 to 85C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. A gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal 3-142 to be transmitted to the sensor diaphragm. The gel die coat and durable polymer package provide a media resistant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments containing common automotive media. Contact the factory for more information regarding media compatibility in your specific application. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXAZ4115A SERIES Transfer Function (MPXAZ4115A) Nominal Transfer Value: Vout = VS x (0.009 x P - 0.095) (Pressure Error x Temp. Factor x 0.009 x VS) VS = 5.1 0.25 Vdc Temperature Error Band MPXAZ4115A Series 4.0 Break Points 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 125 3 1 3 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 Pressure Error (Max) 15 to 115 (kPa) 1.5 (kPa) ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXAZ4115A6U Rails MPXAZ4115A Absolute, Element Only 482 MPXAZ4115A6T1 Tape and Reel MPXAZ4115A Absolute, Axial Port 482A MPXAZ4115AC6U Rails MPXAZ4115A Absolute, Axial Port 482A MPXAZ4115AC6T1 Tape and Reel MPXAZ4115A Ported Element Motorola Sensor Device Data MPX Series Order No. Packing Options www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Marking 3-143 MPXAZ4115A SERIES Freescale Semiconductor, Inc. INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 Freescale Semiconductor, Inc... 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) 3-144 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Media Resistant and High Temperature Accuracy MPXAZ6115A SERIES Integrated Silicon Pressure Sensor for Measuring Absolute Pressure, On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated INTEGRATED PRESSURE SENSOR 15 to 115 kPa (2.2 to 16.7 psi) 0.2 to 4.8 Volts Output Motorola's MPXAZ6115A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPXAZ6115A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. SMALL OUTLINE PACKAGE MPXAZ6115A6U CASE 482 Features * Resistant to High Humidity and Common Automotive Media * Improved Accuracy at High Temperature * 1.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Temperature Compensated from - 40 to +125C * Durable Thermoplastic (PPS) Surface Mount Package MPXAZ6115AC6U CASE 482A Application Examples * Aviation Altimeters PIN NUMBER * Industrial Controls * Engine Control/Manifold Absolute Pressure (MAP) * Weather Station and Weather Reporting Devices VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT 1 N/C 5 N/C 2 6 N/C 3 VS Gnd 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the notch in the lead. GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-145 MPXAZ6115A SERIES Freescale Semiconductor, Inc. MAXIMUM RATINGS(1) Parametrics Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C Operating Temperature TA -40 to +125 C Output Source Current @ Full Scale Output(2) Io+ 0.5 mAdc Output Sink Current @ Minimum Pressure Offset(2) Io- -0.5 mAdc Maximum Pressure (P1 u P2) Storage Temperature NOTES: 1. Exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. Maximum Output Current is controlled by effective impedance from Vout to Gnd or Vout to VS in the application circuit. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 Characteristic Min Typ Max Unit POP 15 -- 115 kPa Supply Voltage(1) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 6.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2.) Symbol Minimum Pressure Offset(2) @ VS = 5.0 Volts (0 to 85C) Voff 0.133 0.200 0.268 Vdc Full Scale Output(3) @ VS = 5.0 Volts (0 to 85C) VFSO 4.633 4.700 4.768 Vdc Full Scale Span(4) @ VS = 5.0 Volts (0 to 85C) VFSS 4.433 4.500 4.568 Vdc Accuracy(5) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 45.9 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Warm-Up Time(7) -- -- 20 -- ms Offset Stability(8) -- -- 0.25 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. 3-146 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. FLUORO SILICONE GEL DIE COAT DIE MPXAZ6115A SERIES STAINLESS STEEL CAP P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME +5.0 V ABSOLUTE ELEMENT VS Pin 2 DIE BOND MPXAZ6115A SEALED VACUUM REFERENCE 100 nF Vout Pin 4 to ADC 47 pF GND Pin 3 51 K Figure 3. Typical Application Circuit (Output Source Current Operation) Figure 2 illustrates the absolute sensing chip in the basic Small Outline chip carrier (Case 482). Figure 3 shows a typical application circuit (output source current operation). 5.0 4.5 4.0 OUTPUT (Volts) 3.5 MAX TRANSFER FUNCTION: Vout = Vs* (.009*P-.095) Error VS = 5.0 Vdc TEMP = 0 to 85C TYP 3.0 2.5 2.0 1.5 MIN 1.0 0.5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SOP (Not to Scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over 0 to 85C temperature range. The output will saturate outside of the rated pressure range. A gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm. The gel die Motorola Sensor Device Data coat and durable polymer package provide a media resistant barrier that allows the sensor to operate reliably in high humidity conditions as well as environments containing common automotive media. Contact the factory for more information regarding media compatibility in your specific application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-147 MPXAZ6115A SERIES Freescale Semiconductor, Inc. Transfer Function (MPXAZ6115A) Nominal Transfer Value: Vout = VS x (0.009 x P - 0.095) (Pressure Error x Temp. Factor x 0.009 x VS) VS = 5.0 0.25 Vdc Temperature Error Band MPXAZ6115A Series 4.0 Break Points Temp 3.0 Temperature Error Factor Multiplier - 40 0 to 85 125 2.0 3 1 1.75 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 3.0 2.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 1.0 0.0 20 40 60 80 100 120 Pressure (in kPa) -1.0 - 2.0 - 3.0 Pressure Error (Max) 15 to 115 (kPa) 1.5 (kPa) ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 482 MPXAZ6115A6U Rails MPXAZ6115A Absolute, Element Only 482 MPXAZ6115A6T1 Tape and Reel MPXAZ6115A Absolute, Axial Port 482A MPXAZ6115AC6U Rails MPXAZ6115A Absolute, Axial Port 482A MPXAZ6115AC6T1 Tape and Reel MPXAZ6115A Ported Element 3-148 MPX Series Order No. Packing Options For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXAZ6115A SERIES SURFACE MOUNTING INFORMATION MINIMUM RECOMMENDED FOOTPRINT FOR SMALL OUTLINE PACKAGE Surface mount board layout is a critical portion of the total design. The footprint for the semiconductor package must be the correct size to ensure proper solder connection interface between the board and the package. With the correct pad geometry, the packages will self-align when subjected to a solder reflow process. It is always recommended to fabricate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.100 TYP 2.54 Freescale Semiconductor, Inc... 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm Figure 5. SOP Footprint (Case 482 and 482A) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-149 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA High Volume Sensor for Low Pressure Applications Motorola has developed a low cost, high volume, miniature pressure sensor package which is ideal as a sub-module component or a disposable unit. The unique concept of the Chip Pak allows great flexibility in system design while allowing an economic solution for the designer. This new chip carrier package uses Motorola's unique sensor die with its piezoresistive technology, along with the added feature of on-chip, thin-film temperature compensation and calibration. NOTE: Motorola is also offering the Chip Pak package in application-specific configurations, which will have an "SPX" prefix, followed by a four-digit number, unique to the specific customer. MPXC2011DT1 MPXC2012DT1 Motorola Preferred Device PRESSURE SENSORS 0 to 75 mmHg (0 to 10 kPa) Freescale Semiconductor, Inc... Features: * Low Cost CHIP PAK PACKAGE * Integrated Temperature Compensation and Calibration * Ratiometric to Supply Voltage * Polysulfone Case Material (Medical, Class V Approved) * Provided in Easy-to-Use Tape and Reel MPXC2011DT1/MPXC2012DT1 CASE 423A Application Examples * Respiratory Diagnostics * Air Movement Control * Controllers PIN NUMBER * Pressure Switching 1 Gnd 3 VS NOTE: The die and wire bonds are exposed on the front side of the Chip Pak (pressure is applied to the backside of the device). Front side die and wire protection must be provided in the customer's housing. Use caution when handling the devices during all processes. 2 S+ 4 S- Motorola's MPXC2011DT1/MPXC2012DT1 Pressure Sensor has been designed for medical usage by combining the performance of Motorola's shear stress pressure sensor design and the use of biomedically approved materials. Materials with a proven history in medical situations have been chosen to provide a sensor that can be used with confidence in applications, such as invasive blood pressure monitoring. It can be sterilized using ethylene oxide. The portions of the pressure sensor that are required to be biomedically approved are the rigid housing and the gel coating. The rigid housing is molded from a white, medical grade polysulfone that has passed extensive biological testing including: tissue culture test, rabbit implant, hemolysis, intracutaneous test in rabbits, and system toxicity, USP. The MPXC2011DT1 contains a silicone dielectric gel which covers the silicon piezoresistive sensing element. The gel is a nontoxic, nonallergenic elastomer system which meets all USP XX Biological Testing Class V requirements. The properties of the gel allow it to transmit pressure uniformly to the diaphragm surface, while isolating the internal electrical connections from the corrosive effects of fluids, such as saline solution. The gel provides electrical isolation sufficient to withstand defibrillation testing, as specified in the proposed Association for the Advancement of Medical Instrumentation (AAMI) Standard for blood pressure transducers. A biomedically approved opaque filler in the gel prevents bright operating room lights from affecting the performance of the sensor. The MPXC2012DT1 is a no-gel option. Preferred devices are Motorola recommended choices for future use and best overall value. REV 2 3-150 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXC2011DT1 MPXC2012DT1 MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (Backside) Storage Temperature Operating Temperature Symbol Value Unit Pmax 75 kPa Tstg - 25 to +85 C TA +15 to +40 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 10 kPa Supply Voltage(2) VS -- 3 10 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 24 25 26 mV Voff -1.0 -- 1.0 mV Sensitivity V/P -- 2.5 -- mV/kPa Linearity(5) -- -1.0 -- 1.0 %VFSS Pressure Hysteresis(5) (0 to 10 kPa) -- -- 0.1 -- %VFSS Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) Temperature Hysteresis(5) (+15C to +40C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance -- -- 0.1 -- %VFSS TCVFSS -1.0 -- 1.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1300 -- 2550 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-151 Freescale Semiconductor, Inc. MPXC2011DT1 MPXC2012DT1 ORDERING INFORMATION The MPXC2011DT1/MPXC2012DT1 silicon pressure sensors are available in tape and reel. Device Type/Order No. Case No. Device Description Marking MPXC2011DT1 423A Chip Pak, 1/3 Gel Date Code, Lot ID MPXC2012DT1 423A Chip Pak, No Gel Date Code, Lot ID Packaging Information Tape Width Quantity 330 mm 24 mm 1000 pc/reel Freescale Semiconductor, Inc... Tape and Reel Reel Size 3-152 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA High Temperature Accuracy Integrated Silicon Pressure Sensor MPXH6300A SERIES for Measuring Absolute Pressure, On-Chip Signal Conditioned, Temperature Compensated Freescale Semiconductor, Inc... and Calibrated Motorola's MPXH6300A series sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPXH6300A series piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. INTEGRATED PRESSURE SENSOR 20 to 304 kPa (3.0 to 42 psi) 0.3 to 4.9 Volts Output SUPER SMALL OUTLINE PACKAGE Features * Improved Accuracy at High Temperature MPXH6300A6T1 CASE 1317 * Available in Small and Super Small Outline Packages * 1.5% Maximum Error over 0 to 85C * Ideally suited for Microprocessor or Microcontroller-Based Systems * Temperature Compensated from - 40 to +125C * Durable Thermoplastic (PPS) Surface Mount Package Application Examples * Aviation Altimeters MPXH6300AC6T1 CASE 1317A * Industrial Controls * Engine Control/Manifold Absolute Pressure (MAP) PIN NUMBER * Weather Station and Weather Reporting Device Barometers VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout 1 N/C 5 N/C 2 6 N/C 3 VS Gnd 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the chamfered corner of the package. PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-153 MPXH6300A SERIES Freescale Semiconductor, Inc. MAXIMUM RATINGS(1) Parametrics Symbol Value Units Pmax 1200 kPa Tstg -40 to +125 C Operating Temperature TA -40 to +125 C Output Source Current @ Full Scale Output(2) Io+ 0.5 mAdc Output Sink Current @ Minimum Pressure Offset(2) Io- -0.5 mAdc Maximum Pressure (P1 u P2) Storage Temperature NOTES: 1. Exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. Maximum Output Current is controlled by effective impedance from Vout to Gnd or Vout to VS in the application circuit. OPERATING CHARACTERISTICS (VS = 5.1 Vdc, TA = 25C unless otherwise noted, P1 Characteristic Min Typ Max Unit POP 20 -- 304 kPa Supply Voltage(1) VS 4.74 5.1 5.46 Vdc Supply Current Io -- 6.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2.) Symbol Minimum Pressure Offset(2) @ VS = 5.1 Volts (0 to 85C) Voff 0.241 0.306 0.371 Vdc Full Scale Output(3) @ VS = 5.1 Volts (0 to 85C) VFSO 4.847 4.912 4.977 Vdc Full Scale Span(4) @ VS = 5.1 Volts (0 to 85C) VFSS 4.476 4.606 4.736 Vdc Accuracy(5) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 16.2 -- mV/kPa Response Time(6) tR -- 1.0 -- ms Warm-Up Time(7) -- -- 20 -- ms Offset Stability(8) -- -- 0.25 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 3. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 4. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 5. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 8. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. 3-154 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. DIE FLUORO SILICONE GEL DIE COAT +5.1 V STAINLESS STEEL CAP MPXH6300A SERIES P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME VS Pin 2 MPXH6300A Vout Pin 4 100 nF GND Pin 3 to ADC 47 pF 51 K ABSOLUTE ELEMENT DIE BOND SEALED VACUUM REFERENCE Figure 3. Typical Application Circuit (Output Source Current Operation) Figure 2 illustrates the absolute sensing chip in the basic Super Small Outline chip carrier (Case 1317). Figure 3 shows a typical application circuit (output source current operation). 5.0 4.5 4.0 OUTPUT (Volts) 3.5 TRANSFER FUNCTION: Vout = Vs* (.00318*P-.00353) Error VS = 5.1 Vdc TEMP = 0 to 85C 3.0 2.5 MAX 2.0 TYP 1.5 1.0 0.5 0 MIN 20 35 50 65 80 95 110 125 140 155 170 185 200 215 230 245 260 275 290 305 Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SSOP (not to scale) Pressure (ref: to sealed vacuum) in kPa Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over 0 to 85C temperature range. The output will saturate outside of the rated pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The Motorola Sensor Device Data MPXH6300A series pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-155 Freescale Semiconductor, Inc. MPXH6300A SERIES Transfer Function (MPXH6300A) Nominal Transfer Value: Vout = VS x (0.00318 x P - 0.00353) (Pressure Error x Temp. Factor x 0.00318 x VS) VS = 5.1 0.36 Vdc Temperature Error Band MPXH6300A Series 4.0 Break Points 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 125 3 1 3 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 4.0 3.0 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 2.0 1.0 0.0 -1.0 60 20 100 140 180 220 260 Pressure (in kPa) 300 - 2.0 - 3.0 -4.0 Pressure Error (Max) 20 to 304 (kPa) 4.0 (kPa) ORDERING INFORMATION -- SUPER SMALL OUTLINE PACKAGE Device Type Options Case No. Basic Element Absolute, Element Only 1317 MPXH6300A6U Rails MPXH6300A Absolute, Element Only 1317 MPXH6300A6T1 Tape and Reel MPXH6300A Absolute, Axial Port 1317A MPXH6300AC6U Rails MPXH6300A Absolute, Axial Port 1317A MPXH6300AC6T1 Tape and Reel MPXH6300A Ported Element 3-156 MPX Series Order No. Packing Options For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXH6300A SERIES SURFACE MOUNTING INFORMATION MINIMUM RECOMMENDED FOOTPRINT FOR SUPER SMALL OUTLINE PACKAGES Surface mount board layout is a critical portion of the total design. The footprint for the semiconductor package must be the correct size to ensure proper solder connection interface between the board and the package. With the correct pad geometry, the packages will self-align when subjected to 0.050 1.27 TYP a solder reflow process. It is always recommended to fabricate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.387 9.83 Freescale Semiconductor, Inc... 0.150 3.81 0.027 TYP 8X 0.69 0.053 TYP 8X 1.35 inch mm Figure 5. SSOP Footprint (Case 1317 and 1317A) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-157 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 10 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors MPXM2010 SERIES The MPXM2010 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Motorola Preferred Device 0 to 10 kPa (0 to 1.45 psi) 25 mV FULL SCALE SPAN (TYPICAL) Features Freescale Semiconductor, Inc... * Temperature Compensated Over 0C to + 85C * Available in Easy-to-Use Tape & Reel MPAK PACKAGE * Ratiometric to Supply Voltage * Gauge Ported & Non Ported Options Application Examples * Respiratory Diagnostics SCALE 1:1 * Air Movement Control MPXM2010D/DT1 CASE 1320 * Controllers * Pressure Switching Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS 3 SCALE 1:1 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY SENSING ELEMENT 2 4 MPXM2010GS/GST1 CASE 1320A Vout+ PIN NUMBER Vout- 1 Gnd 3 VS 2 +Vout 4 -Vout 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). Preferred devices are Motorola recommended choices for future use and best overall value. REV 1 3-158 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXM2010 SERIES MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 75 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 10 kPa Supply Voltage(2) VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 24 25 26 mV Voff -1.0 -- 1.0 mV Sensitivity V/P -- 2.5 -- mV/kPa Linearity(5) -- -1.0 -- 1.0 %VFSS Pressure Hysteresis(5) (0 to 10 kPa) -- -- 0.1 -- %VFSS Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance -- -- 0.5 -- %VFSS TCVFSS -1.0 -- 1.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2550 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-159 Freescale Semiconductor, Inc. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. LEAST SQUARE DEVIATION LEAST SQUARES FIT EXAGGERATED PERFORMANCE CURVE RELATIVE VOLTAGE OUTPUT MPXM2010 SERIES STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION Figure 3 shows the minimum, maximum and typical output characteristics of the MPXM2010 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. VS = 10 Vdc TA = 25C P1 > P2 30 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 25 20 aMAX 15 TYP SPAN RANGE (TYP) 10 MIN 5 0 -5 kPa PSI 2.5 0.362 5 0.725 7.5 1.09 10 1.45 OFFSET (TYP) Figure 3. Output versus Pressure Differential ORDERING INFORMATION Device Type 3-160 Options Case No No. MPXM2010D Non-ported 1320 MPXM2010DT1 Non-ported, Tape and Reel 1320 MPXM2010GS Ported 1320A MPXM2010GST1 Ported, Tape and Reel 1320A For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 50 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors MPXM2053 SERIES The MPXM2053 device is a silicon piezoresistive pressure sensor providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Motorola Preferred Device 0 to 50 kPa (0 to 7.25 psi) 40 mV FULL SCALE SPAN (TYPICAL) Freescale Semiconductor, Inc... Features * Temperature Compensated Over 0C to + 85C * Available in Easy-to-Use Tape & Reel MPAK PACKAGE * Ratiometric to Supply Voltage * Gauge Ported & Non Ported Options Application Examples * Pump/Motor Controllers * Robotics SCALE 1:1 * Level Indicators MPXM2053D/DT1 CASE 1320 * Medical Diagnostics * Pressure Switching * Non-Invasive Blood Pressure Measurement Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. VS SCALE 1:1 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY X-ducer SENSING ELEMENT 2 4 MPXM2053GS/GST1 CASE 1320A Vout+ Vout- 1 PIN NUMBER 1 Gnd 3 VS 2 +Vout 4 -Vout GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). Preferred devices are Motorola recommended choices for future use and best overall value. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-161 Freescale Semiconductor, Inc. MPXM2053 SERIES MAXIMUM RATINGS(NOTE) Rating Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C TA - 40 to +125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Typ Max Unit 0 -- 50 kPa -- 10 16 Vdc -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 -- 1.0 mV Sensitivity V/P -- 0.8 -- mV/kPa Linearity(5) -- - 0.6 -- 0.4 %VFSS Pressure Hysteresis(5) (0 to 50 kPa) -- -- 0.1 -- %VFSS Temperature Hysteresis(5) (- 40C to +125C) -- -- 0.5 -- %VFSS TCVFSS -2.0 -- 2.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Pressure Range(1) POP Supply Voltage(2) VS Supply Current Io Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance Min Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-162 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. MPXM2053 SERIES LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE LEAST SQUARE DEVIATION STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. Figure 3 shows the minimum, maximum and typical output characteristics of the MPXM2053 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. VS = 10 Vdc TA = 25C P1 > P2 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 30 25 20 TYP SPAN RANGE (TYP) MAX 15 10 MIN 5 kPa PSI 0 -5 0 12.5 1.8 25 3.6 37.5 5.4 50 7.25 OFFSET (TYP) Figure 3. Output versus Pressure Differential ORDERING INFORMATION Device Type Options Case No No. MPXM2053D Non-ported 1320 MPXM2053DT1 Non-ported, Tape and Reel 1320 MPXM2053GS Ported 1320A MPXM2053GST1 Ported, Tape and Reel 1320A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-163 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 100 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors MPXM2102 SERIES The MPXM2102 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Motorola Preferred Device 0 to 100 kPa (0 to 14.5 psi) 40 mV FULL SCALE SPAN (TYPICAL) Freescale Semiconductor, Inc... Features * Temperature Compensated Over 0C to + 85C MPAK PACKAGE * Available in Easy-to-Use Tape & Reel * Ratiometric to Supply Voltage * Gauge Ported & Non Ported Options Application Examples * Pump/Motor Controllers * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters SCALE 1:1 CASE 1320 Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. SCALE 1:1 VS CASE 1320A 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY X-ducer SENSING ELEMENT 2 4 PIN NUMBER Vout+ Vout- 1 Gnd 3 VS 2 +Vout 4 -Vout 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). Preferred devices are Motorola recommended choices for future use and best overall value. REV 1 3-164 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXM2102 SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 200 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic POP Supply Voltage(2) VS Supply Current Full Scale Span(3) Offset(4) Freescale Semiconductor, Inc... Symbol Pressure Range(1) MPXM2102D/G Series MPXM2102A Series Sensitivity Linearity(5) MPXM2102D/G Series MPXM2102A Series Pressure Hysteresis(5) (0 to 100 kPa) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance Min Typ Max Unit 0 -- 100 kPa -- 10 16 Vdc Io -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 - 2.0 -- -- 1.0 2.0 mV V/P -- 0.4 -- mV/kPa -- -- - 0.6 - 1.0 -- -- 0.4 1.0 %VFSS -- -- 0.1 -- %VFSS -- -- 0.5 -- %VFSS TCVFSS -2.0 -- 2.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-165 Freescale Semiconductor, Inc. MPXM2102 SERIES LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. LEAST SQUARE DEVIATION LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. Figure 3 shows the minimum, maximum and typical output characteristics of the MPXM2102 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. 40 VS = 10 Vdc TA = 25C P1 > P2 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 30 25 20 TYP SPAN RANGE (TYP) MAX 15 10 MIN 5 kPa PSI 0 -5 0 25 3.62 50 7.25 75 10.87 100 14.5 OFFSET (TYP) Figure 3. Output versus Pressure Differential ORDERING INFORMATION Device Type 3-166 Options Case Type MPXM2102D Non-ported 1320 MPXM2102DT1 Non-ported, Tape and Reel 1320 MPXM2102GS Ported 1320A MPXM2102GST1 Ported, Tape and Reel 1320A MPXM2102A Non-ported 1320 MPXM2102AT1 Non-ported, Tape and Reel 1320 MPXM2102AS Ported 1320A MPXM2102AST1 Ported, Tape and Reel 1320A For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA 200 kPa On-Chip Temperature Compensated & Calibrated Silicon Pressure Sensors MPXM2202 SERIES The MPXM2202 device is a silicon piezoresistive pressure sensors providing a highly accurate and linear voltage output -- directly proportional to the applied pressure. The sensor is a single, monolithic silicon diaphragm with the strain gauge and a thin-film resistor network integrated on-chip. The chip is laser trimmed for precise span and offset calibration and temperature compensation. Motorola Preferred Device 0 to 200 kPa (0 to 29 psi) 40 mV FULL SCALE SPAN (TYPICAL) Freescale Semiconductor, Inc... Features * Temperature Compensated Over 0C to + 85C MPAK PACKAGE * Available in Easy-to-Use Tape & Reel * Ratiometric to Supply Voltage * Gauge Ported & Non Ported Options Application Examples * Pump/Motor Controllers * Robotics * Level Indicators * Medical Diagnostics * Pressure Switching * Barometers * Altimeters SCALE 1:1 CASE 1320 Figure 1 shows a block diagram of the internal circuitry on the stand-alone pressure sensor chip. SCALE 1:1 VS CASE 1320A 3 THIN FILM TEMPERATURE COMPENSATION AND CALIBRATION CIRCUITRY X-ducer SENSING ELEMENT 2 4 PIN NUMBER Vout+ Vout- 1 Gnd 3 VS 2 +Vout 4 -Vout 1 GND Figure 1. Temperature Compensated Pressure Sensor Schematic VOLTAGE OUTPUT versus APPLIED DIFFERENTIAL PRESSURE The differential voltage output of the sensor is directly proportional to the differential pressure applied. The output voltage of the differential or gauge sensor increases with increasing pressure applied to the pressure side (P1) relative to the vacuum side (P2). Similarly, output voltage increases as increasing vacuum is applied to the vacuum side (P2) relative to the pressure side (P1). Preferred devices are Motorola recommended choices for future use and best overall value. REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-167 Freescale Semiconductor, Inc. MPXM2202 SERIES MAXIMUM RATINGS(NOTE) Rating Symbol Value Unit Pmax 400 kPa Tstg - 40 to +125 C Operating Temperature TA - 40 to +125 NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. C Maximum Pressure (P1 > P2) Storage Temperature OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Characteristic Symbol Pressure Range(1) POP Supply Voltage(2) VS Supply Current Full Scale Span(3) Freescale Semiconductor, Inc... Offset(4) MPXM2202D/G Series MPXM2202A Series Sensitivity Linearity(5) MPXM2202D/G Series MPXM2202A Series Pressure Hysteresis(5) (0 to 100 kPa) Temperature Hysteresis(5) (- 40C to +125C) Temperature Effect on Full Scale Span(5) Temperature Effect on Offset(5) Input Impedance Min Typ Max Unit 0 -- 200 kPa -- 10 16 Vdc Io -- 6.0 -- mAdc VFSS 38.5 40 41.5 mV Voff -1.0 - 2.0 -- -- 1.0 2.0 mV V/P -- 0.2 -- mV/kPa -- -- - 0.6 - 1.0 -- -- 0.4 1.0 %VFSS -- -- 0.1 -- %VFSS -- -- 0.5 -- %VFSS TCVFSS -2.0 -- 2.0 %VFSS TCVoff -1.0 -- 1.0 mV Zin 1000 -- 2500 Zout 1400 -- 3000 Response Time(6) (10% to 90%) tR -- 1.0 -- ms Warm-Up -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS Output Impedance NOTES: 1. 1.0 kPa (kiloPascal) equals 0.145 psi. 2. Device is ratiometric within this specified excitation range. Operating the device above the specified excitation range may induce additional error due to device self-heating. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 5. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure, using end point method, over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * TcSpan: Output deviation at full rated pressure over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 0 to 85C, relative to 25C. 6. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 7. Offset stability is the product's output deviation when subjected to 1000 hours of Pulsed Pressure, Temperature Cycling with Bias Test. 3-168 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LINEARITY Linearity refers to how well a transducer's output follows the equation: Vout = Voff + sensitivity x P over the operating pressure range. There are two basic methods for calculating nonlinearity: (1) end point straight line fit (see Figure 2) or (2) a least squares best line fit. While a least squares fit gives the "best case" linearity error (lower numerical value), the calculations required are burdensome. Conversely, an end point fit will give the "worst case" error (often more desirable in error budget calculations) and the calculations are more straightforward for the user. Motorola's specified pressure sensor linearities are based on the end point straight line method measured at the midrange pressure. MPXM2202 SERIES LEAST SQUARES FIT RELATIVE VOLTAGE OUTPUT EXAGGERATED PERFORMANCE CURVE LEAST SQUARE DEVIATION STRAIGHT LINE DEVIATION END POINT STRAIGHT LINE FIT OFFSET 50 PRESSURE (% FULLSCALE) 100 Figure 2. Linearity Specification Comparison ON-CHIP TEMPERATURE COMPENSATION and CALIBRATION A silicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. Figure 3 shows the minimum, maximum and typical output characteristics of the MPXM2202 series at 25C. The output is directly proportional to the differential pressure and is essentially a straight line. 40 35 OUTPUT (mVdc) Freescale Semiconductor, Inc... 0 VS = 10 Vdc TA = 25C P1 > P2 TYP 30 25 SPAN RANGE (TYP) MAX 20 15 10 MIN 5 0 -5 kPa 0 PSI 50 7.25 25 100 14.5 75 125 150 21.75 175 OFFSET 200 29 PRESSURE Figure 3. Output versus Pressure Differential ORDERING INFORMATION No Device Type/Order No. Options Case Type MPXM2202D Non-ported 1320 MPXM2202DT1 Non-ported, Tape and Reel 1320 MPXM2202GS Ported 1320A MPXM2202GST1 Ported, Tape and Reel 1320A MPXM2202A Non-ported 1320 MPXM2202AT1 Non-ported, Tape and Reel 1320 MPXM2202AS Ported 1320A MPXM2202AST1 Ported, Tape and Reel 1320A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-169 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor MPXV4006G On-Chip Signal Conditioned, SERIES Temperature Compensated and Calibrated The MPXV4006G series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This sensor combines a highly sensitive implanted strain gauge with advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. INTEGRATED PRESSURE SENSOR 0 to 6 kPa (0 to 0.87 psi) 0.2 to 4.7 V OUTPUT Freescale Semiconductor, Inc... Features * Temperature Compensated over 10 to 60C * Ideally Suited for Microprocessor or Microcontroller- Based Systems SMALL OUTLINE PACKAGE THROUGH-HOLE SMALL OUTLINE PACKAGE SURFACE MOUNT J * Available in Gauge Surface Mount (SMT) or Through- hole (DIP) Configurations * Durable Thermoplastic (PPS) Package MPXV4006G6U CASE 482 VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY MPXV4006G7U CASE 482B Vout MPXV4006GC6U CASE 482A MPXV4006GC7U CASE 482C PINS 1, 5, 6, 7, AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND Figure 1. Fully Integrated Pressure Sensor Schematic PIN NUMBER MPXV4006GP CASE 1369 1 N/C 5 N/C 2 6 N/C 3 VS Gnd 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. MPXV4006DP CASE 1351 Replaces MPXT4006D/D REV 4 3-170 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV4006G SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 24 kPa Tstg - 30 to +100 C TA +10 to +60 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Characteristic Pressure Range Supply Voltage(1) Freescale Semiconductor, Inc... Supply Current Symbol Min Typ Max Unit POP 0 -- 6.0 kPa VS 4.75 5.0 5.25 Vdc IS -- -- 10 mAdc Full Scale Span(2) (RL = 51k) VFSS -- 4.6 -- V Offset(3)(5) (RL = 51k) Voff 0.100 0.225 0.430 V V/P -- 766 -- mV/kPa -- -- -- 5.0 %VFSS Sensitivity Accuracy(4)(5) (10 to 60C) NOTES: 1. Device is ratiometric within this specified excitation range. 2. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * Offset Stability: Output deviation, after 1000 temperature cycles, 30 to 100C, and 1.5 million pressure cycles, with minimum rated pressure applied. * TcSpan: Output deviation over the temperature range of 10 to 60C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 10 to 60C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 5. Auto Zero at Factory Installation: Due to the sensitivity of the MPXV4006G, external mechanical stresses and mounting position can affect the zero pressure output reading. To obtain the 5% FSS accuracy, the device output must be "autozeroed'' after installation. Autozeroing is defined as storing the zero pressure output reading and subtracting this from the device's output during normal operations. * Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-171 Freescale Semiconductor, Inc. MPXV4006G SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING test for dry air, and other media, are available from the factory. Contact the factory for information regarding media tolerance in your application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum and maximum output curves are shown for operation over a temperature range of 10C to 60C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. DIE FLUOROSILICONE GEL DIE COAT +5 V STAINLESS STEEL CAP P1 WIRE BOND Vout THERMOPLASTIC CASE OUTPUT Vs IPS LEAD FRAME m 1.0 F m 0.01 F GND 470 pF P2 DIE BOND DIFFERENTIAL SENSING ELEMENT Figure 2. Cross-Sectional Diagram (Not to Scale) Figure 3. Recommended power supply decoupling and output filtering recommendations. For additional output filtering, please refer to Application Note AN1646. 5.0 OUTPUT (V) Freescale Semiconductor, Inc... The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip. Figure 2 illustrates the gauge configuration in the basic chip carrier (Case 482). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPXV4006G series sensor operating characteristics are based on use of dry air as pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Internal reliability and qualification TRANSFER FUNCTION: 4.5 Vout = VS*[(0.1533*P) + 0.045] 5% VFSS 4.0 VS = 5.0 V 0.25 Vdc TEMP = 10 to 60C 3.5 3.0 TYPICAL 2.5 2.0 MAX 1.5 MIN 1.0 0.5 0 0 3 DIFFERENTIAL PRESSURE (kPa) 6 Figure 4. Output versus Pressure Differential (See Note 5 in Operating Characteristics) 3-172 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV4006G SERIES PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola pres- Freescale Semiconductor, Inc... Part Number sure sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Case Type Pressure (P1) Side Identifier MPXV4006G6U/T1 482 Stainless Steel Cap MPXV4006GC6U/T1 482A Side with Port Attached MPXV4006G7U 482B Stainless Steel Cap MPXV4006GC7U 482C Side with Port Attached MPXV4006GP 1369 Side with Port Attached MPXV4006DP 1351 Side with Part Marking ORDERING INFORMATION MPXV4006G series pressure sensors are available in the basic element package or with pressure ports. Two packing options are offered for the 482 and 482A case configurations. Device Type Basic Element Ported Element Options Case No. MPX Series Order No. Packing Options Marking Element Only 482 MPXV4006G6U Rails MPXV4006G Element Only 482 MPXV4006G6T1 Tape and Reel MPXV4006G Element Only 482 MPXV4006G7U Rails MPXV4006G Axial Port 482A MPXV4006GC6U Rails MPXV4006G Axial Port 482A MPXV4006GC6T1 Tape and Reel MPXV4006G Axial Port 482A MPXV4006GC7U Rails MPXV4006G Side Port 1369 MPXV4006GP Trays MPXV4006G Dual Port 1351 MPXV4006DP Trays MPXV4006G MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct footprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-173 Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPXV4115V SERIES Temperature Compensated Freescale Semiconductor, Inc... and Calibrated The MPXV4115V series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, particularly those employing a microcontroller with A/D inputs. This transducer combines advanced micromachining techniques, thin-film metallization and bipolar processing to provide an accurate, high-level analog output signal that is proportional to the applied pressure/vacuum. The small form factor and high reliability of on-chip integration make the Motorola sensor a logical and economical choice for the automotive system designer. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. INTEGRATED PRESSURE SENSOR -115 to 0 kPa (-16.7 to 2.2 psi) 0.2 to 4.6 V OUTPUT SMALL OUTLINE PACKAGE Features * 1.5 % Maximum error over 0 to 85C * Temperature Compensated from -40 + 125C * Ideally Suited for Microprocessor or Microcontroller-Based Systems * Durable Thermoplastic (PPS) Surface Mount Package MPXV4115VC6U CASE 482A Application Examples * Vacuum Pump Monitoring * Brake Booster Monitoring VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY MPXV4115V6U CASE 482 Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND PIN NUMBER 1 N/C 5 N/C 2 VS Gnd 6 N/C 3 7 N/C 4 Vout 8 N/C Figure 1. Fully Integrated Pressure Sensor Schematic NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. REV 1 3-174 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV4115V SERIES MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure Storage Temperature Operating Temperature Symbol Value Unit Pmax 400 kPa Tstg - 40 to + 125 C TA -40 to + 125 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5 Vdc, TA = 25 C unless otherwise noted. Decoupling circuit shown in Figure 3 required to meet electrical specifications.) Characteristic Symbol Min Typ Max Unit Pressure Range (Differential mode, Vacuum on metal cap side, Atmospheric pressure on back side) POP -115 -- 0 kPa VS 4.75 5 5.25 Vdc Supply Voltage(1) Freescale Semiconductor, Inc... Supply Current Io -- 6.0 10 mAdc Full Scale Output (2) (0 to 85 C) (Pdiff = 0 kPa) 2 VFSO 4.535 4.6 4.665 Vdc Full Scale Span (3) (0 to 85 C) @Vs = 5.0 V VFSS Accuracy (4) (0 to 85 C) 4.4 Vdc -- -- 1.5% %VFSS V/P -- 38.26 -- mV/kPa Response Time (5) tR -- 1.0 -- ms Output Source Current at Full Scale Output Io -- 0.1 -- mAdc Warm-Up Time (6) -- -- 20 -- ms -- 0.5 -- %VFSS Sensitivity Offset Stability (7) NOTES: 1. Device is ratiometric within the specified excitation voltage range. 2. Full-scale output is defined as the output voltage at the maximum or full-rated pressure. 3. Full-scale span is defined as the algebraic difference between the output voltage at full-rated pressure and the output voltage at the minimum-rated pressure. 4. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25 C due to all sources of errors, including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 5. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 6. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 7. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-175 Freescale Semiconductor, Inc. MPXV4115V SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING Figure 3 shows the recommended decoupling circuit for interfacing the output of the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 4 shows the sensor output signal relative to differential pressure input. Typical, minimum and maximum output curves are shown for operation over a temperature range of 0C to 85C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. DIE FLUOROSILICONE GEL DIE COAT +5 V STAINLESS STEEL CAP P1 WIRE BOND Vout THERMOPLASTIC CASE OUTPUT Vs IPS LEAD FRAME m 1.0 F m 0.01 F GND 470 pF P2 DIE BOND DIFFERENTIAL SENSING ELEMENT Figure 2. Cross-Sectional Diagram (Not to Scale) Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. TRANSFER FUNCTION MPXV4115V 5 OUTPUT (VOLTS) Freescale Semiconductor, Inc... The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip. Figure 2 illustrates the gauge configuration in the basic chip carrier (Case 482). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPXV4115V series sensor operating characteristics are based on use of dry air as pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Internal reliability and qualification test for dry air, and other media, are available from the factory. Contact the factory for information regarding media tolerance in your application. TRANSFER FUNCTION: 4.5 V = V *[(0.007652*P) + 0.92] (Pressure error out S 4 *Temp Factor*0.007652*VS) VS = 5.0 V 0.25 Vdc 3.5 TEMP = 0-85 C 3 2.5 2 1.5 MAX MIN 1 0.5 0 -115 -95 -75 -55 Vout vs. VACUUM -35 -15 Figure 4. Applied Vacuum in kPa (below atmospheric pressure) 3-176 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV4115V SERIES ORDERING INFORMATION The MPXV4115V series pressure sensors are available in the basic element package or with a pressure port. Two packing options are also offered. Device Type Case No No. MPXV4115V6U Packing Options Device Marking 482 Rails MPXV4115V MPXV4115V6T1 482 Tape and Reel MPXV4115V MPXV4115VC6U 482A Rails MPXV4115V MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Freescale Semiconductor, Inc... Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-177 Freescale Semiconductor, Inc. MPXV4115V SERIES Transfer Function ) Nominal Transfer Value: Vout = VS (P x 0.007652 ) 0.92) +/- (Pressure Error x Temp. Factor x 0.007652 x VS) VS = 5 V 0.25 Vdc Temperature Error Band MPXV4115V Series 4.0 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 +125 3 1 3 0.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0 to -40C and from 85 to 125C. Pressure Error Band 1.950 1.725 Pressure Error (kPa) Freescale Semiconductor, Inc... 1.0 1.500 0 -115 -100 -85 -60 -45 -30 -15 Pressure in kPa (below atmospheric) 0 -1.500 - 1.725 - 1.950 Pressure -115 to 0 kPa 3-178 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Error (Max) "1.725 (kPa) Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPXV5004G SERIES Temperature Compensated and Calibrated INTEGRATED PRESSURE SENSOR 0 to 3.92 kPa (0 to 400 mm H2O) 1.0 to 4.9 V OUTPUT Freescale Semiconductor, Inc... The MPXV5004G series piezoresistive transducer is a state-of-the-art monolithic silicon pressure sensor designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This sensor combines a highly sensitive implanted strain gauge with advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure. Features SMALL OUTLINE PACKAGE SURFACE MOUNT * Temperature Compensated over 10 to 60C SMALL OUTLINE PACKAGE THROUGH-HOLE * Available in Gauge Surface Mount (SMT) or Through- hole (DIP) Configurations * Durable Thermoplastic (PPS) Package Application Examples * Washing Machine Water Level * Ideally Suited for Microprocessor or Microcontroller- Based Systems MPXV5004G6U CASE 482 MPXV5004GC7U CASE 482C VS J THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY MPXV5004GC6U CASE 482A Vout MPXV5004G7U CASE 482B PINS 1, 5, 6, 7, AND 8 ARE NO CONNECTS FOR SMALL OUTLINE PACKAGE DEVICE GND Figure 1. Fully Integrated Pressure Sensor Schematic MPXV5004GP CASE 1369 MPXV5004DP CASE 1351 PIN NUMBER 1 N/C 5 N/C 2 VS Gnd 6 N/C 3 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is noted by the notch in the lead. MPXV5004GVP CASE 1368 REV 5 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-179 MPXV5004G SERIES Freescale Semiconductor, Inc. MAXIMUM RATINGS(NOTE) Parametrics Maximum Pressure (P1 > P2) Storage Temperature Operating Temperature Symbol Value Unit Pmax 16 kPa Tstg - 30 to +100 C TA 0 to +85 C NOTE: Exposure beyond the specified limits may cause permanent damage or degradation to the device. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 > P2. Decoupling circuit shown in Figure 3 required to meet electrical specifications) Symbol Min Typ Max Unit POP 0 -- 3.92 400 kPa mm H2O Supply Voltage(1) VS 4.75 5.0 5.25 Vdc Supply Current IS -- -- 10 mAdc Characteristic Freescale Semiconductor, Inc... Pressure Range Span at 306 mm H2O (3 kPa)(2) VFSS -- 3.0 -- V Offset(3)(5) Voff 0.75 1.00 1.25 V Sensitivity V/P -- 1.0 9.8 -- V/kPa mV/mm H2O -- -- -- 1.5 2.5 %VFSS %VFSS Accuracy(4)(5) 0 to 100 mm H2O 100 to 400 mm H2O (10 to 60C) (10 to 60C) NOTES: 1. Device is ratiometric within this specified excitation range. 2. Span is defined as the algebraic difference between the output voltage at specified pressure and the output voltage at the minimum rated pressure. 3. Offset (Voff) is defined as the output voltage at the minimum rated pressure. 4. Accuracy (error budget) consists of the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C. * Offset Stability: Output deviation, after 1000 temperature cycles, 30 to 100C, and 1.5 million pressure cycles, with minimum rated pressure applied. * TcSpan: Output deviation over the temperature range of 10 to 60C, relative to 25C. * TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 10 to 60C, relative to 25C. * Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C. 5. Auto Zero at Factory Installation: Due to the sensitivity of the MPXV5004G, external mechanical stresses and mounting position can affect the zero pressure output reading. Autozeroing is defined as storing the zero pressure output reading and subtracting this from the device's output during normal operations. Reference AN1636 for specific information. The specified accuracy assumes a maximum temperature change of 5 C between autozero and measurement. * 3-180 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV5004G SERIES ON-CHIP TEMPERATURE COMPENSATION, CALIBRATION AND SIGNAL CONDITIONING test for dry air, and other media, are available from the factory. Contact the factory for information regarding media tolerance in your application. Figure 3 shows the recommended decoupling circuit for interfacing the output of the MPXV5004G to the A/D input of the microprocessor or microcontroller. Proper decoupling of the power supply is recommended. Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum and maximum output curves are shown for operation over a temperature range of 10C to 60C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range. DIE FLUOROSILICONE GEL DIE COAT STAINLESS STEEL CAP +5 V P1 WIRE BOND Vout THERMOPLASTIC CASE OUTPUT Vs IPS LEAD FRAME m 1.0 F m 0.01 F GND 470 pF P2 DIE BOND DIFFERENTIAL SENSING ELEMENT Figure 2. Cross-Sectional Diagram (Not to Scale) Figure 3. Recommended power supply decoupling and output filtering. For additional output filtering, please refer to Application Note AN1646. 5.0 TRANSFER FUNCTION: Vout = VS*[(0.2*P) + 0.2] 1.5% VFSS VS = 5.0 V 0.25 Vdc 4.0 TEMP = 10 to 60C OUTPUT (V) Freescale Semiconductor, Inc... The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip. Figure 2 illustrates the gauge configuration in the basic chip carrier (Case 482). A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The MPXV5004G series sensor operating characteristics are based on use of dry air as pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Internal reliability and qualification TYPICAL 3.0 MAX MIN 2.0 1.0 2 kPa 200 mm H2O 4 kPa 400 mm H2O DIFFERENTIAL PRESSURE Figure 4. Output versus Pressure Differential (See Note 5 in Operating Characteristics) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-181 MPXV5004G SERIES Freescale Semiconductor, Inc. PRESSURE (P1)/VACUUM (P2) SIDE IDENTIFICATION TABLE Motorola designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing silicone gel which isolates the die from the environment. The Motorola pressure Part Number Case Type MPXV5004GC6U/T1 Pressure (P1) Side Identifier 482A MPXV5004G6U/T1 Freescale Semiconductor, Inc... sensor is designed to operate with positive differential pressure applied, P1 > P2. The Pressure (P1) side may be identified by using the table below: Side with Port Attached 482 Stainless Steel Cap MPXV5004GC7U 482C Side with Port Attached MPXV5004G7U 482B Stainless Steel Cap MPXV5004GP 1369 Side with Port Attached MPXV5004DP 1351 Side with Port Marking MPXV5004GVP 1368 Stainless Steel Cap ORDERING INFORMATION MPXV5004G series pressure sensors are available in the basic element package or with a pressure port. Two packing options are offered for the surface mount configuration. No Device Type / Order No. Case No No. Packing Options Device Marking MPXV5004G6U 482 Rails MPXV5004G MPXV5004G6T1 482 Tape and Reel MPXV5004G MPXV5004GC6U 482A Rails MPXV5004G MPXV5004GC6T1 482A Tape and Reel MPXV5004G MPXV5004GC7U 482C Rails MPXV5004G MPXV5004G7U 482B Rails MPXV5004G MPXV5004GP 1369 Trays MPXV5004G MPXV5004DP 1351 Trays MPXV5004G MPXV5004GVP 1368 Trays MPXV5004G INFORMATION FOR USING THE SMALL OUTLINE PACKAGE (CASE 482) MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct fottprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.100 TYP 8X 2.54 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm SCALE 2:1 Figure 5. SOP Footprint (Case 482) 3-182 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA High Temperature Accuracy Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, MPXV6115VC6U Temperature Compensated Freescale Semiconductor, Inc... and Calibrated Motorola's MPXV6115VC6U sensor integrates on-chip, bipolar op amp circuitry and thin film resistor networks to provide a high output signal and temperature compensation. The small form factor and high reliability of on-chip integration make the Motorola pressure sensor a logical and economical choice for the system designer. The MPXV6115VC6U piezoresistive transducer is a state-of-the-art, monolithic, signal conditioned, silicon pressure sensor. This sensor combines advanced micromachining techniques, thin film metallization, and bipolar semiconductor processing to provide an accurate, high level analog output signal that is proportional to applied pressure. Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip. INTEGRATED PRESSURE SENSOR -115 to 0 kPa (-16.7 to 2.2 psi) 0.2 to 4.6 Volts Output SMALL OUTLINE PACKAGE Features * Improved Accuracy at High Temperature * 1.5% Maximum Error over 0 to 85C MPXV6115VC6U CASE 482A * Ideally suited for Microprocessor or Microcontroller-Based Systems * Temperature Compensated from - 40 to +125C * Durable Thermoplastic (PPS) Surface Mount Package Application Examples * Vacuum Pump Monitoring * Brake Booster Monitoring VS THIN FILM TEMPERATURE COMPENSATION AND GAIN STAGE #1 SENSING ELEMENT PIN NUMBER 1 N/C 5 N/C 2 VS Gnd 6 N/C 3 7 N/C 4 Vout 8 N/C NOTE: Pins 1, 5, 6, 7, and 8 are internal device connections. Do not connect to external circuitry or ground. Pin 1 is denoted by the notch in the lead. GAIN STAGE #2 AND GROUND REFERENCE SHIFT CIRCUITRY Vout PINS 1, 5, 6, 7 AND 8 ARE NO CONNECTS GND Figure 1. Fully Integrated Pressure Sensor Schematic REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-183 Freescale Semiconductor, Inc. MPXV6115VC6U MAXIMUM RATINGS(1) Parametrics Symbol Value Units Pmax 400 kPa Tstg -40 to +125 C Operating Temperature TA -40 to +125 C Output Source Current @ Full Scale Output(2) Io+ 0.5 mAdc Output Sink Current @ Minimum Pressure Offset(2) Io- -0.5 mAdc Maximum Pressure (P1 u P2) Storage Temperature NOTES: 1. Exposure beyond the specified limits may cause permanent damage or degradation to the device. 2. Maximum Output Current is controlled by effective impedance from Vout to Gnd or Vout to VS in the application circuit. OPERATING CHARACTERISTICS (VS = 5.0 Vdc, TA = 25C unless otherwise noted, P1 Characteristic Min Typ Max Unit POP -115 -- 0 kPa Supply Voltage(1) VS 4.75 5.0 5.25 Vdc Supply Current Io -- 6.0 10 mAdc Pressure Range Freescale Semiconductor, Inc... u P2.) Symbol Full Scale Output(2) @ VS = 5.0 Volts (0 to 85C) (Pdiff = 0 kPa) VFSO 4.534 4.6 4.665 Vdc Full Scale Span(3) @ VS = 5.0 Volts (0 to 85C) VFSS -- 4.4 -- Vdc Accuracy(4) (0 to 85C) -- -- -- 1.5 %VFSS Sensitivity V/P -- 38.26 -- mV/kPa Response Time(5) tR -- 1.0 -- ms Warm-Up Time(6) -- -- 20 -- ms Offset Stability(7) -- -- 0.5 -- %VFSS NOTES: 1. Device is ratiometric within this specified excitation range. 2. Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure. 3. Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure. 4. Accuracy is the deviation in actual output from nominal output over the entire pressure range and temperature range as a percent of span at 25C due to all sources of error including the following: * Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range. * Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied. * Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from minimum or maximum rated pressure at 25C. * TcSpan: Output deviation over the temperature range of 0 to 85C, relative to 25C. * TcOffset: Output deviation with minimum pressure applied, over the temperature range of 0 to 85C, relative to 25C. 5. Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. 6. Warm-up Time is defined as the time required for the product to meet the specified output voltage after the pressure has been stabilized. 7. Offset Stability is the product's output deviation when subjected to 1000 cycles of Pulsed Pressure, Temperature Cycling with Bias Test. 3-184 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. DIE FLUOROSILICONE GEL DIE COAT MPXV6115VC6U STAINLESS STEEL CAP P1 WIRE BOND THERMOPLASTIC CASE LEAD FRAME +5.0 V P2 DIE BOND DIFFERENTIAL SENSING ELEMENT VS Pin 2 MPXV6115VC6U 100 nF Vout Pin 4 to ADC 47 pF GND Pin 3 51 K Figure 3. Typical Application Circuit (Output Source Current Operation) Figure 2 illustrates the absolute sensing chip in the basic Small Outline chip carrier (Case 482). Figure 3 shows a typical application circuit (output source current operation). TRANSFER FUNCTION MPXV6115VC6U 5 OUTPUT (VOLTS) Freescale Semiconductor, Inc... Figure 2. Cross Sectional Diagram SOP (Not to Scale) TRANSFER FUNCTION: 4.5 V = V *[(0.007652*P) + 0.92] (Pressure error out S 4 *Temp Factor*0.007652*VS) VS = 5.0 V 0.25 Vdc 3.5 TEMP = 0-85 C 3 2.5 2 1.5 MAX MIN 1 0.5 0 -115 -95 -75 -55 Vout vs. VACUUM -35 -15 0 Figure 4. Output versus Absolute Pressure Figure 4 shows the sensor output signal relative to pressure input. Typical minimum and maximum output curves are shown for operation over 0 to 85C temperature range. The output will saturate outside of the rated pressure range. A fluorosilicone gel isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the silicon diaphragm. The Motorola Sensor Device Data MPXV6115VC6U pressure sensor operating characteristics, internal reliability and qualification tests are based on use of dry air as the pressure media. Media other than dry air may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-185 Freescale Semiconductor, Inc. MPXV6115VC6U Transfer Function (MPXV6115VC6U) Nominal Transfer Value: Vout = VS x (0.007652 x P + 0.92) (Pressure Error x Temp. Factor x 0.007652 x VS) VS = 5.0 0.25 Vdc Temperature Error Band MPXV6115VC6U 4.0 Break Points 3.0 Temperature Error Factor 2.0 Temp Multiplier - 40 0 to 85 125 3 1 2 1.0 -40 -20 0 20 40 60 80 100 120 140 Temperature in C NOTE: The Temperature Multiplier is a linear response from 0C to -40C and from 85C to 125C Pressure Error Band Error Limits for Pressure 1.950 1.725 Pressure Error (kPa) Freescale Semiconductor, Inc... 0.0 1.500 0 -115 -100 -85 -60 -45 -30 -15 Pressure in kPa (below atmospheric) 0 -1.500 - 1.725 Pressure - 1.950 -115 to 0 kPa Error (Max) "1.725 (kPa) ORDERING INFORMATION -- SMALL OUTLINE PACKAGE Device Type Ported Element 3-186 Options Vacuum, Axial Port Case No. 482A MPX Series Order No. MPXV6115VC6U Packing Options Rails For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Marking MPXV6115V Motorola Sensor Device Data Freescale Semiconductor, Inc. MPXV6115VC6U SURFACE MOUNTING INFORMATION MINIMUM RECOMMENDED FOOTPRINT FOR SMALL OUTLINE PACKAGE Surface mount board layout is a critical portion of the total design. The footprint for the semiconductor package must be the correct size to ensure proper solder connection interface between the board and the package. With the correct pad geometry, the packages will self-align when subjected to a solder reflow process. It is always recommended to fabricate boards with a solder mask layer to avoid bridging and/or shorting between solder pads, especially on tight tolerances and/or tight layouts. 0.100 TYP 2.54 Freescale Semiconductor, Inc... 0.660 16.76 0.060 TYP 8X 1.52 0.300 7.62 0.100 TYP 8X 2.54 inch mm Figure 5. SOP Footprint (Case 482A) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-187 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN935 Compensating for Nonlinearity in the MPX10 Series Pressure Transducer Prepared by: Carl Demington Design Engineering Freescale Semiconductor, Inc... INTRODUCTION This application note describes a technique to improve the linearity of Motorola's MPX10 series (i.e., MPX10, MPXV10, and MPX12 pressure sensors) pressure transducers when they are interfaced to a microprocessor system. The linearization technique allows the user to obtain both high sensitivity and good linearity in a cost effective system. The MPX10, MPXV10 and MPX12 pressure transducers are semiconductor devices which give an electrical output signal proportional to the applied pressure over the pressure range of 0-10 kPa (0-75 mm Hg). These devices use a unique transverse voltage-diffused silicon strain-gauge which is sensitive to stress produced by pressure applied to a thin silicon diaphragm. One of the primary considerations when using a pressure transducer is the linearity of the transfer function, since this parameter has a direct effect on the total accuracy of the system, and compensating for nonlinearities with peripheral circuits is extremely complicated and expensive. The purpose of this document is to outline the causes of nonlinearity, the trade-offs that can be made for increased system accuracy, and a relatively simple technique that can be utilized to maintain system performance, as well as system accuracy. ORIGINS OF NONLINEARITY Nonlinearity in semiconductor strain-gauges is a topic that has been the target of many experiments and much discussion. Parameters such as resistor size and orientation, surface impurity levels, oxide passivation thickness and growth temperatures, diaphragm size and thickness are all contributors to nonlinear behavior in silicon pressure transducers. The Motorola X-ducer was designed to minimize these effects. This goal was certainly accomplished in the MPX2000 series which have a maximum nonlinearity of 0.1% FS. However, to obtain the higher sensitivity of the MPX10 series, a maximum nonlinearity of 1% FS has to be allowed. The primary cause of the additional nonlinearity in the MPX10 series is due to the stress induced in the diaphragm by applied pressure being no longer linear. One of the basic assumptions in using semiconductor strain-gauges as pressure sensors is that the deflection of the diaphragm when pressure is applied is small compared to the thickness of the diaphragm. With devices that are very sensitive in the low pressure ranges, this assumption is no longer valid. The deflection of the diaphragm is a considerable percentage of the diaphragm thickness, especially in devices with higher sensitivities (thinner diaphragms). The resulting stresses do not vary linearly with applied pressure. This behavior can be reduced somewhat by increasing the area of the diaphragm and consequently thickening the diaphragm. Due to the constraint, the device is required to have high sensitivity over a fairly small pressure range, and the nonlinearity cannot be eliminated. Much care was given in the design of the MPX10 series to minimize the nonlinear behavior. However, for systems which require greater accuracy, external techniques must be used to account for this behavior. PERFORMANCE OF AN MPX DEVICE The output versus pressure of a typical MPX12 along with an end-point straight line is shown in Figure 1. All nonlinearity errors are referenced to the end-point straight line (see data sheet). Notice there is an appreciable deviation from the end-point straight line at midscale pressure. This shape of curve is consistent with MPX10 and MPXV10, as well as MPX12 devices, with the differences between the parts being the magnitude of the deviation from the end-point line. The major tradeoff that can be made in the total device performance is sensitivity versus linearity. Figure 2 shows the relationship between full scale span and nonlinearity error for the MPX10 series of devices. The data shows the primary contribution to nonlinearity is nonproportional stress with pressure, while assembly and packaging stress (scatter of the data about the line) is fairly small and well controlled. It can be seen that relatively good accuracies (<0.5% FS) can be achieved at the expense of reduced sensitivity, and for high sensitivity the nonlinearity errors increase rapidly. The data shown in Figure 2 was taken at room temperature with a constant voltage excitation of 3.0 volts. REV 3 3-188 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 90 0.5 0.4 0.3 0.2 0.1 80 60 50 B0 Vout (mV) 70 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 0 - 0.1 - 0.2 - 0.3 - 0.4 - 0.5 20 25 30 35 40 45 50 55 60 65 70 SPAN (mV) Figure 1. MPX12 Linearity Analysis Raw Data Figure 3. MPX10 Linearity Analysis -- Correlation of B0 Vout = B0 + B1 (P) + B2 (P)2 1.1 1.0 4.0 B1 = 0.2055 + 1.598E - 3*(SPAN) + 1.723E - 4*(SPAN)2 0.9 0.8 3.0 B1 LINEARITY (% FS) 2.0 0.7 0.6 0.5 1.0 0.4 0 0 10 20 30 40 50 60 70 80 0.3 0.2 20 90 25 30 35 40 45 50 55 60 65 70 SPAN (mV) SPAN (mV) Figure 4. MPX10 Linearity Analysis -- Correlation of B1 Vout = B0 + B1 (P) + B2 (P)2 Figure 2. MPX10 Series Span versus Linearity 0.0030 COMPENSATION FOR NONLINEARITY The nonlinearity error shown in Figure 1 arises from the assumption that the output voltage changes with respect to pressure in the following manner: Vout = Voff + sens*P where Voff = output voltage at zero pressure differential sens = sensitivity of the device P = applied pressure [1] 0.0015 0.0005 [2] where B0, B1, B2, B3, etc. are sensitivity coefficients. In order to determine the sensitivity coefficients given in equation [2] for the MPX10 series of pressure transducers, a polynomial regression analysis was performed on data taken from 139 devices with full scale spans ranging from 30 to 730 mV. It was found that second order terms are sufficient to give excellent agreement with experimental data. The calculated regression coefficients were typically 0.999999+ with the worst case being 0.99999. However, these sensitivity coefficients demonstrated a strong correlation with the full scale span of the device for which they were calculated. The correlation of B0, B1, and B2 with full scale span is shown in Figures 3 through 5. Motorola Sensor Device Data B2 = -1.293E - 13*(SPAN)5.68 0.0020 0.0010 It is obvious that the true output does not follow this simple straight line equation. Therefore, if an expression could be determined with additional higher order terms that more closely described the output behavior, increased accuracies would be possible. The output expression would then become Vout = Voff +(B0+B1*P+B2*P2+B3*P3 +. . .) 0.0025 -B 2 Freescale Semiconductor, Inc... B0 = 0.1045 - 0.00295*(SPAN) PRESSURE (torr) 5.0 -1.0 AN935 20 25 30 35 40 45 50 55 60 65 70 SPAN (mV) Figure 5. MPX10 Linearity Analysis -- Correlation of B2 Vout = B0 + B1 (P) + B2 (P)2 In order to simplify the determination of these coefficients for the user, further regression analysis was performed so that expressions could be given for each coefficient as a function of full scale span. This would then allow the user to do a single pressure measurement, a series of calculations, and analytically arrive at the equation of the line that describes the output behavior of the transducer. Nonlinearity errors were then calculated by comparing experimental data with the values calculated using equation [2] and the sensitivity coefficients given by the regression analysis. The resulting errors are shown in Figures 6 through 9 at various pressure points. While using this technique has been successful in reducing the errors due to nonlinearity, the considerable spread and large number of devices that showed errors >1% indicate this technique was not as successful as desired. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-189 Freescale Semiconductor, Inc. AN935 % 21.54 NO. OF UNITS LINEARITY ERROR (% FS) 30 19.38 27 24 Freescale Semiconductor, Inc... 21 17.23 General Fit P = 1/4 FS Average Error = 0.15 Standard Deviation = 0.212 15.08 18 12.92 15 10.77 12 8.62 9.0 6.46 6.0 4.31 3.0 2.15 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 6. Linearity Error of General Fit Equation at 1/4 FS % 16.15 NO. OF UNITS LINEARITY ERROR (% FS) 14.54 21 12.92 18 15 General Fit P = 1/2 FS Average Error = - 0.02 Standard Deviation = 0.391 11.31 9.69 12 8.08 6.46 9.0 4.85 6.0 3.23 3.0 1.62 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 7. Linearity Error of General Fit Equation at 1/2 FS 3-190 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN935 NO. OF UNITS % 12.31 LINEARITY ERROR (% FS) 16.5 11.08 15 13.5 12 9.85 General Fit P = 3/4 FS Average Error = - 0.10 Standard Deviation = 0.549 8.62 10.5 7.38 9.0 6.15 Freescale Semiconductor, Inc... 7.5 4.92 6.0 3.69 4.5 2.46 3.0 1.23 1.5 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 8. Linearity Error of General Fit Equation at 3/4 FS NO. OF UNITS 19.5 % 13.85 LINEARITY ERROR (% FS) 12.46 18 16.5 15 13.5 11.08 General Fit P = 1 FS Average Error = 0.11 Standard Deviation = 0.809 9.69 12 8.31 10.5 6.92 9.0 5.54 7.5 4.15 6.0 4.5 2.77 3.0 1.38 1.5 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 9. Linearity Error of General Fit Equation at FS Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-191 Freescale Semiconductor, Inc. AN935 devices having errors <0.5%, while only one of the devices was >1%. The sensitivity coefficients that are substituted into equation [2] for the different techniques are given in Table 1. It is important to note that for either technique the only measurement that is required by the user in order to clearly determine the sensitivity coefficients is the determination of the full scale span of the particular pressure transducer. A second technique that still uses a single pressure measurement as the input was investigated. In this method, the sensitivity coefficients are calculated using a piece-wise linearization technique where the total span variation is divided into four windows of 10 mV (i.e., 30-39.99, 40-49.99, etc.) and coefficients calculated for each window. The errors that arise out of using this method are shown in Figures 10 through 13. This method results in a large majority of the NO. OF UNITS % 37.69 LINEARITY ERROR (% FS) 33.92 48 Freescale Semiconductor, Inc... 42 36 30.15 General Fit P = 1/4 FS Average Error = 0.18 Standard Deviation = 0.159 26.38 22.62 30 18.85 24 15.08 18 11.31 12 7.54 6.0 3.77 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 10. Linearity Error of Piece-Wise Linear Fit at 1/4 FS Table 1. Comparison of Linearization Methods SPAN WINDOW B0 B1 B2 GENERAL FIT 0.1045 + 2.95E - 3X 0.2055 + 1.598E - 3X + 1.723E - 4X2 1.293E - 13X5.681 PIECE-WISE LINEAR FIT 30-39.99 0.08209 - 2.246E - 3X 40-49.99 0.1803 - 4.67E - 3X -0.119 + 1.655E - 2X -1.572E - 3 + 4.247E - 5X 50-59.99 0.1055 - 3.051E - 3X -0.355 + 2.126E - 2X -5.0813 - 3 + 1.116E - 4X -0.361 + 2.145E - 2X -5.928E - 3 + 1.259E - 4X 60-69.99 -0.288 + 3.473E - 3X 0.02433 = 1.430E - 2X -1.961E - 4 + 8.816E - 6X X = Full Scale Span 3-192 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN935 % 20 NO. OF UNITS LINEARITY ERROR (% FS) 27 18 24 21 Freescale Semiconductor, Inc... 18 16 General Fit P = 1/2 FS Average Error = 0.02 Standard Deviation = 0.267 14 12 15 10 12 8.0 9.0 6.0 6.0 4.0 3.0 2.0 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 11. Linearity Error of Piece-Wise Linear Fit at 1/2 FS NO. OF UNITS % 16.15 LINEARITY ERROR (% FS) 21 18 15 14.54 12.92 General Fit P = 3/4 FS Average Error = - 0.09 Standard Deviation = 0.257 11.31 9.69 12 8.08 9.0 6.46 4.85 6.0 3.23 3.0 1.62 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 12. Linearity Error of Piece-Wise Linear Fit at 3/4 PS Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-193 Freescale Semiconductor, Inc. AN935 NO. OF UNITS % 38.46 LINEARITY ERROR (% FS) 52.5 34.62 45 37.5 30.77 General Fit P = 1 FS Average Error = 0.13 Standard Deviation = 0.186 26.92 23.08 30 19.23 Freescale Semiconductor, Inc... 22.5 15.38 11.54 15 7.69 7.5 3.85 0.0 - 2.0 -1.8 -1.6 -1.4 -1.2 -1.0 - 0.8 - 0.6 - 0.4 - 0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Figure 13. Linearity Error of Piece-Wise Linear Fit at FS Once the sensitivity coefficients have been determined, a system can then be built that provides an accurate output function with pressure. The system shown in Figure 14 consists of a pressure transducer, a temperature compensation and amplification stage, an A/D converter, a microprocessor, and a display. The display block can be replaced with a control function if required. The A/D converter simply transforms the voltage signal to an input signal for the microprocessor, in which resides the look-up table of the transfer function generated from the previously determined sensitivity coefficients. The microprocessor can then drive a display or control circuit using standard techniques. X-DUCER DISPLAY MICROCONTROLLER MC68HC908QT4 TEMPERATURE COMPENSATION AND AMPLIFICATION Figure 14. Linearization System Block Diagram SUMMARY While at first glance this technique appears to be fairly complicated, it can be a very cost effective method of building a high-accuracy, high-sensitivity pressure-monitoring system for low-pressure ranges. 3-194 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR APPLICATION NOTE AN936 Mounting Techniques, Lead Forming and Testing of Motorola's MPX Series Pressure Sensors Prepared by: Randy Frank Motorola Inc., Semiconductor Products Sector Phoenix, Arizona Freescale Semiconductor, Inc... INTRODUCTION Motorola's MPX series pressure sensors are silicon piezoresistive strain-gauges offered in a chip-carrier package (see Figure 1). The exclusive chip-carrier package was developed to realize the advantages of high-speed, automated assembly and testing. In addition to high volume availability and low cost, the chip-carrier package offers users a number of packaging options. This Application Note describes several mounting techniques, offers lead forming recommendations, and suggests means of testing the MPX series of pressure sensors. DIFFERENTIAL PORT OPTION CASE 344C-01 Figure 1. MPX Pressure Sensor In Chip Carrier Package Shown with Port Options BASIC ELEMENT CASE 344-15 SUFFIX A / D GAUGE PORT CASE 344B-01 SUFFIX AP / GP AXIAL VACUUM PORT STOVEPIPE VACUUM PORT CASE 344G-01 CASE 344E-01 SUFFIX GVSX SUFFIX AS/GS DUAL PORT CASE 867C-05 SUFFIX DP AXIAL PORT CASE 867F-03 SUFFIX ASX / GSX GAUGE VACUUM PORT CASE 344D-01 SUFFIX GVP STOVEPIPE PORT CASE 344A-01 SUFFIX GVS BASIC ELEMENT CASE 867-08 SUFFIX A / D AXIAL VACUUM PORT CASE 867G-03 SUFFIX GVSX DUAL PORT CASE 344C-01 SUFFIX DP GAUGE PORT CASE 867B-04 SUFFIX AP / GP STOVEPIPE PORT CASE 867E-03 SUFFIX AS / GS AXIAL PORT CASE 344F-01 SUFFIX ASX / GSX GAUGE VACUUM PORT CASE 867D-04 SUFFIX GVP STOVEPIPE VACUUM PORT CASE 867A-04 SUFFIX GVS Figure 2. Chip Carrier and Available Ported Packages REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-195 Freescale Semiconductor, Inc. AN936 PORT ADAPTERS Freescale Semiconductor, Inc... Available Packages Motorola's chip-carrier package and available ports for attachment of 1/8 I.D. hose are made from a high temperature thermoplastic that can withstand temperature extremes from -50 to 150C (see Figure 2). The port adapters were designed for rivet or 5/32 screw attachment to panels, printed circuit boards or chassis mounting. Custom Port Adaptor Installation Techniques The Motorola MPX silicon pressure sensor is available in a basic chip carrier cell which is adaptable for attachment to customer specific housings/ports (Case 344 for 4-pin devices and Case 867 for 6-pin devices). The basic cell has chamfered shoulders on both sides which will accept an O-ring such as Parker Seal's silicone O-ring (p/n#2-015-S-469-40). Refer to Figure 3 for the recommended O-ring to sensor cell interface dimensions. The sensor cell may also be glued directly to a custom housing or port using many commercial grade epoxies or RTV adhesives which adhere to grade Valox 420, 30% glass reinforced polyester resin plastic or Union Carbide's Udel polysulfone (MPX2300DT1 only). Motorola recommends using Thermoset EP530 epoxy or an equivalent. The epoxy should be dispensed in a continuous bead around the case-to-port interface shoulder. Refer to Figure 4. Care must be taken to avoid gaps or voids in the adhesive bead to help ensure that a complete seal is made when the cell is joined to the port. The recommended cure conditions for Thermoset EP539 are 15 minutes at 150C. After cure, a simple test for gross leaks should be performed to ensure the integrity of the .114 .047 cell to port bond. Submerging the device in water for 5 seconds with full rated pressure applied to the port nozzle and checking for air bubbles will provide a good indication. TESTING MPX SERIES PRESSURE SENSORS Pressure Connection Testing of pressure sensing elements in the chip carrier package can be performed easily by using a clamping fixture which has an O-ring seal to attach to the beveled surface. Figure 8 shows a diagram of the fixture that Motorola uses to apply pressure or vacuum to unported elements. When performing tests on packages with ports, a high durometer tubing is necessary to minimize leaks, especially in higher pressure range sensors. Removal of tubing must be parallel to the port since large forces can be generated to the pressure port which can break the nozzle if applied at an angle. Whether sensors are tested with or without ports, care must be exercised so that force is not applied to the back metal cap or offset errors can result. Standard Port Attach Connection Motorola also offers standard port options designed to accept readily available silicone, vinyl, nylon or polyethylene tubing for the pressure connection. The inside dimension of the tubing selected should provide a snug fit over the port nozzle. Installation and removal of tubing from the port nozzle must be parallel to the nozzle to avoid undue stress which may break the nozzle from the port base. Whether sensors are used with Motorola's standard ports or customer specific housings, care must be taken to ensure that force is uniformly distributed to the package or offset errors may be induced. 0 .125 ADHESIVE BEAD .075 .037R 0 .210 CELL .021 Figure 3. Examples of Motorola Sensors in Custom Housings 3-196 Figure 4. Case to Port Interface www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 5.72 0.225 = DIAMETER MM DIMENSIONS IN INCHES AN936 F 4.55 0.179 3.81 0.150 3.40 0.134 2.54 0.100 2.39 0.094 0.36 (0.014) 1.27 0.050 0.36 (0.014) M A B A B M C M C M M 0.76 0.030 M 10.16 0.400 2.03 3 PL 0.080 14.48 0.570 3.96 0.156 16.23 0.639 Freescale Semiconductor, Inc... 1.60 0.063 35 2 6.35 0.250 3.96 0.156 6.35 0.250 13.66 13.51 0.538 0.532 F 2.21 2.13 0.087 SECTION F-F 0.084 0.36 (0.014) M A B M C M 2 PL 0.36 (0.014) A B C ZONE -D- WITHIN ZONE -D- Figure 5. Port Adapter Dimensions C R M B -A- TOP CLAMP AREA N 1 PIN 1 2 3 L 4 -T- SEATING PLANE J G F D 4 PL 0.136 (0.005) M T A M NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION -A- IS INCLUSIVE OF THE MOLD STOP RING. MOLD STOP RING NOT TO EXCEED 16.00 (0.630). DIM A B C D F G J L M N R INCHES MIN MAX 0.595 0.630 0.514 0.534 0.200 0.220 0.016 0.020 0.048 0.064 0.100 BSC 0.014 0.016 0.695 0.725 30_ NOM 0.475 0.495 0.430 0.450 STYLE 1: PIN 1. 2. 3. 4. GROUND + OUTPUT + SUPPLY - OUTPUT MILLIMETERS MIN MAX 15.11 16.00 13.06 13.56 5.08 5.59 0.41 0.51 1.22 1.63 2.54 BSC 0.36 0.40 17.65 18.42 30 _ NOM 12.07 12.57 10.92 11.43 BOTTOM CLAMP AREA Leads should be securely clamped top and bottom in the area between the plastic body and the form being sure that no stress is being put on plastic body. The area between dotted lines represents surfaces to be clamped. CASE 344-15 All seals to be made on pressure sealing surface. Figure 6. Chip-Carrier Package Motorola Sensor Device Data Figure 7. Leadforming www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-197 AN936 Freescale Semiconductor, Inc. Electrical Connection The MPX series pressure sensor is designed to be installed on a printed circuit board (standard 0.100 lead spacing) or to accept an appropriate connector if installed on a baseplate. The leads of the sensor may be formed at right angles for assembly to the circuit board, but one must ensure that proper leadform techniques and tools are employed. Hand or "needlenose" pliers should never be used for leadforming unless they are specifically designed for that purpose. Refer to Figure 7 for the recommended leadform technique. It is also important that once the leads are formed, they should not be straightened and reformed without expecting reduced durability. The recommended connector for off-circuit board applications may be supplied by JST Corp. (1-800-292-4243) in Mount Prospect, IL. The part numbers for the housing and pins are listed below. CONCLUSION Motorola's MPX series pressure sensors in the chip carrier package provide the design engineer several packaging alternatives. They can easily be tested with or without pressure ports using the information provided. Freescale Semiconductor, Inc... CONNECTORS FOR CHIP CARRIER PACKAGES MFG./ADDRESS/PHONE CONNECTOR PIN J.S. Terminal Corp. 1200 Business Center Dr. Mount Prospect, IL 60056 (800) 292-4243 4 Pin Housing: SMP-04V-BC 6 Pin Housing: SMP-06V-BC SHF-001T-0.8SS SHF-01T-0.8SS Methode Electronics, Inc. Rolling Meadows, IL 60008 (312) 392-3500 1300-004 Hand crimper YC-12 recommended Requires hand crimper 1400-213 1402-213 1402-214 Reel TERMINAL BLOCKS Molex 2222 Wellington Court Lisle, IL 60532 (312) 969-4550 22-18-2043 22-16-2041 Samtec P.O. Box 1147 New Albany, IN 47150 (812) 944-6733 SSW-104-02-G-S-RA SSW-104-02-G-S 3-198 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN936 A 0.002 0.175 0.001 0.01 x 45 4 PL For Vacuum or Pressure Source -A- 0.125 Dia. Freescale Semiconductor, Inc... 0.000 0.311 -0.001 Dia. 0.002 0.290 Dia. 0.070 Dia. 0.130 0.002 0.10 For Retaining Ring (Waldes Kohinoor Inc. Truarc 5100-31) EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE EEEEEEEEEEE 0.036 R 0.038 / A 0.002 TOTAL 30 0.44 Dia. 0.648 0.650 Dia. 0.575 Dia. 0.780 Dia. 0.002 0.670 Dia. 0.015 R 0.02 R 0.04 For O-Ring (Parker Seals 2-015-S469-40) 0.250 0.245 +0.003 -0.000 0.60 0.525- 1.00 1.25 Ref A 0.0005 Figure 8. O-Ring Test Fixture Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-199 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1082 Simple Design for a 4-20 mA Transmitter Interface Using a Motorola Pressure Sensor Prepared by: Jean Claude Hamelain Motorola Toulouse Application Lab Manager Freescale Semiconductor, Inc... INTRODUCTION Pressure is a very important parameter in most industrial applications such as air conditioning, liquid level sensing and flow control. In most cases, the sensor is located close to the measured source in a very noisy environment, far away from the receiver (recorder, computer, automatic controller, etc.) The transmission line can be as long as a few hundred meters and is subject to electromagnetic noise when the signal is transmitted as voltage. If the signal is transmitted as a current it is easier to recover at the receiving end and is less affected by the length of the transmission line. The purpose of this note is to describe a simple circuit which can achieve high performance, using standard Motorola pressure sensors, operational amplifiers and discrete devices. PERFORMANCES The following performances have been achieved using an MPXV2102DP Motorola pressure sensor and an MC33079 quad operational amplifier. The MPXV2102DP is a 100 kPa temperature compensated differential pressure sensor. The load is a 150 ohm resistor at the end of a 50 meter telephone line. The 15 volt power supply is connected at the receiver end. Power Supply +15 Vdc, 30 mA Connecting Line 3 wire telephone cable Load Resistance 150 to 400 Ohms Temperature Range - 40 to + 85C (up to +125C with special hardware) Pressure Range 0 to 100 kPa Total Maximum Error Better than 2% full scale Basic Circuit The Motorola MPXV2102DP pressure sensor is a very high performance piezoresistive pressure sensor. Manufacturing technologies include standard bipolar processing techniques with state of the art metallization and on-chip laser trim for offset and temperature compensation. This unique design, coupled with computer laser trimming, gives this device excellent performance at competitive cost for demanding applications such as automotive, industrial or healthcare. MC33078, 79 operational amplifiers are specially designed for very low input voltage, a high output voltage swing and very good stability versus temperature changes. First Stage The Motorola MPXV2102 and the operational amplifier are directly powered by the 15 Vdc source. The first stage is a simple true differential amplifier made with both of the operational amplifiers in the MC33078. The potentiometer, RG, provides adjustment for the output. Current Generator The voltage to current conversion is made with a unity gain differential amplifier, one of the four operational amplifiers in an MC33079. The two output connections from the first stage are connected to the input of this amplifier through R3 and R5. Good linearity is achieved by the matching between R3, R4, R5 and R6, providing a good common mode rejection. For the same reason, a good match between resistors R8 and R9 is needed. The MC33078 or MC33079 has a limited current output; therefore, a 2N2222 general purpose transistor is connected as the actual output current source to provide a 20 mA output. To achieve good performance with a very long transmission line it may be necessary to place some capacitors (C1, C2) between the power supply and output to prevent oscillations. Calibration The circuit is electrically connected to the 15 Vdc power supply and to the load resistor (receiver). The high pressure is connected to the pressure port and the low pressure (if using a differential pressure sensor), is connected to the vacuum port. It is important to perform the calibration with the actual transmission line connected. The circuit needs only two adjustments to achieve the 4 - 20 mA output current. 1. With no pressure (zero differential pressure), adjust Roff to read exactly 4 mA on the receiver. 2. Under the full scale pressure, adjust RG to exactly read 20 mA on the receiver. The calibration is now complete. REV 2 3-200 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1082 VCC = +15 Volts dc 3 RG 3 2 MPX2100DP 1 4 gain adj. + 8 a1 - R1 2 C1 C2 R4 1 R3 + + a3 - output 6 R2 - a2 7 + 4 5 - R5 Remote Receiver 2N2222 R8 RL R9 R7 R6 Roff R10 R11 Freescale Semiconductor, Inc... R12 OFFSET ADJUST Basic Circuit of SEK-1 RG = 47 K Pot. R7 = 1 K Roff = 1 M Pot. R10 = 110 K * R1 = R2 = 330 K R11 = 1 M * R3 = R4 = 27 K R12 = 330 K * R5 = R6 = 27 K C1 = C2 = 0.1 F * R8 = R9 = 150 a1, a2, a3 = 1/4 MC33079 * All resistor pairs must be matched at better than 0.5% Additional Circuit for 4 to 20 mA current loop (Receiver Load Resistance : RL = 150 to 400 Ohms) Note A: If using SEK-1 a1, a2, a3 = 1/2 MC33078 Note A: RG from 20 K to 47 K Note A: R1 and R2 from 1M to 330 K NOTICE: THE PRESSURE SENSOR OUTPUT IS RATIOMETRIC TO THE POWER SUPPLY VOLTAGE. THE OUTPUT WILL CHANGE WITH THE SAME RATIO AS VOLTAGE CHANGE. Figure 1. Demo Kit with 4 - 20 mA Current Loop The output is ratiometric to the power supply voltage. For example, if the receiver reads 18 mA at 80 kPa and 15 V power supply, the receiver should read 16.8 mA under the same pressure with 14 V power supply. For best results it is mandatory to use a regulated power supply. If that is not possible, the circuit must be modified by inserting a 12 V regulator to provide a constant supply to the pressure sensor. When using a Motorola MC78L12AC voltage regulator, the circuit can be used with power voltage variation from 14 to 30 volts. The following results have been achieved using an Motorola Sensor Device Data MPX2100DP and two MC33078s. The resistors were regular carbon resistors, but pairs were matched at 0.3% and capacitors were 0.1 F. The load was 150 ohms and the transmission line was a two pair telephone line with the +15 Vdc power supply connected on the remote receiver side. Note: Best performances in temperature can be achieved using metal film resistors. The two potentiometers must be chosen for high temperatures up to 125C. The complete circuit with pressure sensor is available under reference TZA120 and can be ordered as a regular Motorola product for evaluation. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-201 Freescale Semiconductor, Inc. AN1082 22 21 + 20 19 + + 18 + 17 16 Io (OUTPUT mA) 15 + 14 13 12 11 + 10 9 + 7 + 6 4 Power supply + 15 V dc, 150 Ohm load + 5 85 + 25 0 - 40 + 3 0 20 40 60 80 100 PRESSURE (kPa) Figure 2. Output versus Pressure 2.0 1.5 1.0 .5 ERROR (kPA) Freescale Semiconductor, Inc... 8 0 + + + + + + + + + + - .5 - 1.0 Reference algorithm Io(mA) = 4 + 16 x P(kPa) - 1.5 85 + 25 0 - 40 - 2.0 0 20 40 60 80 100 PRESSURE (kPa) Reference algorithm is the straight from output at 255 0 pressure and output at full pressure Figure 3. Absolute Error Reference to Algorithm 3-202 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Calibration-Free Pressure Sensor System AN1097 Prepared by: Michel Burri, Senior System Engineer Geneva, Switzerland Freescale Semiconductor, Inc... INTRODUCTION The MPX2000 series pressure transducers are semiconductor devices which give an electrical output signal proportional to the applied pressure. The sensors are a single monolithic silicon diaphragm with strain gauge and thin-film resistor networks on the chip. Each chip is laser trimmed for full scale output, offset, and temperature compensation. The purpose of this document is to describe another method of measurement which should facilitate the life of the designer. The MPX2000 series sensors are available both as unported elements and as ported assemblies suitable for pressure, vacuum and differential pressure measurements in the range of 10 kPa through 200 kPa. The use of the on-chip A/D converter of Motorola's MC68HC05B6 HCMOS MCU makes possible the design of an accurate and reliable pressure measurement system. SYSTEM ANALYSIS The measurement system is made up of the pressure sensor, the amplifiers, and the MCU. Each element in the chain has its own device-to-device variations and temperature effects which should be analyzed separately. For instance, the 8-bit A/D converter has a quantization error of about 0.2%. This error should be subtracted from the maximum error specified for the system to find the available error for the rest of elements in the chain. The MPX2000 series pressure sensors are designed to provide an output sensitivity of 4.0 mV/V excitation voltage with full-scale pressure applied or 20 mV at the excitation voltage of 5.0 Vdc. An interesting property must be considered to define the configuration of the system: the ratiometric function of both the A/D converter and the pressure sensor device. The ratiometric function of these elements makes all voltage variations from the power supply rejected by the system. With this advantage, it is possible to design a chain of amplification where the signal is conditioned in a different way. C CCC C CC CC C CC CC CCCC CC C CC C CC + Vs PIN 3 Rs1 Rp Rin THERMISTOR Rs2 LASER TRIMMED ON-CHIP PIN 1 PIN 2 + Vout - PIN 4 GND Figure 1. Seven Laser-Trimmed Resistors and Two Thermistors Calibrate the Sensor for Offset, Span, Symmetry and Temperature Compensation The op amp configuration should have a good common-mode rejection ratio to cancel the DC component voltage of the pressure sensor element which is about half the excitation voltage value VS. Also, the op amp configuration is important when the designer's objective is to minimize the calibration procedures which cost time and money and often don't allow the unit-to-unit replacement of devices or modules. One other aspect is that most of the applications are not affected by inaccuracy in the region 0 kPa thru 40 kPa. Therefore, the goal is to obtain an acceptable tolerance of the system from 40 kPa through 100 kPa, thus minimizing the inherent offset voltage of the pressure sensor. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-203 Freescale Semiconductor, Inc. AN1097 PRESSURE SENSOR CHARACTERISTICS OP AMP CHARACTERISTICS Figure 2 shows the differential output voltage of the MPX2100 series at +25C. The dispersion of the output voltage determines the best tolerance that the system may achieve without undertaking a calibration procedure, if any other elements or parameters in the chain do not introduce additional errors. For systems with only one power supply, the instrument amplifier configuration shown in Figure 4 is a good solution to monitor the output of a resistive transducer bridge. The instrument amplifier does provide an excellent CMRR and a symmetrical buffered high input impedance at both non-inverting and inverting terminals. It minimizes the number of the external passive components used to set the gain of the amplifier. Also, it is easy to compensate the temperature variation of the Full Scale Output of the Pressure Sensor by implementing resistors "Rf" having a negative coefficient temperature of -250 PPM/C. The differential-mode voltage gain of the instrument amplifier is: Vout (mV) 20 VS = 5 Vdc TA = 25C FULL-SCALE Freescale Semiconductor, Inc... 10 Avd = V1-V2 2 Rf = 1+ Vs2-Vs4 Rg (1) 5 OFFSET 0 +Vs -5 0 20 40 60 80 100 P (kPa) Figure 2. Spread of the Output Voltage versus the Applied Pressure at 25C The effects of temperature on the full scale output and offset are shown in Figure 3. It is interesting to notice that the offset variation is greater than the full scale output and both have a positive temperature coefficient respectively of +8.0 V/degree and +5.0 V excitation voltage. That means that the full scale variation may be compensated by modifying the gain somewhere in the chain amplifier by components arranged to produce a negative TC of 250 PPM/C. The dark area of Figure 3 shows the trend of the compensation which improves the full scale value over the temperature range. In the area of 40 kPa, the compensation acts in the ratio of 40/100 of the value of the offset temperature coefficient. Vout (f) T +85C POSITIVE FULL SCALE VARIATION -15C OFFSET VARIATION 0 20 40 60 80 100 + EEE EEEE EEEE EEE - 3 2 Rg 4 1 V1 Rf - + V2 0V Figure 4. One Power Supply to Excite the Bridge and to Develop a Differential Output Voltage The major source of errors introduced by the op amp is offset voltages which may be positive or negative, and the input bias current which develops a drop voltage V through the feedback resistance Rf. When the op amp input is composed of PNP transistors, the whole characteristic of the transfer function is shifted below the DC component voltage value set by the Pressure Sensor as shown in Figure 5. The gain of the instrument amplifier is calculated carefully to avoid a saturation of the output voltage, and to provide the maximum of differential output voltage available for the A/D Converter. The maximum output swing voltage of the amplifiers is also dependent on the bias current which creates a V voltage on the feedback resistance Rf and on the Full Scale output voltage of the pressure sensor. P (kPa) Figure 3. Output Voltage versus Temperature. The Dark Area Shows the Trend of the Compensation 3-204 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1097 lib (nA) V1, V2 5 Vdc VCC 600 450 UNIT 1 V1 V2X 1/2 VCC 0 5 150 V1X V2 VEE UNIT 2 300 10 15 20 0 VPS (mV) -50 -25 0 25 50 75 100 125 T (C) Freescale Semiconductor, Inc... Figure 7. Input Bias Current versus Temperature Figure 5. Instrument Amplifier Transfer Function with Spread of the Device to Device Offset Variation Figure 5 shows the transfer function of different instrument amplifiers used in the same application. The same sort of random errors are generated by crossing the inputs of the instrument amplifier. The spread of the differential output voltage (V1-V2) and (V2x-V1x) is due to the unsigned voltage offset and its absolute value. Figures 6 and 7 show the unit-to-unit variations of both the offset and the bias current of the dual op amp MC33078. MCU CONTRIBUTION As shown in Figure 5, crossing the instrument amplifier inputs generated their mutual differences which can be computed by the MCU. +VS + 3 2 Rg Vio (mV) 4 +2 V1 - 1 EE EE Rf - V2 + UNIT 1 P +1 0V UNIT 2 Figure 8. Crossing of the Instrument Amplifier Input Using a Port of the MCU 0 UNIT 3 -1 -2 -50 -25 0 25 50 75 100 125 T (C) Figure 6. Input Offset Voltage versus Temperature To realize such a system, the designer must provide a calibration procedure which is very time consuming. Some extra potentiometers must be implemented for setting both the offset and the Full Scale Output with a complex temperature compensation network circuit. The new proposed solution will reduce or eliminate any calibration procedure. Motorola Sensor Device Data Figure 8 shows the analog switches on the front of the instrument amplifier and the total symmetry of the chain. The residual resistance RDS(on) of the switches does not introduce errors due to the high input impedance of the instrument amplifier. With the aid of two analog switches, the MCU successively converts the output signals V1, V2. Four conversions are necessary to compute the final result. First, two conversions of V1 and V2 are executed and stored in the registers R1, R2. Then, the analog switches are commuted in the opposite position and the two last conversions of V2x and V1x are executed and stored in the registers R2x and R1x. Then, the MCU computes the following equation: RESULT = (R1 - R2) + (R2x - R1x) www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com (2) 3-205 Freescale Semiconductor, Inc. AN1097 The result is twice a differential conversion. As demonstrated below, all errors from the instrument amplifier are cancelled. Other averaging techniques may be used to EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE MC74HC4053 MPX2100AP 3 2 PRESSURE SENSOR SYSTEM Freescale Semiconductor, Inc... 4 1 improve the result, but the appropriated algorithm is always determined by the maximum bandwidth of the input signal and the required accuracy of the system. EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE +5V MC33078 + VRH CH1 - I/O Rf Rg MC68HC05B6 P Rf + - VDD V1 CH2 V2 VRL VSS 0V Figure 9. Two Channel Input and One Output Port Are Used by the MCU SYSTEM CALCULATION Sensor out 2 Vs2 = a (P) + of2 Sensor out 4 Vs4 = b (P) + of4 Amplifier out 1 V1 = Avd (Vs2 + OF1) Amplifier out 2 V2 = Avd (Vs4 + OF2) Inverting of the amplifier input V1x = Avd (Vs4 + OF1) V2x = Avd (Vs2 + OF2) Delta = V1-V2 1st differential result = Avd * (Vs2 of OF1) - Avd * (Vs4 + OF2) Deltax = V2x-V1x 2nd differential result = Avd * (Vs2 + OF2) - Vdc * (Vs4 + OF1) Adding of the two differential results VoutV = Delta + Deltax = Avd*Vs2 + Avd*OF2 + Avd*OF2 - Avd*OF1 + Avd*OF1 - Avd*OF2 + Avd*OF2 - Avd*OF1 = 2 * Avd * (Vs2 -Vs4) = 2 * Avd * [(a (P) + of2) - (b (P) + of4)] = 2 * Avd * [V(P) + Voffset] neglected. That means the system does not require any calibration procedure. The equation of the system transfer is then: count = 2 * Avd * V(P) * 51/V where: Avd is the differential-mode gain of the instrument amplifier which is calculated using the equation (1). Then with Rf = 510 k and Rg = 9.1 k Avd = 113. The maximum counts available in the MCU register at the Full Scale Pressure is: count (Full Scale) = 2 * 113 * 0.02 V * 51/V = 230 knowing that the MPX2100AP pressure sensor provides 20 mV at 5.0 excitation voltage and 100 kPa full scale pressure. The system resolution is 100 kPa/230 that give 0.43 kPa per count. +5V VDD There is a full cancellation of the amplifier offset OF1 and OF2. The addition of the two differential results V1-V2 and V2x-V1X produce a virtual output voltage VoutV which becomes the applied input voltage to the A/D converter. The result of the conversion is expressed in the number of counts or bits by the ratiometric formula shown below: count = VoutV * VRH I/O CH1 MC68HC05B6 P CH2 255 VRH-VRL 255 is the maximum number of counts provided by the A/D converter and VRH-VRL is the reference voltage of the ratiometric A/D converter which is commonly tied to the 5.0 V supply voltage of the MCU. When the tolerance of the full scale pressure has to be in the range of 2.5%, the offset of the pressure sensor may be 3-206 FINE CAL. VRL VSS 0V Figure 10. Full Scale Output Calibration Using the Reference Voltage VRH-VRL www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. When the tolerance of the system has to be in the range of 1%, the designer should provide only one calibration EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE MC74HC4053 MPX2100AP 3 2 Freescale Semiconductor, Inc... 4 1 PRESSURE SENSOR SYSTEM AN1097 procedure which sets the Full Scale Output (counts) at 25C 100 kPa or under the local atmospheric pressure conditions. EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE EEEEE +5V MC33078 + EEE EEE EEE EEE - Rf Rg Rf - + VRH 1/3 MC74HC4053 V1 VDD P1 I/O MC68HC05B6 CH1 P2 V2 VRL VSS 0V Figure 11. One Channel Input and Two Output Ports are used by the MCU Due to the high impedance input of the A/D converter of the MC68HC05B6 MCU, another configuration may be implemented which uses only one channel input as shown in Figure 11. It is interesting to notice that practically any dual op amp may be used to do the job but a global consideration must be made to optimize the total cost of the system according the the requested specification. When the Full Scale Pressure has to be sent with accuracy, the calibration procedure may be executed in different ways. For instance, the module may be calibrated directly using Up/Down push buttons. The gain of the chain is set by changing the VRH voltage of the ratiometric A/D converter with the R/2R ladder network circuit which is directly drived by the ports of the MCU. (See Figure 12.) Using a communication bus, the calibration procedure may be executed from a host computer. In both cases, the setting value is stored in the EEROM of the MCU. The gain may be also set using a potentiometer in place of the resistor Rf. But, this component is expensive, taking into account that it must be stable over the temperature range at long term. +5V 2R RO VDD VRH I/O 2R P3 R R/2R LADDER R NETWORK R 2R P2 BUS MC68HC05B6 2R P1 +5V 2R P0 CH1 CH2 VRL VSS UP DOWN 0V Figure 12. Table 1. Pressure Conversion Table Unity Pa mbar Torr atm at=kp/cm2 mWS psi 1 N/m2 = 1 Pascal 1 0.01 7.5 10-3 -- -- -- -- 100 1 0.75 -- -- 0.0102 0.014 1 Torr = 1 mmHg 133.32 1.333 .1 -- -- -- 0.019 1 atm (1) 101325 1013.2 760 1 1.033 10.33 14.69 1 at = 1 kp/cm2 (2) 98066.5 981 735.6 0.97 1 10 14.22 1 m of water 9806.65 98.1 73.56 0.097 0.1 1 1.422 1 lb/sqin = 1 psi 6894.8 68.95 51.71 0.068 -- -- 1 1 mbar (1) Normal atmosphere (2) Technical atmosphere Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-207 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1100 Analog to Digital Converter Resolution Extension Using a Motorola Pressure Sensor PURPOSE Freescale Semiconductor, Inc... This paper describes a simple method to gain more than 8-bits of resolution with an 8-bit A/D. The electronic design is relatively simple and uses standard components. Refer to Figure 1 and assume a pressure of 124 kPa is to be measured. With this system, the input signal to the A/D should read (assuming no offset voltage error): V m(measured) PRINCIPLE Consider a requirement to measure pressure up to 200 kPa. Using a pressure sensor and an amplifier, this pressure can be converted to an analog voltage output. This analog voltage can then be converted to a digital value and used by the microprocessor as shown in Figure 1. If we assume for this circuit that 200 kPa results in a +4.5 V output, the sensitivity of our system is:/ + 4.5 V200kPa + 0.0225 VkPa S + 22.5 mVkPa (1) S or + 5V + 0.01961 V R v + 19.60 mV per bit S or + 5V255 2 8-1 (2) M (5) + (142 count) x 19.60mV count) + 2783 mV (6) The microprocessor will output the stored value M to the D/A. The corresponding voltage at the analog output of the D/A, for an 8-bit D/A with same references, will be 2783 mV. The calculated pressure corresponding to this voltage would be: P c (calculated) + 5V 19.60 mVbit) 22.5 mVkPa + 0.871 kPa per bit + (2790 mV) 19.60 mVbit + 142.35 + 142 (truncated to integer) The calculated voltage for this stored value is: This corresponds to a pressure resolution of: RP (4) where Papp is the pressure applied to the sensor. Due to the resolution of the A/D, the microprocessor receives the following conversion: V c (calculated) If an 8-bit A/D is used with 0 and 5 Volt low and high references, respectively, then the resolution would be: + 4.5 (Papp) x (S) + (124 kPa) x 22.5 mVkPa + 2790 mV, + (2783 mV) 22.5 mVkPa (7) 123.7 kPa (3) Thus, the error would be: E Assume a resolution of at least 0.1 kPa/bit is needed. This would require an A/D with at least 12 bits ( 212 = 4096 steps). One can artificially increase the A/D resolution as described below. + Papp-Pc + 124 kPa-123.7 kPa + 0.3 kPa (8) This is greater than the 0.1 kPa resolution requirement. +V G Vm A/D M MPU Pc OUTPUT CIRCUITRY Figure 1. Block Diagram REV 1 3-208 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1100 +V Vm M G A/D C D G - Control OUTPUT CIRCUITRY MPU Vc M Freescale Semiconductor, Inc... D/A ANALOG CIRCUITRY Figure 2. Expanded Block Diagram Figure 2 shows the block diagram of a system that can be used to reduce the inaccuracies caused by the limited A/D resolution. The microprocessor would use the stored value M, as described above, to cause a D/A to output the corresponding voltage, Vc. Vc is subtracted from the measured voltage, Vm, using a differential amplifier, and the resulting voltage is amplified. Assuming a gain, G, of 10 for the amplifier, the output would be: D + (Vm-Vc) G + (2790 mV-2783 mV) + 70 mV (9) Expanded Voltage + 70mV19.60 mVcount + 3.6 + 3 full counts + Vc ) C R) G) + 2783 ) 3 19.60)10) + 2789 mV, (11) NOTE: R is resolution of 8-bit d/A Corresponding Pressure 10 The microprocessor will receive the following count from the A/D: C The microprocessor then computes the actual pressure with the following equations: Thus the error is: Pressure Error (10) + 2789 mV + 22.5 mVkPa + 123.9 kPa + Actual - Measured + 124 kPa - 123.9 kPa + 0.1 kPa (12) (13) Figures 3 and 4 together provide a more detailed description of the analog portion of this system. +V R4 R3 +V R2 R5 + R1 R8 A1 + - A2 R6 R7 Note: R7 = R2, R1 = R6 Vm (to Second Stage) - R9 R10 Figure 3. First Stage - Differential Amplifier, Offset Adjust and Gain Adjust Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-209 Freescale Semiconductor, Inc. AN1100 Vm R11 Vm (from first stage) + R15 A3 R12 + - R14 R16 R17 R13 Note: R14 = R12, R11 = R13 D A4 - Freescale Semiconductor, Inc... from D/A Vc Figure 4. Second Stage -- Difference Amplifier and Gain FIRST STAGE (Figure 3) The first stage consists of the Motorola pressure sensor; in this case the MPX2200 is used. This sensor typically gives a full scale span output of 40 mV at 200 kPa. The sensor output (VS) is connected to the inputs of amplifier A1 (1/4 of the MC33079, a Quad Operational Amplifier). The gain, G1, of this amplifier is R7/R6. The sensor has a typical zero pressure offset voltage of 1 mV. Figure 3 shows offset compensation circuitry if it is needed. A1 output is fed to the non-inverting input of A2 amplifier (1/4 of a MC33079) whose gain, G2, is 1+R10/R9. G2 should be set to yield 4.5 volts out with full-rated pressure. The theoretical resolution is limited only by the accuracy of the programmable power supply. The Motorola microprocessor used has an integrated A/D. The accuracy of this A/D is directly related to the reference voltage source stability, which can be self-calibrated by the microprocessor. Vexpanded is the system output that is the sum of the voltage due to the count and the voltage due to the difference between the count voltage and the measured voltage. This is given by the following relation: + Vc ) DG3 PV expanded + V expandedS. V expanded therefore, THE SECOND STAGE (Figure 4) The output from A2 (Vm = G1 x G2 x Vs) is connected to the non-inverting input of amplifier A3 (1/4 of a MC33079) and to the A/D where its corresponding (digital) value is stored by the microprocessor. The output of A3 is the amplified difference between Vm, and the digitized/calculated voltage Vc. Amplifier A4 (1/4 of a MC33079) provides additional gain for an amplified difference output for the desired resolution. This difference output, D, is given by: + Vm - Vc G3 G3 + R14 R13 1 ) R17 R16 D Pexpanded is the value of pressure (in units of kPa) that results from this improved-resolution system. This value can be output to a display or used for further processing in a control system. CONCLUSION This circuit provides an easy way to have high resolution using inexpensive microprocessors and converters. where G3 is the gain associated with amplifiers A3 and A4. 3-210 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR APPLICATION NOTE A Simple 4-20 mA Pressure Transducer Evaluation Board AN1303 Prepared by: Denise Williams Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION The two wire 4 - 20 mA current loop is one of the most widely utilized transmission signals for use with transducers in industrial applications. A two wire transmitter allows signal and power to be supplied on a single wire-pair. Because the information is transmitted as current, the signal is relatively immune to voltage drops from long runs and noise from motors, relays, switches and industrial equipment. The use of additional power sources is not desirable because the usefulness of this system is greatest when a signal has to be transmitted over a long distance with the sensor at a remote location. Therefore, the 4 mA minimum current in the loop is the maximum usable current to power the entire control circuitry. Figure 1 is a block diagram of a typical 4 - 20 mA current loop system which illustrates a simple two chip solution to converting pressure to a 4 - 20 mA signal. This system is designed to be powered with a 24 Vdc supply. Pressure is converted to a differential voltage by the Motorola MPX5100 pressure sensor. The voltage signal proportional to the monitored pressure is then converted to the 4 - 20 mA current signal with the Burr-Brown XTR101 Precision Two-Wire Transmitter. The current signal can be monitored by a meter in series with the supply or by measuring the voltage drop across RL. A key advantage to this system is that circuit performance is not affected by a long transmission line. SENSOR PRESSURE PORT PRESSURE SOURCE PRESSURE SENSOR TRANSMITTER CIRCUITRY AAAA AA AA AAAA AA AA TRANSMISSION LINE 4 - 20 mA PRESSURE TRANSDUCER 24 VDC RL CURRENT METER Figure 1. System Block Diagram REV 4 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-211 Freescale Semiconductor, Inc. AN1303 INPUT TERMINALS A schematic of the 4 - 20 mA Pressure Transducer topology is shown in Figure 2. Connections to this topology are made at the terminals labeled (+) and (-). Because this system utilizes a current signal, the power supply, the load and any current meter must be put in series with the (+) to (-) terminals as indicated in the block diagram. The load for this type of system is typically a few hundred ohms. As described above, a typical use of a 4 - 20 mA current transmission signal is the transfer of information over long distances. Therefore, a long transmission line can be connected between the (+) and (-) terminals on the evaluation board and the power supply/load. 2 mA 3 2 10 11 Freescale Semiconductor, Inc... XDCR1 MPX7100 D2 1N4565A 6.4V @ 0.5mA R3 39 4 1 R5 50 4 5 U1 XTR101 6 3 R6 100K R2 1K 12 1 2 14 7 13 + 4 - 20 mA OUTPUT R1 750 1/2 W 8 D1 1N4002 Q1 MPSA06 C1 0.01F 9 - RETURN R4 1M 4 - 20 mA PRESSURE TRANSDUCER Figure 2. Schematic Diagram PRESSURE INPUT The device supplied on this topology is an MPX5100DP, which provides two ports. P1, the positive pressure port, is on top of the sensor and P2, the vacuum port, is on the bottom of the sensor. The system can be supplied up to 15 PSI of positive pressure to P1 or up to 15 PSI of vacuum to P2 or a differential pressure up to 15 PSI between P1 and P2. Any of these pressure applications will create the same results at the sensor output. CIRCUIT DESCRIPTION The XTR101 current transmitter provides two one-milliamp current sources for sensor excitation when its bias voltage is between 12 V and 40 V. The MPX5100 series sensors are constant voltage devices, so a zener, D2, is placed in parallel with the sensor input terminals. Because the MPX5100 series parts have a high impedance the zener and sensor combination can be biased with just the two milliamps available from the XTR101. The offset adjustment is composed of R4 and R6. They are used to remove the offset voltage at the differential inputs to the XTR101. R6 is set so a zero input pressure will result in the desired output of 4 mA. R3 and R5 are used to provide the full scale current span of 16 mA. R5 is set such that a 15 PSI input pressure results in the desired output of 20 mA. Thus the current signal will span 3-212 16 mA from the zero pressure output of 4 mA to the full scale output of 20 mA. To calculate the resistor required to set the full scale output span, the input voltage span must be defined. The full scale output span of the sensor is 24.8 mV and is VIN to the XTR101. Burr-Brown specifies the following equation for Rspan. The 40 and 16 m values are parameters of the XTR101. R span + 40 16 mA DVin) * 0.016 mhos] + 64 W The XTR101 requires that the differential input voltage at pins 3 and 4, V2 - V1 be less than 1V and that V2 (pin 4) always be greater than V1 (pin 3). Furthermore, this differential voltage is required to have a common mode of 4-6 volts above the reference (pin 7). The sensor produces the differential output with a common mode of approximately 3.1 volts above its reference pin 1. Because the current of both 1 mA sources will go through R2, a total common mode voltage of about 5.1 volts (1 k x 2 mA + 3.1 volts = 5.1 volts) is provided. CONCLUSION This circuit is an example of how the MPX5000 series sensors can be utilized in an industrial application. It provides a simple design alternative where remote pressure sensing is required. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1303 Table 1. Parts List for 4 - 20 mA Pressure Transducer Evaluation Board Freescale Semiconductor, Inc... Designator Quantity Description 1 1 4 4 2 2 PC Board (see Figure 3) Input/Output Terminals 1/2 standoffs, Nylon threaded 1/2 screws, Nylon 5/8 screws, Nylon 4-40 nuts, Nylon C1 1 Capacitor 0.01 F D1 D2 1 1 Diodes 100 V Diode 6.4 V Zener Q1 1 Transistor NPN Bipolar R1 R2 R3 R4 1 1 1 1 Resistors, Fixed 750 1 k 39 1 M R5 R6 1 1 U1 XDCR1 Rating Manufacturer Motorola PHX CONT Part Number DEVB126 #1727010 50 V 1A 1N4002 1N4565A Motorola MPSA06 Resistors, Variable 50 , one turn 100 K, one turn Bourns Bourns #3386P-1-500 #3386P-1-104 1 Integrated Circuit Two wire current transmitter Burr-Brown XTR101 1 Sensor High Impedance Motorola MPX5100DP 1/2 W 15 PSI NOTE: All resistors are 1/4 W with a tolerance of 5% unless otherwise noted. All capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-213 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Integrated Sensor Simplifies Bar Graph Pressure Gauge AN1304 Prepared by: Warren Schultz Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Integrated semiconductor pressure sensors such as the MPX5100 greatly simplify electronic measurement of pressure. These devices translate pressure into a 0.5 to 4.5 volt output range that is designed to be directly compatible with microcomputer A/D inputs. The 0.5 to 4.5 volt range also facilitates interface with ICs such as the LM3914, making Bar Graph Pressure Gauges relatively simple. A description of a Bar Graph Pressure Sensor Evaluation Board and its design considerations are presented here. Figure 1. DEVB129 MPX5100 Bar Graph Pressure Gauge (Board No Longer Available) REV 1 3-214 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1304 EVALUATION BOARD DESCRIPTION Freescale Semiconductor, Inc... A summary of the information required to use evaluation board number DEVB129 is presented as follows. A discussion of the design appears under the heading Design Considerations. FUNCTION The evaluation board shown in Figure 1 is designed to provide a 100 kPa full scale pressure measurement. It has two input ports. P1, the pressure port is on the top side of the MPX5100 sensor, and P2, a vacuum port, is on the bottom side. These ports can be supplied up to 100 kPa (15 psi)* of pressure on P1 or up to 100 kPa of vacuum on P2, or a differential pressure up to 100 kPa between P1 and P2. Any of these sources will produce the same output. The primary output is a 10 segment LED bar graph, which is labeled in increments of 10 kPa. If full scale pressure is adjusted for a value other than 100 kPa the bar graph may be read as a percent of full scale. An analog output is also provided. It nominally supplies 0.5 volts at zero pressure and 4.5 volts at 100 kPa. Zero and full scale adjustments are made with potentiometers so labeled at the bottom of the board. Both adjustments are independent of each other. ELECTRICAL CHARACTERISTICS The following electrical characteristics are included to describe evaluation board operation. They are not specifications in the usual sense and are intended only as a guide to operation. Characteristic Symbol Min Typ Max Units Power Supply Voltage B+ 6.8 -- 13.2 Volts PFS -- -- 100 kPa PMAX -- -- 700 kPa VFS -- 4.5 -- Volts VOFF -- 0.5 -- Volts Analog Sensitivity SAOUT -- 40 -- mV/kPa Quiescent Current ICC -- 20 -- mA Full Scale Current IFS -- 140 -- mA Full Scale Pressure Overpressure Analog Full Scale Analog Zero Pressure Offset PIN-BY-PIN DESCRIPTION B+: Input power is supplied at the B+ terminal. Minimum input voltage is 6.8 volts and maximum is 13.2 volts. The upper limit is based upon power dissipation in the LM3914 assuming all 10 LED's are lit and ambient temperature is 25C. The board will survive input transients up to 25 volts provided that power dissipation in the LM3914 does not exceed 1.3 watts. OUT: An analog output is supplied at the OUT terminal. The signal it provides is nominally 0.5 volts at zero pressure and 4.5 volts at 100 kPa. This output is capable of sourcing 100 A at full scale output. GND: There are two ground connections. The ground terminal on the left side of the board is intended for use as the power supply return. On the right side of the board, one of the test point terminals is also connected to ground. It provides a convenient place to connect instrumentation grounds. TP1: Test point 1 is connected to the zero pressure reference voltage and can be used for zero pressure calibration. To calibrate for zero pressure, this voltage is adjusted with R6 to match the zero pressure voltage that is measured at the analog output (OUT) terminal. TP2: Test point 2 performs a similar function at full scale. It is connected to the LM3914's reference voltage which sets the trip point for the uppermost LED segment. This voltage is adjusted via R5 to set full scale pressure. P1, P2: Pressure and Vacuum ports P1 & P2 protrude from the MPX5100 sensor on the right side of the board. Pressure port P1 is on the top and vacuum port P2 is on the bottom. Neither is labeled. Either one or a differential pressure applied to both can be used to obtain full scale readings up to 100 kPa (15 psi). Maximum safe pressure is 700 kPa. CONTENT Board contents are described in the following parts list, schematic, and silk screen plot. A pin by pin circuit description follows in the next section. * 100 kPa = 14.7 psi, 15 psi is used throughout the text for convenience Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-215 Freescale Semiconductor, Inc. AN1304 DESIGN CONSIDERATIONS Freescale Semiconductor, Inc... In this type of an application the design challenge is how to interface a sensor with the bar graph output. MPX5100 Sensors and LM3914 Bar Graph Display drivers fit together so cleanly that having selected these two devices the rest of the design is quite straight forward. A block diagram that appears in Figure 4 shows the LM3914's internal architecture. Since the lower resistor in the input comparator chain is pinned out at RLO, it is a simple matter to tie this pin to a voltage that is approximately equal to the MPX5100's zero pressure output voltage. In Figure 2, this is accomplished by dividing down the 5 volt regulator's output voltage through R1, R4, and adjustment pot R6. The voltage generated at the wiper of R6 is then fed into RLO which matches the sensor's zero pressure voltage and zeros the bar graph. The full scale measurement is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. An internal regulator on the LM3914 sets this voltage with the aid of resistors R2, R3, and adjustment pot R5 that are shown in Figure 2. The MPX5100 requires 5 volt regulated power that is supplied by an MC78L05. The LED's are powered directly from LM3914 outputs, which are set up as current sources. Output current to each LED is approximately 10 times the reference current that flows from pin 7 through R2, R5, and R3 to ground. In this design it is nominally (4.5 V/4.9K)10 = 9.2 mA. Over a zero to 85C temperature range accuracy for both the sensor and driver IC are 2.5%, totaling 5%. Given a 10 segment display total accuracy is approximately (10 kPa +5%). CONCLUSION Perhaps the most noteworthy aspect to the bar graph pressure gauge described here is how easy it is to design. The interface between an MPX5100 sensor, LM3914 display driver, and bar graph output is direct and straight forward. The result is a simple circuit that is capable of measuring pressure, vacuum, or differential pressure; and will also send an analog signal to other control circuitry. S1 +12 V D1 ON/OFF D2 D3 D4 D5 D6 D7 D8 D9 D10 C2 1 F U3 3 I MC78L05ACP U1 C1 0.1 F O 1 R4 G 2 1.3K 3 1 2 GND 1 2 3 4 5 6 7 8 9 U2 MPX5100 ZERO CAL. LED GND B+ RLO SIG RHI REF ADJ MOD R2 1.2 k R6 100 R1 100 LED LED LED LED LED LED LED LED LED 18 17 16 15 14 13 12 11 10 LM3914 R5 1k TP2 (FULL SCALE CALIBRATION) TP1 (ZERO CALIBRATION) GND FULL SCALE CALIBRATION R3 2.7 k ANALOG OUT Figure 2. MPX5100 Pressure Gauge 3-216 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1304 MPX5100 PRESSURE GAUGE MOTOROLA DISCRETE APPLICATIONS PRESSURE kPa 100 90 70 60 LM3914 MV57164 80 50 MPX5100 40 30 Freescale Semiconductor, Inc... 20 C2 10 C1 B+ TP2 R3 U3 OUT TP1 R2 GND ON DEVB129 R6 GND R5 OFF ZERO FULL SCALE Figure 3. Silk Screen 2X Table 1. Parts List Designators Quant. Description Rating Manufacturer Part Number 0.1 F 1 F C1 C2 1 1 Ceramic Cap Ceramic Cap D1-D10 1 Bar Graph LED R1 R2 R3 R4 R5 R6 1 1 1 1 1 1 1/4 W Film Resistor 1/4 W Film Resistor 1/4 W Film Resistor 1/4 W Film Resistor Trimpot Trimpot S1 1 On/Off Switch NKK 12SDP2 U1 U2 U3 1 1 1 Bar Graph IC Pressure Sensor Voltage Regulator National Motorola Motorola LM3914 MPX5100 MC78L05ACP -- -- -- -- 1 3 4 4 Terminal Block Test Point Terminal Nylon Spacer 4-40 Nylon Screw Augat Components Corp. 25V03 TP1040104 GI 100 1.2K 2.7K 1.3K 1K 100 MV57164 Bourns Bourns 3/8 1/4 Note: All resistors have a tolerance of 5% unless otherwise noted. Note: All capacitors are 50 volt ceramic capacitors with a tolerance of 10% unless otherwise noted. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-217 Freescale Semiconductor, Inc. AN1304 LED V+ LM3914 RHI Freescale Semiconductor, Inc... REF OUT 6 7 + THIS LOAD DETERMINES LED BRIGHTNESS REF ADJ V+ - + REFERENCE VOLTAGE SOURCE 1.25 V - 8 3 1k - + 11 1k - + 12 1k - + 13 1k - + 14 - + 15 - + 16 1k - + 17 1k - + 18 1k - + 1 1k 1k 1k RLO COMPARATOR 1 of 10 10 V+ FROM PIN 11 4 MODE SELECT AMPLIFIER 9 - BUFFER SIG IN 5 CONTROLS TYPE OF DISPLAY, BAR OR SINGLE LED 2 V- 20 k + Figure 4. LM3914 Block Diagram 3-218 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE An Evaluation System for Direct Interface of the MPX5100 Pressure Sensor with a Microprocessor AN1305 Prepared by: Bill Lucas Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Interfacing pressure sensors to analog-to-digital converters or microprocessors with on-chip A/D converters has been a challenge that most engineers do not enjoy accepting. Recent design advances in pressure sensing technology have allowed the engineer to directly interface a pressure sensor to an A/D converter with no additional active components. This has been made possible by integrating a temperature compensated pressure sensor element and active linear circuitry on the same die. A description of an evaluation board that shows the ease of interfacing a signal conditioned pressure sensor to an A/D converter is presented here. Figure 1. DEVB-114 MPX5100 Evaluation Module (Board No Longer Available) REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-219 Freescale Semiconductor, Inc. AN1305 offset. The sensor's zero offset voltage with no pressure applied to the sensor is empirically computed each time power is applied to the system and stored in RAM. The sensitivity of the MPX5100 is repeatable from unit to unit. There is a facility for a small "rubbering" of the slope constant built into the program. It is accomplished with jumpers J1 and J2, and is explained in the Operation section. The board contents are further described in the schematic, silk screen plot, and parts list that appear in Figures 2, 3 and Table 1. PURPOSE This evaluation system, shown in Figure 1, demonstrates the ease of operation and interfacing of the Motorola MPX5100 series pressure sensors with on-chip temperature compensation, calibration and amplification. The board may be used to evaluate the sensor's suitability for a specific application. DESCRIPTION BASIC CIRCUIT Freescale Semiconductor, Inc... The DEVB-114 evaluation board is constructed on a small printed circuit board. It is powered from a single +5 Vdc regulated power supply. The system will display the pressure applied to the MPX5100 sensor in pounds per square inch. The range is 0 PSI through 15 PSI, resolved to 0.1 PSI. No potentiometers are used in the system to adjust the span and The evaluation board consists of three basic subsystems: an MPX5100GP pressure sensor, a four digit liquid crystal display (only three digits and a decimal are used) and a programmed microprocessor with the necessary external circuitry to support the operation of the microprocessor. LCD LIQUID CRYSTAL DISPLAY IEE PART NUMBER LCD5657 OR EQUAL BP 28 37 36 5 6 7 34 35 8 49 0 31 32 9 10 11 29 30 12 47 48 42 43 44 45 46 2 1 7 6 5 4 3 26 27 13 14 15 24 25 16 22 23 17 37 38 32 33 34 35 36 2 1 7 6 5 4 3 31 0 29 30 24 25 26 27 28 2 1 7 6 5 4 3 PORTC PORTB 18 19 20 21 1-4, 33 39, 38, 40 +5 PORTA R5 52 U1 VRH TD0 8 15 OHM 1% 4.85 V MC68HC705B5FN 50 44 R6 RDI VSS VRL OSC1 16 OSC2 17 PD5 5 PD6 PD7 4 3 4 MHz Y1 R3 10K 22 pF C4 R2 10MEG J1 4.7K ______ RESET 18 PD4 PD3 PD1 VPP6 VDD PD2 PD0 9 10 11 12 13 14 15 RESET TCAP1 D/A TCAP2 21 22 23 .302 V R7 30.1 OHM 1% +5 R1 10K R4 22 pF C3 ___ IRQ 19 7 453 OHM 1% +5 U2 IN 34064P- 5 J2 +5 +5 J3 GND + C1 100 F +5 .1 VCC C2 OUT XDCR1 MPX5100 GND Figure 2. DEVB-114 System Schematic 3-220 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1305 Table 1. DEVB-114 Parts List Freescale Semiconductor, Inc... Designators Quant. Description Rating Manufacturer Part Number C1 1 100 F Electrolytic Capacitor 25 Vdc Sprague 513D107M025BB4 C2 1 0.1 F Ceramic Capacitor 50 Vdc Sprague 1C105Z5U104M050B C3, C4 2 22 pF Ceramic Capacitor 100 Vdc Mepco/Centralab CN15A220K J1, J2 1 Dual Row Straight .025 Pins Arranged On .1 Grid Molex 10-89-1043 AMPEREX LTD226R-12 LCD 1 Liquid Crystal Display R1 1 4.7 k Ohm Resistor R2 1 10 Meg Ohm Resistor R3, R4 2 10 k Ohm Resistor R5 1 15 Ohm 1% 1/4 W Resistor R6 1 453 Ohm 1% 1/4 W Resistor R7 1 30.1 Ohm 1% 1/4 W Resistor XDCR1 1 Pressure Sensor Motorola MPX5100GP U1 1 Microprocessor Motorola Motorola MC68HC705B5FN or XC68HC705B5FN U2 1 Under Voltage Detector Motorola MC34064P-5 Y1 1 Crystal (Low Profile) ECS ECS-40-S-4 No Designator 1 52 Pin PLCC Socket AMP 821-575-1 No Designator 2 Jumpers For J1 and J2 Molex 15-29-1025 No Designator 1 Bare Printed Circuit Board 4.0 MHz Note: All resistors are 1/4 W resistors with a tolerance of 5% unless otherwise noted. Note: All capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted. LCD1 U1 J1 J2 R3 R4 R5 R6 R7 R1 C2 C3 C1 GND J3 U2 C4 Y1 VCC R2 XDRC OUT 1 GND TP1 TP2 TP3 +5 XDRC1 DEVB-114 REV. 0 Figure 3. Silk Screen Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-221 Freescale Semiconductor, Inc. AN1305 Theory of Operation Referring to the schematic, Figure 2, the MPX5100 pressure sensor is connected to PORT D bit 5 of the microprocessor. This port is an input to the on-chip 8 bit analog to digital converter. The pressure sensor provides a signal output to the microprocessor of approximately 0.5 Vdc at 0 psi to 4.5 Vdc at 15 psi of applied pressure as shown in Figure 4. The input range of the A to D converter is set at approximately 0.3 Vdc to 4.85 Vdc. This compresses the range of the A to D converter around the output range of the sensor to maximize the A to D converter resolution; 0 to 255 counts is the range of the A to D converter. VRH and VRL are the reference voltage inputs to the A to D converter. The resolution is defined by the following: Analog-to-digital converter count = The count at 0 psi = [(.5 - .302)/(4.85 - .302)] * 255 11 The count at 15 psi = [(4.5 - .302)/(4.85 - .302)] * 255 235 Therefore the resolution = count @ 15 psi - count @ 0 psi or the resolution is (235 - 11) = 224 counts. This translates to a system that will resolve to 0.1 psi. VS = 5.0 Vdc TA = 25C MPX5100 4.5 OUTPUT (Vdc) Freescale Semiconductor, Inc... [(Vxdcr - VRL)/(VRH - VRL)] * 255 TYP MIN TYP SPAN MAX The microprocessor section of the system requires certain support hardware to allow it to function. The MC34064P-5 (U2) provides an under voltage sense function which is used to reset the microprocessor at system power-up. The 4 MHz crystal (Y1) provides the external portion of the oscillator function for clocking the microprocessor and provides a stable base for time based functions. Jumpers J1 and J2 are examined by the software and are used to "rubber" the slope constant. OPERATION The system must be connected to a 5 Vdc regulated power supply. Note the polarity marked on the power terminal J3. Jumpers J1 and J2 must either both be installed or both be removed for the normal slope constant to be used. The pressure port on the MPX5100 sensor must be left open to atmosphere anytime the board is powered-up. As previously stated, the sensor's voltage offset with zero pressure applied is computed at power-up. You will need to apply power to the system. The LCD will display CAL for approximately 5 seconds. After that time, the LCD will then start displaying pressure. To improve upon the accuracy of the system, you can change the constant used by the program that constitutes the span of the sensor. You will need an accurate test gauge to measure the pressure applied to the sensor. Anytime after the display has completed the zero calculation (after CAL is no longer displayed), apply 15.0 PSI to the sensor. Make sure that jumpers J1 and J2 are either both installed or both removed. Referring to Table 2, you can increase the displayed value by installing J1 and removing J2. Conversely, you can decrease the displayed value by installing J2 and removing J1. J1 J2 IN OUT OUT IN OUT IN IN OUT 0.5 TYP OFFSET 0 0 kPa PSI 25 50 75 100 3.62 7.25 10.87 14.5 Action USE NORMAL SPAN CONSTANT USE NORMAL SPAN CONSTANT DECREASE SPAN CONSTANT APPROXIMATELY 1.5% INCREASE SPAN CONSTANT APPROXIMATELY 1.5% Table 2. Figure 4. MPX5100 Output versus Pressure Input SOFTWARE The voltage divider consisting of R5 through R7 is connected to the +5 volts powering the system. The output of the pressure sensor is ratiometric to the voltage applied to it. The pressure sensor and the voltage divider are connected to a common supply; this yields a system that is ratiometric. By nature of this ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. The liquid crystal display is directly driven from I/O ports A, B, and C on the microprocessor. The operation of a liquid crystal display requires that the data and backplane pins must be driven by an alternating signal. This function is provided by a software routine that toggles the data and backplane at approximately a 30 Hz rate. 3-222 The source code, compiler listing, and S-record output for the software used in this system are available on the Motorola Freeware Bulletin Board Service in the MCU directory under the filename DEVB-114.ARC. To access the bulletin board you must have a telephone line, a 300, 1200 or 2400 baud modem and a terminal or personal computer. The modem must be compatible with the Bell 212A standard. Call 1-512-891-3733 to access the Bulletin Board Service. The software for the system consists of several modules. Their functions provide the capability for system calibration as well as displaying the pressure input to the MPX5100 transducer. Figure 5 is a flowchart for the program that controls the system. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1305 START INITIALIZE DISPLAY I/O PORTS INITIALIZE TIMER REGISTERS ALLOW INTERRUPTS PERFORM AUTO ZERO SLOPE = 64 TIMER INTERRUPT YES J1 OUT? SERVICE TIMER REGISTERS SETUP COUNTER FOR NEXT INTERRUPT SERVICE LIQUID CRYSTAL DISPLAY RETURN FROM INTERRUPT SLOPE = 63 NO J2 OUT? YES SLOPE = 65 Freescale Semiconductor, Inc... NO ACCUMULATE 100 A/D CONVERSIONS COMPUTE INPUT PRESSURE CONVERT TO DECIMAL PLACE IN RESULT OUTPUT BUFFER Figure 5. DEVB-114 Software Flowchart The compiler used in this project was provided by BYTE CRAFT LTD. (519) 888-6911. A compiler listing of the program is included at the end of this document. The following is a brief explanation of the routines: delay() Used to provide approximately a 20 ms loop. read_a2d() Performs one hundred reads on the analog to digital converter on multiplexer channel 5 and returns the accumulation. fixcompare() Services the internal timer for 30 ms timer compare interrupts. TIMERCMP() Alternates the data and backplane for the liquid crystal display. initio() Sets up the microcomputer's I/O ports, timer, allows processor interrupts, and calls adzero(). adzero() This routine is necessary at power-up time because it delays the power supply and allows the Motorola Sensor Device Data transducer to stabilize. It then calls `read_atod()' and saves the returned value as the sensors output voltage with zero pressure applied. cvt_bin_dec(unsigned long arg) This routine converts the unsigned binary argument passed in `arg' to a five digit decimal number in an array called `digit'. It then uses the decimal results for each digit as an index into a table that converts the decimal number into a segment pattern for the display. It is then output to the display. display_psi() This routine is called from `main()'. The analog to digital converter routine is called, the pressure is calculated, and the pressure applied to the sensor is displayed. The loop then repeats. main() This is the main routine called from reset. It calls `initio()' to set up the system's I/O. `display_psi()' is called to compute and display the pressure applied to the sensor. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-223 AN1305 Freescale Semiconductor, Inc. SOFTWARE SOURCE/ASSEMBLY PROGRAM CODE #pragma option v ; /* rev 1.1 code rewritten to use the MC68HC705B5 instead of the MC68HC805B6. WLL 6/17/91 THE FOLLOWING 'C' SOURCE CODE IS WRITTEN FOR THE DEVB-114 DEMONSTRATION BOARD. IT WAS COMPILED WITH A COMPILER COURTESY OF: BYTE CRAFT LTD. 421 KING ST. WATERLOO, ONTARIO CANADA N2J 4E4 (519)888-6911 Freescale Semiconductor, Inc... SOME SOURCE CODE CHANGES MAY BE NECESSARY FOR COMPILATION WITH OTHER COMPILERS. BILL LUCAS 8/5/90 MOTOROLA, SPS */ 0800 1700 0050 0096 #pragma memory ROMPROG [5888] #pragma memory RAMPAGE0 [150] 1FFE 1FFC 1FFA 1FF8 1FF6 1FF4 1FF2 /* #pragma #pragma #pragma #pragma #pragma #pragma #pragma @ 0x0800 ; @ 0x0050 ; Vector assignments */ vector __RESET @ 0x1ffe vector __SWI @ 0x1ffc vector IRQ @ 0x1ffa vector TIMERCAP @ 0x1ff8 vector TIMERCMP @ 0x1ff6 vector TIMEROV @ 0x1ff4 vector SCI @ 0x1ff2 ; ; ; ; ; ; ; #pragma has STOP ; #pragma has WAIT ; #pragma has MUL ; 0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 3-224 /* #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma Register assignments for the 68HC705B5 microcontroller */ portrw porta @ 0x00; /* portrw portb @ 0x01; /* portrw portc @ 0x02; /* portrw portd @ 0x03; /* in ,- ,SS ,SCK ,MOSI,MISO,TxD,RxD portrw ddra @ 0x04; /* Data direction, Port A portrw ddrb @ 0x05; /* Data direction, Port B portrw ddrc @ 0x06; /* Data direction, Port C (all output) portrw eeclk @ 0x07; /* eeprom/eclk cntl */ portrw addata @ 0x08; /* a/d data register */ portrw adstat @ 0x09; /* a/d stat/control */ portrw plma @ 0x0a; /* pulse length modulation a */ portrw plmb @ 0x0b; /* pulse length modulation b */ portrw misc @ 0x0c; /* miscellaneous register */ portrw scibaud @ 0x0d; /* sci baud rate register */ portrw scicntl1 @ 0x0e; /* sci control 1 */ portrw scicntl2 @ 0x0f; /* sci control 2 */ portrw scistat @ 0x10; /* sci status reg */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com */ */ */ */ */ */ */ Motorola Sensor Device Data Freescale Semiconductor, Inc. 0011 0012 0013 0014 0015 0016 0017 0018 0019 001A 001B 001C 001D 001E 001F #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw portrw scidata tcr tsr icaphi1 icaplo1 ocmphi1 ocmplo1 tcnthi tcntlo acnthi acntlo icaphi2 icaplo2 ocmphi2 ocmplo2 @ @ @ @ @ @ @ @ @ @ @ @ @ @ @ 0x11; 0x12; 0x13; 0x14; 0x15; 0x16; 0x17; 0x18; 0x19; 0x1A; 0x1B; 0x1c; 0x1d; 0x1e; 0x1f; /* /* /* /* /* /* /* /* /* /* /* /* /* /* /* AN1305 SCI Data */ ICIE,OCIE,TOIE,0;0,0,IEGE,OLVL */ ICF,OCF,TOF,0; 0,0,0,0 */ Input Capture Reg (Hi-0x14, Lo-0x15) */ Input Capture Reg (Hi-0x14, Lo-0x15) */ Output Compare Reg (Hi-0x16, Lo-0x17)*/ Output Compare Reg (Hi-0x16, Lo-0x17)*/ Timer Count Reg (Hi-0x18, Lo-0x19) */ Timer Count Reg (Hi-0x18, Lo-0x19) */ Alternate Count Reg (Hi-$1A, Lo-$1B) */ Alternate Count Reg (Hi-$1A, Lo-$1B) */ Input Capture Reg (Hi-0x1c, Lo-0x1d) */ Input Capture Reg (Hi-0x1c, Lo-0x1d) */ Output Compare Reg (Hi-0x1e, Lo-0x1f)*/ Output Compare Reg (Hi-0x1e, Lo-0x1f)*/ /* put constants and variables here...they must be global */ Freescale Semiconductor, Inc... 1EFE 74 /***********************************************************************/ #pragma mor @ 0x1EFE = 0x74; /* this disables the watchdog counter and does not add pull-down resistors on ports B and C */ 0800 FC 30 DA 7A 36 6E E6 38 FE 0809 3E const char lcdtab[]={0xfc,0x30,0xda,0x7a,0x36,0x6e,0xe6,0x38,0xfe,0x3e }; 080A 27 10 03 E8 00 64 00 0A /* lcd pattern table 0 1 2 3 4 5 const long dectable[] = { 10000, 1000, 100, 10 }; 6 7 8 9 */ 0050 0005 unsigned int digit[5]; /* buffer to hold results from cvt_bin_dec functio */ 0000 registera ac; /* processor's A register */ 0055 long atodtemp; /* temp to accumulate 100 a/d readings for smoothing */ 0059 long slope; /* multiplier for adc to engineering units conversion */ 005B int adcnt; /* a/d converter loop counter */ 005C long xdcr_offset; /* initial xdcr offset */ 005E 0060 unsigned long i,j; /* counter for loops */ 0062 int k; /* misc variable */ struct bothbytes { int hi; int lo; }; union isboth { long l; struct bothbytes b; }; 0063 0002 Motorola Sensor Device Data union isboth q; /* used for timer set-up */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-225 Freescale Semiconductor, Inc. AN1305 /**************************************************************************/ /* code starts here */ /**************************************************************************/ /* these interrupts are not used...give them a graceful return if for some reason one occurs */ 1FFC 0812 1FFA 0813 1FF8 0814 1FF4 0815 1FF2 0816 08 80 08 80 08 80 08 80 08 80 12 __SWI(){} RTI 13 IRQ(){} RTI 14 TIMERCAP(){} RTI 15 TIMEROV(){} RTI 16 SCI(){} RTI Freescale Semiconductor, Inc... /**************************************************************************/ 0817 0818 081A 081C 081E 0820 0822 0824 0826 0828 082A 082C 082E 0830 0832 0834 0836 4F 3F B7 B6 B7 B6 B7 B6 A0 B6 A2 24 3C 26 3C 20 81 57 58 57 5E 58 5F 5F 20 5E 4E 08 5F 02 5E EE CLRA CLR STA LDA STA LDA STA LDA SUB LDA SBC BCC INC BNE INC BRA RTS void delay(void) /* just hang around for a while */ { for (i=0; i<20000; ++i); $57 $58 $57 $5E $58 $5F $5F #$20 $5E #$4E $0836 $5F $0834 $5E $0824 } /**************************************************************************/ read_a2d(void) { /* read the a/d converter on channel 5 and accumulate the result in atodtemp */ 0837 0839 083B 083C 083E 0840 0842 0844 3F 3F 4F B7 B6 A8 A1 24 3-226 56 55 5B 5B 80 E4 21 CLR CLR CLRA STA LDA EOR CMP BCC $56 $55 atodtemp=0; /* zero for accumulation */ for ( adcnt = 0 ; adcnt<100; ++adcnt) /* do 100 a/d conversions */ $5B $5B #$80 #$E4 $0867 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1305 { 0846 0848 084A 084D 084F 0851 0853 0855 0857 0859 085B 085D 085F 0861 A6 B7 0F B6 3F B7 BB B7 B6 B9 B7 B7 B6 B7 25 09 09 FD 08 57 58 56 58 57 55 57 55 58 56 LDA #$25 STA $09 BRCLR 7,$09,$084A LDA $08 CLR $57 STA $58 ADD $56 STA $58 LDA $57 ADC $55 STA $57 STA $55 LDA $58 STA $56 0863 0865 0867 0869 086B 086D 086F 0871 0873 0875 0878 087B 087D 087F 3C 20 B6 B7 B6 B7 3F A6 B7 CD CD BF B7 81 5B D7 56 58 55 57 66 64 67 0A 5E 0A 8F 55 56 INC BRA LDA STA LDA STA CLR LDA STA JSR JSR STX STA RTS adstat = 0x25; /* convert on channel 5 */ while (!(adstat & 0x80)); /* wait for a/d to complete */ atodtemp = addata + atodtemp; Freescale Semiconductor, Inc... } $5B $083E $56 $58 $55 $57 $66 #$64 $67 $0A5E $0A8F $55 $56 atodtemp = atodtemp/100; return atodtemp; } /**************************************************************************/ 0880 0882 0884 0886 0888 088A 088C 088E 0890 0892 0894 0896 0898 089A B6 B7 B6 B7 AB B7 B6 A9 B7 B7 B6 B6 B7 81 18 63 19 64 4C 64 63 1D 63 16 13 64 17 LDA STA LDA STA ADD STA LDA ADC STA STA LDA LDA STA RTS $18 $63 $19 $64 #$4C $64 $63 #$1D $63 $16 $13 $64 $17 1FF6 08 9B Motorola Sensor Device Data void fixcompare (void) /* sets-up the timer compare for the next interrup */ { q.b.hi =tcnthi; q.b.lo = tcntlo; q.l +=7500; /* ((4mhz xtal/2)/4) = counter period = 2us.*7500 = 15ms.*/ ocmphi1 = q.b.hi; ac=tsr; ocmplo1 = q.b.lo; } /*************************************************************************/ void TIMERCMP (void) /* timer service module */ { www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-227 Freescale Semiconductor, Inc. AN1305 089B 089D 089F 08A1 08A3 33 33 33 AD 80 02 01 00 DD COM COM COM BSR RTI $02 $01 $00 $0880 portc =~ portc; portb =~ portb; porta =~ porta; fixcompare(); /* service the lcd */ } /************************************************************************/ void adzero(void) /* called by initio() to save initial xdcr's zero pressure offset voltage output */ Freescale Semiconductor, Inc... { 08A4 08A5 08A7 08A9 08AB 08AD 08AF 08B1 08B3 08B5 08B7 08B9 4F 3F B7 B6 B7 B6 B7 B6 A0 B6 A2 24 57 58 57 60 58 61 61 14 60 00 0B CLRA CLR STA LDA STA LDA STA LDA SUB LDA SBC BCC for ( j=0; j<20; ++j) /* give the sensor time to "warm-up" and the $57 $58 $57 $60 $58 $61 $61 #$14 $60 #$00 $08C6 power supply time to settle down */ { 08BB CD 08 17 JSR $0817 delay(); } 08BE 08C0 08C2 08C4 08C6 08C9 08CB 08CD 3C 26 3C 20 CD 3F B7 81 61 02 60 EB 08 37 5C 5D INC BNE INC BRA JSR CLR STA RTS $61 $08C4 $60 $08B1 $0837 $5C $5D xdcr_offset = read_a2d(); } /**************************************************************************/ 08CE 08D0 08D2 08D4 08D6 08D8 08DA 08DC 08DE 08E0 08E2 08E4 08E6 08E8 A6 B7 3F 3F 3F A6 B7 B7 B7 B6 3F 3F B6 AD 3-228 20 09 02 01 00 FF 06 05 04 13 1E 16 1F 96 LDA STA CLR CLR CLR LDA STA STA STA LDA CLR CLR LDA BSR #$20 $09 $02 $01 $00 #$FF $06 $05 $04 $13 $1E $16 $1F $0880 void initio (void) /* setup the I/O */ { adstat = 0x20; /* power-up the A/D */ porta = portb = portc = 0; ddra = ddrb = ddrc = 0xff; ac=tsr; /* dummy read */ ocmphi1 = ocmphi2 = 0; ac = ocmplo2; /* clear out output compare 2 if it happens to be set */ fixcompare(); /* set-up for the first timer interrupt */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 08EA A6 40 08EC B7 12 08EE 9A LDA STA CLI #$40 $12 08EF 08F1 08F3 08F5 08F7 08F9 08FB 08FD LDA STA LDA STA LDA STA BSR RTS #$CC $02 #$BE $01 #$C4 $00 $08A4 A6 B7 A6 B7 A6 B7 AD 81 CC 02 BE 01 C4 00 A7 AN1305 tcr = 0x40; CLI; /* let the interrupts begin ! /* write CAL to the display */ portc = 0xcc; /* C */ */ portb = 0xbe; /* A */ porta = 0xc4; /* L */ adzero(); } /**************************************************************************/ void cvt_bin_dec(unsigned long arg) Freescale Semiconductor, Inc... /* First converts the argument to a five digit decimal value. The msd is in the lowest address. Then leading zero suppresses the value and writes it to the display ports. The argument value range is 0..65535 decimal. */ 0069 08FE 0900 006B 006C 0902 0903 0905 0907 0909 { BF 69 B7 6A 4F B7 B6 A1 24 6B 6B 05 07 STX STA CLRA STA LDA CMP BCC $69 $6A char i; unsigned long l; for ( i=0; i < 5; ++i ) $6B $6B #$05 $0912 { 090B 97 090C 6F 50 TAX CLR 090E 0910 0912 0913 0915 0917 0919 3C 20 4F B7 B6 A1 24 6B 6B 04 70 INC BRA CLRA STA LDA CMP BCC 091B 091C 091D 0920 0922 0924 0927 0929 97 58 D6 B1 26 D6 B1 27 08 0B 6A 07 08 0A 69 5C TAX LSLX LDA CMP BNE LDA CMP BEQ 092B BE 6B 092D 58 092E D6 08 0A LDX LSLX LDA digit[i] = 0x0; /* put blanks in all digit positions */ $50,X } 6B F3 $6B $0905 for ( i=0; i < 4; ++i ) $6B $6B #$04 $098B { if ( arg >= dectable [i] ) $080B,X $6A $092B $080A,X $69 $0987 { $6B l = dectable[i]; $080A,X Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-229 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1305 0931 0933 0936 0938 093A 093C 093E 0940 0942 0944 0946 0948 094B 094E 0950 0952 0954 0956 0958 095A 095C 095E 0960 0962 0964 0966 0969 096B 096D 096F 0971 0973 0975 0977 0979 097B 097D 097F 0981 0983 0985 B7 D6 B7 B6 B7 B6 B7 B6 B7 B6 B7 CD CD BF B7 BE E7 BE E6 3F B7 B6 B7 B6 B7 CD BF B7 33 30 26 3C B6 BB B7 B6 B9 B7 B7 B6 B7 6C 08 6D 6A 58 69 57 6C 66 6D 67 0A 0A 57 58 6B 50 6B 50 57 58 6C 66 6D 67 0A 57 58 57 58 02 57 58 6A 58 57 69 57 69 58 6A 0B 5E 8F 3F STA LDA STA LDA STA LDA STA LDA STA LDA STA JSR JSR STX STA LDX STA LDX LDA CLR STA LDA STA LDA STA JSR STX STA COM NEG BNE INC LDA ADD STA LDA ADC STA STA LDA STA $6C $080B,X $6D $6A $58 $69 $57 $6C $66 $6D $67 $0A5E $0A8F $57 $58 $6B $50,X $6B $50,X $57 $58 $6C $66 $6D $67 $0A3F $57 $58 $57 $58 $0975 $57 $58 $6A $58 $57 $69 $57 $69 $58 $6A digit[i] = arg / l; arg = arg-(digit[i] * l); } } 0987 0989 098B 098D 098F 0991 0993 0995 0997 3C 20 B6 B7 B6 B7 BE B6 E7 0999 9B 3-230 6B 8A 6A 58 69 57 6B 58 50 INC BRA LDA STA LDA STA LDX LDA STA SEI $6B $0915 $6A $58 $69 $57 $6B $58 $50,X digit[i] = arg; /* now zero suppress and send the lcd pattern to the display */ SEI; www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 099A 099C 099E 09A0 09A2 09A4 09A7 09A9 09AB 09AD 09AF 09B1 09B3 09B5 09B7 09BA 09BC 09BE 09C1 09C2 09C4 09C5 09C8 3D 26 3F 20 BE D6 B7 3D 26 3D 26 3F 20 BE D6 B7 BE D6 4C B7 9A CD 81 50 04 02 07 50 08 00 02 50 08 51 04 01 07 51 08 00 01 52 08 00 00 08 17 TST BNE CLR BRA LDX LDA STA TST BNE TST BNE CLR BRA LDX LDA STA LDX LDA INCA STA CLI JSR RTS $50 $09A2 $02 $09A9 $50 $0800,X $02 $50 $09B5 $51 $09B5 $01 $09BC $51 $0800,X $01 $52 $0800,X if ( digit[0] == 0 ) AN1305 /* leading zero suppression */ portc = 0; else portc = ( lcdtab[digit[0]] ); /* 100's digit */ if ( digit[0] == 0 && digit[1] == 0 ) portb=0; else portb = ( lcdtab[digit[1]] ); /* 10's digit */ porta = ( lcdtab[digit[2]]+1 ); /* 1's digit + decimal point */ $00 CLI; $0817 delay(); } /****************************************************************/ 09C9 09CB 09CD 09CF 09D1 09D3 3F A6 B7 B6 A4 B7 59 40 5A 03 C0 62 CLR LDA STA LDA AND STA $59 #$40 $5A $03 #$C0 $62 09D5 09D7 09D9 09DB 09DD 09DF A1 26 3F A6 B7 B6 80 06 59 41 5A 62 CMP BNE CLR LDA STA LDA #$80 $09DF $59 #$41 $5A $62 Motorola Sensor Device Data void display_psi(void) /* At power-up it is assumed that the pressure port of the sensor is open to atmosphere. The code in initio() delays for the sensor and power to stabilize. One hundred A/D conversions are averaged and divided by 100. The result is called xdcr_offset. This routine calls the A/D routine which performs one hundred conversions, divides the result by 100 and returns the value. If the value returned is less than or equal to the xdcr_offset, the value of xdcr_offset is substituted. If the value returned is greater than xdcr_offset, xdcr_offset is subtracted from the returned value. That result is multiplied by a constant to yield pressure in PSI * 10 to yield a "decimal point". */ { while(1) { slope = 64; k = portd & 0xc0; if ( k == 0x80 ) /* this lets us "rubber" the slope to closer fit the slope of the sensor */ /* J2 removed, J1 installed */ slope = 65; if ( k == 0x40 ) /* J1 removed, J2 installed */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-231 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1305 09E1 09E3 09E5 09E7 09E9 A1 26 3F A6 B7 40 06 59 3F 5A CMP BNE CLR LDA STA #$40 $09EB $59 #$3F $5A 09EB 09EE 09F0 09F2 09F4 09F6 09F8 09FA 09FC 09FE 0A00 0A02 0A04 0A06 0A08 0A0A 0A0C 0A0E 0A10 0A12 0A14 0A16 0A18 0A1A 0A1C 0A1E 0A20 0A22 0A24 0A26 0A28 0A2A 0A2D 0A2F 0A31 0A34 0A36 CD 3F B7 B0 B7 B6 A8 B7 B6 A8 B2 BA 22 B6 B7 B6 B7 B6 B0 B7 B6 B2 B7 B6 B7 B6 B7 B6 B7 B6 B7 CD BF B7 CD 20 81 08 37 55 56 5D 58 5C 80 57 55 80 57 58 08 5C 55 5D 56 56 5D 56 55 5C 55 56 58 55 57 59 66 5A 67 0A 3F 55 56 08 FE 93 JSR CLR STA SUB STA LDA EOR STA LDA EOR SBC ORA BHI LDA STA LDA STA LDA SUB STA LDA SBC STA LDA STA LDA STA LDA STA LDA STA JSR STX STA JSR BRA RTS $0837 $55 $56 $5D $58 $5C #$80 $57 $55 #$80 $57 $58 $0A0E $5C $55 $5D $56 $56 $5D $56 $55 $5C $55 $56 $58 $55 $57 $59 $66 $5A $67 $0A3F $55 $56 $08FE $09C9 slope = 63; /* else both jumpers are removed or installed... don't change the slope */ atodtemp = read_a2d(); /* atodtemp = raw a/d ( 0..255 ) */ if ( atodtemp <= xdcr_offset ) atodtemp = xdcr_offset; atodtemp -= xdcr_offset; /* remove the offset */ atodtemp *= slope; /* convert to psi */ cvt_bin_dec( atodtemp ); /* convert to decimal and display */ } } /************************************************************************/ 0A37 0A3A 0A3C 0A3E CD 08 CE AD 8D 20 FE 81 0A3F BE 58 0A41 B6 67 3-232 JSR BSR BRA RTS $08CE $09C9 $0A3C LDX LDA $58 $67 main() { initio(); /* set-up the processor's i/o */ display_psi(); while(1); /* should never get here */ } www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 0A43 0A44 0A46 0A48 0A4A 0A4C 0A4D 0A4F 0A51 0A53 0A55 0A56 0A58 0A5A 0A5B 0A5D 42 B7 BF BE B6 42 BB B7 BE B6 42 BB B7 97 B6 81 0A5E 0A60 0A61 0A63 0A65 0A66 0A68 0A6A 0A6C 0A6E 0A70 0A72 0A74 0A76 0A78 0A7A 0A7C 0A7E 0A80 0A82 0A84 0A86 0A88 0A89 0A8A 0A8C 0A8E 0A8F 0A90 0A91 0A93 0A94 1FFE 3F 5F 3F 3F 5C 38 39 39 39 B6 B0 B7 B6 B2 B7 24 B6 BB B7 B6 B9 B7 99 59 39 24 81 53 9F BE 53 81 0A 70 71 57 67 71 71 58 66 71 71 70 70 6E 6F 58 57 6E 6F 6E 67 6E 6F 66 6F 0D 67 6E 6E 66 6F 6F 70 D8 70 MUL STA STX LDX LDA MUL ADD STA LDX LDA MUL ADD STA TAX LDA RTS CLR CLRX CLR CLR INCX LSL ROL ROL ROL LDA SUB STA LDA SBC STA BCC LDA ADD STA LDA ADC STA SEC ROLX ROL BCC RTS COMX TXA LDX COMX RTS AN1305 $70 $71 $57 $67 $71 $71 $58 $66 $71 $71 $70 $70 $6E $6F $58 $57 $6E $6F $6E $67 $6E $6F $66 $6F $0A89 $67 $6E $6E $66 $6F $6F $70 $0A66 $70 37 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-233 Freescale Semiconductor, Inc. AN1305 Freescale Semiconductor, Inc... SYMBOL TABLE LABEL VALUE LABEL VALUE LABEL VALUE LABEL VALUE IRQ TIMEROV __MUL16x16 __STOP acnthi adstat b ddrb digit hi icaplo1 j lo ocmphi2 plmb portd scicntl1 slope tsr 0813 0815 0A3F 0000 001A 0009 0000 0005 0050 0000 0015 0060 0001 001E 000B 0003 000E 0059 0013 SCI __LDIV __RDIV __SWI acntlo adzero bothbytes ddrc display_psi i icaplo2 k main ocmplo1 porta q scicntl2 tcnthi xdcr_offset 0816 0A5E 0A8F 0812 001B 08A4 0002 0006 09C9 005E 001D 0062 0A37 0017 0000 0063 000F 0018 005C TIMERCAP __LongIX __RESET __WAIT adcnt arg cvt_bin_dec dectable eeclk icaphi1 initio l misc ocmplo2 portb read_a2d scidata tcntlo 0814 0066 1FFE 0000 005B 0069 08FE 080A 0007 0014 08CE 0000 000C 001F 0001 0837 0011 0019 TIMERCMP __MUL __STARTUP __longAC addata atodtemp ddra delay fixcompare icaphi2 isboth lcdtab ocmphi1 plma portc scibaud scistat tcr 089B 0000 0000 0057 0008 0055 0004 0817 0880 001C 0002 0800 0016 000A 0002 000D 0010 0012 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MEMORY USAGE MAP ('X' = Used, '-' = Unused) 0100 0140 0180 01C0 : : : : ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- --------------X- 0800 0840 0880 08C0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0900 0940 0980 09C0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0A00 0A40 0A80 0AC0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX ---------------- XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXX----------- ---------------- XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX ---------------- ---------------- XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX ---------------- ---------------- 1F00 1F40 1F80 1FC0 : : : : ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- --XXXXXXXXXXXXXX All other memory blocks unused. Errors : 0 Warnings : 0 3-234 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Compensated Sensor Bar Graph Pressure Gauge AN1309 Prepared by: Warren Schultz Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Compensated semiconductor pressure sensors such as the MPX2000 family are relatively easy to interface with digital systems. With these sensors and the circuitry described herein, pressure is translated into a 0.5 to 4.5 volt output range that is directly compatible with Microcomputer A/D inputs. The 0.5 to 4.5 volt range also facilitates interface with an LM3914, making Bar Graph Pressure Gauges relatively simple. Figure 1. DEVB147 Compensated Pressure Sensor Evaluation Board (Board No Longer Available) REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-235 Freescale Semiconductor, Inc. AN1309 PIN-BY-PIN DESCRIPTION EVALUATION BOARD DESCRIPTION Freescale Semiconductor, Inc... The information required to use evaluation board number DEVB147 follows, and a discussion of the design appears in the Design Considerations section. FUNCTION The evaluation board shown in Figure 1 is supplied with an MPX2100DP sensor and provides a 100 kPa full scale pressure measurement. It has two input ports. P1, the pressure port, is on the top side of the sensor and P2, a vacuum port, is on the bottom side. These ports can be supplied up to 100 kPa (15 psi) of pressure on P1 or up to 100 kPa of vacuum on P2, or a differential pressure up to 100 kPa between P1 and P2. Any of these sources will produce the same output. The primary output is a 10 segment LED bar graph, which is labeled in increments of 10% of full scale, or 10 kPa with the MPX2100 sensor. An analog output is also provided. It nominally supplies 0.5 volts at zero pressure and 4.5 volts at full scale. Zero and full scale adjustments are made with potentiometers so labeled at the bottom of the board. Both adjustments are independent of one another. ELECTRICAL CHARACTERISTICS The following electrical characteristics are included as a guide to operation. Characteristic Symbol Min Typ Max Units Power Supply Voltage B+ 6.8 -- 13.2 dc Volts PFS -- -- 100 kPa PMAX -- -- 700 kPa VFS -- 4.5 -- Volts VOFF -- 0.5 -- Volts Analog Sensitivity SAOUT -- 40 -- mV/kPa Quiescent Current ICC -- 40 -- mA Full Scale Current IFS -- 160 -- mA Full Scale Pressure Overpressure Analog Full Scale Analog Zero Pressure Offset CONTENT Board contents are described in the parts list shown in Table 1. A schematic and silk screen plot are shown in Figures 2 and 6. A pin by pin circuit description follows. 3-236 B+: Input power is supplied at the B+ terminal. Minimum input voltage is 6.8 volts and maximum is 13.2 volts. The upper limit is based upon power dissipation in the LM3914 assuming all 10 LED's are lit and ambient temperature is 25C. The board will survive input transients up to 25 volts provided that average power dissipation in the LM3914 does not exceed 1.3 watts. OUT: An analog output is supplied at the OUT terminal. The signal it provides is nominally 0.5 volts at zero pressure and 4.5 volts at full scale. Zero pressure voltage is adjustable and set with R11. This output is designed to be directly connected to a microcomputer A/D channel, such as one of the E ports on an MC68HC11. GND: There are two ground connections. The ground terminal on the left side of the board is intended for use as the power supply return. On the right side of the board one of the test point terminals is also connected to ground. It provides a convenient place to connect instrumentation grounds. TP1: Test point 1 is connected to the LM3914's full scale reference voltage which sets the trip point for the uppermost LED segment. This voltage is adjusted via R1 to set full scale pressure. TP2: Test point 2 is connected to the +5.0 volt regulator output. It can be used to verify that supply voltage is within its 4.75 to 5.25 volt tolerance. P1, P2: Pressure and Vacuum ports P1 and P2 protrude from the sensor on the right side of the board. Pressure port P1 is on the top and vacuum port P2 is on the bottom. Neither port is labeled. Maximum safe pressure is 700 kPa. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1309 S1 B+ ON/OFF D1 U3A 4 3 + 1 2 - MC33274 C2 0.1 F MC78L05ACP R7 75 O G 1 Freescale Semiconductor, Inc... 2 3 2 R8 75 4 1 R5 1k R13 1k R10 820 ZERO CAL. R11 200 1 2 3 4 5 6 7 8 9 7.5 k 13 U3D - 14 12 + MC33274 R3 1.2 k XDCR1 MPX2100DP GND D6 D7 D8 D1-D10 MV57164 BAR GRAPH R6 U1 3 I D9 D10 D2 D3 D4 D5 C1 1 F 5 U3B + 7 6 - MC33274 R4 R1 1k FULL SCALE CAL. U2 18 LED LED 17 GND LED 16 B+ LED RLO LED 15 14 SIG LED 13 RHI LED 12 REF LED 11 ADJ LED MOD LED 10 LM3914N TP1 (FULL SCALE VOLTAGE) GND R2 2.7 k TP2 +5 VOLTS R14 470 1k U3C 10 MC33274 + 9 - 11 8 D11 MV57124A POWER ON INDICATOR R12 470 R9 1k ANALOG OUT Figure 2. Compensated Pressure Sensor EVB Schematic B+ C1 0.1 F 3 U1 I MC78L05ACP O 1 G C2 1 F XDCR MPX2100 3 2 2 U2B 5 4 7 + 6 - MC33274 R3 4 1 R4 1 k GND R5 1 k 13 12 100 k U2D - 14 + MC33274 U2C MC33274 10 + 9 - NOTE: For zero pressure voltage independent of sensor common mode R6/R7 = R2/R1 R7 R6 1k 1k 8 3 U2A 1 + 2 - MC33274 R2 R1 1k 1k OUTPUT 11 VOFFSET Figure 3. Compensated Sensor Interface Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-237 AN1309 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... DESIGN CONSIDERATIONS In this type of application the design challenge is how to take a relatively small DC coupled differential signal and produce a ground referenced output that is suitable for driving microcomputer A/D inputs. A user friendly interface circuit that will do this job is shown in Figure 3. It uses one quad op amp and several resistors to amplify and level shift the sensor's output. Most of the amplification is done in U2D which is configured as a differential amplifier. It is isolated from the sensor's positive output by U2B. The purpose of U2B is to prevent feedback current that flows through R3 and R4 from flowing into the sensor. At zero pressure the voltage from pin 2 to pin 4 on the sensor is zero volts. For example with the common mode voltage at 2.5 volts, the zero pressure output voltage at pin 14 of U2D is then 2.5 volts, since any other voltage would be coupled back to pin 13 via R3 and create a nonzero bias across U2D's differential inputs. This 2.5 volt zero pressure DC output voltage is then level translated to the desired zero pressure offset voltage (VOFFSET) by U2C and U2A. To see how the level translation works, assume 0.5 volts at (VOFFSET). With 2.5 volts at pin 10, pin 9 is also at 2.5 volts. This leaves 2.5 - 0.5 = 2.0 volts across R7. Since no current flows into pin 9, the same current flows through R6, producing 2.0 volts across R6 also. Adding the voltages (0.5 + 2.0 + 2.0) yields 4.5 volts at pin 8. Similarly 2.5 volts at pin 3 implies 2.5 volts at pin 2, and the drop across R2 is 4.5 V - 2.5 V = 2.0 volts. Again 2.0 volts across R2 implies an equal drop across R1, and the voltage at pin 1 is 2.5 V - 2.0 V = 0.5 volts. For this DC output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that R6/R7 = R2/R1. Gain is close but not exactly equal to R3/R4(R1/R2+1), which predicts 200.0 for the values shown in Figure 3. A more exact calculation can be performed by doing a nodal analysis, which yields 199.9. Cascading the gains of U2D and U2A using standard op amp gain equations does not give an exact result, because the sensor's negative going differential signal at pin 4 subtracts from the DC level that is amplified by U2A. The resulting 0.5 V to 4.5 V output from U2A is directly compatible with microprocessor A/D inputs. Tying this output to an LM3914 for a bar graph readout is also very straight forward. The block diagram that appears in Figure 4 shows the LM3914's internal architecture. Since the lower resistor in the input comparator chain is pinned out at RLO, it is a simple matter to tie this pin to a voltage that is approximately equal to the interface circuit's 0.5 volt zero pressure output voltage. In Figure 2, this is accomplished by dividing down the 5.0 volt regulator's output voltage through R13 and adjustment pot R11. The voltage generated at R11's wiper is the offset voltage identified as VOFFSET in Figure 3. Its source impedance is chosen to keep the total input impedance to U3C at approximately 1K. The wiper of R11 is also fed into RLO for zeroing the bar graph. The full scale measurement is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. An internal regulator on the LM3914 sets this voltage with the aid of resistors R2, R3, and adjustment pot R1 that are shown in Figure 2. Five volt regulated power is supplied by an MC78L05. The LED's are powered directly from LM3914 outputs, which are set up as current sources. Output current to each LED is approximately 10 times the reference current that flows from pin 7 through R3, R1, and R2 to ground. In this design it is nominally (4.5 V/4.9K)10 = 9.2 mA. Over a zero to 50C temperature range combined accuracy for the sensor, interface and driver IC are +/- 10%. Given a 10 segment display total accuracy for the bar graph readout is approximately +/- (10 kPa +10%). APPLICATION Using the analog output to provide pressure information to a microcomputer is very straightforward. The output voltage range, which goes from 0.5 volts at zero pressure to 4.5 volts at full scale, is designed to make optimum use of microcomputer A/D inputs. A direct connection from the evaluation board analog output to an A/D input is all that is required. Using the MC68HC11 as an example, the output is connected to any of the E ports, such as port E0 as shown in Figure 5. To get maximum accuracy from the A/D conversion, VREFH is tied to 4.85 volts and VREFL is tied to 0.3 volts by dividing down a 5.0 volt reference with 1% resistors. CONCLUSION Perhaps the most noteworthy aspect to the bar graph pressure gauge described here is the ease with which it can be designed. The interface between an MPX2000 series sensor and LM3914 bar graph display driver consists of one 3-238 quad op amp and a few resistors. The result is a simple and inexpensive circuit that is capable of measuring pressure, vacuum, or differential pressure with an output that is directly compatible to a microprocessor. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. LED V+ LM3914 - + Freescale Semiconductor, Inc... RHI 6 REF OUT 7 + THIS LOAD DETERMINES LED BRIGHTNESS REF ADJ V+ REFERENCE VOLTAGE SOURCE 1.25 V - 8 3 - + 11 1k - + 12 1k - + 13 1k - + 14 - + 15 - + 16 1k - + 17 1k - + 18 1k - + 1 1k 1k RLO COMPARATOR 1 of 10 10 1k 1k V+ FROM PIN 11 4 MODE SELECT AMPLIFIER 9 - BUFFER SIG IN AN1309 5 CONTROLS TYPE OF DISPLAY, BAR OR SINGLE LED 2 V- 20 k + Figure 4. LM3914 Block Diagram Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-239 Freescale Semiconductor, Inc. AN1309 +5 V 15 OHMS 1% 4.85 V VREFH 453 OHMS 1% +12 V VREFL 0.302 V 30.1 OHMS 1% B+ COMPENSATED SENSOR BAR GRAPH PRESSURE GAUGE ANALOG OUT Freescale Semiconductor, Inc... GND MC68HC11 PRESSURE/ VACUUM IN 0 1 2 3 4 5 6 7 PORT E Figure 5. Application Example COMPENSATED PRESSURE SENSOR EVB % FULL SCALE 100 U1 C1 90 U3 80 C2 U3 50 MV57164 60 LM3914N 70 SENSOR 40 30 20 U2 10 R12 R2 R3 R10 R9 R4 R5 R8 R6 R7 TP2 R7 R6 R8 R5 R4 R9 R3 R2 R10 OUT R12 B+ TP1 GND R14 R13 GND DEVB147 R14 ON + R13 POWER R11 R1 ZERO FULL SCALE OFF MOTOROLA DISCRETE APPLICATIONS Figure 6. Silk Screen 3-240 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1309 Table 1. Parts List Freescale Semiconductor, Inc... Designator Qty. Description C1 C2 1 1 Ceramic Capacitor Ceramic Capacitor D1-D10 D11 1 1 Bar Graph LED LED R2 R3 R4, R5, R9, R13 R6 R7, R8 R10 R12, R14 R1 R11 1 1 4 1 2 1 2 1 1 1/4 Watt Film Resistor 1/4 Watt Film Resistor 1/4 Watt Film Resistor 1/4 Watt Film Resistor 1/4 Watt Film Resistor 1/4 Watt Film Resistor 1/4 Watt Film Resistor Trimpot Trimpot S1 1 U1 U2 U3 Value Vendor Part 1.0 F 0.1 F GI GI MV57164 MV57124A Bourns Bourns 3386P-1-102 3386P-1-201 Switch NKK 12SDP2 1 1 1 5.0 V Regulator Bar Graph IC Op Amp Motorola National Motorola MC78L05ACP LM3914N MC33274P XDCR1 1 Pressure Sensor Motorola MPX2100DP -- -- -- -- 1 1 1 1 Terminal Block Test Point Terminal (Black) Test Point Terminal (Red) Test Point Terminal (Yellow) Augat Components Corp. Components Corp. Components Corp. 2SV03 TP1040100 TP1040102 TP1040104 Motorola Sensor Device Data 2.7K 1.2K 1.0K 7.5K 75 820 470 1.0K 200 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-241 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1315 An Evaluation System Interfacing the MPX2000 Series Pressure Sensors to a Microprocessor Prepared by: Bill Lucas Discrete Applications Engineering be used to evaluate any of the MPX2000 series pressure sensors for your specific application. Freescale Semiconductor, Inc... INTRODUCTION Outputs from compensated and calibrated semiconductor pressure sensors such as the MPX2000 series devices are easily amplified and interfaced to a microprocessor. Design considerations and the description of an evaluation board using a simple analog interface connected to a microprocessor is presented here. PURPOSE The evaluation system shown in Figure 1 shows the ease of operating and interfacing the MOTOROLA MPX2000 series pressure sensors to a quad operational amplifier, which amplifies the sensor's output to an acceptable level for an analog-to-digital converter. The output of the op amp is connected to the A/D converter of the microprocessor and that analog value is then converted to engineering units and displayed on a liquid crystal display (LCD). This system may DESCRIPTION The DEVB158 evaluation system is constructed on a small printed circuit board. Designed to be powered from a 12 Vdc power supply, the system will display the pressure applied to the MPX2000 series sensor in pounds per square inch (PSI) on the liquid crystal display. Table 1 shows the pressure sensors that may be used with the system and the pressure range associated with that particular sensor as well as the jumper configuration required to support that sensor. These jumpers are installed at assembly time to correspond with the supplied sensor. Should the user chose to evaluate a different sensor other than that supplied with the board, the jumpers must be changed to correspond to Table 1 for the new sensor. The displayed pressure is scaled to the full scale (PSI) range of the installed pressure sensor. No potentiometers are used in the system to adjust its span and offset. This function is performed by software. Figure 1. DEVB158 2000 Series LCD Pressure Gauge EVB (Board No Longer Available) REV 1 3-242 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. The signal conditioned sensor's zero pressure offset voltage with no pressure applied to the sensor is empirically computed each time power is applied to the system and stored in RAM. The sensitivity of the MPX2000 series pressure sensors is quite repeatable from unit to unit. There is a facility for a small adjustment of the slope constant built into the program. It is accomplished via jumpers J4 thru J7, and will be explained in the OPERATION section. Figure 2 shows the printed circuit silkscreen and Figures 3A and 3B show the schematic for the system. Table 1. Sensor Type J8 J3 J2 J1 0 -1.5 0 - 7.5 0 -15.0 0 - 30 IN OUT OUT OUT IN IN IN IN IN IN OUT OUT IN OUT IN OUT Freescale Semiconductor, Inc... MPX2010 MPX2050 MPX2100 MPX2200 Jumpers Input Pressure PSI AN1315 LCD1 U5 RP1 J1 J2 J3 R4 C6 C1 Y1 C8 TP1 C7 R15 R1 C3 R5 R8 D1 C2 D2 U3 C5 R3 R2 R10 R9 R7 R13 C4 R12 U1 U4 R6 R14 J8 XDCR1 MOTOROLA DISCRETE APPLICATIONS ENGINEERING U2 P1 +12 GND 5.2 R11 J4 J5 J6 J7 DEVB158 2.9 Figure 2. Printed Circuit Silkscreen Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-243 Freescale Semiconductor, Inc. AN1315 The analog section of the system can be broken down into two subsections. These sections are the power supply and the amplification section. The power supply section consists of a diode, used to protect the system from input voltage reversal, and two fixed voltage regulators. The 5 volt regulator (U3) is used to power the microprocessor and display. The 8 volt regulator (U4) is used to power the pressure sensor, voltage references and a voltage offset source. The microprocessor section (U5) requires minimal support hardware to function. The MC34064P-5 (U2) provides an under voltage sense function and is used to reset the microprocessor at system power-up. The 4.0 MHz crystal (Y1) provides the external portion of the oscillator function for clocking the microprocessor and providing a stable base for timing functions. Table 2. Parts List Designators Description Rating Manufacturer Part Number C3, C4, C6 3 0.1 F Ceramic Cap. 50 Vdc Sprague 1C105Z5U104M050B C1, C2, C5 3 1 F Ceramic Cap. 50 Vdc muRATA ERIE RPE123Z5U105M050V 2 22 pF Ceramic Cap. 100 Vdc Mepco/Centralab CN15A220K C7, C8 J1 - J3, J8 Freescale Semiconductor, Inc... Quant. 3 OR 4 #22 or #24 AWG Tined Copper As Required J4 - J7 1 Dual Row Straight 4 Pos. Arranged On 0.1 Grid AMP 87227-2 LCD1 1 Liquid Crystal Display IEE LCD5657 P1 1 Power Connector Phoenix Contact MKDS 1/2-3.81 R1 1 6.98K Ohm resistor 1% R2 1 121 Ohm Resistor 1% R3 1 200 Ohm Resistor 1% R4, R11 2 4.7K Ohm Resistor R7 1 340 Ohm Resistor 1% R5, R6 2 2.0K Ohm Resistor 1% R8 1 23.7 Ohm Resistor 1% R9 1 976 Ohm Resistor 1% R10 1 1K Ohm Resistor 1% R12 1 3.32K Ohm Resistor 1% R13 1 4.53K Ohm Resistor 1% R14 1 402 Ohm Resistor 1% R15 1 10 Meg Ohm Resistor RP1 1 47K Ohm x 7 SIP Resistor 2% CTS 770 Series TP1 1 Test Point Components Corp. TP-104-01-02 U1 1 Quad Operational Amplifier Motorola MC33274P U2 1 Under Voltage Detector Motorola MC34064P-5 U3 1 5 Volt Fixed Voltage Regulator Motorola MC78L05ACP U4 1 8 Volt Fixed Voltage Regulator Motorola MC78L08ACP U5 1 Microprocessor Motorola Motorola MC68HC705B5FN or XC68HC705B5FN XDCR 1 Pressure Sensor Motorola MPX2xxxDP Y1 1 Crystal (Low Profile) CTS ATS040SLV No Designator 1 52 Pin PLCC Socket for U5 AMP 821-575-1 No Designator 4 Jumpers For J4 thru J7 Molex 15-29-1025 No Designator 1 Bare Printed Circuit Board No Designator 4 Self Sticking Feet Fastex 5033-01-00-5001 Red 4.0 MHz Note: All resistors are 1/4 W resistors with a tolerance of 5% unless otherwise noted. Note: All capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted. 3-244 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1315 OPERATIONAL CHARACTERISTICS PIN-BY-PIN DESCRIPTION The following operational characteristics are included as a guide to operation. +12: Input power is supplied at the +12 terminal. The minimum operating voltage is 10.75 Vdc and the maximum operating voltage is 16 Vdc. Characteristic Min Max Unit +12 10.75 16 Volts Operating Current ICC 75 mA Full Scale Pressure MPX2010 MPX2050 MPX2100 MPX2200 Pfs 1.5 7.5 15 30 PSI PSI PSI PSI Freescale Semiconductor, Inc... Symbol Power Supply Voltage GND: The ground terminal is the power supply return for the system. TP1: Test point 1 is connected to the final op amp stage. It is the voltage that is applied to the microprocessor's A/D converter. There are two ports on the pressure sensor located at the bottom center of the printed circuit board. The pressure port is on the top left and the vacuum port is on the bottom right of the sensor. +12 V J8 IS INSTALLED FOR THE MPX2010 ONLY 5 + 4 7 6 -U1A +5 V 6.98K +8 R1 2 MC33274 10 + 8 9 -U1C 3 121 R2 200 R3 1N914 4.7K U2 R4 MC34064P-5 PD0 2-A2 GND +5 V 12 + 14 13 -U1D 976 1K R9 R10 7 x 47K J1 R7 23.7 R8 SENSOR TYPE SELECT U3 1 F 78L05 OUT 1 F GROUND C1 J3 +5 V + J2 0.1 C2 C3 J4 U4 D1 +12 IN P1 1N4002 IN 78L08 OUT GROUND GROUND CPU_RESET 2-B4 TP1 340 IN OUT 2K 2 - 1 3 +U1B 11 + R11 +IN D2 R6 2K +8 4.7K R5 J8 1 4 XDCR1 +5 V +5 V 1 F J5 +8 + 0.1 C5 3.32K R12 C4 VRH 2-D4 4.53K SLOPE ADJ. 402 PD2 2-A3 PD3 2-A3 PD4 2-A3 PD5 2-A3 J6 PD6 2-A3 J7 PD7 2-A3 R13 VRL 2-D4 PD1 2-A2 R14 Figure 3a. Schematic Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-245 3-246 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com PD7 1-E4 PD5 1-E4 PD1 1-E3 PD1 1-E3 PD6 1-E4 PD4 1-E3 PD2 1-E3 PD0 1-C2 3 4 5 9 11 12 13 14 0 PD7 PD6 PD5 PD4 PD3 PD2 PD1 47 +5 V 2 36 IRQ* 19 37 PD0 49 28 1 7 18 6 44 15 C6 5 35 VPP6 34 0.1 43 7 PORTC RESET* 42 6 CPU_RESET 1-E2 48 5 VDD 4 10 45 8 31 46 3 32 9 41 VSS 39 0 10 2 29 22 TCAP1 37 11 38 32 26 U5 6 27 33 PORTB 7 12 34 13 23 TCAP2 21 D/A MC68HC705B5 1 30 LCD1 5 4 50 RDI 35 14 3 52 TDO 36 15 24 31 25 0 16 2 VRL 1-C4 7 VRL 29 22 Freescale Semiconductor, Inc... 30 23 1 17 24 7 25 PORTA 18 5 20 27 VRH 1-C4 8 VRH 6 19 4 20 PLMA 26 21 3 OSC1 OSC2 28 1 BLK PLN 16 R15 10M 17 C7 22 pF PINS: 2-4, 33, 38-40 C8 Y1 4.00 MHz 22 pF AN1315 Freescale Semiconductor, Inc. Figure 3b. Schematic Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... OPERATION Connect the system to a 12 Vdc regulated power supply. (Note the polarity marked on the power terminal P1.) Depending on the particular pressure sensor being used with the system, wire jumpers J1 through J3 and J8 must be installed at board assembly time. If at some later time it is desirable to change the type of sensor that is installed on the board, jumpers J1 through J3 and J8, must be reconfigured for the system to function properly (see Table 1). If an invalid J1 through J3 jumper combination (i.e., not listed in Table 1) is used the LCD will display "SE" to indicate that condition. These jumpers are read by the software and are used to determine which sensor is installed on the board. Wire jumper J8 is installed only when an MPX2010DP pressure sensor is used on the system. The purpose of wire jumper J8 will be explained later in the text. Jumpers J4 through J7 are read by the software to allow the user to adjust the slope constant used for the engineering units calculation (see Table 3). The pressure and vacuum ports on the sensor must be left open to atmosphere anytime the board is powered-up. This is because the zero pressure offset voltage is computed at power-up. When you apply power to the system, the LCD will display CAL for approximately 5 seconds. After that time, pressure or vacuum may be applied to the sensor. The system will then start displaying the applied pressure in PSI. Table 3. J7 J6 J5 J4 Action IN IN IN IN IN IN IN IN OUT OUT OUT OUT OUT OUT OUT OUT IN IN IN IN OUT OUT OUT OUT IN IN IN IN OUT OUT OUT OUT IN IN OUT OUT IN IN OUT OUT IN IN OUT OUT IN IN OUT OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT IN OUT Normal Slope Decrease the Slope Approximately 7% Decrease the Slope Approximately 6% Decrease the Slope Approximately 5% Decrease the Slope Approximately 4% Decrease the Slope Approximately 3% Decrease the Slope Approximately 2% Decrease the Slope Approximately 1% Increase the Slope Approximately 1% Increase the Slope Approximately 2% Increase the Slope Approximately 3% Increase the Slope Approximately 4% Increase the Slope Approximately 5% Increase the Slope Approximately 6% Increase the Slope Approximately 7% Normal Slope To improve the accuracy of the system, you can change the constant used by the program that determines the span of the sensor and amplifier. You will need an accurate test gauge (using PSI as the reference) to measure the pressure applied to the sensor. Anytime after the display has completed the zero calculation, (after CAL is no longer displayed) apply the sensor's full scale pressure (see Table 1), to the sensor. Make sure that jumpers J4 through J7 are in the "normal" configuration (see Table 3). Referring to Table 3, you can better "calibrate" the system by changing the configuration of J4 through J7. To "calibrate" the system, compare the display reading against that of the test gauge (with J4 through J7 in the Motorola Sensor Device Data AN1315 "normal slope" configuration). Change the configuration of J4 through J7 according to Table 3 to obtain the best results. The calibration jumpers may be changed while the system is powered up as they are read by the software before each display update. DESIGN CONSIDERATIONS To build a system that will show how to interface an MPX2000 series pressure sensor to a microprocessor, there are two main challenges. The first is to take a small differential signal produced by the sensor and produce a ground referenced signal of sufficient amplitude to drive a microprocessor's A/D input. The second challenge is to understand the microprocessor's operation and to write software that makes the system function. From a hardware point of view, the microprocessor portion of the system is straight forward. The microprocessor needs power, a clock source (crystal Y1, two capacitors and a resistor), and a reset signal to make it function. As for the A/D converter, external references are required to make it function. In this case, the power source for the sensor is divided to produce the voltage references for the A/D converter. Accurate results will be achieved since the output from the sensor and the A/D references are ratiometric to its power supply voltage. The liquid crystal display is driven by Ports A, B and C of the microprocessor. There are enough I/O lines on these ports to provide drive for three full digits, the backplane and two decimal points. Software routines provide the AC waveform necessary to drive the display. The analog portion of the system consists of the pressure sensor, a quad operational amplifier and the voltage references for the microprocessor's A/D converter and signal conditioning circuitry. Figure 4 shows an interface circuit that will provide a single ended signal with sufficient amplitude to drive the microprocessor's A/D input. It uses a quad operational amplifier and several resistors to amplify and level shift the sensor's output. It is necessary to level shift the output from the final amplifier into the A/D. Using single power supplied op amps, the VCE saturation of the output from an op amp cannot be guaranteed to pull down to zero volts. The analog design shown here will provide a signal to the A/D converter with a span of approximately 4 volts when zero to full-scale pressure is applied to the sensor. The final amplifier's output is level shifted to approximately 0.7 volts. This will provide a signal that will swing between approximately 0.7 volts and 4.7 volts. The offset of 0.7 volts in this implementation does not have to be trimmed to an exact point. The software will sample the voltage applied to the A/D converter at initial power up time and call that value "zero". The important thing to remember is that the span of the signal will be approximately 4 volts when zero to full scale pressure is applied to the sensor. The 4 volt swing in signal may vary slightly from sensor to sensor and can also vary due to resistor tolerances in the analog circuitry. Jumpers J4 through J7 may be placed in various configurations to compensate for these variations (see Table 3). www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-247 Freescale Semiconductor, Inc. AN1315 +12 V J8 IS INSTALLED FOR THE MPX2010 ONLY 5 + 4 7 6 -U1A +5 V 6.98K +8 R1 2 3 121 R2 200 R3 D2 PD0 R4 TP1 2K R6 2K 12 + 14 13 -U1D 2 - 1 3 +U1B 11 +8 1N914 4.7K R5 J8 1 4 XDCR1 Freescale Semiconductor, Inc... MC33274 10 + 8 9 -U1C 340 976 1K R9 R10 R7 23.7 R8 Figure 3. Figure 4. Analog Interface Referring to Figure 4, most of the amplification of the voltage from the pressure sensor is provided by U1A which is configured as a differential amplifier. U1B serves as a unity gain buffer in order to keep any current that flows through R2 (and R3) from being fed back into the sensor's negative output. With zero pressure applied to the sensor, the differential voltage from pin 2 to pin 4 of the sensor is zero or very close to zero volts. The common mode, or the voltage measured between pins 2 or 4 to ground, is equal to approximately one half of the voltage applied to the sensor, or 4 volts. The zero pressure output voltage at pin 7 of U1A will then be 4 volts because pin 1 of U1B is also at 4 volts, creating a zero bias between pins 5 and 6 of U1A. The four volt zero pressure output will then be level shifted to the desired zero pressure offset voltage (approximately 0.7 volts) by U1C and U1D. To further explain the operation of the level shifting circuitry, refer again to Figure 4. Assuming zero pressure is applied to the sensor and the common mode voltage from the sensor is 4 volts, the voltage applied to pin 12 of U1D will be 4 volts, implying pin 13 will be at 4 volts. The gain of amplifier U1D will be (R10/(R8+R9)) +1 or a gain of 2. R7 will inject a Voffset (0.7 volts) into amplifier U1D, thus causing the output at U1D pin 14 to be 7.3 = (4 volts @ U1D pin 12 2) - 0.7 volts. The gain of U1C is also set at 2 ((R5/R6)+1). With 4 volts applied to pin 10 of U1C, its output at U1C pin 8 will be 0.7 = ((4 volts @ U1C pin 10 2) - 7.3 volts). For this scheme to work properly, amplifiers U1C and U1D must have a gain of 2 and the output of U1D must be shifted down by the Voffset provided by R7. In this system, the 0.7 volts Voffset was arbitrarily picked and could have been any voltage greater than the Vsat of the op amp being used. The system software will take in account any 3-248 variations of Voffset as it assumes no pressure is applied to the sensor at system power up. The gain of the analog circuit is approximately 117. With the values shown in Figure 4, the gain of 117 will provide a span of approximately 4 volts on U1C pin 8 when the pressure sensor and the 8 volt fixed voltage regulator are at their maximum output voltage tolerance. All of the sensors listed in Table 1 with the exception of the MPX2010DP output approximately 33 mV when full scale pressure is applied. When the MPX2010DP sensor is used, its full scale sensor differential output is approximately 20 mV. J8 must be installed to increase the gain of the analog circuit to still provide the 4 volts span out of U1C pin 8 with a 20 mV differential from the sensor. Diode D2 is used to protect the microprocessor's A/D input if the output from U1C exceeds 5.6 volts. R4 is used to provide current limiting into D4 under failure or overvoltage conditions. SOFTWARE The source code, compiled listing, and S-record output for the software used in this system are available on the Motorola Freeware Bulletin Board Service in the MCU directory under the filename DEVB158.ARC. To access the bulletin board, you must have a telephone line, a 300, 1200 or 2400 baud modem and a personal computer. The modem must be compatible with the Bell 212A standard. Call (512) 891-3733 to access the Bulletin Board Service. Figure 5 is a flowchart for the program that controls the system. The software for the system consists of a number of modules. Their functions provide the capability for system calibration as well as displaying the pressure input to the MPX2000 series pressure sensor. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1315 START INITIALIZE DISPLAY I/O PORTS INITIALIZE TIMER REGISTERS DETERMINE SENSOR TYPE ENABLE INTERRUPTS TIMER INTERRUPT SERVICE TIMER REGISTERS SETUP COUNTER FOR NEXT INTERRUPT SERVICE LIQUID CRYSTAL DISPLAY ACCUMULATE 100 A/D CONVERSIONS COMPUTE INPUT PRESSURE CONVERT TO DECIMAL/SEGMENT DATA PLACE IN RESULT OUTPUT BUFFER RETURN Freescale Semiconductor, Inc... COMPUTE SLOPE CONSTANT Figure 5. DEVB-158 Software Flowchart The "C" compiler used in this project was provided by BYTE CRAFT LTD. (519) 888-6911. A compiler listing of the program is included at the end of this document. The following is a brief explanation of the routines: digit decimal number in an array called "digit." It then uses the decimal results for each digit as an index into a table that converts the decimal number into a segment pattern for the display. This is then output to the display. delay() Used to provide a software loop delay. read_a2d() Performs 100 reads on the A/D converter on multiplexer channel 0 and returns the accumulation. fixcompare() Services the internal timer for 15 ms. timer compare interrupts. TIMERCMP() Alternates the data and backplane inputs to the liquid crystal display. initio() Sets up the microprocessor's I/O ports, timer and enables processor interrupts. adzero() This routine is called at powerup time. It delays to let the power supply and the transducer stabilize. It then calls "read_atod()" and saves the returned value as the sensors output voltage with zero pressure applied. cvt_bin_dec(unsigned long arg) This routine converts the unsigned binary argument passed in "arg" to a five Motorola Sensor Device Data display_psi() This routine is called from "main()" never to return. The A/D converter routine is called, the pressure is calculated based on the type sensor detected and the pressure applied to the sensor is displayed. The loop then repeats. sensor_type() This routine determines the type of sensor from reading J1 to J3, setting the full scale pressure for that particular sensor in a variable for use by display_psi(). sensor_slope() This routine determines the slope constant to be used by display_psi() for engineering units output. main() This is the main routine called from reset. It calls "initio()" to setup the system's I/O. "display_psi()" is called to compute and display the pressure applied to the sensor. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-249 AN1315 6805 'C' COMPILER V3.48 Freescale Semiconductor, Inc. 16-Oct-1991 PAGE 1 #pragma option f0; /* THE FOLLOWING 'C' SOURCE CODE IS WRITTEN FOR THE DEVB158 EVALUATION BOARD. IT WAS COMPILED WITH A COMPILER COURTESY OF: BYTE CRAFT LTD. 421 KING ST. WATERLOO, ONTARIO CANADA N2J 4E4 (519)888-6911 Freescale Semiconductor, Inc... SOME SOURCE CODE CHANGES MAY BE NECESSARY FOR COMPILATION WITH OTHER COMPILERS. BILL LUCAS 2/5/92 MOTOROLA, SPS Revision history rev. 1.0 initial release 3/19/92 rev. 1.1 added additional decimal digit to the MPX2010 sensor. Originally resolved the output to .1 PSI. Modified cvt_bin_dec to output PSI resolved to .01 PSI. WLL 9/25/92 0800 1700 0050 0096 */ #pragma memory ROMPROG [5888] #pragma memory RAMPAGE0 [150] 1FFE 1FFC 1FFA 1FF8 1FF6 1FF4 1FF2 /* #pragma #pragma #pragma #pragma #pragma #pragma #pragma @ 0x0800 ; @ 0x0050 ; Vector assignments */ vector __RESET @ 0x1ffe vector __SWI @ 0x1ffc vector IRQ @ 0x1ffa vector TIMERCAP @ 0x1ff8 vector TIMERCMP @ 0x1ff6 vector TIMEROV @ 0x1ff4 vector SCI @ 0x1ff2 ; ; ; ; ; ; ; #pragma has STOP ; #pragma has WAIT ; #pragma has MUL ; 0000 0001 0002 0003 0004 0005 0006 0007 0008 0009 000A 000B 000C 000D 000E 000F 0010 0011 0012 0013 0014 0015 0016 0017 0018 0019 001A 001B 001C 001D 001E 001F 3-250 /* #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma #pragma Register assignments for the 68HC705B5 microcontroller */ portrw porta @ 0x00; /* */ portrw portb @ 0x01; /* */ portrw portc @ 0x02; /* */ portrw portd @ 0x03; /* in ,- ,SS ,SCK ,MOSI ,MISO,TxD,RxD */ portrw ddra @ 0x04; /* Data direction, Port A */ portrw ddrb @ 0x05; /* Data direction, Port B */ portrw ddrc @ 0x06; /* Data direction, Port C (all output) */ portrw eeclk @ 0x07; /* eeprom/eclk cntl */ portrw addata @ 0x08; /* a/d data register */ portrw adstat @ 0x09; /* a/d stat/control */ portrw plma @ 0x0a; /* pulse length modulation a */ portrw plmb @ 0x0b; /* pulse length modulation b */ portrw misc @ 0x0c; /* miscellaneous register */ portrw scibaud @ 0x0d; /* sci baud rate register */ portrw scicntl1 @ 0x0e; /* sci control 1 */ portrw scicntl2 @ 0x0f; /* sci control 2 */ portrw scistat @ 0x10; /* sci status reg */ portrw scidata @ 0x11; /* SCI Data */ portrw tcr @ 0x12; /* ICIE,OCIE,TOIE,0;0,0,IEGE,OLVL */ portrw tsr @ 0x13; /* ICF,OCF,TOF,0; 0,0,0,0 */ portrw icaphi1 @ 0x14; /* Input Capture Reg (Hi-0x14, Lo-0x15) */ portrw icaplo1 @ 0x15; /* Input Capture Reg (Hi-0x14, Lo-0x15) */ portrw ocmphi1 @ 0x16; /* Output Compare Reg (Hi-0x16, Lo-0x17) */ portrw ocmplo1 @ 0x17; /* Output Compare Reg (Hi-0x16, Lo-0x17) */ portrw tcnthi @ 0x18; /* Timer Count Reg (Hi-0x18, Lo-0x19) */ portrw tcntlo @ 0x19; /* Timer Count Reg (Hi-0x18, Lo-0x19) */ portrw aregnthi @ 0x1A; /* Alternate Count Reg (Hi-$1A, Lo-$1B) */ portrw aregntlo @ 0x1B; /* Alternate Count Reg (Hi-$1A, Lo-$1B) */ portrw icaphi2 @ 0x1c; /* Input Capture Reg (Hi-0x1c, Lo-0x1d) */ portrw icaplo2 @ 0x1d; /* Input Capture Reg (Hi-0x1c, Lo-0x1d) */ portrw ocmphi2 @ 0x1e; /* Output Compare Reg (Hi-0x1e, Lo-0x1f) */ portrw ocmplo2 @ 0x1f; /* Output Compare Reg (Hi-0x1e, Lo-0x1f) */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 1EFE 74 AN1315 #pragma mor @ 0x1efe = 0x74; /* this disables the watchdog counter and does not add pull-down resistors on ports B and C */ /* put constants and variables here...they must be global */ /***************************************************************************/ 0800 FC 30 DA 7A 36 6E E6 38 FE 0809 3E const char lcdtab[]={0xfc,0x30,0xda,0x7a,0x36,0x6e,0xe6,0x38,0xfe,0x3e }; /* lcd pattern table 0 1 2 3 4 5 6 7 8 9 */ 080A 27 10 03 E8 00 64 00 0A const long dectable[] = { 10000, 1000, 100, 10 }; 0050 0005 unsigned int digit[5]; /* buffer to hold results from cvt_bin_dec function */ 0812 00 96 00 4B 00 96 00 1E 00 081B 67 const long type[] = { 150, 75, 150, 30, 103 }; Freescale Semiconductor, Inc... /* MPX2010 MPX2050 MPX2100 MPX2200 MPX2700 The table above will cause the final results of the pressure to engineering units to display the 1.5, 7.3 and 15.0 devices with a decimal place in the tens position. The 30 and 103 psi devices will display in integer units. */ 081C 0825 082E 0837 01 B0 01 DD C2 01 CB 01 01 B4 01 E1 A2 01 CF 01 01 A7 01 AB 01 B9 01 BD 01 C6 01 D4 01 D8 01 C2 const long slope_const[]={ 450,418,423,427,432,436,441,445,454,459, 463,468,472,477,481,450 }; 0000 registera areg; /* processor's A register */ 0055 long atodtemp; /* temp to accumulate 100 a/d readings for smoothing */ 0059 long slope; /* multiplier for adc to engineering units conversion */ 005B int adcnt; /* a/d converter loop counter */ 005C long xdcr_offset; /* initial xdcr offset */ 005E 0060 long sensor_model; /* int sensor_index; /* 0061 0063 unsigned long i,j; /* counter for loops */ 0065 unsigned int k; installed sensor based on J1..J3 */ determine the location of the decimal pt. */ /* misc variable */ struct bothbytes { int hi; { int lo; }; 0066 0002 0066 0002 0066 0002 0066 0002 union isboth { long l; struct bothbytes b; }; union isboth q; /* used for timer set-up */ /***************************************************************************/ 0068 0004 006C 0004 0070 0004 /* variables for add32 */ unsigned long SUM[2]; /* unsigned long ADDEND[2]; /* unsigned long AUGEND[2]; /* result one input second input */ */ */ 0074 0004 0078 0004 007C 0004 /* variables for sub32 */ unsigned long MINUE[2]; /* unsigned long SUBTRA[2]; /* unsigned long DIFF[2]; /* minuend subtrahend difference */ */ */ 0080 0004 0084 0004 0088 0004 /* variables for mul32 */ unsigned long MULTP[2]; /* unsigned long MTEMP[2]; /* unsigned long MULCAN[2]; /* multiplier */ high order 4 bytes at return */ multiplicand at input, low 4 bytes at return */ Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-251 Freescale Semiconductor, Inc. AN1315 /* variables for div32 */ unsigned long DVDND[2]; /* unsigned long DVSOR[2]; /* unsigned long QUO[2]; /* unsigned int CNT; /* 008C 0004 0090 0004 0094 0004 0098 Dividend Divisor Quotient Loop counter */ */ */ */ /* The code starts here */ Freescale Semiconductor, Inc... /***************************************************************************/ 083C 083E 0840 0842 0844 0846 0848 084A 084C 084E 0850 0852 0854 B6 BB B7 B6 B9 B7 B6 B9 B7 B6 B9 B7 81 B6 B0 B7 B6 B2 B7 B6 B2 B7 B6 B2 B7 81 086F 81 RTS void sub32() { #asm *----------------------------------------------------------------------------* * Subtract two 32-bit values. * Input: * Minuend: MINUE[0..3] * Subtrahend: SUBTRA[0..3] * Output: * Difference: DIFF[1..0] *----------------------------------------------------------------------------* * LDA MINUE+3 low byte SUB SUBTRA+3 STA DIFF+3 LDA MINUE+2 medium low byte SBC SUBTRA+2 STA DIFF+2 LDA MINUE+1 medium high byte SBC SUBTRA+1 STA DIFF+1 LDA MINUE high byte SBC SUBTRA STA DIFF RTS done * #endasm } 6F 73 6B 6E 72 6A 6D 71 69 6C 70 68 0855 81 0856 0858 085A 085C 085E 0860 0862 0864 0866 0868 086A 086C 086E RTS void add32() { #asm *----------------------------------------------------------------------------* * Add two 32-bit values. * Inputs: * ADDEND: ADDEND[0..3] HIGH ORDER BYTE IS ADDEND+0 * AUGEND: AUGEND[0..3] HIGH ORDER BYTE IS AUGEND+0 * Output: * SUM: SUM[0..3] HIGH ORDER BYTE IS SUM+0 *----------------------------------------------------------------------------* * LDA ADDEND+3 low byte ADD AUGEND+3 STA SUM+3 LDA ADDEND+2 medium low byte ADC AUGEND+2 STA SUM+2 LDA ADDEND+1 medium high byte ADC AUGEND+1 STA SUM+1 LDA ADDEND high byte ADC AUGEND STA SUM RTS done * #endasm } 77 7B 7F 76 7A 7E 75 79 7D 74 78 7C void mul32() { #asm *----------------------------------------------------------------------------* * Multiply 32-bit value by a 32-bit value * * * Input: 3-252 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 0870 0872 0874 0876 0878 087A 087C 087E 0880 0882 0884 0886 0888 088A 088C 088E 0890 0892 0894 0896 0898 089A 089C 089E 08A0 08A2 08A4 08A6 08A8 08AA 08AC 08AD 08AF AE 3F 3F 3F 3F 36 36 36 36 24 B6 BB B7 B6 B9 B7 B6 B9 B7 B6 B9 B7 36 36 36 36 36 36 36 36 5A 26 81 * Multiplier: MULTP[0..3] * Multiplicand: MULCAN[0..3] * Output: * Product: MTEMP[0..3] AND MULCAN[0..3] MTEMP[0] IS THE HIGH * ORDER BYTE AND MULCAN[3] IS THE LOW ORDER BYTE * * THIS ROUTINE DOES NOT USE THE MUL INSTRUCTION FOR THE SAKE OF USERS NOT * USING THE HC(7)05 SERIES PROCESSORS. *----------------------------------------------------------------------------* * * LDX #32 loop counter CLR MTEMP clean-up for result CLR MTEMP+1 * CLR MTEMP+2 * CLR MTEMP+3 * ROR MULCAN low but to carry, the rest one to the right ROR MULCAN+1 * ROR MULCAN+2 * ROR MULCAN+3 * MNEXT BCC ROTATE if carry is set, do the add LDA MTEMP+3 * ADD MULTP+3 * STA MTEMP+3 * LDA MTEMP+2 * ADC MULTP+2 * STA MTEMP+2 * LDA MTEMP+1 * ADC MULTP+1 * STA MTEMP+1 * LDA MTEMP * ADC MULTP * STA MTEMP * ROTATE ROR MTEMP else: shift low bit to carry, the rest to the right ROR MTEMP+1 * ROR MTEMP+2 * ROR MTEMP+3 * ROR MULCAN * ROR MULCAN+1 * ROR MULCAN+2 * ROR MULCAN+3 * DEX bump the counter down BNE MNEXT done yet ? RTS done 20 84 85 86 87 88 89 8A 8B 18 87 83 87 86 82 86 85 81 85 84 80 84 84 85 86 87 88 89 8A 8B D3 08B0 81 AN1315 #endasm } RTS void div32() { #asm 08B1 08B3 08B5 08B7 08B9 08BB 08BD 3F 3F 3F 3F A6 3D 2B 94 95 96 97 01 90 0F 08BF 08C0 08C2 08C4 08C6 08C8 4C 38 39 39 39 2B 93 92 91 90 04 * *----------------------------------------------------------------------------* * Divide 32 bit by 32 bit unsigned integer routine * * Input: * Dividend: DVDND [+0..+3] HIGH ORDER BYTE IS DVND+0 * Divisor: DVSOR [+0..+3] HIGH ORDER BYTE IS DVSOR+0 * Output: * Quotient: QUO [+0..+3] HIGH ORDER BYTE IS QUO+0 *----------------------------------------------------------------------------* * CLR QUOzero result registers CLR QUO+1 * CLR QUO+2 * CLR QUO+3 * LDA #1 initial loop count TST DVSOR if the high order bit is set..no need to shift DVSOR BMI DIV153 * DIV151 INCA bump the loop counter ASL DVSOR+3 now shift the divisor until the high order bit = 1 ROL DVSOR+2 ROL DVSOR+1 * ROL DVSOR * BMI DIV153 done if high order bit = 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-253 Freescale Semiconductor, Inc. AN1315 08CA A1 21 08CC 26 F1 * DIV153 * DIV163 08CE B7 98 08D0 08D2 08D4 08D6 08D8 08DA 08DC 08DE 08E0 08E2 08E4 08E6 08E8 B6 B0 B7 B6 B2 B7 B6 B2 B7 B6 B2 B7 24 8F 93 8F 8E 92 8E 8D 91 8D 8C 90 8C 1B 08EA 08EC 08EE 08F0 08F2 08F4 08F6 08F8 08FA 08FC 08FE 0900 0902 B6 BB B7 B6 B9 B7 B6 B9 B7 B6 B9 B7 98 8F 93 8F 8E 92 8E 8D 91 8D 8C 90 8C 0903 0905 0906 0908 090A 090C 090E 0910 0912 0914 0916 0918 091A 20 99 39 39 39 39 34 36 36 36 3A 26 81 01 CMP BNE #33 DIV151 have we shifted all possible bits in the DVSOR yet ? no STA CNT save the loop counter so we can do the divide LDA SUB STA LDA SBC STA LDA SBC STA LDA SBC STA BCC DVDND+3 DVSOR+3 DVDND+3 DVDND+2 DVSOR+2 DVDND+2 DVDND+1 DVSOR+1 DVDND+1 DVDND DVSOR DVDND DIV165 sub 32 bit divisor from dividend * * * * * * * * * * * carry is clear if DVSOR was larger than DVDND LDA ADD STA LDA ADC STA LDA ADC STA LDA ADC STA CLC DVDND+3 DVSOR+3 DVDND+3 DVDND+2 DVSOR+2 DVDND+2 DVDND+1 DVSOR+1 DVDND+1 DVDND DVSOR DVDND add the divisor back...was larger than the dividend * * * * * * * * * * * this will clear the respective bit in QUO due to the need to add DVSOR back to DVND Freescale Semiconductor, Inc... * * DIV165 DIV167 97 96 95 94 90 91 92 93 98 B6 BRA DIV167 SEC ROL QUO+3 ROL QUO+2 ROL QUO+1 ROL QUO LSR DVSOR ROR DVSOR+1 ROR DVSOR+2 ROR DVSOR+3 DEC CNT BNE DIV163 RTSyes this will set the respective bit in QUO set or clear the low order bit in QUO based on above * * * divide the divisor by 2 * * * bump the loop counter down finished yet ? * 091B 81 #endasm } RTS /***************************************************************************/ /* These interrupts are not used...give them a graceful return if for some reason one occurs */ 1FFC 091C 1FFA 091D 1FF8 091E 1FF4 091F 1FF2 0920 09 80 09 80 09 80 09 80 09 80 1C __SWI(){} RTI 1D IRQ(){} RTI 1E TIMERCAP(){} RTI 1F TIMEROV(){} RTI 20 SCI(){} RTI /***************************************************************************/ 0921 0923 0925 0927 0929 092B B6 A4 B7 34 B6 A1 3-254 03 0E 65 65 65 04 LDA AND STA LSR LDA CMP $03 #$0E $65 $65 $65 #$04 void sensor_type() { k = portd & 0x0e; /* we only care about bits 1..3 */ k = k >> 1; if ( k > 4 ) /* right justify the variable */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 092D 23 0C BLS $093B 092F 0931 0933 0935 0937 0939 3F A6 B7 A6 B7 20 02 6E 01 CE 00 FE CLR LDA STA LDA STA BRA $02 #$6E $01 #$CE $00 $0939 093B 093D 093F 0940 0941 0944 0946 0949 094B B6 B7 97 58 D6 B7 D6 B7 81 65 60 LDA STA TAX LSLX LDA STA LDA STA RTS $65 $60 08 12 5E 08 13 5F AN1315 { /* we have a set-up error in wire jumpers J1 - J3 */ portc = 0; /* */ portb = 0x6e; /* S */ porta = 0xce; /* E */ while(1); } sensor_index = k; sensor_model = type[k]; $0812,X $5E $0813,X $5F } Freescale Semiconductor, Inc... /***************************************************************************/ 094C 094E 0950 0952 0954 0956 0958 095A 095C 095D 0960 0962 0965 0967 B6 A4 B7 34 34 34 34 BE 58 D6 B7 D6 B7 81 03 F0 65 65 65 65 65 65 08 1C 59 08 1D 5A LDA AND STA LSR LSR LSR LSR LDX LSLX LDA STA LDA STA RTS $03 #$F0 $65 $65 $65 $65 $65 $65 void sensor_slope() { k=portd & 0xf0; /* we only care about bits 4..7 */ k = k >> 4; /* right justify the variable */ slope = slope_const[k]; $081C,X $59 $081D,X $5A } /***************************************************************************/ 0968 096A 096C 096E 0970 0972 0974 0976 0978 097A 097C 097E 3F 3F B6 A0 B6 A2 24 3C 26 3C 20 81 62 61 62 20 61 4E 08 62 02 61 EE CLR CLR LDA SUB LDA SBC BCC INC BNE INC BRA RTS $62 $61 $62 #$20 $61 #$4E $097E $62 $097C $61 $096C void delay(void) /* just hang around for a while */ { for (i=0; i<20000; ++i); } /***************************************************************************/ read_a2d(void) { /* read the a/d converter on channel 5 and accumulate the result in atodtemp */ 097F 0981 0983 0985 0987 0989 098B 3F 3F 3F B6 A8 A1 24 56 55 5B 5B 80 E4 21 CLR CLR CLR LDA EOR CMP BCC $56 $55 $5B $5B #$80 #$E4 $09AE 098D 098F 0991 0994 0996 0998 A6 B7 0F B6 3F B7 20 09 09 FD 08 57 58 LDA #$20 STA $09 BRCLR 7,$09,$0991 LDA $08 CLR $57 STA $58 Motorola Sensor Device Data atodtemp=0; /* zero for accumulation */ for ( adcnt = 0 ; adcnt<100; ++adcnt) /* do 100 a/d conversions */ { adstat = 0x20; /* convert on channel 0 */ while (!(adstat & 0x80)); /* wait for a/d to complete */ atodtemp = addata + atodtemp; www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-255 Freescale Semiconductor, Inc. AN1315 099A 099C 099E 09A0 09A2 09A4 09A6 09A8 BB B7 B6 B9 B7 B7 B6 B7 56 58 57 55 57 55 58 56 ADD STA LDA ADC STA STA LDA STA $56 $58 $57 $55 $57 $55 $58 $56 09AA 09AC 09AE 09B0 09B2 09B4 09B6 09B8 09BA 09BC 09BF 09C2 09C4 09C6 3C 20 B6 B7 B6 B7 3F A6 B7 CD CD BF B7 81 5B D7 56 58 55 57 9A 64 9B 0B F1 0C 22 55 56 INC BRA LDA STA LDA STA CLR LDA STA JSR JSR STX STA RTS $5B $0985 $56 $58 $55 $57 $9A #$64 $9B $0BF1 $0C22 $55 $56 Freescale Semiconductor, Inc... } atodtemp = atodtemp/100; return atodtemp; } /***************************************************************************/ 09C7 09C9 09CB 09CD 09CF 09D1 09D3 09D5 09D7 09D9 09DB 09DD 09DF 09E1 B6 B7 B6 B7 AB B7 B6 A9 B7 B7 B6 B6 B7 81 18 66 19 67 4C 67 66 1D 66 16 13 67 17 LDA STA LDA STA ADD STA LDA ADC STA STA LDA LDA STA RTS $18 $66 $19 $67 #$4C $67 $66 #$1D $66 $16 $13 $67 $17 void fixcompare (void) { q.b.hi =tcnthi; /* sets-up the timer compare for the next interrupt */ q.b.lo = tcntlo; q.l +=7500; /* ((4mhz xtal/2)/4) = counter period = 2us.*7500 = 15ms. */ ocmphi1 = q.b.hi; areg=tsr; /* dummy read */ ocmplo1 = q.b.lo; } /***************************************************************************/ 1FF6 09E2 09E4 09E6 09E8 09EA 09 33 33 33 AD 80 E2 02 01 00 DD COM COM COM BSR RTI $02 $01 $00 $09C7 void TIMERCMP (void) /* timer service module */ { portc =~ portc; /* service the lcd by inverting the ports */ portb =~ portb; porta =~ porta; fixcompare(); } /***************************************************************************/ void adzero(void) /* called by initio() to save initial xdcr's zero pressure offset voltage output */ { 09EB 09ED 09EF 09F1 09F3 09F5 09F7 3F 3F B6 A0 B6 A2 24 64 63 64 14 63 00 0B CLR CLR LDA SUB LDA SBC BCC $64 $63 $64 #$14 $63 #$00 $0A04 for ( j=0; j<20; ++j) /* give the sensor time to "warm-up" and the power supply time to settle down */ { 09F9 CD 09 68 JSR $0968 delay(); } 09FC 09FE 0A00 0A02 0A04 3C 26 3C 20 CD 3-256 64 02 63 EB 09 7F INC BNE INC BRA JSR $64 $0A02 $63 $09EF $097F xdcr_offset = read_a2d(); www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 0A07 3F 5C 0A09 B7 5D 0A0B 81 CLR STA RTS AN1315 $5C $5D } Freescale Semiconductor, Inc... /***************************************************************************/ 0A0C 0A0E 0A10 0A12 0A14 0A16 0A18 0A1A 0A1C 0A1E 0A20 0A22 0A24 0A26 0A28 0A2A 0A2C A6 B7 3F 3F 3F A6 B7 B7 B7 B6 3F 3F B6 AD A6 B7 9A 20 09 02 01 00 FF 06 05 04 13 1E 16 1F 9F 40 12 0A2D 0A2F 0A31 0A33 0A35 0A37 0A39 0A3C 0A3E A6 B7 A6 B7 A6 B7 CD AD 81 CC 02 BE 01 C4 00 09 21 AD LDA STA CLR CLR CLR LDA STA STA STA LDA CLR CLR LDA BSR LDA STA CLI #$20 $09 $02 $01 $00 #$FF $06 $05 $04 $13 $1E $16 $1F $09C7 #$40 $12 LDA STA LDA STA LDA STA JSR BSR RTS #$CC $02 #$BE $01 #$C4 $00 $0921 $09EB void initio (void) /* setup the I/O */ { adstat = 0x20; /* power-up the A/D */ porta = portb = portc = 0; ddra = ddrb = ddrc = 0xff; areg=tsr; /* dummy read */ ocmphi1 = ocmphi2 = 0; areg = ocmplo2; /* clear out output compare 2 if it happens to be set */ fixcompare(); /* set-up for the first timer interrupt */ tcr = 0x40; CLI; /* let the interrupts begin ! /* write CAL to the display */ portc = 0xcc; /* C */ */ portb = 0xbe; /* A */ porta = 0xc4; /* L */ sensor_type(); /* get the model of the sensor based on J1..J3 */ adzero(); /* auto zero */ } /***************************************************************************/ void cvt_bin_dec(unsigned long arg) /* First converts the argument to a five digit decimal value. The msd is in the lowest address. Then leading zero suppress the value and write it to the display ports. The argument value is 0..65535 decimal. */ 009D 0A3F 0A41 009F 00A0 0A43 0A45 0A47 0A49 { BF 9D B7 9E 3F B6 A1 24 STX STA $9D $9E 9F 9F 05 07 CLR LDA CMP BCC $9F $9F #$05 $0A52 0A4B 97 0A4C 6F 50 TAX CLR $50,X 0A4E 0A50 0A52 0A54 0A56 0A58 3C 20 3F B6 A1 24 9F F3 9F 9F 04 7A INC BRA CLR LDA CMP BCC $9F $0A45 $9F $9F #$04 $0AD4 0A5A 0A5B 0A5C 0A5F 0A61 0A63 0A65 0A67 0A69 0A6C 0A6E 97 58 D6 B0 B7 B6 A8 B7 D6 A8 B2 08 0B 9E 58 9D 80 57 08 0A 80 57 TAX LSLX LDA SUB STA LDA EOR STA LDA EOR SBC char i; unsigned long l; for ( i=0; i < 5; ++i ) { digit[i] = 0x0; /* put blanks in all digit positions */ } for ( i=0; i < 4; ++i ) { if ( arg >= dectable [i] ) $080B,X $9E $58 $9D #$80 $57 $080A,X #$80 $57 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-257 Freescale Semiconductor, Inc. AN1315 0A70 BA 58 0A72 22 5C ORA BHI $58 $0AD0 0A74 0A76 0A77 0A7A 0A7C 0A7F 0A81 0A83 0A85 0A87 0A89 0A8B 0A8D 0A8F 0A91 0A94 0A97 0A99 0A9B 0A9D 0A9F 0AA1 0AA3 0AA5 0AA7 0AA9 0AAB 0AAD 0AAF 0AB2 0AB4 0AB6 0AB8 0ABA 0ABC 0ABE 0AC0 0AC2 0AC4 0AC6 0AC8 0ACA 0ACC 0ACE LDX LSLX LDA STA LDA STA LDA STA LDA STA LDA STA LDA STA JSR JSR STX STA LDX STA LDX LDA CLR STA LDA STA LDA STA JSR STX STA COM NEG BNE INC LDA ADD STA LDA ADC STA STA LDA STA $9F Freescale Semiconductor, Inc... { BE 58 D6 B7 D6 B7 B6 B7 B6 B7 B6 B7 B6 B7 CD CD BF B7 BE E7 BE E6 3F B7 B6 B7 B6 B7 CD BF B7 33 30 26 3C B6 BB B7 B6 B9 B7 B7 B6 B7 9F 08 A0 08 A1 9E 58 9D 57 A0 9A A1 9B 0B 0C 57 58 9F 50 9F 50 57 58 A0 9A A1 9B 0B 57 58 57 58 02 57 58 9E 58 57 9D 57 9D 58 9E 0A 0B F1 22 D2 l = dectable[i]; $080A,X $A0 $080B,X $A1 $9E $58 $9D $57 $A0 $9A $A1 $9B $0BF1 $0C22 $57 $58 $9F $50,X $9F $50,X $57 $58 $A0 $9A $A1 $9B $0BD2 $57 $58 $57 $58 $0ABE $57 $58 $9E $58 $57 $9D $57 $9D $58 $9E digit[i] = arg / l; arg = arg-(digit[i] * l); } } 0AD0 0AD2 0AD4 0AD6 0AD8 0ADA 0ADC 0ADE 0AE0 3C 20 B6 B7 B6 B7 BE B6 E7 0AE2 0AE3 0AE5 0AE7 0AE9 0AEB 0AED 0AF0 0AF2 0AF4 0AF6 0AF8 0AFA 0AFC 0AFE 0B00 9B 3D 26 3F 20 BE D6 B7 3D 26 3D 26 3F 20 BE D6 3-258 9F 80 9E 58 9D 57 9F 58 50 INC BRA LDA STA LDA STA LDX LDA STA 52 04 02 07 52 08 00 02 52 08 53 04 01 07 53 08 00 SEI TST BNE CLR BRA LDX LDA STA TST BNE TST BNE CLR BRA LDX LDA $9F $0A54 $9E $58 $9D $57 $9F $58 $50,X $52 $0AEB $02 $0AF2 $52 $0800,X $02 $52 $0AFE $53 $0AFE $01 $0B05 $53 $0800,X digit[i] = arg; /* now zero suppress and send the lcd pattern to the display */ SEI; if ( digit[2] == 0 ) /* leading zero suppression */ portc = 0; else portc = ( lcdtab[digit[2]] ); /* 100's digit */ if ( digit[2] == 0 && digit[3] == 0 ) portb=0; else portb = ( lcdtab[digit[3]] ); /* 10's digit */ www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 0B03 0B05 0B07 0B0A B7 BE D6 B7 01 54 08 00 00 STA LDX LDA STA $01 $54 $0800,X $00 0B0C 0B0E 0B10 0B12 0B14 0B16 0B19 0B1A 0B1C 0B1E B6 A8 A1 24 BE D6 4C B7 3D 26 60 80 83 08 54 08 00 LDA EOR CMP BCC LDX LDA INCA STA TST BNE $60 #$80 #$83 $0B1C $54 $0800,X 0B20 0B22 0B25 0B27 0B29 0B2C 0B2D BE D6 B7 BE D6 4C B7 00 60 0F 54 08 00 00 53 08 00 01 LDX LDA STA LDX LDA INCA STA porta = ( lcdtab[digit[4]] ); AN1315 /* 1's digit */ /* place the decimal point only if the sensor is 15 psi or 7.5 psi */ if ( sensor_index < 3 ) porta = ( lcdtab[digit[4]]+1 ); /* add the decimal point to the lsd */ $00 $60 $0B2F if(sensor_index ==0) /* special case */ { porta = ( lcdtab[digit[4]] ); /* get rid of the decimal at lsd */ $54 $0800,X $00 $53 $0800,X portb = ( lcdtab[digit[3]]+1 ); /* decimal point at middle digit */ $01 } 0B2F 9A 0B30 CD 09 68 0B33 81 CLI JSR RTS CLI; $0968 delay(); } /****************************************************************/ void display_psi(void) /* At power-up it is assumed that the pressure or vacuum port of the sensor is open to atmosphere. The code in initio() delays for the sensor and power supply to stabilize. One hundred A/D conversions are averaged. That result is called xdcr_offset. This routine calls the A/D routine which performs one hundred conversions, divides the result by 100 and returns the value. If the value returned is less than or equal to the xdcr_offset, the value of xdcr_offset is substituted. If the value returned is greater than xdcr_offset, xdcr_offset is subtracted from the returned value. */ 0B34 0B37 0B39 0B3B 0B3D 0B3F 0B41 0B43 0B45 0B47 0B49 0B4B 0B4D 0B4F 0B51 0B53 0B55 0B57 0B59 0B5B 0B5D 0B5F 0B61 0B63 0B66 0B68 0B6A 0B6C 0B6E CD 3F B7 B0 B7 B6 A8 B7 B6 A8 B2 BA 22 B6 B7 B6 B7 B6 B0 B7 B6 B2 B7 CD B6 B7 B6 B7 B6 09 7F 55 56 5D 58 5C 80 57 55 80 57 58 08 5C 55 5D 56 56 5D 56 55 5C 55 09 4C 56 58 55 57 5E JSR CLR STA SUB STA LDA EOR STA LDA EOR SBC ORA BHI LDA STA LDA STA LDA SUB STA LDA SBC STA JSR LDA STA LDA STA LDA $097F $55 $56 $5D $58 $5C #$80 $57 $55 #$80 $57 $58 $0B57 $5C $55 $5D $56 $56 $5D $56 $55 $5C $55 $094C $56 $58 $55 $57 $5E Motorola Sensor Device Data { while(1) { atodtemp = read_a2d(); /* atodtemp = raw a/d ( 0..255 ) */ if ( atodtemp <= xdcr_offset ) atodtemp = xdcr_offset; atodtemp -= xdcr_offset; /* remove the offset */ sensor_slope(); /* establish the slope constant for this output */ atodtemp *= sensor_model; www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-259 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1315 0B70 0B72 0B74 0B76 0B79 0B7B 0B7D 0B7F 0B81 0B83 0B85 0B86 0B88 0B8A 0B8C 0B8E 0B90 0B92 0B94 0B97 0B99 0B9B 0B9D 0B9F 0BA1 0BA3 0BA5 0BA7 0BA9 0BAB 0BAD 0BAF 0BB1 0BB3 0BB5 0BB8 0BBA 0BBC 0BBE 0BC0 0BC2 0BC5 0BC8 B7 B6 B7 CD BF B7 3F 3F 3F 3F 9F B7 B6 B7 B6 B7 B6 B7 CD 3F A6 B7 A6 B7 A6 B7 B6 B7 B6 B7 B6 B7 B6 B7 CD B6 B7 B6 B7 BE CD CC 81 9A 5F 9B 0B D2 55 56 89 88 81 80 82 56 83 59 8A 5A 8B 08 90 01 91 86 92 A0 93 88 8C 89 8D 8A 8E 8B 8F 08 96 55 97 56 55 0A 0B 70 B1 3F 34 STA LDA STA JSR STX STA CLR CLR CLR CLR TXA STA LDA STA LDA STA LDA STA JSR CLR LDA STA LDA STA LDA STA LDA STA LDA STA LDA STA LDA STA JSR LDA STA LDA STA LDX JSR JMP RTS $9A $5F $9B $0BD2 $55 $56 $89 $88 $81 $80 MULTP[0] = MULCAN[0] = 0; MULTP[1] = atodtemp; $82 $56 $83 $59 $8A $5A $8B $0870 $90 #$01 $91 #$86 $92 #$A0 $93 $88 $8C $89 $8D $8A $8E $8B $8F $08B1 $96 $55 $97 $56 $55 $0A3F $0B34 MULCAN[1] = slope; mul32(); /* analog value * slope based on J1 through J3 */ DVSOR[0] = 1; /* now divide by 100000 */ DVSOR[1] = 0x86a0; DVDND[0] = MULCAN[0]; DVDND[1] = MULCAN[1]; div32(); atodtemp = QUO[1]; /* convert to psi */ cvt_bin_dec( atodtemp ); /* convert to decimal and display */ } } /***************************************************************************/ 0BC9 0BCC 0BCF 0BD1 0BD2 0BD4 0BD6 0BD7 0BD9 0BDB 0BDD 0BDF 0BE0 0BE2 0BE4 0BE6 0BE8 0BE9 0BEB 0BED 0BEE 0BF0 0BF1 0BF3 0BF4 0BF6 0BF8 0BF9 CD CD 20 81 BE B6 42 B7 BF BE B6 42 BB B7 BE B6 42 BB B7 97 B6 81 3F 5F 3F 3F 5C 38 3-260 0A 0C 0B 34 FE 58 9B A4 A5 57 9B A5 A5 58 9A A5 A5 A4 A4 A2 A3 58 JSR JSR BRA RTS LDX LDA MUL STA STX LDX LDA MUL ADD STA LDX LDA MUL ADD STA TAX LDA RTS CLR CLRX CLR CLR INCX LSL $0A0C $0B34 $0BCF void main() { initio(); /* set-up the processor's i/o */ display_psi(); while(1); /* should never get back to here */ } $58 $9B $A4 $A5 $57 $9B $A5 $A5 $58 $9A $A5 $A5 $A4 $A4 $A2 $A3 $58 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 0BFB 0BFD 0BFF 0C01 0C03 0C05 0C07 0C09 0C0B 0C0D 0C0F 0C11 0C13 0C15 0C17 0C19 0C1B 0C1C 0C1D 0C1F 0C21 0C22 0C23 0C24 0C26 0C27 1FFE 39 39 39 B6 B0 B7 B6 B2 B7 24 B6 BB B7 B6 B9 B7 99 59 39 24 81 53 9F BE 53 81 0B 57 A2 A3 A2 9B A2 A3 9A A3 0D 9B A2 A2 9A A3 A3 A4 D8 A4 ROL ROL ROL LDA SUB STA LDA SBC STA BCC LDA ADD STA LDA ADC STA SEC ROLX ROL BCC RTS COMX TXA LDX COMX RTS AN1315 $57 $A2 $A3 $A2 $9B $A2 $A3 $9A $A3 $0C1C $9B $A2 $A2 $9A $A3 $A3 $A4 $0BF9 $A4 C9 SYMBOL TABLE LABEL VALUE LABEL VALUE LABEL VALUE LABEL VALUE ADDEND DIV151 DIV167 MINUE MULTP SUBTRA TIMEROV __MUL __STARTUP __longAC adstat arg cvt_bin_dec dectable div32 i icaplo2 k main ocmphi2 plmb portd scicntl1 sensor_index slope tcntlo xdcr_offset 006C 08BF 0906 0074 0080 0078 091F 0000 0000 0057 0009 009D 0A3F 080A 08B1 0061 001D 0065 0BC9 001E 000B 0003 000E 0060 0059 0019 005C AUGEND DIV153 DVDND MNEXT QUO SUM __LDIV __MUL16x16 __STOP adcnt adzero atodtemp ddra delay eeclk icaphi1 initio l misc ocmplo1 porta q scicntl2 sensor_model slope_const tcr 0070 08CE 008C 0882 0094 0068 0BF1 0BD2 0000 005B 09EB 0055 0004 0968 0007 0014 0A0C 0000 000C 0017 0000 0066 000F 005E 081C 0012 CNT DIV163 DVSOR MTEMP ROTATE TIMERCAP __LongIX __RDIV __SWI add32 aregnthi b ddrb digit fixcompare icaphi2 isboth lcdtab mul32 ocmplo2 portb read_a2d scidata sensor_slope sub32 tsr 0098 08D0 0090 0084 089C 091E 009A 0C22 091C 083C 001A 0000 0005 0050 09C7 001C 0002 0800 0870 001F 0001 097F 0011 094C 0856 0013 DIFF DIV165 IRQ MULCAN SCI TIMERCMP __MAIN __RESET __WAIT addata aregntlo bothbytes ddrc display_psi hi icaplo1 j lo ocmphi1 plma portc scibaud scistat sensor_type tcnthi type 007C 0905 091D 0088 0920 09E2 0BC9 1FFE 0000 0008 001B 0002 0006 0B34 0000 0015 0063 0001 0016 000A 0002 000D 0010 0921 0018 0812 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MEMORY USAGE MAP ('X' = Used, '-' = Unused) 0800 0840 0880 08C0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0900 0940 0980 09C0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0A00 0A40 0A80 0AC0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-261 Freescale Semiconductor, Inc. AN1315 0B00 0B40 0B80 0BC0 : : : : XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX 0C00 0C40 0C80 0CC0 : : : : XXXXXXXXXXXXXXXX ---------------- ---------------- ---------------- XXXXXXXXXXXXXXXX ---------------- ---------------- ---------------- XXXXXXXX-------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- 1E00 1E40 1E80 1EC0 : : : : ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- --------------X- 1F00 1F40 1F80 1FC0 : : : : ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- --XXXXXXXXXXXXXX Freescale Semiconductor, Inc... All other memory blocks unused. Errors Warnings 3-262 : : 0 0 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1316 Frequency Output Conversion for MPX2000 Series Pressure Sensors Prepared by: Jeff Baum Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Typically, a semiconductor pressure transducer converts applied pressure to a "low-level" voltage signal. Current technology enables this sensor output to be temperature compensated and amplified to higher voltage levels on a single silicon integrated circuit (IC). While on-chip temperature compensation and signal conditioning certainly provide a significant amount of added value to the basic sensing device, one must also consider how this final output will be used and/or interfaced for further processing. In most sensing systems, the sensor signal will be input to additional analog circuitry, control logic, or a microcontroller unit (MCU). MCU-based systems have become extremely cost effective. The level of intelligence which can be obtained for only a couple of dollars, or less, has made relatively simple 8-bit microcontrollers the partner of choice for semiconductor pressure transducers. In order for the sensor to communicate its pressure-dependent voltage signal to the microprocessor, the MCU must have an analog-to-digital converter (A/D) as an on-chip resource or an additional IC packaged A/D. In the latter case, the A/D must have a communications interface that is compatible with one of the MCU's communications protocols. MCU's are adept at detecting logic-level transitions that occur at input pins designated for screening such events. As an alternative to the conventional A/D sensor/MCU interface, one can measure either a period (frequency) or pulse width of an incoming square or rectangular wave signal. Common MCU timer subsystem clock frequencies permit temporal measurements with resolution of hundreds of nanoseconds. Thus, one is capable of accurately measuring the the frequency output of a device that is interfaced to such a timer channel. If sensors can provide a frequency modulated signal that is linearly proportional to the applied pressure being measured, then an accurate, inexpensive (no A/D) MCU-based sensor system is a viable solution to many challenging sensing applications. Besides the inherent cost savings of such a system, this design concept offers additional benefits to remote sensing applications and sensing in electrically noisy environments. Figure 1. DEVB160 Frequency Output Sensor EVB (Board No Longer Available) REV 2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-263 AN1316 Freescale Semiconductor, Inc. The following sections will detail the design issues involved in such a system architecture, and will provide an example circuit which has been developed as an evaluation tool for frequency output pressure sensor applications. Freescale Semiconductor, Inc... DESIGN CONSIDERATIONS Signal Conditioning Motorola's MPX2000 Series sensors are temperature compensated and calibrated - i.e. - offset and full-scale span are precision trimmed - pressure transducers. These sensors are available in full-scale pressure ranges from 10 kPa (1.5 psi) to 200 kPa (30 psi). Although the specifications in the data sheets apply only to a 10 V supply voltage, the output of these devices is ratiometric with the supply voltage. At the absolute maximum supply voltage specified, 16 V, the sensor will produce a differential output voltage of 64 mV at the rated full-scale pressure of the given sensor. One exception to this is that the full-scale span of the MPX2010 (10 kPa sensor) will be only 40 mV due to a slightly lower sensitivity. Since the maximum supply voltage produces the most output voltage, it is evident that even the best case scenario will require some signal conditioning to obtain a usable voltage level. Many different "instrumentation-type" amplifier circuits can satisfy the signal conditioning needs of these devices. Depending on the precision and temperature performance demanded by a given application, one can design an amplifier circuit using a wide variety of operational amplifier (op amp) IC packages with external resistors of various tolerances, or a precision-trimmed integrated instrumentation amplifier IC. In any case, the usual goal is to have a single-ended supply, "rail-to-rail" output (i.e. use as much of the range from ground to the supply voltage as possible, without saturating the op amps). In addition, one may need the flexibility of performing zero-pressure offset adjust and full-scale pressure calibration. The circuitry or device used to accomplish the voltage-to-frequency conversion will determine if, how, and where calibration adjustments are needed. See Evaluation Board Circuit Description section for details. Voltage-to-Frequency Conversion Since most semiconductor pressure sensors provide a voltage output, one must have a means of converting this voltage signal to a frequency that is proportional to the sensor output voltage. Assuming the analog voltage output of the sensor is proportional to the applied pressure, the resultant 3-264 frequency will be linearly related to the pressure being measured. There are many different timing circuits that can perform voltage-to-frequency conversion. Most of the "simple" (relatively low number of components) circuits do not provide the accuracy or the stability needed for reliably encoding a signal quantity. Fortunately, many voltage-to-frequency (V/F) converter IC's are commercially available that will satisfy this function. Switching Time Reduction One limitation of some V/F converters is the less than adequate switching transition times that effect the pulse or square-wave frequency signal. The required switching speed will be determined by the hardware used to detect the switching edges. The Motorola family of microcontrollers have input-capture functions that employ "Schmitt trigger-like" inputs with hysteresis on the dedicated input pins. In this case, slow rise and fall times will not cause an input capture pin to be in an indeterminate state during a transition. Thus, CMOS logic instability and significant timing errors will be prevented during slow transitions. Since the sensor's frequency output may be interfaced to other logic configurations, a designer's main concern is to comply with a worst-case timing scenario. For high-speed CMOS logic, the maximum rise and fall times are typically specified at several hundreds of nanoseconds. Thus, it is wise to speed up the switching edges at the output of the V/F converter. A single small-signal FET and a resistor are all that is required to obtain switching times below 100 ns. APPLICATIONS Besides eliminating the need for an A/D converter, a frequency output is conducive to applications in which the sensor output must be transmitted over long distances, or when the presence of noise in the sensor environment is likely to corrupt an otherwise healthy signal. For sensor outputs encoded as a voltage, induced noise from electromagnetic fields will contaminate the true voltage signal. A frequency signal has greater immunity to these noise sources and can be effectively filtered in proximity to the MCU input. In other words, the frequency measured at the MCU will be the frequency transmitted at the output of a sensor located remotely. Since high-frequency noise and 50-60 Hz line noise are the two most prominent sources for contamination of instrumentation signals, a frequency signal with a range in the low end of the kHz spectrum is capable of being well filtered prior to being examined at the MCU. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1316 Table 1. Specifications Characteristics Max Units 30 Volts - MPX2010 10 kPa - MPX2050 50 kPa - MPX2100 100 kPa - MPX2200 200 kPa Power Supply Voltage Full Scale Pressure Min B+ 10 Zero Pressure Offset Sensitivity Quiescent Current fFS 10 kHz fOFF 1 kHz SAOUT 9/PFS kHz/kPa ICC 55 mA EVALUATION BOARD The following sections present an example of the signal conditioning, including frequency conversion, that was developed as an evaluation tool for the Motorola MPX2000 series pressure sensors. A summary of the information required to use evaluation board number DEVB160 is presented as follows. Description The evaluation board shown in Figure 1 is designed to transduce pressure, vacuum or differential pressure into a single-ended, ground referenced voltage that is then input to a voltage-to-frequency converter. It nominally provides a 1 kHz output at zero pressure and 10 kHz at full scale pressure. Zero pressure calibration is made with a trimpot that is located on the lower half of the left side of the board, while the full scale output can be calibrated via another trimpot just above the offset adjust. The board comes with an MPX2100DP sensor installed, but will accommodate any MPX2000 series sensor. One additional modification that may be required is that the gain of the circuit must be increased slightly when using an MPX2010 sensor. Specifically, the resistor R5 must be increased from 7.5 k to 12 k. Circuit Description The following pin description and circuit operation corresponds to the schematic shown in Figure 2. Pin-by-Pin Description B +: Input power is supplied at the B+ terminal of connector CN1. Minimum input voltage is 10 V and maximum is 30 V. Fout: A logic-level (5 V) frequency output is supplied at the OUT terminal (CN1). The nominal signal it provides is 1 kHz at zero Motorola Sensor Device Data Typ PFS Full Scale Output Freescale Semiconductor, Inc... Symbol pressure and 10 kHz at full scale pressure. Zero pressure frequency is adjustable and set with R12. Full-scale frequency is calibrated via R13. This output is designed to be directly connected to a microcontroller timer system input-capture channel. GND: The ground terminal on connector CN1 is intended for use as the power supply return and signal common. Test point terminal TP3 is also connected to ground, for measurement convenience. TP1: Test point 1 is connected to the final frequency output, Fout. TP2: Test point 2 is connected to the +5 V regulator output. It can be used to verify that this supply voltage is within its tolerance. TP3: Test point 3 is the additional ground point mentioned above in the GND description. TP4: Test point 4 is connected to the +8 V regulator output. It can be used to verify that this supply voltage is within its tolerance. P1, P2: Pressure and Vacuum ports P1 and P2 protrude from the sensor on the right side of the board. Pressure port P1 is on the top (marked side of package) and vacuum port P2, if present, is on the bottom. When the board is set up with a dual ported sensor (DP suffix), pressure applied to P1, vacuum applied to P2 or a differential pressure applied between the two all produce the same output voltage per kPa of input. Neither port is labeled. Absolute maximum differential pressure is 700 kPa. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-265 2 3-266 C1 1 F 1 3 on/off S1 3 IN 2 1 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com R4 1.5 k 3 1 4 2 C2 0.1 F TP4 OFFSET R12 200 GROUND OUT U2 MC78L08ACP X1 MPX2100DP D1 MV57124A R8 620 - + 11 U1A MC33274 1 5 6 - + U1B 7 R5 R6 120 7.5 k 2 3 4 R7 820 13 12 10 9 - + - + 8 R9 1 k U1D 14 R10 2 k R11 C4 2 k 0.1 F U1C Freescale Semiconductor, Inc... R13 1 k R3 4.3 k R2 1 k C3 0.01 F C6 0.1 F 1 TP3 + C5 10 F TANTALUM FULL-SCALE VCC Ct Ct VSS 8 7 6 5 OUT GROUND 2 AD654 IN 1 Fout 2 LogCom 3 4 Rt +Vin 3 U4 MC78L05ACP TP1 1 2 3 B+ Fout GND CN1 B+ U5 BS107A R1 240 TP2 AN1316 Freescale Semiconductor, Inc. Figure 2. DEVB160 Frequency Output Sensor Evaluation Board Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1316 The following is a table of the components that are assembled on the DEVB160 Frequency Output Sensor Evaluation Board. Table 2. Parts List Freescale Semiconductor, Inc... Designators Quantity Description Manufacturer Part Number C1 1 1 F Capacitor C2 1 0.1 F Capacitor C3 1 0.01 F Capacitor C4 1 0.1 F Capacitor C5 1 10 F Cap+ C6 1 0.1 F Capacitor CN1 1 .15LS 3 Term PHX Contact 1727023 D1 1 RED LED Quality Tech. MV57124A R1 1 240 resistor R2, R9 2 1 k resistor R3 1 4.3 k resistor R4 1 1.5 k resistor R5 1 7.5 k resistor R6 1 120 resistor R7 1 820 resistor R8 1 620 resistor R10, R11 2 2 k resistor R12 1 200 Trimpot Bourns 3386P-1-201 R13 1 1 k Trimpot Bourns 3386P-1-102 S1 1 SPDT miniature switch NKK SS-12SDP2 TP1 1 YELLOW Testpoint Control Design TP-104-01-04 TP2 1 BLUE Testpoint Control Design TP-104-01-06 TP3 1 BLACK Testpoint Control Design TP-104-01-00 TP4 1 GREEN Testpoint Control Design TP-104-01-05 U1 1 Quad Op Amp Motorola MC33274 U2 1 8 V Regulator Motorola MC78L08ACP U3 1 AD654 Analog Devices AD654 U4 1 5 V Regulator Motorola MC78L05ACP U5 1 Small-Signal FET Motorola BS107A X1 1 Pressure Sensor Motorola MPX2100DP tantalum NOTE: All resistors are 1/4 watt, 5% tolerance values. All capacitors are 50 V rated, 20% tolerance values. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-267 Freescale Semiconductor, Inc... AN1316 Freescale Semiconductor, Inc. Circuit Operation The voltage signal conditioning portion of this circuit is a variation on the classic instrumentation amplifier configuration. It is capable of providing high differential gain and good common-mode rejection with very high input impedance; however, it provides a more user friendly method of performing the offset/bias point adjustment. It uses four op amps and several resistors to amplify and level shift the sensor's output. Most of the amplification is done in U1A which is configured as a differential amplifier. Unwanted current flow through the sensor is prevented by buffer U1B. At zero pressure the differential voltage from pin 2 to pin 4 on the sensor has been precision trimmed to essentially zero volts. The common-mode voltage on each of these nodes is 4 V (one-half the sensor supply voltage). The zero pressure output voltage at pin 1 of U1A is then 4.0 V, since any other voltage would be coupled back to pin 2 via R5 and create a non-zero bias across U1A's differential inputs. This 4.0 V zero pressure DC output voltage is then level translated to the desired zero pressure offset voltage by U1C and U1D. The offset voltage is produced by R4 and adjustment trimpot R12. R7's value is such that the total source impedance into pin 13 is approximately 1 k. The gain is approximately (R5/R6)(1 + R11/R10), which is 125 for the values shown in Figure 2. A gain of 125 is selected to provide a 4 V span for 32 mV of full-scale sensor output (at a sensor supply voltage of 8 V). The resulting .5 V to 4.5 V output from U1C is then converted by the V/F converter to the nominal 1-10 kHz that has been specified. The AD654 V/F converter receives the amplified sensor output at pin 8 of op amp U1C. The full-scale frequency is determined by R3, R13 and C3 according to the following formula: F out (full-scale) + (10V)(R3V)in R13)C3 For best performance, R3 and R13 should be chosen to provide 1 mA of drive current at the full-scale voltage produced at pin 3 of the AD654 (U3). The input stage of the AD654 is an op-amp; thus, it will work to make the voltage at pin 3 of U3 equal to the voltage seen at pin 4 of U3 (pins 3 and 4 are the input terminals of the op amp). Since the amplified sensor output will be 4.5 V at full-scale pressure, R3 + R13 should be approximately equal to 4.5 k to have optimal linearity performance. Once the total resistance from pin 3 of U3 to ground is set, the value of C3 will determine the full-scale frequency output of the V/F. Trimpot R13 should be sized (relative to R3 value) to provide the desired amount of full-scale frequency adjustment. The zero-pressure frequency is adjusted via the offset adjust provided for calibrating the offset voltage of the signal conditioned sensor output. For additional information on using this particular V/F converter, see the applications information provided in the Analog Devices Data Conversion Products Databook. The frequency output has its edge transitions "sped" up by a small-signal FET inverter. This final output is directly compatible with microprocessor timer inputs, as well as any 3-268 other high-speed CMOS logic. The amplifier portion of this circuit has been patented by Motorola Inc. and was introduced on evaluation board DEVB150A. Additional information pertaining to this circuit and the evaluation board DEVB150A is contained in Motorola Application Note AN1313.1 TEST/CALIBRATION PROCEDURE 1. Connect a +12 V supply between B+ and GND terminals on the connector CN1. 2. Connect a frequency counter or scope probe on the Fout terminal of CN1 or on TP1 with the test instrumentation ground clipped to TP3 or GND. 3 . Turn the power switch, S1, to the on position. Power LED, D1, should be illuminated. Verify that the voltage at TP2 and TP4 (relative to GND or TP3) is 5 V and 8 V, respectively. While monitoring the frequency output by whichever means one has chosen, one should see a 50% duty cycle square wave signal. 4. Turn the wiper of the OFFSET adjust trimpot, R12, to the approximate center of the pot. 5. Apply 100 kPa to pressure port P1 of the MPX2100DP (topside port on marked side of the package) sensor, X1. 6. Adjust the FULL-SCALE trimpot, R13, until the output frequency is 10 kHz. If 10 kHz is not within the trim range of the full-scale adjustment trimpot, tweak the offset adjust trimpot to obtain 10 kHz (remember, the offset pot was at an arbitrary midrange setting as per step 4). 7. Apply zero pressure to the pressure port (i.e., both ports at ambient pressure, no differential pressure applied). Adjust OFFSET trimpot so frequency output is 1 kHz. 8. Verify that zero pressure and full-scale pressure (100 kPa) produce 1 and 10 kHz respectively, at Fout and/or TP1. A second iteration of adjustment on both full-scale and offset may be necessary to fine tune the 1 - 10 kHz range. CONCLUSION Transforming conventional analog voltage sensor outputs to frequency has great utility for a variety of applications. Sensing remotely and/or in noisy environments is particularly challenging for low-level (mV) voltage output sensors such as the MPX2000 Series pressure sensors. Converting the MPX2000 sensor output to frequency is relatively easy to accomplish, while providing the noise immunity required for accurate pressure sensing. The evaluation board presented is an excellent tool for either "stand-alone" evaluation of the MPX2000 Series pressure sensors or as a building block for system prototyping which can make use of DEVB160 as a "drop-in" frequency output sensor solution. The output of the DEVB160 circuit is ideally conditioned for interfacing to MCU timer inputs that can measure the sensor frequency signal. REFERENCES 1. Schultz, Warren (Motorola, Inc.), "Sensor Building Block Evaluation Board," Motorola Application Note AN1313. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1318 Interfacing Semiconductor Pressure Sensors to Microcomputers Prepared by: Warren Schultz Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION The most popular silicon pressure sensors are piezoresistive bridges that produce a differential output voltage in response to pressure applied to a thin silicon diaphragm. Output voltage for these sensors is generally 25 to 50 mV full scale. Interface to microcomputers, therefore, generally involves gaining up the relatively small output voltage, performing a differential to single ended conversion, and scaling the analog signal into a range appropriate for analog to digital conversion. Alternately, the analog pressure signal can be converted to a frequency modulated 5 V waveform or 4-20 mA current loop, either of which is relatively immune to noise on long interconnect lines. A variety of circuit techniques that address interface design are presented. Sensing amplifiers, analog to digital conversion, frequency modulation and 4-20 mA current loops are considered. B+ PRESSURE RC1 RP2 RV1 S+ S- RP1 RV2 RC2 RETURN Figure 1. Sensor Equivalent Circuit PRESSURE SENSOR BASICS The essence of piezoresistive pressure sensors is the Wheatstone bridge shown in Figure 1. Bridge resistors RP1, RP2, RV1 and RV2 are arranged on a thin silicon diaphragm such that when pressure is applied RP1 and RP2 increase in value while RV1 and RV2 decrease a similar amount. Pressure on the diaphragm, therefore, unbalances the bridge and produces a differential output signal. One of the fundamental properties of this structure is that the differential output voltage is directly proportional to bias voltage B+. This characteristic implies that the accuracy of the pressure measurement depends directly on the tolerance of the bias supply. It also provides a convenient means for temperature compensation. The bridge resistors are silicon resistors that have positive temperature coefficients. Therefore, when they are placed in series with zero TC temperature compensation resistors RC1 and RC2 the amount of voltage applied to the bridge increases with temperature. This increase in voltage produces an increase in electrical sensitivity which offsets and compensates for the negative temperature coefficient associated with piezoresistance. Since RC1 and RC2 are approximately equal, the output voltage common mode is very nearly fixed at 1/2 B+. In a typical MPX2100 sensor, the bridge resistors are nominally 425 ohms; RC1 and RC2 are nominally 680 ohms. With these values and 10 V applied to B+, a delta R of 1.8 ohms at full scale pressure produces 40 mV of differential output voltage. INSTRUMENTATION AMPLIFIER INTERFACES Instrumentation amplifiers are by far the most common interface circuits that are used with pressure sensors. An example of an inexpensive instrumentation amplifier based interface circuit is shown in Figure 2. It uses an MC33274 quad operational amplifier and several resistors that are configured as a classic instrumentation amplifier with one important exception. In an instrumentation amplifier resistor R3 is normally returned to ground. Returning R3 to ground sets the output voltage for zero differential input to 0 V DC. For microcomputer interface a positive offset voltage on the order of 0.3 to 0.8 V is generally desired. Therefore, R3 is connected to pin 14 of U1D which supplies a buffered offset voltage that is derived from the wiper of R6. This voltage establishes a DC output for zero differential input. The translation is one to one. Within the tolerances of the circuit, whatever voltage appears at the wiper of R6 will also appear as the zero pressure DC offset voltage at the output. With R10 at 240 ohms, gain is set for a nominal value of 125. This provides a 4 V span for 32 mV of full scale sensor output. Setting the offset voltage to .75 V results in a 0.75 V to 4.75 V output that is directly compatible with microprocessor A/D inputs. Over a zero to 50 C temperature range, combined accuracy for an MPX2000 series sensor and this interface is on the order of 10%. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-269 Freescale Semiconductor, Inc. AN1318 B+ U2 3 MC78L08ACP I O 1 G R7 7.5 k 2 C1 1 F C2 0.1 F 5 + 6 - 4 ZERO 7 U1B MC33274 R6 1k 12 13 R4 1k Freescale Semiconductor, Inc... XDCR1 MPX2000 SERIES PRESSURE SENSOR 3 4 2 1 10 9 C3 .001 F R10 240* 2 3 R9 15 k U1A MC33274 1 - + 11 14 U1D MC33274 R3 1 k R8 15 k GND + - U1C MC33274 8 + - R5 R2 1k 1k OUTPUT * NOTE: FOR MPX2010, R10 = 150 OHMS Figure 2. Instrumentation Amplifier Interface For applications requiring greater precision a fully integrated instrument amplifier such as an LTC1100CN8 gives better results. In Figure 3 one of these amplifiers is used to provide a gain of 100, as well as differential to single ended conversion. Zero offset is provided by dividing down the precision reference to 0.5 V and buffering with U2B. This voltage is fed into the LTC1100CN8's ground pin which is equivalent to returning R3 to pin 14 of U1D in Figure 2. An additional non-inverting gain stage consisting of U2A, R1 and R2 is used to scale the sensor's full scale span to 4 V. R2 is also returned to the buffered .5 V to maintain the 0.5 V zero offset that was established in the instrumentation amplifier. Output voltage range is therefore 0.5 to 4.5 V. Both of these instrumentation amplifier circuits do their intended job with a relatively straightforward tradeoff between cost and performance. The circuit of Figure 2 has the usual cumulative tolerance problem that is associated with instrumentation amplifiers that have discrete resistors, but it has a relatively low cost. The integrated instrumentation amplifier in Figure 3 solves this problem with precision trimmed film resistors and also provides superior input offset performance. Component cost, however, is significantly higher. 3-270 SENSOR SPECIFIC INTERFACE AMPLIFIER A low cost interface designed specifically for pressure sensors improves upon the instrumentation amplifier in Figure 2. Shown in Figure 4, it uses one quad op amp and several resistors to amplify and level shift the sensor's output. Most of the amplification is done in U1A which is configured as a differential amplifier. It is isolated from the sensor's positive output by U1B. The purpose of U1B is to prevent feedback current that flows through R5 and R6 from flowing into the sensor. At zero pressure the voltage from pin 2 to pin 4 on the sensor is 0 V. For example, let's say that the common mode voltage on these pins is 4.0 V. The zero pressure output voltage at pin 1 of U1A is then 4.0 V, since any other voltage would be coupled back to pin 2 via R6 and create a non-zero bias across U1A's differential inputs. This 4.0 V zero pressure DC output voltage is then level translated to the desired zero pressure offset voltage (VOFFSET) by U1C and U1D. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1318 B+ U1 1 2 3 4 8 7 6 5 NC NC VIN NC VT OUT GND TRM C3 0.01 F MC1404 U1 C1 1F 6 2 XDCR1 MPX2000 SERIES PRESSURE SENSOR 3 3 C2 0.1 F 1 4 + 5 7 3 - 4 2 1 LTC1100CN8 + - 8 U2A 1 OUTPUT MC34072 Freescale Semiconductor, Inc... 4 R3 19.1 k 1% U2B 5 6 R4 1 k 1% + - R2 10 k 1% 7 R1 6.04 k 1% MC34072 Figure 3. Precision Instrument Amplifier Interface B+ 3 I O U2 MC78L08ACP 1 G 2 C2 0.1 F C1 1 F 3 4 1 + 2 - U1A MC33274 U1C MC33274 10 8 + 9 - R6 7.5 k 3 XDCR1 MPX2000 SERIES PRESSURE 4 SENSOR GND R8 1.5 k 2 1 R1 2 k R5 120* R2 2 k U1B MC33274 7 - 5 + 11 6 R9 200 OUTPUT 12 + 13 - R3 820 14 U1D MC33274 R4 1 k ZERO CAL. * NOTE: FOR MPX2010, R5 = 75 OHMS Figure 4. Sensor Specific Interface Circuit Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-271 Freescale Semiconductor, Inc. AN1318 To see how the level translation works, let's look at the simplified schematic in Figure 5. Again assuming a common mode voltage of 4.0 V, the voltage applied to pin 12 of U1D is 4.0 V, implying that pin 13 is also at 4.0 V. This leaves 4.0 V - VOFFSET across R3, which is 3.5 V if VOFFSET is set to 0.5 V. Since no current flows into pin 13, the same current flows through both R3 and R4. With both of these resistors set to the same value, they have the same voltage drop, implying a 3.5 V drop across R4. Adding the voltages (0.5 + 3.5 + 3.5) yields 7.5 V at pin 14 of U1D. Similarly 4.0 V at pin 10 of U1C implies 4.0 V at pin 9, and the drop across R2 is 7.5 V - 4.0 V = 3.5 V. Again 3.5 V across R2 implies an equal drop across R1, and the voltage at pin 8 is 4.0 V - 3.5 V = .5 V. For this DC output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that R4/R3 = R2/R1. In Figure 4, VOFFSET is produced by R8 and adjustment pot R9. R3's value is adjusted such that the total source impedance into pin 13 is approximately 1 k. B+ 3 4 1 + 2 - U1A MC33274 Freescale Semiconductor, Inc... +8 3 XDCR1 MPX2000 SERIES PRESSURE SENSOR 4 R6 7.5 k 2 1 U1C MC33274 10 8 + 9 - R1 2 k R5 120* R2 2 k U1B MC33274 7 - 5 + 11 6 GND OUTPUT 12 + 13 - R3 1k 14 U1D MC33274 R4 1 k VOFFSET *NOTE: FOR MPX2010, R5 = 75 OHMS Figure 5. Simplified Sensor Specific Interface Gain is approximately (R6/R5)(R1/R2+1), which is 125 for the values shown in Figure 4. A gain of 125 is selected to provide a 4 V span for the 32 mV of full scale sensor output that is obtained with 8 V B+. The resulting 0.5 V to 4.5 V output from U1C is preferable to the 0.75 to 4.75 V range developed by the instrument amplifier configuration in Figure 2. It also uses fewer parts. This circuit does not have the instrument amplifier's propensity for oscillation and therefore does not require compensation capacitor C3 that is shown in Figure 2. It also requires one less resistor, which in addition to reducing component count also reduces accumulated tolerances due to resistor variations. This circuit as well as the instrumentation amplifier interfaces in Figures 2 and 3 is designed for direct connection to a 3-272 microcomputer A/D input. Using the MC68HC11 as an example, the interface circuit output is connected to any of the E ports, such as port E0 as shown in Figure 6. To get maximum accuracy from the A/D conversion, VREFH is tied to 4.85 V and VREFL is tied to 0.30 V by dividing down a 5 V reference with 1% resistors. SINGLE SLOPE A/D CONVERTER The 8 bit A/D converters that are commonly available on chip in microcomputers are usually well suited to pressure sensing applications. In applications that require more than 8 bits, the circuit in Figure 7 extends resolution to 11 bits with an external analog-to-digital converter. It also provides an interface to digital systems that do not have an internal A/D function. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. +5 V B+ 15.0 OHMS 1% X4.85 V VS MPX2000 SERIES PRESSURE SENSOR 453 OHMS 1% RC1 X.302 V RV1 RP2 S+ S- RV2 VREFL MC68HC11 B+ + 0 INTERFACE OUTPUT AMPLIFIER RP1 VREFH 30.1 OHMS 1% BIAS 1 2 -- 3 4 GND Freescale Semiconductor, Inc... AN1318 PORT E 5 RC2 6 7 GND VSS RETURN Figure 6. Application Example Beginning with the ramp generator, a timing ramp is generated with current source U5 and capacitor C3. Initialization is provided by Q1 which sets the voltage on C3 at approximately ground. With the values shown, 470 A flowing into 0.47 F provide approximately a 5 msec ramp time from zero to 5 V. Assuming zero pressure on the sensor, inputs to both comparators U2A and U2B are at the same voltage. Therefore, as the ramp voltage sweeps from zero to 5 V, both PA0 and PA1 will go low at the same time when the ramp voltage exceeds the common mode voltage. The processor counts the number of clock cycles between the time that PA0 and PA1 go low, reading zero for zero pressure. In this circuit, U4A and U4B form the front end of an instrument amplifier. They differentially amplify the sensor's output. The resulting amplified differential signal is then sampled and held in U1 and U3. The sample and hold function is performed in order to keep input data constant during the conversion process. The stabilized signals coming out of U1 and U3 feed a higher output voltage to U2A than U2B, assuming that pressure is applied to the sensor. Therefore, the ramp will trip U2B before U2A is tripped, creating a time difference between PA0 going low and PA1 going low. The processor reads the number of clock cycles between these two events. This number is then linearly scaled with software to represent the amplified output voltage, accomplishing the analog to digital conversion. When the ramp reaches the reference voltage established by R9 and R10, comparator U2C is tripped, and a reset command is generated. To accomplish reset, Q1 is turned on Motorola Sensor Device Data with an output from PA7, and the sample and hold circuits are delatched with an output from PB1. Resolution is limited by clock frequency and ramp linearity. With the ramp generator shown in Figure 7 and a clock frequency of 2 MHz; resolution is 11 bits. From a software point of view, the A/D conversion consists of latching the sample and hold, reading the value of the microcomputer's free running counter, turning off Q1, and waiting for the three comparator outputs to change state from logic 1 to logic 0. The analog input voltage is determined by counting, in 0.5 sec steps, the number of clock cycles between PA0 and PA1 going low. LONG DISTANCE INTERFACES In applications where there is a significant distance between the sensor and microcomputer, two types of interfaces are typically used. They are frequency output and 4-20 mA loops. In the frequency output topology, pressure is converted into a zero to 5 V digital signal whose frequency varies linearly with pressure. A minimum frequency corresponds to zero pressure and above this, frequency output is determined by a Hz/unit pressure scaling factor. If minimizing the number of wires to a remote sensor is the most important design consideration, 4-20 mA current loops are the topology of choice. These loops utilize power and ground as the 4-20 mA signal line and therefore require only two wires to the sensor. In this topology 4 mA of total current drain from the sensor corresponds to zero pressure, and 20 mA to full scale. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-273 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com +5 +10 2 1 3 4 NOTE: UNLESS OTHERWISE SPECIFIED ALL RESISTORS ARE 1% METAL FILM XDCR1 MPX2000 SERIES PRESSURE SENSOR U5 LM334Z-3 1 C2 22 pF C1 22 pF R2 402 k U4A MC33078 4 1.5 k 5% R6 11 U4B MC33078 7 R3 402 k 6 5 - R5 120* 2 - 3 R4 147 1N914 D1 7 6 4 8 3 7 1 6 4 +8.5 -8.5 8 3 1 R8 22 k 5% C4 0.01 F POLYPROP LF398A 5 U3 R7 22 k 5% C5 0.01 F POLYPROP LF398A 5 U1 +8.5 -8.5 C3 0.47 F 10 11 7 6 4 5 9 8 - + 4.7 5% - + 2 1 13 LM139A U2D LM139A U2B 2N7000 Q1 14 LM139A U2A R5 LM139A U2C Freescale Semiconductor, Inc... + - + + - 3-274 + C7 0.1 F +5 R10 9.09 k R9 1k PA0 PB1 PA1 U7 MC68HC11E9FN PA7 PA2 AN1318 Freescale Semiconductor, Inc. Figure 7. Single Slope A/D Converter Motorola Sensor Device Data Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com C1 1 F G I 2 3 O 200 R5 1.5 k 4 3 1 2 XDCR1 MPX2000 SERIES PRESSURE SENSOR ZERO CAL. R3 1 U1 MC78L08ACP * NOTE: FOR MPX2010, R8 = 75 OHMS GND B+ R4 7.5 k 11 U2B MC33274 6 - 7 5 + R8 120* 4 U2A MC33274 + 2 - 3 R2 820 10 - 9 + U2C MC33274 R1 1 k 8 R7 2 k U2D 12 MC33274 14 13 +- R6 2 k C2 0.1 F RT VIN + V S 8 R12 1k FULL SCALE CAL. R11 4.3 k 3 4 U3 AD654 5 - V S Freescale Semiconductor, Inc... 0 5V C T 6 C O M 2 FOUT C T 7 1 2 G 3 NOMINAL OUTPUT: 1 kHz @ ZERO PRESSURE 10 kHz @ FULL SCALE 0.01 F C3 R9 1k I O 1 R10 240 OUTPUT C4 0.1 F Q1 BS107A U4 MC78L05ACP Freescale Semiconductor, Inc. AN1318 Figure 8. Frequency Output Pressure Sensor 3-275 Freescale Semiconductor, Inc. AN1318 a twisted pair line is relatively easy. Where very long distances are involved, the primary disadvantage is that 3 wires (VCC, ground and an output line) are routed to the sensor. A 4-20 mA loop reduces the number of wires to two. Its output is embedded in the VCC and ground lines as an active current source. A straightforward way to apply this technique to pressure sensing is shown in Figure 9. In this figure an MPX7000 series high impedance pressure sensor is mated to an XTR101 4-20 mA two-wire transmitter. It is set up to pull 4 mA from its power line at zero pressure and 20 mA at full scale. At the receiving end a 240 ohm resistor referenced to signal ground will provide a 0.96 to 4.8 V signal that is suitable for microcomputer A/D inputs. A relatively straightforward circuit for converting pressure to frequency is shown in Figure 8. It consists of three basic parts. The interface amplifier is the same circuit that was described in Figure 4. Its 0.5 to 4.5 V output is fed directly into an AD654 voltage-to-frequency converter. On the AD654, C3 sets nominal output frequency. Zero pressure output is calibrated to 1 kHz by adjusting the zero pressure input voltage with R3. Full scale adjustments are made with R12 which sets the full scale frequency to 10 kHz. The output of the AD654 is then fed into a buffer consisting of Q1 and R10. The buffer is used to clean up the edges and level translate the output to 5 V. Advantages of this approach are that the frequency output is easily read by a microcomputer's timer and transmission over Freescale Semiconductor, Inc... 2 mA 4-20 mA OUTPUT XDCR1 MPX7000 SERIES SENSOR 3 2 R3 30 5 6 1 4 4 R5 100 3 1 0 1 1 D1 1N4002 Q1 MPSA06 C1 0.01 F + U1 XTR101 - 12 + R1 750 1/2 W 8 24 V .96 - 4.8 V PLOOP 240 1 2 1 7 1 9 4 3 D2 1N4565A 6.4 V @ .5 mA SPAN - R6 100 k R2 1k R4 1M RETURN OFFSET Figure 9. 4-20 mA Pressure Transducer Bias for the sensor is provided by two 1 mA current sources (pins 10 and 11) that are tied in parallel and run into a 1N4565A 6.4 V temperature compensated zener reference. The sensor's differential output is fed directly into XTR101's inverting and non-inverting inputs. Zero pressure offset is calibrated to 4 mA with R6. Biased with 6.4 V, the sensor's full scale output is 24.8 mV. Given this input R3 + R5 nominally total 64 ohms to produce the 16 mA span required for 20 mA full scale. Calibration is set with R5. The XTR101 requires that the differential input voltage at pins 3-276 3 and 4 has a common mode voltage between 4 and 6 V. The sensor's common mode voltage is one half its supply voltage or 3.2 V. R2 boosts this common mode voltage by 1 k S 2 mA or 2 V, establishing a common mode voltage for the transmitter's input of 5.2 V. To allow operation over a 12 to 40 V range, dissipation is off-loaded from the IC by boosting the output with Q1 and R1. D1 is also included for protection. It prohibits reverse polarity from causing damage. Advantages of this topology include simplicity and, of course, the two wire interface. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data +5 Motorola Sensor Device Data J1 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com J2 R2 10 k R3 10 k 3 C1 22 pF XDCR1 MPX5100 C2 22 pF U2 R1 10 M MC34064P-5 4.7 k R4 2 1 Y1 4 MHz OSC2 OSC1 PD6 PD7 RESET PD5 IRQ VPP6 PD1 PD2 PD3 PD4 VDD PD0 TCAP2 TCAP1 D/A R6 15 % VSS U1 RDI TDO VRL MC68HC705B5FN VRH R5 453 % PA0 PA2 PA1 PA7 PA6 PA5 PA4 PA3 PB2 PB1 PB7 PB6 PB5 PB4 PB3 PC0 PC2 PC1 PC7 PC6 PC5 PC4 PC3 R7 30.1 % Freescale Semiconductor, Inc... 40 22 23 17 18 19 20 21 16 26 27 13 14 15 24 25 12 31 32 9 10 11 29 30 1 2 3 4 5 6 7 28 33 34 35 36 37 38 39 8 LIQUID CRYSTAL DISPLAY IEEE LCD 5657 OR EQUIVALENT Freescale Semiconductor, Inc. AN1318 Figure 10. MPX5100 LCD Pressure Gauge 3-277 AN1318 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... DIRECT INTERFACE WITH INTEGRATED SENSORS The simplest interface is achieved with an integrated sensor and a microcomputer that has an on-chip A/D converter. Figure 10 shows an LCD pressure gauge that is made with an MPX5100 integrated sensor and MC68HC05 microcomputer. Although the total schematic is reasonably complicated, the interface between the sensor and the micro is a single wire. The MPX5100 has an internal amplifier that outputs a 0.5 to 4.5 V signal that inputs directly to A/D port PD5 on the HC05. The software in this system is written such that the processor assumes zero pressure at power up, reads the sensor's output voltage, and stores this value as zero pressure offset. Full scale span is adjustable with jumpers J1 and J2. For this particular system the software is written such that with J1 out and J2 in, span is decreased by 1.5%. Similarly with J1 in and J2 out, span is increased by 1.5%. Given the 2.5% full scale spec on the sensor, these jumpers allow calibration to 1% without the use of pots. MIX AND MATCH The circuits that have been described so far are intended to be used as functional blocks. They may be combined in a variety of ways to meet the particular needs of an application. For example, the Frequency Output Pressure Sensor in Figure 8 uses the sensor interface circuit described in Figure 4 to provide an input to the voltage-to-frequency converter. Alternately, an MPX5100 could be directly connected to pin 4 of the AD654 or the output of Figure 3's Precision Instrumentation Amplifier Interface could by substituted in the same way. Similarly, the Pressure Gauge described in Figure 10 could be constructed with any of the interfaces that have been described. 3-278 CONCLUSION The circuits that have been shown here are intended to make interfacing semiconductor pressure sensors to digital systems easier. They provide cost effective and relatively simple ways of interfacing sensors to microcomputers. The seven different circuits contain many tradeoffs that can be matched to the needs of individual applications. When considering these tradeoffs it is important to throw software into the equation. Techniques such as automatic zero pressure calibration can allow one of the inexpensive analog interfaces to provide performance that could otherwise only be obtained with a more costly precision interface. REFERENCES 1. Baum, Jeff, "Frequency Output Conversion for MPX2000 Series Pressure Sensors," Motorola Application Note AN1316/D. 2. Lucas, William, "An Evaluation System for Direct Interface of the MPX5100 Pressure Sensor with a Microprocessor," Motorola Application Note AN1305. 3. Lucas, William, "An Evaluation System for Interfacing the MPX2000 Series Pressure Sensors to a Microprocessor," Motorola Application Note AN1315. 4. Schultz, Warren, "Compensated Sensor Bar Graph Pressure Gauge," Motorola Application Note AN1309. 5. Schultz, Warren, "Interfaced Sensor Evaluation Board," Motorola Application Note AN1312. 6. Schultz, Warren, "Sensor Building Block Evaluation Board," Motorola Application Note AN1313. 7. Williams, Denise, "A Simple 4-20 mA Pressure Transducer Evaluation Board," Motorola Application Note AN1303. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Applying Semiconductor Sensors to Bar Graph Pressure Gauges AN1322 Prepared by: Warren Schultz Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Bar Graph displays are noted for their ability to very quickly convey a relative sense of how much of something is present. They are particularly useful in process monitoring applications where quick communication of a relative value is more important than providing specific data. Designing bar graph pressure gauges based upon semiconductor pressure sensors is relatively straightforward. The sensors can be interfaced to bar graph display drive IC's, microcomputers and MC33161 voltage monitors. Design examples for all three types are included. BAR GRAPH DISPLAY DRIVER Interfacing semiconductor pressure sensors to a bar graph display IC such as an LM3914 is very similar to microcomputer interface. The same 0.5 to 4.5 V analog signal that a microcomputer's A/D converter wants to see is also quite suitable for driving an LM3914. In Figure 1, this interface is provided by dual op amp U2 and several resistors. The op amp interface amplifies and level shifts the sensor's output. To see how this amplifier works, simplify it by grounding the output of voltage divider R3, R5. If the common mode voltage at pins 2 and 4 of the sensor is 4.0 V, then pin 2 of U2A and pin 6 of U2B are also at 4.0 V. This puts 4.0 V across R6. Assuming that the current in R4 is equal to the current in R6, 323 A * 100 ohms produces a 32 mV drop across R4 which adds to the 4.0 V at pin 2. The output voltage at pin 1 of U2A is, therefore, 4.032 V. This puts 4.032 - 4.0 V across R2, producing 43 A. The same current flowing through R1 again produces a voltage drop of 4.0 V, which sets the output at zero. Substituting a divider output greater than zero into this calculation reveals that the zero pressure output voltage is equal to the output voltage of divider R3, R5. For this DC output voltage to be independent of the sensor's common mode voltage, it is necessary to satisfy the condition that R1/R2 = R6/R4. Gain can be determined by assuming a differential output at the sensor and going through the same calculation. To do this assume 100 mV of differential output, which puts pin 2 of U2A at 3.95 V, and pin 6 of U2B at 4.05 V. Therefore, 3.95 V is applied to R6, generating 319 A. This current flowing through R4 produces 31.9 mV, placing pin 1 of U2A at 3950 mV + 31.9 mV = 3982 mV. The voltage across R2 is then 4050 mV - 3982 mV = 68 mV, which produces a current of 91 A that flows into R1. The output voltage is then 4.05 V + (91 A * 93.1k) = 12.5 V. Dividing 12.5 V by the 100 mV input yields a gain of 125, which provides a 4.0 V span for 32 mV of full scale sensor output. Setting divider R3, R5 at 0.5 V results in a 0.5 V to 4.5 V output that is easily tied to an LM3914. The block diagram that appears in Figure 2 shows the LM3914's internal architecture. Since the lower resistor in the input comparator chain is pinned out at RLO, it is a simple matter to tie this pin to a voltage that is approximately equal to the interface circuit's 0.5 V zero pressure output voltage. Returning to Figure 1, this is accomplished by using the zero pressure offset voltage that is generated at the output of divider R3, R5. Again looking at Figure 1, full scale is set by adjusting the upper comparator's reference voltage to match the sensor's output at full pressure. An internal regulator on the LM3914 sets this voltage with the aid of resistors R7, R9, and adjustment pot R8. Eight volt regulated power is supplied by an MC78L08. The LED's are powered directly from LM3914 outputs, which are set up as current sources. Output current to each LED is approximately 10 times the reference current that flows from pin 7 through R7, R8, and R9 to ground. In this design it is nominally (4.5 V/4.9 k)10 = 9.2 mA. Over a zero to 50C temperature range combined accuracy for the sensor, interface, and driver IC are 10%. Given a 10 segment display total accuracy for the bar graph readout is approximately (10 kPa +10%). This circuit can be simplified by substituting an MPX5100 integrated sensor for the MPX2100 and the op amp interface. The resulting schematic is shown in Figure 3. In this case zero reference for the bar graph is provided by dividing down the 5 V regulator with R4, R1 and adjustment pot R6. The voltage at the wiper of R6 is adjusted to match the sensor's zero pressure offset voltage. It is connected to RLO to zero the bar graph. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-279 Freescale Semiconductor, Inc. AN1322 B+ D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 C2 1 F D1-D10 MV57164 BAR GRAPH C2 0.1F U3 3 U1 I MC78L08ACP O 1 5 G Freescale Semiconductor, Inc... XDCR1 MPX2000 SERIES 1 SENSOR 3 2 6 2 4 GND 1 2 3 4 5 6 7 8 9 R3 1.5 k 1% 8 + - 7 U2B R1 93.1 k 1% MC3327 2 C3 0.001 F R7 1.2 k R6 3 + 2 - 18 17 16 15 14 13 12 11 10 LM3914N R2 750 1% R9 2.7 k 4 12.4 k 1% R5 100 1% FOR MPX2010 SENSORS: R1 = 150 k R4 = 61.9 OHMS R4 Figure 1. Compensated Sensor Bar Graph Pressure Gauge 100 1% COMPARATOR LM391 1 of 10 10 - 4 + 6 REF OUT 1k - + 11 1k - + 12 1k - + 13 1k - + 14 - + 15 +- 16 REFERENCE 1 k 7 + VOLTAGE SOURCE 1.25 V 1k THIS LOAD DETERMINES LED BRIGHTNESS LED LED LED LED LED LED LED LED LED R8 1k U2A MC33272 RHI LED GND B+ RLO SIG RHI REF ADJ MOD - LED V+ 17 REF ADJ 8 1k - + 1k - + 1k - + FROM PIN 11 18 V+ RLO 3 1k 4 - 5 20 k SIG IN BUFFER + V+ 1 9 MODE SELECT AMPLIFIER 2 V- CONTROLS TYPE OF DISPLAY, BAR OR SINGLE LED Figure 2. LM3914 Block Diagram 3-280 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. +12 V D1 D2 D3 D4 AN1322 D5 D6 D7 D8 D9 D10 C2 1 F U1 1 2 3 4 5 6 7 8 9 C1 0.1 F U3 3 I 1 O MC78L05ACP Freescale Semiconductor, Inc... G 3 2 R4 1.3 k GND 1 U2 MPX5100 R2 1.2 k 2 R5 1k ZERO CAL. R6 100 LED GND B+ RLO SIG RHI REF ADJ MOD LED LED LED LED LED LED LED LED LED 18 17 16 15 14 13 12 11 10 LM3914 FULL SCALE CAL. R3 2.7 k R1 100 Figure 3. MPX5100 Bar Graph Pressure Gauge +5 D/A VRH TCAP1 TCAP2 VDD PD0 PD1 PD2 PD3 PD4 VPP6 IRQ PD5 3 D2 MV53214A MV54124A D3 D4 D5 VRL MV54124A MV54124A MV57124A PC0 I1 MDC4510A PC1 1 XDCR1 MPX5100 I2 MDC4510A U1 MC68HC705B5FN 2 R3 4.7 k D1 PC2 I3 MDC4510A U2 R2 10 k MC34064P-5 R1 10 k J2 PC3 I4 MDC4510A PD6 PD7 C1 22 pF J1 RESET Y1 4 MHz OSC1 PC4 R4 10 M C2 22 pF Motorola Sensor Device Data OSC2 VSS I5 MDC4510A RDI TDO Figure 4. Microcomputer Bar Graph Pressure Gauge www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-281 Freescale Semiconductor, Inc. AN1322 B+ 1 I2 MDC4010A 1 I3 MDC4010A D6 MV53124A LOW D4 2 MV54124A 0k D5 MV57124A HIGH C1 0.1 F 2 C2 0.1 F U1 3 I O 1 XDCR1 MPX2000 SERIES SENSOR G MC78L08ACP 2 3 GND 5 8 + 6 - R7 7.5 k 7 D1 1N914 Freescale Semiconductor, Inc... R1 93.1 k 1% R3 6.65 k 1% R5 1.33 k 1% 4 R6 11.3 k 1% U2A 3 MC33272 + 1 2 - 4 R2 750 1% U3 R8 10 k LOW R9 10 k HI R4 100 1% R10 2.7 k 1 7 2 D2 1N914 C3 0.001 F 1 I1 MDC4510A 3 U2B MC33272 2 1 R11 2.7 k VREF 1 2 3 4 REF IN1 IN2 GND VCC MODE OUT1 OUT2 8 7 6 5 MC33161 Figure 5. An Inexpensive 3-Segment Processor Monitor 2.54 V REFERENCE VCC 8 MODE SELECT - + OUT1 6 2.8 V 2 INPUT1 + - 1.27 V - + OUT2 5 0.6 V 3 INPUT2 + - 1.27 V GND 4 3-282 Figure 6. MC33161 Block Diagram www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... MICROCOMPUTER BAR GRAPH Microcomputers with internal A/D converters such as an MC68HC05B5 lend themselves to easily creating bar graphs. Using the A/D converter to measure the sensor's analog output voltage and output ports to individually switch LED's makes a relatively straightforward pressure gauge. This type of design is facilitated by a new MDC4510A gated current sink. The MDC4510A takes one of the processor's logic outputs and switches 10 mA to an LED. One advantage of this approach is that it is very flexible regarding the number of segments that are used, and has the availability through software to independently adjust scaling factors for each segment. This approach is particularly useful for process monitoring in systems where a microprocessor is already in place. Figure 4 shows a direct connection from an MPX5100 sensor to the microcomputer. Similar to the previous example, an MPX2000 series sensor with the op amp interface that is shown in Figure 1 can be substituted for the MPX5100. In this case the op amp interface's output at pin 7 ties to port PD5, and its supply needs to come from a source greater than 6.5 V. PROCESS MONITOR For applications where an inexpensive HIGH-LOW-OK process monitor is required, the circuit in Figure 5 does a good job. It uses an MC33161 Universal Voltage Monitor and the same analog interface previously described to indicate high, low or in-range pressure. A block diagram of the MC33161 is illustrated in Figure 6. By tying pin 1 to pin 7 it is set up as a window detector. Whenever input 1 exceeds 1.27 V, two logic ones are placed at the inputs of its exclusive OR gate, turning off output 1. Therefore this output is on unless the lower threshold is exceeded. When 1.27 V is exceeded on input 2, just the opposite occurs. A single logic one appears at its exclusive OR gate, turning on output 2. These two outputs drive LED's through MDC4010A 10 mA current sources to indicate low pressure and high pressure. Returning to Figure 5, an in-range indication is developed by turning on current source I1 whenever both the high and low outputs are off. This function is accomplished with a discrete gate made from D1, D2 and R7. Its output feeds the Motorola Sensor Device Data AN1322 input of switched current source I1, turning it on with R7 when neither D1 nor D2 is forward biased. Thresholds are set independently with R8 and R9. They sample the same 4.0 V full scale span that is used in the other examples. However, zero pressure offset is targeted for 1.3 V. This voltage was chosen to approximate the 1.27 V reference at both inputs, which avoids throwing away the sensor's analog output signal to overcome the MC33161's input threshold. In addition, R10 and R11 are selected such that at full scale output, ie., 5.3 V on pin 7, the low side of the pots is nominally at 1.1 V. This keeps the minimum input just below the comparator thresholds of 1.27 V, and maximizes the resolution available from adjustment pots R8 and R9. When level adjustment is not desired, R8 - R11 can be replaced by a simpler string of three fixed resistors. CONCLUSION The circuits that have been shown here are intended to make simple, practical and cost effective bar graph pressure gauges. Their application involves a variety of trade-offs that can be matched to the needs of individual applications. In general, the most important trade-offs are the number of segments required and processor utilization. If the system in which the bar graph is used already has a microprocessor with unused A/D channels and I/O ports, tying MDC4510A current sources to the unused output ports is a very cost effective solution. On a stand-alone basis, the MC33161 based process monitor is the most cost effective where only 2 or 3 segments are required. Applications that require a larger number of segments are generally best served by one of the circuits that uses a dedicated bar graph display. REFERENCES 1. Alberkrack, Jade, & Barrow, Stephen; "Power Supply Monitor IC Fills Voltage Sensing Roles," Power Conversion & Intelligent Motion, October 1991. 2. Lucas, William, "An Evaluation System for Direct Interface of the MPX5100 Pressure Sensor with a Microprocessor," Motorola Application Note AN1305. 3. Schultz, Warren, "Integrated Sensor Simplifies Bar Graph Pressure Gauge," Motorola Application Note AN1304. 4. Schultz, Warren, "Compensated Sensor Bar Graph Pressure Gauge," Motorola Application Note AN1309. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-283 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1325 Amplifiers for Semiconductor Pressure Sensors Prepared by: Warren Schultz Discrete Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION Amplifiers for interfacing Semiconductor Pressure Sensors to electronic systems have historically been based upon classic instrumentation amplifier designs. Instrumentation amplifiers have been widely used because they are well understood standard building blocks that also work reasonably well. For the specific job of interfacing Semiconductor Pressure Sensors to today's mostly digital systems, other circuits can do a better job. This application note presents an evolution of amplifier design that begins with a classic instrumentation amplifier and ends with a simpler circuit that is better suited to sensor interface. INTERFACE AMPLIFIER REQUIREMENTS Design requirements for interface amplifiers are determined by the sensor's output characteristics, and the zero to 5 V input range that is acceptable to microcomputer A/D converters. Since the sensor's full scale output is typically tens of millivolts, the most obvious requirement is gain. Gains from 100 to 250 are generally needed, depending upon bias voltage applied to the sensor and maximum pressure to be measured. A differential to single-ended conversion is also required in order to translate the sensor's differential output into a single ended analog signal. In addition, level shifting is necessary to convert the sensor's 1/2 B+ common mode voltage to an appropriate DC level. For microcomputer A/D inputs, generally that level is from 0.3 - 1.0 V. Typical design targets are 0.5 V at zero pressure and enough gain to produce 4.5 V at full scale. The 0.5 V zero pressure offset allows for output saturation voltage in op amps operated with a single supply (VEE = 0). At the other end, 4.5 V full scale keeps the output within an A/D converter's 5 V range with a comfortable margin for component tolerances. The resulting 0.5 to 4.5 V single-ended analog signal is also quite suitable for a variety of other applications such as bar graph pressure gauges and process monitors. CLASSIC INSTRUMENTATION AMPLIFIER A classic instrumentation amplifier is shown in Figure 1. This circuit provides the gain, level shifting and differential to single-ended conversion that are required for sensor interface. It does not, however, provide for single supply operation with a zero pressure offset voltage in the desired range. VCC 5 4 7 + 6 - U1B MC33274 + R4 1k R31k R8 15 k 10 + 9 - C3 0.001 F R10 240* OUTPUT R9 15 k U1A MC33274 - 8 U1C MC33274 2 - 3 + 1 R5 1k R2 1k * NOTE: FOR MPX2020 R10 = 150 OHMS 11 VEE Figure 1. Classic Instrumentation Amplifier REV 2 3-284 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. B+ U2 MC78L08ACP 3 I O G 1 C2 0.1 F 2 C1 1 F R7 7.5 k R6 ZERO 5 + 4 7 6 - U1B MC33274 R8 15 k GND 3 Freescale Semiconductor, Inc... AN1325 XDCR1 MPX2000 SERIES PRESSURE SENSOR 2 4 1 R4 1k 0.001 F C3 R10 240* 1k 12 + 13 - 14 U1D MC33274 R3 1 k U1C MC33274 10 8 + 9 - R9 R5 R2 15 k U1A 2 MC33274 - 1 3 + 11 1k 1k OUTPUT * NOTE: FOR MPX2010 R10 = 150 OHMS Figure 2. Instrumentation Amplifier Interface To provide the desired DC offset, a slight modification is made in Figure 2. R3 is connected to pin 14 of U1D, which supplies a buffered offset voltage that is derived from the wiper of R6. This voltage establishes a DC output for zero differential input. The translation is one to one. Whatever voltage appears at the wiper of R6 will, within component tolerances, appear as the zero pressure DC offset voltage at the output. With R10 at 240 gain is set for a nominal value of 125, providing a 4 V span for 32 mV of full scale sensor output. Setting the offset voltage to 0.75 V, results in a 0.75 V to 4.75 V output that is directly compatible with microprocessor A/D inputs. This circuit works reasonably well, but has several notable limitations when made with discrete components. First, it has a relatively large number of resistors that have to be well matched. Failure to match these resistors degrades common mode rejection and initial tolerance on zero pressure offset voltage. It also has two amplifiers in one gain loop, which makes stability more of an issue than it is in the following two alternatives. This circuit also has more of a limitation on zero pressure offset voltage than the other two. The minimum output voltage of U1D restricts the minimum zero pressure offset voltage that can be accommodated, given component tolerances. The result is a 0.75 V zero pressure offset voltage, compared to 0.5 V for each of the following two circuits. Motorola Sensor Device Data SENSOR SPECIFIC AMPLIFIER The limitations associated with classic instrumentation amplifiers suggest that alternate approaches to sensor interface design are worth looking at. One such approach is shown in Figure 3. It uses one quad op amp and several resistors to amplify and level shift the sensor's output. Most of the amplification is done in U1A, which is configured as a differential amplifier. It is isolated from the sensor's minus output by U1B. The purpose of U1B is to prevent feedback current that flows through R5 and R6 from flowing into the sensor. At zero pressure the voltage from pin 2 to pin 4 on the sensor is zero V. For example, assume that the common mode voltage is 4.0 V. The zero pressure output voltage at pin 1 of U1A is then 4.0 V, since any other voltage would be coupled back to pin 2 via R6 and create a non zero bias across U1A's differential inputs. This 4.0 V zero pressure DC output voltage is then level translated to the desired zero pressure offset voltage by U1C and U1D. To see how the level translation works, assume that the wiper of R9 is at ground. With 4.0 V at pin 12, pin 13 is also at 4.0 V. This leaves 4.0 V across (R3+R9), which total essentially 1 k. Since no current flows into pin 13, the same current flows through R4, producing approximately 4.0 V across R4, as well. Adding the voltages (4.0 + 4.0) yields 8.0 V at pin 14. Similarly 4.0 V at pin 10 implies 4.0 V at pin 9, and the drop across R2 is 8.0 V - 4.0 = 4.0 V. Again 4.0 V across R2 implies an equal drop www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-285 Freescale Semiconductor, Inc. AN1325 B+ U2 3 MC78L08ACP I 1 O G 2 C1 1 F TP2 +8 V 3 XDCR1 MPX2000 SERIES PRESSURE SENSOR GND R8 1.5 k + 2 - 3 4 Freescale Semiconductor, Inc... R9 200 2 1 4 C2 0.1 F 1 U1A MC33274 10 + 9 - R6 7.5 k R5 120* U1B 6 MC33274 7 - 5 + 11 U1C MC33274 8 OUT R1 2 k R2 2 k 12 R3 820 + 13 - 14 U1D MC33274 R4 1 k ZERO CAL. * NOTE: FOR MPX2010 R5 = 75 OHMS Figure 3. Sensor Specific Amplifier across R1, and the voltage at pin 8 is 4.0 V - 4.0 V = 0 V. In practice, the output of U1C will not go all the way to ground, and the voltage injected by R8 at the wiper of R9 is approximately translated into a DC offset. Gain is approximately equal to R6/R5(R1/R2+1), which predicts 125 for the values shown in Figure 3. A more exact calculation can be performed by doing a nodal analysis, which yields 127. Cascading the gains of U1A and U1C using standard op amp gain equations does not give an exact result, because the sensor's negative going differential signal at pin 4 subtracts from the DC level that is amplified by U1C. Setting offset to 0.5 V results in an analog zero to full scale range of 0.5 to 4.5 V. For this DC output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that R1/R2 = (R3+R9)/R4. This approach to interface amplifier design is an improvement over the classic instrument amplifier in that it uses fewer resistors, is inherently more stable, and provides a zero pressure output voltage that can be targeted at .5 V. It has the same tolerance problem from matching discrete resistors that is associated with classic instrument amplifiers. SENSOR MINI AMP Further improvements can be made with the circuit that is shown in Figure 4. It uses one dual op amp and several resistors to amplify and level shift the sensor's output. To see how this amplifier works, let's simplify it by grounding the output of voltage divider R3, R5 and assuming that the divider impedance is added to R6, such that R6 = 12.4 k. If the common mode voltage at pins 2 and 4 of the sensor is 4.0 V, 3-286 then pin 2 of U2A and pin 6 of U2B are also at 4.0 V. This puts 4.0 V across R6, producing 323 A. Assuming that the current in R4 is equal to the current in R6, 323 A * 100 produces a 32 mV drop across R4 which adds to the 4.0 V at pin 2. The output voltage at pin 1 of U2A is, therefore, 4.032 V. This puts 4.032 - 4.0 V across R2, producing 43 A. The same current flowing through R1 again produces a voltage drop of 4.0 V, which sets the output at zero. Substituting a divider output greater than zero into this calculation reveals that the zero pressure output voltage is equal to the output voltage of divider R3, R5. For this DC output voltage to be independent of the sensor's common mode voltage it is necessary to satisfy the condition that R1/R2 = R6/R4, where R6 includes the divider impedance. Gain can be determined by assuming a differential output at the sensor and going through the same calculation. To do this assume 100 mV of differential output, which puts pin 2 of U2A at 3.95 V, and pin 6 of U2B at 4.05 V. Therefore, 3.95 V is applied to R6, generating 319 uA. This current flowing through R4 produces 31.9 mV, placing pin 1 of U2A at 3950 mV + 31.9 mV = 3982 mV. The voltage across R2 is then 4050 mV - 3982 mV = 68 mV, which produces a current of 91 A that flows into R1. The output voltage is then 4.05 V + (91 A * 93.1 k) = 12.5 V. Dividing 12.5 V by the 100 mV input yields a gain of 125, which provides a 4 V span for 32 mV of full scale sensor output. Setting divider R3, R5 at 0.5 V results in a 0.5 V to 4.5 V output that is comparable to the other two circuits. This circuit performs the same function as the other two with significantly fewer components and lower cost. In most cases it is the optimum choice for a low cost interface amplifier. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1325 B+ C1 0.2 F U1 3 MC78L08ACP I 1 O G C2 2 0.2 F 5 + 6 - 3 2 4 1 XDCR1 MPX2000 SERIES SENSOR R3 39.2 k 1% R7 TRIM U1B MC33272 1 + 2 - 4 3 Freescale Semiconductor, Inc... 7 OUT U2B MC33272 R1 93.1 k 1% C2 0.001 F GND R6 11 k 1% R5 1.33 k 1% 8 NOTES: R7 IS NOMINALLY 39.2 k AND SELECTED FOR ZERO PRESSURE VOUT = 0.5 V FOR MPX2010 SENSORS R1 = 150 k AND R4 = 61.9 OHMS R2 750 1% R4 100 1% Figure 4. Sensor Mini Amp PERFORMANCE Performance differences between the three topologies are minor. Accuracy is much more dependent upon the quality of the resistors and amplifiers that are used and less dependent on which of the three circuits are chosen. For example, input offset voltage error is essentially the same for all three circuits. To a first order approximation, it is equal to total gain times the difference in offset between the two amplifiers that are directly tied to the sensor. Errors due to resistor tolerances are somewhat dependent upon circuit topology. However, they are much more dependent upon the choice of resistors. Choosing 1% resistors rather than 5% resistors has a much larger impact on performance than the minor differences that result from circuit topology. Assuming a zero pressure offset adjustment, any of these circuits with an MPX2000 series sensor, 1% resistors and an MC33274 amplifier results in a 5% pressure to voltage translation from 0 to 50 C. Software calibration can significantly improve these numbers and eliminate the need for analog trim. CONCLUSION Although the classic instrumentation amplifier is the best known and most frequently used sensor interface amplifier, it is generally not the optimal choice for inexpensive circuits made from discrete components. The circuit that is shown in Motorola Sensor Device Data Figure 4 performs the same interface function with significantly fewer components, less board space and at a lower cost. It is generally the preferred interface topology for MPX2000 series semiconductor pressure sensors. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-287 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Barometric Pressure Measurement Using Semiconductor Pressure Sensors AN1326 Prepared by: Chris Winkler and Jeff Baum Discrete Applications Engineering Freescale Semiconductor, Inc... ABSTRACT The most recent advances in silicon micromachining technology have given rise to a variety of low-cost pressure sensor applications and solutions. Certain applications had previously been hindered by the high-cost, large size, and overall reliability limitations of electromechanical pressure sensing devices. Furthermore, the integration of on-chip temperature compensation and calibration has allowed a significant improvement in the accuracy and temperature stability of the sensor output signal. This technology allows for DIGIT1 the development of both analog and microcomputer-based systems that can accurately resolve the small pressure changes encountered in many applications. One particular application of interest is the combination of a silicon pressure sensor and a microcontroller interface in the design of a digital barometer. The focus of the following documentation is to present a low-cost, simple approach to designing a digital barometer system. DIGIT2 DIGIT3 DIGIT4 MCU SIGNAL CONDITIONING PRESSURE SENSOR Figure 1. Barometer System REV 1 3-288 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... INTRODUCTION AN1326 Table 1. Altitude versus Pressure Data Figure 1 shows the overall system architecture chosen for this application. This system serves as a building block, from which more advanced systems can be developed. Enhanced accuracy, resolution, and additional features can be integrated in a more complex design. There are some preliminary concerns regarding the measurement of barometric pressure which directly affect the design considerations for this system. Barometric pressure refers to the air pressure existing at any point within the earth's atmosphere. This pressure can be measured as an absolute pressure, (with reference to absolute vacuum) or can be referenced to some other value or scale. The meteorology and avionics industries traditionally measure the absolute pressure, and then reference it to a sea level pressure value. This complicated process is used in generating maps of weather systems. The atmospheric pressure at any altitude varies due to changing weather conditions over time. Therefore, it can be difficult to determine the significance of a particular pressure measurement without additional information. However, once the pressure at a particular location and elevation is determined, the pressure can be calculated at any other altitude. Mathematically, atmospheric pressure is exponentially related to altitude. This particular system is designed to track variations in barometric pressure once it is calibrated to a known pressure reference at a given altitude. For simplification, the standard atmospheric pressure at sea level is assumed to be 29.9 in-Hg. "Standard" barometric pressure is measured at particular altitude at the average weather conditions for that altitude over time. The system described in this text is specified to accurately measure barometric pressure variations up to altitudes of 15,000 ft. This altitude corresponds to a standard pressure of approximately 15.0 in-Hg. As a result of changing weather conditions, the standard pressure at a given altitude can fluctuate approximately 1 in-Hg. in either direction. Table 1 indicates standard barometric pressures at several altitudes of interest. Altitude (Ft.) Pressure (in-Hg) 0 29.92 500 29.38 1,000 28.85 6,000 23.97 10,000 20.57 15,000 16.86 SYSTEM OVERVIEW In order to measure and display the correct barometric pressure, this system must perform several tasks. The measurement strategy is outlined below in Figure 2. First, pressure is applied to the sensor. This produces a proportional differential output voltage in the millivolt range. This signal must then be amplified and level-shifted to a single-ended, microcontroller (MCU) compatible level (0.5 - 4.5 V) by a signal conditioning circuit. The MCU will then sample the voltage at the analog-to-digital converter (A/D) channel input, convert the digital measurement value to inches of mercury, and then display the correct pressure via the LCD interface. This process is repeated continuously. There are several significant performance features implemented into this system design. First, the system will digitally display barometric pressure in inches of mercury, with a resolution of approximately one-tenth of an inch of mercury. In order to allow for operation over a wide altitude range (0 - 15,000 ft.), the system is designed to display barometric pressures ranging from 30.5 in-Hg. to a minimum of 15.0 in-Hg. The display will read "lo" if the pressure measured is below 30.5 in-Hg. These pressures allow for the system to operate with the desired resolution in the range from sea-level to approximately 15,000 ft. An overview of these features is shown in Table 2. Table 2. System Features Overview Display Units MPX2100AP PRESSURE SENSOR SIGNAL COND. AMPLIFIER MC68HC11E9 MICRO- CONTROLLER CLOCK SYNCH in-Hg Resolution 0.1 in-Hg. System Range 15.0 - 30.5 in-Hg. Altitude Range 0 - 15,000 ft. DATA DESIGN OVERVIEW 4-DIGIT LCD & MC145453 DISPLAY DRIVER Figure 2. Barometer System Block Diagram Motorola Sensor Device Data The following sections are included to detail the system design. The overall system will be described by considering the subsystems depicted in the system block diagram, Figure 2. The design of each subsystem and its function in the overall system will be presented. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-289 Freescale Semiconductor, Inc. AN1326 Table 3. MPX2100AP Electrical Characteristics Characteristic Symbol Minimum Pressure Range POP 0 Supply Voltage VS Full Scale Span VFSS Zero Pressure Offset 38.5 Max Unit 100 kPa 10 16 Vdc 40 41.5 mV 1.0 mV Voff Sensitivity Freescale Semiconductor, Inc... Typical S 0.4 mv/kPa Linearity 0.05 %FSS Temperature Effect on Span 0.5 %FSS Temperature Effect on Offset 0.2 %FSS Pressure Sensor The first and most important subsystem is the pressure transducer. This device converts the applied pressure into a proportional, differential voltage signal. This output signal will vary linearly with pressure. Since the applied pressure in this application will approach a maximum level of 30.5 in-Hg. (100 kPa) at sea level, the sensor output must have a linear output response over this pressure range. Also, the applied pressure must be measured with respect to a known reference pressure, preferably absolute zero pressure (vacuum). The device should also produce a stable output over the entire operating temperature range. The desired sensor for this application is a temperature compensated and calibrated, semiconductor pressure transducer, such as the Motorola MPXM2102A series sensor family. The MPX2000 series sensors are available in full-scale pressure ranges from 10 kPa (1.5 psi) to 200 kPa (30 psi). Furthermore, they are available in a variety of pressure configurations (gauge, differential, and absolute) and porting options. Because of the pressure ranges involved with barometric pressure measurement, this system will employ an MPXM2102AS (absolute with single port). This device will produce a linear voltage output in the pressure range of 0 to 100 kPa. The ambient pressure applied to the single port will be measured with respect to an evacuated cavity (vacuum reference). The electrical characteristics for this device are summarized in Table 3. As indicated in Table 3, the sensor can be operated at different supply voltages. The full-scale output of the sensor, which is specified at 40 mV nominally for a supply voltage of 10 Vdc, changes linearly with supply voltage. All non-digital circuitry is operated at a regulated supply voltage of 8 Vdc. Therefore, the full-scale sensor output (also the output of the sensor at sea level) will be approximately 32 mV. 8 10 40 mV (30.5 * 15.0)in-Hg * 10 steps + 155 steps Hg The span voltage can now be determined. The resolution provided by an 8-bit A/D converter with low and high voltage references of zero and five volts, respectively, will detect 19.5 mV of change per step. V RH + 5 V, V RL +0 V Sensor Output at 30.5 in-Hg = 32.44 mV Sensor Output at 15.0 in-Hg = 16.26 mV Sensor Output = SO = 16.18 mV The sensor output voltage at the systems minimum range (15 in-Hg.) is approximately 16.2 mV. Thus, the sensor output over the intended range of operations is expected to vary from 32 to 16.2 mV. These values can vary slightly for each sensor as the offset voltage and full-scale span tolerances indicate. 3-290 Signal Conditioning Circuitry In order to convert the small-signal differential output signal of the sensor to MCU compatible levels, the next subsystem includes signal conditioning circuitry. The operational amplifier circuit is designed to amplify, level-shift, and ground reference the output signal. The signal is converted to a single-ended, 0.5 - 4.5 Vdc range. The schematic for this amplifier is shown in Figure 3. This particular circuit is based on classic instrumentation amplifier design criteria. The differential output signal of the sensor is inverted, amplified, and then level-shifted by an adjustable offset voltage (through Roffset1). The offset voltage is adjusted to produce 0.5 volts at the maximum barometric pressure (30.5 in-Hg.). The output voltage will increase for decreasing pressure. If the output exceeds 5.1 V, a zener protection diode will clamp the output. This feature is included to protect the A/D channel input of the MCU. Using the transfer function for this circuit, the offset voltage and gain can be determined to provide 0.1 in-Hg of system resolution and the desired output voltage level. The calculation of these parameters is illustrated below. In determining the amplifier gain and range of the trimmable offset voltage, it is necessary to calculate the number of steps used in the A/D conversion process to resolve 0.1 in-Hg. Gain V + 3.04 DSO + 187 Note: 30.5 in-Hg and 15.0 in-Hg are the assumed maximum and minimum absolute pressures, respectively. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. a 16-bit timer, an SPI (Serial Peripheral Interface - synchronous), and SCI (Serial Communications Interface - asynchronous), and a maximum of 40 I/O lines. This device is available in several package configurations and product variations which include additional RAM, EEPROM, and/or I/O capability. The software used in this application was developed using the MC68HC11 EVB development system. The following software algorithm outlines the steps used to perform the desired digital processing. This system will convert the voltage at the A/D input into a digital value, convert this measurement into inches of mercury, and output this data serially to an LCD display interface (through the on-board SPI). This process is outlined in greater detail below: This gain is then used to determine the appropriate resistor values and offset voltage for the amplifier circuit defined by the transfer function shown below. Freescale Semiconductor, Inc... V out +* R2 R1 )1 * AN1326 DV ) V off V is the differential output of the sensor. The gain of 187 can be implemented with: R1 R3 = 121 R2 R4 = 22.6 k . Choosing Roffset1 to be 1 k and Roffset2 to be 2.5 k , Vout is 0.5 V at the presumed maximum barometric pressure of 30.5 in-Hg. The maximum pressure output voltage can be trimmed to a value other than 0.5 V, if desired via Roffset1. In addition, the trimmable offset resistor is incorporated to provide offset calibration if significant offset drift results from large weather fluctuations. The circuit shown in Figure 3 employs an MC33272 (low-cost, low-drift) dual operational amplifier IC. In order to control large supply voltage fluctuations, an 8 Vdc regulator, MC78L08ACP, is used. This design permits use of a battery for excitation. 1. Set up and enable A/D converter and SPI interface. 2. Initialize memory locations, initialize variables. 3. Make A/D conversion, store result. 4. Convert digital value to inches of mercury. 5. Determine if conversion is in system range. 6a. Convert pressure into decimal display digits. 6b. Otherwise, display range error message. 7. Output result via SPI to LCD driver device. The signal conditioned sensor output signal is connected to pin PE5 (Port E-A/D Input pin). The MCU communicates to the LCD display interface via the SPI protocol. A listing of the assembly language source code to implement these tasks is included in the appendix. In addition, the software can be downloaded directly from the Motorola MCU Freeware Bulletin Board (in the MCU directory). Further information is included at the beginning of the appendix. Microcontroller Interface The low cost of MCU devices has allowed for their use as a signal processing tool in many applications. The MCU used in this application, the MC68HC11, demonstrates the power of incorporating intelligence into such systems. The on-chip resources of the MC68HC11 include: an 8 channel, 8-bit A/D, +12 V U1 MC78L08ACP IN VS = 8 V OUT C1 0.33 F U2B MC33272 MPXM2102AS GROUND 3 C2 0.33 F S- 2 Vout + - 1 5.1 V 2 ZENER 4 1 1 2 S+ Roffset1 1k Roffset2 2.5 k 1 1 1 2 R3 121 U2A MC33272 + - 2 2 R4 22.6 k R2 22.6 k W 1 2 R1 121 Figure 3. Signal Conditioning Circuit Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-291 Freescale Semiconductor, Inc. AN1326 LCD Interface In order to digitally display the barometric pressure conversion, a serial LCD interface was developed to communicate with the MCU. This system includes an MC145453 CMOS serial interface/LCD driver, and a 4-digit, non-multiplexed LCD. In order for the MCU to communicate correctly with the interface, it must serially transmit six bytes for each conversion. This includes a start byte, a byte for each of the four decimal display digits, and a stop byte. For formatting purposes, decimal points and blank digits can be displayed through appropriate bit patterns. The control of display digits and data transmission is executed in the source code through subroutines BCDCONV, LOOKUP, SP12LCD, and TRANSFER. A block diagram of this interface is included below. CONCLUSION Freescale Semiconductor, Inc... This digital barometer system described herein is an excellent example of a sensing system using solid state components and software to accurately measure barometric pressure. This system serves as a foundation from which more complex systems can be developed. The MPXM2102A series pressure sensors provide the calibration and temperature compensation necessary to achieve the desired accuracy and interface simplicity for barometric pressure sensing applications. +5 V BP BP 20 VDD BP IN BP OUT DIGIT1 OSC IN DIGIT2 DIGIT3 DIGIT4 OUT 33 MC145453 MC68HC11 MOSI SCK DATA CLOCK VSS OUT1 1 Figure 4. LCD Display Interface Diagram 3-292 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1326 APPENDIX MC68HC11 Barometer Software Available on: Freescale Semiconductor, Inc... Motorola Electronic Bulletin Board MCU Freeware Line 8-bit, no parity, 1 stop bit 1200/300 baud (512) 891-FREE (3733) * * * * * * * * * * * BAROMETER APPLICATIONS PROJECT - Chris Winkler Developed: October 1st, 1992 - Motorola Discrete Applications This code will be used to implement an MC68HC11 Micro-Controller as a processing unit for a simple barometer system. The HC11 will interface with an MPX2100AP to monitor,store and display measured Barometric pressure via the 8-bit A/D channel The sensor output (32mv max) will be amplified to .5 - 2.5 V dc The processor will interface with a 4-digit LCD (FE202) via a Motorola LCD driver (MC145453) to display the pressure within +/- one tenth of an inch of mercury. The systems range is 15.0 - 30.5 in-Hg * * * * A/D & CPU Register Assignment This code will use index addressing to access the important control registers. All addressing will be indexed off of REGBASE, the base address for these registers. REGBASE EQU ADCTL ADR2 ADOPT PORTB PORTD DDRD SPCR SPSR SPDR $1000 EQU EQU EQU EQU EQU EQU EQU EQU EQU $30 $32 $39 $04 $08 $09 $28 $29 $2A * register * * * * * * * * * base of control register offset of A/D control register offset of A/D results register offset for A/D option register location Location of PORTB used for conversion PORTD Data Register Index offset of Data Direction Reg. offset of SPI Control Reg. offset of SPI Status Reg. offset of SPI Data Reg. * * * * User Variables The following locations are used to store important measurements and calculations used in determining the altitude. They are located in the lower 256 bytes of user RAM DIGIT1 DIGIT2 DIGIT3 DIGIT4 COUNTER POFFSET SENSOUT RESULT FLAG EQU EQU EQU EQU EQU EQU EQU EQU * * * * * * * * * * * * * MAIN PROGRAM The conversion process involves the following steps: * * * This process is continually repeated as the loop CONVERT runs unconditionally through BRA (the BRANCH ALWAYS statement) Repeats to step 3 indefinitely. $0001 $0002 $0003 $0004 $0005 $0010 $0012 $0014 EQU * * * * * * * * $0016 BCD blank digit (not used) BCD tens digit for pressure BCD tenths digit for pressure BCD ones digit for pressure Variable to send 5 dummy bytes Storage Location for max pressure offset Storage location for previous conversion Storage of Pressure(in Hg) in hex format * Determines if measurement is within range 1. 2. 3. 4. 5. a. b. 6. 7. 8. Motorola Sensor Device Data Set-Up SPI device- Set-Up A/D, Constants Read A/D, store sample Convert into in-Hg Determine FLAG condition IN_HG Display error Continue Conversion Convert hex to BCD format BCDCONV Convert LCD display digits Output via SPI to LCD SPI_CNFG SET_UP ADCONV IN_HG ERROR INRANGE LOOKUP SPI2LCD www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-293 Freescale Semiconductor, Inc. AN1326 CONVERT BSR * * * * ORG LDX BSR BSR ADCONV BSR BSR DELAY IN_HG * DESIGNATES START OF MEMORY MAP FOR USER CODE * Location of base register for indirect adr * Set-up SPI Module for data X-mit to LCD * Power-Up A/D, initialize constants * Calls subroutine to make an A/D conversion * Delay routine to prevent LCD flickering * Converts hex format to in of Hg The value of FLAG passed from IN_HG is used to determine If a range error has occurred. The following logical statements are used to either allow further conversion or jump to a routine to display a range error message. LDAB CMPB BEQ BSR BRA * Freescale Semiconductor, Inc... $C000 #REGBASE SPI_CNFG SET_UP FLAG #$80 INRANGE ERROR OUTPUT * * * system * * Branches Determines if an range Error has ocurred If No Error detected (FLAG=$80) then will continue conversion process If error occurs (FLAG<>80), branch to ERROR to output ERROR code to display No Error Detected, Conversion Process Continues INRANGE JSR BCDCONV JSR LOOKUP OUTPUT JSR SPI2LCD * Output transmission to LCD BRA CONVERT * Continually converts using Branch Always * * * Subroutine SPI_CNFG Purpose is to initialize SPI for transmission and clear the display before conversion. SPI_CNFG BSET PORTD,X #$20 LDAA #$38 STAA DDRD,X LDAA STAA #$5D SPCR,X LDAA STAA LDAA #$5 COUNTER SPSR,X CLRA ERASELCD JSR * Converts Hex Result to BCD * Uses Look-Up Table for BCD-Decimal * Set SPI SS Line High to prevent glitch * Initializing Data Direction for Port D * Selecting SS, MOSI, SCK as outputs only * Initialize SPI-Control Register * selecting SPE,MSTR,CPOL,CPHA,CPRO * sets counter to X-mit 5 blank bytes * Must read SPSR to clear SPIF Flag * Transmission of Blank Bytes to LCD TRANSFER * Calls subroutine to transmit DEC COUNTER BNE ERASELCD RTS * * * SET_UP Subroutine SET_UP Purpose is to initialize constants and to power-up A/D and to initialize POFFSET used in conversion purposes. LDAA #$90 * selects ADPU bit in OPTION register STAA ADOPT,X * Power-Up of A/D complete LDD #$0131+$001A * Initialize POFFSET STD POFFSET * POFFSET = 305 - 25 in hex LDAA #$00 * or Pmax + offset voltage (5 V) RTS * * * Subroutine DELAY Purpose is to delay the conversion process to minimize LCD flickering. DELAY OUTLOOP LDB INLOOP DECB LDA #$FF #$FF BNE DECA BNE RTS INLOOP * Loop for delay of display * Delay = clk/255*255 OUTLOOP * * * Subroutine ADCONV Purpose is to read the A/D input, store the conversion into SENSOUT. For conversion purposes later. ADCONV LDX 3-294 #REGBASE * loads base register for indirect addressing LDAA #$25 STAA ADCTL,X * initializes A/D cont. register SCAN=1,MULT=0 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. WTCONV * * * * IN_HG Freescale Semiconductor, Inc... TOHIGH BRCLR ADCTL,X #$80 WTCONV LDAB ADR2,X CLRA STD SENSOUT RTS AN1326 * Wait for completion of conversion flag * Loads conversion result into Accumulator * Stores conversion as SENSOUT Subroutine IN_HG Purpose is to convert the measured pressure SENSOUT, into units of in-Hg, represented by a hex value of 305-150 This represents the range 30.5 - 15.0 in-Hg LDD POFFSET * Loads maximum offset for subtraction SUBD SENSOUT * RESULT = POFFSET-SENSOUT in hex format STD RESULT * Stores hex result for P, in Hg CMPD #305 BHI TOHIGH LDAB TOLOW CMPD BLO #150 TOLOW LDAB STAB BRA #$80 FLAG END_CONV #$FF STAB BRA FLAG END_CONV LDAB STAB #$00 FLAG END_CONV RTS * * * * Subroutine ERROR This subroutine sets the display digits to output an error message having detected an out of range measurement in the main program from FLAG ERROR SET_HI LDAB LDAB STAB STAB #$00 DIGIT1 DIGIT4 * Initialize digits 1,4 to blanks LDAB CMPB BNE FLAG #$00 SET_HI * FLAG is used to determine * if above or below range. * If above range GOTO SET_HI LDAB STAB LDAB STAB BRA #$0E DIGIT2 #$7E DIGIT3 END_ERR * ELSE display LO on display * Set DIGIT2=L,DIGIT3=O #$37 STAB LDAB STAB DIGIT2 #$30 DIGIT3 * GOTO exit of subroutine * Set DIGIT2=H,DIGIT3=1 END_ERR RTS * * * * * Subroutine BCDCONV Purpose is to uses standard Divide HEX/10 process until BCDCONV LDAA CONVLP * LDX #$00 STAA STAA STAA LDY LDD #$A IDIV STAB DEY CPX XGDX BNE LDX RTS convert ALTITUDE from hex to BCD HEX-BCD conversion scheme store Remainder, swap Q & R, repeat remainder = 0. * Default Digits 2,3,4 to 0 DIGIT2 DIGIT3 DIGIT4 #DIGIT4 RESULT * Conversion starts with lowest digit * Load voltage to be converted * Divide hex digit by 10 * Quotient in X, Remainder in D * stores 8 LSB's of remainder as BCD digit 0,Y #$0 * Determines if last digit stored * Exchanges remainder & quotient CONVLP #REGBASE * Reloads BASE into main program Subroutine LOOKUP Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-295 Freescale Semiconductor, Inc. AN1326 * * * * * Purpose is to implement a Look-Up conversion The BCD is used to index off of TABLE where the appropriate hex code to display that decimal digit is contained. DIGIT4,3,2 are converted only. LOOKUP LDX TABLOOP DEX #DIGIT1+4 LDY LDAB ABY LDAA STAA CPX BNE #TABLE 0,X 0,Y 0,X #DIGIT2 TABLOOP * Counter starts at 5 * Start with Digit4 * Loads table base into Y-pointer * Loads current digit into B * Adds to base to index off TABLE * Stores HEX segment result in A * Loop condition complete, DIGIT2 Converted RTS Freescale Semiconductor, Inc... * * * * * * Subroutine SPI2LCD Purpose is to output digits to LCD via SPI The format for this is to send a start byte, four digits, and a stop byte. This system will have 3 significant digits: blank digit and three decimal digits. * Sending LCD Start Byte SPI2LCD LDX #REGBASE LDAA SPSR,X LDAA #$02 BSR TRANSFER * LDAA ORA STAA DIGIT3 #$80 DIGIT3 LDAA STAA #$00 DIGIT1 * Reads to clear SPIF flag * Byte, no colon, start bit * Transmit byte Initializing decimal point & blank digit * Sets MSB for decimal pt. * after digit 3 * Set 1st digit as blank * Sending four decimal digits LDY LDAA BSR INY CPY BNE DLOOP #DIGIT1 0,Y TRANSFER * Pointer set to send 4 bytes * Loads digit to be x-mitted * Transmit byte * Branch until both bytes sent #DIGIT4+1 DLOOP * Sending LCD Stop Byte LDAA BSR #$00 TRANSFER * end byte requires all 0's * Transmit byte RTS * * * Subroutine TRANSFER Purpose is to send data bits to SPI and wait for conversion complete flag bit to be set. TRANSFER LDX XMIT #REGBASE BCLR STAA BRCLR BSET LDAB PORTD,X #$20 * Assert SS Line to start X-misssion SPDR,X * Load Data into Data Reg.,X-mit SPSR,X #$80 XMIT * Wait for flag PORTD,X #$20 * DISASSERT SS Line SPSR,X * Read to Clear SPI Flag RTS * * Location for FCB memory for look-up table There are 11 possible digits: blank, 0-9 TABLE 3-296 FCB END $7E,$30,$6D,$79,$33,$5B,$5F,$70,$7F,$73,$00 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1513 Mounting Techniques and Plumbing Options of Motorola's MPX Series Pressure Sensors Prepared by: Brian Pickard Sensor Products Division Semiconductor Products Sector Freescale Semiconductor, Inc... INTRODUCTION Motorola offers a wide variety of ported, pressure sensing devices which incorporate a hose barb and mounting tabs. They were designed to give the widest range of design flexibility. The hose barbs are 1/8 (3 mm) diameter and the tabs have #6 mounting holes. These sizes are very common and should make installation relatively simple. More importantly, and often overlooked, are the techniques used in mounting and adapting the ported pressure sensors. This application note provides some recommendations on types of fasteners for mounting, how to use them with Motorola sensors, and identifies some suppliers. This document also recommends a variety of hoses, hose clamps, and their respective suppliers. This information applies to all Motorola MPX pressure sensors with ported packages, which includes the packages shown in Figure 1. A review of recommended mounting hardware, mounting torque, hose applications, and hose clamps is also provided for reference. MOUNTING HARDWARE Mounting hardware is an integral part of package design. Different applications will call for different types of hardware. When choosing mounting hardware, there are three important factors: * permanent versus removable * application * cost The purpose of mounting hardware is not only to secure the sensor in place, but also to remove the stresses from the sensor leads. In addition, these stresses can be high if the hose is not properly secured to the sensor port. Screws, rivets, push-pins, and clips are a few types of hardware that can be used. Refer to Figure 2. Single Side Port Differential Port Axial Port Stovepipe Port Screw Figure 1. MPX Pressure Sensors with Ported Packages Rivet Push-Pin Figure 2. Mounting Hardware REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-297 Freescale Semiconductor, Inc. AN1513 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. -T- C A E -Q- U DIM A B C D E F G J K N P Q R S U V POSITIVE PRESSURE N V B R PORT #2 VACUUM PIN 1 -P- 0.25 (0.010) M T Q M 1 2 3 4 S K F Freescale Semiconductor, Inc... J T P M Q S S NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5, 1982. 2. CONTROLLING DIMENSION: INCH. -A- -T- U L R H N PORT #1 POSITIVE PRESSURE -Q- B 1 2 3 4 PIN 1 K -P- 0.25 (0.010) J M T Q S S F G D 4 PL 0.13 (0.005) C MILLIMETERS MIN MAX 27.43 28.45 18.80 19.30 16.00 16.51 0.41 0.51 4.06 4.57 1.22 1.63 2.54 BSC 0.36 0.41 5.59 6.10 1.78 2.03 3.81 4.06 3.81 4.06 11.18 11.68 17.65 18.42 21.34 21.84 4.62 4.92 G D 4 PL 0.13 (0.005) SEATING PLANE INCHES MIN MAX 1.080 1.120 0.740 0.760 0.630 0.650 0.016 0.020 0.160 0.180 0.048 0.064 0.100 BSC 0.014 0.016 0.220 0.240 0.070 0.080 0.150 0.160 0.150 0.160 0.440 0.460 0.695 0.725 0.840 0.860 0.182 0.194 M T S S Q DIM A B C D F G H J K L N P Q R S U INCHES MIN MAX 1.145 1.175 0.685 0.715 0.305 0.325 0.016 0.020 0.048 0.064 0.100 BSC 0.182 0.194 0.014 0.016 0.695 0.725 0.290 0.300 0.420 0.440 0.153 0.159 0.153 0.159 0.230 0.250 0.220 0.240 0.910 BSC MILLIMETERS MIN MAX 29.08 29.85 17.40 18.16 7.75 8.26 0.41 0.51 1.22 1.63 2.54 BSC 4.62 4.93 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 5.84 6.35 5.59 6.10 23.11 BSC S Figure 3. Case Outline Drawings Top: Case 371D-03, Issue C Bottom: Case 350-05, Issue J To mount any of the devices except Case 371-07/08 and 867E) to a flat surface such as a circuit board, the spacing and diameter for the mounting holes should be made according to Figure 3. Mounting Screws Mounting screws are recommended for making a very secure, yet removable connection. The screws can be either metal or nylon, depending on the application. The holes are 0.155 diameter which fits a #6 machine screw. The screw can be threaded directly into the base mounting surface or go through the base and use a flat washer and nut (on a circuit board) to secure to the device. MOUNTING TORQUE The torque specifications are very important. The sensor package should not be over tightened because it can crack, causing the sensor to leak. The recommended torque specification for the sensor packages are as follows: 3-298 Port Style Single side port: port side down port side up Differential port (dual port) Axial side port Torque Range 3 - 4 in - lb 6 - 7 in - lb 9 - 10 in - lb 9 - 10 in - lb The torque range is based on installation at room temperature. Since the sensor thermoplastic material has a higher TCE (temperature coefficient of expansion) than common metals, the torque will increase as temperature increases. Therefore, if the device will be subjected to very low temperatures, the torque may need to be increased slightly. If a precision torque wrench is not available, these torques all work out to be roughly 1/2 of a turn past "finger tight" (contact) at room temperature. Tightening beyond these recommendations may damage the package, or affect the performance of the device. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Nylon Screws Motorola recommends the use of #6 - 32 nylon screws as a hardware option. However, they should not be torqued excessively. The nylon screw will twist and deform under higher than recommended torque. These screws should be used with a nylon nut. Freescale Semiconductor, Inc... Rivets Rivets are excellent fasteners which are strong and very inexpensive. However, they are a permanent connection. Plastic rivets are recommended because metal rivets may damage the plastic package. When selecting a rivet size, the most important dimension, besides diameter, is the grip range. The grip range is the combined thickness of the sensor package and the thickness of the mounting surface. Package thicknesses are listed below. Port Style Thickness, a Single side port Dual side port Axial side port Stovepipe port 0.321 (8.15 mm) 0.420 (10.66 mm) 0.321 (8.15 mm) (Does not apply) AN1513 listed later in this application note. Two brands of vinyl hose are: Hose Wall Thickness Max. Press. @ 70F (24C) Max. Temp. (F)/(C) Clippard #3814-1 Herco Clear #0500-037 1/16 1/16 105 54 100/(38) 180/(82) Tygon tubing is slightly more expensive than vinyl, but it is the most common brand, and it is also very flexible. It also is recommended for use at room temperature and applications below 50 psig. This tubing is also recommended for applications where the hose may be removed and reattached several times. This tubing should also be used with a hose clamp. Grip Range = a + b Wall Thickness Max. Press. @ 73F (25C) Max. Temp. (F)/(C) 1/16 62 165/(74) a b Tubing Tygon B-44-3 Push-Pins Plastic push pins or ITW FasTex "Christmas Tree" pins are an excellent way to make a low cost and easily removable connection. However, these fasteners should not be used for permanent connections. Remember, the fastener should take all of the static and dynamic loads off the sensor leads. This type of fastener does not do this completely. Urethane tubing is the most expensive of the four types described herein. It can be used at higher pressures (up to 100 psig) and temperatures up to 100F (38C). It is flexible, although its flexibility is not as good as vinyl or Tygon. Urethane tubing is very strong and it is not necessary to use a hose clamp, although it is recommended. Two brands of urethane hose are: HOSE APPLICATIONS By using a hose, a sensor can be located in a convenient place away from the actual sensing location which could be a hazardous and difficult area to reach. There are many types of hoses on the market. They have different wall thicknesses, working pressures, working temperatures, material compositions, and media compatibilities. All of the hoses referenced here are 1/8 inside diameter and 1/16 wall thickness, which produces a 1/4 outside diameter. Since all the port hose barbs are 1/8, they require 1/8 inside diameter hose. The intent is for use in air only and any questions about hoses for your specific application should be directed to the hose manufacturer. Four main types of hose are available: * Vinyl * Tygon * Urethane * Nylon Vinyl hose is inexpensive and is best in applications with pressures under 50 psig and at room temperature. It is flexible and durable and should not crack or deteriorate with age. This type of hose should be used with a hose clamp such as those Motorola Sensor Device Data Hose Wall Thickness Max. Press. @ 70F (24C) Max. Temp. (F)/(C) Clippard #3814-6 Herco Clear #0585-037 1/16 1/16 105 105 120/(49) 225/(107) Nylon tubing does not work well with Motorola's sensors. It is typically used in high pressure applications with metal fittings (such as compressed air). HOSE CLAMPS Hose clamps should be employed for use with all hoses listed above. They provide a strong connection with the sensor which prevents the hose from working itself off, and also reduces the chance of leakage. There are many types of hose clamps that can be used with the ported sensors. Here are some of the most common hose clamps used with hoses. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-299 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1513 Crimp-on Clamp Nylon Snap Spring Wire Screw-on The two clamps most recommended by Motorola are the crimp-on clamp and the screw-on, Clippard reusable clamp. The crimp-on type clamp is offered from both Ryan Herco (#0929-007) and Clippard (#5000-2). Once crimped in place, it provides a very secure hold, but it is not easily removed and is not reusable. The Clippard, reusable hose clamp is a brass, self-threading clamp, which provides an equally strong grip as the crimp-on type just described. The drawback is the reusable clamp is considerably more expensive. The nylon snap is also reusable, however the size options do not match the necessary outside diameter. The spring wire clamp, common in the automotive industry, and known for its very low cost and ease of use, also has a size matching problem. Custom fit spring wire clamps may provide some cost savings in particular applications. Figure 4. Hose Clamps SUPPLIER LIST Hoses Spring Wire Clamps Bolts Norton-Performance Plastics Worldwide Headquarters 150 Dey Road, Wayne, NJ 07470-4599 USA (201) 596-4700 Telex: 710-988-5834 USA P.O. Box 3660, Akron, OH 44309-3660 USA (216) 798-9240 FAX: (216) 798-0358 RotorClip, Inc. 187 Davidson Avenue Somerset, NJ 08875-0461 1-800-631-5857 Ext. 255 Quality Screw and Nut Company 1331 Jarvis Avenue Elk Grove Village, IL 60007 (312) 593-1600 Rivets and Push-Pins Crimp-on and Nylon Clamps ITW FasTex 195 Algonquin Road Des Plaines, IL 60016 (708) 299-2222 FAX: (708) 390-8727 Ryan Herco Products Corporation P.O. Box 588 Burbank, CA 91503 1-800-423-2589 FAX: (818) 842-4488 Clippard Instrument Laboratory, Inc. 7390 Colerain Rd. Cincinnati, Ohio 45239, USA (513) 521-4261 FAX: (513) 521-4464 Ryan Herco Products Corporation P.O. Box 588 Burbank, CA 91503 1-800-423-2589 FAX: (818) 842-4488 3-300 Crimp-on and Screw-on Clamps Clippard Instrument Laboratory, Inc. 7390 Colerain Rd. Cincinnati, Ohio 45239, USA (513) 521-4261 FAX: (513) 521-4464 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1516 Liquid Level Control Using a Motorola Pressure Sensor Prepared by: JC Hamelain Toulouse Pressure Sensor Laboratory Semiconductor Products Sector, Toulouse, France Freescale Semiconductor, Inc... INTRODUCTION Motorola Discrete Products provides a complete solution for designing a low cost system for direct and accurate liquid level control using an ac powered pump or solenoid valve. This circuit approach which exclusively uses Motorola semiconductor parts, incorporates a piezoresistive pressure sensor with on-chip temperature compensation and a new solid-state relay with an integrated power triac, to drive directly the liquid level control equipment from the domestic 110/220 V 50/60 Hz ac main power line. Depending on the application and pressure range, the sensor may be chosen from the following portfolio. For this application the MPXM2010GS was selected. Device Pressure Range MPXM2010GS 0 to 10 kPa MPXM2053GS 0 to 50 kPa MPXM2102GS 0 to 100 kPa MPXM2202GS 0 to 200 kPa * after proper gain adjustment Application Sensitivity* 0.01 kPa (1 mm H2O) 0.05 kPa (5 mm H2O) 0.1 kPa (10 mm H2O) 0.2 kPa (20 mm H2O) PRESSURE SENSOR DESCRIPTION The MPXM2000 Series pressure sensor integrates on-chip, laser-trimmed resistors for offset calibration and temperature compensation. The pressure sensitive element is a patented, single piezoresistive implant which replaces the four resistor Wheatstone bridge traditionally used by most pressure sensor manufacturers. Pin 3 R1 + VS Roff1 RS1 Rp R2 Pin 2 + Vout X-ducer Pin 4 - Vout Roff2 RS2 Pin 1 MPAK AXIAL PORT CASE 1320A Laser Trimmed On-Chip Figure 1. Pressure Sensor MPXM2000 Series REV 2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-301 Freescale Semiconductor, Inc. AN1516 POWER OPTO ISOLATOR MOC2A60 DESCRIPTION The MOC2A60 is a new Motorola POWER OPTO isolator and consists of a gallium arsenide, infrared emitting diode, which is optically coupled to a zero-cross triac driver and a power triac. It is capable of driving a load of up to 2 A (rms) directly from a line voltage of 220 V (50/60 Hz). Device Schematic 9 3 2 ZVA * Freescale Semiconductor, Inc... 7 CASE 417 PLASTIC PACKAGE * Zero Voltage Activate Circuit 1, 4, 5, 6, 8. 1, 4, 5, 6, 2. 1, 4, 5, 6, 3. 1, 4, 5, 6, 7. 1, 4, 5, 6, 9. No Pin LED Cathode LED Anode Main Terminal Main Terminal Figure 2. MOC2A60 POWER OPTO Isolator SIGNAL CONDITIONING When a full range pressure is applied to the MPXM2010GS, it will provide an output of about 20 mV (at an 8 V supply). Therefore, for an application using only a few percent of the pressure range, the available signal may be as low as a few hundred microvolts. To be useful, the sensor signal must be amplified. This is achieved via a true differential amplifier (A1 and A2) as shown in Figure 4. The GAIN ADJ (500 ohm) resistor, RG, sets the gain to about 200. The differential output of this stage is amplified by a second stage (A3) with a variable OFFSET resistor. This stage performs a differential to single-ended output conversion and references this output to the adjustable offset voltage. This output is then compared to a voltage (VREF = 4 V at TP2) at the input of the third stage (A4). This last amplifier is used as an inverted comparator amplifier with hysteresis (Schmitt trigger) which provides a logic signal (TP3) within a preset range variation of about 10% of the input (selected by the ratio R9/(R9 + R7). If the pressure sensor delivers a voltage to the input of the Schmitt trigger (pin 13) lower than the reference voltage (pin 12), then the output voltage (pin 14) is high and the drive current for the power stage MOC2A60 is provided. When the 3-302 sensor output increases above the reference voltage, the output at pin 14 goes low and no drive current is available. The amplifier used is a Motorola MC33179. This is a quad amplifier with large current output drive capability (more than 80 mA). OUTPUT POWER STAGE For safety reasons, it is important to prevent any direct contact between the ac main power line and the liquid environment or the tank. In order to maintain full isolation between the sensor circuitry and the main power, the solid-state relay is placed between the low voltage circuit (sensor and amplifier) and the ac power line used by the pump and compressor. The output of the last stage of the MC33179 is used as a current source to drive the LED (light emitting diode). The series resistor, R8, limits the current into the LED to approximately 15 mA and guarantees an optimum drive for the power opto-triac. The LD1 (MFOE76), which is an infrared light emitting diode, is used as an indicator to detect when the load is under power. The MOC2A60 works like a switch to turn ON or OFF the pump's power source. This device can drive up to 2 A for an ac load and is perfectly suited for the medium power motors (less than 500 watts) used in many applications. It consists of an opto-triac driving a power triac and has a zero-crossing detection to limit the power line disturbance problems when fast switching selfic loads. An RC network, placed in parallel with the output of the solid-state relay is not required, but it is good design practice for managing large voltage spikes coming from the inductive load commutation. The load itself (motor or solenoid valve) is connected in series with the solid-state relay to the main power line. EXAMPLE OF APPLICATION: ACCURATE LIQUID LEVEL MONITORING The purpose of the described application is to provide an electronic system which maintains a constant liquid level in a tank (within 5 mm H2O). The liquid level is kept constant in the tank by an ac electric pump and a pressure sensor which provides the feedback information. The tank may be of any size. The application is not affected by the volume of the tank but only by the difference in the liquid level. Of course, the maximum level in the tank must correspond to a pressure within the operating range of the pressure sensor. LIQUID LEVEL SENSORS Motorola has developed a piezoresistive pressure sensor family which is very well adapted for level sensing, especially when using an air pipe sensing method. These devices may also be used with a bubbling method or equivalent. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1516 AC Line Control Module Open Pipe Before Calibration Pressure Sensor Air Electrical Pump H Reference Level Liquid Level in the Pipe Freescale Semiconductor, Inc... Figure 3. Liquid Level Monitoring LEVEL SENSING THEORY corresponds to the change in the tank level is measured by the pressure sensor. If a pipe is placed vertically, with one end dipped into a liquid and the other end opened, the level in the pipe will be exactly the same as the level in the tank. However, if the upper end of the pipe is closed off and some air volume is trapped, the pressure in the pipe will vary proportionally with the liquid level change in the tank. For example, if we assume that the liquid is water and that the water level rises in the tank by 10 mm, then the pressure in the pipe will increase by that same value (10 mm of water). A gauge pressure sensor has one side connected to the pipe (pressure side) and the other side open to ambient (in this case, atmospheric) pressure. The pressure difference which PRESSURE SENSOR CHOICE In this example, a level sensing of 10 mm of water is desired. The equivalent pressure in kilo pascals is 0.09806 kPa. In this case, Motorola's temperature compensated 0 - 10 kPa, MPXM2010GS is an excellent choice. The sensor output, with a pressure of 0.09806 kPa applied, will result in 2.0 mV/kPa x 0.09806 = 0.196 mV. The sensing system is designed with an amplifier gain of about 1000. Thus, the conditioned signal voltage given by the module is 1000 x 0.196 mV = 0.196 V with 10 mm - H2O pressure. Table 1. Liquid Level Sensors METHOD SENSOR ADVANTAGE DISADVANTAGES Magnetoresitive Low power, no active electronic Low resolution, range limited Magnetoresitive Very high resolution Complex electronic Ultrasonic Easy to install Need high power, low accuracy Liquid resistivity No active electronic No active electronic Low resolution, liquid dependent String potentiometer Potentiometer Low power, no active electronic Poor linearity, corrosion Pressure Silicon sensors Inexpensive good resolution, wide range measurements Active electronic, need power Liquid weight Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-303 Freescale Semiconductor, Inc. AN1516 P MC78L08 +8 VDC C1 Offset Adjust EEEE EE EEEE EEEE EE EE E EE EE EE EE EE EE EE 3 + 4 - a1 RG 1 + R2 Freescale Semiconductor, Inc... N TP2 6 - + a2 Motor TP1 R3 10 R4 + a3 - 9 Gain ADJ 5 R11 R7 R1 1 4 R10 R9 MPXM2010GS 2 220 VAC Reference ADJ Roff 3 2 TR + 12 R6 8 a4 14 - 13 MOC2A60 R8 R C D1 R5 L TP3 7 11 Figure 4. Electrical Circuit RG = 500 R1, R2 = 100 k R5, R7 = 100 k R3, R4 . . . R6 = 10 k R9 . . . R11 = 10 k R8 = 100 Roff = 25 k var a1 . . . a4 = 1/4 MC33179 D1 = MLED76 MC7808ac = REGL 8 VDC TR = TRANSFORMER 220:12 V C1 = 40 F 40 V Max Liquid Level 10 mm Min 4.3 V Pressure Sensing (TP1) 0.4 V Ref (TP2) 3.7 V 7V Trigger Voltage (TP3) 0 Pump Voltage (AC220V) Sensing for minimum level (pumping into the tank) The sensing probe is tied to the positive pressure port of the sensor. The pump is turned on to fill the tank when the minimum level is reached. Figure 5. Functional Diagram 3-304 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... LEVEL CONTROL MODES This application describes two ways to keep the liquid level constant in the tank; first, by pumping the water out if the liquid level rises above the reference, or second, by pumping the water in if the liquid level drops below the reference. If pumping water out, the pump must be OFF when the liquid level is below the reference level. To turn the pump ON, the sensor signal must be decreased to drop the input to the Schmitt trigger below the reference voltage. To do this, the sensing pipe must be connected to the NEGATIVE pressure port (back or vacuum side) of the sensor. In the condition when the pressure increases (liquid level rises), the sensor voltage will decrease and the pump will turn ON when the sensor output crosses the referenced level. As pumping continues, the level in the tank decreases (thus the pressure on the sensor decreases) and the sensor signal increases back up to the trigger point where the pump was turned OFF. In the case of pumping water into the tank, the pump must be OFF when the liquid level is above the reference level. To turn ON the pump, the sensor signal must be decreased to drive the input Schmitt trigger below the reference voltage. To do this, the sensing pipe must be connected to the POSITIVE pressure port (top side) of the sensor. In this configuration when the pressure on the sensor decreases, (liquid level drops) the sensor voltage also decreases and the pump is turned ON when the signal exceeds the reference. As pumping continues, the water level increases and when the maximum level is reached, the Schmitt trigger turns the pump OFF. ADJUSTMENTS The sensing tube is placed into the water at a distance below the minimum limit level anywhere in the tank. The other Motorola Sensor Device Data AN1516 end of the tube is opened to atmosphere. When the tank is filled to the desired maximum (or minimum) level, the pressure sensor is connected to the tube with the desired port configuration for the application. Then the water level in the tank is the reference. After connecting the tube to the pressure sensor, the module must be adjusted to control the water level. The output voltage at TP1 is preadjusted to about 4 V (half of the supply voltage). When the sensor is connected to the tube, the module output is ON (lighted) or OFF. By adjusting the offset adjust potentiometer the output is just turned into the other state: OFF, if it was ON or the reverse, ON, if it was OFF, (the change in the tank level may be simulated by moving the sensing tube up or down). The reference point TP2 shows the ON/OFF reference voltage, and the switching point of the module is reached when the voltage at TP1 just crosses the value of the TP2 voltage. The module is designed for about 10 mm of difference level between ON and OFF (hysteresis). CONCLUSION This circuit design concept may be used to evaluate Motorola pressure sensors used as a liquid level switch. This basic circuit may be easily modified to provide an analog signal of the level within the controlled range. It may also be easily modified to provide tighter level control ( 2 mm H2O) by increasing the gain of the first amplifier stage (decreasing RG resistor). The circuit is also a useful tool to evaluate the performance of the power optocoupler MOC2A60 when driving ac loads directly. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-305 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1517 Pressure Switch Design with Semiconductor Pressure Sensors Freescale Semiconductor, Inc... Prepared by: Eric Jacobsen and Jeff Baum Sensor Design and Applications Group, Motorola Phoenix, AZ INTRODUCTION them in overall performance (i.e., switching speed, logic-level voltages, etc.). The Pressure Switch concept is simple, as are the additions to conventional signal conditioning circuitry required to provide a pressure threshold (or thresholds) at which the output switches logic state. This logic-level output may be input to a microcontroller, drive an LED, control an electronic switch, etc. The user-programmed threshold (or reference voltage) determines the pressure at which the output state will switch. An additional feature of this minimal component design is an optional user-defined hysteresis setting that will eliminate multiple output transitions when the pressure sensor voltage is comparable to the threshold voltage. This paper presents the characteristics and design criteria for each of the major subsystems of the pressure switch design: the pressure sensor, the signal conditioning (gain) stage, and the comparator output stage. Additionally, an entire section will be devoted to comparator circuit topologies which employ comparator ICs and/or operational amplifiers. A window comparator design (high and low thresholds) is also included. This section will discuss the characteristics and design criteria for each comparator circuit, while evaluating BASIC SENSOR OPERATION Motorola's MPX2000 Series sensors are temperature compensated and calibrated (i.e., offset and full-scale span are precision trimmed) pressure transducers. These sensors are available in full-scale pressure ranges from 10 kPa (1.5 psi) to 200 kPa (30 psi). Although the specifications (see Table 1) in the data sheets apply only to a 10 V supply voltage, the output of these devices is ratiometric with the supply voltage. For example, at the absolute maximum supply voltage rating, 16 V, the sensor will produce a differential output voltage of 64 mV at the rated full-scale pressure of the given sensor. One exception to this is that the full-scale span of the MPX2010 (10 kPa sensor) will be only 40 mV due to the device's slightly lower sensitivity. Since the maximum supply voltage produces the most output voltage, it is evident that even the best case scenario will require some signal conditioning to obtain a usable voltage level. For this specific design, an MPX2100 and 5.0 V supply is used to provide a maximum sensor output of 20 mV. The sensor output is then signal conditioned to obtain a four volt signal swing (span). AAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAA AAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAAAAAA AAAAAAAAAA AAAAA AAAA AAAAA AAAAAAAA Table 1. MPX2100 Electrical Characteristics for VS = 10 V, TA = 25C Characteristic Symbol Minimum Pressure Range POP 0 Supply Voltage VS Full Scale Span VFSS Typical Max Unit 100 kPa 10 16 Vdc 40 41.5 mV Voff 0.05 0.1 mV S 0.4 mV/kPa Linearity 0.05 %FSS Temperature Effect on Span 0.5 %FSS Temperature Effect on Offset 0.2 %FSS Zero Pressure Offset Sensitivity 38.5 REV 2 3-306 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. THE SIGNAL CONDITIONING The amplifier circuitry, shown in Figure 1, is composed of two op-amps. This interface circuit has a much lower component count than conventional quad op amp instrumentation amplifiers. The two op amp design offers the high input impedance, low output impedance, and high gain desired for a transducer interface, while performing a differential to single-ended conversion. The gain is set by the following equation: AN1517 For this specific design, the gain is set to 201 by setting R6 = 20 k and R5 = 100 . Using these values and setting R6 = R3 and R4 = R5 gives the desired gain without loading the reference voltage divider formed by R1 and Roff. The offset voltage is set via this voltage divider by choosing the value of Roff. This enables the user to adjust the offset for each application's requirements. + 1 ) R6 R5 where R6 + R3 and R4 + R5. GAIN Comparator Stage Freescale Semiconductor, Inc... R7 10.0 k VTH Amplifier Stage R1 12.1 k R11 4.75 k R6 20 k R4 100 CN1 U1 R3 20 k R5 100 U1 R10 24.3 k U1 LM324D Roff Q1 MMBT3904LT1 RTH 10 k Vout GND +5 V V4 RH 121 k 3 4 2 1 X1 MPX2100DP Figure 1. Pressure Switch Schematic Pressure Sensor THE COMPARISON STAGE The comparison stage is the "heart" of the pressure switch design. This stage converts the analog voltage output to a digital output, as dictated by the comparator's threshold. The comparison stage has a few design issues which must be addressed: * The threshold for which the output switches must be programmable. The threshold is easily set by dividing the supply voltage with resistors R7 and RTH. In Figure 1, the threshold is set at 2.5 V for R7 = RTH = 10 k. * A method for providing an appropriate amount of hysteresis should be available. Hysteresis prevents multiple transitions from occurring when slow varying signal inputs oscillate about the threshold. The hysteresis can be set by applying positive feedback. The amount of hysteresis is Motorola Sensor Device Data determined by the value of the feedback resistor, RH (refer to equations in the following section). * It is ideal for the comparator's logic level output to swing from one supply rail to the other. In practice, this is not possible. Thus, the goal is to swing as high and low as possible for a given set of supplies. This offers the greatest difference between logic states and will avoid having a microcontroller read the switch level as being in an indeterminate state. * In order to be compatible with CMOS circuitry and to avoid microcontroller timing delay errors, the comparator must switch sufficiently fast. * By using two comparators, a window comparator may be implemented. The window comparator may be used to monitor when the applied pressure is within a set range. By adjusting the input thresholds, the window width can be customized for a given application. As with the single www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-307 Freescale Semiconductor, Inc. AN1517 threshold design, positive feedback can be used to provide hysteresis for both switching points. The window comparator and the other comparator circuits will be explained in the following section. EXAMPLE COMPARATOR CIRCUITS Several comparator circuits were built and evaluated. Comparator stages using the LM311 comparator, LM358 Op-Amp (with and without an output transistor stage), and LM339 were examined. Each comparator was evaluated on output voltage levels (dynamic range), transition speed, and the relative component count required for the complete pressure switch design. This comparison is tabulated in Table 2. LM311 Used in a Comparator Circuit The LM311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an open collector output. A pull-up resistor at the output is all that is needed to obtain a rail-to-rail output. Additionally, the LM311 is a reverse logic circuit; that is, for an input lower than the reference voltage, the output is high. Likewise, when the input voltage is higher than the reference voltage, the output is low. Figure 2 shows a schematic of the LM311 stage with threshold setting resistor divider, hysteresis resistor, and the open-collector pull-up resistor. Table 2 shows the comparator's performance. Based on its performance, this circuit can be used in many types of applications, including interface to microprocessors. The amount of hysteresis can be calculated by the following equations: V Freescale Semiconductor, Inc... VCC REF + R1 R2 ) R2 neglecting the effect of R R1 U1 LM311 Vin RPU V Vout H CC , . R1R2 ) R2R H + REFH R1R2 ) R1R ) R2R H V REFL R2R H + R1R2 ) R1R ) R2R H HYSTERESIS HYSTERESIS V H V CC CC H + VREF * VREFL when the normal state is below V RH R2 V REF , or + VREFH * VREF AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA AAAAAAAAAAA AAAAAA AAAAAAA AAAAAAAAA AAAAA Figure 2. LM311 Comparator Circuit Schematic when the normal state is above V REF . Table 2. Comparator Circuits Performance Characteristics Characteristic LM311 LM358 LM358 w/ Trans. Unit Rise Time 1.40 5.58 2.20 s Fall Time 0.04 6.28 1.30 s VOH 4.91 3.64 5.00 V VOL 61.1 38.0 66.0 mV NEGATIVE NEGATIVE POSITIVE Switching Speeds Output Levels Circuit Logic Type The initial calculation for VREF will be slightly in error due to neglecting the effect of RH. To establish a precise value for VREF (including RH in the circuit), recompute R1 taking into account that VREF depends on R1, R2, and RH. It turns out that when the normal state is below VREF, RH is in parallel with R1: V + R1 o RR2 ) R2 V CC H which is identical to the equation for V REFH 3-308 REF Alternately, when the normal state is above VREF, RH is in parallel with R2: V o RH + R1 R2 ) R2 o R V CC H which is identical to the equation for V REFL REF These two additional equations for VREF can be used to calculate a more precise value for VREF. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. The user should be aware that VREF, VREFH and VREFL are chosen for each application, depending on the desired switching point and hysteresis values. Also, the user must specify which range (either above or below the reference voltage) is the desired normal state (see Figure 3). Referring to Figure 3, if the normal state is below the reference voltage then VREFL (VREFH is only used to calculate a more precise value for VREF as explained above) is below VREF by the desired amount of hysteresis (use VREFL to calculate RH). Alternately, if the normal state is above the reference voltage then VREFH (VREFL is only used to calculate a more precise value for VREF) is above VREF by the desired amount of hysteresis (use VREFH to calculate RH). An illustration of hysteresis and the relationship between these voltages is shown in Figure 3. AN1517 speed is comparable to the LM311's. This enhanced performance does, however, require an additional transistor and base resistor. Referring to Figure 1, note that this comparator topology was chosen for the pressure switch design. The LM324 is a quad op amp that has equivalent amplifier characteristics to the LM358. VCC R1 U1 LM358 Vin Vout Freescale Semiconductor, Inc... VREF (VREFUW) Hysteresis VREFL RH R2 Figure 4. LM358 Comparator Circuit Schematic Normal State VCC R1 VREFH Hysteresis RPU U1 LM358 Vin RB VREF (VREFLW) Vout Q1 MMBT3904LT1 Figure 3. Setting the Reference Voltages RH LM358 Op Amp Used in a Comparator Circuit Figure 4 shows the schematic for the LM358 op amp comparator stage, and Table 2 shows its performance. Since the LM358 is an operational amplifier, it does not have the fast slew-rate of a comparator IC nor the open collector output. Comparing the LM358 and the LM311 (Table 2), the LM311 is better for logic/switching applications since its output nearly extends from rail to rail and has a sufficiently high switching speed. The LM358 will perform well in applications where the switching speed and logic-state levels are not critical (LED output, etc.). The design of the LM358 comparator is accomplished by using the same equations and procedure presented for the LM311. This circuit is also reverse logic. LM358 Op Amp with a Transistor Output Stage Used in a Comparator Circuit The LM358 with a transistor output stage is shown in Figure 5. This circuit has similar performance to the LM311 comparator: its output reaches the upper rail and its switching Motorola Sensor Device Data R2 Figure 5. LM358 with a Transistor Output Stage Comparator Circuit Schematic Like the other two circuits, this comparator circuit can be designed with the same equations and procedure. The values for RB and RPU are chosen to give a 5:1 ratio in Q1's collector current to its base current, in order to insure that Q1 is well-saturated (Vout can pull down very close to ground when Q1 is on). Once the 5:1 ratio is chosen, the actual resistance values determine the desired switching speed for turning Q1 on and off. Also, RPU limits the collector current to be within the maximum specification for the given transistor (see example values in Figure 1). Unlike the other two circuits, this circuit is positive logic due to the additional inversion created at the output transistor stage. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-309 Freescale Semiconductor, Inc. AN1517 LM339 Used in a Window Comparator Circuit HYSTERESIS Using two voltage references to detect when the input is within a certain range is another possibility for the pressure switch design. The window comparator's schematic is shown in Figure 6. The LM339 is a quad comparator IC (it has open collector outputs), and its performance will be similar to that of the LM311. VCC RPU R1 2 4 V U1 LM339 Freescale Semiconductor, Inc... 1 R2 2 Vin VREFLW 1 RHU 1 R5 2 1 R4 2 1 R3 2 1 RHL Figure 6. LM339 Window Comparator Circuit Schematic Obtaining the correct amount of hysteresis and the input reference voltages is slightly different than with the other circuits. The following equations are used to calculate the hysteresis and reference voltages. Referring to Figure 3, VREFUWistheupperwindowreferencevoltageandVREFLW is the lower window reference voltage. Remember that reference voltage and threshold voltage are interchangeable terms. Choose the value for VREFUW and R1 (e.g., 10 k). Then, by voltage division, calculate the total resistance of the combination of R2 and R3 (named R23 for identification) to obtain the desired value for VREFUW, neglecting the effect of RHU: REFUW + R1 R23 ) R23 V CC The amount of hysteresis can be calculated by the following equation: V R23R HU + REFL R1R23 ) R1R ) R23R HU V HU CC Notice that the upper window reference voltage, VREFUW, is now equal to its VREFL value, since at this moment, the input voltage is above the normal state. 3-310 V CC REFLW + R1 o R R3) R2 ) R3 HU V CC , To calculate the hysteresis resistor: The input to the lower comparator is one half Vin (since R4 = R5) when in the normal state. When VREFLW is above one half of Vin (i.e., the input voltage has fallen below the window), RHL parallels R4, thus loading down Vin. The resulting input to the comparator can be referred to as VINL (a lower input voltage). To summarize, when the input is within the window, the output is high and only R4 is connected to ground from the comparator's positive terminal. This establishes one half of Vin to be compared with VREFLW. When the input voltage is below VREFLW, the output is low, and RHL is effectively in parallel with R4. By voltage division, less of the input voltage will fall across the parallel combination of R4 and RHL, demanding that a higher input voltage at Vin be required to make the noninverting input exceed VREFLW. Therefore the following equations are established: HYSTERESIS + VREFLW * VINL Choose R4 = R5 to simplify the design. For the upper window threshold: V HU where R2 + R3 = R23 from above calculation. Vout 7 + 1 2 Set V U1 6 + R1 o RR23) R23 for the lower window threshold choose the value for VREFLW. 5 + 2 REFUW 2 2 VREFUW where VREFL is chosen to give the desired amount of hysteresis for the application. The initial calculation for VREFUW will be slightly in error due to neglecting the effect of RHU. To establish a precise value for VREFUW (including RHU in the circuit), recompute R1 taking into account that VREFUW depends on R2 and R3 and the parallel combination of R1 and RHU. This more precise value is calculated with the following equation: 1 1 + VREFUW * VREFL , R + HL * VINL * VCC (R4 ) R5)V * VREFLW INL R4R5 V REFLW IMPORTANT NOTE: As explained above, because the input voltage is divided in half by R4 and R5, all calculations are done relative to the one half value of Vin. Therefore, for a hysteresis of 200 mV (relative to Vin), the above equations must use one half this hysteresis value (100 mV). Also, if a VREFLW value of 2.0 V is desired (relative to Vin), then 1.0 V for its value should be used in the above equations. The value for VINL should be scaled by one half also. The window comparator design can also be designed using operational amplifiers and the same equations as for the LM339 comparator circuit. For the best performance, however, a transistor output stage should be included in the design. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. TEST/CALIBRATION PROCEDURE 1. Before testing the circuit, the user-defined values for RTH, RH and Roff should be calculated for the desired application. The sensor offset voltage is set by V off + R1 V)offR V off CC . Then, the amplified sensor voltage corresponding to a given pressure is calculated by Freescale Semiconductor, Inc... Vsensor = 201 x 0.0002 x APPLIED PRESSURE + Voff, where 201 is the gain, 0.0002 is in units of V/kPa and APPLIED PRESSURE is in kPa. The threshold voltage, VTH, at which the output changes state is calculated by determining Vsensor at the pressure that causes this change of state: VTH = Vsensor (@ pressure threshold) = ) 4. Connect an additional volt meter to the VTH probe point to verify the threshold voltage. 5. Turn on the supply voltage. 6. With no pressure applied, check to see that Voff is correct by measuring the voltage at the output of the gain stage (the volt meter connected to Pin 4 of CN1). If desired, Voff can be fine tuned by using a potentiometer for Roff. 7. Check to see that the volt meter monitoring VTH displays the desired voltage for the output to change states. Use a potentiometer for RTH to fine tune VTH, if desired. 8. Apply pressure to the sensor. Monitor the sensor's output via the volt meter connected to pin 4 of CN1. The output will switch from low to high when this pressure sensor voltage reaches or exceeds the threshold voltage. 9. If hysteresis is used, with the output high (pressure sensor voltage greater than the threshold voltage), check to see if VTH has dropped by the amount of hysteresis desired. A potentiometer can be used for RH to fine tune the amount of hysteresis. CONCLUSION R TH R7 R AN1517 V TH CC . If hysteresis is desired, refer to the LM311 Used in a Comparator section to determine RH. 2. To test this design, connect a +5 volt supply between pins 3 and 4 of the connector CN1. 3. Connect a volt meter to pins 1 and 4 of CN1 to measure the output voltage and amplified sensor voltage, respectively. Motorola Sensor Device Data The pressure switch design uses a comparator to create a logic level output by comparing the pressure sensor output voltage and a user-defined reference voltage. The flexibility of this minimal component, high performance design makes it compatible with many different applications. The design presented here uses an op amp with a transistor output stage, yielding excellent logic-level outputs and output transition speeds for many applications. Finally, several other comparison stage designs, including a window comparator, are evaluated and compared for overall performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-311 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1518 Using a Pulse Width Modulated Output with Semiconductor Pressure Sensors Prepared by: Eric Jacobsen and Jeff Baum Sensor Design and Applications Group, Motorola Phoenix, AZ Freescale Semiconductor, Inc... INTRODUCTION For remote sensing and noisy environment applications, a frequency modulated (FM) or pulse width modulated (PWM) output is more desirable than an analog voltage. FM and PWM outputs inherently have better noise immunity for these types of applications. Generally, FM outputs are more widely accepted than PWM outputs, because PWM outputs are restricted to a fixed frequency. However, obtaining a stable FM output is difficult to achieve without expensive, complex circuitry. With either an FM or PWM output, a microcontroller can be used to detect edge transitions to translate the time-domain signal into a digital representation of the analog voltage signal. In conventional voltage-to-frequency (V/F) conversions, a voltage-controlled oscillator (VCO) may be used in conjunction with a microcontroller. This use of two time bases, one analog and one digital, can create additional inaccuracies. With either FM or PWM outputs, the microcontroller is only concerned with detecting edge transitions. If a programmable frequency, stable PWM output could be obtained with simple, inexpensive circuitry, a PWM output would be a cost-effective solution for noisy environment/remote sensing applications while incorporating the advantages of frequency outputs. The Pulse Width Modulated Output Pressure Sensor design (Figure 1) utilizes simple, inexpensive circuitry to create an output waveform with a duty cycle that is linear to the applied pressure. Combining this circuitry with a single digital time base to create and measure the PWM signal, results in a stable, accurate output. Two additional advantages of this design are 1) an A/D converter is not required, and 2) since the PWM output calibration is controlled entirely by software, circuit-to-circuit variations due to component tolerances can be nullified. The PWM Output Sensor system consists of a Motorola MPX5000 series pressure sensor, a ramp generator (transistor switch, constant current source, and capacitor), a comparator, and an MC68HC05P9 microcontroller. These subsystems are explained in detail below. + 5.0 V Pulse Train from Micro C2 1.0 F Ramp Generator PWM Output to Micro U2 MDC4010CT1 Q1 MMBT3904LT1 C1 3.3 F R4 4.75 k R5 22.1 k R3 4.75 k U1 LM311D R1 10 k X1 MPX5100DP R2 10 k Comparator Stage Pressure Sensor Figure 1. PWM Output Pressure Sensor Schematic REV 1 3-312 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PRESSURE SENSOR Motorola's MPX5000 series sensors are signal conditioned (amplified), temperature compensated and calibrated (i.e., offset and full-scale span are precision trimmed) pressure transducers. These sensors are available in full-scale pressure ranges of 50 kPa (7.3 psi) and 100 kPa (14.7 psi). With the recommended 5.0 V supply, the MPX5000 series AN1518 produces an output of 0.5 V at zero pressure to 4.5 V at full scale pressure. Referring to the schematic of the system in Figure 1, note that the output of the pressure sensor is attenuated to one-half of its value by the resistor divider comprised of resistors R1 and R2. This yields a span of 2.0 V ranging from 0.25 V to 2.25 V at the non-inverting terminal of the comparator. Table 1 shows the electrical characteristics of the MPX5100. Table 1. MPX5100DP Electrical Characteristics Characteristic Symbol Min Typ Max Unit Pressure Range POP 0 -- 100 kPa Supply Voltage VS -- 5.0 6.0 Vdc Full Scale Span VFSS 3.9 4.0 4.1 V Freescale Semiconductor, Inc... Zero Pressure Offset Voff 0.4 0.5 0.6 V Sensitivity S -- 40 -- mV/kPa Linearity -- - 0.5 -- 0.5 %FSS Temperature Effect on Span -- -1.0 -- 1.0 %FSS Temperature Effect on Offset -- - 50 0.2 50 mV THE RAMP GENERATOR The ramp generator is shown in the schematic in Figure 1. A pulse train output from a microcontroller drives the ramp generator at the base of transistor Q1. This pulse can be accurately controlled in frequency as well as pulse duration via software (to be explained in the microcontroller section). The ramp generator uses a constant current source to charge the capacitor. It is imperative to remember that this current source generates a stable current only when it has approximately 2.5 V or more across it. With less voltage across the current source, insufficient voltage will cause the current to fluctuate more than desired; thus, a design constraint for the ramp generator will dictate that the capacitor can be charged to only approximately 2.5 V, when using a 5.0 V supply. The constant current charges the capacitor linearly by the following equation: Dt DV + IC (1) where t is the capacitor's charging time and C is the capacitance. Referring to Figure 2, when the pulse train sent by the microcontroller is low, the transistor is off, and the current source charges the capacitor linearly. When the pulse sent by the microcontroller is high, the transistor turns on into saturation, discharging the capacitor. The duration of the high part of the pulse train determines how long the capacitor discharges, and thus to what voltage it discharges. This is how the dc offset of the ramp waveform may be accurately controlled. Since the transistor saturates at approximately 60 mV, very little offset is needed to keep the capacitor from discharging completely. Microcontroller Pulse Train Exaggerated Capacitor Discharge Ramp Waveform Ramp Waveform Offset (100 mV) Figure 2. Ideal Ramp Waveform for the PWM Output Pressure Sensor Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-313 Freescale Semiconductor, Inc. AN1518 The PWM output is most linear when the ramp waveform's period consists mostly of the rising voltage edge (see Figure 2). If the capacitor were allowed to completely discharge (see Figure 3), a flat line at approximately 60 mV would separate the ramps, and these "flat spots" may result in non-linearities of the resultant PWM output (after comparing it to the sensor voltage). Thus, the best ramp waveform is produced when one ramp cycle begins immediately after another, and a slight dc offset disallows the capacitor from discharging completely. Microcontroller Pulse Train Freescale Semiconductor, Inc... Exaggerated Capacitor Discharge Ramp Waveform Figure 3. Non Ideal Ramp Waveform for the PWM Output Pressure Sensor The flexibility of frequency control of the ramp waveform via the pulse train sent from the microcontroller allows a programmable-frequency PWM output. Using Equation 1 the frequency (inverse of period) can be calculated with a given capacitor so that the capacitor charges to a maximum V of approximately 2.5 V (remember that the current source needs approximately 2.5 V across it to output a stable current). The importance of software control becomes evident here since the selected capacitor may have a tolerance of 20%. By adjusting the frequency and positive width of the pulse train, the desired ramp requirements are readily obtainable; thus, nullifying the effects of component variances. For this design, the ramp spans approximately 2.4 V from 0.1 V to 2.5 V. At this voltage span, the current source is stable and results in a linear ramp. This ramp span was used for reasons which will become clear in the next section. In summary, complete control of the ramp is achieved by the following adjustments of the microcontroller-created pulse train: * Increase Frequency: Span of ramp decreases. The dc offset decreases slightly. * Decrease Frequency: Span of ramp increases. The dc offset increases slightly. * Increase Pulse Width: The dc offset decreases. Span decreases slightly. * Decrease Pulse Width: The dc offset increases. Span increases slightly. 3-314 THE COMPARATOR STAGE The LM311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an open-collector output. A pull-up resistor at the output is all that is needed to obtain a rail-to-rail output. As Figure 1 shows, the pressure sensor output voltage is input to the non-inverting terminal of the op amp and the ramp is input to the inverting terminal. Therefore, when the pressure sensor voltage is higher than a given ramp voltage, the output is high; likewise, when the pressure sensor voltage is lower than a given ramp voltage, the output is low (refer to Figure 5). As mentioned in the Pressure Sensor section, resistors R1 and R2 of Figure 1 comprise the voltage divider that attenuates the pressure sensor's signal to a 2.0 V span ranging from 0.25 V to 2.25 V. Since the pressure sensor voltage does not reach the ramp's minimum and maximum voltages, there will be a finite minimum and maximum pulse width for the PWM output. These minimum and maximum pulse widths are design constraints dictated by the comparator's slew rate. The system design ensures a minimum positive and negative pulse width of 20 s to avoid nonlinearities at the high and low pressures where the positive duty cycle of the PWM output is at its extremes (refer to Figure 4 ). Depending on the speed of the microcontroller used in the system, the minimum required pulse width may be larger. This will be explained in the next section. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. THE MICROCONTROLLER The microcontroller for this application requires input capture and output compare timer channels. The output capture pin is programmed to output the pulse train that drives the ramp generator, and the input capture pin detects edge transitions to measure the PWM output pulse width. Since software controls the entire system, a calibration routine may be implemented that allows an adjustment of the frequency and pulse width of the pulse train until the desired ramp waveform is obtained. Depending on the speed of the microcontroller, additional constraints on the minimum and maximum PWM output pulse widths may apply. For this design, the software latency incurred to create the pulse train AN1518 at the output compare pin is approximately 40 s. Consequently, the microcontroller cannot create a pulse train with a positive pulse width of less than 40 s. Also, the software that measures the PWM output pulse width at the input capture pin requires approximately 20 s to execute. Referring to Figure 5, the software interrupt that manipulates the pulse train always occurs near an edge detection on the input capture pin (additional software interrupt). Therefore, the minimum PWM output pulse width that can be accurately detected is approximately 60 s (20 s + 40 s). This constrains the minimum and maximum pulse widths more than the slew rate of the comparator which was discussed earlier (refer to Figure 4). V Sets Maximum Pulse Width (Period - 60 s) Freescale Semiconductor, Inc... VSFS VSOFF V Sets Minimum Pulse Width (60 s) Figure 4. Desired Relationship Between the Ramp Waveform and Pressure Sensor Voltage Spans An additional consideration is the resolution of the PWM output. The resolution is directly related to the maximum frequency of the pulse train. In our design, 512 s are required to obtain at least 8-bit resolution. This is determined by the fact that a 4 MHz crystal yields a 2 MHz clock speed in the microcontroller. This, in turn, translates to 0.5 s per clock tick. There are four clock cycles per timer count. This results in 2 s per timer count. Thus, to obtain 256 timer counts (or 8-bit resolution), the difference between the zero pressure and full scale pressure PWM output pulse widths must be at least 512 s (2 s x 256). But since an additional 60 s is needed at both pressure extremes of the output waveform, the total period must be at least 632 s. This translates to a maximum frequency for the pulse train of approximately 1.6 kHz. With this frequency, voltage span of the ramp generator, and value of current charging the capacitor, the minimum capacitor value may be calculated with Equation 1. To summarize: The MC68HC705P9 runs off a 4 MHz crystal. The microcontroller internally divides this frequency by two to yield an internal clock speed of 2 MHz. Motorola Sensor Device Data 1 2 MHz 0.5 ms + clock cycle And, 4 clock cycles = 1 timer count. Therefore, 4 clock cycles timer count 0.5 ms clock cycle s + timer2 mcount For 8-bit resolution, 2 ms timer count 256 counts + 512 ms Adding a minimum of 60 s each for the zero and full scale pressure pulse widths yields 512 s + 60 s + 60 s = 632 s, which is the required minimum pulse train period to drive the ramp generator. Translating this to frequency, the maximum pulse train frequency is thus 1 632 ms www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com + 1.58 kHz . 3-315 Freescale Semiconductor, Inc. AN1518 CALIBRATION PROCEDURE AND RESULTS The following calibration procedure will explain how to systematically manipulate the pulse train to create a ramp that meets the necessary design constraints. The numbers used here are only for this design example. Figure 6 shows the linearity performance achieved by following this calibration procedure and setting up the ramp as indicated by Figures 4 and 5. 1. Start with a pulse train that has a pulse width and frequency that creates a ramp with about 100 mV dc offset and a span smaller than required. In this example the initial pulse width is 84 s and the initial frequency is 1.85 kHz. 2. Decrease the frequency of the pulse train until the ramp span increases to approximately 2.4 V. The ramp span of 2.4 V will ensure that the maximum pulse width at full scale pressure will be at least 60 s less than the total period. Note that by decreasing the frequency of the pulse train, a dc offset will begin to appear. This may result in the ramp looking nonlinear at the top. 3. If the ramp begins to become nonlinear, increase the pulse width to decrease the dc offset. 4. Repeat steps 2 and 3 until the ramp spans 2.4 V and has a dc offset of approximately 100 mV. The dc offset value is not critical, but the bottom of the ramp should have a "crisp" point at which the capacitor stops discharging and begins charging. Simply make sure that the minimum pulse width at zero pressure is at least 60 s. Refer to Figures 4 and 5 to determine if the ramp is sufficient for the application. Freescale Semiconductor, Inc... Microcontroller Pulse Train Ramp Waveform Exaggerated Capacitor Discharge Sensor Voltage Ramp Waveform Offset (100 mV) PWM Output Voltage 650 600 550 500 450 400 350 300 250 200 150 100 50 0 100 90 80 70 60 50 40 Duty Cycle (%) Pulse Width ( s) Figure 5. Relationships Between the PWM Output Pressure Sensor Voltages 30 Pulse Width Duty Cycle 20 10 0 20 40 60 Pressure (kPa) 80 100 0 Figure 6. PWM Output Pressure Sensor Linearity Data 3-316 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1518 CONCLUSION span, the ramp waveform is adjustable in frequency, dc offset, and voltage span. This flexibility enables the effect of component tolerances to be nullified and ensures that ramp span encompasses the pressure sensor output range. The ramp's span can be set to allow for the desired minimum and maximum duty cycle to guarantee a linear dynamic range. Freescale Semiconductor, Inc... The Pulse Width Modulated Output Pressure Sensor uses a ramp generator to create a linear ramp which is compared to the amplified output of the pressure sensor at the input of a comparator. The resulting output is a digital waveform with a duty cycle that is linearly proportional to the input pressure. Although the pressure sensor output has a fixed offset and Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-317 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1525 The A-B-C's of Signal-Conditioning Amplifier Design for Sensor Applications Freescale Semiconductor, Inc... Prepared by: Eric Jacobsen and Jeff Baum Sensor Applications Engineering Motorola Signal Products Division Phoenix, AZ INTRODUCTION Although fully signal-conditioned, calibrated, and temperature compensated monolithic sensor IC's are commercially available today, there are many applications where the flexibility of designing custom signal-conditioning is of great benefit. Perhaps the need for a versatile low-level sensor output is best illustrated by considering two particular cases that frequently occur: (1) the user is in a prototyping phase of development and needs the ability to make changes rapidly to the overall transfer function of the combined sensor/amplifier subsystem, (2) the specific desired transfer function does not exist in a fully signal-conditioned, precision-trimmed sensor product (e.g., a signal-conditioned device is precision trimmed over a different pressure range than that of the application of interest). In such cases, it is obvious that there will always be a need for low-level, nonsignal-conditioned sensors. Given this need, there is also a need for sensor interface amplifier circuits that can signal condition the "raw" sensor output to a usable level. These circuits should also be user friendly, simple, and cost effective. Today's unamplified solid-state sensors typically have an output voltage of tens of millivolts (Motorola's basic 10 kPa pressure sensor, MPX10, has a typical full-scale output of 58 mV, when powered with a 5 V supply). Therefore, a gain stage is needed to obtain a signal large enough for additional processing. This additional processing may include digitization by a microcontroller's analog to digital (A/D) converter, input to a comparator, etc. Although the signal-conditioning circuits described here are applicable to low-level, differential-voltage output sensors in general, the focus of this paper will be on interfacing pressure sensors to amplifier circuits. This paper presents a basic two operational-amplifier signal-conditioning circuit that provides the desired characteristics of an instrumentation amplifier interface: * High input impedance * Low output impedance * Differential to single-ended conversion of the pressure sensor signal * High gain capability 3-318 For this two op-amp circuit, additional modifications to the circuit allow (1) gain adjustment without compromising common mode rejection and (2) both positive and negative dc level shifts of the zero pressure offset. Varying the gain and offset is desirable since full-scale span and zero pressure offset voltages of pressure sensors will vary somewhat from unit to unit. Thus, a variable gain is desirable to fine tune the sensor's full-scale span, and a positive or negative dc level shift (offset adjustment) of the pressure sensor signal is needed to translate the pressure sensor's signal-conditioned output span to a specific level (e.g., within the high and low reference voltages of an A/D converter). For the two op-amp gain stage, this paper will present the derivation of the transfer function and simplified transfer function for pressure sensor applications, the derivation and explanation of the gain stage with a gain adjust feature, and the derivation and explanation of the gain stage with the dc level shift modification. Adding another amplifier stage provides an alternative method of creating a negative dc voltage level shift. This stage is cascaded with the output from the two op-amp stage (Note: gain of the two op-amp stage will be reduced due to additional gain provided by the second amplifier stage). For this three op-amp stage, the derivation of the transfer function, simplified transfer function, and the explanation of the negative dc level shift feature will be presented. GENERAL NOTE ON OFFSET ADJUSTMENT Pressure sensor interface circuits may require either a positive or a negative dc level shift to adjust the zero pressure offset voltage. As described above, if the signal-conditioned pressure sensor voltage is input to an A/D, the sensor's output dynamic range must be positioned within the high and low reference voltages of the A/D; i.e., the zero pressure offset voltage must be greater than (or equal to) the low reference voltage and the full-scale pressure voltage must be less than (or equal to) the high reference voltage (see Figure 1). Otherwise, voltages above the high reference will be digitally converted as 255 decimal (for 8-bit A/D), and voltages below the low reference will be converted as 0. This creates a nonlinearity in the analog-to-digital conversion. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1525 SENSOR'S FULL-SCALE VOLTAGE SPAN FULL-SCALE OUTPUT VOLTAGE ZERO PRESSURE OFFSET VOLTAGE Freescale Semiconductor, Inc... A/D'S OR AMPLIFIER'S DYNAMIC RANGE A/D HIGH REFERENCE OR HIGH SATURATION LEVEL OF AMPLIFIER A/D LOW REFERENCE OR LOW SATURATION LEVEL OF AMPLIFIER Figure 1. Positioning the Sensor's Full-Scale Span within the A/D's or Amplifier's Dynamic Range A similar requirement that warrants the use of a dc level shift is the prevention of the pressure sensor's voltage from extending into the saturation regions of the operational amplifiers. This also would cause a nonlinearity in the sensor output measurements. For example, if an op-amp powered with a single-ended 5 V supply saturates near the low rail of the supply at 0.2 V, a positive dc level shift may be required to position the zero pressure offset voltage at or above 0.2 V. Likewise, if the same op-amp saturates near the high rail of the supply at 4.8 V, a negative dc level shift may be required to position the full-scale pressure voltage at or below 4.8 V. It should be obvious that if the gain of the amplifiers is too large, the span may be too large to be positioned within the 4.6 V window (regardless of ability to level shift dc offset). In such a case, the gain must be decreased to reduce the span. THE TWO OP-AMP GAIN STAGE TRANSFER FUNCTION The transfer function of the two op-amp signal-conditioning stage, shown in Figure 2, can be determined using nodal analysis at nodes 1 and 2. The analysis can be simplified by calculating the transfer function for each of the signals with the other two signals grounded (set to zero), and then employing superposition to realize the overall transfer function. As shown in Figure 2, VIN2 and VIN1 are the differential amplifier input signals (with VIN2 > VIN1), and VREF is the positive dc level adjust point. For a sensor with a small zero pressure offset and operational amplifiers powered from a single-ended supply, it may be necessary to add a positive dc level shift to keep the operational amplifiers from saturating near zero volts. VCC NODE 1 VREF VIN1 R1 R2 R4 NODE 2 U1 VO R3 VO U1 VIN2 Figure 2. The Two Operational-Amplifier Gain Stage Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-319 Freescale Semiconductor, Inc. AN1525 First, the transfer function for VIN1 is determined by grounding VREF and VIN2 at node 1: V IN1 = R1 V O - V IN1 R2 (1) and at node 2: V O R3 =- VO (2) R4 APPLICATION TO PRESSURE SENSOR CIRCUITS The previous section showed the derivation of the general transfer function for the two op-amp signal-conditioning circuit. The simplified form of this transfer function, as applied to a pressure sensor application, is derived in this section. For pressure sensors, VIN1 and VIN2 are referred to as S- and S+, respectively. The simplification is obtained by setting By solving Equations (1) and (2) for VO and equating the results, Equation (3) is established: R2 R1 )1 Freescale Semiconductor, Inc... VO1 = - R 4 R2 R 3 R1 )1 R3 VO = VIN1 (4) R4 R3 )1 VO2 = R3 )1 VIN2 (5) where VO2 represents the part of VO that VIN2 contributes. Finally, to calculate the transfer function between VO and VREF, VIN1 and VIN2 are grounded to obtain the following transfer function: VOREF = R 4R 2 R 3R 1 VREF (6) where VOREF represents the part of VO that VREF contributes. Using superposition for the contributions of VIN1, VIN2, and VREF gives the overall transfer function for the signal- conditioning stage. VO = VO1 + VO2 + VOREF VO = - + R4 R3 R2 R1 R 4R 2 R 3R 1 )1 VREF R4 VIN1 + R3 )1 R2 ( S+ - S-) + VREF (8) G= R4 R3 +1 (9) Also, since the differential voltage between S+ and S- is the pressure sensor's actual differential output voltage (VSENSOR), the following equation is obtained for VO: VO = R4 R3 )1 VSENSOR + VREF (10) Finally, the term VREF is the positive offset voltage added to the amplified sensor output voltage. VREF can only be positive when using a positive single-ended supply. This offset (dc level shift) allows the user to adjust the absolute range that the sensor voltage spans. For example, if the gain established by R4 and R3 creates a span of four volts and this signal swing is superimposed upon a dc level shift (offset) of 0.5 volts, then a signal range from 0.5 V to 4.5 V results. VREF is typically adjusted by a resistor divider as shown in Figure 3. A few design constraints are required when designing the resistor divider to set the voltage at VREF. * To establish a stable positive dc level shift (VREF), VCC should be regulated; otherwise, VREF will vary as VCC varies. VIN2 (7) Equation (7) is the general transfer function for the signal-conditioning stage. However, the general form is not only cumbersome, but also if no care is taken to match certain resistance ratios, poor common mode rejection results. A simplified form of this equation that provides good common mode rejection is shown in the next section. 3-320 R1 By examining Equation (8), the differential gain of the signal- conditioning stage is: where VO1 represents the part of VO that VIN1 contributes. To determine the transfer function for VIN2, VIN1 and VREF are grounded, and a similar analysis is used, yielding R4 = Through this simplification, Equation (7) simplifies to R VIN1 = - 3 VO(3) R4 Solving for VO yields R4 * When "looking" into the resistor divider from R1, the effective resistance of the parallel combination of the resistors, RREF1 and RREF2, should be at least an order of magnitude smaller than R1's resistance. If the resistance of the parallel combination is not small in comparison to R1, R1's value will be significantly affected by the parallel combination's resistance. This effect on R1 will consequently affect the amplifier's gain and reduce the common mode rejection. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1525 without additional constraints on the resistor values. To obtain good common mode rejection, use a similar simplification as before; that is, set VCC R 1 = R4 RREF1 and R 2 = R3 R1 VREF TO U1 Defining the voltage differential between VIN2 and VIN1 as VSENSOR, the simplified transfer function is RREF2 VO = R4 R3 4)1 ) 2R R G (VSENSOR) + VREF (12) Thus, the gain is Freescale Semiconductor, Inc... Figure 3. A Resistor Divider to Create VREF G= THE TWO OP-AMP GAIN STAGE WITH VARIABLE GAIN VREF VIN1 VCC R2 NODE 1 R4 NODE 2 R1 U1 VIN2 VO R3 VO R3 + 2R 4 R +1 (13) G and VREF is the positive dc level shift (offset). Varying the gain of the two op-amp stage is desirable for fine-tuning the sensor's signal-conditioned output span. However, to adjust the gain in the two op-amp gain circuit in Figure 2 and to simultaneously preserve the common mode rejection, two resistors must be adjusted. To adjust the gain, it is more desirable to change one resistor. By adding an additional feedback resistor, RG, the gain can be adjusted with this one resistor while preserving the common mode rejection. Figure 4 shows the two op-amp gain stage with the added resistor, RG. RG R4 U1 Use the following guidelines when determining the value for RG: * By examining the gain equation, RG's resistance should be comparable to R4's resistance. This will allow fine tuning of the gain established by R4 and R3. If RG is too large (e.g., RG approaches ), it will have a negligible effect on the gain. If RG is too small (e.g., RG approaches zero), the RG term will dominate the gain expression, thus prohibiting fine adjustment of the gain established via the ratio of R4 and R3. * Use a potentiometer for RG that has a resistance range on the order of R4 (perhaps with a maximum resistance equal to the value of R4). If a fixed resistor is preferable to a potentiometer, use the potentiometer to adjust the gain, measure the potentiometer's resistance, and replace the potentiometer with the closest 1% resistor value. * To maintain good common mode rejection while varying the gain, RG should be the only resistor that is varied. RG equally modifies both of the resistor ratios which need to be well-matched for good common mode rejection, thus preserving the common mode rejection. Figure 4. Two Operational-Amplifier Gain Stage with Variable Gain THE TWO OP-AMP GAIN STAGE WITH VARIABLE GAIN AND NEGATIVE DC LEVEL SHIFT As with the two op-amp gain stage, nodal analysis and superposition are used to derive the general transfer function for the variable gain stage. The last two op-amp circuits both incorporate positive dc level shift capability. Recall that a positive dc level shift is required to keep the operational amplifiers from saturating near the low rail of the supply or to keep the zero pressure offset above (or equal to) the low reference voltage of an A/D. This two op-amp stage incorporates an additional resistor, ROFF, to provide a negative dc level shift. A negative dc level shift is useful when the zero pressure offset voltage of the sensor is too high. In this case, the user may be required to level shift the zero pressure offset voltage down (toward zero volts). Now, for a specified amount of gain, the full-scale pressure output voltage does not saturate the amplifier at the high rail of the voltage supply, nor is it greater than the A/D's high reference voltage. Figure 5 shows the schematic for this amplifier circuit. VO = - + R4 R3 R4 R3 ) RR4 ) RR2RR4 ) 1 G 3 G R 2R 4 VIN2 ) RR4 ) R R ) RR2RR4 R 2R 4 R 1R 3 G 3 G VREF 1 3 VIN1 (11) This general transfer function also is quite cumbersome and is susceptible to producing poor common mode rejection Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-321 Freescale Semiconductor, Inc. AN1525 VCC ROFF RG R2 NODE 1 NODE 2 R1 VREF VIN1 R4 U1 R3 VO VO U1 VIN2 Freescale Semiconductor, Inc... Figure 5. Two Op-Amp Signal-Conditioning Stage with Variable Gain and Negative Dc Level Shift Adjust To derive the general transfer function, nodal analysis and superposition are used: VO = - + R3 R4 R3 ) RR4 ) RR2RR4 ) 1 R4 G 3 G R 2R 4 ) RR4 ) R R ) RR2RR4 1 3 G R 2R 4 R 1R 3 VIN2 3 G VIN1 R4 VREF + (VIN2 - VCC) R OFF (14) As before, defining the sensor's differential output as VSENSOR, defining VIN2 as S+ for pressure sensor applications, and using the simplification that R 1 = R4 and R 2 = R3 obtains the following simplified transfer function: VO = + R4 R3 4)1 ) 2R R G R4 R (VSENSOR) + VREF S+ - V ROFF = (S+ - VCC) (15) OFF The gain is G= R4 R3 + 2R 4 R +1 (16) G To adjust the gain, refer to the guidelines presented in the section on Two Op-Amp Gain Stage with Variable Gain. VREF is the positive dc level shift, and the negative dc level shift is: V-shift = R4 R (S+ - VCC) (17) OFF The following guidelines will help design the circuitry for the negative dc voltage level shift: 3-322 * To establish a stable negative dc level shift, VCC should be regulated; otherwise, the amount of negative level shift will vary as VCC varies. * ROFF should be the only resistor varied to adjust the negative level shift. Varying R4 will change the gain of the two op-amp circuit and reduce the common mode rejection. * To determine the value of ROFF: 1. Determine the amount of negative dc level shifting required (defined here as V-shift). 2. R4 already should have been determined to set the gain for the desired signal-conditioned sensor output. 3. Although V-shift is dependent on S+, S+ changes only slightly over the entire pressure range. With Motorola's MPX10 powered at a 5 V supply, S+ will have a value of approximately 2.51 V at zero pressure and will increase as high as 2.53 V at full-scale pressure. This error over the full-scale pressure span of the device is negligible when considering that many applications use an 8-bit A/D converter to segment the pressure range. Using an 8-bit A/D, the 20 mV (0.02 V) error corresponds to only 1 bit of error over the entire pressure range (1 bit / 255 bits x 100% = 0.4% error). 4. ROFF is then calculated by the following equation: V CC R 4 -shift (18) An alternative to using this equation is to use a potentiometer for ROFF that has a resistance range on the order of R4 (perhaps 1 to 5 times the value of R4). Use the potentiometer to fine tune the negative dc level shift, while monitoring the zero pressure offset output voltage, VO. As before, if a fixed resistor is preferable, then measure the potentiometer's resistance and replace the potentiometer with the closest 1% resistor value. Important note: The common mode rejection of this amplifier topology will be low and perhaps unacceptable in some applications. (A SPICE model of this amplifier topology showed the common mode rejection to be 28 dB.) However, this circuit is presented as a solution for applications where only two operational amplifiers are available and the common mode rejection is not critical when considering the required www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. First, use the same simplifications as before; that is, set system performance. Adding a third op-amp to the circuit for the negative dc level shifting capability (as shown in the next section) is a solution that provides good common mode rejection, but at the expense of adding an additional op-amp. R 1 = R4 and THE THREE OP-AMP GAIN STAGE FOR NEGATIVE DC LEVEL SHIFTING VO = * Its non-inverting configuration provides gain via the ratio of R6 and R5. Freescale Semiconductor, Inc... * It has negative dc voltage level shifting capability typically created by a resistor divider at V-shift, as discussed in the section on Application to Pressure Sensor Circuits. Although this configuration requires a third op-amp for the negative dc level shift, it has no intrinsic error nor low common mode rejection associated with the negative level shift (as does the previous two op-amp stage). Depending on the application's accuracy requirement, this may be a more desirable configuration for providing the negative dc level shift. 1 ) RR6 R4 R3 5 + VREF 4)1 ) 2R R G R6 - V R 5 -shift V ) RR6 5 R4 R3 (20) The gain is G= 1 SENSOR 4)1 ) 2R R G (21) VREF is the positive dc level shift (offset), and V-shift is the negative dc level shift. VCC RG R5 V-SHIFT R2 VREF VIN1 R 2 = R3 Defining the voltage differential between VIN2 and VIN1 as VSENSOR , the simplified transfer function is This circuit adds a third op-amp to the output of the two op-amp gain block (see Figure 6). This op-amp has a dual function in the overall amplifier circuit: R1 AN1525 R6 R4 U1 U1 R3 VO VIN2 VO U1 VO Figure 6. Three Op-Amp Gain Stage with Variable Gain and Negative Dc Level Shift The transfer function for this stage will be similar to the chosen two op-amp gain stage configuration (either the fixed gain with positive dc level shift circuit or the variable gain with positive dc level shift circuit) with additional terms for the negative level shift and gain. As an example, the variable-gain two op-amp gain circuit is used here. All of the design considerations and explanations for the variable gain two op-amp circuit apply. The transfer function may be derived with nodal analysis and superposition. VO = 1 - + )R R4 R3 R6 R4 5 R3 )R )R R )1 R4 R 2R 4 G 3 G ) RR4 ) RR2RR4 ) RR2RR4 R 2R 4 R 1R 3 3 G G V REF - R6 R5 Motorola Sensor Device Data 1 3 V-shift The preceding simplifications have been performed in the previous sections, but by examining Equation 20, notice that the third op-amp's gain term also amplifies the positive and negative dc voltage level shifts, VREF and V-shift. If R6 and R5 are chosen to make an arbitrary contribution to the overall system gain, designing an appropriate amount of positive and negative dc level shift can be difficult. To simplify the transfer function, set R5 = R6, and the following equation for VO results: VO = 2 VIN2 VIN1 R4 R3 4)1 ) 2R R - V -shift (19) G V SENSOR ) V REF (22) Now the third op-amp's contribution to the overall system gain is a factor of two. When designing the overall system gain and the positive dc level shift, use the following guidelines: www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-323 Freescale Semiconductor, Inc. AN1525 * Since the third op-amp contributes a gain of two to the overall system, design the gain that the two op-amp circuit contributes to the system to be one-half the desired system gain. The gain term for the two op-amp circuit is: G= R4 R3 + 2R 4 RG +1 which is the same as presented in Equation 16. Freescale Semiconductor, Inc... * Similarly, since the third op-amp also amplifies VREF by two (refer to Equation 22), the resistor divider that creates VREF should be designed to provide one-half the desired positive dc voltage level shift needed for the final output. When designing the voltage divider for VREF, use the same design constraints as were given in the section on Application to Pressure Sensor Circuits. With the above simplification of R5 = R6, the negative dc level shift, V-shift, which is also created by a voltage divider, is now amplified by a factor of unity. When designing the voltage divider, use the same design constraints as were presented in the section on Application to Pressure Sensor Circuits. 3-324 CONCLUSION The amplifier circuits discussed in this paper apply to pressure sensor applications, but the amplifier circuits can be interfaced to low-level, differential-voltage output sensors, in general. All of the circuits exhibit the desired instrumentation amplifier characteristics of high input impedance, low output impedance, high gain capability, and differential to single-ended conversion of the sensor signal. Each amplifier circuit provides positive dc level shift capability, while the last two circuit topologies presented are also able to provide a negative dc voltage level shift. This enables the user to position the sensor's dynamic output within a specified range (e.g., within the high and low references of an A/D converter). Also detailed is a method of using an additional feedback resistor to adjust easily the differential voltage gain, while not sacrificing common mode rejection. Combining the appropriate sensor device and amplifier interface circuit provides sensor users with a versatile system solution for applications in which the ideal fully single-conditioned sensor does not exist or in which such signal flexibility is warranted. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1536 Digital Boat Speedometers Prepared by: Bill Lucas Industrial Technology Center Freescale Semiconductor, Inc... INTRODUCTION This application note describes a Digital Boat Speedometer concept which uses a monolithic, temperature compensated silicon pressure sensor, analog signal-conditioning circuitry, microcontroller hardware/software and a liquid crystal display. This sensing system converts water head pressure to boat speed. This speedometer design using a 30 psi pressure sensor (Motorola P/N: MPXM2202GS) yields a speed range of 5 mph to 45 mph. Calibration of the system is performed using data programmed into the microcontroller's internal memory. A key advantage in all Motorola pressure sensors is the patented X-ducer, a single piezoresistive implant that replaces the traditional Wheatstone bridge configuration used by competitors. In addition to the X-ducer, Motorola integrates on-chip all necessary temperature compensation, eliminating the need for separate substrates/hybrids. This state-of- the-art technology yields superior performance and reliability. Motorola pressure sensors are offered in several different port configurations to allow measurement of absolute, differential and gauge pressure. Motorola offers three pressure sensor types: uncompensated, temperature compensated and calibrated or fully signal conditioned. WATER PRESSURE TO BOAT SPEED CONVERSION A typical analog boat speedometer employs a pitot tube, a calibrated pressure gauge/speedometer and a hose to connect the two. The pitot tube, located at the boat transom, provides the pressure signal corresponding to boat speed. This pressure signal is transmitted to the gauge via the hose. Boat speed is related to the water pressure at the pitot tube as described by the following equation: P T e * (V22g) where: V P e g = = = = speed pressure at pitot tube specific weight of media gravitational acceleration Motorola Sensor Device Data For example, to calculate P in lb/in2 for an ocean application use: V = speed in mph e = 63.99 lbs/ft3 at 60F, seawater (e will be smaller for fresh water) g = 32 ft/sec2 15 mph = 22 ft/sec 1 ft2 = 144 in2 P + (63.99[lbft3] 144[in2ft2]) (V2[mph]2 (2215)2[(ftsec)mph]2 2 (32.2)[ftsec2]) + V 2 8.208 For example, if the boat is cruising at 30 mph, the impact pressure on the pitot tube is: P[PSI] P + (308.208)2 + 13.36 psi. DIGITAL BOAT SPEEDOMETER DESCRIPTION AND OPERATION The MPXM2202GS senses the impact water pressure against the pitot tube and outputs a proportional differential voltage signal. This differential voltage signal is then fed (via an analog switch and gain circuitry) to a single slope analog-to-digital converter (A/D) which is external to the microcontroller. The A/D circuit can complete two separate conversions as well as a reference conversion simultaneously. This A/D utilizes the microcontroller's internal timers as counters and software to properly manipulate the data. The analog switch provides a way to flip the sensor outputs after an A/D conversion step, which is necessary to null out the offset effects of the op-amps. This is accomplished by performing an analog conversion, reversing the sensor's differential output signal, performing another analog conversion, summing the two readings, then dividing this sum by two. Any op-amp offset present will be the same polarity regardless of the sensor output polarity, thus the op-amp offset can be mathematically nulled out. The digital representation of any analog signal is ratiometric to the reference voltages of the A/D converter. Also, the sensor's output is ratiometric to its excitation voltage. Therefore, if both the sensor and A/D reference voltages are connected to the same unregulated supply, the variations in sensor output will be nullified, and system accuracy will be maintained (i.e., systems in which both the A/D converter's digital value -- due to variations in the A/D's reference voltages -- and sensor's output voltage are ratiometric to the supply voltage so that a voltage regulator is not necessary). www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-325 Freescale Semiconductor, Inc. AN1536 Again, because any op-amp offset will remain the same polarity regardless of sensor output polarity, this routine will effectively cancel any amplifier offset. Any offset the sensor may introduce is compensated for by software routines that are invoked when the initial system calibration is done. The single slope A/D provides 11 or more unsigned bits of resolution. This capability provides a water pressure resolution to at least 0.05 psi. This translates to a boat speed resolution of 0.1 mph over the entire speed range. Figure 2 describes the pressure versus voltage transfer function of the first op-amp stage. Figure 1 shows the pressure sensor (XDCR) connected to the analog switches of the 74HC4053 which feeds the differential signal to the first stage of op-amps. An A/D conversion is performed on the two op-amp output signals, Vout1 and Vout2. The difference (Vout1 - Vout2) is computed and stored in microcontroller memory. The analog switch commutates (op-amp connections switch from Y0 and Z0 to Y1 and Z1), reversing the sensor output signals to the two op-amps, and another conversion is performed. This value is then also stored in the microcontroller memory. To summarize, via software, the following computation takes place: Step 1: Vfirst = Vout1 - Vout2 Step 2: Vsecond = Vout2 - Vout1 Step 3: Vresult = (Vfirst + Vsecond) / 2 Freescale Semiconductor, Inc... +5 6 MPXM2202GS 7 2 Y0 +8 8 16 +8 74HC4053 8 + 33078 7 6 - 22 pF 15 1 5 Y1 3 2 + VOUT1 10 k 316 k 10 k - 4 316 k 1 22 pF - 1 33078 3 + 4 2 5 Z0 4 3 Z1 DENOTES ANALOG GROUND VOUT2 10 k 11 12 13 9 10 DENOTES LOGIC GROUND XDCR INPUT REVERSE CONTROL Figure 1. X-ducer, Instrument Amplifier and Analog Switch 8 6 VOLTS OUT U3-1 (U3-7) 4 2 U3-7 (U3-1) 0 0 10 20 PRESSURE IN 30 PSI Figure 2. Instrument Amplifier Transfer Function 3-326 Figure 3 details the analog circuitry, microcontroller's timer capture registers and I/O port which comprise the single slope A/D. The microcontroller's 16-bit free running counter is also employed, but not shown in the figure. Comparators U6A, U6B and U6D of the LM139A are used to provide the A/D function. Constant current source, U7, resistors R13 and R14 and diode D2 provide a linear voltage ramp to the inverting inputs of U6, with about 470 microamps charge current to capacitor C8, with transistor Q1 in the off state. C8 will charge to 5 volts in about 5 milliseconds at the given current. Q1 is turned on to provide a discharge path for C8 when required. The circuit is designed such that when the voltage to the inverting inputs of the comparators exceeds the voltage to the noninverting comparators, each comparator output will trip from a logic 1 to a logic 0. One A/D conversion consists of the following steps: (1) setting the pressure sensor output polarity (via software and the analog switches of U4) to the amplifier inputs of the MC33078 (U3), (2) reading the value of the free running www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. The boat speed display for this design employs an MC145453 LCD driver and four-digit liquid crystal display, of which three digits and a decimal point are used. Figure 4 shows the connections between the display driver and the display. The display driver is connected to the microprocessor's serial peripheral interface (SPI). The software necessary to initialize, format and drive the LCD is included in the software listing contained in this article. counter, (3) turning off Q1, and (4) charging C8 and waiting for the three (U6) comparator outputs to change from 1 to 0. When the comparator outputs change state, the microcontroller free running counter value is clocked into the microcontroller's input capture register. Contained in this register then is the number of counts required to charge C8 to a value large enough to trip the comparators. Via software, the voltage signal from U3 (corresponding to the applied pressure signal) can be compared to the "reference." LM334Z-3 U7 Freescale Semiconductor, Inc... +8 +8 3 POLYCARBONATE D2 (APPROX. 470 A) 1N914 R13 147 R14 1.5 k 5% 2N7000 C8 0.47 F R12 4.7 5% AN1536 1/4 U6C - LM139A 11 13 + 10 32 IC1 (PA2) INPUT CAPTURE REGISTER 1 R11 10 k 5% VREF (APPROX. 4.5 V) +5 MC68HC711E9 Q1 27 1/4 U6B - LM139A 9 14 + 12 PA7 GENERAL PURPOSE OUTPUT 8 FROM U3-7 33 IC2 (PA1) INPUT CAPTURE REGISTER 2 IC3 (PA0) INPUT CAPTURE REGISTER 3 R10 10 k 5% +5 1/4 U6A - LM139A 5 2 + 4 FROM U3-1 R9 10 k 5% 34 Figure 3. Analog-to-Digital Converter Front End with Microcontroller Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-327 NC 3-328 19 26 18 17 16 37 36 5 15 6 34 35 14 13 11 7 10 8 9 8 7 31 32 9 6 10 5 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 43 42 41 26 27 13 24 VSS C2 0.1 CLOCK 25 MC145453FN 44 DATA BIT 3 12 40 14 39 15 4 GND +5 DATA 2 3 CLOCK 36 16 1 38 37 24 25 IEE PART NUMBER LCD5657 OR EQUAL DATA 4 29 30 VDD U1 11 LIQUID CRYSTAL DISPLAY LCD Freescale Semiconductor, Inc... 35 33 32 22 23 17 31 18 30 19 29 28 20 21 VSS 2 OSC 21 IN 27 26 22 IN OUT VCC 1 BP C1 470 pF R1 470 k +5 AN1536 Freescale Semiconductor, Inc. Figure 4. Boat Speedometer Display Board Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Table 1 lists the jumper wire selections needed for calibration and operational modes. The jumper wire junction block (J1, J2, J3) is connected to the microprocessor, pins PC0, PC1 and PC2, respectively as shown in Figure 5. +8 Table 1. J1 J2 J3 OUT OUT OUT OUT OUT IN 100 psi X-ducer installed OUT IN OUT 30 psi X-ducer installed OUT IN IN 15 psi X-ducer installed IN OUT OUT IN OUT IN IN IN OUT Display pressure in psi IN IN IN Display speed in mph +8 POLYCARBONATE LM334Z-3 3 D2 (APPROX. 470 A) U7 10 - 1/4 U6 LM139A C8 11 13 + 0.47 F R13 147 2N7000 32 3 2 U4 4 8 9 4 Z1 11 12 13 9 10 R5 316 k 1/4 U6 - LM139A 7 + D1 MC78L05 ACP U2 R1 4.7 5% 6 1N4004 C1 0.1 + C2 33 F 33 34 42 52 47 49 MC78L08 ACP U1 IRQ C3 0.1 + C4 10 F C5 0.1 +8 44 R2 1.15 k VREF (APPROX. 4.5 V) 46 R3 1.5 k 50 48 2 19 VDD 26 R15 IC3 (PA0) PE1 PB0 VRH VRL +5 + C7 10 F MC34064 P-5 U8 XIRQ 18 PC2 PC1 R4 10 k 5% 17 +5 MODB R9 10 k 5% 51 C6 0.1 RESET R18 4.7 k 5% IC2 (PA1) R10 10 k 5% 45 VREF + 12 GND 1/4 U6 - LM139A 5 2 + C13 22 pF - 2 33078 3 + 1/2 U3 4 PE0 +5 R7 316 k 6 5 - LM139A 14 + R8 10 k 5% 1 3 Y1 8 MHz +5 PA7 1/4 U6 4 5 Z0 8 C12 22 pF MC68HC711E9FN +8 8 R6 10 k 7 U5 1/2 U3 + 7 33078 6 C14 22 pF - 1 Y1 XTAL R19 10 MEG 5% Q1 43 15 5 +8 Zero calibrate EXTAL +5 MPXM2202GS Full scale calibrate R11 10 k 5% 27 6 7 8 16 74HC4053 2 Y0 Display speed in mph IC1 (PA2) VREF +5 R12 4.7 5% R14 1.5 k 5% AN1536 PE2 PE3 PE4 PE5 PE6 PE7 PC0 R16 11* J3 10 J2 9 J1 1 VSS 31 PA3 3 MODA 20 PD0 21 PD1 22 PD2 25 PD5 4 STRA (PD4) SCK (PD3) MOSI R17 3-10 k 5% 24 23 +5 C10 0.1 TEST JUMPERS 1 2 3 4 NOTES: UNLESS OTHERWISE NOTED, ALL RESISTORS 1% METAL FILM. * U5 PINS 11-16 (PC2-PC7) ARE CONNECTED HERE FOR * TERMINATION PURPOSES. Figure 5. Boat Speedometer Processor Board Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-329 AN1536 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... The calibration of this system is as follows. Refer to Table 1. CAUTION: While installing or changing the proper jumpers described by each step, power must be off. Reapply power to read the display after jumpers have been installed in their proper location for each step. In each step there is a few seconds' delay after switching the power on and before an output is displayed. Steps 1 through 3 must be performed prior to system being operational. Calibration 1. The pressure range of the system must be established. The present software installed in this design supports 15, 30 and 100 psi sensors. Using an MPXM2202GS sensor (30 psi) for example, only jumper J2 should be installed. After power is applied, the LCD should read "30." Power off the system prior to proceeding to step 2. 2. The total system offset, due to the sensor and A/D, must be established for the software routine to effectively calibrate. With power off, jumpers J1 and J3 should be installed. Reapply power, and the LCD should respond 3-330 with "000." The offset value measured in this step is thus stored for use in circuit operation. Power off the system prior to proceeding to step 3. 3. In this step, the system full scale span is calibrated. With power off, install jumper J1 only. Now apply the full rated pressure (30 psi for MPXM2202GS) to the sensor, power on and ensure the display reads "FFF." The full scale span measured in this step is thus stored for use in circuit operation. Power off the system prior to step 4. Operation 4. Ensure power is off, and install jumpers J1, J2 and J3. The system is now ready for operation. Simply apply power and pressure to the sensor, and the LCD will display the proportional speed above 5 mph, up to the limits of the sensor. REFERENCES Burry, Michael (1989). "Calibration-Free Pressure Sensor System," Motorola Application Note AN1097. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1536 NOTE. THIS WAS COMPILED WITH A COMPILER COURTESY OF: INTROL CORP. 9220 W. HOWARD AVE. MILWAUKEE, WI. 53228 PHONE (414) 327-7734. SOME SOURCE CODE CHANGES MAY BE NECESSARY FOR COMPILATION WITH OTHER COMPILERS. THE HEADER FILE io6811.h HAS I/O PORT DEFINITIONS FOR THE I/O PORTS PARTICULAR TO THE MC68HC711E9. A TYPICAL ENTRY FOR PORT A WILL FOLLOW. THE FIRST LINE ESTABLISHES A BASE ADDRESS BY WHICH ALL I/O FACILITIES AND COUNTERS ARE BIASED. REFER TO THE MC68HC711E9 DATA FOR MORE INFORMATION RELATIVE TO I/O AND TIMER ADDRESSES. #define IOBIAS 0x1000 /* BASE ADDRESS OF THE I/O FOR THE 68HC11 */ #define PORTA (* (char *) (IOBIAS + 0)) /* PORT A */ THE STARTUP ROUTINE NEED ONLY LOAD THE STACK TO THE TOP OF RAM, ZERO THE MICROCONTROLLER'S RAM AND PERFORM A BSR MAIN (BRANCH TO SUBROUTINE "MAIN"). THIS SOURCE CODE, HEADER FILE, COMPILED OBJECT CODE, AND LISTING FILES ARE AVAILABLE ON: THE MOTOROLA FREEWARE LINE AUSTIN, TX. (512) 891-3733. Freescale Semiconductor, Inc... Bill Lucas 6/21/90 THE CODE STARTS HERE #include <io6811.h> */ /* I/O port definitions */ /* define locations in the eeprom to store calibration information */ #define EEPROM (char*)0xb600 /* used by calibration functions */ #define EEBASE 0xb600 /* start address of the eeprom */ #define ADZERO (* ( long int *)( EEBASE + 0 )) /* auto zero value */ #define HIATOD (* ( long int *)( EEBASE + 4 )) /* full scale measured input */ #define XDCRMAX (* ( char *)( EEBASE + 8 )) /* full scale input of the xdcr */ union bytes { unsigned long int l; char b[4]; }; /* ADZERO.l for long word ADZERO.b[0]; for byte */ const char lcdtab[] = { 95, /* lcd pattern table 0 6, 1 59, 2 47, 102, 109, 125, 7, 127, 111, 0 }; 3 4 5 6 7 8 9 blank */ const int dectable[] = { 10000, 1000, 100, 10 }; char digit[5]; /* buffer to hold results from cvt_bin_dec function */ /* ################################################################### */ /* real time interrupt service routine */ void real_time_interrupt (void) /* hits every 4.096 ms. */ { TFLG2 = 0x40; /* clear the interrupt flag */ } /* ################################################################### */ /* ################################################################### */ /* write_eeprom(0xA5,EEPROM); write A5h to first byte of EEPROM */ void write_eeprom(char data, char *address) { PPROG = 0x16; /* single-byte erase mode */ *address = 0xff; /* write anything */ PPROG = 0x17; /* turn on programming voltage */ delay(); PPROG = 0x0; /* erase complete */ /* now program the data */ PPROG = 0x02; /* set eelat bit */ *address = data; /* write data */ PPROG = 0x03; /* set eelat and eepgm bits */ delay(); PPROG = 0; /* read mode */ /* programming complete */ } /* ################################################################### */ long int convert(char polarity) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-331 Freescale Semiconductor, Inc. AN1536 { unsigned unsigned unsigned unsigned unsigned int cntr; /* free running timer system counter */ int r0; /* difference between cntr and input capture int r1; /* difference between cntr and input capture int r2; /* difference between cntr and input capture long difference; /* the difference between the upper and instrument amplifier outputs */ unsigned long int pfs; /* result defined as percent of full scale the reference voltage */ if (polarity == 1) PORTB &= 0xfe; else PORTB |= 0x1; Freescale Semiconductor, Inc... delay(); 1 register */ 2 register */ 3 register */ lower relative to /* set the hc4053 configuration */ /* polarity = 1 means + output of sensor */ /* is connected to the upper opamp */ /* this will allow the hc4053 to stabilize and the cap to discharge from the previous conversion */ TFLG1=0X07; /* clear the input capture flags */ cntr=TCNT; /* get the current count */ PORTA &= 0X7F; /* turn the fet off */ while ((TFLG1 & 0X7) < 7); /* loop until all three input capture flags are set */ r0 = TIC1 - cntr; /* reference voltage */ r1 = TIC2 - cntr; /* top side of the inst. amp */ r2 = TIC3 - cntr; /* lower side of the inst. amp */ PORTA |= 0X80; /* turn the fet on */ if (polarity == 1) difference = ( r1 + 1000 ) - r2; else difference = ( r2 + 1000 ) - r1; pfs = (difference * 10000) / r0; if (difference > 32767) /* this will cover up the case where the a to d computes a negative value */ pfs=0; return ( pfs ); } atod() /* computes the a/d value in terms of % full scale */ { unsigned long int x,y,z; x = convert(1); /* normal */ y = convert(0); /* reversed */ z = (x + y)>>1 ; /* 2x difference / 2 */ return(z); /* z is percent of full scale */ } integrate() /* returns the a/d value in terms of % full scale and computes offset from calibration values */ { unsigned long int j; int i; j=0; for (i=0; i<20; ++i) j +=atod(); j = (j/20) - ADZERO; /* null out the xdcr zero input offset */ return(j); } cala2d() /* returns the average of 50 raw a/d conversions this is only used by the calibration functions */ { unsigned long int j; int i; j=0; for (i=0; i<50; ++i) { j +=atod(); } j=j/50; return(j); } /* ################################################################### */ cvt_bin_dec ( unsigned int arg ) { char i; for ( i=0; i < 6; ++i ) 3-332 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1536 { digit[i] = 0; /* put blanks in all digit positions */ } for ( i=0; i < 4; ++i ) { if ( arg >= dectable [i] ) { digit[i] = arg /dectable[i]; arg = arg-(digit[i] * dectable[i]); } } digit[i] = arg; } /* ################################################################### */ Freescale Semiconductor, Inc... delay() { int i; for (i=0; i<1000; ++i); /* delay about 15 ms. @ 8 mhz xtal */ } /* ################################################################### */ /* set-up i/o for the single slope a/d, initialize the spi port, then initialize the MC145453 for output */ init_io(void) { char i; /* set-up i/o for the a/d */ PACTL |= 0X80; /* make pa7 an output */ PORTA |= 0X80; /* turn the fet on */ PORTB &= 0X7F; /* set-up the HC4053 in the Y0/Z0 connect mode */ TCTL2 = 0X2A; /* capture on falling edge for timer capture 0,1,2 */ TFLG1 = 0X07; /* clear any pending capture flags */ /* set-up the i/o for the spi subsystem */ PORTD=0x2f; /* set output low before setting the direction register */ DDRD=0x38; /* ss = 1, sck = 1, mosi = 1 */ SPCR=0x51; /* enable spi, make the cpu the master, E clock /4 */ /* initialize the lcd driver */ for (i=0; i<4; ++i) /* four bytes of zeros */ { write_spi(0); } write_spi (2); /* this creates a start bit and data bit 1 for the next write to the mc145453 */ } /* ################################################################### */ /* this is an attempt at the newton square root method */ sqrt(unsigned long b) { unsigned long x0,x1; if ( b < 4 ) { b=2; return (b); } else x0=4; x1=10; while (x0 != x1) { if( (x1-x0) ==1 ) break; x1=x0; x0=(( (b/x0) +x0 ) >> 1 ); } b=x0; return (b); } /* ################################################################### */ Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-333 Freescale Semiconductor, Inc. AN1536 write() { char i; digit[1]=10; if (digit[2]==0) {digit[2]=10;} if ( digit[2]==10 && digit[3]==0 ) {digit[3]=10;} for ( i=1; i<5; ++i ) { if (i==4) write_spi((lcdtab[digit[i]])+0x80); else write_spi(lcdtab[digit[i]]); } write_spi (2); /* this creates a start bit and data bit 1 for the next write to the mc145453 */ } Freescale Semiconductor, Inc... write_spi( char a ) /* write a character to the spi port */ { SPDR=a; while ( ! ( SPSR & 0x80 ) ) {} /* loop until the spif = 1 */ } /* ################################################################### */ /* This function is called at power-up and will determine the operation of the system. The user must complete the system configuration prior to setting the jumper in the first or last two configurations in the table or erroneous operation is guaranteed! test/operation jumper configuration: J3 J2 J1 1 = jumper removed 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 display speed in mph reserved 30 psi xdcr installed 15 psi xdcr installed full scale calibrate zero calibrate display pressure in psi display speed in mph */ setconfig() { char i; for ( i=0; i<125; ++i ) delay(); /* to let the charge pump come to life wll */ i = PORTC & 0x07; /* and off the unused bits */ if ( i == 7 ) display_speed(); if ( i == 6 ) setup_error(); /* non-valid pattern output -SE- on display*/ if ( i == 5 ) {write_eeprom(30,&XDCRMAX); /* xdcr is 30 psi */ display(30); } if ( i == 4 ) {write_eeprom(15,&XDCRMAX); /* xdcr is 15 psi */ display(15); } if ( i == 3 ) fullscale_calibrate(); if ( i == 2 ) zero_calibrate(); if ( i == 1 ) display_pressure(); else display_speed(); } /* ################################################################### */ display(char d) 3-334 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. { if (d==30) { write_spi(0); write_spi(0); write_spi(47); write_spi(95); } if (d==15) { write_spi(0); write_spi(0); write_spi(6); write_spi(109); } /* /* /* /* blank the upper digit */ blank the next to upper digit */ 3 */ 0 */ /* /* /* /* blank the upper digit */ blank the next to upper digit */ 1 */ 5 */ AN1536 write_spi(2); while(1); } Freescale Semiconductor, Inc... /* ################################################################### */ fullscale_calibrate() { int i; long int temp; union bytes average; temp=0; average.l = cala2d(); /* get the average of 50 a/d conversions */ for ( i=0; i<4; ++i) write_eeprom(average.b[i],EEPROM+i+4); write_spi(0); write_spi(113); write_spi(113); write_spi(113); write_spi(2); while(1); /* /* /* /* blank the upper digit */ F */ F */ F */ } /* ################################################################### */ zero_calibrate() { int i; long int temp; union bytes average; temp=0; average.l = cala2d(); /* get the average of 50 a/d conversions */ for ( i=0; i<4; ++i) write_eeprom(average.b[i],EEPROM+i); write_spi(0); write_spi(95); write_spi(95); write_spi(95); write_spi(2); while(1); } /* /* /* /* blank the upper digit */ 0 */ 0 */ 0 */ /* ################################################################### */ /* speed=8.208(square root(%full scale*transducer full scale)) */ display_speed() { long atod_result; unsigned int j; while(1) { atod_result = integrate(); /* read the a/d */ atod_result=( (atod_result*10000) / (HIATOD-ADZERO) ) * XDCRMAX; atod_result=sqrt(atod_result); atod_result=(atod_result*8208)/10000; j=atod_result; Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-335 Freescale Semiconductor, Inc. AN1536 if (j<50) { j=0; } cvt_bin_dec ( j ); write(); } } /* ################################################################### */ Freescale Semiconductor, Inc... /* pressure=%full scale*transducer max pressure */ display_pressure() { long atod_result; int j; while(1) { atod_result = integrate(); /* read the a/d */ atod_result=( (atod_result*1000) / (HIATOD-ADZERO) ) * XDCRMAX; j=atod_result/100; cvt_bin_dec ( j ); write(); } } /* ################################################################### */ setup_error() /* write "SE" on the display */ { write_spi(0); write_spi(109); /* S */ write_spi(121); /* E */ write_spi(0); write_spi(2); while(1); } /* ################################################################### */ main() { init_io(); setconfig(); /* determine how to function */ while(1); /* should never return here except after calibration */ } 3-336 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Low-Pressure Sensing with the MPX2010 Pressure Sensor AN1551 Prepared by: Jeffery Baum Systems Engineering Group Leader Sensor Products Division Motorola Semiconductor Products Sector Phoenix, AZ Freescale Semiconductor, Inc... INTRODUCTION Until recently, low-cost semiconductor pressure sensors were designed to measure typical full-scale pressures only as low as 10 kPa (1.5 psi). Of course, "measure" is a relative term. "Measure" is used here to imply that an output of reasonable magnitude, signal-to-noise ratio, and accuracy is produced by the sensing device. Such sensor products are available in various levels of integration and package types. Depending on the level of application customization required and the budget available, a sensor user may choose from a range of low-pressure sensor products such as a 10 kPa "bare-element" (uncompensated) device, a 10 kPa calibrated and temperature compensated device, or a fully signal-conditioned (high-level output), calibrated, and temperature compensated integrated 10 kPa device. These options are typically available as well for higher pressures ranging up to 1000 kPa. What if the sensor user must measure full-scale pressures that are two, four, or even ten times lower than what conventional sensor technology is capable of measuring? "Do such applications and customers exist?'' The answer is "yes" and "yes." There are many potential customers that require such low-pressure sensing ability, the two application examples discussed here are: (1) heating ventilation and air-conditioning (HVAC) in the context of building controls and (2) water-level sensing in appliance applications such as clothes washing machines. For the purposes of measuring low pressures, the units of inches of water ( H2O) or millimeters of water (mm H2O) will be used. Typical HVAC applications have a full-scale pressure of 40 mm H2O and washing machines have either 300 or 600 mm H2O, depending on the region of the world (Note: just for reference purposes, 10 kPa 40 H2O 1000 mm H2O 1.5 psi). Of course, a sensor intended for a higher pressure range than the one of interest can be used. However, the effect is that only a small portion on the device's dynamic output range is used for the actual operating range. This low-level output may then be paired up with a larger than ideal amplifier gain. Thus, a poor signal-to-noise ratio is usually the result. Some sensor manufacturers have recently introduced pressure sensors designed for 4 and 5 H2O full-scale ranges (approx. 100-125 mm H2O). These devices typically employ silicon with very thinly micromachined diaphragms or other sensing technologies that are significantly larger in form factor without any additional functionality. Thin diaphragm devices tend to be extremely fragile and unstable. Even in cases where the device is sufficiently robust for the intended operating [ Motorola Sensor Device Data [ [ pressure range, the sensor has very poor overpressure capability. Now that the pressure range of interest has been established, the stage has been set to consider the system solution that is the enabling technology for achieving such low-pressure sensing capability. Also important in presenting this low-pressure system solution are some of the other application characteristics besides the pressure range. For example, the desired pressure resolution, accuracy, available power supply voltage, and end-equipment system architecture play a major role in determining the implementation of this system solution. DEVELOPMENT HISTORY For simplicity's sake, let's refer to this low-pressure sensing system solution as the "smart sensing" or "smart sensor system." One of the key performance advantages of the smart sensor system is that the output of the actual sensing element is ratiometric (linearly proportional) to the excitation voltage applied to the sensing element. Since most semiconductor pressure sensors are characterized with a constant voltage power supply, current excitation will not be discussed. Although a sensor's operation is specified at a given power supply voltage, there is some maximum supply that can be applied, beyond which power dissipation and self-heating produce significant output errors or exceed the package's thermal handling capability. This means that the strategy of increasing the sensor's excitation to improve the sensor's sensitivity (increase signal output for a given applied pressure) can be done in a dc fashion only up to some maximum supply voltage. For Motorola pressure sensors, this limit allows only about a 50% to 60% increase in sensitivity, depending on the specific device family. About five years ago, some of my colleagues were working on pulsing the sensor supply voltage with a conventional voltage and very low duty-cycle, sampling-and-holding the resulting output, and then filtering the output to produce a dc sensor output with very low-power consumption. This was the impetus to consider pulsing a sensor at a much higher than recommended voltage and a low duty-cycle (10% or less) for the purpose of increased sensitivity. It is true that some of the sensor's parasitic drawbacks, like its zero-pressure offset voltage and temperature coefficient of offset, are increased as well, but some of the sensor's negative characteristics are lessened. In addition, other sources of error and noise in the system are not subjected to the higher amplifier gain that would be required if operating the sensor at a conventional supply voltage. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-337 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1551 The Motorola MPX2010 (see Table 1) is a calibrated and temperature compensated, 10 kPa (full-scale), pressure sensor device. The data sheet specifies a full-scale output of 25 mV at a 10 V supply voltage, for an applied pressure of 10 kPa. This same device can be pulsed at 40 V at a 10% duty-cycle and produce either 100 mV for the same 10 kPa pressure or 25 mV for only 2.5 kPa of pressure. This technique allows a four-fold increase in the signal level for the rated full-scale pressure of 10 kPa or the ability to maintain the same signal level for a pressure that is four times lower (2.5 kPa). Although the idea is relatively simple, the key to providing a low-cost smart sensing solution is in both the hardware and software implementation of this system. In the case of the micropower application, having a "stand-alone" analog sensing solution was a key criteria. As such, this design used micropower op-amps, analog CMOS switches, gated timers (one to control pulsed sensor excitation and one to control sample-and-hold function), and capacitive sample-and-hold circuitry. The effect was a very low-current drain, micropower sensor solution. Since low-power, rather than low-pressure, was the driving design goal, errors induced by power supply variation, temperature drift, and device-to-device tolerances were not critical. Not that these issues are not important for all applications, but for low-pressure sensing, even small temperature drifts, device parameter tolerances, and power supply variations cause significant errors as a percentage of the sensor output signal. It should be apparent that the "gated-timer pulsing/sample-and-hold" system architecture can be equally well employed to pulse at higher voltages for increased sensitivity. However, a low-cost MCU can also accomplish the functions of providing a control pulse to a switching circuit (for the pulsed sensor excitation) and affecting a synchronized sample-and-hold feature via software control of an on-chip A/D converter. In addition, the MCU has the capability to implement other "smart" features that can lend the additional required accuracy and functionality desired for many low-pressure sensing applications. The system design intended for low-pressure applications, as well as the performance-enhancing features of pulsed excitation for increased sensitivity, signal averaging, software calibration, and software power supply rejection are presented. The added functionality of intelligent communications capability and serial digital output flexibility are also discussed. Of course, these features lead to increased performance at conventional, or even high-pressure ranges. Nonetheless, these features have been developed in the context of low-pressure sensing where the performance benefits are a requisite of the application. Also, driving acceptance of this system technology is a much easier task when coupled to providing a sensing capability and level of functionality that is otherwise not available in the industry today. Who would have suspected that a viable smart sensing technology would have resulted from the pursuit of addressing the low-pressure sensing market? Significant pieces of this system solution are protected intellectual property. Motorola holds several key patents on using pulsed excitation for semiconductor sensors and has filed several others regarding other portions and future enhancements to this technology. Table 1. MPX2010 Operating Characteristics (Supply Voltage = 10 Vdc, TA = 25C unless otherwise noted) Characteristic Min Typ Max Unit Pressure Range 0 -- 10 kPa Supply Voltage -- 10 16 Vdc Supply Current -- 6.0 -- mAdc Full Scale Span (FSS) 24 25 26 mV Zero-Pressure Offset -1.0 -- 1.0 mV -- 2.5 -- mV/kPa -1.0 -- 1.0 %VFSS Pressure Hysteresis (0 to 10 kPa) -- 0.1 -- %VFSS Temperature Hysteresis (- 40C to +125C) -- 0.5 -- %VFSS -1.0 -- 1.0 %VFSS Temperature Effect on Offset (0C to 85C) -1.0 -- 1.0 mV Input Impedance 1300 -- 2550 Output Impedance 1400 -- 3000 Response Time (10% to 90%) -- 1.0 -- ms Temperature Error Band 0 -- 85 C Offset Stability -- 0.5 -- %VFSS Sensitivity Linearity Temperature Effect on Full Scale Span 3-338 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... SYSTEM DESIGN As mentioned in the introduction, the lowest pressure devices in the Motorola portfolio are rated at a full-scale pressure of 10 kPa (40 of H2O). The calibrated and temperature compensated, 10 kPa device (MPX2010) is specified to operate at a 10 Vdc supply voltage and produce 25 mV (nominal) at the full-scale pressure of 10 kPa. This translates to a 0.25 mV/(V*kPa) pressure sensitivity. Additionally, the absolute maximum supply voltage specified is 16 Vdc. Thus, the maximum full-scale output signal that can be achieved without exceeding the maximum supply voltage rating is 40 mV, or 60% greater than the output at the 10 Vdc specification. So, a 60% increase can be achieved in the output signal of the sensor for the 0-10 kPa pressure range, or the same signal level of 25 mV can be preserved over a proportionally lower applied pressure range (i.e., 0-6.25 kPa). The point here is that increasing the dc supply excitation only produces limited improvement in the output signal level. Much greater gains in output signal level (sensor span) can be obtained, if it is possible to operate the sensor at significantly higher voltages. Since the thermal/power dissipation limitation imposed by the maximum dc supply AN1551 voltage can be avoided by using a pulsed excitation at a low duty-cycle (on-time) and reasonable period, and second order junction effects do not occur until much higher voltages, the sensor output can be greatly increased by operating at a much higher ac voltage than permitted by the dc counterpart of this same higher voltage. As an example, industrial applications like HVAC have 24 V commonly available, and we want to accurately measure pressures below 10 H2O. To achieve a 1-2% of full-scale accuracy (based on temperature drift errors, system noise, device tolerance, power supply variation/rejection, etc.), 9-12 mV is the typical minimum full-scale span that is the desired target for the pressure range of interest. For the MPX2010 pulsed at 24 V, we obtain 15 mV of output for an applied pressure of 10 H2O (2.5 kPa). This same sensor device will only produce 6.25 mV at its normally specified supply of 10 V and 2.5 kPa, thus not meeting the signal-to-noise ratio criteria for a 1-2% accuracy performance. This smart sensing solution is intended to sense full-scale pressures below 10 H2O with 1% of full-scale pressure resolution and better than 2% of full-scale accuracy. The following subsystems comprise the hardware portion of this solution (see Figure 1): PRESSURE SENSOR SIGNAL CONDITIONING SWITCHING CIRCUITRY LOW VOLTAGE INHIBIT 5 V 5% REGULATOR 8-BIT MICROCONTROLLER VPP Dout Din SCLK CS POWER SUPPLY REJECTION CIRCUITRY VCC Gnd Figure 1. Smart Sensing Block Diagram Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-339 AN1551 Freescale Semiconductor, Inc. * high-side switch pulsing circuitry * signal-conditioning amplifier interface with resistors to adjust the sensor's amplified, full-scale span and zero-pressure offset * on-chip resources of a complete 8-bit microcontroller (MCU) * MCU oscillator circuitry (4 MHz) * 5 V 5% linear voltage regulator * low-voltage inhibit (LVI) supervisory voltage monitoring circuit * resistor divider connected to the sensor's power supply bias Freescale Semiconductor, Inc... to sense the excitation voltage across the sensor These subsystems are explained as follows to provide an understanding of the system design and its intelligent features (refer to Figure 2). Pulsing Circuitry As previously mentioned, the sensor's output is ratiometric to the excitation voltage across the sensing element; the sensor's sensitivity increases with increasing supply voltage. Thus, to detect low pressures and minute changes in pressure, it is desirable to operate the sensor at the highest possible excitation voltage. The maximum supply voltage at which the sensor can reliably operate is determined by one or both of the following two limitations: (1) maximum allowable sensor die temperature, (2) maximum supply voltage available in the sensing application/system. In terms of thermal/power dissipation, the maximum voltage that can be supplied to the sensor on a continuous basis is relatively low compared to that which can be pulsed on the sensor at a low duty-cycle. The average power that is dissipated in the sensor is the square of the average sensor excitation voltage divided by the input resistance of the sensor. When the sensor's supply bias is operated in a pulsed fashion, the average excitation voltage is simply the product of the dc supply voltage used and the percent duty-cycle that the dc voltage is "on." The pulsing circuitry is a high-side switch (two small-signal switching transistors with associated bias resistors) that is controlled via the output compare (TCMP) pin of the MCU. The output compare timer function of the MCU provides a logic-level pulse waveform to the switch that has a 2-ms period and a 200-s on-time (Note: this is user-programmable). Figure 2. System Schematic Signal Conditioning Even with pulsing at a relatively high supply voltage, the pressure sensing element still has a full-scale output that is only on the order of tens of millivolts. To input this signal to the A/D converter of the MCU, the sensing element output must be amplified to allow adequate digital resolution. A basic two-operational amplifier signal-conditioning circuit is used to provide the following desired characteristics of an instrumentation amplifier interface: 3-340 * high input impedance * low output impedance * differential to single-ended conversion of the pressure sensor signal * moderate gain capability Both the nominal gain and offset reference pedestal of this interface circuit can be adjusted to fit a given distribution of sensor devices. Varying the gain and offset reference pedestal www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. is desirable since pressure sensors' full-scale span and zero-pressure offset voltages will vary somewhat from lot to lot and unit to unit. During software calibration, each sensor device's specific offset and full-scale output characteristics will be stored. Nonetheless, a variable gain amplifier circuit is desirable to coarsely tune the sensor's full-scale span, and a positive or negative dc level shift (offset pedestal adjustment) of the pressure sensor signal is needed to translate the pressure sensor's signal-conditioned output span to a specific level (e.g., within the high and low reference voltages of the A/D converter). Freescale Semiconductor, Inc... Microcontroller The microcontroller performs all of the necessary tasks to give the smart sensor system the specified performance and intelligent features. The following describes its responsibilities: * Creates the control signal to pulse the sensor. * Samples the pressure sensor's output. * Signal averages a programmable number of samples for noise reduction. * Samples a scaled-down version of the pressure sensor supply voltage. Monitoring the power supply voltage allows the microcontroller to reject sensor output changes resulting from power supply variations. * Uses serial communications interface (SPI) to receive commands from and to send sensor information to a master MCU. Resistor Divider for Rejection of Supply Voltage Variation Since the pressure sensor's output voltage is ratiometric to its supply voltage, any variation in supply voltage will result in variation of the pressure sensor's output voltage. By attenuating the supply voltage (since the supply voltage may exceed the 5 V range of the A/D) with a resistor divider, this scaled voltage can be sampled by the microcontroller's A/D converter. By sampling the scaled supply voltage, the microcontroller can compensate for any variances in the pressure sensor's output voltage that are due to supply variations. This technique allows correct pressure determination even when the pressure sensor is powered with an unregulated supply. SOFTWARE DESCRIPTION The smart sensor system's EPROM resident code provides the control pulse for the sensor's excitation voltage and performs calibration with respect to a wide range of excitation voltages (20 ~ 28 V typically for HVAC). Pressure measurement averaging is also incorporated to reduce both signal error and noise. In addition, the availability of a serial communications interface allows a variety of software commands to be sent to the smart sensor system. The following brief outline provides a more detailed description about the software features included in the smart sensor system. Software Calibration and Power Supply Rejection Only six 8-bit words of information are stored both to calibrate the smart sensor system for a given sensor device and to store the relationship between sensor output and power supply voltage. This information is used to reduce errors due to device-to-device variations and to reject variations in power supply voltage that can introduce error into the pressure measurement. The sensor's amplified output at the zero-pressure offset and full-scale pressure are stored at each of two different supply voltages. In addition, the scaled and digitized representation of the applied supply voltages is stored. Compensating for power supply variation in software allows higher performance with lower tolerance, or even unregulated, supply voltages. For HVAC applications, where a 24-Vac line voltage will be simply rectified and filtered to provide a crude 24-Vdc supply, this approach has major performance benefits. The impact on applications where a regulated supply is available is that a lower-cost regulator or dc-to-dc converter can be used without compromising system accuracy significantly. A/D Sample Averaging Noise inherent to the 8-bit A/D successive approximation conversion method used by the smart sensor accounts for 1-bit resolution. Signal noise, which exhibits a measured peak-to-peak range larger in magnitude than 1 bit of A/D resolution, can be minimized by a sample averaging technique. The current technique uses 16 A/D converted pressure samples, sums the result, and divides by 16 (the number of samples) to get the average: S n AVG = 1 5 V Regulator A 5 V 5% voltage regulator is required for the following functions: * To provide a stable 5 V for the high voltage reference (VRH) of the microcontroller's A/D converter. A stable voltage reference is crucial for sampling any analog voltage signals. * To provide a stable 5 V for the resistor divider that is used to level shift the amplified zero-pressure offset voltage. Low Voltage Inhibit (LVI) Circuitry Low voltage inhibit circuitry is required to ensure proper power-on-reset (POR) of the microcontroller and to put the MCU in a known state when the supply voltage is decreased below the MCU supply voltage threshold. Motorola Sensor Device Data AN1551 (an) ; where n = 16 n (1) Assuming a gaussian distribution of noise, this averaging technique improves the signal-to-noise ratio (SNR). Smart Sensor Unit ID and Software Revision Level This solution may be implemented as a single sensing system using a nondedicated MCU to provide the sensing function and smart features or as a slaved smart sensor (with dedicated sensing MCU) that communicates over a serial bus to a master controller or microprocessor (Host). Part identification and software revision level can also be read on request from the master MCU. This information is utilized by the master MCU to determine what the full-scale pressure range of a given smart sensor unit is. This allows for multiple sensor units with different pressure ranges to be controlled and sensed from a single master MCU. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-341 Freescale Semiconductor, Inc. AN1551 Table 2. Software Command Codes Function (Command Codes) Command from Host Data from Smart Sensor Request Pressure $01 $00-$FF Dynamic Zero $02 -- Undo Dynamic Zero $03 -- Pressure Range $04 TBD Pressure Range (from 0 to 255), Freescale Semiconductor, Inc... Communication The serial peripheral interface (SPI) is used to communicate to a master/host MCU. The master MCU initiates all I/O control and sends commands to the slave regarding data requests, calibration, etc. The command codes are parsed at the slave in a look-up table, at which time the corresponding request is serviced via subroutine. Table 2 lists the Master/Slave commands. Request Pressure Returns the percent of full-scale pressure applied to the sensor in the form of $00 (0) through $FF (255) and is equivalent to: (0 where Y 255) 255 x FS = Measured Pressure (2) (This calculation is performed by the master MCU.) Dynamic Zero Assigns current input pressure as the offset value, in order to use a nonzero pressure as the offset reference. Undo Dynamic Zero Resets offset to the original stored offset (see Dynamic Zero). Pressure Range Returns a value representing the sensor's full-scale pressure range. Figure 3. SPI Timing Diagram 3-342 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. SOFTWARE EXAMPLES The following example listings show how a user may communicate with the smart sensor via a master MCU. The software example shown assumes that the master MCU is an MC68HC11. Any MCU with the proper I/O functionality will operate similarly with the smart sensor system. When using parallel I/O instead of an SPI port to interface the smart sensor, the user must "bit bang" the clock and data AN1551 out of the parallel I/O, so as to simulate the SPI port. As long as the timing relationships of data and clock follow those of Figure 3 (see also Table 3), the smart sensor will function properly when interfaced to a processor with a parallel type interface. In the following two code examples, the sensor unit is interfaced to the master MCU via the SPI port, and the sensor's CS input is connected to the HC11's Port D pin 5. This example is coded in `C' for the MC68HC11: Freescale Semiconductor, Inc... /* FIRST INITIALIZE THE I/O (INCLUDE A HEADER FILE TO INCLUDE I/O DEFINITIONS) */ void init_io(void) { PORTD = 0X29; /* SS* PD5 = 1, PD3 = 1, PD0 = 1 */ DDRD = 0X3B; /* SS* PD5 = 1, PD3 = 1, PD1 = 1, PD0 = 1 */ SPCR = 0X5E; /* ENABLE THE SPI, MAKE MCU THE MASTR, SCK = E CLK /4 */ /* I/O INITIALIZATION IS COMPLETE */ } /* WE NEED A FUNCTION TO WRITE TO AND READ FROM THE SPI */ write_spi(char data) { SPDR = data; /* WRITE THE DATA TO THE SPI DATA PORT */ while( ! (SPSR & 0x80 )); /* WAIT UNTIL DATA HAS SHIFTED OUT OF AND BACK INTO THE SPI */ return(SPDR): /* RETRIEVE THE RESULTS OF THE LAST COMMAND TO THE SENSOR AND RETURN */ } /* NOW WE NEED TO CALL THE ABOVE */ void main(void) { char rtn_data; /* rtn_data IS THE RETURNED DATA FROM THE SENSOR */ init_io(); while(1) /* JUST LOOP FOREVER */ rtn_data = write_spi(0x01); /* 0x01 IS THE COMMAND TO THE SENSOR THAT REQUESTS PRESSURE. THE VALUE IN rtn_data WILL BE IN THE RANGE OF 0..0XFF = 0..100% FULL SCALE PRESSURE THE SECOND TIME THROUGH THE LOOP. THE INITIAL TIME THROUGH THE LOOP, THE DATA RETURNED IS INDETERMINATE */ } The next example is coded in assembly for the MC68HC11: * PORT OFFSETS INTO THE I/O MAP PORTS EQU $1000 PORTD EQU $8 DDRD EQU $9 SPCR EQU $8 SPSR EQU $29 SPDR EQU $2A ORG $E000 * FIRST INITIALIZE THE I/O INITIO LDX #PORTS LDAA #$29 STAA PORTD,X LDAA #$3B STAA DDRD,X LDAA #$5E STAA SPCR,X * RTS Motorola Sensor Device Data ASSUME THE I/O STARTS AT $1000 BASE ADDRESS OF THE I/O SS* PD5 = 1, PD3 = 1, PD0 = 1 SS* PD5 = 1, PD3 = 1, PD1 = 1, PD0 = 1 ENABLE THE SPI, MAKE MCU THE MASTR, SCK = E CLK /4 I/O INITIALIZATION IS COMPLETE www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-343 Freescale Semiconductor, Inc. AN1551 *WE NEED A SUBROUTINE TO WRITE TO AND READ FROM THE SPI *TO CALL THIS ROUTINE LOAD ACCUMULATOR A WITH THE COMMAND DATA *AND JSR WRITSPI. WHEN THE ROUTINE RETURNS, ACCUMULATOR A *CONTAINS THE DATA RETURNED FROM THE SENSOR WRITSPI WRLOOP LDX STAA BRCLR LDAA * #PORTS BASE ADDRESS OF THE I/O SPDR,X SEND THE COMMAND TO THE SENSOR 7,SPSR,WRLOOP LOOP UNTIL THE DATA HAS SHIFTED OUT OF AND BACK INTO THE SPI SPDR,X RETRIEVE THE RESULTS OF THE LAST COMMAND TO THE SENSOR RTS * NOW WE NEED TO CALL THE ABOVE */ START JSR INITIO SET-UP THE I/O LOOP LDAA #$1 1 IS THE COMMAND TO THE SENSOR THAT Freescale Semiconductor, Inc... * * * * * * JSR ... WRITSPI BRA LOOP REQUESTS PRESSURE SEND THE COMMAND TO THE SENSOR. THE VALUE RETURNED IN ACCUMULATOR A WILL BE IN THE RANGE 0..0XFF = 0..100% FULL SCALE PRESSURE THE SECOND TIME THROUGH THE LOOP. THE INITIAL TIME THROUGH THE LOOP, THE DATA RETURNED IS INDETERMINATE DATA FROM THE SENSOR Table 3. SPI Timing Characteristics Characteristic Frequency of Operation Symbol Min Max Unit fOP dc 525 kHz Cycle Time tSCLK -- 1920 ns Clock (SCLK) Low Time tSCLKL 932 -- ns Dout Data Valid Time tV -- 200 ns Din Setup Time tS 100 -- ns Din Hold Time tH 100 -- ns On-Bus Delay Time tD1 1 -- ms Off-Bus Delay Time tD2 -- 50 s Chip Select Period tD3 TBD -- ms SERIAL DATA OUTPUT FORMAT CONCLUSION The serial data output is an 8-bit number of value 0-255. This number represents the current applied pressure as a percentage of the full-scale pressure rating of the smart sensor. The master MCU can simply consider an output of "0" to be zero pressure and "255" to be full-scale pressure. To convert this number to engineering units, such as inches of water ( H2O), the master MCU must multiply the smart sensor output (0-255) by the full-scale pressure of the smart sensor in H2O and then divide (normalize) by 255. See equation 2. The master MCU can either use an absolute number for the full-scale pressure of the smart sensor (as indicated previously) or can query each smart sensor that is connected to the serial bus for its rated pressure range. The latter technique allows multiple smart sensors of various full-scale pressure ranges to be communicating with a single master MCU, without the need for an absolute addressing scheme that contains full-scale pressure information for each sensor. A smart sensing system that achieves high performance for low-pressure applications has been presented here. The key performance advantage of the smart sensor system is that it takes advantage of the fact that the output of the actual sensing element is ratiometric (linearly proportional) to the excitation voltage applied to the sensing element. A sensor device is pulsed at a much higher than normally specified voltage and a low duty-cycle for the purpose of increased sensitivity. Although some of the sensor's parasitic drawbacks are increased in magnitude, some of the sensor's negative characteristics are lessened, and other sources of error and noise in the system are reduced. The net effect is that a better signal-to-noise ratio is obtained. This, combined with several other performance-enhancing smart features, provides better pressure resolution and accuracy than inherent in the sensor device alone. 3-344 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. provide the reader with an understanding of how low-pressure capability can be greatly enhanced via a smart sensor system approach. ACKNOWLEDGMENTS I wish to acknowledge my colleagues Bill Lucas and Warren Schultz for their outstanding efforts and major contributions to the pursuit of low-pressure sensing technology. Freescale Semiconductor, Inc... Besides the sensor excitation pulsing and output sampling functions, a low-cost MCU provides the performance- enhancing features of signal averaging, software calibration, and software power supply rejection. The added-functionality of intelligent communications capability, serial digital output flexibility, and local control and decision-making capability are also at the user's disposal. The development history, system design, software functions, example communications routines, and serial output format have been detailed to AN1551 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-345 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Designing Sensor Performance Specifications for MCU-based Systems AN1556 Prepared by: Eric Jacobsen and Jeff Baum Sensor Systems Engineering Group Motorola Sensor Products Division Phoenix, AZ Freescale Semiconductor, Inc... INTRODUCTION When designing a circuit for a sensor system, it is desirable to use fixed-value components in the design. This makes the system easier and cheaper to produce in high volume. The alternatives to using fixed-value circuitry are very expensive and usually impractical: laser-trimming resistances, manually calibrating potentiometers, or measuring and selecting specific component values are all very labor-intensive processes. However, every sensor has device-to-device variations in offset output voltage, full-scale output voltage, dynamic output voltage range (difference between the full-scale output voltage and zero-scale output voltage which is commonly referred to as the span), etc. Moreover, these same parameters also vary with temperature -- e.g., temperature coefficient of offset (TCVoff) and temperature coefficient of full-scale span (TCVFSS). To further complicate this situation, the fixed-value circuit in which a sensor is applied also has variation -- e.g., the voltage or current regulator and resistors all have a specified tolerance. Since today's unamplified solid-state sensors typically have an output voltage on the order of tens of millivolts (Motorola's basic 10 kPa pressure sensor, MPX10, has a typical full-scale span of 58 mV, when powered with a 5 V supply), a major part of the fixed-value circuitry is a gain stage that amplifies the signal to a level that is large enough for additional processing. Typically, this additional processing is digitization of the amplified analog sensor signal by a microcontroller's A/D converter. To obtain the best signal resolution with an A/D, the sensor's amplified dynamic output voltage range should fill as much of the A/D window (difference between the A/D's high and low reference voltages) as possible without extending beyond the high and low reference voltages (i.e., the zero-pressure offset voltage must be greater than or equal to the low reference voltage, and the full-scale output voltage must be less than or equal to the high reference voltage). In any case, the device-to-device, temperature, and circuit variations create a design dilemma: with a fixed-value amplifier circuit, the gain as well as any dc level shift incorporated in the amplifier design are fixed. If the variation of any of the aforementioned sensor parameters is too large, the amplified sensor output may saturate the amplifier near either its high or low supply rail or may extend beyond either the high or low reference voltages of the A/D converter. In either case, error (non-linearity) results in the 3-346 system. To avoid this scenario, the solution is to design a fixed-value circuit that optimizes performance (signal resolution) while taking into account all possible types of variation that may cause the sensor output to vary. In other words, the goal of this fixed-value sensor system is to attain the best performance possible while ensuring through design, regardless of any system variation, that the sensor's amplified output will ALWAYS be within the saturation levels of the amplifier and the high and low reference voltages of an A/D converter. The implication of ensuring that the sensor's amplified output is always unsaturated and within the high and low reference voltages of the A/D is that an accurate software calibration of the sensor's output is possible. By sampling the sensor's output voltage at a couple of points at room temperature (zero and full-scale output, for example), all the room temperature device-to-device and circuit variations are nullified. Obviously, temperature variations will create error in the system (sensor's output voltage will drift with changing temperature), but, by design, the sensor's output voltage will remain within the A/D's valid range. This paper discusses a methodology that optimizes a sensor system's performance while considering device-to-device, temperature, and circuit variations that can create variation in the amplified sensor output. The methodology starts with a desired performance and some established parameters and then considers each type of variation in a worst case analysis to determine if the desired performance is attainable. While this paper discusses this methodology for pressure sensors and a specific amplifier topology, the methodology is applicable to low-level, differential-voltage output sensors and amplifier circuits in general. Two specific examples are presented that apply this methodology. The first example uses Motorola's MPX10 pressure sensor, and the second example uses Motorola's MPX2010 pressure sensor. Both sensors have a full-scale rated pressure of 10 kPa; the difference between the devices is the MPX2010 has on-chip calibration and temperature compensation circuitry to calibrate and temperature compensate the zero-pressure offset voltage and span. The comparison of these two devices will emphasize how dramatically device-to-device and temperature variations, if not compensated, can affect a system's overall performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1556 THE EXAMPLE CIRCUIT resistors that establish the gain and dc voltage level shift (VREF) are considered in the methodology. The voltage regulator's device-to-device tolerance is 5%, and each resistor's tolerance is 1%. Referring to Figure 1, both pressure sensors are interfaced to the same amplifier circuit topology. In Tables 1 and 2, the relevant characteristics for the MPX10 and MPX2010 show the device-to-device and temperature variations. Additionally, the tolerances on the voltage regulator and the Vin 5 V REG. ( 5%) IN OUT VS GND R2 RREF1 VREF R4 U1 R1 - + R3 VO TO A/D - + U1 LM33272 Freescale Semiconductor, Inc... RREF2 X1 MPX10 OR MPX2010 S- S+ Figure 1. MPX10/MPX2010 Circuit Schematic Table 1. MPX10 Variation Characteristics Characteristic (VS = 5.0 V) Symbol Min Typ Max Unit Pressure Range POP 0 -- 10 kPa Full-Scale Span VFSS 33 58 83 mV Voff 0 33 58 mV TCVFSS - 0.22 - 0.19 - 0.16 %/C TCVoff -- 15 -- V/C Zero Pressure Offset Temperature Coefficient of Full-Scale Span (see Note 1) Temperature Coefficient of Offset (see Note 2) Note 1: Slope of end-point straight line fit to full-scale span at - 40C and +125C relative to 25C Note 2: Slope of end-point straight line fit to zero pressure offset at - 40C and +125C relative to 25C Table 2. MPX2010 Variation Characteristics Characteristic (VS = 5.0 V) Symbol Min Typ Max Unit Pressure Range POP 0 -- 10 kPa Full-Scale Span VFSS 12 12.5 13 mV Voff - 0.5 -- 0.5 mV TCVFSS - 1.0 -- 1.0 %FSS TCVoff - 0.5 -- 0.5 mV Zero Pressure Offset Temperature Effect on Full-Scale Span (see Note 1) Temperature Effect on Offset (see Note 2) Note 1: Maximum change in full-scale span at 0C and 85C relative to 25C Note 2: Maximum change in offset at 0C and 85C relative to 25C The amplifier topology used is a two-operational amplifier gain stage that has all the desirable characteristics of a differential-signal instrumentation amplifier: * high input impedance * low output impedance * differential to single-ended conversion of the input signal * high gain capability * dc level shifting capability Motorola Sensor Device Data For good common mode rejection, the following resistor ratios are used: R4 R1 R3 R2 With this simplification, the transfer function of the amplifier is R4 VO 1 (S - S-) VREF R3 + +( ) ) ) www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com ) 3-347 Freescale Semiconductor, Inc. AN1556 Where the gain is ( RR43 ) 1), the pressure sensor's differential output voltage is the quantity (S+ - S-), and the positive dc voltage level shift, created by the voltage divider comprised of RREF1 and RREF2, is VREF. In addition to using the above resistor ratios to preserve the common mode rejection, the effective resistance of the parallel combination of RREF1 and RREF2 should be a low impedance to ground relative to the resistance of R1. Freescale Semiconductor, Inc... RESOLUTION AND FACTORS THAT AFFECT IT Performance of a pressure sensor system is directly related to its resolution. Resolution is the smallest increment of pressure that the system can resolve -- e.g., a system that measures pressure up to 10 kPa (full-scale) with a resolution of 1% of full-scale can resolve pressure increments of 0.1 kPa. Similarly, the resolution (smallest increment of voltage) of an 8-bit A/D converter with a 5 V window (a high reference voltage of 5 V and a low reference voltage of 0 V) is 5 V 255 (8 bits) + 19.6 mV Many pressure sensor systems interface an A/D converter. If the above system example requires 1% resolution when interfaced to an A/D, the pressure sensor signal's span must be at least + 19.6 mV 1.96 V 1% If the system resolution required is 0.5%, the pressure sensor signal's span must be at least + 19.6 mV 3.92 V 0.5% From these examples, the greater the resolution required, the greater the sensor's amplified span must be to meet the resolution requirement. Since a pressure sensor's span before amplification is only on the order of tens of millivolts, the amplifier must be designed to provide the minimum span that gives the desired resolution. If the amplifier has a fixed gain, any device-to-device variation in the sensor's unamplified span will result in variation of the amplified span. If, for example, the sensor's span variation results in an amplified span that is smaller than required, the resolution of the system will not be as high as desired. Alternately, if the sensor's span variation results in an amplified span that is larger than required, the resolution will be better than desired, BUT the amplified span may also either saturate the amplifier near its supply rails or extend outside the high and low reference voltages of the A/D. Voltages above the high reference will be digitally converted as 255 decimal (for 8-bit A/D), and voltages below the low reference will be converted as 0. This creates a non-linearity in the analog-to-digital conversion and in the overall system transfer function. As presented above, the variation of the sensor's span creates a dilemma: how does one design a fixed-gain amplifier that gives the desired resolution, does not violate the 3-348 limits of the linear output ranges of the op-amps and A/D converter, and also accommodates the complete distribution of possible sensor spans? The same question is presented to the additional sources of variation: device-to-device variation in the zero-pressure offset voltage and temperature effects on both the sensor's span and zero-pressure offset voltage. Also any component tolerances for the voltage regulator and resistors must be considered. Designing the system when only one source of variation is involved is not difficult; however, when all of these variations are interacting, the solution becomes complicated. The rest of this paper describes a design methodology that considers all of the above variations and their interactions. Worst case limits will be used in designing the fixed-value system. RESOLUTION vs. HEADROOM As stated previously, the amplified span of the sensor must "fit" within the high and low references of an A/D to avoid any nonlinearity errors. And the span must also be large enough to provide the resolution required for the application. Any part of the A/D's "window" that is not used for the sensor's dynamic signal range is called headroom. Headroom may be thought of as a cushion between the high and low reference voltages and the sensor's dynamic output range. This "cushion" is used to allow the sensor's dynamic range to move and/or vary within the A/D's window. A general description is shown in Figure 2. The total amount of sensor output signal variation (due to temperature effects, device-to-device variation, and interface circuit component tolerances) cannot exceed the headroom that is available for the requisite amount of system resolution. A larger sensor span (more bits used for signal resolution) means a smaller amount of headroom available to accommodate sensor parameter and interface circuit variations. This makes the tradeoff between resolution and variation obvious. The more variation in the system, the more headroom that is required to allow for the variation and, consequently, less of the A/D window is available for the sensor's "true-signal" span. Less span results in poorer resolution (less bits used for resolving sensor output signal). A/D HIGH REFERENCE OR HIGH SAT. LEVEL OF AMPLIFIER FULL-SCALE OUTPUT VOLTAGE HEADROOM SENSOR'S FULL-SCALE VOLTAGE SPAN A/D'S OR AMPLIFIER'S DYNAMIC RANGE ZERO PRESSURE OFFSET VOLTAGE A/D LOW REFERENCE OR LOW SAT. LEVEL OF AMPLIFIER HEADROOM Figure 2. Sensor's Full-Scale Span vs. Headroom www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. THE METHODOLOGY TO OPTIMIZE PERFORMANCE AN1556 A/D'S DYNAMIC RANGE The methodology starts with defining all the known parameters. The parameters with an asterisk (*) are specified at 25C. * Resolution * MaxFSS (*) * * * Freescale Semiconductor, Inc... * * * * * * * * = Desired system resolution = Maximum full-scale voltage span of = the pressure sensor MinFSS (*) = Minimum full-scale voltage span of = the pressure sensor TCVFSS (*) = The maximum temperature coefficient = of the sensor's full-scale voltage span MaxSensOff (*) = The maximum zero pressure offset = voltage of the pressure sensor MinSensOff (*) = The minimum zero pressure offset = voltage of the pressure sensor TCVoff = The sensor's maximum temperature = coefficient of offset voltage Vlo = The low saturation level of the amplifier = or low reference voltage of an A/D = (whichever is most limiting case) Vhi = The high saturation level of the = amplifier or the high reference voltage = of an A/D (whichever is most limiting = case) = The reference voltage for positive dc VREF = voltage level shifting = The voltage regulator tolerance Vtol = The application's minimum operating MinTemp = temperature = The application's maximum operating Maxtemp = temperature These parameters are either chosen for the application (e.g., system resolution) or can be determined from the sensor's data sheet. Tables 1 and 2 provide the necessary information for the design examples presented here. Note: The data in Tables 1 and 2 are scaled for a 5 V supply voltage, whereas the MPX10 and MPX2010 data sheets are specified at a 3 V and 10 V supply voltage, respectively. The following steps outline the methodology that will be applied to the MPX10 in the first design example and then applied to the MPX2010 in the second design example. 1. Determine/choose the required Resolution for the system. 2. Calculate the number of steps required for the chosen resolution. The resolution determines the number of steps into which the pressure signal needs to be broken [see Figure 3 where an 8-bit A/D (255 steps of resolution) is assumed]. A conservative approach to determining this number of steps is to assume that with an A/D, the digital quantization of the pressure signal can be plus or minus one step. Therefore, assume that it takes twice the number of steps previously determined to resolve a given minimum incremental pressure. The number of steps for the chosen resolution is Number of Steps 2 * 100 + Resolution The scaling factor of 100 in the numerator converts the resolution from a percentage to a decimal fraction. Motorola Sensor Device Data STEP 255 A/D HIGH REFERENCE A/D LOW REFERENCE STEP 127 STEP 0 Figure 3. The 255 Digital Steps of an 8-Bit A/D 3. Calculate the minimum amplified sensor span (defined as the Minimum Required Span -- see Figure 4) required for this resolution requirement. Using an 8-bit A/D with a 5 V window where one step equals 19.6 mV (for the nominal regulator voltage), the minimum amplified sensor span is Minimum Required Span + (Number of Steps)*(19.6 mV) A/D HIGH REFERENCE FULL-SCALE OUTPUT VOLTAGE MAXIMUM SPAN A/D'S MINIMUM DYNAMIC REQUIRED RANGE SPAN ZERO PRESSURE OFFSET VOLTAGE A/D LOW REFERENCE Figure 4. The Minimum Required Span for the Required Resolution and the Maximum Span Due to Sensor Span Variations 4. Calculate the amplifier's gain. The gain must be large enough to achieve, over the entire distribution of sensor spans, the Minimum Required Span. Therefore, this gain is calculated using the smallest pressure sensor voltage span, MinFSS. By using the worst case smallest pressure sensor voltage span to calculate the gain, the Minimum Required Span (the minimum span that will achieve the resolution requirement) is guaranteed for the entire distribution of sensor spans. The worst case minimum full-scale sensor span will occur at the hottest temperature, Maxtemp, in the application (not exceeding the operating temperature of the sensor), since the span decreases with increasing temperature (TCV FSS is negative). Gain Required Span + [MinFSS] Minimum [1 ) TCV (Maxtemp-25)] * FSS * The term [1 + TCVFSS * (Maxtemp - 25)] is the temperature effect on the span. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-349 Freescale Semiconductor, Inc. AN1556 Freescale Semiconductor, Inc... Summarizing (through Step 4), the calculations are based on a minimum desired resolution. The resolution requirement determines the number of steps or "pieces" into which the signal must be broken. This number of steps or "pieces" multiplied by the number of millivolts per step equals a minimum voltage range which is defined as the Minimum Required Span. Finally to ensure that this Minimum Required Span is achieved over the entire distribution of sensor spans, the gain is calculated using the worst case smallest sensor span. Note: The gain also will have variation due to resistor tolerances in the amplifier circuit. To ensure that the system variation due to resistor tolerances is negligible when compared to other sources of variation, the system should be designed using resistors with tolerances of 1% or better. 5. Calculate the worst case Maximum Span. The Maximum Span is the largest possible span and is calculated using the maximum full-scale sensor voltage span, MaxFSS, and the Gain. The worst case maximum full-scale sensor span occurs at the coldest temperature, MinTemp. After calculating the Maximum Span, the remaining dynamic range within the A/D's window or saturation levels of the amplifier is the smallest number of "bits" (most limiting case) available for headroom. Maximum Span = [Gain] * [MaxFSS] * [1 + TCVFSS * (MinTemp - 25)] The term [1 + TCVFSS * (MinTemp - 25)] is the temperature effect on the span. The Maximum Span calculated from the above equation is depicted in Figure 4. 6. Calculate the Calculated Headroom. The Calculated Headroom is a subset of the general term "headroom" because it reserves "bits" in the A/D's dynamic range only for the sources of variation from the sensor's zero-pressure offset voltage. Headroom, in general, is reserved for all sources of variation: system components, resistor tolerances (if significant), and the sensor. However, the largest part of the "headroom" must be reserved for the device-to-device variations and temperature effects on the sensor's zero-pressure offset voltage. Therefore, the sources of variation from the other system components are subtracted immediately from the headroom so that the focus can be on the sensor-related variations (refer to Figure 5 and the following equation for the Calculated Headroom). For these design examples, the supply is a single, regulated 5 V 5% supply (the regulator 's tolerance is referred to as Vtol). An assumption for a typical rail-to-rail op-amp's saturation levels (referred to as Vlo and Vhi) is 0.2 V above the low supply rail (ground) and 0.2 V below the high supply rail (5 V). Additionally, the worst case (smallest) supply voltage is 5 V - 5% or 4.75 V. Calculated Headroom tol ) - 2 + 5 * (1- V100 * Vlo - Maximum Span The preceding equation assumes that the difference between Vhi and the high supply rail (or high reference of an A/D) is equal to the difference between Vlo and the low supply rail (or low reference of an A/D); thus the term (2 * Vlo). 3-350 VS's NOMINAL VALUE (NOT INCLUDING Vtol) VS (INCLUDING Vtol) AND A/D HIGH REFERENCE HIGH SAT. LEVEL OF AMPLIFIER FULL-SCALE OUTPUT VOLTAGE MAXIMUM SPAN AMPLIFIER'S DYNAMIC RANGE ZERO PRESSURE OFFSET VOLTAGE LOW SAT. LEVEL OF AMPLIFIER CALCULATED HEADROOM GROUND AND A/D LOW REFERENCE Figure 5. From Ground to VS, a Section of Voltage Is Reserved for Each Source of Variation Step 6 is considered a pivotal step because it transitions the methodology's calculations from the performance requirements to the headroom requirements. Up to Step 6, the methodology considered only the span of the sensor to guarantee a minimum resolution despite device-to-device variation, component tolerances, and temperature effects. Upon calculating the Calculated Headroom, the remaining steps of the methodology that are detailed below consider the offset variations (due to device-to-device and temperature). These offset variations are added together to comprise what is defined as the Required Headroom which is the required number of "bits" in the A/D's dynamic range needed to accommodate the offset variations. This Required Headroom is then compared to the Calculated Headroom (from the preceding calculation) to determine if the Calculated Headroom is sufficient to allow for the offset variations (i.e., the Calculated Headroom must be greater than or equal to the Required Headroom). In the case that the Calculated Headroom is not sufficiently large, relaxing the resolution requirement or reducing, if possible, the variation of either offset, span, component tolerances, or a combination of all three is required. 7. Calculate the maximum offset drift due to temperature fluctuations (defined as the Maximum Temperature Effect on Offset). A conservative approach to this calculation is to determine the maximum total voltage change of offset over the application's entire operating temperature range. This maximum change of offset is the product of the Gain, TCVoff, and the application's entire operating temperature range (from Maxtemp to MinTemp). Since the temperature coefficient of offset can be positive or negative, the offset may increase or decrease with increasing temperature and, likewise, for decreasing temperature. Though this step only considers the maximum magnitude of the change in offset due to temperature, a segment in the Required Headroom is reserved for both possibilities of a positive or negative temperature coefficient of offset (see Figure 6). The sign (positive or negative) of the total offset change due to temperature is also considered in upcoming steps. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Maximum Temperature Effect on Offset = (Gain) * (TCVoff) * (Maxtemp - MinTemp) AN1556 Maximum Offset = [Gain] * [MaxSensOff] + Maximum Temperature Effect on Offset MAXIMUM OFFSET MAX. TEMPERATURE EFFECT ON OFFSET (POSITIVE TEMP. COEFF.) MAX. TEMPERATURE EFFECT ON OFFSET (POSITIVE TEMP. COEFF.) MAX. OFFSET VARIATION REQUIRED (BEFORE ADDING HEADROOM TEMP. EFFECTS) Freescale Semiconductor, Inc... REQUIRED HEADROOM MAX. TEMPERATURE EFFECT ON OFFSET (NEGATIVE TEMP. COEFF.) MAX. TEMPERATURE EFFECT ON OFFSET (NEGATIVE TEMP. COEFF.) MINIMUM OFFSET Figure 6. The Maximum Temperature Effect on Offset 8. Calculate the Maximum Offset Variation. The Maximum Offset Variation is the total amount of the Required Headroom that must be reserved to account for the entire distribution of sensor offsets (at room temperature -- refer to Figure 7). Maximum Offset Variation = [Gain] * [MaxSensOff - MinSensOff] where largest offset is [Gain] * [MaxSensOff] and the smallest offset is [Gain] * [MinSensOff] 9. Calculate the worst case Minimum Offset. The worst case Minimum Offset includes both temperature effects (from Step 7) and device-to-device variations (from Step 8) to determine the smallest possible offset over the entire distribution of sensor offsets and over the operating temperature range. This worst case Minimum Offset occurs when a sensor has a nominal room temperature offset of MinSensOff (smallest offset in the sensor offset distribution) and a negative temperature coefficient so that the offset decreases with increasing temperature. Refer to Figure 7. Minimum Offset = [Gain] * [MinSensOff] - Maximum Temperature Effect on Offset 10. Similar to Step 9, calculate the worst case Maximum Offset. The worst case Maximum Offset includes both temperature effects (from Step 7) and device-to-device variations (from Step 8) to determine the largest possible offset over the entire distribution of sensor offsets and over the operating temperature range. This worst case Maximum Offset occurs when a sensor has a nominal room temperature offset of MaxSensOff (largest offset in the sensor offset distribution) and a positive temperature coefficient so that the offset increases with increasing temperature. Refer to Figure 7. Motorola Sensor Device Data Figure 7. Calculating the Maximum and Minimum Offsets 11. Calculate the Required Headroom. Referring to Figure 7, the Required Headroom is the difference between the Maximum Offset and Minimum Offset and is the amount of voltage range (bits of the A/D) required to allow for device-to-device and temperature variations of the sensor's offset. Required Headroom = Maximum Offset - Minimum Offset 12. Compare the Required Headroom of Step 11 to the Calculated Headroom of Step 6. The Calculated Headroom is the absolute maximum amount of offset variation (due to device-to-device variations and temperature effects) that the system can allow for the desired resolution. If the Required Headroom is greater than the Calculated Headroom, the desired resolution is not attainable for all worst case variations due to temperature effects, component tolerances, and device-to-device variations. Therefore, the requirement to attain the desired system resolution is: Calculated Headroom Required Headroom If this requirement is not met, as stated previously, the alternatives to meeting this requirement are the following: * Relax the Resolution requirement and repeat the methodology. * Reduce (tighten) the span or offset (or both) variation and repeat the methodology. * Reduce temperature coefficients. * Reduce the component tolerances and repeat the methodology. * Repeat the methodology by performing a combination of the above suggestions. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-351 Freescale Semiconductor, Inc. AN1556 Once the above headroom requirement is met, the final step is to determine the proper value of VREF: 13. A dc offset, VREF, is required to position the sensor's span within the A/D window so that no device-to-device or temperature variation nor component tolerances cause the sensor's output to be outside the A/D window. Therefore, calculate the VREF required to ensure that the sensor's smallest zero-pressure offset voltage (Minimum Offset) is greater than or equal to Vlo (refer to Figures 5 and 7). In other words, the sum of the reference voltage and Minimum Offset must be greater than or equal to the amplifier's low saturation voltage: VREF + Minimum Offset Vlo Solving for VREF: Freescale Semiconductor, Inc... VREF Vlo - Minimum Offset Note: The reference voltage, VREF, also will have variation due to resistor tolerances in the resistor divider used to create VREF. To ensure that the system variation due to resistor tolerances is negligible when compared to other sources of variation, the system should be designed using resistors with tolerances of 1% or better. The following design examples use the methodology. DESIGN EXAMPLES WITH THE MPX10 AND MPX2010 The following table lists the methodology's steps. The table entries (names) will correspond to the names used in the methodology outlined above; additionally, the step number (Step 1, etc.) is bracketed ( [ ] ) and superscripted next to the entry to which the step refers. The first column lists the given parameters that should be available in or derived from the appropriate component's (sensor, amplifier, voltage regulator, resistors) data sheet. The second column lists the performance requirements of the sensor system (i.e., this column lists all the calculations that relate to ensuring a minimum sensor span to achieve the desired resolution despite device-to-device variations, temperature effects and component tolerances). The third column lists the calculations that determine the headroom for the system given component tolerances and the device-to-device variations and temperature effects on the sensor's offset. The table and associated system design equations may easily be implemented in a spreadsheet to efficiently perform the required calculations. Table 3. Design Example Using the MPX10 Given Parameters MaxFSS (mV @ 25C) 83 Performance Parameters [1]Resolution (% FSS) 4.5 [5]Maximum Span (V) 2.57 Headroom Parameters [7]Maximum Temperature Effect on Offset (V) 0.03 [8]Maximum Offset Variation (V) 1.76 [9]Minimum Offset (V) - 0.03 [10]Maximum Offset (V) 1.73 [13]VREF (V) 0.23 [6]Calculated Headroom (V) 1.78 [11]Required Headroom (V) 1.75 MinFSS (mV @ 25C) 33 [2]Number of Steps 44 TCVFSS (% FSS/C) - 0.22 [3]Minimum Required Span (V) 0.87 [4]Gain 29 MaxSensOff (mV @ 25C) 58 MinSensOff (mV @ 25C) 0 TCVoff (V/C) 15 VS (V) 5 Vhi (V) 4.8 Vlo (V) 0.2 [12]IS Calculated Headroom Required Headroom ? Vtol (%) 5 Maxtemp (C) 70 MinTemp (C) 0 3-352 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1556 Freescale Semiconductor, Inc... Table 4. Design Example Using the MPX2010 Given Parameters Performance Parameters Headroom Parameters MaxFSS (mV @ 25C) 13 [1]Resolution (% FSS) 1.2 [7]Maximum Temperature Effect on Offset (V) 0.14 MinFSS (mV @ 25C) 12 [2]Number of Steps 167 [8]Maximum Offset Variation (V) 0.55 TCVFSS (% FSS) 1 [3]Minimum Required Span (V) 3.27 [9]Minimum Offset (V) - 0.27 MaxSensOff (mV @ 25C) 0.5 [4]Gain 275 [10]Maximum Offset (V) 0.27 MinSensOff (mV @ 25C) - 0.5 [5]Maximum Span (V) 3.61 [13]VREF (V) 0.47 [6]Calculated Headroom (V) 0.74 [11]Required Headroom (V) 0.55 TCVoff (mV, 0C to 85C) 0.5 VS (V) 5 Vhi (V) 4.8 [12]IS Calculated Headroom Required Headroom ? Vlo (V) 0.2 Vtol (%) 5 Maxtemp (C) 85 MinTemp (C) 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-353 Freescale Semiconductor, Inc... AN1556 Freescale Semiconductor, Inc. DESIGN EXAMPLE COMPARISON SUMMARY CONCLUSION The preceding examples show how sources of variation can affect the overall system resolution. The MPX2010 has on-chip temperature compensation and calibration circuitry to reduce device-to-device variations and temperature effects. Consequently, when designing the fixed-value amplifier circuitry, the resolution possible with the MPX2010 is almost four times greater than the same amplifier circuit using an MPX10. In both examples, both systems' performance (Resolution) are optimized to be the best possible, given the distribution of the sensor device parameters and the other component variations. As stated previously if the methodology's calculations show that the sensor's signal will always be within the dynamic range of the amplifier (and high and low reference voltages of the A/D), a software calibration may then be implemented to nullify any room temperature device-to-device and component variations. It should be noted, however, that this methodology does not consider how to obtain the best performance from a single sensor system. Rather, the focus of the methodology is to obtain the best possible system performance while considering the distribution of device parameters that result from manufacturing and other sources of variation. By considering the sources of variation, the system may then be mass-produced without individually calibrating the sensor system hardware. Obviously, if each sensor system is hand-calibrated, the performance will be better. However, the hand-calibration also requires additional cost and time when producing the sensor system. To guarantee a specified performance when designing a fixed-value circuit for sensor systems, all significant sources of variation must be considered. By considering the sources of variation (device-to-device variations, temperature effects, and component tolerances), the system may be designed so that the specified performance (resolution) is achieved while still keeping the sensor's amplified dynamic range within the A/D window (or saturation levels of the amplifier). The specified performance may be achieved in all cases by applying the methodology described herein. By first calculating the Minimum Required Span to achieve the required resolution in all scenarios and then determining if the remaining dynamic range or headroom is large enough to accommodate the sources of variation, the methodology determines if the resolution requirement is feasible. If the sources of variation are too large, the resolution requirement may not be attainable. In such a case, the resolution requirement should be relaxed, or the sources of variation must be decreased. Finally, once the system is successfully designed to ensure that the sensor signal will always be within the dynamic range of the amplifier (and high and low reference voltages of the A/D), a software calibration may be implemented to nullify any room temperature device-to-device and component variations. 3-354 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1571 Digital Blood Pressure Meter Prepared by: C.S. Chua and Siew Mun Hin Sensor Application Engineering Singapore, A/P blood pressure (SBP) and diastolic blood pressure (DBP) are obtained by identifying the region where there is a rapid increase then decrease in the amplitude of the pulses respectively. Mean arterial pressure (MAP) is located at the point of maximum oscillation. This application note describes a Digital Blood Pressure Meter concept which uses an integrated pressure sensor, analog signal-conditioning circuitry, microcontroller hardware/software and a liquid crystal display. The sensing system reads the cuff pressure (CP) and extracts the pulses for analysis and determination of systolic and diastolic pressure. This design uses a 50 kPa integrated pressure sensor (Motorola P/N: MPXV5050GP) yielding a pressure range of 0 mmHg to 300 mmHg. HARDWARE DESCRIPTION AND OPERATION The cuff pressure is sensed by Motorola's integrated pressure X-ducer. The output of the sensor is split into two paths for two different purposes. One is used as the cuff pressure while the other is further processed by a circuit. Since MPXV5050GP is signal-conditioned by its internal op-amp, the cuff pressure can be directly interfaced with an analog-to-digital (A/D) converter for digitization. The other path will filter and amplify the raw CP signal to extract an amplified version of the CP oscillations, which are caused by the expansion of the subject's arm each time pressure in the arm increases during cardiac systole. The output of the sensor consists of two signals; the oscillation signal ( 1 Hz) riding on the CP signal ( 0.04 Hz). Hence, a 2-pole high pass filter is designed to block the CP signal before the amplification of the oscillation signal. If the CP signal is not properly attenuated, the baseline of the oscillation will not be constant and the amplitude of each oscillation will not have the same reference for comparison. Figure 1 shows the oscillation signal amplifier together with the filter. CONCEPT OF OSCILLOMETRIC METHOD This method is employed by the majority of automated non-invasive devices. A limb and its vasculature are compressed by an encircling, inflatable compression cuff. The blood pressure reading for systolic and diastolic blood pressure values are read at the parameter identification point. The simplified measurement principle of the oscillometric method is a measurement of the amplitude of pressure change in the cuff as the cuff is inflated from above the systolic pressure. The amplitude suddenly grows larger as the pulse breaks through the occlusion. This is very close to systolic pressure. As the cuff pressure is further reduced, the pulsation increase in amplitude, reaches a maximum and then diminishes rapidly. The index of diastolic pressure is taken where this rapid transition begins. Therefore, the systolic +DC offset C2 3 0.33u + 1 LM324N - 4 2 U1a Vo 11 1M R3 +5V Vi R2 R1 1k 33u 150k C1 Freescale Semiconductor, Inc... INTRODUCTION Figure 1. Oscillation Signal Amplifier Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-355 Freescale Semiconductor, Inc. AN1571 The filter consists of two RC networks which determine two cut-off frequencies. These two poles are carefully chosen to ensure that the oscillation signal is not distorted or lost. The two cut-off frequencies can be approximated by the following equations. Figure 2 describes the frequency response of the filter. This plot does not include the gain of the amplifier. fP1 = 1 2pR1C1 fP2 = 1 2pR3C2 10 -10 -20 Attenuation (dB) Freescale Semiconductor, Inc... 0 Oscillation Signal (1 Hz) -30 -40 -50 CP Signal (0.04 Hz) -60 -70 -80 0.01 0.1 1 10 100 Frequency (Hz) Figure 2. Filter Frequency Response 3-356 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. The oscillation signal varies from person to person. In general, it varies from less than 1 mmHg to 3 mmHg. From the transfer function of MPXV5050GP, this will translate to a voltage output of 12 mV to 36 mV signal. Since the filter gives an attenuation of 10 dB to the 1 Hz signal, the oscillation signal becomes 3.8 mV to 11.4 mV respectively. Experiments AN1571 indicate that, the amplification factor of the amplifier is chosen to be 150 so that the amplified oscillation signal is within the output limit of the amplifier (5 mV to 3.5 V). Figure 3(a) shows the output from the pressure sensor and Figure 3(b) shows the extracted oscillation signal at the output of the amplifier. 3 2.5 1.5 Oscillation signal is extracted here 1 0.5 0 0 5 10 15 20 Time (seconds) 25 30 35 40 Figure 3. CP signal at the output of the pressure sensor 3.5 MAP 3 SBP DBP 2.5 2 Vo (volts) Freescale Semiconductor, Inc... Vi (volts) 2 1.5 1 0.5 0 10 15 20 25 30 35 Time (seconds) Figure 3b. Extracted oscillation signal at the output of amplifier Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-357 AN1571 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Referring to the schematic, Figure 4, the MPX5050GP pressure sensor is connected to PORT D bit 5 and the output of the amplifier is connected to PORT D bit 6 of the microcontroller. This port is an input to the on-chip 8-bit analog-to-digital (A/D) converter. The pressure sensor provides a signal output to the microprocessor of approximately 0.2 Vdc at 0 mmHg to 4.7 Vdc at 375 mmHg of applied pressure whereas the amplifier provides a signal from 0.005 V to 3.5 V. In order to maximize the resolution, separate voltage references should be provided for the A/D instead of using the 5 V supply. In this example, the input range of the A/D converter is set at approximately 0 Vdc to 3.8 Vdc. This compresses the range of the A/D converter around 0 mmHg to 300 mmHg to maximize the resolution; 0 to 255 counts is the range of the A/D converter. VRH and VRL are the reference voltage inputs to the A/D converter. The resolution is defined by the following: Count = [(VXdcr - VRL)/(VRH - VRL)] x 255 The count at 0 mmHg = [(0.2 - 0)/(3.8 - 0)] x 255 14 The count at 300 mmHg = [(3.8 - 0)/(3.8 - 0)] x 255 255 Therefore the resolution = 255 - 14 = 241 counts. This translates to a system that will resolve to 1.24 mmHg. The voltage divider consisting of R5 and R6 is connected to the +5 volts powering the system. The output of the pressure sensor is ratiometric to the voltage applied to it. The pressure sensor and the voltage divider are connected to a common supply; this yields a system that is ratiometric. By nature of this 3-358 ratiometric system, variations in the voltage of the power supplied to the system will have no effect on the system accuracy. The liquid crystal display (LCD) is directly driven from I/O ports A, B, and C on the microcontroller. The operation of a LCD requires that the data and backplane (BP) pins must be driven by an alternating signal. This function is provided by a software routine that toggles the data and backplane at approximately a 30 Hz rate. Other than the LCD, there are two more I/O devices that are connected to the pulse length converter (PLM) of the microcontroller; a buzzer and a light emitting diode (LED). The buzzer, which connected to the PLMA, can produce two different frequencies; 122 Hz and 1.953 kHz tones. For instance when the microcontroller encounters certain error due to improper inflation of cuff, a low frequency tone is alarm. In those instance when the measurement is successful, a high frequency pulsation tone will be heard. Hence, different musical tone can be produced to differential each condition. In addition, the LED is used to indicate the presence of a heart beat during the measurement. The microcontroller section of the system requires certain support hardware to allow it to function. The MC34064P-5 provides an undervoltage sense function which is used to reset the microprocessor at system power-up. The 4 MHz crystal provides the external portion of the oscillator function for clocking the microcontroller and provides a stable base for time based functions, for instance calculation of pulse rate. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data +5V C5 0.33u Vout 1 Pressure Sensor MPXV5050GP GND Vs 3 2 0.33u C2 2 R4 GND Output R0 3 Input 24k +5V 1 +5V 2 3 +5V LM324N R2 150k 1 Buzzer 100n C7 R8 1k 1M MC78L05ACP LED C6 330u 100R 100u C3 VDD OSC2 22p PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 14 13 12 11 9 5 4 3 +5V MC68HC05B16CFN PD0/AN0 PD1/AN1 PD2/AN2 PD3/AN3 PD4/AN4 PD5/AN5 PD6/AN6 PD7/AN7 PA0 PA1 PA2 PA3 PA4 PA5 PA6 PA7 VRH VRL RD TCAP1 TCAP2 /RESET /IRQ OSC1 22p 20 PLMA 21 PLMB 49 PC0 48 PC1 47 PC2/ECLK 46 PC3 45 PC4 44 PC5 43 PC6 42 PC7 52 TDO 51 SCLK 2 TCMP1 1 TCMP2 10 17 X1 4MHz 10M R10 C4 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 8 7 50 22 23 18 19 16 +5V +5V +5V 1 Reset +5V GND Input 2 5V Regulator 10k R1 C1 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 33u 11 4 R5 R6 R9 4.7k + 36R 15k Motorola Sensor Device Data 3 C8 R3 9V Battery Freescale Semiconductor, Inc... MC34064 DP1 4 F2 G2 DP2 DP 14 D2 13 E2 25 A2 D 24 B2 15 C2 26 27 12 DP G B C E L 1 2 L LCD5657 C1 DP 18 D1 17 E1 3 19 G1 22 F1 21 A1 20 B1 23 16 F A E3 D3 C3 B3 A3 F3 G3 DP3 BP BP L 9 10 11 29 30 31 32 8 1 40 28 37 G4 36 F4 35 A4 34 B4 7 C4 6 D4 E4 5 Freescale Semiconductor, Inc. AN1571 Figure 4. Blood Pressure Meter Schematic Drawing 3-359 4.7k Freescale Semiconductor, Inc. AN1571 SOFTWARE DESCRIPTION Upon system power-up, the user needs to manually pump the cuff pressure to approximately 160 mmHg or 30 mmHg above the previous SBP. During the pumping of the inflation bulb, the microcontroller ignores the signal at the output of the amplifier. When the subroutine TAKE senses a decrease in CP for a continuous duration of more than 0.75 seconds, the microcontroller will then assume that the user is no longer pumping the bulb and starts to analyze the oscillation signal. Figure 5 shows zoom-in view of a pulse. Freescale Semiconductor, Inc... 1.75 Vo (volt) 450 ms Premature pulse -8.5 -8.3 -8.1 -7.9 -7.7 -7.5 -7.3 -7.1 Time (second) Figure 5. Zoom-in view of a pulse First of all, the threshold level of a valid pulse is set to be 1.75 V to eliminate noise or spike. As soon as the amplitude of a pulse is identified, the microcontroller will ignore the signal for 450 ms to prevent any false identification due to the presence of premature pulse "overshoot" due to oscillation. Hence, this algorithm can only detect pulse rate which is less than 133 beats per minute. Next, the amplitudes of all the pulses detected are stored in the RAM for further analysis. If the microcontroller senses a non-typical oscillation envelope 3-360 shape, an error message ("Err") is output to the LCD. The user will have to exhaust all the pressure in the cuff before re-pumping the CP to the next higher value. The algorithm ensures that the user exhausts all the air present in the cuff before allowing any re-pumping. Otherwise, the venous blood trapped in the distal arm may affect the next measurement. Therefore, the user has to reduce the pressure in the cuff as soon as possible in order for the arm to recover. Figure 6 is a flowchart for the program that controls the system. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1571 MAIN PROGRAM Initialization Clear I/O ports Display "CAL" and output a musical tone Clear all the variables Freescale Semiconductor, Inc... Take in the amplitude of all the oscillation signal when the user has stop pumping Repump? Y N Calculate the SBP and DBP and also the pulse rate Output a high frequency musical tone Display pulse rate. Display "SYS" follow by SBP. Display "dlA" follow by DBP. Y Is there any error in the calculation or the amplitude envelope detected? N N Y Display "Err" N Exhaust cuff before repump Output a low frequency alarm Exhaust cuff before repump Y Figure 6. Main program flowchart Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-361 AN1571 Freescale Semiconductor, Inc. SELECTION OF MICROCONTROLLER CONCLUSION Although the microcontroller used in this project is MC68HC05B16, a smaller ROM version microcontroller can also be used. The table below shows the requirement of microcontroller for this blood pressure meter design in this project. This circuit design concept may be used to evaluate Motorola pressure sensors used in the digital blood pressure meter. This basic circuit may be easily modified to provide suitable output signal level. The software may also be easily modified to provide better analysis of the SBP and DBP of a person. AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAA Table 1. Selection of microcontroller On-chip ROM space 2 kilobytes On-chip RAM space 150 bytes 2-channel A/D converter (min.) REFERENCES Lucas, Bill (1991). "An Evaluation System for Direct Interface of the MPX5100 Pressure Sensor with a Microprocessor," Motorola Application Note AN1305. 16-bit free running counter timer LCD driver Freescale Semiconductor, Inc... On-chip EEPROM space 32 bytes Power saving Stop and Wait modes 3-362 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Understanding Pressure and Pressure Measurement AN1573 Prepared by: David Heeley Systems and Applications Engineering Motorola Semiconductor Products Sector Sensor Products Division Phoenix, Arizona Freescale Semiconductor, Inc... Introduction Fluid systems, pressure and pressure measurements are extremely complex. The typical college curriculum for Mechanical Engineers includes at least two semesters in fluid mechanics. This paper will define and explain the basic concepts of fluid mechanics in terms that are easily understood while maintaining the necessary technical accuracy and level of detail. Pressure and Pressure Measurement What is fluid pressure? Fluid pressure can be defined as the measure of force per-unit-area exerted by a fluid, acting perpendicularly to any surface it contacts (a fluid can be either a gas or a liquid, fluid and liquid are not synonymous). The standard SI unit for pressure measurement is the Pascal (Pa) which is equivalent to one Newton per square meter (N/m2) or the KiloPascal (kPa) where 1 kPa = 1000 Pa. In the English system, pressure is usually expressed in pounds per square inch (psi). Pressure can be expressed in many different units including in terms of a height of a column of liquid. The table below lists commonly used units of pressure measurement and the conversion between the units. kPa mm Hg millibar in H2O PSI 1 atm 101.325 760.000 1013.25 406.795 14.6960 1 kPa 1.000 7.50062 10.000 4.01475 0.145038 1 mm Hg 0.133322 1.000 1.33322 0.535257 0.0193368 1 millibar 0.1000 0.750062 1.000 0.401475 0.0145038 1 in H2O 0.249081 1.86826 2.49081 1.000 0.0361 1 PSI 6.89473 51.7148 68.9473 27.6807 1.000 0.07355 9.8 x 10-8 0.03937 0.0014223 1 mm H2O 0.009806 Figure 1. Conversion Table for Common Units of Pressure Pressure measurements can be divided into three different categories: absolute pressure, gage pressure and differential pressure. Absolute pressure refers to the absolute value of the force per-unit-area exerted on a surface by a fluid. Therefore the absolute pressure is the difference between the pressure at a given point in a fluid and the absolute zero of pressure or a perfect vacuum. Gage pressure is the measurement of the difference between the absolute pressure and the local atmospheric pressure. Local atmospheric pressure can vary depending on ambient temperature, altitude and local weather conditions. The U.S. standard atmospheric pressure at sea level and 59F (20C) is 14.696 pounds per square inch absolute (psia) or 101.325 kPa absolute (abs). When referring to pressure measurement, it is critical to specify what reference the pressure is related to. In the English system of units, measurement relating the pressure to a reference is accomplished by specifying pressure in terms of pounds per square inch absolute (psia) or pounds per square inch gage (psig). For other units of measure it is important to specify gage or absolute. The abbreviation `abs' refers to an absolute measurement. A gage pressure by convention is always positive. A `negative' gage pressure is defined as vacuum. Vacuum is the measurement of the amount by which the local atmospheric pressure exceeds the absolute pressure. A perfect vacuum is zero absolute pressure. Figure 2 shows the relationship between absolute, gage pressure and vacuum. Differential pressure is simply the measurement of one unknown pressure with reference to another unknown pressure. The pressure measured is the difference between the two unknown pressures. This type of pressure measurement is commonly used to measure the pressure drop in a fluid system. Since a differential pressure is a measure of one pressure referenced to another, it is not necessary to specify a pressure reference. For the English system of units this could simply be psi and for the SI system it could be kPa. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-363 Freescale Semiconductor, Inc. AN1573 Pressure Local Atmospheric Pressure Gage Absolute Vacuum (Negative Gage) Atmospheric Freescale Semiconductor, Inc... Absolute Figure 2. Pressure Term Relationships In addition to the three types of pressure measurement, there are different types of fluid systems and fluid pressures. There are two types of fluid systems; static systems and dynamic systems. As the names imply, a static system is one in which the fluid is at rest and a dynamic system is on in which the fluid is moving. Static Pressure Systems The pressure measured in a static system is static pressure. In the pressure system shown in Figure 3, a uniform static fluid is continuously distributed with the pressure varying only with vertical distance. The pressure is the same at all points along the same horizontal plane in the fluid and is independent of the shape of the container. The pressure increases with depth in the fluid and acts equally in all directions. The increase in pressure at a deeper depth is essentially the effect of the weight of the fluid above that depth. Figure 4 shows two containers with the same fluid exposed to the same external pressure - P . At any equal depth within either tank the pressure will be the same . Note that the sides of the large tank are not vertical. The pressure is dependent only on depth and has nothing to do with the shape of the container. If the working fluid is a gas, the pressure increase in the fluid due to the height of the fluid is in most cases negligible since the density and therefore the weight of the fluid is much smaller than the pressure being applied to the system. However, this may not remain true if the system is large enough or the pressures low enough. One example considers how atmospheric pressure changes with altitude. At sea level the standard U.S. atmospheric pressure is 14.696 psia (101.325 kPa). At an altitude of 10,000 ft (3048 m) above sea level the standard U.S. atmospheric pressure is 10.106 psia (69.698 kPA) and at 30,000 ft (9144 m), the standard U.S. atmospheric pressure is 4.365 psia (30.101 kPa). The pressure in a static liquid can be easily calculated if the density of the liquid is known. The absolute pressure at a depth H in a liquid is defined as: Pabs = P + ( x g x H) Where : Pabs is the absolute pressure at depth H. P is the external pressure at the top of the liquid. For most open systems this will be atmospheric pressure. is the density of the fluid. g is the acceleration due to gravity (g = 32.174 ft/sec2 (9.81 m/sec2)). H is the depth at which the pressure is desired. 3-364 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. H IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIII AN1573 Figure 3. Continuous Fluid System Freescale Semiconductor, Inc... P P IIIIIIIIIIIIIII III IIIIIIIIIIIIIII HIII IIIIIIIIIIIIIII III IIIIIIIIIIIIIII III IIIIIIIIIIIIIII III IIIIIIIIIIIIIII III IIIIIIIIIIIIIII III Figure 4. Pressure Measurement at a Depth in a Liquid Dynamic Pressure Systems Dynamic pressure systems are more complex than static systems and can be more difficult to measure. In a dynamic system, pressure typically is defined using three different terms. The first pressure we can measure is static pressure. This pressure is the same as the static pressure that is measured in a static system. Static pressure is independent of the fluid movement or flow. As with a static system the static pressure acts equally in all directions. The second type of pressure is what is referred to as the dynamic pressure. This pressure term is associated with the velocity or the flow of the fluid. The third pressure is total pressure and is simply the static pressure plus the dynamic pressure. Steady-State Dynamic Systems Care must be taken when measuring dynamic system pressures. For a dynamic system, under steady-state conditions, accurate static pressures may be measured by tapping into the fluid stream perpendicular to the fluid flow. For a dynamic system, steady-state conditions are defined as no change in the system flow conditions: pressure, flow rate, etc. Figure 5 illustrates a dynamic system with a fluid flowing through a pipe or duct. In this example a static pressure tap is located in the duct wall at point A. The tube inserted into the flow is called a Pitot tube. The Pitot tube measures the total pressure at point B in the system. The total pressure measured at this point is referred to as the stagnation pressure. The stagnation pressure is the value obtained when a flowing fluid is decelerated to zero velocity in an isentropic (frictionless) process. This process converts all of the energy from the flowing fluid into a pressure that can be measured. The stagnation or total pressure is the static pressure plus the dynamic pressure. It is very difficult to accurately measure dynamic pressures. When dynamic pressure measurement is desired, the total and static pressures are measured and then subtracted to obtain the dynamic pressure. Dynamic pressures can be used to determine the fluid velocities and flow rates in dynamic systems. When measuring dynamic system pressures, care must be taken to ensure accuracy. For static pressure measurements, the pressure tap location should be chosen so that the measurement is not influenced by the fluid flow. Typically, taps are located perpendicular to the flow field. In Figure 5, the static pressure tap at point A is in the wall of the duct and perpendicular to the flow field. In Figures 6a and 6c the static taps (point A) in the pressure probes are also perpendicular to the flow field. These examples show the most common type of static pressure taps, however there are many different static pressure tap options. For total or stagnation pressure measurements, it is important that the Pitot or impact tube be aligned parallel to the flow field with the tip of the tube pointing directly into the flow. In Figures 6b and 6c, the Pitot tube is aligned parallel with the flow, with the tube opening pointing directly into the flow. Although the static pressure is independent of direction, the dynamic pressure is a vector quantity which depends on both magnitude and direction for the total measured value. If the Pitot tube is misaligned with the flow, accuracy of the total pressure measurement may suffer. In addition, for accurate pressure measurements the pressure tap holes and probes must be smooth and free from any burrs or obstructions that could cause disturbances in the flow. The location of the pressure taps and probes, static and total, must also be selected carefully. Any location in the system where the flow field may be disturbed Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-365 Freescale Semiconductor, Inc. AN1573 Freescale Semiconductor, Inc... should be avoided, both upstream and downstream. These locations include any obstruction or change such as valves, elbows, flow splits, pumps, fans, etc. To increase the accuracy of pressure measurement in a dynamic system, allow at least 10 pipe / duct diameters downstream of any change or obstruction and at least 2 pipe / duct diameters upstream. In addition the pipe / duct diameter should be much larger than the diameter of the Pitot tube. The pipe / duct diameter should be at least 30 times the Pitot tube diameter. Flow straighteners can also be used to minimize any variations in the direction of the flow. Also, when using a Pitot tube, it is recommended that the static pressure tap be aligned in the same plane as the total pressure tap. On the Pitot-static tube, the difference in location is assumed to be negligible. Flow-through pipes and ducts will result in a velocity field and dynamic pressure field that are non-uniform. At the wall of any duct or pipe there exists a no-slip boundary due to friction. This means that at the wall itself the velocity of the fluid is zero. Figure 5 shows an imaginary velocity distribution in a duct. The shape of the distribution will depend on the fluid conditions, system flow and pressure. In order to accurately determine the average dynamic pressure across a duct section, a series of total pressure readings must be taken across the duct. These pressure measurements should be taken at different radii and clock positions across the cross section of a round duct or at various width and height locations for a rectangular duct. Once this characterization has been performed for the duct , a correlation can be easily made between the total pressure measurement at the center of the duct relative to the average duct total pressure. This technique is also used to determine the velocity profile within the duct. B Velocity Distribution Pitot Tube A Static Pressure Tap Figure 5. Static and Total Pressure Measurements Within a Dynamic Fluid System. B Flow B Flow Flow A A Ps Ps (A) Static Pressure Probe Po (B) Total Pressure Pitot Tube Po (C) Combination Static Pressure and Total Pressure Pitot Tube (Pitot-Static Tube) Figure 6. Types of Pressure Probes 3-366 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1573 Freescale Semiconductor, Inc... Transient Systems Transient systems are systems with changing conditions such as pressures, flow rates, etc. Measurements in transient systems are the most difficult to accurately obtain. If the measurement system being used to measure the pressure has a faster response time than the rate of change in the system, then the system can be treated as quasi-steady-state. That is, the measurements will be about as accurate as those taken in the steady-state system. If the measurement of the system is assumed to be a snap shot of what is happening in the system, then you want to be able to take the picture faster than the rate of change in the system or the picture will be blurred. In other words, the measurement results will not be accurate. In a pressure measurement system, there are two factors that determine the overall measurement response: (1) the response of the transducer element that senses the pressure, and (2) the response of the interface between the transducer and the pressure system such as the pressure transmitting fluid and the connecting tube, etc. For Motorola pressure sensors, the second factor usually determines the overall frequency response of the pressure measurement system. The vast majority of pressure systems that require measurements today are quasi-steady-state systems where system conditions are changing relatively slowly compared to the response rate of the measurement system or the change happens instantaneously and then stabilizes. Two transient system examples include washing machines and ventilation ducts in buildings. In a washing machine, the height of the water in the tub is measured indirectly by measuring the pressure at the bottom of the tub. As the tub fills the pressure changes. The rate at which the tub fills and the pressure changes is much slower than the response rate of the measurement system. In a ventilation duct, the pressure changes as the duct registers are opened and closed, adjusting the air movement within the building. As more registers are opened and closed, the system pressure changes. The pressure changes are virtually instantaneous. In this case, pressure changes are essentially incremental and therefore easy to measure accurately except at the instant of the change. For most industrial and building control applications, the lag in the pressure measurement system is negligible. As the control or measurement system becomes more precise, the frequency response of the measurement system must be considered. Motorola Pressure Sensors This application note has covered various types of pressures that are measured and how to tap into a system to measure the desired pressures. How are the actual pressure measurements made? There are many types of pressure measurement systems ranging from simple liquid tube manometers to bourdon-tube type gages to piezo-electric silicon based transducers. Today, as electronic control and measurement systems are replacing mechanical systems, silicon-based pressure transducers and sensors are becoming the sensors of choice. Silicon micromachined sensors offer very high accuracies at very low cost and provide an interface between the mechanical world and the electrical system. Motorola carries a complete line of silicon based pressure sensors which feature a wide range of pressures with various levels of integration on a single chip. These levels of integration start with the basic uncompensated, uncalibrated pressure sensor all the way to the fully integrated, temperature compensated, calibrated and signal conditioned pressure sensors. The response time of Motorola's MPX series silicon pressure sensors is typically 1 millisecond or less. For static or dynamic systems, Motorola's pressure sensors are an excellent solution for pressure measurement systems. Conclusion Pressures and pressure measurements can be extremely complex and complicated. However, for most systems it is relatively easy to obtain accurate pressure measurements if the proper techniques are used. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-367 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Designing a Homemade Digital Output for Analog Voltage Output Sensors AN1586 Freescale Semiconductor, Inc... by: Eric Jacobsen Systems and Applications Engineer Sensor Products Division Motorola, Inc. following discussions will pertain specifically to semiconductor pressure sensors. The digital output sensor in Figure 1. consists of the following: A digital output is more desirable than an analog output in noisy environments (e.g. automotive, washing machines, etc.) and remote sensing applications (building controls, industrial applications, etc.) because a digital signal inherently has better noise immunity compared to analog signals. Additional applications requiring a sensor with a digital output include microcontroller-based systems that have no A/D in the system or that have no A/D channels available for the sensing function. For these applications, there is no other option but a digital output to further process the signal. Via a design example this paper shows how to easily convert an analog voltage output sensor to a digital output sensor. For the design example, each of the required circuit components is discussed in detail. While the design is applicable to analog voltage output sensors (differential or single-ended output) in general, the design example and * Motorola MPX2000 series pressure sensor * A two op amp gain stage to amplify the sensor's signal * An integrator (i.e. a low pass filter consisting of one resistor and one capacitor) * An LM311 comparator * An MC68HC05P9 microcontroller with which only two pins are used: the output compare timer channel (TCMP) and one general I/O pin (the input capture timer channel, TCAP, can be used in place of the general I/O pin). Since only two of the MC68HC05P9's pins are used, the remaining pins are available for other system functions. INTEGRATOR R5 FROM MC68HC05P9's TCMP PIN C1 AMPLIFIER +5 V +5 V R4 R2 R+SHIFT1 R1 R3 - + R+SHIFT2 X1 MPX2000 SERIES +5 V 4 3 +5 V +5 V U1 MC33272 - + - + U1 MC33272 U2 LM311 RH (OPTIONAL) R6 TO MC68HC05P9's GENERAL I/O PIN OR TCAP PIN COMPARATOR 2 1 PRESSURE SENSOR 3-368 Figure 1. The Digital Output Sensor Schematic www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. After the discussion of the circuit components, the following system-related issues will be discussed simultaneously using the design example: * How the system works * Defining and designing the digital output for a desired signal resolution * A step-by-step procedure that shows you how to digitize the signal * A procedure to show you how to software calibrate the digital output * Related software examples Freescale Semiconductor, Inc... This system, in addition to the benefits of a digital output (noise immunity, etc.), also has the following additional inherent benefits. These benefits will be addressed in more detail in the systems topics. * The circuit topology and method of "digitizing" the sensor's analog output is very stable and accurate. The system uses the microcontroller's precise, internal, digital time base to digitize the analog signal. then signal conditioned (amplified and level shifted) to provide a four volt span with a zero pressure offset of 0.5 V. Table 1. MPX2100 Electrical Characteristics for VS = 10 V, TA = 25C Characteristic Symbol Min Pressure Range Pop 0 Supply Voltage VS Full Scale Span VFSS 38.5 Voff -1.0 Zero Pressure Offset V/P Sensitivity Linearity * The software required to digitize the signal requires very little CPU time and overhead. * The required circuitry is minimal, simple, and cost-effective. THE PRESSURE SENSOR Motorola's MPX2000 series sensors are temperature compensated and calibrated (i.e. offset and span are precision trimmed) pressure transducers. These sensors are available in full scale pressure ranges from 10 kPa (1.5 psi) to 700 kPa (100 psi). Although the specifications (see Table 1) in the data sheets apply to a 10 V supply voltage, the output of these devices is ratiometric with the supply voltage. For example, at the absolute maximum supply voltage rating, 16 V, the sensor will typically produce a differential output voltage of 64 mV at the rated full scale pressure of the given sensor. One exception to this is that the span of the MPX2010 (10 kPa sensor) will be only 40 mV due to the device's slightly lower sensitivity. Since the maximum supply voltage produces the largest output signal, it is evident that even the best case scenario will require some signal conditioning to obtain a usable signal (input to an A/D, etc.). For this specific design, an MPX2100 and 5.0 V supply are used, yielding a typical maximum sensor output of 20 mV (typical zero pressure offset is 0.0 mV and typical span is 20 mV). The sensor's output is Motorola Sensor Device Data Typ Max Unit 100 kPa 10 16 Vdc 40 41.5 mV 1.0 mV 0.4 mV/kPa -- -0.25 0.25 %VFSS Temperature Effect on Span TCVFSS -1.0 1.0 %VFSS Temperature Effect on Offset TCVoff -1.0 1.0 mV * The signal resolution is user-programmable via software -- i.e. the user can program whether the resolution is 8-bit, 10-bit, etc. * The digital output is calibrated in software so that component tolerances can be nullified. AN1586 AMPLIFIER STAGE The amplifier circuitry, shown in Figure 1. , is composed of two op amps. This interface circuit has a much lower component count than conventional quad op amp instrumentation amplifiers. The two op amp design offers the high input impedance, low output impedance, and high gain desired for a transducer interface, while performing a differential to single-ended conversion. The amplifier incorporates level shifting capability. The amplifier has the following transfer function: Vo + 1 ) R4 R3 * (Vsensor) + V + shift ) where R1 = R4, R2 = R3, the gain is 1 R4, Vsensor is the R3 sensor's differential output (S+ - S-), and V+shift is the positive dc level shift voltage created by the resistor divider comprised of R+shift1 and R+shift2. V+shift is used to position the zero pressure offset at the desired level. Table 2 summarizes the 1% resistor values used to obtain a four volt span with a zero pressure offset of 0.5 V (assuming the typical sensor offset and span values of 0.0 mV and 20 mV, respectively). Table 2. Resistor Values for the MPX2100 Amplifier Design R+shift1 R+shift2 R1 R2 R3 R4 4.99 k 549 20.0 k 100 100 20.0 k www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-369 Freescale Semiconductor, Inc. AN1586 THE INTEGRATOR As shown in Figure 1. , the integrator consists of a single resistor and single capacitor. A programmable duty cycle pulse train from the microcontroller is input to the integrator. Assuming that the RC time constant of the integrator is sufficiently long compared to the pulse train's frequency, the resulting output which is input to the inverting terminal of the comparator is a dc voltage that is linearly proportional to the pulse train's duty cycle, i.e.: DC Output Voltage = Pulse Train's Duty Cycle (%) * 5 V Freescale Semiconductor, Inc... Where the Pulse Train's Duty Cycle is multiplied by the pulse train's logic-level one voltage value which is typically the same voltage as the microcontroller's 5 V supply. Table 3 shows a few examples of Pulse Train Duty Cycles and the corresponding DC Output Voltage assuming a typical pulse train logic-level one value of 5 V. Table 3. Example Pulse Train Duty Cycles and the Integrator's Corresponding dc Voltage Output Pulse Train's Duty Cycle (%) 0 25 50 75 100 DC Output Voltage (V) 0 1.25 2.5 3.75 5 To establish a stable constant dc voltage at the integrator's output, its time constant must be sufficiently long compared to the frequency of the pulse train. However, the system resolution and thus performance are directly related to the pulse train's frequency. The design of the time constant and choice of the resistor and capacitor values is discussed in System Design: Defining and designing for a desired signal resolution. COMPARATOR The LM311 chip is designed specifically for use as a comparator and thus has short delay times, high slew rate, and an open-collector output. A pull-up resistor (R6 = 5 k) at the output is all that is needed to obtain a rail-to-rail output. As Figure 1. shows, the pressure sensor's amplified output voltage is input to the non-inverting terminal of the op amp and the integrator's dc output voltage is input to the inverting terminal. Therefore, when the pressure sensor's output voltage is greater than the integrator's dc output voltage, the comparator's output is high (logic-level one); conversely, when the pressure sensor's output voltage is less than the integrator's dc output voltage, the comparator's output is low (logic-level zero). An optional resistor, RH is used as positive feedback around U2 in Figure 1 to provide a small amount of hysteresis to ensure a clean logic-level transition (prevents multiple transitions (squegging)) when the comparator's inputs are similar in value. The amount of hysteresis increases as the value of RH decreases. For this design, the value of RH is not critical but should be on the order of 100 k. THE MC68HC05P9 MICROCONTROLLER The microcontroller for this application requires an output compare timer channel and one general I/O pin. The output compare pin is programmed to output the pulse train that is input to the integrator, and the general I/O pin is configured as an input to monitor the logic-level of the comparator's output. 3-370 The remainder of this paper discusses the system and software requirements. SYSTEM DESIGN: HOW THE SYSTEM WORKS For any analog sensor voltage output, there's a pulse train with a duty cycle that when integrated will equal the sensor's output. Therefore, by incrementing via software the pulse train's duty cycle from 0% to 100%, there's a duty cycle that when integrated will be larger than the sensor's current voltage output. When the integrated pulse train voltage becomes larger than the sensor's output voltage, the comparator's output will change from a logic-level one to a logic-level zero. This logic-level, in turn, is monitored on the general I/O pin. The pulse train's duty cycle creating the integrated voltage that caused the comparator's logic-level transition is the digital representation of the sensor's voltage. Thus every sensor analog output voltage is mapped to a specific duty cycle. This design inherently has outstanding performance (very stable and accurate) since the digital representation of the sensor signal is created by the microcontroller's digital time base. Also the pressure measurement, made via software that first increments the pulse train's duty cycle and then determines if an edge transition occurred on the general I/O pin, is straightforward and easy. In a calibration routine (discussed below) the sensor's output at two known pressures (e.g. zero and full-scale pressure) can be mapped to two corresponding pulse train duty cycles. Since the pressure sensor's output voltage is linear with the applied pressure, and the integrator's dc output voltage is linear with the input pulse train duty cycle, then the pulse train's duty cycle that causes the logic-level transition at the comparator's output will also be linear with the applied pressure. Thus by knowing the duty cycles for two known pressures, a linear interpolation of any duty cycle gives an accurate measurement of the current pressure. The following equation is used to interpolate the pressure measurement where the pressure units are in kPa: Current Pressure = Current Duty Cycle - Duty Cycle @ Zero Pressure Duty Cycle @ Full-Scale Pressure - Duty Cycle @ Zero Pressure * Full-Scale Pressure in kPa For example: At zero pressure, if the pulse train's duty cycle required to cause a logic-level transition at the comparator's output is 25% and at full-scale pressure the pulse train's duty cycle is 75%, then the current pressure that corresponds to a duty cycle of 50% (required to obtain the logic-level one to logic-level zero transition at the comparator's output) is Current Pressure - 25% + 50% * 100 kPa = 50 kPa 75% - 25% Until now, the pulse train has been defined in terms of duty cycle. However, in practice duty cycle is calculated from the ratio of the high time to the total period of the pulse train. Therefore, there is a high time (typically in s) of the pulse train that causes the logic-level transition of the comparator's output. The interpolation of the current pressure can then be calculated directly from the high time of the pulse train that is programmed by the user to be generated by the www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. microcontroller's output compare pin. The equation is similar to the one above for Current Pressure: Freescale Semiconductor, Inc... Current Pressure = Current High Time - High Time @ Zero Pressure High Time @ Full-Scale Pressure - High Time @ Zero Pressure * Full-Scale Pressure in kPa Via this equation, the digital nature of the design is revealed. The analog voltage signal has been translated into a signal in the time domain where the high time generated by the output compare pin is actually the digital time representation of the sensor's output. Since the user precisely controls the high time of the pulse train (and period) via software which is based on the accurate digital time base of the microcontroller, the digital representation of the signal is very stable and accurate. Additionally, the high accuracy of the digital representation is possible since all the user must do to digitize the signal is detect a single logic-level transition at the comparator's output. SYSTEM DESIGN: DEFINING AND DESIGNING FOR A DESIRED SIGNAL RESOLUTION The resolution is directly related to the period (and thus frequency) of the pulse train. In our design, the difference between the pulse train's high time at full scale pressure and the pulse train's high time and zero pressure must be 512 s to obtain at least 8-bit resolution. This is determined by the fact that a 4 MHz crystal yields a 2 MHz clock speed in the MC68HC05P9 microcontroller. This, in turn, translates to 0.5 s per clock tick. There are four clock cycles per timer count. This results in 2 s per timer count. Thus, to obtain 256 timer counts (discrete high-time time intervals or 8-bit resolution), the difference between the zero pressure and full scale pressure high times must be at least 2 s x 256 = 512 s. To determine the pulse train's maximum frequency (or minimum period), the sensor's analog dynamic range (span) must be known. For this design, the span is 4 V. Thus the 4 V span of the sensor must translate to 512 s of time for 8-bit resolution. But the pulse train typically has a logic-level high AN1586 value of 5 V, indicating that for a 100% duty cycle or a period with all high time, the integrator's output would be 5 V; likewise for a duty cycle of 0% or a period with no high time, the output would be 0 V. Therefore 512 s accounts for only 4 V/5 V (80%) of the pulse train's total period. See Figure 2. . To calculate the pulse train's total period, divide the 512 s by 4/5 (0.8) to obtain the required minimum period for the pulse train of 640 s. The reciprocal of this minimum period is the maximum frequency (1.56 kHz) of the pulse train to obtain at least 8-bit resolution. To summarize: The MC68HC05P9 runs off a 4 MHz crystal. The microcontroller internally divides this frequency by two to yield an internal clock speed of 2 MHz. 1 2 MHz 0.5 ms +u clock cycle And, 4 clock cycles = 1 timer count. Therefore, 4 clock cycles 0.5 ms 2 ms * timer count clock cycle timer count + For 8-bit resolution, 2 ms * 256 timer counts = 512 s timer count which is the required minimum time into which the sensor's 4 V span is translated. To calculate the required period of the pulse train to yield the 0 to 5 V output (from 0% to 100% duty cycle based on the pulse train's logic-level high value of 5 V): Minimum Required Period = 512 ms for a 4 V sensor span 640 ms 4 5 of integrator s output Translating this to frequency, the maximum pulse train frequency is thus + 1 1.56 kHz. 640 ms The above procedure can be implemented easily for other resolution requirements (i.e. a resolution of 1%, 2%, etc.). 5 V (PULSE TRAIN'S LOGIC-LEVEL ONE VALUE) PULSE TRAIN HIGH TIME OF 640 ms (100% DUTY CYCLE) 4.5 V (SENSOR'S ANALOG VOLTAGE OUTPUT AT FULL-SCALE PRESSURE) PULSE TRAIN HIGH TIME OF 576 ms 4.0 V SPAN 0.5 V (SENSOR'S ANALOG VOLTAGE OUTPUT AT ZERO PRESSURE) 0 V (PULSE TRAIN'S LOGIC-LEVEL ZERO VALUE) + 512 ms FOR 8-BIT RESOLUTION PULSE TRAIN HIGH TIME OF 64 ms PULSE TRAIN HIGH TIME OF 0 ms (0% DUTY CYCLE) Figure 2. Designing the Pulse Train's Period for 8-Bit Resolution Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-371 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1586 Important Note: Very small and very large high times (assuming a fixed period) are typically unattainable due to the finite amount of time it takes to generate the pulse train on the output compare pin. This amount of time will vary depending on the microcontroller's clock speed and the latency of the actual software routines implemented. Thus the sensor's analog voltage to which the integrator's dc voltage is compared must be within the possible ranges of voltages created by the integrator's input pulse train -- i.e. the sensor's zero pressure offset voltage must be greater than the smallest voltage created by the integrator (corresponding to the pulse train's smallest possible high time) and the sensor's full scale output voltage must be less than the largest voltage created by the integrator (corresponding to the pulse train's largest possible high time). After establishing the frequency of the pulse train, the RC time constant for the integrator can be determined and the resistor and capacitor value can be chosen. The RC time constant should be long compared to the period of the pulse train so that a stable dc voltage (very little ripple due to the capacitor's charging and discharging) is obtained at the output of the comparator. Follow these steps to design the RC time constant and integrator's component values. The design example's calculations are presented simultaneously. For the resolution desired, determine the number of volts (typically mV) that corresponds to the least significant bit (one timer count). For this design example, 8-bit resolution (256 timer counts) over the desired pressure sensor span corresponds to # of mV timer count Pressure Sensor Span (V) + Desired Number of Timer Counts 4 V + 15.6 mV + 256 timer counts timer count Therefore the stability of the integrator's output voltage should be less than 15.6 mV (least significant bit). Choosing an RC time constant that allows a ripple of approximately one-fourth of the least significant bit is sufficient (approximately 3.9 mV). The most ripple occurs at a 50% duty cycle pulse train. For this design the entire period is 640 s. 50% duty cycle indicates a high time (and low time) of 320 s. Furthermore, the capacitor should discharge no more than approximately 3.9 mV (defined as V) over the 320 s. The following equation is used to calculate the value for RC: V(t) = Vinitial - V = Pulse Train Logic-level one value * Duty Cycle * t e RC where Vinitial = Pulse Train Logic-level one value * Duty Cycle and V is the voltage discharge of the capacitor. Solving for RC: RC = - ln + t V(t) Pulse Train Logic-level one value * Duty Cycle 320 ms 2.5 V - 3.9 mV ln 5 V * 50% 3-372 + 0.205 s Finally, choose the values of the resistor and capacitor. A typical resistor value is on the order of a tens of k. The resistor's value can be higher (hundreds of k) but care must be taken to avoid increased thermal noise. For this design, the resistor value is chosen to be 49.9 k (1% resistor). The capacitor's value is readily calculated to be C 0.205 s + 4.1 mF + 49.9 kW Choose the values of the resistor and capacitor so that the actual time constant is equal to or greater than the calculated time constant. Note: Be aware that temperature variations can create errors in the system (thus reducing system performance); therefore, be sure to use low temperature coefficient resistors, capacitors, etc. SYSTEM DESIGN: STEP-BY-STEP PROCEDURE FOR PRESSURE MEASUREMENT AND CALIBRATION To measure pressure (note: there are other measurement algorithms that can be performed that in some cases may be more acceptable (see below, Additional notes)): 1. Start with a pulse train with the minimum high time feasible with the system's microcontroller. Pulse train should run at a frequency equal to or less than the frequency calculated above. 2. Make sure the general I/O pin's input is high (sensor's output voltage is greater than the integrator's output voltage). 3. Increment the high time of the pulse train by one timer count. 4. Check the general I/O pin to see if its input is low (sensor's output voltage has become less than the integrator's output voltage). 5. If the general I/O pin is reading a logic-level zero, store in memory the high time of the pulse train as the current pressure high time reading that created the logic-level transition in the comparator's output. 6. If the general I/O pin is reading a logic-level one, go back to step 3 and repeat. 7. Using the equation "Current Pressure = ......." shown above, calculate the current pressure (assuming the system has already been calibrated). 8. Repeat steps 1 through 7 for additional pressure measurements. To calibrate the system: At zero and full scale pressures, perform the above 8 step pressure measurement routine. Store the appropriate pulse train high times corresponding to zero and full scale pressure. These high times will be used to calculate the current pressure as mentioned in Step 7 above. SOFTWARE EXAMPLES TO GENERATE PULSE TRAIN ON OUTPUT COMPARE TIMER CHANNEL The following software examples are written in assembly language for the MC68HC05P9 (the code is applicable to any HC05 series microcontroller with TCMP pin). www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1586 * GENERATES THE PULSE TRAIN ON TCMP GEN LDA PERIODL * LOW BYTE OF THE PERIOD SUB HIGHTIMEL * LOW BYTE OF THE HIGHTIME STA LOWTIMEL * LOW BYTE OF THE LOWTIME LDA PERIODH * HIGH BYTE OF THE PERIOD SBC HIGHTIMEH * HIGH BYTE OF THE HIGHTIME STA LOWTIMEH * HIGH BYTE OF THE LOWTIME RTS Freescale Semiconductor, Inc... * INCREASE THE HIGH TIME (DUTY CYCLE) OF THE PULSE TRAIN INCPW LDA HIGHTIMEL ADD #$01 * INCREMENT PULSE WIDTH BY 2 s STA HIGHTIMEL LDA HIGHTIMEH ADC #$0 STA HIGHTIMEH RTS * DECREASE THE HIGH TIME (DUTY CYCLE) OF THE PULSE TRAIN DECPW LDA HIGHTIMEL SUB #$01 * DECREMENT PULSE WIDTH BY 2 s STA HIGHTIMEL LDA HIGHTIMEH SBC #$0 STA HIGHTIMEH JSR GEN RTS * INCREASE THE PERIOD (DECREASE FREQUENCY) OF THE PULSE TRAIN INCPER LDA PERIODL ADD #$05 * INCREMENT PERIOD BY 10 s STA PERIODL LDA PERIODH ADC #$0 * ADJUST HIGH BYTE OF PERIOD IF CARRY STA PERIODH JSR GEN RTS * DECREASE THE PERIOD (INCREASE FREQUENCY) OF THE PULSE TRAIN DECPER LDA PERIODL SUB #$05 * DECREMENT PERIOD BY 10 s STA PERIODL LDA PERIODH SBC #$0 * ADJUST HIGH BYTE OF PERIOD IF BORROW STA PERIODH JSR GEN RTS TIMER LDA LDA TSR TCMPL BRSET 0,TCR,ADDHIGH ADDLOW BSET LDA ADD TAX LDA ADC STA STX RTI ADDHIGH BCLR LDA ADD TAX LDA ADC STA STX RTI 0,TCR LOWTIMEL TCMPL * INTERRUPT SERVICE ROUTINE FOR TCMP * CLEAR OCF FLAG IN TSR * HIGH OR LOW PULSE TIME NEEDED? * ADD LOW TIME TO THE PULSE TRAIN TCMPH LOWTIMEH TCMPH TCMPL 0,TCR HIGHTIMEL TCMPL * ADD HIGH TIME TO THE PULSE TRAIN TCMPH HIGHTIMEH TCMPH TCMPL Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-373 AN1586 Freescale Semiconductor, Inc. ADDITIONAL NOTES pressure, etc. This is typically more convenient and eliminates the need to poll a general I/O pin every time the pulse train's high time is incremented (interrupt subroutine is executed only when the edge transition occurs). SUMMARY Shown above is a minimal component design that can convert an analog sensor's output into a digital output. Each major subsystem (sensor, amplifier, integrator, comparator, and microcontroller) is explained in detail simultaneously with a design example. Next the system operation is discussed including how it works and how to design a desired system resolution. Finally a flow chart for measuring and calibrating the sensor's output is presented. Freescale Semiconductor, Inc... This type of A/D conversion method (one type of A/D conversion) inherently takes a finite period of time to digitize the signal (incrementing the pulse train's high time while polling the general I/O pin); however, for most sensor applications the physical phenomenon being measured does not change quickly (<1 ms) enough to warrant an ultra-fast A/D conversion process. An additional advantage of this design is that the measurement process may be performed only as necessary, keeping the CPU processing time and overhead minimal. If an input capture timer channel (TCAP) is available, it may be configured to detect the logic-level one to logic-level zero transition of the comparator's output. When the edge transition occurs, an interrupt service routine is executed that stores the pulse train's high times, calculates the current 3-374 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1636 Implementing Auto Zero for Integrated Pressure Sensors Prepared by Ador Reodique Motorola Sensor Systems and Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION This application note describes how to implement an auto- zero function when using a Motorola integrated pressure sensor with a microcontroller and an analog to digital converter (MCU and an A/D). Auto-zero is a compensation technique based on sampling the offset of the sensor at reference pressure (atmospheric pressure is a zero reference for a gauge measurement) in order to correct the sensor output for long- term offset drift or variation. Sources of offset errors are due to device to device offset variation (trim errors), mechanical stresses (mounting stresses), shifts due to temperature and aging. Performing auto-zero will greatly reduce these errors. The amount of error correction is limited by the resolution of the A/D. In pressure sensing applications where a zero-pressure reference condition can exist, auto-zero can be implemented easily when an integrated pressure sensor is interfaced to an MCU. EFFECTS OF OFFSET ERRORS Figure 1 illustrates the transfer function of an integrated pressure sensor. It is expressed by the linear function: * P = (VOUT *VOFF)/S. If an offset error is introduced due to device to device variation, mechanical stresses, or offset shift due to temperature (the offset has a temperature coefficient or TCO), those errors will show up as an error, P, in the pressure reading: P + P = [VOUT *(VOFF + VOFF)]/S. As evident in Figure 2, offset errors, VOFF, have the effect of moving the intercept up and down without affecting the sensitivity. We can therefore correct this error by sampling the pressure at zero reference pressure (atmosphere) and subtracting this from the sensor output. * VOUT = VOFF + [(VFSO VOFF)/(PMAX PREF)]*P = VOFF + S*P. Here, VOUT is the voltage output of the sensor, VFSO is the full-scale output, VOFF is the offset, PMAX is the maximum pressure and PREF is the reference pressure. Note that (VFSO VOFF/PMAX PREF) can be thought of as the slope of the line and VOFF as they y-intercept. The slope is also referred to as the sensitivity, S, of the sensor. * A two-point pressure calibration can be performed to accurately determine the sensitivity and get rid of the offset calibration errors altogether. However, this can be very expensive in a high volume production due to extra time and labor involved. The system designer therefore designs a pressure sensor system by relying on the sensitivity and offset data given in the data sheet and using a linear equation to determine the pressure. Using the later, the sensed pressure is easily determined by: * SENSOR OUTPUT VOUT VFSO VP SENSOR OUTPUT VOFF VFSO P PRESSURE VOFF PREF(atm) P PMAX SPAN Figure 2. Effect of Offset Errors S VOFF PRESSURE PREF PMAX Figure 1. Definition of Span, Full-Scale Output, Offset and Sensitivity AUTO-ZERO CONSIDERATIONS IN APPLICATIONS There is an important consideration when implementing auto-zero. In order to use this technique, a zero pressure reference condition must be known to exist in the system. REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-375 AN1636 Freescale Semiconductor, Inc. There are a lot of applications that will lend themselves naturally to auto-zeroing. Typical applications are those that: IMPLEMENTATION OF AUTO-ZERO WITH A MICROCONTROLLER * experience a zero-pressure condition at system start up, Auto-zero can be implemented easily when the integrated sensor is interfaced to a microcontroller. The auto-zero algorithm is listed below: Freescale Semiconductor, Inc... * are idle for a long time (zero pressure), take a pressure measurement then go back to idle again. For example, in a water level measurement in a washing machine application, there is a zero pressure reference condition when the water in the tub is fully pumped out. Another application that is perfect for auto-zeroing is a beverage fill level measurement; a zero reference condition exists before the bottle is filled. HVAC air flow applications can also use auto-zeroing; before system start up, an auto-zero can be initiated. In other words, it can be used in applications where a zero pressure condition can exist in order to auto-zero the system. An auto-zero command can be automated by the system or can be commanded manually. Each system will have a different algorithm to command an auto-zero signal. For example, using the beverage fill level measurement as an example, the system will auto zero the sensor before the bottle is filled. 1. Sample the sensor output when a known zero reference is applied to the sensor (atmospheric pressure is a zero reference for gauge type measurement). Store current zero pressure offset as CZPO. 2. Sample the sensor output at the current applied pressure. Call this SP. 3. Subtract the stored offset correction, CZPO, from SP. The pressure being measured is simply calculated as: PMEAS = (SP *CZPO)/S. Note that the equation is simply a straight line equation, where S is the sensitivity of the sensor. The auto-zero algorithm is shown graphically in Figure 3. Start Sample Current Zero Offset, CZPO Sample Current Pressure, SP Calculate Pressure P MEAS + CP *SCZPO measure again auto-zero command received End Figure 3. Flow-Chart of the Auto-Zero Algorithm 3-376 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. IMPROVEMENT ON OFFSET ERROR In the following calculations, we will illustrate how auto-zero will improve the offset error contribution. We will use the MPXV4006G interfaced to an 8-bit A/D as an example. When auto-zero is performed, the offset errors are reduced and the resulting offset errors are replaced with the error (due to resolution) of the A/D. We can categorize the offset error contributions into temperature and calibration errors. Temperature Coefficient of Offset Error The offset error due to temperature is due to Temperature Coefficient of Offset, or TCO. This parameter is the rate of change of the offset when the sensor is subject to temperature. It is defined as: TCO = (VOFF/T). Freescale Semiconductor, Inc... The MPXV4006G has a temperature coefficient of offset (normalized with the span at 25C) of: TCO = (VOFF/T)/VFS@25C = 0.06% FS/C. As an example, if the sensor is subjected to temperature range between 10C and 60C, the error due to TCO is: TCO = (0.06% FS/C)*(60C * 10C) = "3.0% FS. Offset Calibration Errors Even though the offset is laser trimmed, offset can shift due to packaging stresses, aging and external mechanical stresses due to mounting and orientation. This results in offset calibration error. For example, the MPXV4006G data sheet shows this as: VOFF MIN = 0.100 V, VOFF TYPICAL = 0.225 V and VOFF MAX = 0.430 V. We can then calculate the offset calibration error with respect to the full scale span as: VOFF MIN,MAX = (VOFF TYPICAL VOFF MIN,MAX)/VFS. This results in the following offset calibration error, * VOFF MIN = 2.7% FS and VOFF MAX = 4.5% FS. Motorola Sensor Device Data AN1636 A/D Error As mentioned above, we can reduce offset errors (calibration and TCO) when we perform auto-zero. These errors are replaced with the A/D error (due to its resolution), OFFSETAUTOZERO = TCO + OFFSET = A/D. Typically, a sensor is interfaced to an 8-bit A/D. With the A/D reference tied to VRH = 5 V and VRL = 0 V, the A/D can resolve 19.6 mV/bit. For example, the MXPV4006G has a sensitivity of 7.5 mV/mmH20, the resolution is therefore, A/DRESOLUTION = 19.6 mV/bit)/(7.5 mV/mmH20) = 2.6 mmH20/bit. * Assuming +/ 1 LSB error, the error due to digitization and the resulting offset error is, A/D = OFFSETAUTOZERO = 2.6 mmH20/612 mmH20 = +/ 0.4% FS. * It can be seen that with increasing A/D resolution, offset errors can be further reduced. For example, with a 10-bit A/D, the resulting offset error contribution is only 0.1% FS when auto-zero is performed. If auto-zero is to be performed only once and offset correction data is stored in non-volatile memory, the TCO offset error and calibration error will not be corrected if the sensor later experiences a wide temperature range or later experience an offset shift. However, if auto-zero is performed at the operating temperature, TCO error will be compensated although subsequent offset calibration error will not be compensated. It is therefore best to auto-zero as often as possible in order to dynamically compensate the system for offset errors. CONCLUSION Auto-zero can be used to reduce offset errors in a sensor system. This technique can easily be implemented when an integrated pressure sensor is interfaced to an A/D and a microcontroller. With a few lines of code, the offset errors are effectively reduced; the resulting offset error reduction is limited only by the resolution of the A/D. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-377 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Noise Considerations for Integrated Pressure Sensors AN1646 Prepared by Ador Reodique, Sensor and Systems Applications Engineering and Warren Schultz, Field Engineering Freescale Semiconductor, Inc... INTRODUCTION Motorola Integrated Pressure Sensors (IPS) have trimmed outputs, built-in temperature compensation and an amplified single-ended output which make them compatible with Analog to Digital converters (A/D's) on low cost micro-controllers. Although 8-bit A/D's are most common, higher resolution A/D's are becoming increasingly available. With these higher resolution A/D's, the noise that is inherent to piezo-resistive bridges becomes a design consideration. The two dominant types of noise in a piezo-resistive integrated pressure sensor are shot (white) noise and 1/f (flicker noise). Shot noise is the result of non-uniform flow of carriers across a junction and is independent of temperature. The second, 1/f, results from crystal defects and also due to wafer processing. This noise is proportional to the inverse of frequency and is more dominant at lower frequencies3. Noise can also come from external circuits. In a sensor system, power supply, grounding and PCB layout is important and needs special consideration. The following discussion presents simple techniques for mitigating these noise signals, and achieving excellent results with high resolution A/D converters. EFFECTS OF NOISE IN SENSOR SYSTEM The transducer bridge produces a very small differential voltage in the millivolt range. The on-chip differential amplifier amplifies, level shifts and translates this voltage to a single- ended output of typically 0.2 volts to 4.7 volts. Although the transducer has a mechanical response of about 500 Hz, its noise output extends from 500 Hz to 1 MHz. This noise is amplified and shows up at the output as depicted in Figure 1. There is enough noise here to affect 1 count on an 8 bit A/D, and 4 or 5 counts on a 10 bit A/D. It is therefore important to consider filtering. Filtering options are discussed as follows. Figure 1. MPX5006 Raw Output REV 1 3-378 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1646 ware, a low-pass RC filter with a cutoff frequency of 650 Hz is recommended. A 750 ohm resistor and a 0.33 F capacitor have been determined to give the best results (see Figure 2) since the 750 ohm series impedance is low enough for most A/D converters. NOISE FILTERING TECHNIQUES AND CONSIDERATIONS For mitigating the effects of this sensor noise, two general approaches are effective, low pass filtering with hardware, and low pass filtering with software. When filtering with hard- +5 V 3 1 A/D 750 m m 1.0 F 0.01 F IPS Freescale Semiconductor, Inc... W m 0.33 F 2 Figure 2. Integrated Pressure Sensor with RC LP Filter to Filter Out Noise nical data sheet if input impedance is a concern. In applications where the A/D converter is sensitive to high source impedance, a buffer should be used. The integrated pressure sensor has a rail-to-rail output swing, which dictates that a rail-to-rail operational amplifier (op amp) should be used to avoid saturating the buffer. A MC33502 rail-to-rail input and output op amp works well for this purpose (see Figure 3). This filter has been tested with an MC68HC705P9 microcontroller which has a successive approximation A/D converter. Successive approximation A/D's are generally compatible with the DC source impedance of the filter in Figure 2. Results are shown in Figure 4. Some A/D's will not work well with the source impedance of a single pole RC filter. Please consult your A/D converter tech- +5 V - 3 A/D 1 + 750 m 1.0 F m W MC33502 0.01 F IPS 2 m 0.33 F Figure 3. Use a Rail-to-Rail Buffer to Reduce Output Impedance of RC Filter Averaging is also effective for filtering sensor noise. Averaging is a form of low pass filtering in software. A rolling average of 8 to 64 samples will clean up most of the noise. A 10 sample average reduces the noise to about 2.5 mV peak to peak and a 64 sample average reduces the noise to about 1 mV peak to peak (see Figures 5 and 6). This method is simple and requires no external components. However, it does require RAM for data storage, extra computation cycles and code. In applications where the microcontroller is resource limited or pressure is changing relatively rapidly, averaging alone may not be the best solution. In these situations, a combination of RC filtering and a Motorola Sensor Device Data limited number of samples gives the best results. For example, a rolling average of 4 samples combined with the RC filter in Figure 2 results in a noise output on the order of 1 mV peak to peak. Another important consideration is that the incremental effectiveness of averaging tends to fall off as the number of samples is increased. In other words, the signal-to-noise (S/N) ratio goes up more slowly than the number of samples. To be more precise, the S/N ratio improves as the square root of the number of samples is increased. For example, increasing the number of samples from 10, in Figure 5, to 64, in Figure 6, reduced noise by a factor of 2.5. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-379 Freescale Semiconductor, Inc... AN1646 Freescale Semiconductor, Inc. Figure 4. Output After Low Pass Filtering Figure 5. Output with 10 Averaged Samples 3-380 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1646 Figure 6. Output with 64 Averaged Samples Figure 7. Filtered Sensor Output and Averaged Over 10 Samples Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-381 Freescale Semiconductor, Inc. AN1646 Freescale Semiconductor, Inc... POWER SUPPLY Since the sensor output is ratiometric with the supply voltage, any variation in supply voltage will also proportionally appear at the output of the sensor. The integrated pressure sensor is designed, characterized and trimmed to be powered with a 5 V +/- 5% power supply which can supply the maximum 10 mA current requirement of the sensor. Powering the integrated sensor at another voltage than specified is not recommended because the offset, temperature coefficient of offset (TCO) and temperature coefficient of span (TCS) trim will be invalidated and will affect the sensor accuracy. From a noise point of view, adequate de-coupling is important. A 0.33 F to 1.0 F ceramic capacitor in parallel with a 0.01 F ceramic capacitor works well for this purpose. Also, with respect to noise, it is preferable to use a linear regulator such as an MC78L05 rather than a relatively more noisy switching power supply 5 volt output. An additional consideration is that the power to the sensor and the A/D voltage reference should be tied to the same supply. Doing this takes advantage of the sensor output ratiometricity. Since the A/D resolution is also ratiometric to its reference voltage, variations in supply voltage will be canceled by the system. LAYOUT OPTIMIZATION In mixed analog and digital systems, layout is a critical part of the total design. Often, getting a system to work properly depends as much on layout as on the circuit design. The following discussion covers some general layout principles, digital section layout and analog section layout. General Principles: There are several general layout principles that are important in mixed systems. They can be described as five rules: Rule 1: Minimize Loop Areas. This is a general principle that applies to both analog and digital circuits. Loops are antennas. At noise sensitive inputs, the area enclosed by an incoming signal path and its return is proportional to the amount of noise picked up by the input. At digital output ports, the amount of noise that is radiated is also proportional to loop area. Rule 2: Cancel fields by running equal currents that flow in opposite directions as close as possible to each other. If two equal currents flow in opposite directions, the resulting electromagnetic fields will cancel as the two currents are brought infinitely close together. In printed circuit board layout, this situation can be approximated by running signals and their returns along the same path but on different layers. Field cancellation is not perfect due to the finite physical separation, but is sufficient to warrant serious attention in critical paths. Looked at from a different perspective, this is another way of looking at Rule # 1, i.e., minimize loop areas. SENSOR Rule 3: On traces that carry high speed signals avoid 90 degree angles, including "T" connections. If you think of high speed signals in terms of wavefronts moving down a trace, the reason for avoiding 90 degree angles is simple. To a high speed wavefront, a 90 degree angle is a discontinuity that produces unwanted reflections. From a practical point of view, 90 degree turns on a single trace are easy to avoid by using two 45 degree angles or a curve. Where two traces come together to form a "T" connection, adding some material to cut across the right angles accomplishes the same thing. Rule 4: Connect signal circuit grounds to power grounds at only one point. The reason for this constraint is that transient voltage drops along the power grounds can be substantial, due to high values of di/dt flowing through finite inductance. If signal processing circuit returns are connected to power ground at multiple points, then these transients will show up as return voltage differences at different points in the signal processing circuitry. Since signal processing circuitry seldom has the noise immunity to handle power ground transients, it is generally necessary to tie signal ground to power ground at only one point. Rule 5: Use ground planes selectively. Although ground planes are highly beneficial when used with digital circuitry, in the analog world they are better used selectively. A single ground plane on an analog board puts parasitic capacitance in places where it is not desired, such as at the inverting inputs of op amps. Ground planes also limit efforts to take advantage of field cancellation, since the return is distributed. ANALOG LAYOUT In analog systems, both minimizing loop areas and field cancellation are useful design techniques. Field cancellation is applicable to power and ground traces, where currents are equal and opposite. Running these two traces directly over each other provides field cancellation for unwanted noise, and minimum loop area. Figure 8 illustrates the difference between a power supply de-coupling loop that has been routed correctly and one that has not. In this figure, the circles represent pads, the schematic symbols show the components that are connected to the pads, and the routing layers are shown as dark lines (top trace) or grey lines (bottom trace). Note that by routing the two traces one over the other that the critical loop area is minimized. In addition, it is important to keep de-coupling capacitors close to active devices such as MPX5000-series sensors and operational amplifiers. As a rule of thumb, when 50 mil ground and Vcc traces are used, it is not advisable to have more than 1 inch between a de-coupling capacitor and the active device that it is intended to be de-coupled. SENSOR TOP TRACE BOT TRACE +5 V GND +5 V GND RECOMMENDED AVOID Figure 8. Minimizing Loop Areas 3-382 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. For similar reasons it is desirable to run sensor output signals and their return traces as close to each other as possible. Minimizing this loop area will minimize the amount of external noise that is picked up by making electrical connections to the sensor. AN1646 nity. Single traces are easy, two forty five degree angles or a curve easily accomplish a 90 degree turn. It is just as important to avoid 90 degree angles in T connections. Figure 10 illustrates correct versus incorrect routing for both cases. SINGLE TRACE Freescale Semiconductor, Inc... DIGITAL LAYOUT The primary layout issue with digital circuits is ground partitioning. A good place to start is with the architecture that is shown in Figure 9. This architecture has several key attributes. Analog ground and digital ground are both separate and distinct from each other, and come together at only one point. For analog ground it is preferable to make the one point as close as possible to the analog to digital converter's ground reference (VREFL). The power source ground connection should be as close as possible to the microcontroller's power supply return (VSS). Note also that the path from VREFL to VSS is isolated from the rest of digital ground until it approaches VSS. AVOID GOOD PRACTICE T-CONNECTION DIGITAL GROUND/GROUND PLANE AVOID GOOD PRACTICE Figure 10. 90 Degree Angles CONCLUSION VREFL SENSOR/ANALOG GROUND VSS POWER GROUND Piezo-resistive pressure sensors produce small amounts of noise that can easily be filtered out with several methods. These methods are low pass filtering with an RC filter, averaging or a combination of both which can be implemented with minimal hardware cost. In a mixed sensor system, noise can be further reduced by following recommended power supply, grounding and layout techniques. REFERENCES Figure 9. Ground Partitioning In addition to grounding, the digital portion of a system benefits from attention to avoiding 90 degree angles, since there are generally a lot of high speed signals on the digital portion of the board. Routing with 45 degree angles or curves minimizes unwanted reflections, which increases noise immu- Motorola Sensor Device Data [1] AN1626 Noise Management in Motor Drives, Warren Schultz, Motorola, Inc. [2] Noise Reduction Techniques In Electronic Systems 2nd Edition, Henry W. Ott, John Wiley & Sons. [3] Noise: Comparing Integrated Pressure Sensors and Op Amps, Ira Basket, Motorola Sensor Products Division internal paper. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-383 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Compound Coefficient Pressure Sensor PSPICE Models AN1660 Freescale Semiconductor, Inc... Prepared by: Warren Schultz PSPICE models for Uncompensated, MPX2000 series, and MPX5000 series pressure sensors are presented here. These models use compound coefficients to improve modeling of temperature dependent behavior. The discussion begins with an overview of how the models are structured, and is followed by an explanation of compound coefficients. The emphasis is on how to use these models to estimate sensor performance. They can be found electronically on a disk included in ASB200 Motorola Sensor Development Controller kits, and on the WEB at: In the MPX2000 and MPX5000 models, temperature coefficient of span (TCSP) is handled differently than the other parameters. The non-linear behavior of span over temperature is calculated from the interaction of the transducer's temperature coefficient of span (TCSP), the transducer's temperature coefficient of resistance (TCRB), and the effects of inserting fixed resistance, RTCSPAN, in series with the bridge. The result is a temperature coefficient of span that closely resembles the real thing, but is not directly controlled by the user. http://www.mot-sps.com/home2/models/bin/sensor2.html LINEAR TO COMPOUND CONVERSION The compound coefficients used in these models are from equations of the form: (1) R(Temp) = R25(1 TCR)(Temp - 25) MODEL STRUCTURE Models for all three sensors series share a common structure. They are complete models set up to run as is. To obtain output voltage versus pressure, it is only necessary to run the model and display V(2,4) or V(1,0). V(2,4) gives the output voltage for Uncompensated and MPX2000 series sensors. V(1,0) applies to MPX5000 sensors. In both cases, V(2,4) and V(1,0) correspond to the pin numbers where output voltage would be, if probed on an actual part. These models are divided into five sections to facilitate ease of use. They are: * INPUT PARAMETERS * LINEAR TO COMPOUND CONVERSION * MODEL COEFFICIENTS * TRANSDUCER * STIMULUS Each of these sections is described in the following discussion. INPUT PARAMETERS This section contains input parameters that describe measurable sensor characteristics. Inputs such as full scale pressure (FSP), full scale span (FSS) offset voltage (VOFFSET), and temperature coefficient of offset voltage (TCOS) are made here. Characteristics that are specific to the transducer, such as bridge impedance (RBRIDGE), temperature coefficient of bridge resistance (TCRB), and temperature coefficient of span (TCSP) are also listed here. Parameters such as VOFFSET that set an output value for the sensor are used to calculate resistance values that produce those outputs. For example, if you input 100 mV of offset voltage and a 10 V/degree temperature coefficient of offset voltage, the model will calculate the bridge resistance values necessary to produce 100 mV of offset voltage and a 10 V/degree temperature coefficient. ) where R25 is resistance at 25 degrees Celsius , TCR is temperature coefficient of resistance, Temp is an abbreviation for Temperature in degrees Celsius, and R(Temp) is the function resistance versus temperature. The TCR (temperature coefficient of resistance) in equation (1) is a different number than a temperature coefficient that is stated in linear terms. The three statements in this section convert linear coefficients to the compound values that the models need. This conversion is based upon a 100 degree difference between the two points at which the linear coefficients have been measured. MODEL COEFFICIENTS In this section most of the calculation is performed. Values for the transducer bridge resistors are determined from pressure, temperature, offset, temperature coefficient of offset, span, temperature coefficient of span, and temperature coefficient of resistance inputs. A series of parameter statements are used, as much as is practical, to do calculations that will fit in an 80 character line without wraparounds. These calculations use PSPICE's .PARAMETER function, making the models specific to PSPICE. Parameters are described as follows: KP -- Pressure constant; translates pressure into a bridge resistance multiplier KO -- Offset constant; offset component of bridge resistance DT -- Delta temperature; Temperature Celsius *25 degrees KTCO -- Temperature coefficient of offset constant; translates temperature coefficient of offset into bridge resistance REV 1 3-384 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. TCR -- Temperature coefficient of bridge resistance; shaped by a Table that accounts for cold temperature non-linearity's ROFF -- Offset resistance; determines value of RS13 (MPX5000 series) After these calculations are made, the final bridge resistance calculation is performed in the circuit section. The value for bridge resistors RS1 and RS3 is RPH + ROH. Bridge resistors RS2 and RS4 are equal to RPL-ROL. TCR2 -- Temperature coefficient of contact resistance; shaped by a Table that accounts for cold temperature non-linearity's TCS -- Temperature coefficient of Span; shaped by a Table that accounts for cold temperature non-linearity's CIRCUIT Three circuits are used to model the three sensor families, one each for the Uncompensated series, MPX2000 series, and MPX5000 series sensors. Schematics that are derived from the circuit netlists are shown in Figures 1, 2, and 3. They are discussed beginning with the Uncompensated series, which is the least complex. RPH -- Bridge Resistance (RS1 and RS3) modified by pressure and temperature ROH -- Offset Component of Bridge Resistors RS1 and RS3 RPL -- Bridge Resistance (RS2 and RS4) modified by pressure and temperature Uncompensated Series: The Uncompensated Series sensors (MPX10, MPX50, and MPX100) are modeled as Wheatstone bridges. In the configuration that is shown in Figure 1, resistors RS2 and RS4 decrease in value as pressure is applied. Similarly, RS1 and RS3 increase in value as pressure is applied. Resistors RS5 and RS7 are contact resistors. They represent real physical resistors that are used to make contact to the bridge. Resistors RS6 and RS8 are included to satisfy PSPICE's requirement for no floating nodes. That's it. The netlist in this model is quite simple. The hard part is calculating the values for RS1, RS2, RS3, and RS4. ROL -- Offset Component of Bridge Resistors RS2 and RS4 Freescale Semiconductor, Inc... AN1660 KB -- Bias Constant; adjusts KP for bias voltage effects of span compensation network (MPX2000 and MPX5000 series sensors) KBT -- Bias Constant; adjusts KO for bias voltage effects of span compensation network (MPX2000 and MPX5000 series sensors) GAIN -- Instrumentation amplifier gain; differential gain (MPX5000 series) 3 NOTES: * TEMPERATURE SENSITIVE * * TEMPERATURE & PRESSURE SENSITIVE RS1** 475 RS5 * 4 RS2 ** 475 RS7 * 1 5 2 675 750 RS4 ** 475 RS3 ** 475 RS8 1000MEG RS6 1000MEG 0 Figure 1. MPX10 and 100 PSPICE Compound Coefficient Model Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-385 Freescale Semiconductor, Inc. AN1660 Resistor RS12 is also added to the Uncompensated model. It represents additional impedance that is associated with the MPX2000 series sensors' offset trim network. Offset performance is modeled behaviorally. Inputs for offset (VOFFSET) and temperature coefficient of offset (TCOS) are translated into bridge resistance values that produce the specified performance. This behavioral approach was chosen in order to make it easy to plug in different values for VOFFSET and TCOS. MPX2000 Series: The MPX2000 Series sensors (MPX2010, MPX2050, MPX2100, and MPX2200) add span compensation and trim resistors to the Uncompensated model. These resistors are shown in Figure 2 as RS9, RS11, and RS10. The temperature coefficient of resistance (TCR) for the bridge resistors works against fixed resistors RS9 and RS11 to produce a bias to the bridge that increases with temperature. This increasing bias compensates for the temperature coefficient of span, which is negative. 6 RS9 NOTES: * TEMPERATURE SENSITIVE * * TEMPERATURE & PRESSURE SENSITIVE Freescale Semiconductor, Inc... 3 RS1** RS2** RS5* 4 RS10 5 RS4 ** RS7* 8 RS12 1 2 RS3 ** RS6 RS8 7 RS11 0 Figure 2. MPX2000 Series PSPICE Compound Coefficient Model MPX5000 Series: The MPX5000 Series sensors (MPX5010, MPX5050, MPX5100, MPX5700, and MPX5999) add an instrumentation amplifier to the MPX2000 series model. This amplifier is shown in Figure 3. It consists of operational amplifiers ES1, ES2, ES3, and ES4. Amplifiers ES1, ES2 and ES3 are mod- 3-386 eled as voltage controlled voltage sources with gains of 100,000. Offset voltage, input bias current effects, etc. are taken into account with the values that are used to determine offset voltage and temperature coefficient of the sensor bridge. Amplifier ES4 models saturation voltage. Its output follows the output of ES3 with saturation limits at 75 millivolts and 4.9 volts. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 6 AN1660 NOTES: RS9 1350 * TEMPERATURE SENSITIVE * * TEMPERATURE & PRESSURE SENSITIVE 3 350** RS1 RS5 * 4 5 RS2 ** 350 RS7* RS10 14 750 7 2 1K 675 RS4 ** 350 RS11 RS3 ** 350 RS8 1000MEG RS6 1000MEG 0 RS12 10K Freescale Semiconductor, Inc... 9 RS13 265.5 ES1 RS14 8 + - 11 ES2 ES3 + - + - G=100,000 RS15 112K G=100,000 500 RS16 10 13 500 G=100,000 RS17 112K ES4 12 + - 1 V(1,0) Figure 3. MPX5000 Series PSPICE Compound Coefficient Model STIMULUS The last section of these models is labeled STIMULUS. Bias voltage, pressure, and temperature are applied here. Nominal bias voltage (VCC) is 3.0 volts for Uncompensated sensors, 10.0 volts for MPX2000 sensors, and 5.0 volts for MPX5000 sensors. Pressure is selected on the second line. It is effective when the * on line 4 is removed to command a temperature sweep. Line 3 calls for a sweep of pressure and temperature. An * placed in front of Line 3 allows the temperature sweep on line 4 to be selected. COMPOUND COEFFICIENTS Applying temperature coefficients to variables such as resistance is an essential part of modeling. The linear approach, that is usually used, is based upon the assumption that changes are small, and can be modeled with a linear approximation. Using temperature coefficient of resistance as (TCR) as an example, the linear expression takes the form: (2) R(Temp) = R25(1 ) TCR(Temp - 25)) Provided that the TCR in equation (2) is 100 parts per million per degree Celsius or less this approach works quite well. With sensor TCR's of several thousand parts per million per degree Celsius, however, the small change assumption does not hold. To accurately model changes of this magnitude, the mathematical expression has to describe a physical process where a unit change in temperature produces a constant per- Motorola Sensor Device Data centage change in resistance. For example, a 1% per degree TCR applied to a 1 K Ohm resistor should add 10 ohms to the resistor's value going from 25 to 26 degrees. At 70 degrees, where the resistor has increased to 2006 Ohms, going from 70 to 71 degrees should add 20.06 Ohms to its value. The error in the linear expression comes from that fact that it adds 10 ohms to the resistor's value at all temperatures. A physical process whereby a unit change in temperature produces a constant percentage change in resistance is easily modeled by borrowing an expression from finance. Compound interest is a direct analog of temperature coefficients. With compound interest, a unit change in time produces a constant percentage change in the value of a financial instrument. It can be described by the expression: (3) Future Value = Present Value (1 i)n ) where i is the interest rate and n is the number of periods. Substituting R25 for Present Value, R(Temp) for Future Value, TCR for i, and (Temp - 25) for n yields: (4) R(Temp) = R25(1 ) TCR)(Temp *25) Equation (4) works quite well, provided that TCR is constant over temperature. When modeling semiconductor resistors, it is also necessary to account for variable TCR's. At cold, the TCR for p type resistors changes with temperature. These changes are modeled using TABLE functions that have 3 values for TCR. Results of this modeling technique versus actual measurements and a linear model are summarized in Table 1. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-387 Freescale Semiconductor, Inc. AN1660 Table 1. Actual versus Modeled R(Temp) Temp Measured Compound Linear *40 *25 R(Temp) Model Model 406 406 372 418 418 395 In Table 1, 25 and 150 degree Celsius data points were used to determine both linear and compound temperature coefficients. Therefore, measured values, linear model values and compound model values all match at these two temperatures. At other temperatures, the linear model exhibits errors that are significant when modeling piezoresistive pressure sensors. The compound model, however, tracks with measured values to within 1 Ohm out of 500 Ohms. EXAMPLES 445 445 434 474 474 474 50 509 508 513 75 545 545 552 100 585 584 592 125 627 626 632 150 671 671 671 Freescale Semiconductor, Inc... 0 25 Two examples of what the model outputs look like are shown in Figures 4 and 5. Figure 4 shows a sweep of pressure versus output voltage (VOUT) at 0, 25, and 85 degrees Celsius, for an MPX2010 sensor. It has the expected 0 to 25 mV output voltage, given a 0 to 10 kPa pressure input. At these three temperatures, compensation is sufficiently good that all three plots look like the same straight line. Figure 4. MPX2010 VOUT versus Pressure and Temperature To produce the plot in Figure 4, the stimulus section is set up as follows, and V(2,4) is probed. ***************************STIMULUS**************************** VCC 6 0 DC=10; DC BIAS FROM PIN 3 TO PIN 1 .PARAM PRESSURE=0; INPUT PRESSURE (kPa) .DC PARAM PRESSURE 0_Kpa 10_Kpa .5_Kpa TEMP LIST 0 25 85 *.DC PARAM TEMP -40 125 5 * This is the default configuration with which the model is shipped. To change to a sweep of zero pressure voltage versus temperature, an asterisk is placed on line 3 and removed from line 4. The stimulus section then looks as follows: 3-388 ****************************STIMULUS*************************** VCC 6 0 DC=10; DC BIAS FROM PIN 3 TO PIN 1 .PARAM PRESSURE=0; INPUT PRESSURE (kPa) *.DC PARAM PRESSURE 0_Kpa 10_Kpa .5_Kpa TEMP LIST 0 25 85 .DC PARAM TEMP -40 125 5 * Again, V(2,4) is probed. The resulting output appears in Figure 5. This plot shows offset versus temperature performance that is typical of MPX2000 series sensors. From 40 to 85 degrees Celsius, offset compensation is quite good. Above 85 degrees there is a hook in this curve, that is an important attribute of the sensor's performance. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com * ) Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1660 Figure 5. MPX2010 Offset versus Temperature CONCLUSION PSPICE models for Uncompensated, MPX2000 series, and MPX5000 series pressure sensors are available for estimating sensor performance. These models make use of the compounding concept that is used in finance to calculate compound interest. The resulting compound temperature coefficients do a better job than linear methods of modeling temperature dependent behavior. These models make extensive use of PSPICE's .PARAMETER statement, and are, therefore, specific to PSPICE. They are intended as references for determining typical sensor performance, and are structured for easy entry of alternate assumptions. DISCLAIMERS Macromodels, simulation models, or other models provided by Motorola, directly or indirectly, are not warranted by Motorola as fully representing all of the specifications and operating characteristics of the semiconductor product to which the model relates. Moreover, these models are furnished on an "as is" basis without support or warranty of any kind, either expressed or implied, regarding the use thereof and Motorola specifically disclaims all implied warranties of merchantability and fitness of the models for any purpose. Motorola does not assume any liability arising out of the application or use of the models including infringement of patents and copyrights nor does Motorola convey any license under its patents and copyrights or the rights of others. Motorola reserves the right to make changes without notice to any model. Although macromodels can be a useful tool in evaluating device performance in various applications, they cannot Motorola Sensor Device Data model exact device performance under all conditions, nor are they intended to replace breadboarding for final verification. Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters can and do vary in different applications. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and (Motorola logo symbol) are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/ Affirmative Action Employer. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-389 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Washing Appliance Sensor Selection AN1668 Prepared by Ador Reodique Sensor and Systems Applications Engineer Freescale Semiconductor, Inc... INTRODUCTION North American washing machines currently in production use mechanical sensors for water level measurement function. These sensors are either purely mechanical pressure switch with discrete trip points or electromechanical pressure sensor with an on-board electronics for a frequency output. High efficiency machines require high performance sensors (accuracy, linearity, repeatability) even at lower pressure ranges. Benchmarks indicate that these performance goals is difficult to achieve using current mechanical pressure sensors1. In Europe, where energy conservation is mandated, washing machine manufacturers have started to look at electronic solutions where accuracy, reliability, repeatability and additional functionality is to be implemented. North American and Asia Pacific manufacturers are also looking for better solutions. From surveys of customer requirements, a typical vertical- axis machine calls for a sensor with 600 mmH2O (24 " H2O ~ 6 kPa) sensor with a 5 % FS accuracy spec. Certain appliances call for a lower pressure range especially in Europe where horizontal axis machines are common. SENSOR SOLUTIONS For the typical 600 mmH2O, 5 % FS spec, an off the shelf solution available today is the MPX10/MPX12, MXP2010 and the MPXV4006G sensor. The MPX10 (or the MPX12) is 10 kPa (40 " H2O) full-scale pressure range device. It is uncompensated for temperature and untrimmed offset and full-scale span. This means that the end user must temperature compensate as well as calibrate the full-scale offset and span of the device. The output of the device must be amplified using a differential amplifier (see Figure 1) so it can be interfaced to an A/D and to obtain the desired range. Since the MPX10/MPX12 sensors must be calibrated, the implications of this device being used in high-volume production is expensive. Because the offset and full-scale output can vary from part to part, a two-point calibration is required as a minimum. A two point calibration is a time consuming procedure as well as possible modification to the production line to accommodate the calibration process. The 3-390 circuitry must also accommodate for trimming, i.e., via trimpots and/or EEPROM to store the calibration data. This adds extra cost to the system. The MPX2010 is a 10kPa (40" H2O), temperature compensated, offset and full-scale output calibrated device. A differential amplifier like the one shown in Figure 1 should be used to amplify its output. Unlike the MPX10 or MPX12, this device does not need a two-point calibration but auto-zeroing can improve its performance. This procedure is easily implemented using the system MCU. The MPXV4006G is a fully integrated pressure sensor specifically designed for appliance water level sensing application. This device has an on board amplification, temperature compensation and trimmed span. An auto-zero procedure should be implemented with this device (see Application Note AN1636). Because expensive and time consuming calibration, temperature compensation and amplification is already implemented, this device is more suitable for high volume production. The MPXV4006G integrated sensor is guaranteed to be have an accuracy of +/-3 % FS over its pressure and temperature range. For washing machine applications where low cost and high volume productions are involved, both the MPX2010 and MPXV4006G are recommended. Both solutions can be used in current vertical axis machines where the water level in the 600 mmH2O or 24 " H2O range. In the following, a comparison is made between MPX2010 and MPXV4006G in terms of system and performance considerations to help the customer make a decision. EXPECTED ACCURACY OF THE MPX2010 SYSTEM SOLUTION The MPX2010 compensated sensor has an off the shelf overall RMS accuracy of +/-7.2 % FS over 0 to 85C temperature range. Auto-zeroing can improve the sensor accuracy to +/- 4.42 % FS. However, since this sensor does not have an integrated amplification, its amplifier section must be designed carefully in order to meet the target accuracy requirement. The MPX2010 compensated sensor has the following specifications shown on Table 1. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1668 Table 1. MPX2010 Specifications Characteristic Min Pressure Range Typ 0 Supply Voltage 10 Supply Current Unit 10 kPa 16 Vdc 6 Full Scale Span 24 Sensitivity Pressure Hysterisis 26 mV 1 mV 25 *1 Linearity mA 25 *1 Offset mV/kPa 1 %VFSS %VFSS 0.1 * Temperature Hysterisis ( 40 to 125C) 0.5 *1 *1 Temperature Effect on Span Temperature Effect Offset (0 to 85C) Freescale Semiconductor, Inc... Max %VFSS %VFSS 1 Input Impedance 1300 Output Impedance 1400 1 mV 2550 ohms 3000 ohms Response Time (10% to 90%) 1 ms Warm-Up 20 ms The sensor system errors is made up of the sensor errors, amplifier errors and A/D errors. In other words, With auto-zeroing, the offset calibration, temperature effect on offset and offset stability is reduced or eliminated, eSystem eSensor + eSensor ) eAmplifier ) eADResolution 2 2 2 (1) Table 2 shows the MPX2010 with the errors converted to %VFSS. The expected maximum root mean squared error of the sensor is (2) eSensor + SpanCal2 ) Lin2 ) Phys2 ) Thys2 ) Tcs2 ) OffCal2 ) Tco2 ) OffStab2 = +/- 7.19 % FS. + SpanCal ) Lin ) Phys ) Thys ) Tcs 2 2 2 2 (3) 2 = +/- 4.42 % FS. The sensor error is calculated using the full-scale pressure range of the device, 0 to 85C temperature and 10 V excitation. In comparison with the MPXV4006G solution, the expected accuracy of the system (MPXV4006G + 8 bit A/D) with auto-zero is 3.1 % FS. Table 2. MPX2010 span, offset and calculated maximum RMS error. *This assumes that the power supply is constant. Span Errors (converted to %VFSS) Symbol Error Value SpanCal 4 Lin 1 Pressure Hysterisis Phys 0.1 Temperature Hysterisis Thys 0.5 %VFSS %VFSS Tcs 1.5 %VFSS OffCal 4 Tco 4 %VFSS %VFSS OffStab 0.5 %VFSS Span Calibration Linearity Temperature Effect on Span Note Unit %VFSS %VFSS Offset Errors (converted to %VFSS) Offset Calibration Temperature Effect on Offset Offset Stability Calculated Maximum RMS Errors RMS Error No Compensation* 7.19 With auto-zero 4.42 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com %FS %FS 3-391 Freescale Semiconductor, Inc. AN1668 AMPLIFIER SELECTION AND AMPLIFIER INDUCED ERRORS A differential amplifier is needed to convert the differential output of the MPX2010 sensor to a high level ground- referenced (single-ended). The classic three-op amp instrumentation amplifier can be used. However, it requires additional components (3 op-amps and possibly a split power supply). An instrumentation topology shown in Figure 1 requires only a single supply and only 2 op-amps and 1% resistors. +VCC R2 R4 R+S1 R1 2 VREF - + 3 Freescale Semiconductor, Inc... R+S2 1 6 R3 U1A - 5 + U1B 7 VOUT_FS +VCC 4 3 * S PRESSURE SENSOR X1 1 S+ 2 Figure 1. MPX2010 Amplifier Circuit The circuit uses a voltage divider R+S1 and R+S2 to provide the reference (level shift), U1A and U1B are non-inverting amplifiers arranged in a differential configuration with gain resistors R1, R2, R3 and R4. Note that U1B is the main gain stage and it has the most gain. It is recommended to place a 0.015 F capacitor in it's feedback loop (in parallel with R4) to reduce noise. The amplifier output can be characterized with the equation below: Gain + R4 )1 R3 Voffset + VREF R2*R1 * VSCM R1*R3 * R2*R4 R1*R3 + (S)* S*) Gain ) Voffset where (S)* S*) + Sensor differential output ) Sensor offset Vout 1 (4) (5) (6) (7) Equation 4 is the differential gain of the amplifier and equation 5 is the resulting offset voltage of the amplifier. The above equations assume that the amplifier is close to ideal (high AOL , low input offset voltage and low input offset bias currents). Since an ideal op-amp is hard to come by, the customer should select an op-amp based on cost and perfor- 3-392 mance. Below are some points to keep in mind when selecting an op-amp and designing the amplifier circuit. Note that the ratio R2*R4/R1*R3 controls the system offset as well as the common mode error of the amplifier. Mismatches in these resistors will result in an offset and common mode error which appear as offset. It is therefore recommended to use 1% metal film resistors to reduce these errors. Also, Vref source impedance should be minimized in comparison with R1 in order to reduce common mode error. Amplifier input offset and input bias currents can induce errors. For example, an input offset (Vio) of the amplifier can become significant when the closed-loop gain of the amplifier is increased. Furthermore, there is also a temperature coefficient of the input voltage offset which contribute an additional error across temperature. If the input bias current of the amplifier is not taken into account in the design, it can also become a source of error. A technique to reduce this error is to match the impedance the source impedance of what the op-amp input pins sees. It is important to note that high performance op-amps are more expensive. An MC33272 op-amp has a low input offset and low input bias current which is suitable for the two-op amp amplifier design. We can see that there is a tradeoff between accuracy and cost when designing a solution with the MPX2010. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. When designing a system based on the MPX2010, it is important to take into account errors due to parametric variation of the sensor (i.e. offset calibration, span calibration, TcS, TcO), power supply and the inherent errors of the amplification circuit. The offset and span errors greatly determines the resolution of the system (which adds to the system error). Even though the system offset error can be nulled out by auto-zeroing, these errors must be accounted for when setting the system gain (see AN1556 for more details). This forces the total span of the system to be smaller, because we must reserve an extra headroom from the total span to account for amplifier and A/D variations (i.e. amp. sat. voltage, power supply varia- AN1668 tion, A/D quantization error, and gain errors ). If these errors are not accounted for, it could, for example, result in non- linearity errors if the sensor span or offset error causes the amplified output of the sensor to reach the saturation voltage of the amplifier. As an example, a MPX2010 sensor system is designed which has a range of 600 mmH2O FS range with a +/- 5 % FS RMS error. The system uses a +5 V +/- 5% linear regulated power supply, a MC33272 dual op-amp and a 1% resistors. Table 3 shows the resulting specification and component values for the system based on MPX2010 sensor. Table 3. MPX2010 Sensor System Values MPX2010 Sensor Design Freescale Semiconductor, Inc... Parameter Description Vcc Value Units Reg Power Supply 5 V Gain 433 V/V Vout_FS Full Scale Span 3.02 V Vref Offset Reference 0.66 V Differential Gain Parts List U1A,U1B MC33272 Op-amp R1 Gain Resistor 39.2K Ohms R2 Gain Resistor 90.9 Ohms R3 Gain Resistor 909 Ohms R4 Gain Resistor 392K Ohms R + S1 Level Shift Resistor 1K Ohms R + S2 Level Shift Resistor 150 Ohms X1 MPX2010 Table 4. Performance Comparison between MPX2010 and MPXV4006G Solution MPX2010 Solution Error (FS = 600 mmH2O) Error Contribution MPXV4006G Solution Error (FS = 612 mmH2O) +/- % FS +/- mmH2O +/- % FS +/- mmH2O Max Sensor Error 7.19 43 3.00 18 System Resolution (A/D + Amplification) 1.30 8 0.80 5 System Error (Sensor + A/D + Amplification) 7.3 44 3.10 19 System Error with Auto-Zero 4.6 28 Note that the error due to system resolution is higher for the MPX2010 solution (+/- 2 bit A/D accuracy). This is because the MPX2010 span is limited as discussed above. Also, this accuracy assumes that the amplifier does not induce signifi- Motorola Sensor Device Data t3 t19 cant errors. As noted MPXV4006G sensor has better overall accuracy. The system resolution is very good because of its large span (4.6 V versus 3.0 V typical). www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-393 Freescale Semiconductor, Inc. AN1668 SUMMARY REFERENCES [1] Benchmark of Washing Machine Mechanical Sensor, Jack Rondoni, Motorola Internal Document. [2] Mechanical Sensor Characterization, Ador Reodique, Motorola Internal Document. [3] AN1551 Low Pressure Sensing with the MPX2010 Pressure Sensor, Jeff Baum, Motorola Application Note. [4] AN1636 Implementing Auto-Zero for Integrated Pressure Sensors, Ador Reodique, Motorola Application Note. [5] AN1556 Designing Sensor Performance Specifications for MCU-based Systems, Eric Jacobsen and Jeff Baum, Motorola Application Note. Freescale Semiconductor, Inc... Several washing machine solutions were examined. The MPX10/12 solution can be expensive in terms of additional support circuitry and the added time and labor involved during the calibration procedure. The MPX2010 is good alternative for high volume manufacturing because is already calibrated. With this solution, however, the system amplifier design must be chosen and designed carefully in order to minimize the system error. This is a consideration when deciding to implement a high accuracy solution with the MPX2010 because the cost of the system will go up. The MPXV4006G solution is geared towards high volume manufacturing because trimming, compensation and amplification is already on board. Besides the system simplicity and using less component, the resolution and overall accuracy of this solution is better than the MPX2010 solution. In some cases, less components can actually improve the reliability and manufacturability the system. 3-394 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1950 Water Level Monitoring Freescale Semiconductor, Inc... By Michelle Clifford Applications Engineer Sensor Products Division Tempe, AZ INTRODUCTION Many washing machines that are currently in production use a mechanical sensor for water level detection. Mechanical sensors work with discrete trip points that enable water level detection only at those points. The purpose for this reference design is to allow the user to evaluate a pressure sensor for not only water level sensing to replace a mechanical switch, but also for water flow measurement, leak detection, and other solutions for smart appliances. This system continuously monitors water level and water flow using the temperature compensated MPXM2010GS pressure sensor in the low cost MPAK package, a dual op-amp, and the MC68HC908QT4, 8-pin microcontroller. The height of most washing machine tubs is 40cm, therefore the water height range that this system will be measuring is between 0-40cm. This corresponds to a pressure range of 0 - 4 kPa. Therefore, the MPXM2010GS was selected for this system. The sensor sensitivity is 2.5mV/kPa, with a full-scale span of 25mV at the supply voltage of 10 Vdc. The full-scale output of the sensor changes linearly with supply voltage, so a supply voltage of 5V will return a full-scale span of 12.5 mV. (Vs actual / Vs spec) x Vout full-scale spec = Vout full-scale (5 V/ 10 V) x 25 mV = 12.5 mV SYSTEM DESIGN PRESSURE SENSOR The Motorola Pressure sensor family has three levels of integration - Uncompensated, Compensated and Integrated. For this design, the MPXM2010GS compensated pressure sensor was selected because it has both temperature compensation and calibration circuitry on the silicon, allowing a simpler yet more robust system circuit design. An integrated pressure sensor, such as the MPXV5004G, is also a good choice for the design eliminating the need for the amplification circuitry. Since this application will only be utilizing 40% of the pressure range, 0-4kPa, our maximum output voltage will be 40% of the full-scale span. Vout FS x (Percent FS Range) = Vout max 12.5 mV x 40% = 5.0 mV The package of the pressure sensor is a ported MPAK package. This allows a tube to be connected to the sensor; the tube is connected to the bottom of the tub. This isolates the sensor from direct contact with the water. The small size, and low cost are additional features that make this package a perfect fit for this application. Figure 1. MPXM2010GS/GST1 Case 1320A REV 0 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-395 Freescale Semiconductor, Inc. AN1950 Table 1: MPXM2010D OPERATING CHARACTERISTICS (VS = 10 Vdc, TA = 25C unless otherwise noted, P1 > P2) Symbol Min Typ Max Unit Pressure Range(1) POP 0 -- 10 kPa Supply Voltage(2) VS -- 10 16 Vdc Supply Current Io -- 6.0 -- mAdc VFSS 24 25 26 mV Voff -1.0 -- 1.0 mV Characteristic Full Scale Span(3) Offset(4) Sensitivity V/P -- 2.5 -- mV/kPa Linearity(5) -- -1.0 -- 1.0 %VFSS Freescale Semiconductor, Inc... Amplifier Selection and Amplifier Induced Errors The sensor output needs to be amplified before being inputted directly to the microcontroller through an 8-bit A/D input pin. To determine the amplification requirements, the pressure sensor output characteristics and the 0-5V input range for the A/D converter had to be considered. The amplification circuit uses three op-amps to add an offset and convert the differential output of the MPXM2010GS sensor to a ground-referenced, single-ended voltage in the range of 0 - 5V. The pressure sensor has a possible offset of +/- 1mV at the minimum rated pressure. To avoid a nonlinear response when a pressure sensor chosen for the system has a negative offset (Voff), we have added a 5mV offset to the positive sensor output signal. This offset will remain the same regardless of the sensor output. Any additional offset that the sensor or op-amp introduce is compensated for by software routines that are invoked when the initial system calibration is done. To determine the gain required for the system, the maximum output voltage from the sensor for this application had to be determined. The maximum output voltage from the sensor is approximately 12.5mV with a 5V supply since the full-scale output of the sensor changes linearly with supply voltage. This system will have a maximum pressure of 4kPa at 40cm of water. At a 5V supply, we will have a maximum sensor output of 5mV at 4kPa of pressure. To amplify the maximum sensor output to 5.0V, the following gain is needed: Gain = (Max Output needed) / (Max Sensor Output and Initial Offset) The amplified voltage signal from the positive sensor lead is VB. This amplification adds a small gain to ensure that the positive lead, V2, is always greater than the voltage output from the negative sensor lead, V4. This ensures the linearity of the differential voltage signal. VB = (1+R7/R5) * V2 - (R7/R5) * Vcc = (1+10/1000) * V2 + (10/1000)*(5V) = (1.001) * V2 + .005V The difference between the positive sensor voltage, VB, and the negative sensor voltage, VA is calculated and amplified with a resulting by a gain of 500. VC= (R12/R11) * (VB - VA) = (500K/1K) * (VB - VA) = 500 * (VB - VA) The output voltage, Vc, is connected to a voltage follower. Therefore, the resulting voltage, Vc, is passed to an A/D pin of the microcontroller. The range of the A/D converter is 0 to 255 counts. However, the A/D Values that the system can achieve are dependent on the maximum and minimum system output values: Count = (Vout - VRL) / ( VRH - VRL) x 255 where VXdcr = Transducer Output Voltage Vrh = Maximum A/D voltage Vlh = Minimum A/D voltage Count (0mm H20) = (2.5 - 0) / (5.0 - 0) x 255 = 127 Count (40mm H20) = (5.0 - 0) / (5.0 - 0) x 255 = 255 = 5.0V / (.005V + .005) = 500 The gain for the system was set for 500 to avoid railing from possible offsets from the pressure sensor or the op-amp. The Voltage Outputs from the sensor are each connected to a non-inverting input of an op-amp. Each op-amp circuit has the same resistor ratio. The amplified voltage signal from the negative sensor lead is VA. The resulting voltage is calculated as follows: 3-396 VA= (1+R8/R6) * V4 = (1+10/1000) * V4 = (1.001) * V4 Total # counts = 255 - 127 = 127 counts. The resolution of the system is determined by the mm of water that is represented by each A/D count. As calculate above, the system has a span of 226 counts to represent water level up to and including 40cm. Therefore, the resolution is: Resolution = mm of water / Total # counts = 400mm/127 counts = 3.1 mm per A/D count www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. R6 1K R8 10 W 6 - 7 V4sensor AN1950 5 VA R12 500K + Vcc R11 1K 13 - 4 C5 0.1F 14 R7 10 W Vcc Freescale Semiconductor, Inc... R5 1K V2sensor 2 3 - 12 R9 1K 1 + 9 - 8 VC 10 Vout + 11 R10 500K VB + Figure 2. Amplification Scheme Microprocessor To provide the signal processing for pressure values, a microprocessor is needed. The MCU chosen for this application is the MC68HC908QT4. This MCU is perfect for appliance applications due to its low cost, small 8-pin package, and other on-chip resources. The MC68HC908QT4 provides: a 4 channel, 8-bit A/D, a 16-bit timer, a trimmable internal timer, and in-system FLASH programming. The central processing unit is based on the high performance M68HC08 CPU core and it can address 64 Kbytes of memory space. The MC68HC908QT4 provides 4096 bytes of user FLASH and 128 bytes of random access memory (RAM) for ease of software development and maintenance. There are 5 bi-directional input/output lines and one input line that are shared with other pin features. The MCU is available in 8-pin as well as 16-pin packages in both PDIP and SOIC. For this application, the 8-pin PDIP was selected. The 8-pin PDIP was chosen for a small package, eventually to be designed into applications as the 8-pin SOIC. The PDIP enables the customer to reprogram the software on a programming board and retest. DISPLAY Depending on the quality of the display required, water level and water flow can be shown with 2 LEDs. If a higher quality, digital output is needed, an optional LCD interface is provided on the reference board. Using a shift register to hold display data, the LCD is driven with only 3 lines outputted from the microcontroller: an enable line, a data line, and a clock signal. The two LEDs are multiplexed with the data line and clock signal. EN RS RW PTA3 PTA4 A B LCD CLK PTA5 HC908QT4 HC164 R2 1K DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 R3 1K Figure 3. Multiplexed LCD Circuit Multiplexing of the microcontroller output pins allows communication of the LCD to be accomplished with 3 pins instead of 8 or 11 pins of I/O lines that are usually needed. With an 8-bit shift register, we are able to manually clock in 8 bits of data. The enable line, EN, is manually enabled when 8 bytes have been shifted in, telling the LCD that the data on the data bus is available to execute. The LEDs are used to show pressure output data, by displaying binary values that correspond to a pressure range. Leak Detection or water-flow speed is displayed by blinking a green LED at a speed relating to the speed of water flow. The Red LED will display the direction of water flow. Turning the Red LED off signifies water flowing into the tub. Turning the Red LED on signifies water flowing out of the tub, or there is a leak. Digital values for water height, rate of water flow, and calibration values are displayed if an LCD is connected to the board. OTHER This system is designed to run on a 9V battery. It contains a 5V Regulator to provide 5V to the pressure sensor, microcontroller, and LCD. The battery is mounted on the back of the board using a space saving spring battery clip. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-397 Freescale Semiconductor, Inc. AN1950 Table 2: Parts List Freescale Semiconductor, Inc... Ref Qty. Description Value Vendor Part No. U2 1 Pressure Sensor 1 Motorola C1 1 Vcc Cap 0.1uF Generic C2 1 Op-Amp Cap 0.1uF Generic C3 1 Shift Register Cap 0.1uF Generic D1 1 Red LED Generic D2 1 Green LED Generic S2,S3 2 Pushbuttons Generic U1 1 Quad Op-Amp ADI AD8544 U3 1 Voltage Regulator U4 1 Microcontroller R1 1 R2 1 R3,R6 2 R4,R5 2 R7,R8 2 R9,R10 2 1/4 W Resister 1/4 W Resister 1/4 W Resister 1/4 W Resister 1/4 W Resister 1/4 W Resister U6 1 LCD (Optional) U5 1 Shift Register 5V Fairchild LM78L05ACH 8pin Motorola MC68HC908QT4 22K Generic 2.4K Generic 1.2M Generic 1.5K Generic 10K Generic 1K Generic 16x2 Smart Washer Software This application note describes the first software version that was available. However updated software versions may be available with further functionality and menu selections. MPXM2010GS Seiko L168200J000 Texas Instruments 74HC164 location in memory. To exit the calibration mode, press the SEL (PB1) button. Software User Instructions When the system is turned on or reset, the microcontroller will flash the select LED and display the program title on the LCD for 5 seconds or until the select (SEL) button is pushed. Then the menu screen is displayed. Using the select (SEL) pushbutton, the user can scroll through the menu options for a software program. To run the water level program, use the select button to highlight the "Water Level" option, then press the enter (ENT) pushbutton. The Water Level program will display current water level, the rate of flow, a message if the container is "FILLING", "EMPTYING", "FULL", or "EMPTY", and a scrolling graphical history displaying data points representing the past forty level readings. The Water Level is displayed by retrieving the digital voltage from the internal A/D Converter. This voltage is converted to pressure in millimeters of water and then displayed on the LCD. Calibration and Calibration Software To calibrate the system, a two-point calibration is performed. The sensor will take a calibration point at 0mm and at 40mm of water. Hold down both the SEL and ENT buttons on system power-up to enter calibration mode. At this point, the calibration menu will be displayed with the previously sampled offset voltage. To recalibrate the system, expose the sensor to atmospheric pressure and press the SEL button (PB1). At this point, the zero offset voltage will be sampled and saved to a location in the microcontroller memory. To obtain the second calibration point, place the end of the plastic tube from the pressure sensor to the bottom of a container holding 40mm of water. Then press the ENT button (PB2). The voltage output will be sampled, averaged and saved to a 3-398 -40 cm -35 cm -30 cm -25 cm -20 cm -15 cm -10 cm - 5 cm Figure 4. Water level system set-up for demonstration Converting Pressure to Water Level Hydrostatic Pressure that we are measuring is the pressure at the bottom of a column of fluid caused by the weight of the fluid and the pressure of the air above the fluid. Therefore, the hydrostatic pressure depends on the air pressure, the fluid density and the height of the column of fluid. P= Pa + g h where P = pressure Pa = pressure = mass density of fluid g = 9.8066 m/s^2 h = height of fluid column To calculate the water height, we can use the measured pressure with the following equation, assuming the atmospheric pressure is already compensated for by the selection of the pressure sensor being gauge: h = P \ g www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Software Function Descriptions Freescale Semiconductor, Inc... Main Function The main function calls an initialization function "ALLINIT", calls a warm-up function "WARMUP" to allow extra time for the lcd to initialize, then checks if buttons PB1 and PB2 are being pressed. If they are both pressed, then it calls a calibration function "CALIB". If they are not both pressed, then it enters the main function loop. The main loop displays the menu, moves the cursor when the PB1 is pressed and enters the function corresponding to the highlighted menu option when PB2 is pressed. Calibration Function The calibration function is used to obtain two calibration points. The first calibration point is taken when the head tube is not placed in water to obtain the pressure for 0mm of water. The second calibration point is obtained when the head tube is placed at the bottom of a container with a height of 160mm. When the calibration function starts, a message appears displaying the A/D values for the corresponding calibration points currently stored in the flash. To program new calibration points, the user must press PB1 to take 256 A/D readings at 0mm of water. The average is calculated and stored in a page of flash. Then the user has the option to press PB1 to exit the calibration function or obtain the second calibration point. To obtain the second calibration point, the head tube should be placed in 160mm of water and then the user should press PB2 to take 256 A/D readings. The average is taken and stored in a page of flash. Once the two readings have been taken, averaged, and stored in the flash, a message displays the two A/D values that were stored. Level Function The Level function will initialize the graphics characters. Once this is complete, it will continue looping to obtain an average A/D reading and display the Water Level, the Water Flow, and a Graphical History until the user presses and holds both PB1 and PB2 to return to the main function. The function first clears the 40 pressure readings that it will be updating for the Graphical History. It then enters the loop which first displays 8 special characters, each containing 5 data points of water level history. The function "adcbyta" is called to obtain the current averaged A/D value. The function "LfNx" is called to convert the A/D value to a water level, which is then compared to the Calibration points, the maximum and minimum points, to determine if the container is full or empty. If true, then it displays the corresponding message. The current water level is compared to the previous read and displays the message "filling" if it has increased, "emptying" if it has decreased, and "steady" if it has not changed. The water level calculation has to be converted to decimal in order to display it in the LCD. To convert the water level calculation to decimal, the value is continually divided with the remainder displayed to the screen for each decimal place. To display the Rate of Water Flow, the sign of the value is first determined. If the value is negative, the one's complement is taken, a negative sign is displayed, and then the value is continually divided to display each decimal place. If the number is positive, a plus sign is displayed to maintain the display alignment and the value is continually divided to display each decimal place. Motorola Sensor Device Data AN1950 The most complicated part of this function is updating the graphics history display. The characters for the 16x2 LCD that were chosen for this reference design are 8x5 pixels by default. Therefore, each special character that is created will be able to display 5 water level readings. Since the height of the special character is 8 pixel, each vertical pixel position will represent a water level in increments of 20mm. Resolution = (H1 - H0) / D where H1 and H2 are the maximum and minimum water levels respectively and D is the possible datapoints available per character. Resolution = (160mm - 0mm) / 8 = 20mm / data point. The graphical history is displayed using the 8 special characters. To update the graphics, all the characters have to be updated. The characters are updated by first positioning a pixel for the most recent water level reading in the first column of the first character. Then the four right columns of the first character are shifted to the right. The pixel in the last column of that character is then carried to the first column of the next character. This column shifting is continued until all 40 data points have been updated in the 8 special characters. LfNx Function The LfNx function calculates the water level from the current A/D pressure reading. The A/D Pressure value is stored in Register A before this function is called. Using the A/D value and the calibration values stored in the flash, the water level is calculated from the following function: RBRA: = (NX - N1) * 160 / (N2 - N1), where NX is the current A/D Value N1 is the A/D Value at 0mm H20 N2 is the A/D Value at 160mm H20 To simplify the calculation, the multiplication is done first. Then the function "NdivD" is called to divide the values. NdivD Function The "NdivD" function performs a division by counting successive subtractions of the denominator from the numerator to determine the quotient. The denominator is subtracted from the numerator until the result is zero. If there is an overflow, the remainder from the last subtraction is the remainder of the division. wrflash and ersflsh Functions The "wrflash" and "ersflsh" functions are used to write to and erase values from the flash. For more information regarding flash functionality, refer to Section 4. Flash Memory from the MC68HC908QY4/D Databook. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-399 AN1950 Freescale Semiconductor, Inc. ALLINIT Function The ALLINIT function disables the COP for this version of software, sets the data direction bits, and disables the data to the LCD and turns off the LCD enable line. It also sets up the microcontroller's internal clock to half the speed of the bus clock. See Section 15, Computer Operating Properly, of the MC68908QT4 datasheet for information on utilizing the COP module to help software recover from runaway code. WARMUP Function The WARMUP function alternates the blinking of the two LEDs ten times. This gives the LCD some time to warm up. Then the function "warmup" calls the LCD initialization function, "lcdinit". Freescale Semiconductor, Inc... bintasc Function The "binasc" function converts a binary value to its ascii representation. A/D Functions The A/D functions are used to input the amplified voltage from the pressure sensor from channel 0 of the A/D converter. The function "adcbyti" will set the A/D control register, wait for the A/D reading and load the data from the A/D data register into the accumulator. The function "adcbyta" is used to obtain an averaged A/D reading by calling "adcbyti" 256 times and returning the resulting average in the accumulator. LCD Functions The LCD hardware is set up for multiplexing 3 pins from the microcontroller using an 8-bit shift register. Channels 3, 4, and 5 are used on port A for the LCD enable (E), the LCD reset 3-400 (RS), and the shift register clock bit, respectively. The clock bit is used to manually clock data from channel 4 into the 8-bit shift register. This is the same line as the LCD RS bit because the MSB of the data is low for a command and high for data. The RS bit prepares the LCD for instructions or data with the same bit convention. When the 8 bits of data are available on the output pins of the shift register, the LCD enable (E) is toggled to receive the data. The LCD functions consist of an initialization function "lcdinit" which is used once when the system is started and five output functions. The functions "lcdcmdo" and "lcdchro" both send a byte of data. The function "shiftA" is called by both "lcdcmdo" and "lcdchro" to manually shift 8 bits of data into the shift register. The function "lcdnibo" converts the data to binary before displaying. The "lcdbyto" displays a byte of data by calling "lcdnibo" for each nibble of data. The function "lcdstro" enables strings to be easily added to the software for display. The function accepts a comma-delimited string of data consisting of 1-2 commands for clearing the screen and positioning the cursor. It then continues to output characters from the string until the "@" symbol is found, signally the end of the string. Conclusion The water level reference design uses a MPXM2010GS pressure sensor in the low cost MPAK package, the low cost, 8-pin microcontroller, and a quad op-amp to amplify the sensor output voltage. This system uses very few components, reducing the overall system cost. This allows for a solution to compete with a mechanical switch for water level detection but also offer additional applications such as monitoring water flow for leak detection, and the other applications for smart washing machines. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1950 Freescale Semiconductor, Inc... Software Listing ;NitroWater 2.0 15Nov02 ;-------------- ; ;Water level reference design ;**************************** ; - uses NITRON (MC68HC08QC4) and MPAK (MPXM2010GS) ; CALIB: 2-point pressure calibration (0mm and 160mm) ; LEVEL: displays water level, flow, and graphics ; UNITS: displays A/D value, calib max/min values ;__________________________________________________________ ram equ $0080 ;memory pointers rom equ $EE00 vectors equ $FFDE ;__________________________________________________________ porta equ $00 ;registers ddra equ $04 config2 equ $1E config1 equ $1F tsc equ $20 tmodh equ $23 icgcr equ $36 adscr equ $3C adr equ $3E adiclk equ $3F flcr equ $FE08 flbpr equ $FFBE ;__________________________________________________________ org $FD00 ;flash variables N1 db $96 ;1st calibration pt. = 0mm org $FD40 N2 db $F6 ;2nd calibration pt. = 160mm org $FD80 ;__________________________________________________________ org vectors dw cold ;ADC dw cold ;Keyboard dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;not used dw cold ;TIM Overflow dw cold ;TIM Channel 1 dw cold ;TIM Channel 0 dw cold ;not used dw cold ;IRQ dw cold ;SWI dw cold ;RESET ($FFFE) ;__________________________________________________________ org ram BB ds 1 flshadr ds 2 flshbyt ds 1 memSP ds 2 mem03 ds 2 CNT ds 1 Lgfx ds 1 weath ds 1 ram0 ds 1 NC ds 1 NB ds 1 NA ds 1 DC ds 1 DB ds 1 DA ds 1 MB ds 1 MA ds 1 OB ds 1 OA ds 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-401 Freescale Semiconductor, Inc. AN1950 RB ds 1 RA ds 1 P0C ds 1 P0B ds 1 P0A ds 1 NPTR ds 1 ramfree ds 80 ;used both for running RAM version of wrflash & storing 40 readings ;__________________________________________________________ ;__________________________________________________________ org rom cold: rsp jsr ALLINIT ;general initialization jsr WARMUP ;give LCD extra time to initialize Freescale Semiconductor, Inc... nocalib: MENU: luke: warm: PB1: MENU2: brset brset jmp 1,porta,nocalib 2,porta,nocalib CALIB ;do calibration if SEL & ENT at reset ldhx jsr jsr ldhx jsr jsr #msg01 lcdstro del1s #msg01a lcdstro del1s ldhx jsr clr lda jsr #msg01b lcdstro RA #$0D lcdcmdo ;blink cursor on menu choice ldx clrh lda jsr RA ;get current menu choice menupos,x lcdcmdo ;and look up corresponding LCD address brclr brclr bclr bset jsr bset bclr jsr bra 1,porta,PB1 2,porta,PB2 4,porta 5,porta del100ms 4,porta 5,porta del100ms warm ;wait for SEL ;or for ENT inc lda cmp blt cmp bgt RA RA #$02 PB1ok #$03 menureset ;***SEL*** toggles menu choices ;otherwise skip and show welcome messages ;"Reference Design" msg ;"Water Level" msg ;menu choice=0 to begin with ;toggle LEDs ;delay ;toggle again: SEL ***or*** ENT ;delay and repeat until SEL or ENT ;menu choices are $00 and $01 ; shift up and display 3 ldhx #msg01c jsr lcdstro menureset: PB1ok: PB2: skip00: skip01: 3-402 clr RA ;back to $00 when all others have been offered bclr bclr jsr brclr bra 4,porta 5,porta del100ms 1,porta,PB1ok luke ;LEDs off ;wait a little bit ;make sure they let go of SEL bclr bclr lda cmpa bne jmp cmpa bne jmp cmpa bne 4,porta 5,porta RA #$00 skip00 LEVEL #$01 skip01 UNITS #$02 skip02 ;***ENT*** confirms menu choice ;LEDs off ;get menu choice ;do ===LEVEL=== if choice=$00 ;do ===UNITS=== if choice=$01 ;do ==MANCALIB= if choice=$02 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1950 jmp MANCALIB skip02: jmp TEST ;__________________________________________________________ ;__________________________________________________________ CALIB: ldhx #msg05 ;===CALIB=== 2-point calibration jsr lcdstro ;Calibration current values lda N1 ;0mm jsr lcdbyto lda #'/' jsr lcdchro lda N2 ;160mm jsr lcdbyto bset 4,porta bset 5,porta ;LEDs on lego1: brclr 1,porta,lego1 lego2: brclr 2,porta,lego2 bclr 4,porta bclr 5,porta ;LEDs off when both SEL & ENT are released jsr del1s jsr del1s ;wait 2s ldhx #msg05a jsr lcdstro ;show instructions waitPB1: brset 2,porta,no2 ;if ENT is not pressed, skip jmp nocalib ;if ENT is pressed then cancel calibration no2: brclr 1,porta,do1st ;if SEL is pressed then do 1st point cal bra waitPB1 ;otherwise wait for SEL do1st: ldhx #msg05b ;1st point cal: show values jsr lcdstro clr CNT ;CNT will count 256 A/D readings clr RB clr RA ;RB:RA contains 16-bit add-up of those 256 values do256: lda #$C9 jsr lcdcmdo ;position LCD cursor at the right spot lda CNT deca jsr lcdbyto ;display current iteration $FF downto $00 lda #':' jsr lcdchro jsr adcbyti ;get reading add RA sta RA lda RB adc #$00 sta RB ;add into RB:RA (16 bit add) jsr lcdbyto ;show RB lda RA jsr lcdbyto ;then RA dbnz CNT,do256 ;and do 256x lsl RA ;get bit7 into carry bcc nochg ;if C=0 then no need to round up inc RB ;otherwise round up nochg: lda RB ;we can discard RA: average value is in RB ldhx #N1 ;point to flash location jsr wrflash ;burn it in! ldhx #msg05c ;ask for 160mm jsr lcdstro waitPB2: brset 2,porta,waitPB2 ;wait for ENT ldhx #msg05d ;2nd point cal: show values jsr lcdstro clr CNT ;ditto as 1st point cal clr RB clr RA do256b: lda #$C9 jsr lcdcmdo lda CNT deca jsr lcdbyto lda #':' jsr lcdchro jsr adcbyti add RA sta RA lda RB adc #$00 sta RB Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-403 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1950 jsr lcdbyto lda RA jsr lcdbyto dbnz CNT,do256b lsl RA bcc nochg2 inc RB nochg2: lda RB cmp N1 ;compare N2 to N1 bne validcal ;if different, we are OK ldhx #msg05e ;otherwise warn of INVALID CAL! jsr lcdstro jsr del1s jsr del1s jsr del1s ;wait 2s jmp CALIB ;try cal again validcal: ldhx #N2 jsr wrflash ;burn N2 into flash ldhx #msg05 ;and display new current cal values from flash jsr lcdstro lda N1 ;0mm value jsr lcdbyto lda #'/' jsr lcdchro lda N2 ;160mm value jsr lcdbyto jsr del1s jsr del1s jmp nocalib ;done! ;__________________________________________________________ LEVEL: lda #$01 ;===LEVEL=== main routine: displays level, flow & graphics jsr lcdcmdo ;clear screen lda #$0C jsr lcdcmdo ;cursor off fillgfx: LVL: purge: LVLwarm: lda jsr clra jsr inca cmp bne lcdchro ;position cursor at LCD graphics portion ;(2nd half of first line) ;and write ascii $00 through $07 ;which contain the graphics related to ;40 different readings #$08 fillgfx ldhx lda clr incx dbnza jsr jsr sta #ramfree #$28 0,x purge adcbyta LfNx Lgfx ;store in "Level graphics" bset bset 4,porta 5,porta ;LEDs on during this cycle ldhx mov shiftgfx: lda sta incx dbnz lda jsr lda jsr jsr mov clr cmp bcs cmp bcc clrh ldx div mov 3-404 #$88 lcdcmdo #ramfree #$27,RA 1,x 0,x RA,shiftgfx #$80 lcdcmdo Lgfx adcbyta LfNx RA,OA RB #$03 Lzero #$9E Lsat #$14 ;point to 40 pressure readings ;count down from 40 ;clear all those locations ;next (H cannot change: we are in page0 RAM) ;get Lref: reference A/D reading ;point to 40 pressure readings ;count down from 39 ;take location+1 ;and move to location+0, i.e. shift graphics left ;next X (once again: we are in page 0, no need to worry about H) ;do this 39x ;get averaged A/D reading (i.e. LX) ;LX:=(NX-N1)*160/(N2-N1) ;if <=2mm ;then "empty" ;then "full" ;div by 20 #$01,RB www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. makeRB Lsat: Lzero: cmp beq lsl dbnza bra mov lda ldhx sta #$01 Lzero RB makeRB Lzero #$80,RB RB #ramfree+$27 0,x clr lda beq cmp bne mov bra mov lda cmp beq mov bcc mov weath RB donew #$80 notfull #$01,weath donew #$02,weath OA Lgfx donew #$03,weath donew #$04,weath lda sub sta mov OA Lgfx MA RA,Lgfx ;rate:=L(i)-L(i-1) ;update L(i-1) lda jsr #$80 lcdcmdo ;******** now let's display the level in decimal ******** ;start on 1st character of 1st line lda clrh ldx clr div bne lda jsr bra jsr inc pshh pula clrh ldx div bne tst bne lda jsr bra jsr pshh pula jsr lda jsr lda jsr OA AN1950 ;last of the 40 ;put it at then end of the 40 bytes (new value), all others were shifted left Freescale Semiconductor, Inc... notfull donew: over100: lnext: nospace: lnexta: ;$00 if "empty" ;set "full" if $80 ;prepare for "steady" if L(i)=L(i-1) ;"filling" if L(i)>L(i-1) ;"emptying" otherwise #$64 RB over100 #$20 lcdchro lnext lcdnibo RB ;prepare for a space in case first value is 0 #$0A ;divide by 10 nospace RB nospace #$20 lcdchro lnexta lcdnibo ;display tens digit lcdnibo #'m' lcdchro #'m' lcdchro ;and first decimal lda jsr lda lsla bcc #$C0 lcdcmdo MA ;******** now let's display the flow in decimal ******** ;position cursor on 1st character 2nd line positiv ;test sign of rate (in MA) ;if positive, then it's easy lda coma inca sta lda jsr MA ;otherwise 1's complement of MB MA #'-' lcdchro ;display that minus sign Motorola Sensor Device Data ;then the unit www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-405 Freescale Semiconductor, Inc. AN1950 positiv: bra goconv lda jsr #'+' lcdchro Freescale Semiconductor, Inc... goconv: lda clrh ldx clr div bne lda jsr bra over100b: jsr inc lnextb: pshh pula clrh ldx div bne tst bne lda jsr bra nospaceb: jsr lnextab: pshh pula jsr lda jsr lda jsr lda jsr lda jsr cg8: ;display the plus sign (to keep alignment) MA #$64 RB over100b #$20 lcdchro lnextb lcdnibo RB ;prepare for a space in case first value is 0 #$0A ;divide by 10 nospaceb RB nospaceb #$20 lcdchro lnextab lcdnibo ;display tens digit lcdnibo #'m' lcdchro #'m' lcdchro #'/' lcdchro #'s' lcdchro ;and first decimal ;then the unit lda jsr ldhx mov lda sta lda sta lda sta lda sta lda sta #$40 lcdcmdo #ramfree #$08,DA 0,x NC 1,x NB 2,x NA 3,x DC 4,x DB ;======== Graphics Update: tough stuff =========== ;prepare to write 8 bytes into CGRAM starting at @ $40 ;point to 40 pressure readings (this reuses wrflash RAM) ;DA will count those 8 CGRAM addresses mov clr rol rol rol rol rol rol rol rol rol rol lda jsr dec bne incx incx incx incx incx #$08,RA RB NC RB NB RB NA RB DC RB DB RB RB lcdchro RA fill ;RA will count the 8 bits ;start with RB=0, this will eventually contain the data for CGRAM ;readings 0-4 go into NC,NB,NA,DC,DB and will form 1 LCD special charac- ter fill: ;rotate left those 5 values and use carry bits to form RB (tough part) ;and put it into CGRAM ;do this 8 times to cover all 8 bits ;now point to next 5 values for next CGRAM address (5 values per charac- ter) 3-406 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... dec bne DA cg8 AN1950 ;do this for all 8 CGRAM characters lda weath ;get weather variable and decide which message to display cmp #$04 bne try3210 ldhx #msg02e ;if $04 bra showit try3210: cmp #$03 bne try210 ldhx #msg02d ;if $03 bra showit try210: cmp #$02 bne try10 ldhx #msg02c ;if $02 bra showit try10: cmp #$01 bne try0 ldhx #msg02b ;if $01 bra showit try0: ldhx #msg02a ;otherwise this one showit: jsr lcdstro jsr del1s ;1s between pressure/altitude readings brset 1,porta,contin ;exit only if SEL brset 2,porta,contin ;and ENT pressed together jmp MENU contin: jmp LVLwarm ;__________________________________________________________ LfNx: sub N1 ;*** PX=f(NX,N2,N1) *** ldx #$A0 ;x160 mul sta NA stx NB clr NC ;NCNBNA:=(NX-N1)*160 lda sub sta clr clr jsr lda N2 N1 DA DB DC NdivD RA ;RBRA:=(NX-N1)*160/(N2-N1) rts ;__________________________________________________________ NdivD: clr RA ;RBRA:=NCNBNA/DCDBDA clr RB ;destroys NCNBNA and DCDBDA keepatit: lda RA add #$01 sta RA lda RB adc #$00 sta RB ;increment RB:RA lda NA sub DA sta NA lda NB sbc DB sta NB lda NC sbc DC sta NC ;NC:NB:NA:=NC:NB:NA-DC:DB:DA bcc keepatit ;keep counting how many times until overflow lda RA sub #$01 sta RA lda RB sbc #$00 sta RB ;we counted once too many, so undo that lsr DC ror DB ror DA ;divide DC:DB:DA by 2 lda NA add DA sta NA lda NB Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-407 Freescale Semiconductor, Inc. AN1950 adc DB sta NB lda NC adc DC sta NC ;and add into NC:NB:NA lsla bcs nornd ;if carry=1 then remainder<1/2 of dividend lda RA add #$01 sta RA lda RB adc #$00 sta RB ;otherwise add 1 to result nornd: rts ;__________________________________________________________ UNITS: lda #$01 ;===UNITS=== : displays A/D value, calib max/min values jsr lcdcmdo ;clear screen Freescale Semiconductor, Inc... UNTwarm: lda jsr #$0C lcdcmdo ;cursor off lda jsr jsr #$80 lcdcmdo adcbyta ;(pos cursor begining of first line) ;get Lref: reference A/D reading bset jsr jsr bclr 4,porta lcdbyto del1s 4,porta ;SEL LED-ON signals getting reading jsr adcbyta ;get Lref: reference A/D reading sub N1 ;*** PX=f(NX,N2,N1) *** cmp bgt lda jsr lda jsr bra #$00 skipzero #'-' lcdbyto #'-' lcdbyto skipneg ; IF Nx - N1 > 0 then calculate ldx mul sta stx clr lda jsr jsr #$A0 ;x160 NA NB NC #$90 lcdcmdo lcdbyto ;(pos cursor 2nd half of first line) ; display NA lda jsr lda jsr #$87 lcdcmdo NB lcdbyto ; jsr del1s ;1s between pressure/altitude readings ;SEL LED-OFF signals reading received tstLfNx: ; Else IF Nx << N1 then display error message to recalibrate skipzero: ;NCNBNA:=(NX-N1)*160 display NB skipneg: brset 1,porta,UNTcon ;exit only if SEL brset 2,porta,UNTcon ;and ENT pressed together jmp MENU UNTcon: jmp UNTwarm ;__________________________ MANCALIB: jsr del1s rts TEST: jsr del1s 3-408 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1950 rts ;__________________________________________________________ wrflash: sthx flshadr ;this is the address in the flash sta flshbyt ;and the byte we want to put there FLASH: tsx sthx memSP ;store SP in memSP, so it can be temporarily used as a 2nd index register ldhx #ramfree+1 ;SP now points to RAM (remember to add 1 to the address!!!, HC08 quirk) txs ;SP changed (careful not to push or call subroutines) ldhx #ersflsh ;H:X points to beginning of flash programming code doall: lda 0,x ;get 1st byte from flash sta 0,sp ;copy it into RAM aix #$0001 ;HX:=HX+1 ais #$0001 ;SP:=SP+1 cphx #lastbyt ;and continue until we reach the last byte bne doall ldhx memSP ;once done, restore the SP txs jsr ramfree ;and run the subroutine from RAM, you cannot write the flash while rts ;running a code in it, so the RAM has to take over for that piece ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ersflsh: lda #$02 ;textbook way to erase flash sta flcr lda flbpr clra ldhx flshadr sta 0,x bsr delayf lda #$0A sta flcr bsr delayf lda #$08 sta flcr bsr delayf clra sta flcr bsr delayf pgmflsh: lda #$01 ;textbook way to program flash sta flcr lda flbpr clra ldhx flshadr sta 0,x bsr delayf lda #$09 sta flcr bsr delayf lda flshbyt ldhx flshadr sta 0,x bsr delayf lda #$08 sta flcr bsr delayf clra sta flcr bsr delayf rts delayf: ldhx #$0005 mov #$36,tsc ;stop TIM & / 64 sthx tmodh ;count H:X x 20us bclr 5,tsc ;start clock delayfls: brclr 7,tsc,delayfls rts lastbyt: nop ;-------- GENERAL Routines ------------------------------------------ ALLINIT: bset 0,config1 ;disable COP mov #$38,ddra ;PTA0=MPAK,PTA1=SEL,PTA2=ENT,PTA3=E,PTA4=RS,PTA5=clk bclr 3,porta ;E=0 bclr 4,porta ;grn=OFF; RS=0 bclr 5,porta ;red=OFF; CLK=0 mov #$30,adiclk ;ADC clock /2 rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - WARMUP: bclr 4,porta Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-409 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1950 bclr lda tenx: jsr bclr bset jsr bset bclr dbnza jsr bclr bclr rts ;- - - - - - - - bintasc: add cmp bls add d0to9b: rts ;- - - - - - - - del1s: pshh pshx ldhx bra del100ms: pshh pshx ldhx bra del50ms: 5,porta #$0A del25ms 4,porta 5,porta del25ms 4,porta 5,porta tenx lcdinit 4,porta 5,porta ;LEDs off #$C350 delmain #$1388 delmain pshh pshx ldhx bra #$04E2 delmain pshh pshx ldhx bra #$00FA delmain pshh pshx ldhx bra #$0032 delmain del100us: pshh pshx ldhx bra #$0005 delmain del1ms: ;and off/on ;10 times so the LCD can get ready (slow startup) ;now initialize it - - - - - - - - - - - - - - - - - - - - - - - - - - #$09C4 delmain del5ms: ;alternate on/off - - - - - - - - - - - - - - - - - - - - - - - - - - #$30 ;add $30 (0-9 offset) #$39 ;is it a number (0-9) ? d0to9b ;if so skip #$07 ;else add $07 = total of $37 (A-F offset) pshh pshx ldhx bra del25ms: ;LEDs off ;prepare to do this 10x ;delay delmain: mov #$36,tsc ;stop TIM & / 64 sthx tmodh ;count H:X x 20us bclr 5,tsc ;start clock delwait: brclr 7,tsc,delwait pulx pulh rts ;-------- A/D Routines ---------------------------------------------- adcbyti: mov #$00,adscr ;ADC set to PTA0 brclr 7,adscr,* ;wait for ADC reading lda adr rts ;;;;;;;;;;;;;;;;;;;;;;;;;; adcbyta; clr CNT ;average 256 readings clr RB clr RA do256a: bsr adcbyti add RA sta RA lda RB adc #$00 sta RB 3-410 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN1950 dbnz CNT,do256a lsl RA bcc nochga inc RB nochga: lda RB rts ;-------- LCD Routines ---------------------------------------------- lcdinit: lda #$3C bsr lcdcmdo lda #$0C bsr lcdcmdo lda #$06 bsr lcdcmdo lda #$01 bsr lcdcmdo rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lcdcmdo: bsr shiftA bclr 4,porta ;RS=0 for command bset 3,porta bclr 3,porta ;toggle E bsr del5ms rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lcdchro: bsr shiftA bset 4,porta ;RS=1 for data bset 3,porta bclr 3,porta ;toggle E bsr del100us rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - shiftA: psha mov #$08,BB all8: lsla bcc shift0 shift1: bset 4,porta bra shift shift0: bclr 4,porta shift: bclr 5,porta bset 5,porta bclr 5,porta ;toggle CLK dbnz BB,all8 pula rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lcdnibo: psha jsr bintasc ;convert binary to asc bsr lcdchro pula rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lcdbyto: psha psha lsra lsra lsra lsra bsr lcdnibo ;high nibble pula and #$0F bsr lcdnibo ;low nibble pula rts ;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - lcdstro: psha lda 0,x lcon: cmp #$80 bhs iscmd cmp #$1F bls iscmd isdta: bsr lcdchro ;output it to LCD reuse1: aix #$0001 lda 0,x ;indexed by y cmp #$40 ;continue until bne lcon ;character = '@' Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-411 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... AN1950 pula bclr 4,porta bclr 5,porta rts iscmd: bsr lcdcmdo bra reuse1 ;-------- ROM Data -------------------------------------------------- msg01 db $01,$80,'*NITRON & MPAK* ' db $C0,'Reference Design','@' msg01a db $01,$80,'Water Level & ' db $C0,'Flow v2.0','@' msg01b db $01,$80,'1:Level/Flow ' db $C0,'2:A/D sys demo','@' msg01c db $01,$80,'1:Level/Flow ' db $C0,'2:A/D sys demo','@' msg05 db $01,$80,'* Calibration! *' db $C0,'Curr lo/hi:','@' msg05a db $01,$80,'1st point: 0mm' db $C0,'SEL:cal ENT:quit','@' msg05b db $01,$80,'Calibrating... ' db $C0,' 0mm: ','@' msg05c db $01,$80,'2nd point: 160mm' db $C0,'ENT:continue ','@' msg05d db $01,$80,'Calibrating... ' db $C0,' 160mm: ','@' msg05e db $01,$80,'INVALID ' db $C0,'CALIBRATION! ','@' msg02a db $C8,' EMPTY','@' msg02b db $C8,' FULL','@' msg02c db $C8,' steady','@' msg02d db $C8,' filling','@' msg02e db $C8,'emptying','@' menupos db $80,$C0 end References 1) Baum, Jeff, "Frequency Output Conversion for MPX2000 Series Pressure Sensors," Motorola Application Note AN1316/D. 2) Hamelain, JC, "Liquid Level Control Using a Motorola Pressure Sensor," Motorola Application Note AN1516/D. 3-412 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Freescale Semiconductor, Inc... New Small Amplified Automotive Vacuum Sensors A Single Chip Sensor Solution for Brake Booster Monitoring AN4007 Prepared by: Marc Osajda Automotive Sensors Marketing Sensor Products Division Motorola Semiconductors S.A. Toulouse France BRAKING SYSTEMS BRAKE BOOSTER OPERATION PRINCIPLE Different types of braking principles can be found in vehicles depending on whether the brake system is only activated by muscular energy or power assisted (partially or completely). Muscular activated brakes are mostly found on motorcycles and very light vehicles. The driver's effort on the hand lever or pedal is directly transmitted via a hydraulic link to the brake pads. Power assisted brakes are found on most passenger cars and some light vehicle trucks. In this case, the driver's effort is amplified by a brake booster to increase the force applied to the brake pedal. The vacuum brake booster is a system using the differential between atmospheric pressure and a lower pressure source (vacuum) to assist the braking operation. The brake booster is located between the brake pedal and the master cylinder. Figure 1 shows a simplified schematic of a vacuum brake booster. When no brake pressure is applied on the push rod (brake pedal side), the air intake valve is closed and the vacuum valve open. Thus, both the vacuum and working chambers are at the same pressure, typically around -70 kPa (70 kPa below atmospheric pressure). Vacuum is generated by either the engine intake manifold or by an auxiliary vacuum pump. RUBBER MEMBRANE PISTION CONNECTION TO VACUUM PUMP OR ENGINE INTAKE MANIFOLD PUSH ROD TO MASTER CYLINDER PUSH ROD FROM THE BRAKE PEDAL AIR INTAKE VALVE VACUUM VALVE VACUUM CHAMBER WORKING CHAMBER Figure 1. Brake Booster Simplified Schematic REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-413 Freescale Semiconductor, Inc. AN4007 Pv Fp + Fb Once the brake pedal is activated (force Fp), the vacuum valve is closed and the air intake valve is open proportionally to the displacement of the push rod (Figure 2). The working chamber is progressively open to atmospheric pressure, which creates a differential between the vacuum chamber and the working chamber. This differential pressure applied to the surface (S) of the piston results in a force Fb = (Pw - Pv) x S. The forces Fb + Fp are then applied to the brake pads through the master cylinder and hydraulic links. When the brake pedal is released, the spring moves the piston back, closing the air intake valve and opening the vacuum valve to rebalance the pressure between the two chambers. Pw Fp Freescale Semiconductor, Inc... Figure 2. Braking Phase VACUUM GENERATION On most passenger cars, vacuum is generated by the engine itself. When the engine throttle valve is closed, the displacement of the pistons produces vacuum in the intake manifold. Thanks to a tube or hose connected between the engine intake manifold and the brake booster, vacuum can be applied to the chambers. A backslash valve inserted between the intake manifold and the booster maintains the vacuum in the booster when the engine throttle valve is open. This principle has some limitations, however. For example, it can be only used on engines that have the ability to generate enough vacuum. On diesel engines, which have no throttle valve, it is necessary to use an auxiliary pump to generate vacuum. This will also be the case on the Gasoline Direct Injection (GDI) engine, where in some driving conditions (idle, lean burn) the electrically assisted throttle valve will be maintained slightly open. In this situation, the vacuum available on the intake manifold is not sufficient to provide an efficient braking. BUS INTERFACE PUMP CONTROL CIRCUIT PRESSURE SENSOR VACUUM FEEDBACK ELECTRICAL VACUUM PUMP VACUUM GENERATION Figure 3. Vacuum Pump Monitoring Therefore, it is necessary and desirable to use an electrical pump that will generate the vacuum for the brake booster. The use of an auxiliary electrical pump (Figure 3) provides several advantages over the "intake manifold" vacuum. * Vacuum generation is no longer related to the engine running condition. Vacuum is only generated and controlled by the pump thanks to a vacuum pressure sensor that provides an accurate reading to the pump electrical control circuit. * The electrical pump can be switched on and off based on the required vacuum. To compensate atmospheric pressure variation in order to maintain a constant booster effect, the pump also can be switched on independently from the atmospheric pressure. Various algorithms for driving the pump can be implemented depending on the required braking conditions. 3-414 * Pressure variations during braking can be measured, and the pump can be activated to generated additional vacuum if required to increase the braking force. * Leakage can be detected by the pressure sensors and the pump can be switched on to compensate them. The driver can be informed of any type of failure thanks to the bus interface. Vacuum level, and thus available braking force can be communicated through the bus to other braking systems such as, for example, ABS or ESP. Motorola, a worldwide leader in automotive semiconductors, has introduced a new integrate pressure sensor dedicated to vacuum measurements in applications such as brake booster monitoring. The single-chip vacuum sensor may be placed directly onto the pump electronic control unit or integrated as component within the brake booster, thus providing flexibility, system integration and reduced system cost. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. taps. To get an accurate pressure reading, such a sensing element needs usually to be calibrated, temperature compensated and amplified. In order to solve the inherent limitation of the basic sensing element, Motorola produces an entire family of calibrated, thermally compensated and amplified pressure sensors (Figure 4) called Integrated Pressure Sensors (IPS). The IPS is a state of the art, monolithic, amplified and signal-conditioned silicon pressure sensor. The sensor combines advanced micromachining techniques, thin film memorization and bipolar semiconductor processing to provide an accurate, high-level analog output that is proportional to the applied pressure. IPS sensors can be directly connected to an A/D converter. Motorola's New MPXV6115VC6U Vacuum Sensor PIEZORESISTIVE/AMPLIFIED SENSORS Freescale Semiconductor, Inc... Motorola's pressure sensors are based on a piezoresistive technology that consists of a silicon micromachined diaphragm and a diffused piezoresistive strain gauge. When vacuum or pressure is applied on the die, the diaphragm is deformed and stressed. The resulting constraints create a variation of resistance in the piezoresistive strain gauge. In order to read this variation, an excitation current passes through the gauge, and a voltage proportional to the applied pressure and excitation current appears between the voltage P THERMAL COMPENSATION SENSING ELEMENT AN4007 AMPLIFIER V Figure 4. Integrated Pressure Sensor Block Diagram PRESSURE MEASUREMENT CONVENTION Pressure measurements can be divided into three different categories: absolute, gage and differential pressure. Absolute pressure refers to the absolute value of the force per unit area exerted on a surface by a fluid. Therefore, the absolute pressure is the difference between the pressure at a given point in a fluid and the absolute zero of pressure or a perfect vacuum. Gage pressure is the measurement of the difference between the absolute pressure and the local atmospheric pressure. Local atmospheric pressure can vary depending on ambient temperature, altitude and local weather conditions. GAGE (+) The standard atmospheric pressure at sea level and 20_C is 101.325 kPa absolute. When referring to pressure measurement, it is critical to specify what reference the pressure is related to: gage or absolute. A gage pressure by convention is always positive. A `negative' gage pressure is defined as vacuum. Figure 5 shows the relationship between absolute, gage pressure and vacuum. Differential pressure is simply the measurement of one unknown pressure with reference to another unknown pressure. The pressure measured is the difference between the two unknown pressures. Since a differential pressure is a measure of one pressure referenced to another, it is not necessary to specify a pressure reference. LOCAL ATMOSPHERIC PRESSURE VACUUM (-) ABSOLUTE ATMOSPHERIC ABSOLUTE Figure 5. Pressure Convention Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-415 Freescale Semiconductor, Inc. AN4007 TRANSFER FUNCTION The behavior of an IPS is defined by a linear transfer function. This transfer function applies to all Motorola's Integrated Pressure Sensors whatever the pressure range and type of sensing element (absolute or differential). V out + V (P " (PE S K1 ) K2) TM VS The variables P and Vs are dependent on the user application but must remain within the operating specification of the device. THE MPXV6115VC6U INTEGRATED PRESSURE SENSOR The Motorola MPXV6115VC6U gauge vacuum sensor, designed to measure pressure below the atmospheric pressure, is suitable for automotive application such as vacuum pump or brake booster monitoring. The MXPV4115V is also ideal for non-automotive applications where vacuum control is required. The MPXV6115VC6U has the following basic characteristics (Note: Detailed characteristics of Motorola's pressure sensors can be found on http://www.motorola.com/semiconductors). K1) * Vout : Sensor output voltage * P: Applied pressure in kPa * Vs: Sensor supply voltage in V * K1: Sensitivity constant in V/V/kPa * K2: Offset Constant inV/V MPXV6115VC6U CHARACTERISTICS * TM: Temperature multiplier V out The constants, K1, K2, PE & TM are specific to each device, temperature and pressure encountered in the application. + V (P " (PE S 0.007652 TM VS ) 0.92) 0.007652) 5 TRANSFER FUNCTION: Vout = 2.30 V @ P = -60 kPa 4 Vout = VS ([0.007652 *P] + 0.92) REFERENCE: ATMOSPHERIC PRESSURE TYPICAL V out IN VOLTS @ VS = 5 Vdc Freescale Semiconductor, Inc... * PE: Pressure error in kPa 3 2 VACUUM 1 0 -120 -100 -80 -60 -40 -20 0 20 VACUUM in kPa (below atmospheric pressure) Figure 6. MPXV6115VC6U Transfer Function * P is the applied vacuum to the sensor pressure port. Pressures below atmospheric pressure have a negative sign. For example, 50 kPa below atmospheric is P = -50 in the transfer function. For pressure higher than the atmospheric pressure, the device will electrically saturate. The sensor is designed to measure vacuum from 0 kPa (Atmospheric pressure applied to the sensor pressure port) down to - 115kPa. Since the MPXV6115VC6U is using the atmospheric pressure as reference, -115 kPa can only be reached if the atmospheric pressure is higher or equal than 115 kPa. The device will electrically saturate for vacuum below -115 kPa. * PE = 1.725 kPa (1.5% of full scale span) over the entire pressure range 3-416 * TM = 1 between 0 and +85_C, 3 at -40_C and +125_C. TM is a linear response from -40_ to 0_C and from 85_ to 125_C. The real intent for the pressure-sensor user is to know the measured pressure. In this case it is preferable to express the transfer function as: P + (VoutV * 0.92) 0.007652 " (PE S TM) As an example, if Vout = 2.30 V for a 5 Vdc power supply and at 25_C ambient temperature, the measured vacuum is P = -60.1 kPa 1.725 kPa. " www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. SENSOR PACKAGING The packaging of a pressure sensor die is critical to achieve optimal performances of the final product. The package must isolate the pressure sensor die from unwanted external stress which can cause undesired drift of the electrical signal while being robust enough to support the pressure applied to the device without cracks, leaks or mechanical failures. It must be media compatible for the same reasons. APPLIED PRESSURE (OR VACUUM) CUSTOMER PRESSURE PORT FLAT RING Freescale Semiconductor, Inc... EEEEEE EEEEEE APPLICATION HOUSING SOP PACKAGE CASE 482 PRINTED CIRCUIT BOARD SNAP-FIT Figure 7. Mounting Suggestion Motorola Sensor Device Data SCREW AN4007 The new small pressure sensor package from Motorola addresses those requirements and lets designers mount a pressure sensor directly on a printed circuit board, thus providing great flexibility for space saving design. Figure 7 shows a typical assembly using a small outline package (SOP) Case 482-01. The sensor can be mounted on the printed circuit board by an automatic pick and place machine as with every other surface mount component. Sealing is done by using a silicone flat ring inserted in the application housing. The printed circuit board must be maintained against the flat ring either by a snap fit, or by a screws as shown. The new small outline package (SOP) is fabricated using poly-phenyl sulfide (PPS), a robust material, which can withstand high temperatures and is highly resistant to chemicals. Consequently, the package is ideal for harsh environment such as automotive, industrial or medical systems. The small outline package is suitable for any of Motorola's sensor chips from the basic uncompensated sensor to the fully integrated sensing solution that include amplifiers and other circuitry all on one chip. Motorola's sensors using this package are available in both tubes and tape and reel configuration for high productivity on your assembly line. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-417 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE Low-Pressure Sensing Using MPX2010 Series Pressure Sensors AN4010 Prepared by: Memo Romero and Raul Figueroa Motorola Sensor Products Division Systems and Applications Engineering Freescale Semiconductor, Inc... INTRODUCTION This application note presents a design for a low pressure evaluation board using Motorola MPX2010 series pressure sensors. By providing large gain amplification and allowing for package flexibility, this board is intended to serve as a design-in tool for customers seeking to quickly evaluate this family of pressure sensors. The MPX2010 family of pressure sensors appeals to customers needing to measure small gauge, vacuum, or differential pressures at a low cost. However, different applications present design-in challenges for these sensors. For very low pressure sensing, large signal amplification is required, with gains substantially larger than what is provided in Motorola's current integrated pressure sensor portfolio. In terms of packaging, customers often need more mechanical flexibility such as smaller size, dual porting or both. In many cases, customers often lack the engineering resources, time or expertise to evaluate the sensor. The low-pressure evaluation board, shown in Figure 1, facilitates the design-in-process by providing large signal gain and by providing for different package designs in a relatively small footprint. CIRCUIT DESCRIPTION For adequate and stable signal gain and output flexibility, a two-stage differential op-amp circuit with analog or switch output is utilized, as shown in Figure 2. The four op-amps are packaged in a single 14 pin quad package. There are several features to note about the circuitry. The first gain stage is accomplished by feeding both pressure sensor outputs (VS- & VS+) into the non-inverting inputs of operational amplifiers. These op-amps are used in the standard non-inverting feedback configuration. With the condition that Resistors R2=R3, and R1=R4 (as closely as possible), this configuration results in a gain of G1= R4/R3+1. The default gain is 101, but there are provisions for easily changing this value. The signal V (op-amp Pin 7) is then calculated as: V1 = G1*(VS+ - VS-) + Voffset. ....Equation (1) Figure 1. Low Pressure Evaluation Board 3-418 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. AN4010 Figure 2. Circuit Schematic Voffset is the reference voltage for the first op-amp and is pre-set with a voltage divider from the supply voltage. This value is set to be 6.7 percent of the supply voltage. It is important to keep this value relatively small simply because it too is amplified by the second gain stage. It is also desirable to have resistors R7 and R8 sufficiently large to reduce power consumption. The second gain stage takes the signal from the first gain stage, V, and feeds it into the non-inverting input of a single op-amp. This op-amp is also configured with standard non-inverting feedback, resulting in a gain of G2=R5/R6+1. The default value is set to 2, but can easily be changed. The signal produced at the output of the second stage amplifier, V (op-amp pin 8) is the fully amplified signal. This is calculated as V2 = G2* V1. ....Equation (2) Figure 3. Analog Output Jumper Settings From this point, there are two possible output types available. One is a simple follower circuit, as shown in Figure 3, in which the circuit output, Vout (op-amp pin 14), is essentially a buffered V signal. This analog output option is available for applications in which the real time nature of the pressure signal needs to be measured. This option is selected by connecting jumpers J5 and J6. J4 and J7 are not connected for analog output. The second output choice, a switch output as shown in Figure 4, is accomplished by setting jumpers J4 and J7, and leaving J5 and J6 unconnected. This is appropriate for applications in which a switching function is desired. In this case, the fourth op-amp is configured as a comparator, which will invert V2, high or low, depending on whether V2 is larger or smaller than the preset reference signal, set by trim-pot R9. This signal can be used to simulate a real world threshold. Figure 4. Switch Output Jumper Settings Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-419 Freescale Semiconductor, Inc. AN4010 Table 1 shows the jumper settings for both analog and switches outputs. AAAAA AAA AAA AAA AAA AAAAA AAA AAA AAA AAA AAAAA AAA AAA AAA AAA AAAAA AAA AAA AAA AAA Table 1. Output Jumper Settings Output JP4 JP5 JP6 JP7 Analog Out In In Out Switch In Out Out In Freescale Semiconductor, Inc... For the switch output option, it is desirable to apply some hysteresis on the output signal to make it relatively immune to potential noise that may be present in the voltage signal as it reaches and passes the threshold value. This is accomplished with feedback resistor R10. From basic op-amp theory, it can be shown that the amount of hysteresis is computed as follows: VH = Vout *[1-(10 / ( R10 + R pot-eff))] Where: - VH is the output voltage attenuation, due to hysteresis, in volts - Vout is the output voltage (railed hi or low) - R10 is the feedback resistor, = 50K - Rpot-eff is the effective potentiometer resistance VH may vary depending on the particular value of the potentiometer. To take an example, suppose that the supply voltage, Vs is 5 volts, and the threshold is set to 60 percent of Vs, or 3 volts. This corresponds to one leg of the 1K potentiometer set to 0.4K while the other is set to 0.6K. Thus the effective pot resistance is 0.4K // 0.6K = 0.24K. Therefore, VH = 5V* [1- (50K/(50K + 0.24K))] = 24 mV. Under these conditions, V signals passing through the threshold will not cause Vout to oscillate between Vs and Ground as long as noise and signal variations in V are less than 24mV during the transition. Figure 5. Illustrates the benefit of having a hysteresis feedback resistor. GAIN CUSTOMIZATION The low-pressure evaluation board comes with default gains for both G1 and G2. G1 is factory set at 101, while G2 is set to 1. Jumpers JP1, JP2 and JP3 physically connect the resistors that produce these default gains. Three resistor sockets (R11, R41 and R51) are provided in parallel with R1, R4 and R5, respectively. By removing jumpers JP1,JP2 and JP3, and soldering different resistor values in the appropriate sockets, different gain values can be achieved. The limit on the largest overall gain that can be used is determined by op-amp saturation. Thus if gain values are chosen such that the output would be larger than the supply voltage, then the op-amp would saturate, and the pressure would not be accurately reflected. Table 2 outlines the jumper settings for customizing the gain. Table 2. Resistor and Jumper Settings for Gain Customization AAAA AAA AAAA AAAAA AAAA AA AAA AAA AA AAA AA AAA AA AAAA AAAA AAAA AAAAA AA AAA AAA AA AAA AA AAA AA AAAA AA AAA AAA AA AAA AA AAA AA AAAA AAA AAA AAA AAA AAAA AA AA AA AA AA AAA AAA AA AAA AA AAA AA AAAA AA AA AA AAA AA AAA AAA AAA AAA AAAA AA AAA AAA AA AAA AA AAA AA AAAA AA AA AA AA AAA AAA AAA AAA AAAA AA AAA AAA AA AAA AA AAA AA AAAA Gain Figure 5a. Output Transition without Hysteresis Resistors Jumpers Remarks G1 G2 R11 R41 R51 JP1 JP2 JP3 101 2 no load no load no load In In In Default User Set 2 load load no load Out Out In R11=R41 101 User Set no load no load load In In Out User Set User Set load load load Out Out Out R11=R41 DESIGN CONSIDERATIONS Figure 5b. Output Transition with Hysteresis 3-420 Since the evaluation board is primarily intended for low-pressure gage and differential applications, large gain values can be utilized for pressures less than 1.0 kPa. For example if G1 is set to 101, and G2 set to 6, then the total gain is 606. Inherent in the MPX2010 family of pressure sensors is a zero-pressure offset voltage, which can be up to 1 mV. This offset is amplified by the circuit and appears as a DC offset at Vout with no pressure applied. The op-amp also has a voltage offset specification, though for the recommended op-amp this value is small and does not contribute significantly to the Vout offset. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. For example, if the evaluation board is being used under the following conditions: Vs = 3V G1 = 101 G2 = 6 MPX2010 zero pressure offset = 0.3mV At this supply voltage, VOFFSET can be calculated to be 6.7% x 3V = 0.2V. The voltage V, due simply to the zero pressure sensor offset voltage of 0.3mV, can be calculated from equation (1): V1 = 0.3mV * 101 + 0.2V = 0.23V Freescale Semiconductor, Inc... The voltage after the second gain stage comes from equation (2), V2 = 6 x 0.23V = 1.38 V. Therefore, before any pressure is applied to the sensor, a 1.38V DC signal will appear at V. Since the supply voltage is 3V, the available signal for actual pressure is 1.62 V. With a total gain of G1 x G2 = 606, the largest raw pressure signal that can be accurately measured would be 1.62V/606 = 2.67 mV. For the MPX2010 family operating at Vs = 3V, this corresponds to roughly 3.5 kPa. The board lends itself well to system integration via an A/D converter and microprocessor. For particular applications, general knowledge of the expected pressure signal can aid in choosing the proper customized gain. This will avoid op-amp saturation and will also ensure that the full-scale output signal is suitable for A/D conversion. To take another example, suppose that a particular application has the following constraints: Supply Voltage, Vs = 5.0 V, (thus VOFFSET = 6.7% x 5 = 0.335 V) Sensor zero-pressure offset voltage, VZP = 0.3mV Expected Pressure range = 0--2 kPa, (corresponds to DVSENSOR-MAX = 2.5mV @ 5V) Desired maximum output range, DV2MAX = 2V (assume VMIN = 2V, V2MAX = 4V for reasonable A/D resolution) By manipulating equations (1) and (2) it can be shown that, DV2MAX = GT x DVSENSOR-MAX where GT is the total gain, equal to G1G2. Thus GT = 2V/2.5mV = 800 To find G1 and G2, evaluate V2MIN at the zero pressure condition. V2MIN = G2 V1MIN, But V1MIN = G1 VZP + VOFFSET Thus V2MIN = GT VZP + G2 VOFFSET Solving for G2, G2 = (V2MIN - GT VZP)/ VOFFSET numerically, G2 = (2V -- (800x.0003V))/.335V G2 = 5.2, and G1 = GT /G2 = 152 Motorola Sensor Device Data AN4010 BOARD LAYOUT & CONTENT The low-pressure evaluation board has been designed using standard components. The only item that requires careful selection is the operation amplifier IC. Because the selected gain may be relatively high as in the previous example, it is essential that this device have a low offset voltage. A device with a typical voltage offset of 35 mV has been selected. Even with a gain of 1500, this will result in a 52mV offset. Table 3 is a parts list for the board layout shown in Figure1. 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Description Value Vendor Part No. X1 1 Pressure Sensor 10 Kpa Motorola MPX2010 MPXC2011 C1 1 Vcc Cap 1 uF Generic C2 1 Op-Amp Cap 0.1 uF Generic C3 1 2nd stage cap 4700 pF Generic D1 1 LED Generic for U1 1 Op-Amp socket Generic U1 1 Op-Amp Analog Devices R1, R4 2 1/4 W Resistor 100K Generic R2,R3, R5,R6 4 1/4 W Resistor 1K Generic R7 1 1/4 W Resistor 6.8K Generic R8 1 1/4 W Resistor 510 Generic R9 1 Potentiometer 1K Bourns R10 1 1/4 W Resistor 51K Generic R11 1 1/4 W Resistor custom Generic R12 1 1/4 W Resistor 2K Generic R41 1 1/4 W Resistor custom Generic R51 1 1/4 W Resistor custom Generic JP1 - JP7 7 Jumper Generic J1 1 3 Pos Connector Phoenix www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com OP496GP 3386P-102 MKDS1 3-421 AN4010 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Figure 6 illustrates the particular layout chosen for the evaluation board (LED and R12 are not shown). This layout can serve as a fully functional stand-alone board or can be the basis for integration into a system level layout. Through hole mounted components have been selected, and this dictates the particular footprint dimensions. However, with surface mount components, this layout can be made significantly smaller. EVALUATION NOTES: This board is designed to run from a regulated power source or from batteries. Since the pressure sensors are ratio-metric (meaning that the output scales with the applied supply voltage), supply voltages ranging from 3V to 10V can be used. The specified op-amp operates well within these values. In terms of sensor packages, four variations are recommended. They are the MPX2010D, MPX201DP, MPX2010GP and the MPXC2011DT1. Either of these sensors can be directly mounted on the board itself or can be remotely mounted and connected to it via wires. The customer can select the proper package depending on size requirements and on whether gauge, vacuum or differential pressure will be sensed. In particular, the MPXC2011DT1, known as the ChipPak sensor, is a very small package and can be used to sense differential and vacuum pressure provided that ports are attached on each side as shown in Figure 1. Note that Motorola does not provide these ports as standard products. Since the output signal of the evaluation board can be fined tuned to be a very measurable voltage, interfacing the board to an A/D, microprocessor, or other circuitry is very straightforward. CONCLUSION Component Side Figure 6a. Board Layout The low-pressure evaluation board provides design flexibility in terms of amplification, output type and packaging. Gains ranging from 50 up to 1500 can be easily implemented by simply soldering specific resistors and manipulating a few jumpers. Jumpers also control the type of output and allow the user to select analog or switching signals. Two sets of through hole sensor connections are provided for various pressure sensor packages, and customers are free to remotely mount the board via wires. In many applications, such as HVAC systems or medical respiratory equipment, quick and effective component evaluation is critical. The flexible features of this board allow a customer to reduce development time. Back Side Figure 6b. Board Layout 3-422 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Package Outline Dimensions C R M 1 B -A- 2 3 Z 4 DIM A B C D F G J L M N R Y Z N 1 PIN 1 2 3 L 4 -T- SEATING PLANE Freescale Semiconductor, Inc... J F G F D Y 4 PL 0.136 (0.005) T A M DAMBAR TRIM ZONE: THIS IS INCLUDED WITHIN DIM. "F" 8 PL M NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION -A- IS INCLUSIVE OF THE MOLD STOP RING. MOLD STOP RING NOT TO EXCEED 16.00 (0.630). INCHES MIN MAX 0.595 0.630 0.514 0.534 0.200 0.220 0.016 0.020 0.048 0.064 0.100 BSC 0.014 0.016 0.695 0.725 30 _ NOM 0.475 0.495 0.430 0.450 0.048 0.052 0.106 0.118 STYLE 1: PIN 1. 2. 3. 4. MILLIMETERS MIN MAX 15.11 16.00 13.06 13.56 5.08 5.59 0.41 0.51 1.22 1.63 2.54 BSC 0.36 0.40 17.65 18.42 30 _ NOM 12.07 12.57 10.92 11.43 1.22 1.32 2.68 3.00 GROUND + OUTPUT + SUPPLY - OUTPUT CASE 344-15 ISSUE AA SEATING PLANE NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5, 1982. 2. CONTROLLING DIMENSION: INCH. -A- -T- U L R H N PORT #1 POSITIVE PRESSURE (P1) -Q- B 1 2 3 4 PIN 1 K -P- 0.25 (0.010) J M T Q S S F C G D 4 PL 0.13 (0.005) M T S S Q S DIM A B C D F G H J K L N P Q R S U INCHES MIN MAX 1.145 1.175 0.685 0.715 0.305 0.325 0.016 0.020 0.048 0.064 0.100 BSC 0.182 0.194 0.014 0.016 0.695 0.725 0.290 0.300 0.420 0.440 0.153 0.159 0.153 0.159 0.230 0.250 0.220 0.240 0.910 BSC STYLE 1: PIN 1. 2. 3. 4. MILLIMETERS MIN MAX 29.08 29.85 17.40 18.16 7.75 8.26 0.41 0.51 1.22 1.63 2.54 BSC 4.62 4.93 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 5.84 6.35 5.59 6.10 23.11 BSC GROUND + OUTPUT + SUPPLY - OUTPUT CASE 344B-01 ISSUE B Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-423 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) PORT #1 R NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. -A- U V W L H PORT #2 N DIM A B C D F G H J K L N P Q R S U V W PORT #1 POSITIVE PRESSURE (P1) PORT #2 VACUUM (P2) -Q- B SEATING PLANE SEATING PLANE 1 2 3 4 PIN 1 K -P- -T- -T- 0.25 (0.010) M T Q S G D 4 PL C Freescale Semiconductor, Inc... S F J 0.13 (0.005) T S M S Q S INCHES MIN MAX 1.145 1.175 0.685 0.715 0.405 0.435 0.016 0.020 0.048 0.064 0.100 BSC 0.182 0.194 0.014 0.016 0.695 0.725 0.290 0.300 0.420 0.440 0.153 0.159 0.153 0.159 0.063 0.083 0.220 0.240 0.910 BSC 0.248 0.278 0.310 0.330 STYLE 1: PIN 1. 2. 3. 4. MILLIMETERS MIN MAX 29.08 29.85 17.40 18.16 10.29 11.05 0.41 0.51 1.22 1.63 2.54 BSC 4.62 4.93 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 1.60 2.11 5.59 6.10 23.11 BSC 6.30 7.06 7.87 8.38 GROUND + OUTPUT + SUPPLY - OUTPUT CASE 344C-01 ISSUE B NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5, 1982. 2. CONTROLLING DIMENSION: INCH. -A- U SEATING PLANE -T- L R DIM A B C D F G H J K L N P Q R S U H PORT #2 VACUUM (P2) POSITIVE PRESSURE (P1) N -Q- B 1 2 3 4 K PIN 1 S C J F -P- 0.25 (0.010) M T Q S G D 4 PL 0.13 (0.005) M T S S Q S INCHES MIN MAX 1.145 1.175 0.685 0.715 0.305 0.325 0.016 0.020 0.048 0.064 0.100 BSC 0.182 0.194 0.014 0.016 0.695 0.725 0.290 0.300 0.420 0.440 0.153 0.159 0.153 0.158 0.230 0.250 0.220 0.240 0.910 BSC STYLE 1: PIN 1. 2. 3. 4. MILLIMETERS MIN MAX 29.08 29.85 17.40 18.16 7.75 8.26 0.41 0.51 1.22 1.63 2.54 BSC 4.62 4.93 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 5.84 6.35 5.59 6.10 23.11 BSC GROUND + OUTPUT + SUPPLY - OUTPUT CASE 344D-01 ISSUE B 3-424 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) PORT #1 POSITIVE PRESSURE (P1) -B- C NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. A BACK SIDE VACUUM (P2) DIM A B C D F G J K N R S V V 4 3 2 1 PIN 1 K J N SEATING PLANE MILLIMETERS MIN MAX 17.53 18.28 6.22 6.48 19.81 20.82 0.41 0.51 1.22 1.63 2.54 BSC 0.36 0.41 8.76 9.53 7.62 7.87 4.52 4.72 5.59 6.10 4.62 4.93 G STYLE 1: PIN 1. 2. 3. 4. F R Freescale Semiconductor, Inc... S INCHES MIN MAX 0.690 0.720 0.245 0.255 0.780 0.820 0.016 0.020 0.048 0.064 0.100 BSC 0.014 0.016 0.345 0.375 0.300 0.310 0.178 0.186 0.220 0.240 0.182 0.194 D 4 PL 0.13 (0.005) -T- M T B M GROUND + OUTPUT + SUPPLY - OUTPUT CASE 344E-01 ISSUE B -T- C A E -Q- U N V B R PORT #1 POSITIVE PRESSURE (P1) PIN 1 -P- 0.25 (0.010) M T Q M 4 3 2 1 S K J F NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. DIM A B C D E F G J K N P Q R S U V INCHES MIN MAX 1.080 1.120 0.740 0.760 0.630 0.650 0.016 0.020 0.160 0.180 0.048 0.064 0.100 BSC 0.014 0.016 0.220 0.240 0.070 0.080 0.150 0.160 0.150 0.160 0.440 0.460 0.695 0.725 0.840 0.860 0.182 0.194 MILLIMETERS MIN MAX 27.43 28.45 18.80 19.30 16.00 16.51 0.41 0.51 4.06 4.57 1.22 1.63 2.54 BSC 0.36 0.41 5.59 6.10 1.78 2.03 3.81 4.06 3.81 4.06 11.18 11.68 17.65 18.42 21.34 21.84 4.62 4.92 G D 4 PL 0.13 (0.005) M T P S Q S STYLE 1: PIN 1. 2. 3. 4. GROUND V (+) OUT V SUPPLY V (-) OUT CASE 344F-01 ISSUE B Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-425 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) C A M L NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. F B N 1 2 3 4 V K -T- DETAIL A J H D1 G E END VIEW Freescale Semiconductor, Inc... FRONT VIEW DIM A B C D1 D2 E F G H J K L M N V AA AB AC AD INCHES MIN MAX 0.240 0.260 0.350 0.370 0.140 0.150 0.012 0.020 0.014 0.022 0.088 0.102 0.123 0.128 0.045 0.055 0.037 0.047 0.007 0.011 0.120 0.140 0.095 0.105 0.165 0.175 0.223 0.239 0.105 0.115 0.095 0.107 0.015 0.035 0.120 0.175 0.100 0.115 STYLE 1: PIN 1. 2. 3. 4. AC F MILLIMETERS MIN MAX 6.10 6.60 8.89 9.40 3.56 3.81 0.30 0.51 0.36 0.56 2.24 2.59 3.12 3.25 1.14 1.40 0.94 1.19 0.18 0.28 3.05 3.56 2.41 2.67 4.19 4.45 5.66 6.07 2.67 2.92 2.41 2.72 0.38 0.89 3.05 4.45 2.54 2.92 VCC +OUT -OUT GROUND AA AB D2 AD DETAIL A BACK VIEW CASE 423A-03 ISSUE C 3-426 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) -A- D 8 PL 4 0.25 (0.010) 5 M T B A S NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006). 5. ALL VERTICAL SURFACES 5_ TYPICAL DRAFT. S -B- G 8 1 S N Freescale Semiconductor, Inc... H C J -T- PIN 1 IDENTIFIER M K SEATING PLANE DIM A B C D G H J K M N S INCHES MIN MAX 0.415 0.425 0.415 0.425 0.212 0.230 0.038 0.042 0.100 BSC 0.002 0.010 0.009 0.011 0.061 0.071 0_ 7_ 0.405 0.415 0.709 0.725 MILLIMETERS MIN MAX 10.54 10.79 10.54 10.79 5.38 5.84 0.96 1.07 2.54 BSC 0.05 0.25 0.23 0.28 1.55 1.80 0_ 7_ 10.29 10.54 18.01 18.41 CASE 482-01 ISSUE O -A- D 8 PL 4 0.25 (0.010) 5 M T B S A NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006). 5. ALL VERTICAL SURFACES 5_ TYPICAL DRAFT. S N -B- G 8 1 S DIM A B C D G H J K M N S V W W V C H J INCHES MIN MAX 0.415 0.425 0.415 0.425 0.500 0.520 0.038 0.042 0.100 BSC 0.002 0.010 0.009 0.011 0.061 0.071 0_ 7_ 0.444 0.448 0.709 0.725 0.245 0.255 0.115 0.125 MILLIMETERS MIN MAX 10.54 10.79 10.54 10.79 12.70 13.21 0.96 1.07 2.54 BSC 0.05 0.25 0.23 0.28 1.55 1.80 0_ 7_ 11.28 11.38 18.01 18.41 6.22 6.48 2.92 3.17 -T- K M PIN 1 IDENTIFIER SEATING PLANE CASE 482A-01 ISSUE A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-427 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) -A- NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006). 5. ALL VERTICAL SURFACES 5_ TYPICAL DRAFT. 6. DIMENSION S TO CENTER OF LEAD WHEN FORMED PARALLEL. 4 5 -B- G 8 1 0.25 (0.010) M T B D 8 PL S A DETAIL X S PIN 1 IDENTIFIER N Freescale Semiconductor, Inc... S C -T- SEATING PLANE DIM A B C D G J K M N S INCHES MIN MAX 0.415 0.425 0.415 0.425 0.210 0.220 0.026 0.034 0.100 BSC 0.009 0.011 0.100 0.120 0_ 15 _ 0.405 0.415 0.540 0.560 MILLIMETERS MIN MAX 10.54 10.79 10.54 10.79 5.33 5.59 0.66 0.864 2.54 BSC 0.23 0.28 2.54 3.05 0_ 15 _ 10.29 10.54 13.72 14.22 K M J DETAIL X CASE 482B-03 ISSUE B NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006). 5. ALL VERTICAL SURFACES 5_ TYPICAL DRAFT. 6. DIMENSION S TO CENTER OF LEAD WHEN FORMED PARALLEL. -A- 4 5 N -B- G 0.25 (0.010) 8 1 M T B D 8 PL S A S DIM A B C D G J K M N S V W DETAIL X S W V PIN 1 IDENTIFIER C -T- INCHES MIN MAX 0.415 0.425 0.415 0.425 0.500 0.520 0.026 0.034 0.100 BSC 0.009 0.011 0.100 0.120 0_ 15 _ 0.444 0.448 0.540 0.560 0.245 0.255 0.115 0.125 MILLIMETERS MIN MAX 10.54 10.79 10.54 10.79 12.70 13.21 0.66 0.864 2.54 BSC 0.23 0.28 2.54 3.05 0_ 15 _ 11.28 11.38 13.72 14.22 6.22 6.48 2.92 3.17 SEATING PLANE K M J DETAIL X CASE 482C-03 ISSUE B 3-428 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) C NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION -A- IS INCLUSIVE OF THE MOLD STOP RING. MOLD STOP RING NOT TO EXCEED 16.00 (0.630). R POSITIVE PRESSURE (P1) M B -A- N PIN 1 SEATING PLANE 1 2 3 4 5 DIM A B C D F G J L M N R S L 6 -T- G J S F D 6 PL Freescale Semiconductor, Inc... 0.136 (0.005) M T A M INCHES MIN MAX 0.595 0.630 0.514 0.534 0.200 0.220 0.027 0.033 0.048 0.064 0.100 BSC 0.014 0.016 0.695 0.725 30 _NOM 0.475 0.495 0.430 0.450 0.090 0.105 STYLE 1: PIN 1. 2. 3. 4. 5. 6. CASE 867-08 ISSUE N MILLIMETERS MIN MAX 15.11 16.00 13.06 13.56 5.08 5.59 0.68 0.84 1.22 1.63 2.54 BSC 0.36 0.40 17.65 18.42 30 _NOM 12.07 12.57 10.92 11.43 2.29 2.66 VOUT GROUND VCC V1 V2 VEX BASIC ELEMENT (A, D) T NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. A U L SEATING PLANE R V DIM A B C D F G J K L N P Q R S U V Q N Q B 1 6 2 3 4 5 K P PIN 1 P C J 0.25 M T Q S G M 6X F D 0.173 M T P S Q S CASE 867B-04 ISSUE F MILLIMETERS MIN MAX 29.08 29.85 17.4 18.16 7.75 8.26 0.68 0.84 1.22 1.63 2.54 BSC 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 5.84 6.35 5.59 6.1 23.11 BSC 4.62 4.93 STYLE 1: PIN 1. 2. 3. 4. 5. 6. VOUT GROUND VCC V1 V2 VEX PRESSURE SIDE PORTED (AP, GP) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-429 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) P 0.25 (0.010) M T Q -A- M U W X R PORT #1 POSITIVE PRESSURE (P1) NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. L V PORT #2 VACUUM (P2) PORT #1 POSITIVE PRESSURE (P1) N -Q- PORT #2 VACUUM (P2) B PIN 1 1 2 3 4 5 K 6 Freescale Semiconductor, Inc... C SEATING PLANE -T- -T- S SEATING PLANE D 6 PL G J F 0.13 (0.005) M A DIM A B C D F G J K L N P Q R S U V W X INCHES MIN MAX 1.145 1.175 0.685 0.715 0.405 0.435 0.027 0.033 0.048 0.064 0.100 BSC 0.014 0.016 0.695 0.725 0.290 0.300 0.420 0.440 0.153 0.159 0.153 0.159 0.063 0.083 0.220 0.240 0.910 BSC 0.182 0.194 0.310 0.330 0.248 0.278 STYLE 1: PIN 1. 2. 3. 4. 5. 6. M CASE 867C-05 ISSUE F MILLIMETERS MIN MAX 29.08 29.85 17.40 18.16 10.29 11.05 0.68 0.84 1.22 1.63 2.54 BSC 0.36 0.41 17.65 18.42 7.37 7.62 10.67 11.18 3.89 4.04 3.89 4.04 1.60 2.11 5.59 6.10 23.11 BSC 4.62 4.93 7.87 8.38 6.30 7.06 VOUT GROUND VCC V1 V2 VEX PRESSURE AND VACUUM SIDES PORTED (DP) C -B- NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. A DIM A B C D E F G J K N S V V PIN 1 PORT #1 POSITIVE PRESSURE (P1) 6 K J N 5 -T- 3 2 1 S G F E 4 D 6 PL 0.13 (0.005) M T B M INCHES MIN MAX 0.690 0.720 0.245 0.255 0.780 0.820 0.027 0.033 0.178 0.186 0.048 0.064 0.100 BSC 0.014 0.016 0.345 0.375 0.300 0.310 0.220 0.240 0.182 0.194 STYLE 1: PIN 1. 2. 3. 4. 5. 6. MILLIMETERS MIN MAX 17.53 18.28 6.22 6.48 19.81 20.82 0.69 0.84 4.52 4.72 1.22 1.63 2.54 BSC 0.36 0.41 8.76 9.53 7.62 7.87 5.59 6.10 4.62 4.93 VOUT GROUND VCC V1 V2 VEX CASE 867E-03 ISSUE D PRESSURE SIDE PORTED (AS, GS) 3-430 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) -T- C A U E -Q- N V B R PIN 1 PORT #1 POSITIVE PRESSURE (P1) -P- 0.25 (0.010) M T Q 6 M 5 4 3 2 1 S Freescale Semiconductor, Inc... K J 0.13 (0.005) M T P S D 6 PL Q S G F NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. DIM A B C D E F G J K N P Q R S U V INCHES MIN MAX 1.080 1.120 0.740 0.760 0.630 0.650 0.027 0.033 0.160 0.180 0.048 0.064 0.100 BSC 0.014 0.016 0.220 0.240 0.070 0.080 0.150 0.160 0.150 0.160 0.440 0.460 0.695 0.725 0.840 0.860 0.182 0.194 STYLE 1: PIN 1. 2. 3. 4. 5. 6. MILLIMETERS MIN MAX 27.43 28.45 18.80 19.30 16.00 16.51 0.68 0.84 4.06 4.57 1.22 1.63 2.54 BSC 0.36 0.41 5.59 6.10 1.78 2.03 3.81 4.06 3.81 4.06 11.18 11.68 17.65 18.42 21.34 21.84 4.62 4.93 VOUT GROUND VCC V1 V2 VEX CASE 867F-03 ISSUE D PRESSURE SIDE PORTED (ASX, GSX) Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-431 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2X 0.006 C A B 0.420 0.400 0.050 0.025 0.300 0.280 3 NOTES: 1. ALL DIMENSIONS ARE IN INCHES. 2. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994. 3. DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006 INCHES PER SIDE. 4. ALL VERTICAL SURFACES TO BE 5 MAXIMUM. 5. DIMENSION DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE .008 INCHES MAXIMUM. 0.019 5 0.014 0.004 M C A B 8X Freescale Semiconductor, Inc... A 0.300 0.280 B 3 0.298 0.278 .010 GAGE PLANE 0.165 0.145 0.010 0.002 0.004 DETAIL E C 0.023 0.013 10 0 DETAIL E SEATING PLANE CASE 1317-03 ISSUE B 3-432 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2X 0.006 C A B 0.420 0.400 NOTES: 1. ALL DIMENSIONS ARE IN INCHES. 2. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994. 3. DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006 INCHES PER SIDE. 4. ALL VERTICAL SURFACES TO BE 5 MAXIMUM. 5. DIMENSION DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE .008 INCHES MAXIMUM. 0.050 0.025 0.345 0.325 Freescale Semiconductor, Inc... 8X A 0.345 0.325 B 0.018 0.014 0.004 M 5 .014 C A B GAGE PLANE 0.010 0.002 0.048 0.038 0.130 0.110 10 0 DETAIL E 0.200 0.180 0.300 0.280 0.390 0.370 3 0.004 A DETAIL E C 0.300 0.280 B 3 SEATING PLANE BOTTOM VIEW CASE 1317A-01 ISSUE A Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-433 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2X NOTES: 1. DIMENSIONS ARE IN INCHES. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD FLASH OR PROTRUSION. MOLD FLASH OR PROTRUSION SHALL NOT EXCEED .006" PER SIDE. 4. ALL VERTICAL SURFACES TO BE 5 MAXIMUM. 5. DIMENSIONS "b" DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE .008 MAXIMUM. 0.006 C A B E e PIN 4 e/2 PIN 1 b1 4X 0.004 M C A B 0.004 E1 Freescale Semiconductor, Inc... DIM A A1 b b1 D E E1 e e/2 L B M b C A B A D STYLE 1: PIN 1. 2. 3. 4. INCHES MIN MAX .155 .165 .002 .010 .014 .018 .120 .130 .245 .255 .475 .485 .325 .335 .050 BSC .025 BSC .038 .048 0 7 GND +Vout Vs -Vout A .014 0.004 GAGE PLANE DETAIL E C SEATING PLANE A1 L CASE 1320-02 ISSUE A 3-434 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com DETAIL E Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2X 0.006 C A B E .014 e GAGE PLANE e/2 A1 L DETAIL E 4X 0.004 Freescale Semiconductor, Inc... 0.004 N b1 M NOTES: 1. DIMENSIONS ARE IN INCHES. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD FLASH OR PROTRUSION. MOLD FLASH OR PROTRUSION SHALL NOT EXCEED .006" PER SIDE. 4. ALL VERTICAL SURFACES TO BE 5 MAXIMUM. 5. DIMENSIONS "b" DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE .008 MAXIMUM. b C A B M C A B P S A DETAIL E 0.004 E1 C B A D DIM A A1 b b1 D E E1 e e/2 L M N P S INCHES MIN MAX .377 .397 .002 .010 .014 .018 .120 .130 .245 .255 .475 .485 .325 .335 .050 BSC .025 BSC .013 .023 .283 .293 .363 .373 .107 .117 .192 .202 0 7 SEATING PLANE CASE 1320A-02 ISSUE O Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-435 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2 PLACES 4 TIPS 0.006 (0.15) C A B E A GAGE PLANE e 5 4 e/2 .014 (0.35) L D A1 DETAIL G 8 1 b 0.004 (0.1) 8X Freescale Semiconductor, Inc... F M C A B E1 B N GND +Vout Vs -Vout N/C N/C N/C N/C T M A P STYLE 1: PIN 1. 2. 3. 4. 5. 6. 7. 8. 8X 0.004 (0.1) DETAIL G C K SEATING PLANE STYLE 2: PIN 1. 2. 3. 4. 5. 6. 7. 8. N/C Vs GND Vout N/C N/C N/C N/C NOTES: 1. CONTROLLING DIMENSION: INCH. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 (0.152) PER SIDE. 4. DIMENSION "b" DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.008 (0.203) MAXIMUM. DIM A A1 b D E E1 e F K L M N P T INCHES MIN MAX 0.370 0.390 0.002 0.010 0.038 0.042 0.465 0.485 0.680 0.700 0.465 0.485 0.100 BSC 0.240 0.260 0.115 0.135 0.040 0.060 0.270 0.290 0.160 0.180 0.009 0.011 0.110 0.130 0 7 MILLIMETERS MIN MAX 9.39 9.91 0.05 0.25 0.96 1.07 11.81 12.32 17.27 17.78 11.81 12.32 2.54 BSC 6.10 6.60 2.92 3.43 1.02 1.52 6.86 7.37 4.06 4.57 0.23 0.28 2.79 3.30 0 7 CASE 1351-01 ISSUE O 3-436 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2 PLACES 4 TIPS 0.006 (0.15) C A B E A GAGE PLANE e 5 4 e/2 .014 (0.35) L D A1 DETAIL G 8 1 b 0.004 (0.1) 8X Freescale Semiconductor, Inc... F M E1 B N C A B STYLE 1: PIN 1. 2. 3. 4. 5. 6. 7. 8. GND +Vout Vs -Vout N/C N/C N/C N/C STYLE 2: PIN 1. 2. 3. 4. 5. 6. 7. 8. N/C Vs GND Vout N/C N/C N/C N/C NOTES: 1. CONTROLLING DIMENSION: INCH. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 (0.152) PER SIDE. 4. DIMENSION "b" DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.008 (0.203) MAXIMUM. R T K A P 8X 0.004 (0.1) M DETAIL G C SEATING PLANE DIM A A1 b D E E1 e F K L M N P T R INCHES MIN MAX 0.280 0.300 0.002 0.010 0.038 0.042 0.465 0.485 0.690 BSC 0.465 0.485 0.100 BSC 0.240 0.260 0.115 0.135 0.040 0.060 0.035 0.055 0.075 0.095 0.009 0.011 0.110 0.130 0.405 0.415 0 7 MILLIMETERS MIN MAX 7.11 7.62 0.05 0.25 0.96 1.07 11.81 12.32 17.52 BSC 11.81 12.32 2.54 BSC 6.10 6.60 2.92 3.43 1.02 1.52 1.90 2.41 0.89 1.39 0.23 0.28 2.79 3.30 10.28 10.54 0 7 CASE 1368-01 ISSUE O Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-437 Freescale Semiconductor, Inc. PACKAGE OUTLINE DIMENSIONS (continued) 2 PLACES 4 TIPS 0.008 (0.20) C A B E A e 5 GAGE PLANE 4 e/2 .014 (0.35) D L A1 DETAIL G 8 NOTES: 1. CONTROLLING DIMENSION: INCH. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M-1994. 3. DIMENSIONS "D" AND "E1" DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 (0.152) PER SIDE. 4. DIMENSION "b" DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.008 (0.203) MAXIMUM. 1 b 0.004 (0.1) 8X Freescale Semiconductor, Inc... F C A B E1 B N T K A P M 8X M 0.004 (0.1) DETAIL G C SEATING PLANE DIM A A1 b D E E1 e F K L M N P T INCHES MIN MAX 0.300 0.330 0.002 0.010 0.038 0.042 0.465 0.485 0.717 BSC 0.465 0.485 0.100 BSC 0.245 0.255 0.120 0.130 0.061 0.071 0.270 0.290 0.080 0.090 0.009 0.011 0.115 0.125 0 7 MILLIMETERS MIN MAX 7.11 7.62 0.05 0.25 0.96 1.07 11.81 12.32 18.21 BSC 11.81 12.32 2.54 BSC 6.22 6.47 3.05 3.30 1.55 1.80 6.86 7.36 2.03 2.28 0.23 0.28 2.92 3.17 0 7 CASE 1369-01 ISSUE O 3-438 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Reference Tables FLOW EQUIVALENTS 1 Cu. Ft./Hr. 0.0166 0.4719 28.316 471.947 28317 0.1247 7.481 1 Cu. Ft./Min. 60 28.316 1699 28317 1,699,011 7.481 448.831 Cu. Ft./Min LPM LPH CC/Min. CC/Hr. Gal/Min. Gal/Hr. Freescale Semiconductor, Inc... 1 LPM 60 0.035 2.1189 1000 60,002 0.264 15.851 Cu. Ft./Min LPM LPH CC/Min. CC/Hr. Gal/Min. Gal/Hr. 1 CC/Min. 1 LPH 0.0166 0.00059 0.035 16.667 1000 0.004 0.264 LPH Cu. Ft./Min. Cu. Ft./Hr. CC/Min. CC/Hr. Gal/Min. Gal/Hr. LPM Cu. Ft./Min. Cu. Ft./Hr. CC/Min. CC/Hr. Gal/Min. Gal/Hr. Knots 860 880 100 110 120 130 140 150 175 200 225 250 275 300 325 350 375 0.1727 0.3075 0.4814 0.5832 0.6950 0.8168 0.9488 1.0910 1.4918 1.9589 2.4943 3.1002 3.7792 4.5343 5.3687 6.2859 7.2900 Knots Inches of Mercury 8,400 8,425 8,450 8,475 8,500 8,525 8,550 8,575 8,600 8,650 8,700 8,750 8,800 8,850 8,900 1,000 88.3850 89.5758 10.8675 12.2654 13.7756 15.4045 17.1590 19.0465 21.0749 25.5893 30.7642 36.5662 42.9378 49.8423 57.2554 73.5454 Motorola Sensor Device Data 1 CC/Hr. 0.0167 0.0000005 0.00003 0.000017 0.001 0.000004 0.00026 1 Gal/Min. 60 0.1337 8.021 3.785 227.118 3,785.412 227,125 Airspeed Inches of Mercury CC/Hr. Cu. Ft./Min Cu. Ft./Hr. LPM LPH Gal/Min. Gal/Hr. 60 0.000035 0.0021 0.001 0.06 0.00026 0.0159 Altitude (Feet) Equivalent Pressure (inches of Mercury) -1,000 -900 0 500 1,000 1,500 2,000 3,000 4,000 6,000 8,000 10,000 12,000 31.0185 30.9073 29.9213 29.3846 28.8557 28.3345 27.8210 26.8167 25.8418 23.9782 22.2250 20.5770 19.0294 Gal/Hr. Cu. Ft./Min. Cu. Ft./Hr. LPM LPH CC/Min. CC/Hr. 1 Gal/Hr. 0.0167 0.002 0.1337 0.063 3.785 63.069 3785 Altitude (Feet) Equivalent Pressure (inches of Mercury) 14,000 16,000 18,000 20,000 22,000 25,000 30,000 35,000 40,000 45,000 49,900 50,000 17.5774 16.2164 14.9421 13.7501 12.6363 11.1035 8.88544 7.04062 5.53802 4.35488 3.44112 (EST) 3.42466 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com CC/Min. Cu. Ft./Min. Cu. Ft./Hr. LPM LPH Gal/Min. Gal/Hr. Gal/Min. Cu. Ft./Min. Cu. Ft./Hr. LPM LPH CC/Min. CC/Hr. 3-439 Freescale Semiconductor, Inc. Reference Tables (continued) Conversion Table for Common Units of Pressure Freescale Semiconductor, Inc... kiloPascals mm Hg millibars inches H2O PSI 1 atm 101.325 760.000 1013.25 406.795 14.6960 1 kiloPascal 1.00000 7.50062 10.0000 4.01475 0.145038 1 mm Hg 0.133322 1.00000 1.33322 0.535257 0.0193368 1 millibar 0.100000 0.750062 1.00000 0.401475 0.0145038 1 inch H2O 0.249081 1.86826 2.49081 1.00000 0.0361 1 PSI 6.89473 51.7148 68.9473 27.6807 1.00000 1 hectoPascal 0.100000 0.75006 1.00000 0.401475 0.0145038 1 cm H2O 0.09806 0.7355 9.8 x 10-7 0.3937 0.014223 Quick Conversion Chart for Common Units of Pressure kiloPascals 0 20 40 60 80 100 120 140 160 180 200 inches H2O 0 100 200 300 400 500 600 700 800 millibars 0 200 400 600 800 1000 1200 1400 1600 1800 2000 mm Hg 0 200 400 600 800 1000 1200 1400 1600 PSI 0 3-440 5 10 15 20 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 25 30 Motorola Sensor Device Data Freescale Semiconductor, Inc. Mounting and Handling Suggestions .114 .047 TOP CLAMP AREA 0 .125 .075 .037R 0 .210 Freescale Semiconductor, Inc... CELL .021 Figure 1. BOTTOM CLAMP AREA Leads should be securely clamped top and bottom in the area between the plastic body and the form being sure that no stress is being put on plastic body. The area between dotted lines represents surfaces to be clamped. Figure 3. Leadforming Custom Port Adaptor Installation Techniques Standard Port Attach Connection The Motorola MPX silicon pressure sensor is available in a basic chip carrier cell which is adaptable for attachment to customer specific housings/ports (Case 344 for 4-pin devices and Case 867 for 6-pin devices). The basic cell has chamfered shoulders on both sides which will accept an Oring such as Parker Seal's silicone O-ring (p/n#2-015-S-469-40). Refer to Figure 1 for the recommended O-ring to sensor cell interface dimensions. The sensor cell may also be glued directly to a custom housing or port using many commercial grade epoxies or RTV adhesives which adhere to grade Valox 420, reinforced polyester resin plastic polysulfone (MPX2040D only). The epoxy should be dispensed in a continuous bead around the cell-to-port interface shoulder. Refer to Figure 2. Care must be taken to avoid gaps or voids in the adhesive bead to help ensure that a complete seal is made when the cell is joined to the port. After cure, a simple test for gross leaks should be performed to ensure the integrity of the cell to port bond. Submerging the device in water for 5 seconds with full rated pressure applied to the port nozzle and checking for air bubbles will provide a good indication. Be sure device is thoroughly dried after this test. Motorola also offers standard port options designed to accept readily available silicone, vinyl, nylon or polyethylene tubing for the pressure connection. The inside dimension of the tubing selected should provide a snug fit over the port nozzle. Dimensions of the ports may be found in the case outline drawings. Installation and removal of tubing from the port nozzle must be parallel to the nozzle to avoid undue stress which may break the nozzle from the port base. Whether sensors are used with Motorola's standard ports or customer specific housings, care must be taken to ensure that force is uniformly distributed to the package or offset errors may be induced. ADHESIVE BEAD Figure 2. Motorola Sensor Device Data Electrical Connection The MPX series pressure sensor is designed to be installed on a printed circuit board (standard 0.100 lead spacing) or to accept an appropriate connector if installed on a baseplate. The leads of the sensor may be formed at right angles for assembly to the circuit board, but one must ensure that proper leadform techniques and tools are employed. Hand or "needlenose" pliers should never be used for leadforming unless they are specifically designed for that purpose. Industrial leadform tooling is available from various companies including Janesville Tool & Manufacturing (608-868-4925). Refer to Figure 3 for the recommended leadform technique. It is also important that once the leads are formed, they should not be straightened and reformed without expecting reduced durability. The recommended connector for off-circuit board applications may be supplied by JST Corp. (1-800-292-4243) in Mount Prospect, IL. The part numbers for the housing and pins are: 4 Pin Housing: SMP-04V-BC 6 Pin Housing: SMP-06V-BC Pin: SHF-01T-0.8SS The crimp tool part number is: YC12. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-441 Freescale Semiconductor, Inc. Standard Warranty Clause Seller warrants that its products sold hereunder will at the time of shipment be free from defects in material and workmanship, and will conform to Seller's approved specifications. If products are not as warranted, Seller shall, at its option and as Buyer's exclusive remedy, either refund the purchase price, or repair, or replace the product, provided proof of purchase and written notice of nonconformance are received within the applicable periods noted below and provided said nonconforming products are, with Seller's written authorization, returned in protected shipping containers FOB Seller's plant within thirty (30) days after expiration of the warranty period unless otherwise specified herein. If product does not conform to this warranty, Seller will pay for the reasonable cost of transporting the goods to and from Seller's plant. This warranty shall not apply to any products Seller determines have been, by Buyer or otherwise, subjected to improper testing, or have been the subject of mishandling or misuse. Freescale Semiconductor, Inc... THIS WARRANTY EXTENDS TO BUYER ONLY AND MAY BE INVOKED BY BUYER ONLY FOR ITS CUSTOMERS. SELLER WILL NOT ACCEPT WARRANTY RETURNS DIRECTLY FROM BUYER'S CUSTOMERS OR USERS OF BUYER'S PRODUCTS. THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES WHETHER EXPRESS, IMPLIED OR STATUTORY INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Seller's warranty shall not be enlarged, and no obligation or liability shall arise out of Seller's rendering of technical advice and/or assistance. A. Time periods, products, exceptions and other restrictions applicable to the above warranty are: (1) Unless otherwise stated herein, products are warranted for a period of one (1) year from date of shipment. (2) Device Chips/Wafers. Seller warrants that device chips or wafers have, at shipment, been subjected to electrical test/probe and visual inspection. Warranty shall apply to products returned to Seller within ninety (90) days from date of shipment. This warranty shall not apply to any chips or wafers improperly removed from their original shipping container and/or subjected to testing or operational procedures not approved by Seller in writing. B. Development products and Licensed Programs are licensed on an "AS IS" basis. IN NO EVENT SHALL SELLER BE LIABLE FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES. 3-442 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Glossary of Terms Absolute Pressure Sensor A sensor which measures input pressure in relation to a zero pressure (a total vacuum on one side of the diaphragm) reference. Analog Output An electrical output from a sensor that changes proportionately with any change in input pressure. Accuracy -- also see Pressure Error A comparison of the actual output signal of a device to the true value of the input pressure. The various errors (such as linearity, hysteresis, repeatability and temperature shift) attributing to the accuracy of a device are usually expressed as a percent of full scale output (FSO). Altimetric Pressure Transducer A barometric pressure transducer used to determine altitude from the pressure-altitude profile. Barometric Pressure Transducer An absolute pressure sensor that measures the local ambient atmospheric pressure. Burst Pressure The maximum pressure that can be applied to a transducer without rupture of either the sensing element or transducer case. Calibration A process of modifying sensor output to improve output accuracy. Chip A die (unpackaged semiconductor device) cut from a silicon wafer, incorporating semiconductor circuit elements such as resistors, diodes, transistors, and/or capacitors. Compensation Added circuitry or materials designed to counteract known sources of error. Diaphragm The membrane of material that remains after etching a cavity into the silicon sensing chip. Changes in input pressure cause the diaphragm to deflect. Differential Pressure Sensor A sensor which is designed to accept simultaneously two independent pressure sources. The output is proportional to the pressure difference between the two sources. Diffusion A thermochemical process whereby controlled impurities are introduced into the silicon to define the piezoresistor. Compared to ion implantation, it has two major disadvantages: 1) the maximum impurity concentration occurs at the surface of the silicon rendering it subject to surface contamination, and making it nearly impossible to produce buried piezoresistors; 2) control over impurity concentrations and levels is about one thousand times poorer than obtained with ion implantation. Drift An undesired change in output over a period of time, with constant input pressure applied. End Point Straight Line Fit Motorola's method of defining linearity. The maximum deviation of any data point on a sensor output curve from a straight line drawn between the end data points on that output curve. Error The algebraic difference between the indicated value and the true value of the input pressure. Usually expressed in percent of full scale span, sometimes expressed in percent of the sensor output reading. Error Band The band of maximum deviations of the output values from a specified reference line or curve due to those causes attributable to the sensor. Usually expressed as " % of full scale output." The error band should be specified as applicable over at least two calibration cycles, so as to include repeatability, and verified accordingly. Excitation Voltage (Current) -- see Supply Voltage (Current) The external electrical voltage and/or current applied to a sensor for its proper operation (often referred to as the supply circuit or voltage). Motorola specifies constant voltage operation only. Full Scale Output The output at full scale pressure at a specified supply voltage. This signal is the sum of the offset signal plus the full scale span. Full Scale Span The change in output over the operating pressure range at a specified supply voltage. The SPAN of a device is the output voltage variation given between zero differential pressure and any given pressure. FULL SCALE SPAN is the output variation between zero differential pressure and when the maximum recommended operating pressure is applied. Hysteresis -- also see Pressure Hysteresis and Temperature Hysteresis HYSTERESIS refers to a transducer's ability to reproduce the same output for the same input, regardless of whether the input is increasing or decreasing. PRESSURE HYSTERESIS is measured at a constant temperature while TEMPERATURE HYSTERESIS is measured at a constant pressure in the operating pressure range. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-443 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Glossary of Terms (continued) Input Impedance (Resistance) The impedance (resistance) measured between the positive and negative (ground) input terminals at a specified frequency with the output terminals open. For Motorola X-ducer, this is a resistance measurement only. Ion Implantation A process whereby impurity ions are accelerated to a specific energy level and impinged upon the silicon wafer. The energy level determines the depth to which the impurity ions penetrate the silicon. Impingement time determines the impurity concentration. Thus, it is possible to independently control these parameters, and buried piezoresistors are easily produced. Ion implantation is increasingly used throughout the semiconductor industry to provide a variety of products with improved performance over those produced by diffusion. Laser Trimming (Automated) A method for adjusting the value of thin film resistors using a computer-controlled laser system. Leakage Rate The rate at which a fluid is permitted or determined to leak through a seal. The type of fluid, the differential pressure across the seal, the direction of leakage, and the location of the seal must be specified. Linearity Error The maximum deviation of the output from a straight line relationship with pressure over the operating pressure range, the type of straight line relationship (end point, least square approximation, etc.) should be specified. Load Impedance The impedance presented to the output terminals of a sensor by the associated external circuitry. Null The condition when the pressure on each side of the sensing diaphragm is equal. Null Offset The electrical output present, when the pressure sensor is at null. Null Temperature Shift The change in null output value due to a change in temperature. Null Output See ZERO PRESSURE OFFSET Offset See ZERO PRESSURE OFFSET Operating Pressure Range The range of pressures between minimum and maximum pressures at which the output will meet the specified operating characteristics. Operating Temperature Range The range of temperature between minimum and maximum temperature at which the output will meet the specified operating characteristics. Output Impedance The impedance measured between the positive and negative (ground) output terminals at a specified frequency with the input open. Overpressure The maximum specified pressure which may be applied to the sensing element of a sensor without causing a permanent change in the output characteristics. Piezoresistance A resistive element that changes resistance relative to the applied stress it experiences (e.g., strain gauge). Pressure Error The maximum difference between the true pressure and the pressure inferred from the output for any pressure in the operating pressure range. Pressure Hysteresis The difference in the output at any given pressure in the operating pressure range when this pressure is approached from the minimum operating pressure and when approached from the maximum operating pressure at room temperature. Pressure Range -- also see Operating Pressure Range The pressure limits over which the pressure sensor is calibrated or specified. Pressure Sensor A device that converts an input pressure into an electrical output. Proof Pressure See OVERPRESSURE Ratiometric Ratiometricity refers to the ability of the transducer to maintain a constant sensitivity, at a constant pressure, over a range of supply voltage values. Ratiometric (Ratiometricity Error) At a given supply voltage, sensor output is a proportion of that supply voltage. Ratiometricity error is the change in this proportion resulting from any change to the supply voltage. Usually expressed as a percent of full scale output. 3-444 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Glossary of Terms (continued) Range See OPERATING PRESSURE RANGE Repeatability The maximum change in output under fixed operating conditions over a specified period of time. Resolution The maximum change in pressure required to give a specified change in the output. Response Time The time required for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. Room Conditions Ambient environmental conditions under which sensors most commonly operate. Sensing Element That part of a sensor which responds directly to changes in input pressure. Sensitivity The change in output per unit change in pressure for a specified supply voltage or current. Sensitivity Shift A change in sensitivity resulting from an environmental change such as temperature. Stability The maximum difference in the output at any pressure in the operating pressure range when this pressure is applied consecutively under the same conditions and from the same direction. Storage Temperature Range The range of temperature between minimum and maximum which can be applied without causing the sensor to fail to meet the specified operating characteristics. Strain Gauge A sensing device providing a change in electrical resistance proportional to the level of applied stress. Supply Voltage (Current) The voltage (current) applied to the positive and negative (ground) input terminals. Temperature Coefficient of Full Scale Span The percent change in full scale span per unit change in temperature relative to the full scale span at a specified temperature. Temperature Coefficient of Resistance The percent change in the DC input impedance per unit change in temperature relative to the DC input impedance at a specified temperature. Temperature Error The maximum change in output at any pressure in the operating pressure range when the temperature is changed over a specified temperature range. Temperature Hysteresis The difference in output at any temperature in the operating temperature range when the temperature is approached from the minimum operating temperature and when approached from the maximum operating temperature with zero pressure applied. Thermal Offset Shift See TEMPERATURE COEFFICIENT OF OFFSET Thermal Span Shift See TEMPERATURE COEFFICIENT OF FULL SCALE SPAN Thermal Zero Shift See TEMPERATURE COEFFICIENT OF OFFSET Thin Film A technology using vacuum deposition of conductors and dielectric materials onto a substrate (frequently silicon) to form an electrical circuit. Vacuum A perfect vacuum is the absence of gaseous fluid. Zero Pressure Offset The output at zero pressure (absolute or differential, depending on the device type) for a specified supply voltage or current. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 3-445 Freescale Semiconductor, Inc. Symbols, Terms and Definitions Freescale Semiconductor, Inc... The following are the most commonly used letter symbols, terms and definitions associated with solid state silicon pressure sensors. Pburst Burst Pressure The maximum pressure that can be applied to a transducer without rupture of either the sensing element or transducer case. Io supply current The current drawn by the sensor from the voltage source. Io+ output source current The current sourcing capability of the pressure sensor. kPa kilopascals Unit of pressure. 1 kPa = 0.145038 PSI. -- Linearity The maximum deviation of the output from a straight line relationship with pressure over the operating pressure range, the type of straight line relationship (end point, least square approximation, etc.) should be specified. mm Hg millimeters of mercury Unit of pressure. 1 mmHg = 0.0193368 PSI. Pmax overpressure The maximum specified pressure which may be applied to the sensing element without causing a permanent change in the output characteristics. POP operating pressure range The range of pressures between minimum and maximum temperature at which the output will meet the specified operating characteristics. -- Pressure Hysteresis The difference in the output at any given pressure in the operating pressure range when this pressure is approached from the minimum operating pressure and when approached from the maximum operating pressure at room temperature. PSI pounds per square inch Unit of pressure. 1 PSI = 6.89473 kPa. -- Repeatability The maximum change in output under fixed operating conditions over a specified period of time. Ro input resistance The resistance measured between the positive and negative input terminals at a specified frequency with the output terminals open. TA operating temperature The temperature range over which the device may safely operate. TCR temperature coefficient of resistance The percent change in the DC input impedance per unit change in temperature relative to the DC input impedance at a specified temperature (typically +25C). TCVFSS temperature coefficient of full scale span The percent change in full scale span per unit change in temperature relative to the full scale span at a specified temperature (typically +25C). TCVoff temperature coefficient of offset The percent change in offset per unit change in temperature relative to the offset at a specified temperature (typically +25C). Tstg storage temperature The temperature range at which the device, without any power applied, may be stored. tR response time The time required for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure. -- Temperature Hysteresis The difference in output at any temperature in the operating temperature range when the temperature is approached from the minimum operating temperature and when approached from the maximum operating temperature with zero pressure applied. VFSS full scale span voltage The change in output over the operating pressure range at a specified supply voltage. Voff offset voltage The output with zero differential pressure applied for a specified supply voltage or current. VS supply voltage dc The dc excitation voltage applied to the sensor. For precise circuit operation, a regulated supply should be used. VS max maximum supply voltage The maximum supply voltage that may be applied to a circuit or connected to the sensor. Zin input impedance The resistance measured between the positive and negative input terminals at a specified frequency with the output terminals open. For Motorola X-ducer, this is a resistance measurement only. Zout output impedance The resistance measured between the positive and negative output terminals at a specified frequency with the input terminals open. V/P sensitivity The change in output per unit change in pressure for a specified supply voltage. 3-446 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Section Four Safety and Alarm Integrated Circuits Motorola's Safety and Alarm Integrated Circuits (IC's) are low power, CMOS devices designed to meet a wide range of smoke detector applications at very competitive prices. Motorola has been producing both photoelectric and ionization safety and alarm IC's for more than 20 years. Found in consumer and commercial applications worldwide, these integrated circuits can be operated using a battery or AC power. In addition, these devices are designed to be used in stand alone units or as an interconnected system of up to 40 units. All of Motorola's safety and alarm IC's have component recognition from Underwriter's Laboratories and the newest devices meet the NFPA's new temporal - new tone horn pattern. Mini Selector Guide . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Data Sheets MC14467-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 3 MC14468 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 9 MC14578 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 15 MC14600 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19 MC145010 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 24 MC145011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 34 MC145012 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 44 MC145017 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-54 MC145018 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 60 Application Notes AN1690 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4- 66 AN4009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-70 Case Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-72 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-1 Freescale Semiconductor, Inc. Mini Selector Guide SAFETY AND ALARM INTEGRATED CIRCUITS Smoke Ion Product Operating Voltage (V) Horn Tone Interconnectable Primary Power Source Ordering Suffix Note MC14467 6 to 12 Continuous - Old Tone - 4/6 No DC P1 MC14468 6 to 12 Continuous - Old Tone - 4/6 Yes AC/DC P MC145017 6 to 12 Temporal - New Tone - NFPA Tone No DC P MC145018 6 to 12 Temporal - New Tone - NFPA Tone Yes AC/DC P Operating Voltage (V) Horn Tone Interconnectable Primary Power Source Ordering Suffix Note MC145010 6 to 12 Continuous - Old Tone - 4/6 Yes AC/DC P, DW, DWR2 MC145011 6 to 12 Continuous - Old Tone - 4/6 Yes AC P, DW, DWR2 MC145012 6 to 12 Temporal - New Tone - NFPA Tone Yes AC/DC P, DW, DWR2 Operating Voltage (V) Description Horn Modulation Primary Power Source Ordering Suffix Note 3.5 to 14 Micro-Power Comparator Plus Voltage Follower No Horn Driver AC/DC P Operating Voltage (V) Description Horn Tone(ms) Primary Power Source Ordering Suffix Note 6.0 to 12 Alarm Detection, Horn Driver, Low Battery Detection, LED Driver Continuous - Old Tone - 4/6 AC/DC P, DW, DWR2 Smoke Photo Freescale Semiconductor, Inc... Product Comparator Product MC14578 General Alarm Product MC14600 Note: P or P1 = 16-pin DIP, DW = SOIC 16-pin, DWR2 = SOIC 16-pin tape & reel 4-2 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA MC14467-1 Low-Power CMOS Ionization Smoke Detector IC The MC14467-1, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. 16 1 P SUFFIX PLASTIC DIP CASE 648-08 * Ionization Type with On-Chip FET Input Comparator Freescale Semiconductor, Inc... * Piezoelectric Horn Driver * Guard Outputs on Both Sides of Detect Input * Input-Production Diodes on the Detect Input ORDERING INFORMATION MC14467P1 PLASTIC DIP * Low-Battery Trip Point, Internally Set, can be Altered Via External Resistor * Detect Threshold, Internally Set, can be Altered Via External Resistor * Pulse Testing for Low Battery Uses LED for Battery Loading PIN ASSIGNMENT (16 PIN DIP) * Comparator Outputs for Detect and Low Battery * Internal Reverse Battery Protection Detect Comp. Out 1 16 Guard Hi-Z N/C 2 15 Detect Input Low V Set 3 14 Guard Lo-Z Low V Comp. Out 4 13 Sensitivity Set LED 5 12 Osc Capacitor VDD 6 11 Silver Timing Resistor 7 10 Brass Feedback 8 9 VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Rating Symbol DC Supply Voltage Value *0.5 to + 15 VDD Unit V Vin *0.25 to VDD + 0.25 DC Current Drain per Input Pin, Except Pin 15 = 1 mA I 10 mA DC Current Drain per Output Pin I 30 mA Input Voltage, All Inputs Except Pin 8 Storage Temperature Range Tstg *10 to +60 *55 to + 125 Reverse Battery Time tRB 5.0 Operating Temperature Range TA V C C s * Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that except for pin 8, Vin and Vout be constrained to the range VSS (Vin or Vout) VDD. For pin 8, refer to the Electrical Characteristics. v v REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-3 Freescale Semiconductor, Inc. MC14467-1 RECOMMENDED OPERATING CONDITIONS (Voltages referenced to VSS) Symbol Value Unit VDD 9.0 V Timing Capacitor -- 0.1 F Timing Resistor -- 8.2 M Battery Load (Resistor or LED) -- 10 mA Parameter Supply Voltage ELECTRICAL CHARACTERISTICS (Voltages referenced to VSS, TA = 25C) Symbol VDD Vdc Min Typ# Max Unit Operating Voltage VDD -- 6.0 -- 12 V Output Voltage Piezoelectric Horn Drivers (IOH = 16 mA) Comparators (IOH = 30 A) Piezoelectric Horn Drivers (IOL = +16 mA) Comparators (IOL = +30 A) VOH 7.2 9.0 7.2 9.0 6.3 8.5 -- -- -- 8.8 -- 0.1 -- -- 0.9 0.5 Output Voltage -- LED Driver, IOL = 10 mA VOL 7.2 -- -- 3.0 Output Impedance, Active Guard Pin 14 Pin 16 Lo-Z Hi-Z 9.0 9.0 -- -- -- -- 10 1000 Operating Current (Rbias = 8.2 M) IDD 9.0 12.0 -- -- 5.0 -- 9.0 12.0 Input Current -- Detect (40% R.H.) Freescale Semiconductor, Inc... Characteristic * * VOL V V V k A Iin 9.0 -- -- "1.0 pA Internal Set Voltage Low Battery Sensitivity Vlow Vset 9.0 -- 7.2 47 -- 50 7.8 53 V %VDD Hysteresis vhys 9.0 75 100 150 mV Offset Voltage (measured at Vin = VDD/2) Active Guard Detect Comparator VOS -- -- -- -- "100 "50 mV 9.0 9.0 Input Voltage Range, Pin 8 Vin -- VSS -10 -- VDD + 10 V Input Capacitance Cin -- -- 5.0 -- pF Common Mode Voltage Range, Pin 15 Vcm -- 0.6 -- VDD *2 V # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. 4-4 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14467-1 TIMING PARAMETERS (C = 0.1 F, Rbias = 8.2 M, VDD = 9.0 V, TA = 25C, See Figure 6) Characteristics Oscillator Period No Smoke Smoke Oscillator Rise Time Symbol Min Typ# Max Units tCI 1.34 32 1.67 40 2.0 48 s ms tr 8.0 10 12 ms Horn Output (During Smoke) On Time Off Time PWon PWoff 120 60 160 80 208 104 ms ms LED Output Between Pulses On Time tLED PWon 32 8.0 40 10 48 12 s ms Horn Output (During Low Battery) On Time Between Pulses ton toff 8.0 32 10 40 12 48 ms s Freescale Semiconductor, Inc... # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. VDD 8 VDD 11 4 80 K 3 PIEZOELECTRIC HORN DRIVER LOW BATTERY COMP. - LATCH + 10 7 VDD OSCILLATOR TIMER 1045 K 12 VDD 5 6 9 13 + LED DRIVER LATCH 1125 K - 1 15 DETECT INPUT + - 14 LO-Z VDD 16 HI-Z ACTIVE GUARD Figure 1. Block Diagram Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-5 Freescale Semiconductor, Inc. MC14467-1 100.0 10.0 TA = 25C TA = 25C ID , DRAIN CURRENT (mA) ID , DRAIN CURRENT (mA) VDD = 9.0 Vdc 10.0 VDD = 7.2 Vdc 1.0 0.1 VDD = 9.0 Vdc or 7.2 Vdc 1.0 0.1 P-CH SOURCE AND N-CH SINK CURRENT 0.01 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 8 9 10 9 10 Figure 3. Typical Comparator Output I-V Characteristic 1000.0 1000.0 TA = 25C ID , DRAIN CURRENT (mA) TA = 25C VDD = 9.0 Vdc 100.0 VDD = 9.0 Vdc 100.0 VDD = 7.2 Vdc 10.0 VDD = 7.2 Vdc 10.0 P-CH SOURCE CURRENT 1.0 0 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 2. Typical LED Output I-V Characteristic ID , DRAIN CURRENT (mA) Freescale Semiconductor, Inc... VDS, DRAIN TO SOURCE VOLTAGE (Vdc) 1 2 3 4 5 6 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) N-CH SINK CURRENT 8 9 10 1.0 0 1 2 3 4 5 6 7 8 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 4. Typical P Horn Driver Output I-V Characteristic 4-6 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14467-1 DEVICE OPERATION Freescale Semiconductor, Inc... TIMING The internal oscillator of the MC14467-1 operates with a period of 1.67 seconds during no-smoke conditions. Each 1.67 seconds, internal power is applied to the entire IC and a check is made for smoke, except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. DETECT CIRCUITRY If smoke is detected, the oscillator period becomes 40 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 160 ms on, 80 ms off. During the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. During smoke conditions the low battery alarm is inhibited, but the LED pulses at a 1.0 Hz rate. An active guard is provided on both pins adjacent to the detect input. The voltage at these pins will be within 100 mV of the input signal. This will keep surface leakage currents to a minimum and provide a method of measuring the input voltage without loading the ionization chamber. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. SENSITIVITY/LOW BATTERY THRESHOLDS Both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see Figure 1) connected between VDD and VSS. These voltages can be altered by external resistors connected from pins 3 or 13 to either VDD or VSS. There will be a slight interaction here due to the common voltage divider network. The sensitivity threshold can also be set by adjusting the smoke chamber ionization source. TEST MODE Since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or time-consuming. By forcing Pin 12 to VSS, the power strobing is bypassed and the outputs, Pins 1 and 4, constantly show smoke/no smoke and good battery/low battery, respectively. Pin 1 = VDD for smoke and Pin 4 = VDD for low battery. In this mode and during the 10 ms power strobe, chip current rises to approximately 50 A. LED PULSE The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 10 ms. If the LED is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 mA. HYSTERESIS When smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. This yields approximately 100 mV of hysteresis and reduces false triggering. 1M 1M TEST 1 16 MC14467-1 330 0.1 F + 2 15 3 14 4 13 5 12 6 11 7 10 8 9 0.1 F 8.2 M 9V 1.5 M* 0.001* F 220 k* *NOTE: Component values may change depending on type of piezoelectric horn used. Figure 5. Typical Application as Ionization Smoke Detector Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-7 Freescale Semiconductor, Inc. MC14467-1 Standby No Smoke/ No Low Battery Smoke/Low Battery Smoke/No Low Battery 10 ms No Smoke/Low Battery 1.67 s 40 ms Oscillator (Pin 12) Detect Out (Pin 1) Low Battery Out (Pin 4) Hysteresis (Internal) (Pin 13 ) (Pin 14) Sample (Internal) Smoke Freescale Semiconductor, Inc... Horn (Pin 10 and 11) (Note 1) Battery Test LED (Pin 5) Suppressed Chirp (Note 3) (Note 3) 24 Clock Cycles 24 Clock Cycles (0.96 s) 24 Clock Cycles (40S) 6 Clock Cycles (10.0s) Figure 6. Timing Diagram NOTES: 1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off. 2. Comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke). 3. Low battery comparator information is latched only during LED pulse. 4. 100 mV p-p swing. X 4-8 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA MC14468 Low-Power CMOS Ionization Smoke Detector IC with Interconnect 16 1 The MC14468, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. P SUFFIX PLASTIC DIP CASE 648-08 Freescale Semiconductor, Inc... * Ionization Type with On-Chip FET Input Comparator * Piezoelectric Horn Driver ORDERING INFORMATION MC14468P PLASTIC DIP * Guard Outputs on Both Sides of Detect Input * Input-Production Diodes on the Detect Input * Low-Battery Trip Point, Internally Set, can be Altered Via External Resistor PIN ASSIGNMENT (16 PIN DIP) * Detect Threshold, Internally Set, can be Altered Via External Resistor * Pulse Testing for Low Battery Uses LED for Battery Loading * Comparator Output for Detect * Internal Reverse Battery Protection * Strobe Output for External Trim Resistors * I/O Pin Allows Up to 40 Units to be Connected for Common Signaling * Power-On Reset Prevents False Alarms on Battery Change Detect Comp. Out 1 16 Guard Hi-Z I/O 2 15 Detect Input Low V Set 3 14 Guard Lo-Z Strobe Out 4 13 Sensitivity Set LED 5 12 Osc Capacitor VDD 6 11 Silver Timing Resistor 7 10 Brass Feedback 8 9 VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Rating Symbol DC Supply Voltage Value *0.5 to + 15 VDD Unit V Vin *0.25 to VDD + 0.25 DC Current Drain per Input Pin, Except Pin 15 = 1 mA I 10 mA DC Current Drain per Output Pin I 30 mA Input Voltage, All Inputs Except Pin 8 Storage Temperature Range Tstg *10 to + 60 *55 to + 125 Reverse Battery Time tRB 5.0 Operating Temperature Range TA V C C s * Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that Vin and Vout be constrained to the range VSS (Vin or Vout) VDD. v v REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-9 Freescale Semiconductor, Inc. MC14468 RECOMMENDED OPERATING CONDITIONS (Voltages referenced to VSS) Symbol Value Unit VDD 9.0 V Timing Capacitor -- 0.1 F Timing Resistor -- 8.2 M Battery Load (Resistor or LED) -- 10 mA Parameter Supply Voltage ELECTRICAL CHARACTERISTICS (TA = 25C) Symbol VDD Vdc Min Typ# Max Unit Operating Voltage VDD -- 6.0 -- 12 V Output Voltage Piezoelectric Horn Drivers (IOH = 16 mA) Comparators (IOH = 30 A) Piezoelectric Horn Drivers (IOL = +16 mA) Comparators (IOL = +30 A) VOH 7.2 9.0 7.2 9.0 6.3 8.5 -- -- -- 8.8 -- 0.1 -- -- 0.9 0.5 Output Voltage -- LED Driver, IOL = 10 mA VOL 7.2 -- -- 3.0 Output Impedance, Active Guard Pin 14 Pin 16 Lo-Z Hi-Z 9.0 9.0 -- -- -- -- 10 1000 Operating Current (Rbias = 8.2 M) IDD 9.0 12.0 -- -- 5.0 -- 9.0 12.0 Input Current -- Detect (40% R.H.) Iin 9.0 -- -- Input Current, Pin 8 Iin 9.0 -- -- Input Current @ 50C, Pin 15 Iin -- -- -- Internal Set Voltage Low Battery Sensitivity Vlow Vset 9.0 -- 7.2 47 Hysteresis vhys 9.0 Offset Voltage (measured at Vin = VDD/2) Active Guard Detect Comparator VOS 9.0 9.0 Freescale Semiconductor, Inc... Characteristic * * VOL V V V k A "1.0 "0.1 "6.0 A -- 50 7.8 53 V %VDD 75 100 150 mV -- -- "100 "50 mV -- -- *10 pA Input Voltage Range, Pin 8 Vin -- -- VDD + 10 V Input Capacitance Cin -- -- 5.0 -- pF Common Mode Voltage Range, Pin 15 Vcm -- 0.6 -- I/O Current, Pin 2 Input, VIH = VDD 2 Output, VOH = VDD 2 IIH IOH -- -- *4.0 25 -- -- * * VSS pA VDD *2 100 *16 V A mA # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. 4-10 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14468 TIMING PARAMETERS (C = 0.1 F, Rbias = 8.2 M, VDD = 9.0 V, TA = 25C, See Figure 6) Characteristics Oscillator Period Symbol Min Typ# Max Units tCI 1.34 32 1.67 40 2.0 48 s ms No Smoke Smoke Oscillator Rise Time tr 8.0 10 12 ms Horn Output (During Smoke) On Time Off Time PWon PWoff 120 60 160 80 208 104 ms ms LED Output Between Pulses On Time tLED PWon 32 8.0 40 10 48 12 s ms Horn Output (During Low Battery) On Time Between Pulses ton toff 8.0 32 10 40 12 48 ms s Freescale Semiconductor, Inc... # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. TO OTHER UNITS VDD VDD I/O FEEDBACK 8 2 45 K - LOW V SET DETECT COMPARATOR OUT 3 11 LOW BATTERY COMPARATOR + SILVER 10 BRASS 1 ALARM LOGIC 280 K 13 DETECT COMPARATOR + POWER-ON RESET - 325 K STROBE OUT 4 15 DETECT INPUT GUARD AMP + LO-Z 14 VDD HI-Z 5 OSC AND TIMING LED 16 - VDD = PIN 6 VSS = PIN 9 12 7 VDD Figure 1. Block Diagram Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-11 Freescale Semiconductor, Inc. MC14468 100.0 10.0 TA = 25C TA = 25C ID , DRAIN CURRENT (mA) ID , DRAIN CURRENT (mA) VDD = 9.0 Vdc 10.0 VDD = 7.2 Vdc 1.0 0.1 VDD = 9.0 Vdc or 7.2 Vdc 1.0 0.1 P-CH SOURCE AND N-CH SINK CURRENT 0.01 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 8 9 10 9 10 Figure 3. Typical Comparator Output I-V Characteristic 1000.0 1000.0 TA = 25C ID , DRAIN CURRENT (mA) TA = 25C VDD = 9.0 Vdc 100.0 VDD = 9.0 Vdc 100.0 VDD = 7.2 Vdc 10.0 VDD = 7.2 Vdc 10.0 P-CH SOURCE CURRENT 1.0 0 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 2. Typical LED Output I-V Characteristic ID , DRAIN CURRENT (mA) Freescale Semiconductor, Inc... VDS, DRAIN TO SOURCE VOLTAGE (Vdc) 1 2 3 4 5 6 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) N-CH SINK CURRENT 8 9 10 1.0 0 1 2 3 4 5 6 7 8 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 4. Typical P Horn Driver Output I-V Characteristic 4-12 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14468 DEVICE OPERATION Freescale Semiconductor, Inc... TIMING The internal oscillator of the MC14468 operates with a period of 1.67 seconds during no-smoke conditions. Each 1.67 seconds, internal power is applied to the entire IC and a check is made for smoke, except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. DETECT CIRCUITRY If smoke is detected, the oscillator period becomes 40 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 160 ms on, 80 ms off. During the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. During local smoke conditions the low battery alarm is inhibited, but the LED pulses at a 1.0 Hz rate. In remote smoke, the LED is inhibited as well. An active guard is provided on both pins adjacent to the detect input. The voltage at these pins will be within 100 mV of the input signal. This will keep surface leakage currents to a minimum and provide a method of measuring the input voltage without loading the ionization chamber. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. INTERCONNECT The I/O (Pin 2), in combination with VSS, is used to interconnect up to 40 remote units for common signaling. A Local Smoke condition activates a current limited output driver, thereby signaling Remote Smoke to interconnected units. A small current sink improves noise immunity during non- smoke conditions. Remote units at lower voltages do not draw excessive current from a sending unit at a higher voltage. The I/O is disabled for three oscillator cycles after power up, to eliminate false alarming of remote units when the battery is changed. SENSITIVITY/LOW BATTERY THRESHOLDS Both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see Figure 1) connected between VDD and VSS. These voltages can be altered by external resistors connected from pins 3 or 13 to either VDD or VSS. There will be a slight interaction here due to the common voltage divider network. The sensitivity threshold can also be set by adjusting the smoke chamber ionization source. TEST MODE Since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or time-consuming. By forcing Pin 12 to VSS, the power strobing is bypassed and the output, Pin 1, constantly shows smoke/no smoke. Pin 1 = VDD for smoke. In this mode and during the 10 ms power strobe, chip current rises to approximately 50 A. LED PULSE The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 10 ms. If the LED is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 mA. HYSTERESIS When smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. This yields approximately 100 mV of hysteresis and reduces false triggering. 1M 1M TEST 1 16 MC14468 TO OTHER UNITS 330 0.1 F + 2 15 3 14 4 13 5 12 6 11 7 10 8 9 0.1 F 8.2 M 9V *NOTE: Component values may change depending on type of piezoelectric horn used. 1.5 M* 0.001 F 220 k* Figure 5. Typical Application as Ionization Smoke Detector Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-13 Freescale Semiconductor, Inc. MC14468 Standby No Smoke/ No Low Battery Smoke/Low Battery Smoke/No Low Battery 10 ms No Smoke/Low Battery 1.67 s 40 ms Oscillator (Pin 12) Detect Out (Pin 1) Low Battery (Internal) Hysteresis (Internal) (Pin 13 ) (Pin 14) Sample (Internal) Smoke Low = Disable Freescale Semiconductor, Inc... Horn High = Enable (Pin 10 and 11) (Note 1) Battery Test LED (Pin 5) Suppressed Chirp (Note 3) (Note 3) 24 Clock Cycles 24 Clock Cycles (0.96 s) 24 Clock Cycles 6 Clock Cycles (10.0 s) (40S) Strobe Out (Pin 14) I/O (Pin 2) Output (Local) I/O (Pin 2) Input (Remote) LED Note: Horn Modulation Not Self-Completing (Suppressed LED for Remote Only) Figure 6. Timing Diagram NOTES: 1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off. 2. Comparators are strobed on once per clock cycle (1.67 s for no smoke, 40 ms for smoke). 3. Low battery comparator information is latched only during LED pulse. 4. 100 mV p-p swing. X 4-14 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MOTOROLA SEMICONDUCTOR TECHNICAL DATA MC14578 CMOS Micro-Power Comparator plus Voltage Follower Freescale Semiconductor, Inc... 16 1 The MC14578 is an analog building block consisting of a very-high input impedance comparator. The voltage follower allows monitoring the noninverting input of the comparator without loading. Four enhancement-mode MOSFETs are also included on chip. These FETs can be externally configured as open-drain or totem-pole outputs. The drains have on-chip static-protecting diodes. Therefore, the output voltage must be maintained between VSS and VDD. The chip requires one external component. A 3.9 M 10% resistor must be connected from the Rbias pin to VDD. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. P SUFFIX PLASTIC DIP CASE 648-08 " * Applications: Pulse Shapers Threshold Detectors Low-Battery Detectors ORDERING INFORMATION MC14578P PLASTIC DIP PIN ASSIGNMENT Line-Powered Smoke Detectors Liquid/Moisture Sensors CO Detector and Micro Interface VDD 1 16 NC COMP OUT 2 15 IN + * Operating Temperature Range: IN A 3 14 NC * Input Current (IN + Pin): IN B 4 13 BUFF OUT OUT A 5 12 IN-- OUT B 6 11 Rbias IN C 7 10 VSS OUT C1 8 9 * Operating Voltage Range: 3.5 to 14 V *30 to 70C "1 pA @ 25C (DIP Only) * Quiescent Current: 10 A @ 25C * Electrostatic Discharge (ESD) Protection Circuitry on All Pins OUT C2 LOGIC DETAIL IN+ * IN 15 12 + COMP - 2 COMP OUT 3 IN A 5 Rbias 11 BIAS CKT + BUFF - 6 13 IN B 9 OUT A IN C 7 OUT B 8 OUT C2 OUT C1 4 BUFF OUT PIN 1 = VDD PIN 10 = VSS PINS 14, 16 = NO CONNECTION REV 1 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-15 Freescale Semiconductor, Inc. MC14578 MAXIMUM RATINGS* (Voltages Referenced to VSS) Parameter Symbol VDD DC Supply Voltage Vin DC Input Voltage Vout DC Output Voltage Iin DC Input Current, Except IN + Iin DC Input Current, IN + Iout DC Output Current, per Pin IDD DC Supply Current, VDD and VSS Pins PD Power Dissipation, per Package Tstg Storage Temperature TL Value *0.5 to +14 *0.5 to VDD +0.5 *0.5 to VDD +0.5 "10 "1.0 "25 "50 500 *65 to +150 Lead Temperature (10-Second Soldering) 260 Unit V V V mA mA mA mA mW C C Freescale Semiconductor, Inc... *Maximum Ratings are those values beyond which damage to the device may occur. This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this high-impedance circuit. For proper operation, Vin and Vout should be constrained to the range VSS (Vin or Vout) VDD. Unused inputs must always be tied to an appropriate logic voltage level (e.g., either V SS or VDD). Unused outputs must be left open. 4-16 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14578 ELECTRICAL CHARACTERISTICS (Voltages Referenced to VSS, Rbias = 3.9 M to VDD, TA = -30 to 70C Unless Otherwise Indicated) Symbol Freescale Semiconductor, Inc... VDD Parameter Test Condition Power Supply Voltage Range VDD V Guaranteed Limit Unit -- 3.5 to 14.0 V VIL Maximum Low-Level Input Voltage, MOSFETs Wired as Inverters; i.e., IN A tied to IN B, OUT A to OUT B, OUT C1 to OUT C2. Vout = 9.0 V, |Iout| t1 A 10.0 2.0 V VIH Minimum High-Level Input Voltage, MOSFETs Wired as Inverters; i.e., IN A tied to IN B, OUT A to OUT B, OUT C1 to OUT C2. Vout = 1.0 V, |Iout| t1 A 10.0 8.0 V VIO Comparator Input Offset Voltage TA = 25C, Over Common Mode Range 10.0 "50 mV TA = 0 to 50C, Over Common Mode Range 3.5 to 14.0 VCM Comparator Common Mode Voltage Range VOL Maximum Low-Level Comparator Output Voltage IN +: Vin = VSS, IN Iout = 30 A VOH Minimum High-Level Comparator Output Voltage IN +: Vin = VDD, IN Iout = 30 A VOO Buffer Amp Output Offset Voltage Rload = 10 M to VDD or VSS, Over Common Mode Range VOL Maximum Low-Level Output Voltage, MOSFETs Wired as Inverters Inverters; i.e., i e IN A tied to IN B, B OUT A to OUT B, OUT C1 to OUT C2. VOH Iin 3.5 to 14.0 0.7 to VDD 1.5 V 10.0 0.5 V 10.0 9.5 V -- "100 mV OUT C1, OUT C2: Iout = 1.1 mA 10.0 0.5 V OUT A, OUT B: Iout = 270 A 10.0 0.5 V Minimum High-Level Output Voltage, MOSFETs Wired as Inverters Inverters; i.e., i e IN A tied to IN B, B OUT A to OUT B, OUT C1 to OUT C2. OUT C1, OUT C2: Iout = 10.0 9.5 V OUT A, OUT B: Iout = 270 A 10.0 9.5 V Maximum Input Leakage Current IN + (DIP Only) TA = 25C, 40% R.H., Vin = VSS or VDD 10.0 "1.0 pA IN + (DIP Only) TA = 50C, Vin = VSS or VDD 10.0 "6.0 Vin = VSS or VDD 10.0 IN A, IN C: Vin = VDD, OUT A, OUT C2: Vout = VSS or VDD 10.0 "40 "100 IN B, IN C: Vin = VSS, OUT B, OUT C1: Vout = VSS or VDD 10.0 "100 TA = 25C IN A, IN B, IN C: Vin = VSS or VDD, |VIN + VIN | = 100 mV, Iout = 0 A 10.0 10 A -- -- 5.0 15 pF IN + (SOG), IN A, IN B, IN C, IN IOZ IDD "75 * Maximum Off-State MOSFET Leakage Current Maximum Quiescent Current * *: Vin = VDD, *: Vin = VSS, *1.1 mA * nA nA * * Cin Maximum Input Capacitance Motorola Sensor Device Data IN + Other Inputs f = 1 kHz www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-17 Freescale Semiconductor, Inc. MC14578 APPLICATIONS INFORMATION V+ V+ 1 MC14578 VDD NC 16 R1 V+ 2 3 Freescale Semiconductor, Inc... 4 R5 6.8 k LOW-BATTERY INDICATOR D2 5 6 COMP OUT IN + IN A NC IN B BUFF OUT * OUT A IN OUT B Rbias 15 R3 14 R2 13 V+ 12 D1 R4 11 3.9 M 7 8 IN C VSS OUT C1 OUT C2 10 9 OUTPUT NOTE: IN + and IN HIGH = BATTERY LOW LOW = BATTERY OK * have very high input impedance. Interconnect to these pins should be as short as possible. Figure 1. Low-Battery Detector EXAMPLE VALUES Near the switchpoint, the comparator output in the circuit of Figure 1 may chatter or oscillate. This oscillation appears on the signal labelled OUTPUT. In some cases, the oscillation in the transition region will not cause problems. For example, an MPU reading OUTPUT could sample the signal two or three times to ensure a solid level is attained. But, in a low battery detector, this probably is not necessary. To eliminate comparator chatter, hysteresis can be added as shown in Figure 2. The circuit of Figure 2 requires slightly more operating current than the Figure 1 arrangement. R1 R2 R3 Nominal Trip Point 470 k 1.3 M 20 k 4.08 V 820 k 1.2 M 39 k 5.05 V 1.2 M 1.2 M 62 k 6.00 V 12 - + R6 2 15 R7 Figure 2. Adding Hysteresis 4-18 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low-Power CMOS MC14600 ALARM IC with Horn Driver The MC14600 Alarm IC is designed to simplify the process of interfacing an alarm level voltage condition to a piezoelectric horn and/or LED. With an extremely low average current requirement and an integrated low battery detect feature, the part is ideally suited to battery operated applications. The MC14600 is easily configured with a minimum number of external components to serve a wide range of applications and circuit configurations. Typical applications include intrusion alarms, moisture or water ingress alarms, and personal safety devices. 16 1 P SUFFIX PLASTIC DIP CASE 648-08 Freescale Semiconductor, Inc... * High Impedance, FET Input Comparator * Comparator Outputs for Low Battery and Alarm Detect * Alarm Detect Threshold Easily Established with 2 Resistor * Integrated Oscillator and Piezoelectric Horn Driver 16 * Low Battery Trip Point Set Internally (Altered Externally) 1 * Horn "Chirp'' During Low Battery Condition DW SUFFIX SOIC PACKAGE CASE 751G-03 * Pulsed LED Drive Output * Reverse Battery Protection * Input Protection Diodes on the Detect Input * Average Supply Current: 9 A ORDERING INFORMATION MC14600P MC14600DW MC14600DWR2 PLASTIC DIP SOIC SOIC TAPE & REEL PIN ASSIGNMENT (16 PIN DIP) MAXIMUM RATINGS* (Voltages referenced to VSS) Rating DC Supply Voltage Input Voltage, All Inputs Except Pin 8 DC Current Drain per Input Pin, Except Pin 15 = 1 mA DC Current Drain per Output Pin Symbol VDD Value Unit *0.5 to + 15 Vin *0.25 to VDD + 0.25 I 10 I 30 Storage Temperature Range Tstg Reverse Battery Time tRB 5.0 TA V mA *10 to + 60C *55 to + 125 Operating Temperature Range V Detect Comp. Out 1 16 Guard N/C 2 15 Alarm Detect Input Low V Set 3 14 N/C Low V Comp. Out 4 13 Alarm Threshold LED 5 12 Osc Capacitor mA VDD 6 11 Horn Out 2 C Timing Resistor Horn Feedback 7 10 Horn Out 1 8 9 C VSS s * Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that Vin and Vout be constrained to the range VSS (Vin or Vout) VDD. v v REV 3 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-19 Freescale Semiconductor, Inc. MC14600 RECOMMENDED OPERATING CONDITIONS (Voltages referenced to VSS) Parameter Supply Voltage LED (Pin 5) Load Symbol Value Unit VDD 9.0 V -- 10 mA ELECTRICAL CHARACTERISTICS (Voltages referenced to VSS, TA = 25C) Characteristic Freescale Semiconductor, Inc... Operating Voltage Output Voltage Piezoelectric Horn Drivers (IOH = +16 mA) Comparators (IOH = +30 A) Piezoelectric Horn Drivers (IOL = 16 mA) Comparators (IOL = 30 A) (IOL = 200 A) Pin # Symbol VDD Vdc Min Typ Max Unit 6 VDD -- 6.0 -- 12 V 6.5 8.5 -- -- -- -- 8.8 -- 0.1 -- -- -- 0.9 0.5 0.5 V VOH V 10,11 4 10,11 4 1 VOL 7.4 9.0 7.4 9.0 -- Output Voltage -- LED Driver, IOL = 10 mA 5 VOL 7.2 -- -- 2.0 V Output Impedance, Active Guard 16 Hi-Z 9.0 -- -- 1000 k Standby Current (Rbias = 8.2 M) -- IDD 9.0 12.0 -- -- 5.0 -- 9.0 12.0 A Input Leakage Current 1 8 13 -- Iin -- 9.0 9.0 9.0 -- -- -- -- -- -- "30 "0.1 "30 nA A nA 1 -- -- -- -- 2.50 -- -- -- -- 8.00 mA mA 6 Vlow 9.0 7.2 -- 7.8 V * * * Detect Comp. Out V=3V V=9V Low Battery Threshold Voltage (Pin 3 open) Offset Voltage (measured at Vin = VDD/2) Active Guard Detect Comparator VOS 16 13,15 9.0 9.0 -- -- -- -- "100 "50 mV Input Voltage Range 8 Vin -- VSS -10 -- VDD + 10 V Input Capacitance (to VSS @ 1 khz) 15 Cin -- -- 5.0 -- pF 13,15 Vcm -- 1.5 -- VDD -2 V All pins except 15 15 -- -- -- -- V -- -- -- -- Common Mode Voltage Range Breakdown Voltage Human Body Models per MIL-STD-883 Method 3015 "500 "400 # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. 4-20 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC14600 TIMING PARAMETERS (Cosc = 0.1 F, Rbias = 8.2 M, VDD = 9.0 V, TA = 25C, See Figure 2) Characteristics Oscillator Period (1 Clock Cycle = 1 Oscillator Period) No Alarm Alarm Freescale Semiconductor, Inc... Oscillator Pulse Width (No Alarm and Alarm Condition) Pin # Symbol Min Max Units 12 tCI -- 1.25 30 2.25 52 s ms 3,4,5,13 tr 7.0 13 ms LED Output Period No Alarm Alarm 5 tLED -- 30 .71 52 1.25 s ms Alarm Horn Output Hi Time Low Time 10,11 ton toff 120 60 208 104 ms ms Low Battery Horn Output Hi Time Between Pulses 10,11 ton toff 7.0 30 13 52 ms s VDD VDD LOW V COMP. OUT - LOW V SET DETECT COMPARATOR OUT 3 11 LOW BATTERY COMPARATOR + 1 ALARM 13 THRESHOLD HORN FEEDBACK 8 4 10 HORN OUT 1 ALARM LOGIC - HORN OUT 2 DETECT COMPARATOR + ALARM DETECT 15 INPUT GUARD AMP + VDD OSC AND TIMING HI-Z 5 LED 16 - VDD = PIN 6 VSS = PIN 9 Cosc 12 7 Rbias VDD Figure 1. Block Diagram Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-21 Freescale Semiconductor, Inc. MC14600 DEVICE OPERATION Freescale Semiconductor, Inc... TIMING The internal oscillator of the MC14600 operates with a period of 1.65 seconds during no-alarm conditions. Each 1.65 seconds, internal power is applied to the entire IC and a check is made for an alarm input level except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in alarm). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. DETECT CIRCUITRY If an alarm condition is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 167 ms on, 83 ms off. During the off time, alarm detect input (Pin 15) is again checked and will inhibit further horn output if no alarm condition is sensed. During alarm conditions the low battery chirp is inhibited, and the LED pulses at a 1.0 Hz rate. An active guard is provided on a pin adjacent to the detect input (Pin 16). The voltage at this pin will be within 100 mV of the input signal. Pin 16 will allow monitoring of the input signal at pin 15 through a buffer. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. LOW BATTERY THRESHOLD The low battery voltage level is set internally by a voltage divider connected between VDD and VSS. This voltage can be altered by external resistors connected from pin 3 to either VDD or VSS. A resistor to VDD will decrease the threshold while a resistor to GND will increase it. ALARM THRESHOLD (SENSITIVITY) The alarm condition voltage level is set externally through Pin 13. A voltage divider can be used to set the alarm trip point. Pin 13 is connected internally to the negative input of the detect comparator. LED PULSE The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 10 ms. If the LED is not used, it should be replaced with an equivalent resistor so that the battery loading remains at 10 mA. VDD Rp 1 16 MC14600 2 15 VDD VDD 14 4 13 5 12 6 11 7 10 8 9 R1 330 Rbias 0.1 F 3 DETECT INPUT R2 COSC 1.5 M* 0.001 F 220 k* *NOTE: Component values may change depending on type of piezoelectric horn used. Figure 2. Typical Application Components 4-22 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. OSC PIN 12 1 2 3 4 5 6 7 8 9 23 24 1 6 12 MC14600 18 ALARM - N -Y NO ALARM NO LOW BAT LOW BATT COMP (PIN 4) ALARM NO ALARM LATCH ALARM CONDITION LOW BATT COMP DETECT OUT (PIN 1) Freescale Semiconductor, Inc... OSC PIN 12 ALARM - N -Y NO ALARM, LOW BATTERY HORN (PINS 10 AND 11) 24 LOW BATTERY CHIRP LED - OFF - ON DETECT OUT (PIN 1) & (NOTE 1) HORN - ON - OFF 24 CLOCKS LED - OFF - ON 24 CLOCKS Figure 3. MC14600 Timing Diagram NOTES: 1. Horn modulation is self-completing. When going from Alarm to No Alarm, the alarm condition will terminate only when horn is off. 2. Comparators are strobed once per cycle. 3. Low battery comparator information is latched only during LED pulse. 4. Current source required into Pin 1. 5. Alarm Condition can initiate on any clock pulse except 1 and 7. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-23 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Photoelectric Smoke MC145010 Freescale Semiconductor, Inc... Detector IC with I/O The CMOS MC145010 is an advanced smoke detector component containing sophisticated very-low-power analog and digital circuitry. The IC is used with an infrared photoelectric chamber. Detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. When detection occurs, a pulsating alarm is sounded via on-chip push-pull drivers and an external piezoelectric transducer. The variable-gain photo amplifier allows direct interface to IR detectors (photodiodes). Two external capacitors, C1 and C2, C1 being the larger, determine the gain settings. Low gain is selected by the IC during most of the standby state. Medium gain is selected during a local-smoke condition. High gain is used during pushbutton test. During standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain, also. The I/O pin, in combination with VSS, can be used to interconnect up to 40 units for common signaling. An on-chip current sink provides noise immunity when the I/O is an input. A local-smoke condition activates the short-circuit- protected I/O driver, thereby signaling remote smoke to the interconnected units. Additionally, the I/O pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate auto-dialers. While in standby, the low-supply detection circuitry conducts periodic checks using a pulsed load current from the LED pin. The trip point is set using two external resistors. The supply for the MC145010 can be a 9 V battery. A visible LED flash accompanying a pulsating audible alarm indicates a local-smoke condition. A pulsating audible alarm with no LED flash indicates a remote-smoke condition. A beep or chirp occurring virtually simultaneously with an LED flash indicates a low-supply condition. A beep occurring half-way between LED flashes indicates degraded chamber sensitivity. A low-supply condition does not affect the smoke detection capability if VDD 6 V. Therefore, the low-supply condition and degraded chamber sensitivity can be further distinguished by performing a pushbutton (chamber) test. 16 1 P SUFFIX PLASTIC DIP CASE 648-08 16 1 DW SUFFIX SOIC PACKAGE CASE 751G-03 ORDERING INFORMATION MC145010P PLASTIC DIP MC145010DW SOIC PACKAGE PIN ASSIGNMENT * Circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 Specifications C1 1 16 Test C2 2 15 Low-Supply Trip Detect 3 14 VSS Strobe 4 13 R1 * Power-On Reset Places IC in Standby Mode (Non-Alarm State) VDD 5 12 Osc * Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins IRED 6 11 LED I/O 7 10 Feedback Brass 8 9 * Operating Voltage Range: 6 to 12 V * Operating Temperature Range: - 10 to 60C * Average Supply Current: 12 A * Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors * Ideal for battery powered applications. Silver REV 4 4-24 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145010 BLOCK DIAGRAM C1 C2 1 2 3 AMP OSC R1 TEST 12 GAIN ZERO VDD - 3.5 V REF - COMP + SMOKE GATE ON/OFF OSC TIMING LOGIC 13 16 GATE ON/OFF 7 ALARM LOGIC LOW SUPPLY DETECT HORN MODULATOR AND DRIVER 8 9 10 6 VDD - 5 V REF 11 Freescale Semiconductor, Inc... STROBE 4 - COMP + LOW-SUPPLY 15 TRIP I/O BRASS SILVER FEEDBACK IRED LED PIN 5 = VDD PIN 14 = VSS MAXIMUM RATINGS* (Voltages Referenced to VSS) Symbol VDD Parameter *0.5 to +12 DC Supply Voltage Vin DC Input Voltage Iin DC Input Current, per Pin C1, C2, Detect Osc, Low-Supply Trip I/O Feedback Test Iout DC Output Current, per Pin IDD DC Supply Current, VDD and VSS Pins PD Power Dissipation in Still Air, Tstg Storage Temperature TL Value *0.25 to VDD +0.25 *0.25 to VDD +0.25 *0.25 to VDD +10 *15 to +25 *1.0 to VDD +0.25 "10 "25 +25 / *150 5 Seconds Continuous Lead Temperature, 1 mm from Case for 10 Seconds 1200** 350*** Unit V V mA mA mA mW *55 to +125 C 260 C * Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the limits in the Electrical Characteristics tables. ** Derating: - 12 mW/C from 25 to 60C. *** Derating: - 3.5 mW/C from 25 to 60C. This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this high-impedance circuit. For proper operation, Vin and Vout should be constrained to the range VSS (Vin or Vout) VDD except for the I/O, which can exceed VDD, and the Test input, which can go below VSS. Unused inputs must always be tied to an appropriate logic voltage level (e.g., either VSS or VDD). Unused outputs and/or an unused I/O must be left open. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-25 Freescale Semiconductor, Inc. MC145010 ELECTRICAL CHARACTERISTICS (TA = - 10 to 60C Unless Otherwise Indicated, Voltages Referenced to VSS) Freescale Semiconductor, Inc... Symbol Parameter Test Condition VDD V Min Max Unit -- 6.0 12 V -- 6.5 7.8 V VDD Power Supply Voltage Range VTH Supply Threshold Voltage, Low-Supply Alarm Low-Supply Trip: Vin = VDD/3 IDD Average Operating Supply Current (per Package) Standby Configured per Figure 5 12.0 -- 12 A iDD Peak Supply Current (per Package) During Strobe On, IRED Off Configured per Figure 5 12.0 -- 2.0 mA During Strobe On, IRED On Configured per Figure 5 12.0 -- 3.0 VIL Low-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 -- -- -- 1.5 2.7 7.0 V VIH High-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 3.2 6.3 8.5 -- -- -- V Vin = VSS or VDD Vin = VSS or VDD Vin = VSS or VDD 12.0 12.0 12.0 -- -- -- 100 100 100 nA Iin Input Current OSC, Detect Low-Supply Trip Feedback IIL Low-Level Input Current Test Vin = VSS 12.0 -- -1 A IIH Pull-Down Current Test I/O Vin = VDD No Local Smoke, Vin = VDD No Local Smoke, Vin = 17 V 9.0 9.0 12.0 0.5 25 -- 10 100 140 A -- -- 0.6 1.0 V VOL Low-Level Output Voltage LED Silver, Brass Iout = 10 mA Iout = 16 mA 6.5 6.5 VOH High-Level Output Voltage Silver, Brass Iout = - 16 mA 6.5 5.5 -- V Vout Output Voltage (For Line Regulation, See Pin Descriptions) Inactive, Iout = -1 A Active, Iout = 100 A to 500 A (Load Regulation) -- 9.0 VDD - 0.1 VDD - 4.4 -- VDD - 5.6 V Inactive, Iout = 1 A Active, Iout = 6 mA (Load Regulation) -- 9.0 -- 2.25* 0.1 3.75* Local Smoke, Vout = 4.5 V 6.5 -4 -- Local Smoke, Vout = VSS (Short Circuit Current) 12.0 -- - 16 Vout = VSS or VDD Strobe IRED IOH High-Level Output Current I/O mA 12.0 -- 1 A C1, C2, Detect Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- VDD - 4 VDD - 2 V Internal Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- IOZ Off-State Output Leakage Current VIC Common Mode Voltage Range Vref Smoke Comparator Reference Voltage LED VDD - 3.08 VDD - 3.92 V * TA = 25C only. 4-26 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145010 Freescale Semiconductor, Inc... AC ELECTRICAL CHARACTERISTICS (Reference Timing Diagram Figures 3 and 4) (TA = 25C, VDD = 9.0 V, Component Values from Figure 5: R1 = 100.0 K, C3 = 1500.0 pF, R2 = 10.0 M) No. Symbol 1 1/fosc Oscillator Period* Free-Running Sawtooth Measured at Pin 12 2 tLED LED Pulse Period No Local Smoke, and No Remote Smoke Parameter Test Condition Clocks Min Max Unit 1 9.5 11.5 ms 4096 38.9 47.1 s 3 Remote Smoke, but No Local Smoke -- 4 Local Smoke or Pushbutton Test 64 0.60 0.74 1 9.5 11.5 ms s 5 tw(LED), tw(stb) 6 tIRED LED Pulse Width and Strobe Pulse Width IRED Pulse Period None Smoke Test 1024 9.67 11.83 7 Chamber Sensitivity Test, without Local Smoke 4096 38.9 47.1 8 Pushbutton Test 32 0.302 0.370 IRED Pulse Width Tf* 94 116 s -- -- 30 s 9 tw(IRED) 10 tr IRED Rise Time tf IRED Fall Time -- -- 200 11 tmod Silver and Brass Modulation Period Local or Remote Smoke -- 297 363 ms 11,12 ton/tmod Silver and Brass Duty Cycle Local or Remote Smoke -- 73 77 % 13 tCH Silver and Brass Chirp Pulse Period Low Supply or Degraded Chamber Sensitivity 4096 38.9 47.1 s 14 tw(CH) Silver and Brass Chirp Pulse Width Low Supply or Degraded Chamber Sensitivity 1 9.5 11.5 ms 15 tRR Rising Edge on I/O to Smoke Alarm Response Time Remote Smoke, No Local Smoke -- -- 800 ms 16 tstb Strobe Out Pulse Period Smoke Test 1024 9.67 11.83 s 17 Chamber Sensitivity Test, without Local Smoke 4096 38.9 47.1 18 Low Supply Test, without Local Smoke 4096 38.9 47.1 19 Pushbutton Test -- 0.302 0.370 * Oscillator period T (= Tr + Tf) is determined by the external components R1, R2, and C3 where Tr = (0.6931) R2 * C3 and Tf = (0.6931) R1 * C3. The other timing characteristics are some multiple of the oscillator timing as shown in the table. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-27 Freescale Semiconductor, Inc. AC PARAMETER (NORMALIZED TO 9.0 V VALUE) MC145010 1.04 1.02 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.98 TA = 25C 0.96 6.0 7.0 8.0 9.0 10.0 11.0 12.0 VDD, POWER SUPPLY VOLTAGE (V) AC PARAMETER (NORMALIZED TO 25 C VALUE) Freescale Semiconductor, Inc... Figure 1. AC Characteristics versus Supply 1.02 1.01 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.99 VDD = 9.0 V 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: Includes external component variations. See Figure 2B. Figure 2A. AC Characteristics versus Temperature Figure 2. COMPONENT VALUE (NORMALIZED TO 25 C VALUE) 1.03 1.02 1.01 10 M CARBON COMPOSITION 100 k METAL FILM 1.00 1500 pF DIPPED MICA 0.99 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: These components were used to generate Figure 2A. Figure 2B. RC Component Variation Over Temperature 4-28 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 16 6 17 NO LOW SUPPLY POWER-ON RESET CHAMBER SENSITIVITY OK 2 6 7 NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. SILVER, BRASS ENABLE (INTERNAL) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) SMOKE TEST (INTERNAL) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) OSC (PIN 12) 1 9 5 CHIRPS INDICATE LOW SUPPLY 13 18 Freescale Semiconductor, Inc... 14 CHIRPS INDICATE DEGRADED CHAMBER SENSITIVITY 13 Freescale Semiconductor, Inc. MC145010 Figure 3. Standby Timing Diagram 4-29 4-30 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 5 12 90% 10% LOCAL SMOKE (REMOTE SMOKE = DON'T CARE) 5 6 10 11 11 (AS OUTPUT) (NOT PERFORMED) (NOT PERFORMED) NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. NO SMOKE SILVER, BRASS ENABLE (INTERNAL) I/O (PIN 7) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) IRED 9 4 NO SMOKE 15 Freescale Semiconductor, Inc... REMOTE SMOKE (NO LOCAL SMOKE) (AS INPUT) 3 (NO PULSES) PUSHBUTTON TEST (AS OUTPUT) 4 19 8 MC145010 Freescale Semiconductor, Inc. Figure 4. Smoke Timing Diagram Motorola Sensor Device Data Freescale Semiconductor, Inc. C1 0.047 F + 1 TO 22 F C4** 9V B1 D1 REVERSE POLARITY PROTECTION CIRCUIT SW1 C2* 4700 pF 1 TEST 2 C2 LOW-SUPPLY TRIP R11 250 k R9 5k 3 R10 4.7 k Freescale Semiconductor, Inc... C1 PUSHBUTTON TEST 16 R6 100 k R14 560 R8 8.2 k D2 IR DETECTOR 4 DETECT VSS 15 R7 47 k 14 MC145010 STROBE R1 13 R1 100 k R12 1k C5 100 F MC145010 D3 IR EMITTER + 5 6 Q1 VDD OSC IRED LED 12 R2 10 M C3 1500 pF D4 VISIBLE LED R3 11 470 IR CURRENT R13* 4.7 TO 22 TO OTHER MC145010(s), ESCAPE LIGHT(S), AUXILIARY ALARM(S), REMOTE ALARM(S), AND/OR AUTO-DIALER 7 8 I/O BRASS FEEDBACK SILVER 10 R4 K 9 100 k 0.01 F C6 K HORN X1 2.2 M R5 K KValues for R4, R5, and C6 may differ depending on type of piezoelectric horn used. * C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown. R9 is for fine sensitivity adjustment (optional). If fixed resistors are used, R8 = 12 k, R10 is 5.6 k to 10 k, and R9 is eliminated. When R9 is used, noise pickup is increased due to antenna effects. Shielding may be required. **C4 should be 22 F if B1 is a carbon battery. C4 could be reduced to 1 F when an alkaline battery is used. Figure 5. Typical Battery-Powered Application PIN DESCRIPTIONS C1 (Pin 1) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier during pushbutton test and chamber sensitivity test (high gain). The capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. Av 1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000. C2 (Pin 2) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier except during pushbutton or chamber sensitivity tests. Av 1 + (C2/10) where C2 is in pF. This gain increases about 10% during the IRED pulse, after two consecutive local smoke detections. Motorola Sensor Device Data Resistor R14 must be installed in series with C2. R14 [1/(12C2)] - 680 where R14 is in ohms and C2 is in farads. DETECT (Pin 3) This input to the high-gain pulse amplifier is tied to the cathode of an external photodiode. The photodiode should have low capacitance and low dark leakage current. The diode must be shunted by a load resistor and is operated at zero bias. The Detect input must be ac/dc decoupled from all other signals, VDD, and VSS. Lead length and/or foil traces to this pin must be minimized, also. See Figure 6. STROBE (Pin 4) This output provides a strobed, regulated voltage referenced to VDD. The temperature coefficient of this voltage is 0.2%/C maximum from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. Strobe is tied to external resistor string R8, R9, and R10. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-31 MC145010 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... VDD (Pin 5) This pin is connected to the positive supply potential and may range from +6 to +12 V with respect to VSS. CAUTION: In battery-powered applications, reverse- polarity protection must be provided externally. IRED (Pin 6) This output provides pulsed base current for external NPN transistor Q1 used as the infrared emitter driver. Q1 must have 100. At 10 mA, the temperature coefficient of the output voltage is typically + 0.5%/C from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. The IRED pulse width (active-high) is determined by external components R1 and C3. With a 100 k/1500 pF combination, the nominal width is 105 s. To minimize noise impact, IRED is not active when the visible LED and horn outputs are active. IRED is active near the end of Strobe pulses for Smoke Tests, Chamber Sensitivity Test, and Pushbutton Test. I/O (Pin 7) This pin can be used to connect up to 40 units together in a wired-OR configuration for common signaling. VSS is used as the return. An on-chip current sink minimizes noise pick up during non-smoke conditions and eliminates the need for an external pull-down resistor to complete the wired-OR. Remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. I/O can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or auto-dialers. As an input, this pin feeds a positive-edge-triggered flip- flop whose output is sampled nominally every 625 ms during standby (using the recommended component values). A local-smoke condition or the pushbutton-test mode forces this current-limited output to source current. All input signals are ignored when I/O is sourcing current. I/O is disabled by the on-chip power-on reset to eliminate nuisance signaling during battery changes or system power-up. If unused, I/O must be left unconnected. BRASS (Pin 8) This half of the push-pull driver output is connected to the metal support electrode of a piezoelectric audio transducer and to the horn-starting resistor. A continuous modulated tone from the transducer is a smoke alarm indicating either local or remote smoke. A short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity. SILVER (Pin 9) This half of the push-pull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the horn-starting capacitor. FEEDBACK (Pin 10) This input is connected to both the feedback electrode of a self-resonating piezoelectric transducer and the horn-starting resistor and capacitor through current-limiting resistor R4. If unused, this pin must be tied to VSS or VDD. 4-32 LED (Pin 11) This active-low open-drain output directly drives an external visible LED at the pulse rates indicated below. The pulse width is equal to the OSC period. The load for the low-supply test is applied by this output. This low-supply test is non-coincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm signals. The LED also provides a visual indication of the detector status as follows, assuming the component values shown in Figure 5: Standby (includes low-supply and chamber sensitivity tests) -- Pulses every 43 seconds (nominal) Local Smoke -- Pulses every 0.67 seconds (nominal) Remote Smoke -- No pulses Pushbutton Test -- Pulses every 0.67 seconds (nominal) OSC (Pin 12) This pin is used in conjunction with external resistor R2 (10 M) to VDD and external capacitor C3 (1500 pF) to VDD to form an oscillator with a nominal period of 10.5 ms. R1 (Pin 13) This pin is used in conjunction with resistor R1 (100 k) to pin 12 and C3 (1500 pF, see pin 12 description) to determine the IRED pulse width. With this RC combination, the nominal pulse width is 105 s. VSS (Pin 14) This pin is the negative supply potential and the return for the I/O pin. Pin 14 is usually tied to ground. LOW-SUPPLY TRIP (Pin 15) This pin is connected to an external voltage which determines the low-supply alarm threshold. The trip voltage is obtained through a resistor divider connected between the VDD and LED pins. The low-supply alarm threshold voltage (in volts) (5R7/R6) + 5 where R6 and R7 are in the same units. TEST (Pin 16) This input has an on-chip pull-down device and is used to manually invoke a test mode. The Pushbutton Test mode is initiated by a high level at pin 16 (usually depression of a S.P.S.T. normally-open pushbutton switch to VDD). After one oscillator cycle, IRED pulses approximately every 336 ms, regardless of the presence of smoke. Additionally, the amplifier gain is increased by automatic selection of C1. Therefore, the background reflections in the smoke chamber may be interpreted as smoke, generating a simulated-smoke condition. After the second IRED pulse, a successful test activates the horn-driver and I/O circuits. The active I/O allows remote signaling for system testing. When the Pushbutton Test switch is released, the Test input returns to VSS due to the on-chip pull-down device. After one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulated-smoke condition. After two additional IRED pulses, less than a second, the IC exits the alarm mode and returns to standby timing. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145010 with 100 A continuously drawn out of the pin for at least one cycle on the OSC pin. To exit this mode, the Test pin is floated for at least one OSC cycle. In the calibration mode, the IRED pulse happens at every clock cycle and strobe is always on (active low). Also, Low Battery and supervisory tests are disabled in this mode. CALIBRATION To facilitate checking the sensitivity and calibrating smoke detectors, the MC145010 can be placed in a calibration mode. In this mode, certain device pins are controlled/reconfigured as shown in Table 1. To place the part in the calibration mode, pin 16 (Test) must be pulled below the VSS pin Table 1. Configuration of Pins in the Calibration Mode Description Comment 7 Disabled as an output. Forcing this pin high places the photo amp output on pin 1 or 2, as determined by Low-Supply Trip. The amp's output appears as pulses and is referenced to VDD. Low-Supply Trip 15 If the I/O pin is high, pin 15 controls which gain capacitor is used. Low: normal gain, amp output on pin 1. High: supervisory gain, amp output on pin 2. Feedback 10 Driving this input high enables hysteresis (10% gain increase) in the photo amp; pin 15 must be low. OSC 12 Driving this input high brings the internal clock high. Driving the input low brings the internal clock low. If desired, the RC network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. Silver 9 This pin becomes the smoke comparator output. When the OSC pin is toggling, positive pulses indicate that smoke has been detected. A static low level indicates no smoke. Brass 8 This pin becomes the smoke integrator output. That is, 2 consecutive smoke detections are required for "on" (static high level) and 2 consecutive no-detections for "off" (static low level). DO NOT RUN ANY ADDITIONAL TRACES IN THIS REGION C1 PIN 1 R14 C2 PIN 16 R11 R8 D2 MOUNTED IN CHAMBER PIN 9 R10 Freescale Semiconductor, Inc... Pin I/O PIN 8 NOTES: Illustration is bottom view of layout using a DIP. Top view for SOIC layout is mirror image. Optional potentiometer R9 is not included. Drawing is not to scale. Leads on D2, R11, R8, and R10 and their associated traces must be kept as short as possible. This practice minimizes noise pick up. Pin 3 must be decoupled from all other traces. Figure 6. Recommended PCB Layout Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-33 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Photoelectric Smoke Detector IC MC145011 with I/O Freescale Semiconductor, Inc... For Line-Powered Applications The CMOS MC145011 is an advanced smoke detector component containing sophisticated very-low-power analog and digital circuitry. The IC is used with an infrared photoelectric chamber. Detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. When detection occurs, a pulsating alarm is sounded via on-chip push-pull drivers and an external piezoelectric transducer. The variable-gain photo amplifier allows direct interface to IR detectors (photo-diodes). Two external capacitors C1 and C2, C1 being the larger, determine the gain settings. Low gain is selected by the IC during most of the standby state. Medium gain is selected during a local-smoke condition. High gain is used during pushbutton test. During standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain, also. The I/O pin, in combination with VSS, can be used to interconnect up to 40 units for common signaling. An on-chip current sink provides noise immunity when the I/O is an input. A local-smoke condition activates the short-circuit-protected I/O driver, thereby signaling remote smoke to the interconnected units. Additionally, the I/O pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate auto-dialers. While in standby, the low-supply detection circuitry conducts periodic checks using a load current from the LED pin. The trip point is set using two external resistors. The supply for the MC145011 must be a dc power source capable of supplying 35 mA continuously and 45 mA peak. When the MC145011 is in standby, an external LED is continuously illuminated to indicate that the device is receiving power. An extinguished LED accompanied by a pulsating audible alarm indicates a local-smoke condition. A pulsating audible alarm with the LED illuminated indicates a remote-smoke condition. A beep or chirp indicates a low-supply condition or degraded chamber sensitivity. A low-supply condition does not affect the smoke detection capability if VDD 6 V. Therefore, the low-supply condition and degraded chamber sensitivity can be distinguished by performing a pushbutton (chamber) test. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. 16 1 P SUFFIX PLASTIC DIP CASE 648-08 16 1 DW SUFFIX PLASTIC SOIC CASE 751G-03 ORDERING INFORMATION MC145011P PLASTIC DIP MC145011DW SOIC PACKAGE PIN ASSIGNMENT w * Operating Voltage Range: 6 to 12 V * Operating Temperature Range: C1 1 16 Test C2 2 15 Low-Supply Trip Detect 3 14 VSS Strobe 4 13 R1 VDD 5 12 Osc IRED 6 11 LED I/O 7 10 Feedback Brass 8 9 *10 to 60C * Average Standby Supply Current (Visible LED Illuminated): 20 mA * Power-On Reset Places IC in Standby Mode (Non-Alarm State) * Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins Silver * Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors REV 3 4-34 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145011 Block Diagram C1 C2 1 2 3 AMP OSC R1 TEST 12 GAIN ZERO VDD - 3.5 V REF - COMP + SMOKE GATE ON/OFF OSC TIMING LOGIC 13 16 GATE ON/OFF 7 ALARM LOGIC LOW SUPPLY DETECT HORN MODULATOR AND DRIVER 8 9 10 6 VDD - 5 V REF 11 Freescale Semiconductor, Inc... STROBE 4 - COMP + LOW-SUPPLY 15 TRIP I/O BRASS SILVER FEEDBACK IRED LED PIN 5 = VDD PIN 14 = VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Symbol VDD Parameter DC Supply Voltage Vin DC Input Voltage Iin DC Input Current, per Pin C1, C2, Detect Osc, Low-Supply Trip I/O Feedback Test Iout DC Output Current, per Pin IDD DC Supply Current, VDD and VSS Pins PD Power Dissipation in Still Air, Tstg Storage Temperature TL Value *0.5 to +12 *0.25 to VDD +0.25 *0.25 to VDD +0.25 *0.25 to VDD +10 *15 to +25 *1.0 to VDD +0.25 "10 "25 +25 / *150 5 Seconds Continuous Lead Temperature, 1 mm from Case for 10 Seconds 1200** 350*** Unit V V mA mA mA mW *55 to +125 C 260 C * Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the limits in the Electrical Characteristics tables. ** Derating: - 12 mW/C from 25 to 60C. *** Derating: - 3.5 mW/C from 25 to 60C. This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this high-impedance circuit. For proper operation, Vin and Vout should be constrained to the range VSS (Vin or Vout) VDD except for the I/O, which can exceed VDD, and the Test input, which can go below VSS. Unused inputs must always be tied to an appropriate logic voltage level (e.g., either VSS or VDD). Unused outputs and/or an unused I/O must be left open. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-35 Freescale Semiconductor, Inc. MC145011 ELECTRICAL CHARACTERISTICS (TA = - 10 to 60C Unless Otherwise Indicated, Voltages Referenced to VSS) Freescale Semiconductor, Inc... Symbol Parameter Test Condition VDD V Min Max Unit -- 6.0 12 V -- 6.5 7.8 V VDD Power Supply Voltage Range VTH Supply Threshold Voltage, Low-Supply Alarm Low-Supply Trip: Vin = VDD/3 IDD Average Operating Supply Current, Excluding the Visible LED Current (per Package) Standby Configured per Figure 5 12.0 -- 12 A iDD Peak Supply Current , Excluding the Visible LED Current (per Package) During Strobe On, IRED Off Configured per Figure 5 12.0 -- 2.0 mA During Strobe On, IRED On Configured per Figure 5 12.0 -- 3.0 VIL Low-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 -- -- -- 1.5 2.7 7.0 V VIH High-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 3.2 6.3 8.5 -- -- -- V Vin = VSS or VDD Vin = VSS or VDD Vin = VSS or VDD 12.0 12.0 12.0 -- -- -- 100 100 100 nA Iin Input Current Osc, Detect Low-Supply Trip Feedback IIL Low-Level Input Current Test Vin = VSS 12.0 -- -1 A IIH Pull-Down Current Test I/O Vin = VDD No Local Smoke, Vin = VDD No Local Smoke, Vin = 17 V 9.0 9.0 12.0 0.5 25 -- 10 100 140 A VOL Low-Level Output Voltage LED Silver, Brass Iout = 10 mA Iout = 16 mA 6.5 6.5 -- -- 0.6 1.0 V VOH High-Level Output Voltage Silver, Brass Iout = - 16 mA 6.5 5.5 -- V Vout Output Voltage (For Line Regulation, see Pin Descriptions) Inactive, Iout = -1 A Active, Iout = 100 A to 500 A (Load Regulation) -- 9.0 VDD - 0.1 VDD - 4.4 -- VDD - 5.6 V Inactive, Iout = 1 A Active, Iout = 6 mA (Load Regulation) -- 9.0 -- 2.25* 0.1 3.75* Local Smoke, Vout = 4.5 V 6.5 -4 -- Local Smoke, Vout = VSS (Short Circuit Current) 12.0 -- - 16 Vout = VSS or VDD 12.0 -- 1 A VDD - 4 VDD - 2 V Strobe IRED IOH High-Level Output Current I/O IOZ Off-State Output Leakage Current VIC Common Mode Voltage Range Vref Smoke Comparator Reference Voltage LED C1, C2, Detect Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- Internal Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- VDD - 3.08 VDD - 3.92 mA V * TA = 25C only. 4-36 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145011 Freescale Semiconductor, Inc... AC ELECTRICAL CHARACTERISTICS (Reference Timing Diagram Figures 3 and 4) (TA = 25C, VDD = 9.0 V, Component Values from Figure 5: R1 = 100.0 K, C3 = 1500.0 pF, R2 = 10.0 M) No. Symbol 1 1/fosc Oscillator Period* Free-Running Sawtooth Measured at Pin 12 2 tLED LED Status No Local Smoke, and No Remote Smoke Illuminated 3 Remote Smoke, but No Local Smoke Illuminated 4 Local Smoke or Pushbutton Test Parameter 5 tw(stb) Strobe Pulse Width 6 tIRED IRED Pulse Period Test Condition Min Max Unit 9.5 11.5 ms Extinguished 9.5 11.5 ms s Smoke Test 9.67 11.83 7 Chamber Sensitivity Test, without Local Smoke 38.9 47.1 8 Pushbutton Test 0.302 0.370 IRED Pulse Width 94 116 s -- 30 s 9 tw(IRED) 10 tr IRED Rise Time tf IRED Fall Time 11 tmod 11, 12 ton/tmod 13 -- 200 Silver and Brass Modulation Period Local or Remote Smoke 297 363 ms Silver and Brass Duty Cycle Local or Remote Smoke 73 77 % tCH Silver and Brass Chirp Pulse Period Low Supply or Degraded Chamber Sensitivity 38.9 47.1 s 14 tw(CH) Silver and Brass Chirp Pulse Width Low Supply or Degraded Chamber Sensitivity 9.5 11.5 ms 15 tRR Rising Edge on I/O to Smoke Alarm Response Time Remote Smoke, No Local Smoke -- 800 ms 16 tstb Strobe Pulse Period s Smoke Test 9.67 11.83 17 Chamber Sensitivity Test, without Local Smoke 38.9 47.1 18 Low Supply Test, without Local Smoke 38.9 47.1 19 Pushbutton Test 0.302 0.370 * Oscillator period T (= Tr + Tf) is determined by the external components R1, R2, and C3 where Tr = (0.6931) R2 C3 and Tf = (0.6931) R1 C3. The other timing characteristics are some multiple of the oscillator timing as shown in the table. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-37 Freescale Semiconductor, Inc. AC PARAMETER (NORMALIZED TO 9.0 V VALUE) MC145011 1.04 1.02 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.98 TA = 25C 0.96 6.0 7.0 8.0 9.0 10.0 11.0 12.0 VDD, POWER SUPPLY VOLTAGE (V) AC PARAMETER (NORMALIZED TO 25 C VALUE) Freescale Semiconductor, Inc... Figure 1. AC Characteristics versus Supply 1.02 1.01 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.99 VDD = 9.0 V 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: Includes external component variations. See Figure 2B. Figure 2A. AC Characteristics versus Temperature Figure 2. COMPONENT VALUE (NORMALIZED TO 25 C VALUE) 1.03 1.02 10 M CARBON COMPOSITION 1.01 100 k METAL FILM 1.00 1500 pF DIPPED MICA 0.99 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: These components were used to generate Figure 2A. Figure 2B. RC Component Variation Over Temperature 4-38 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 16 6 17 9 NO LOW SUPPLY -- CHAMBER SENSITIVITY OK POWER-ON RESET 2 (CONTINUOUSLY ILLUMINATED) 6 7 NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. SILVER, BRASS ENABLE (INTERNAL) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) SMOKE TEST (INTERNAL) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) OSC (PIN 12) 1 CHIRPS INDICATE LOW SUPPLY 13 18 Freescale Semiconductor, Inc... 14 CHIRPS INDICATE DEGRADED CHAMBER SENSITIVITY 13 Freescale Semiconductor, Inc. MC145011 Figure 3. Standby Timing Diagram 4-39 4-40 Figure 4. Smoke Timing Diagram For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 12 90% 10% LOCAL SMOKE (REMOTE SMOKE = DON'T CARE) 4 (EXTINGUISHED) 5 6 10 11 10 NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. NO SMOKE SILVER, BRASS ENABLE (INTERNAL) I/O (PIN 7) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) IRED 9 (AS OUTPUT) (NOT PERFORMED) (NOT PERFORMED) NO SMOKE 15 REMOTE SMOKE (NO LOCAL SMOKE) (AS INPUT) 3 (CONTINUOUSLY ILLUMINATED) Freescale Semiconductor, Inc... PUSHBUTTON TEST (AS OUTPUT) 4 19 8 MC145011 Freescale Semiconductor, Inc. Motorola Sensor Device Data Freescale Semiconductor, Inc. C1 0.047 F 1 C1 TEST 2 C2 LOW-SUPPLY TRIP R11 250 k R9 5k 3 R10 4.7 k Freescale Semiconductor, Inc... SW1 PUSHBUTTON TEST 16 R6 100 k R14 560 R8 8.2 k D1 IR DETECTOR 4 DETECT VSS 15 R7 47 k 14 MC145011 STROBE R1 13 R1 100 k R12 1k C5 100 F + 1 TO 22 F C4** C2* 4700 pF V+ MC145011 D2 IR EMITTER + 5 6 Q1 VDD OSC IRED LED 12 R2 10 M C3 1500 pF D3 VISIBLE LED R3 11 470 IR CURRENT R13* 4.7 TO 22 TO OTHER MC145011(s), ESCAPE LIGHT(S), AUXILIARY ALARM(S), REMOTE ALARM(S), AND/OR AUTO-DIALER 7 8 I/O BRASS FEEDBACK SILVER 10 R4 9 100 k 0.01 F C6 HORN X1 2.2 M R5 Values for R4, R5, and C6 may differ depending on type of piezoelectric horn used. * C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown. R9 is for fine sensitivity adjustment (optional). If fixed resistors are used, R8 = 12 k, R10 is 5.6 k to 10 k, and R9 is eliminated. When R9 is used, noise pickup is increased due to antenna effects. Shielding may be required. ** C4 should be 22 F if supply line resistance is high (up to 50 ). C4 could be reduced to 1 F when supply line resistance is < 30 . Figure 5. Typical Application PIN DESCRIPTIONS Resistor R14 must be installed in series with C2. R14 [1/(12C2)] - 680 where R14 is in ohms and C2 is in farads. C1 (Pin 1) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier during pushbutton test and chamber sensitivity test (high gain). The capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. Av 1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000. DETECT (Pin 3) This input to the high-gain pulse amplifier is tied to the cathode of an external photodiode. The photodiode should have low capacitance and low dark leakage current. The diode must be shunted by a load resistor and is operated at zero bias. The Detect input must be ac/dc decoupled from all other signals, VDD, and VSS. Lead length and/or foil traces to this pin must be minimized, also. See Figure 6. C2 (Pin 2) STROBE (Pin 4) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier except during pushbutton or chamber sensitivity tests. Av 1 + (C2/10) where C2 is in pF. This gain increases about 10% during the IRED pulse, after two consecutive local smoke detections. This output provides a strobed, regulated voltage referenced to VDD. The temperature coefficient of this voltage is 0.2%/C maximum from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. Strobe is tied to external resistor string R8, R9, and R10. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-41 MC145011 Freescale Semiconductor, Inc. VDD (Pin 5) LED (Pin 11) This pin is connected to the positive supply potential and may range from + 6 to + 12 V with respect to VSS. This active-low open-drain output directly drives an external visible LED. The load for the low-supply test is applied by this output. This low-supply test is non-coincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm signals. The LED also provides a visual indication of the detector status as follows, assuming the component values shown in Figure 5: IRED (Pin 6) Freescale Semiconductor, Inc... This output provides pulsed base current for external NPN transistor Q1 used as the infrared emitter driver. Q1 must have 100. At 10 mA, the temperature coefficient of the output voltage is typically + 0.5%/C from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. The IRED pulse width (active-high) is determined by external components R1 and C3. With a 100 k/1500 pF combination, the nominal width is 105 s. To minimize noise impact, IRED is not active when the visible LED and horn outputs are active. IRED is active near the end of Strobe pulses for Smoke Tests, Chamber Sensitivity Test, and Pushbutton Test. Standby (includes low-supply and chamber sensitivity tests) -- constantly illuminated Local Smoke -- constantly extinguished Remote Smoke -- constantly illuminated Pushbutton Test -- constantly extinguished (system OK); constantly illuminated (system problem) OSC (Pin 12) I/O (Pin 7) This pin can be used to connect up to 40 units together in a wired-OR configuration for common signaling. VSS is used as the return. An on-chip current sink minimizes noise pick up during non-smoke conditions and eliminates the need for an external pull-down resistor to complete the wired-OR. Remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. I/O can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or auto-dialers. As an input, this pin feeds a positive-edge-triggered flip- flop whose output is sampled nominally every 625 ms during standby (using the recommended component values). A local-smoke condition or the pushbutton-test mode forces this current-limited output to source current. All input signals are ignored when I/O is sourcing current. I/O is disabled by the on-chip power-on reset to eliminate nuisance signaling during battery changes or system power-up. If unused, I/O must be left unconnected. BRASS (Pin 8) This half of the push-pull driver output is connected to the metal support electrode of a piezoelectric audio transducer and to the horn-starting resistor. A continuous modulated tone from the transducer is a smoke alarm indicating either local or remote smoke. A short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity. SILVER (Pin 9) This half of the push-pull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the horn-starting capacitor. FEEDBACK (Pin 10) This input is connected to both the feedback electrode of a self-resonating piezoelectric transducer and the horn-starting resistor and capacitor through current-limiting resistor R4. If unused, this pin must be tied to VSS or VDD. 4-42 This pin is used in conjunction with external resistor R2 (10 M) to VDD and external capacitor C3 (1500 pF) to VDD to form an oscillator with a nominal period of 10.5 ms. R1 (Pin 13) This pin is used in conjunction with resistor R1 (100 k) to pin 12 and C3 (1500 pF, see pin 12 description) to determine the IRED pulse width. With this RC combination, the nominal pulse width is 105 s. VSS (Pin 14) This pin is the negative supply potential and the return for the I/O pin. Pin 14 is usually tied to ground. LOW-SUPPLY TRIP (Pin 15) This pin is connected to an external voltage which determines the low-supply alarm threshold. The trip voltage is obtained through a resistor divider connected between the VDD and LED pins. The low-supply alarm threshold voltage (in volts) (5R7/R6) + 5 where R6 and R7 are in the same units. TEST (Pin 16) This input has an on-chip pull-down device and is used to manually invoke a test mode. The Pushbutton Test mode is initiated by a high level at pin 16 (usually depression of a S.P.S.T. normally-open pushbutton switch to VDD). After one oscillator cycle, IRED pulses approximately every 336 ms, regardless of the presence of smoke. Additionally, the amplifier gain is increased by automatic selection of C1. Therefore, the background reflections in the smoke chamber may be interpreted as smoke, generating a simulated-smoke condition. After the second IRED pulse, a successful test activates the horn-driver and I/O circuits. The active I/O allows remote signaling for system testing. When the Pushbutton Test switch is released, the Test input returns to VSS due to the on-chip pull-down device. After one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulated-smoke condition. After two additional IRED pulses, less than a second, the IC exits the alarm mode and returns to standby timing. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145011 tion mode, Pin 16 (Test) must be pulled below the VSS pin with 100 A continuously drawn out of the pin for at least one cycle on the OSC pin. To exit this mode, the Test pin is floated for at least one OSC cycle. In the calibration mode, the IRED pulse rate is increased to one for every OSC cycle. Also, Strobe is always active low. CALIBRATION To facilitate checking the sensitivity and calibrating smoke detectors, the MC145011 can be placed in a calibration mode. In this mode, certain device pins are controlled/reconfigured as shown in Table 1. To place the part in the calibra- Table 1. Configuration of Pins in the Calibration Mode Pin Comment I/O 7 Disabled as an output. Forcing this pin high places the photo amp output on pin 1 or 2, as determined by Low-Supply Trip. The amp's output appears as pulses and is referenced to VDD. Low-Supply Trip 15 If the I/O pin is high, pin 15 controls which gain capacitor is used. Low: normal gain, amp output on pin 1. High: supervisory gain, amp output on pin 2. Feedback 10 Driving this input high enables hysteresis (10% gain increase) in the photo amp; pin 15 must be low. Osc 12 Driving this input high brings the internal clock high. Driving the input low brings the internal clock low. If desired, the RC network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. Silver 9 This pin becomes the smoke comparator output. When the OSC pin is toggling, positive pulses indicate that smoke has been detected. A static low level indicates no smoke. Brass 8 This pin becomes the smoke integrator output. That is, 2 consecutive smoke detections are required for "on" (static high level) and 2 consecutive no-detections for "off" (static low level). DO NOT RUN ANY ADDITIONAL TRACES IN THIS REGION C1 PIN 1 R14 C2 PIN 16 R11 R8 D1 MOUNTED IN CHAMBER PIN 9 R10 Freescale Semiconductor, Inc... Description PIN 8 NOTES: Illustration is bottom view of layout using a DIP. Top view for SOIC layout is mirror image. Optional potentiometer R9 is not included. Drawing is not to scale. Leads on D1, R11, R8, and R10 and their associated traces must be kept as short as possible. This practice minimizes noise pick up. Pin 3 must be decoupled from all other traces. Figure 6. Recommended PCB Layout Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-43 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Photoelectric Smoke MC145012 Detector IC with I/O and Freescale Semiconductor, Inc... Temporal Pattern Horn Driver The CMOS MC145012 is an advanced smoke detector component containing sophisticated very-low-power analog and digital circuitry. The IC is used with an infrared photoelectric chamber. Detection is accomplished by sensing scattered light from minute smoke particles or other aerosols. When detection occurs, a pulsating alarm is sounded via on-chip push-pull drivers and an external piezoelectric transducer. The variable-gain photo amplifier allows direct interface to IR detectors (photodiodes). Two external capacitors, C1 and C2, C1 being the larger, determine the gain settings. Low gain is selected by the IC during most of the standby state. Medium gain is selected during a local-smoke condition. High gain is used during pushbutton test. During standby, the special monitor circuit which periodically checks for degraded chamber sensitivity uses high gain also. The I/O pin, in combination with VSS, can be used to interconnect up to 40 units for common signaling. An on-chip current sink provides noise immunity when the I/O is an input. A local-smoke condition activates the short-circuit- protected I/O driver, thereby signaling remote smoke to the interconnected units. Additionally, the I/O pin can be used to activate escape lights, enable auxiliary or remote alarms, and/or initiate auto-dialers. While in standby, the low-supply detection circuitry conducts periodic checks using a pulsed load current from the LED pin. The trip point is set using two external resistors. The supply for the MC145012 can be a 9 V battery. A visible LED flash accompanying a pulsating audible alarm indicates a local-smoke condition. A pulsating audible alarm with no LED flash indicates a remote-smoke condition. A beep or chirp occurring virtually simultaneously with an LED flash indicates a low-supply condition. A beep or chirp occurring halfway between LED flashes indicates degraded chamber sensitivity. A low-supply condition does not affect the smoke detection capability if VDD 6 V. Therefore, the low-supply condition and degraded chamber sensitivity can be further distinguished by performing a pushbutton (chamber) test. 16 1 P SUFFIX PLASTIC DIP CASE 648-08 16 1 DW SUFFIX SOIC PACKAGE CASE 751G-03 ORDERING INFORMATION MC145012P PLASTIC DIP MC145012DW SOIC PACKAGE PIN ASSIGNMENT C1 1 16 Test 15 Low-Supply Trip * Circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 Specifications C2 2 Detect 3 14 VSS * Operating Voltage Range: 6 to 12 V Strobe 4 13 R1 VDD 5 12 Osc IRED 6 11 LED I/O 7 10 Feedback Brass 8 9 * Operating Temperature Range: - 10 to 60C * Average Supply Current: 8 A * I/O Pin Allows Units to be Interconnected for Common Signalling * Power-On Reset Places IC in Standby Mode (Non-Alarm State) * Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins Silver * Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors * Supports NFPA 72, ANSI S3.41, and ISO 8201 Audible Emergency Evacuation Signals * Ideal for battery-powered applications REV 4 4-44 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145012 BLOCK DIAGRAM C1 C2 1 2 3 AMP OSC R1 TEST 12 GAIN ZERO VDD - 3.5 V REF - COMP + SMOKE GATE ON/OFF OSC TIMING LOGIC 13 16 GATE ON/OFF 7 ALARM LOGIC LOW SUPPLY DETECT TEMPORAL PATTERN HORN MODULATOR AND DRIVER 8 9 10 6 VDD - 5 V REF 11 Freescale Semiconductor, Inc... STROBE 4 - COMP + LOW-SUPPLY 15 TRIP I/O BRASS SILVER FEEDBACK IRED LED PIN 5 = VDD PIN 14 = VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Symbol VDD Parameter *0.5 to +12 DC Supply Voltage Vin DC Input Voltage Iin DC Input Current, per Pin C1, C2, Detect Osc, Low-Supply Trip I/O Feedback Test Iout DC Output Current, per Pin IDD DC Supply Current, VDD and VSS Pins PD Power Dissipation in Still Air, Tstg Storage Temperature TL Value *0.25 to VDD +0.25 *0.25 to VDD +0.25 *0.25 to VDD +10 *15 to +25 *1.0 to VDD +0.25 "10 "25 +25 / *150 5 Seconds Continuous Lead Temperature, 1 mm from Case for 10 Seconds 1200** 350*** Unit V V mA mA mA mW *55 to +125 C 260 C * Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the limits in the Electrical Characteristics tables. ** Derating: - 12 mW/C from 25 to 60C. *** Derating: - 3.5 mW/C from 25 to 60C. This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must be taken to avoid applications of any voltage higher than maximum rated voltages to this high-impedance circuit. For proper operation, Vin and Vout should be constrained to the range VSS (Vin or Vout) VDD except for the I/O, which can exceed VDD, and the Test input, which can go below VSS. Unused inputs must always be tied to an appropriate logic voltage level (e.g., either VSS or VDD). Unused outputs and/or an unused I/O must be left open. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-45 Freescale Semiconductor, Inc. MC145012 ELECTRICAL CHARACTERISTICS (Voltages Referenced to VSS, TA = - 10 to 60C Unless Otherwise Indicated) Freescale Semiconductor, Inc... Symbol Parameter Test Condition VDD V Min Max Unit -- 6 12 V -- 6.5 7.8 V VDD Power Supply Voltage Range VTH Supply Threshold Voltage, Low-Supply Alarm Low-Supply Trip: Vin = VDD/3 IDD Average Operating Supply Current (per Package) (Does Not Include Current through D3-IR Emitter) Standby Configured per Figure 5 12.0 -- 8.0 A iDD Peak Supply Current (per Package) (Does Not Include IRED Current into Base of Q1) During Strobe On, IRED Off Configured per Figure 5 12.0 -- 2.0 mA During Strobe On, IRED On Configured per Figure 5 12.0 -- 3.0 VIL Low-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 -- -- -- 1.5 2.7 7.0 V VIH High-Level Input Voltage I/O Feedback Test 9.0 9.0 9.0 3.2 6.3 8.5 -- -- -- V Vin = VSS or VDD Vin = VSS or VDD Vin = VSS or VDD 12.0 12.0 12.0 -- -- -- 100 100 100 nA Iin Input Current OSC, Detect Low-Supply Trip Feedback IIL Low-Level Input Current Test Vin = VSS 12.0 - 100 -1 A IIH Pull-Down Current Test I/O Vin = VDD No Local Smoke, Vin = VDD No Local Smoke, Vin = 17 V 9.0 9.0 12.0 0.5 25 -- 10 100 140 A VOL Low-Level Output Voltage LED Silver, Brass Iout = 10 mA Iout = 16 mA 6.5 6.5 -- -- 0.6 1.0 V VOH High-Level Output Voltage Silver, Brass Iout = - 16 mA 6.5 5.5 -- V Vout Output Voltage (For Line Regulation, See Pin Descriptions) Inactive, Iout = 1 A Active, Iout = 100 A to 500 A (Load Regulation) -- 9.0 VDD - 0.1 VDD - 4.4 -- VDD - 5.6 V Inactive, Iout = 1 A Active, Iout = 6 mA (Load Regulation) -- 9.0 -- 2.25* 0.1 3.75* Local Smoke, Vout = 4.5 V 6.5 -4 -- Local Smoke, Vout = VSS (Short Circuit Current) 12.0 -- - 16 Vout = VSS or VDD 12.0 -- 1 A VDD - 4 VDD - 2 V Strobe IRED IOH High-Level Output Current I/O IOZ Off-State Output Leakage Current VIC Common Mode Voltage Range Vref Smoke Comparator Reference Voltage LED C1, C2, Detect Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- Internal Local Smoke, Pushbutton Test, or Chamber Sensitivity Test -- VDD - 3.08 VDD - 3.92 mA V * TA = 25C only. 4-46 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145012 Freescale Semiconductor, Inc... AC ELECTRICAL CHARACTERISTICS (Reference Timing Diagram Figures 3 and 4) (TA = 25C, VDD = 9.0 V, Component Values from Figure 5: R1 = 100.0 K, C3 = 1500.0 pF, R2 = 7.5 M) No. Symbol 1 1/fosc Oscillator Period Free-Running Sawtooth Measured at Pin 12 2 tLED LED Pulse Period No Local Smoke, and No Remote Smoke Parameter Test Condition Clocks Min* Typ** Max* Unit 1 7.0 7.9 8.6 ms 4096 28.8 32.4 35.2 s 3 Remote Smoke, but No Local Smoke -- 4 Local Smoke 64 0.45 0.5 0.55 5 Pushbutton Test 64 0.45 0.5 0.55 1 7.0 -- 8.6 ms LED Pulse Width and Strobe Pulse Width Extinguished 6 tw(LED), tw(stb) 7 tIRED IRED Pulse Period Smoke Test 1024 7.2 8.1 8.8 s 8 tIRED IRED Pulse Period Chamber Sensitivity Test, without Local Smoke 4096 28.8 32.4 35.2 s Pushbutton Test 128 0.9 1 1.1 IRED Pulse Width Tf* 94 9 10 tw(IRED) 116 s s 11 tr IRED Rise Time -- -- 30 12 tf IRED Fall Time -- -- 200 13 ton 64 0.45 0.5 0.55 14 toff Silver and Brass Temporal M d l ti P Modulation Pulse l Width 0.45 0.5 0.55 15 toffd 192 1.35 1.52 1.65 16 tCH Silver and Brass Chirp Pulse Period 4096 28.8 32.4 35.2 s 17 twCH Silver and Brass Chirp Pulse Width 1 7.0 7.9 8.6 ms 18 tRR Rising Edge on I/O to Smoke Alarm Response Time Remote Smoke, No Local Smoke -- -- 2! -- s 19 tstb Strobe Out Pulse Period Smoke Test 1024 7.2 8.1 8.8 s 20 Chamber Sensitivity Test, without Local Smoke 4096 28.8 32.4 35.2 21 Low Supply Test, without Local Smoke 4096 28.8 32.4 35.2 22 Pushbutton Test -- -- 1 -- Low Supply or Degraded Chamber Sensitivity s * Oscillator period T (= Tr + Tf) is determined by the external components R1, R2, and C3 where Tr = (0.6931) R2 * C3 and Tf = (0.6931) R1 * C3. The other timing characteristics are some multiple of the oscillator timing as shown in the table. The timing shown should accomodate the NFPA 72, ANSI S3.41, and ISO 8201 audible emergency evacuation signals. ** Typicals are not guaranteed. ! Time is typical -- depends on what point in cycle signal is applied. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-47 Freescale Semiconductor, Inc. AC PARAMETER (NORMALIZED TO 9.0 V VALUE) MC145012 1.04 1.02 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.98 TA = 25C 0.96 6.0 7.0 8.0 9.0 10.0 11.0 12.0 VDD, POWER SUPPLY VOLTAGE (V) AC PARAMETER (NORMALIZED TO 25 C VALUE) Freescale Semiconductor, Inc... Figure 1. AC Characteristics versus Supply 1.02 1.01 PULSE WIDTH OF IRED 1.00 PERIOD OR PULSE WIDTH OF OTHER PARAMETERS 0.99 VDD = 9.0 V 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: Includes external component variations. See Figure 2B. Figure 2A. AC Characteristics versus Temperature Figure 2. COMPONENT VALUE (NORMALIZED TO 25 C VALUE) 1.03 1.02 1.01 7.5 M CARBON COMPOSITION 100 k METAL FILM 1.00 1500 pF DIPPED MICA 0.99 0.98 - 10 0 10 20 30 40 50 60 TA, AMBIENT TEMPERATURE (C) NOTE: These components were used to generate Figure 2A. Figure 2B. RC Component Variation Over Temperature 4-48 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 19 7 7 20 8 NO LOW SUPPLY -- CHAMBER SENSITIVITY OK POWER-ON RESET 2 21 NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. SILVER, BRASS ENABLE (INTERNAL) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) PHOTO SAMPLE (INTERNAL) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) OSC (PIN 12) 1 6 CHIRPS INDICATE LOW SUPPLY 16 21 Freescale Semiconductor, Inc... 17 CHIRPS INDICATE DEGRADED CHAMBER SENSITIVITY 16 Freescale Semiconductor, Inc. MC145012 Figure 3. Typical Standby Timing 4-49 4-50 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com 6 6 14 90% 10% 13 4 15 (AS OUTPUT) (NOT PERFORMED) (NOT PERFORMED) 12 LOCAL SMOKE (REMOTE SMOKE = DON'T CARE) 18 7 11 NOTES: Numbers refer to the AC Electrical Characteristics Table. Illustration is not to scale. NO SMOKE SILVER, BRASS ENABLE (INTERNAL) I/O (PIN 7) LED (PIN 11) STROBE (PIN 4) IRED (PIN 6) CHAMBER TEST (INTERNAL) LOW SUPPLY TEST (INTERNAL) IRED 10 NO SMOKE 18 REMOTE SMOKE (NO LOCAL SMOKE) (AS INPUT) 3 (NO PULSES) Freescale Semiconductor, Inc... 22 9 PUSHBUTTON TEST (AS OUTPUT) 5 MC145012 Freescale Semiconductor, Inc. Figure 4. Typical Local Smoke Timing Motorola Sensor Device Data Freescale Semiconductor, Inc. C1 0.047 F + 1 TO 22 F C4** 9V B1 D1 MC145012 REVERSE POLARITY PROTECTION CIRCUIT SW1 C2* 4700 pF 1 2 C2 LOW-SUPPLY TRIP R11 250 k R9 5k 3 R10 4.7 k Freescale Semiconductor, Inc... TEST R6 100 k R14 560 R8 8.2 k D2 IR DETECTOR 4 DETECT VSS 15 R7 47 k 14 MC145012 STROBE R1 13 R1 100 k R12 1k C5 100 F C1 PUSHBUTTON TEST 16 D3 IR EMITTER + 5 6 Q1 VDD OSC IRED LED 12 R2 7.5 M C3 1500 pF D4 VISIBLE LED R3 11 470 IR CURRENT R13* 4.7 TO 22 TO OTHER MC145012(s), ESCAPE LIGHT(S), AUXILIARY ALARM(S), REMOTE ALARM(S), AND/OR AUTO-DIALER 7 8 I/O BRASS FEEDBACK SILVER 10 R4# 9 100 k 0.01 F C6# HORN X1 2.2 M R5# # Values for R4, R5, and C6 may differ depending on type of piezoelectric horn used. * C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown. R9 is for fine sensitivity adjustment (optional). If fixed resistors are used, R8 = 12 k, R10 is 5.6 k to 10 k, and R9 is eliminated. When R9 is used, noise pickup is increased due to antenna effects. Shielding may be required. **C4 should be 22 F if B1 is a carbon battery. C4 could be reduced to 1 F when an alkaline battery is used. Figure 5. Typical Battery-Powered Application PIN DESCRIPTIONS C1 (Pin 1) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier during pushbutton test and chamber sensitivity test (high gain). The capacitor value is chosen such that the alarm is tripped from background reflections in the chamber during pushbutton test. Av 1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000. C2 (Pin 2) A capacitor connected to this pin as shown in Figure 5 determines the gain of the on-chip photo amplifier except during pushbutton or chamber sensitivity tests. Av 1 + (C2/10) where C2 is in pF. This gain increases about 10% during the IRED pulse, after two consecutive local smoke detections. Motorola Sensor Device Data Resistor R14 must be installed in series with C2. R14 [1/(12C2)] - 680 where R14 is in ohms and C2 is in farads. DETECT (Pin 3) This input to the high-gain pulse amplifier is tied to the cathode of an external photodiode. The photodiode should have low capacitance and low dark leakage current. The diode must be shunted by a load resistor and is operated at zero bias. The Detect input must be ac/dc decoupled from all other signals, VDD, and VSS. Lead length and/or foil traces to this pin must be minimized, also. See Figure 6. STROBE (Pin 4) This output provides a strobed, regulated voltage referenced to VDD. The temperature coefficient of this voltage is 0.2%/C maximum from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. Strobe is tied to external resistor string R8, R9, and R10. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-51 MC145012 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... VDD (Pin 5) This pin is connected to the positive supply potential and may range from + 6 to + 12 V with respect to V SS CAUTION: In battery-powered applications, reverse-polarity protection must be provided externally. IRED (Pin 6) This output provides pulsed base current for external NPN transistor Q1 used as the infrared emitter driver. Q1 must have 100. At 10 mA, the temperature coefficient of the output voltage is typically + 0.5%/C from - 10 to 60C. The supply-voltage coefficient (line regulation) is 0.2%/V maximum from 6 to 12 V. The IRED pulse width (active-high) is determined by external components R1 and C3. With a 100 k/1500 pF combination, the nominal width is 105 s. To minimize noise impact, IRED is not active when the visible LED and horn outputs are active. IRED is active near the end of strobe pulses for smoke tests, chamber sensitivity test, and pushbutton test. I/O (Pin 7) This pin can be used to connect up to 40 units together in a wired-OR configuration for common signaling. VSS is used as the return. An on-chip current sink minimizes noise pick up during non-smoke conditions and eliminates the need for an external pull-down resistor to complete the wired-OR. Remote units at lower supply voltages do not draw excessive current from a sending unit at a higher supply voltage. I/O can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or auto-dialers. As an input, this pin feeds a positive-edge-triggered flip- flop whose output is sampled nominally every 1 second during standby (using the recommended component values). A local-smoke condition or the pushbutton-test mode forces this current-limited output to source current. All input signals are ignored when I/O is sourcing current. I/O is disabled by the on-chip power-on reset to eliminate nuisance signaling during battery changes or system power- up. If unused, I/O must be left unconnected. BRASS (Pin 8) This half of the push-pull driver output is connected to the metal support electrode of a piezoelectric audio transducer and to the horn-starting resistor. A continuous modulated tone from the transducer is a smoke alarm indicating either local or remote smoke. A short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity. SILVER (Pin 9) This half of the push-pull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the horn-starting capacitor. FEEDBACK (Pin 10) This input is connected to both the feedback electrode of a self-resonating piezoelectric transducer and the horn-starting resistor and capacitor through current-limiting resistor R4. If unused, this pin must be tied to VSS or VDD. 4-52 LED (Pin 11) This active-low open-drain output directly drives an external visible LED at the pulse rates indicated below. The pulse width is equal to the OSC period. The load for the low-supply test is applied by this output. This low-supply test is non-coincident with the smoke tests, chamber sensitivity test, pushbutton test, or any alarm signals. The LED also provides a visual indication of the detector status as follows, assuming the component values shown in Figure 5: Standby (includes low-supply and chamber sensitivity tests) -- Pulses every 32.4 seconds (typical) Local Smoke -- Pulses every 0.51 seconds (typical) Remote Smoke -- No pulses Pushbutton Test -- Pulses every 0.51 seconds (typical) OSC (Pin 12) This pin is used in conjunction with external resistor R2 (7.5 M) to VDD and external capacitor C3 (1500 pF) to VDD to form an oscillator with a nominal period of 7.9 ms (typical). R1 (Pin 13) This pin is used in conjunction with resistor R1 (100 k) to Pin 12 and C3 (1500 pF, see Pin 12 description) to determine the IRED pulse width. With this RC combination, the nominal pulse width is 105 s. VSS (Pin 14) This pin is the negative supply potential and the return for the I/O pin. Pin 14 is usually tied to ground. LOW-SUPPLY TRIP (Pin 15) This pin is connected to an external voltage which determines the low-supply alarm threshold. The trip voltage is obtained through a resistor divider connected between the VDD and LED pins. The low-supply alarm threshold voltage (in volts) (5R7/R6) + 5 where R6 and R7 are in the same units. TEST (Pin 16) This input has an on-chip pull-down device and is used to manually invoke a test mode. The Pushbutton Test mode is initiated by a high level at Pin 16 (usually depression of a S.P.S.T. normally-open pushbutton switch to VDD). After one oscillator cycle, IRED pulses approximately every 1.0 second, regardless of the presence of smoke. Additionally, the amplifier gain is increased by automatic selection of C1. Therefore, the background reflections in the smoke chamber may be interpreted as smoke, generating a simulated-smoke condition. After the second IRED pulse, a successful test activates the horn-driver and I/O circuits. The active I/O allows remote signaling for system testing. When the Pushbutton Test switch is released, the Test input returns to VSS due to the on-chip pull-down device. After one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulated-smoke condition. After two additional IRED pulses, less than three seconds, the IC exits the alarm mode and returns to standby timing. For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145012 tion mode, Pin 16 (Test) must be pulled below the VSS pin with 100 A continuously drawn out of the pin for at least one cycle on the OSC pin. To exit this mode, the Test pin is floated for at least one OSC cycle. In the calibration mode, the IRED pulse rate is increased to one for every OSC cycle. Also, Strobe is always active low. CALIBRATION To facilitate checking the sensitivity and calibrating smoke detectors, the MC145012 can be placed in a calibration mode. In this mode, certain device pins are controlled/reconfigured as shown in Table 1. To place the part in the calibra- Table 1. Configuration of Pins in the Calibration Mode Pin Comment I/O 7 Disabled as an output. Forcing this pin high places the photo amp output on Pin 1 or 2, as determined by Low-Supply Trip. The amp's output appears as pulses and is referenced to VDD etc. Low-Supply Trip 15 If the I/O pin is high, Pin 15 controls which gain capacitor is used. Low: normal gain, amp output on Pin 1. High: supervisory gain, amp output on Pin 2. Feedback 10 Driving this input high enables hysteresis (10% gain increase) in the photo amp; Pin 15 must be low. OSC 12 Driving this input high brings the internal clock high. Driving the input low brings the internal clock low. If desired, the RC network for the oscillator may be left intact; this allows the oscillator to run similar to the normal mode of operation. Silver 9 This pin becomes the smoke comparator output. When the OSC pin is toggling, positive pulses indicate that smoke has been detected. A static low level indicates no smoke. Brass 8 This pin becomes the smoke integrator output. That is, 2 consecutive smoke detections are required for "on" (static high level) and 2 consecutive no-detections for "off" (static low level). DO NOT RUN ANY ADDITIONAL TRACES IN THIS REGION C1 PIN 1 R14 C2 PIN 16 R11 R8 D2 MOUNTED IN CHAMBER PIN 9 R10 Freescale Semiconductor, Inc... Description PIN 8 NOTES: Illustration is bottom view of layout using a DIP. Top view for SOIC layout is mirror image. Optional potentiometer R9 is not included. Drawing is not to scale. Leads on D2, R11, R8, and R10 and their associated traces must be kept as short as possible. This practice minimizes noise pick up. Pin 3 must be decoupled from all other traces. Figure 6. Recommended PCB Layout Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-53 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA Low-Power CMOS MC145017 Ionization Smoke Detector IC with Temporal Pattern Horn Driver The MC145017, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. 16 * Ionization Type with On-Chip FET Input Comparator 1 * Piezoelectric Horn Driver P SUFFIX PLASTIC DIP CASE 648-08 * Guard Outputs on Both Sides of Detect Input Freescale Semiconductor, Inc... * Input-Production Diodes on the Detect Input * Low-Battery Trip Point, Internally Set, can be Altered Via External Resistor * Detect Threshold, Internally Set, can be Altered Via External Resistor ORDERING INFORMATION MC145017P PLASTIC DIP * Pulse Testing for Low Battery Uses LED for Battery Loading * Comparator Outputs for Detect and Low Battery * Internal Reverse Battery Protection PIN ASSIGNMENT (16 PIN DIP) * Supports NFPA 72, ANSi 53.41, and ISO 8201 Audible Emergency Evacuation Signals Detect Comp. Out 1 16 Guard Hi-Z N/C 2 15 Detect Input Low V Set 3 14 Guard Lo-Z Low V Comp. Out 4 13 Sensitivity Set LED 5 12 Osc Capacitor VDD 6 11 Silver Timing Resistor 7 10 Brass Feedback 8 9 VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Rating Symbol DC Supply Voltage Value *0.5 to + 15 VDD Unit V Vin *0.25 to VDD + 0.25 DC Current Drain per Input Pin, Except Pin 15 = 1 mA I 10 mA DC Current Drain per Output Pin I 30 mA Input Voltage, All Inputs Except Pin 8 Storage Temperature Range Tstg *10 to + 60 *55 to + 125 Reverse Battery Time tRB 5.0 Operating Temperature Range TA V C C s * Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that Vin and Vout be constrained to the range VSS (Vin or Vout) VDD. v v REV 4 4-54 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145017 RECOMMENDED OPERATING CONDITIONS (Voltages referenced to VSS) Symbol Value Unit VDD 9.0 V Timing Capacitor -- 0.1 F Timing Resistor -- 8.2 M Battery Load (Resistor or LED) -- 10 mA Parameter Supply Voltage ELECTRICAL CHARACTERISTICS (Voltages referenced to VSS, TA = 25C) Symbol VDD Vdc Min Typ Max Unit Operating Voltage VDD -- 6.0 -- 12 V Output Voltage Piezoelectric Horn Drivers (IOH = 16 mA) Comparators (IOH = 30 A) Piezoelectric Horn Drivers (IOL = +16 mA) Comparators (IOL = +30 A) VOH 7.2 9.0 7.2 9.0 6.3 8.5 -- -- -- 8.8 -- 0.1 -- -- 0.9 0.5 Output Voltage -- LED Driver, IOL = 10 mA VOL 7.2 -- -- 3.0 Output Impedance, Active Guard Pin 14 Pin 16 Lo-Z Hi-Z 9.0 9.0 -- -- -- -- 10 1000 Operating Current (Rbias = 8.2 M) IDD 9.0 12.0 -- -- 3.2 -- 7.0 10.0 Input Current -- Detect (40% R.H.) Iin 9.0 -- -- Input Current, Pin 8 Iin 9.0 -- -- Input Current @ 50C, Pin 15 Iin -- -- Internal Set Voltage Low Battery Sensitivity Vlow Vset 9.0 -- Hysteresis vhys Offset Voltage (measured at Vin = VDD/2) Active Guard Detect Comparator VOS Freescale Semiconductor, Inc... Characteristic * * VOL V V V k A A -- "1.0 "0.1 "6.0 7.2 47 -- 50 7.8 53 V %VDD 9.0 75 100 150 mV -- -- -- -- "100 "50 mV 9.0 9.0 VSS *10 pA pA Input Voltage Range, Pin 8 Vin -- -- VDD + 10 V Input Capacitance Cin -- -- 5.0 -- pF Common Mode Voltage Range, Pin 15 Vcm -- 0.6 -- VDD *2 V # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-55 Freescale Semiconductor, Inc. MC145017 TIMING PARAMETERS (C = 0.1 F, Rbias = 8.2 M, VDD = 9.0 V, TA = 25C, See Figure 6) Characteristics Oscillator Period Symbol Min Max Units tCI 1.46 37.5 1.85 45.8 s ms No Smoke Smoke tr 10.1 12.3 ms Horn Output (During Smoke) On Time Off Time PWon PWoff 450 450 550 550 ms ms LED Output Pulses Between On Time tLED PWon 35.0 10.1 44.5 12.3 s ms Horn Output (During Low Battery) Pulses On Time Between ton toff 10.1 35.0 12.3 44.5 ms s Freescale Semiconductor, Inc... Oscillator Rise Time VDD VDD 4 80 K 3 8 LOW BATTERY COMP. PIEZOELECTRIC HORN DRIVER - 11 LATCH + 10 7 VDD VDD OSCILLATOR TIMER 1045 K 13 + LED DRIVER LATCH 1125 K 6 9 5 12 - 1 15 DETECT INPUT + - 14 LO-Z VDD 16 HI-Z ACTIVE GUARD Figure 1. Block Diagram 4-56 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 100.0 10.0 TA = 25C TA = 25C ID , DRAIN CURRENT (mA) ID , DRAIN CURRENT (mA) VDD = 9.0 Vdc 10.0 VDD = 7.2 Vdc 1.0 0.1 VDD = 9.0 Vdc or 7.2 Vdc 1.0 0.1 P-CH SOURCE AND N-CH SINK CURRENT 0.01 0 1 2 3 4 5 6 7 8 9 10 0 1 2 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) 3 4 5 6 8 9 10 9 10 Figure 3. Typical Comparator Output I-V Characteristic 1000.0 1000.0 TA = 25C ID , DRAIN CURRENT (mA) TA = 25C VDD = 9.0 Vdc 100.0 VDD = 9.0 Vdc 100.0 VDD = 7.2 Vdc 10.0 VDD = 7.2 Vdc 10.0 P-CH SOURCE CURRENT 1.0 0 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 2. Typical LED Output I-V Characteristic ID , DRAIN CURRENT (mA) Freescale Semiconductor, Inc... MC145017 1 2 3 4 5 6 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) N-CH SINK CURRENT 8 9 10 1.0 0 1 2 3 4 5 6 7 8 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 4. Typical P Horn Driver Output I-V Characteristic Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-57 Freescale Semiconductor, Inc. MC145017 DEVICE OPERATION Freescale Semiconductor, Inc... TIMING The internal oscillator of the MC145017 operates with a period of 1.65 seconds during no-smoke conditions. Each 1.65 seconds, internal power is applied to the entire IC and a check is made for smoke, except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. DETECT CIRCUITRY If smoke is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 500 ms on, 500 ms off. During the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. During smoke conditions the low battery alarm is inhibited, but the LED pulses at a 1.0 Hz rate. An active guard is provided on both pins adjacent to the detect input. The voltage at these pins will be within 100 mV of the input signal. This will keep surface leakage currents to a minimum and provide a method of measuring the input voltage without loading the ionization chamber. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. SENSITIVITY/LOW BATTERY THRESHOLDS Both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (please see Figure 1) connected between VDD and VSS. These voltages can be altered by external resistors connected from pins 3 or 13 to either VDD or VSS. There will be a slight interaction here due to the common voltage divider network. The sensitivity threshold can also be set by adjusting the smoke chamber ionization source. TEST MODE Since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or time-consuming. By forcing Pin 12 to VSS, the power strobing is bypassed and the outputs, Pins 1 and 4, constantly show smoke/no smoke and good battery/low battery, respectively. Pin 1 = VDD for smoke and Pin 4 = VDD for low battery. In this mode and during the 10 ms power strobe, chip current rises to approximately 50 A. LED PULSE The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 11.6 ms. If the LED is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 mA. HYSTERESIS When smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. This yields approximately 100 mV of hysteresis and reduces false triggering. 1M 1M TEST 1 16 MC145017 330 0.1 F + 2 15 3 14 4 13 5 12 6 11 7 10 8 9 0.1 F 8.2 M 9V 1.5 M* 0.001 F 220 k* *NOTE: Component values may change depending on type of piezoelectric horn used. Figure 5. Typical Application as Ionization Smoke Detector 4-58 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. OSC PIN 12 1 2 3 4 5 6 7 8 9 23 24 1 6 12 MC145017 18 24 SMOKE - N -Y SMOKE - N -Y NO SMOKE, LOW BATTERY LATCH ALARM CONDITION %([100 mV LEVEL SHIFT) HYST PIN 13 Freescale Semiconductor, Inc... NO SMK SMOKE NO SMK NO LOW BAT LOW BAT - Y -N HORN - ON - OFF OSC PIN 12 LOW BATTERY CHIRP & LED - OFF - ON NFPA MOD & LOW BAT - Y -N (NOTE 1) HORN - ON - OFF LED - OFF - ON 24 CLOCKS 24 CLOCKS Figure 6. MC145017 Timing Diagram NOTES: 1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off. 2. Comparators are strobed once per cycle (1.65 sec for no smoke, 40 msec for smoke). NFPA72: TEMPORAL HORN MODULATION PATTERN 0.5 SEC 0.5 SEC 0.5 SEC 0.5 SEC 0.5 SEC 1.5 SEC 83 msec 167 msec TRADITIONAL 4/6 HORN MODULATION PATTERN Figure 7. Horn Modulation Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-59 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA MC145018 Low-Power CMOS Freescale Semiconductor, Inc... Ionization Smoke Detector IC with Interconnect and Temporal Horn Driver 16 1 P SUFFIX PLASTIC DIP CASE 648-08 The MC145018, when used with an ionization chamber and a small number of external components, will detect smoke. When smoke is sensed, an alarm is sounded via an external piezoelectric transducer and internal drivers. This circuit is designed to operate in smoke detector systems that comply with UL217 and UL268 specifications. * Ionization Type with On-Chip FET Input Comparator ORDERING INFORMATION MC145018P PLASTIC DIP * Piezoelectric Horn Driver * Guard Outputs on Both Sides of Detect Input * Input-Protection Diodes on the Detect Input PIN ASSIGNMENT (16 PIN DIP) * Low-Battery Trip Point, Internally Set, can be Altered Via External Resistor * Detect Threshold, Internally Set, can be Altered Via External Resistor Detect Comp. Out 1 16 Guard Hi-Z I/O 2 15 Detect Input * Internal Reverse Battery Protection Low V Set 3 14 Guard Lo-Z * Strobe Output for External Trim Resistors Strobe Out 4 13 Sensitivity Set LED 5 12 Osc Capacitor * Pulse Testing for Low Battery Uses LED for Battery Loading * Comparator Output for Detect * I/O Pin Allows Up to 40 Units to be Connected for Common Signaling * Supports NFPA 72, ANSi 53.41, and ISO 8201 Audible Emergency Evacuation Signals * Power-On Reset Places IC in Standby Mode VDD 6 11 Silver Timing Resistor 7 10 Brass Feedback 8 9 VSS MAXIMUM RATINGS* (Voltages referenced to VSS) Rating Symbol DC Supply Voltage Value *0.5 to + 15 VDD Unit V Vin *0.25 to VDD + 0.25 DC Current Drain per Input Pin, Except Pin 15 = 1 mA I 10 mA DC Current Drain per Output Pin I 30 mA Input Voltage, All Inputs Except Pin 8 Storage Temperature Range Tstg *10 to + 60 *55 to + 125 Reverse Battery Time tRB 5.0 Operating Temperature Range TA V C C s * Maximum Ratings are those values beyond which damage to the device may occur. This device contains circuitry to protect the inputs against damage due to high static voltages or electric fields; however, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltages to this high impedance circuit. For proper operation it is recommended that Vin and Vout be constrained to the range VSS (Vin or Vout) VDD. v v REV 3 4-60 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MC145018 RECOMMENDED OPERATING CONDITIONS (Voltages referenced to VSS) Symbol Value Unit VDD 9.0 V Timing Capacitor -- 0.1 F Timing Resistor -- 8.2 M Battery Load (Resistor or LED) -- 10 mA Parameter Supply Voltage ELECTRICAL CHARACTERISTICS (Voltages referenced to VSS, TA = 25C) Symbol VDD Vdc Min Typ Max Unit Operating Voltage VDD -- 6.0 -- 12 V Output Voltage Piezoelectric Horn Drivers (IOH = 16 mA) Comparators (IOH = 30 A) Piezoelectric Horn Drivers (IOL = + 16 mA) Comparators (IOL = +30 A) VOH 7.2 9.0 7.2 9.0 6.3 8.5 -- -- -- 8.8 -- 0.1 -- -- 0.9 0.5 Output Voltage -- LED Driver, IOL = 10 mA VOL 7.2 -- -- 3.0 V Output Impedance, Active Guard Pin 14 Pin 16 Lo-Z Hi-Z 9.0 9.0 -- -- -- -- 10 1000 k Operating Current (Rbias = 8.2 M) IDD 9.0 12.0 -- -- 5.0 -- 9.0 12.0 A Input Current -- Detect (40% R.H.) Iin 9.0 -- -- Input Current, Pin 8 Iin 9.0 -- -- Input Current @ 50C, Pin 15 Iin -- -- Internal Set Voltage Low Battery Sensitivity Vlow Vset 9.0 -- Hysteresis vhys Offset Voltage (measured at Vin = VDD/2) Active Guard Detect Comparator VOS Freescale Semiconductor, Inc... Characteristic * * VOL V V A -- "1.0 "0.1 "6.0 7.2 47 -- 50 7.8 53 V %VDD 9.0 75 100 150 mV -- -- -- -- "100 "50 mV 9.0 9.0 *10 pA Input Voltage Range, Pin 8 Vin -- -- VDD + 10 V Input Capacitance Cin -- -- 5.0 -- pF Common Mode Voltage Range, Pin 15 Vcm -- 0.6 -- I/O Current, Pin 2 Input, VIH = VDD 2 Output, VOH = VDD 2 IIH IOH -- -- *4.0 25 -- -- * * VSS pA VDD *2 100 *16 V A mA # Data labelled "Typ'' is not to be used for design purposes but is intended as an indication of the IC's potential performance. Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-61 Freescale Semiconductor, Inc. MC145018 TIMING PARAMETERS (C = 0.1 F, Rbias = 8.2 M, VDD = 9.0 V, TA = 25C, See Figure 6) Characteristics Oscillator Period Symbol Min Max Units tCI 1.46 37.5 1.85 45.8 s ms No Smoke Smoke tr 10.1 12.3 ms Horn Output (During Smoke) On Time Off Time PWon PWoff 450 450 550 550 ms ms LED Output Pulses Between On Time tLED PWon 35.0 10.1 44.5 12.3 s ms Horn Output (During Low Battery) Pulses On Time Between ton toff 10.1 35.0 12.3 44.5 ms s Freescale Semiconductor, Inc... Oscillator Rise Time TO OTHER UNITS VDD VDD I/O 2 FEEDBACK 8 45 K LOW BATTERY COMPARATOR + LOW V SET 3 - 10 DETECT 1 COMP. OUT 280 K SENSITIVITY 13 SET BRASS + - 4 SILVER ALARM LOGIC DETECT COMPARATOR 325 K STROBE OUT 11 15 GUARD AMP + - POWER-ON RESET DETECT INPUT LO-Z VDD 14 HI-Z 16 OSC AND TIMING 5 LED VDD = PIN 6 VSS = PIN 9 12 7 VDD Figure 1. Block Diagram 4-62 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 100.0 10.0 TA = 25C TA = 25C ID , DRAIN CURRENT (mA) ID , DRAIN CURRENT (mA) VDD = 9.0 Vdc 10.0 VDD = 7.2 Vdc 1.0 0.1 VDD = 9.0 Vdc or 7.2 Vdc 1.0 0.1 P-CH SOURCE AND N-CH SINK CURRENT 0.01 0 1 2 3 4 5 6 7 8 9 10 0 1 2 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) 3 4 5 6 8 9 10 9 10 Figure 3. Typical Comparator Output I-V Characteristic 1000.0 1000.0 TA = 25C ID , DRAIN CURRENT (mA) TA = 25C VDD = 9.0 Vdc 100.0 VDD = 9.0 Vdc 100.0 VDD = 7.2 Vdc 10.0 VDD = 7.2 Vdc 10.0 P-CH SOURCE CURRENT 1.0 0 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 2. Typical LED Output I-V Characteristic ID , DRAIN CURRENT (mA) Freescale Semiconductor, Inc... MC145018 1 2 3 4 5 6 7 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) N-CH SINK CURRENT 8 9 10 1.0 0 1 2 3 4 5 6 7 8 VDS, DRAIN TO SOURCE VOLTAGE (Vdc) Figure 4. Typical P Horn Driver Output I-V Characteristic Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-63 Freescale Semiconductor, Inc. MC145018 DEVICE OPERATION Freescale Semiconductor, Inc... TIMING The internal oscillator of the MC145018 operates with a period of 1.65 seconds during no-smoke conditions. Each 1.65 seconds, internal power is applied to the entire IC and a check is made for smoke, except during LED pulse, Low Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24 clock cycles a check is made for low battery by comparing VDD to an internal zener voltage. Since very small currents are used in the oscillator, the oscillator capacitor should be of a low leakage type. DETECT CIRCUITRY If smoke is detected, the oscillator period becomes 41.67 ms and the piezoelectric horn oscillator circuit is enabled. The horn output is modulated 500 ms on, 500 ms off. During the off time, smoke is again checked and will inhibit further horn output if no smoke is sensed. During local smoke conditions the low battery alarm is inhibited, but the LED pulses at a 1.0 Hz rate. In remote smoke, the LED is inhibited as well. An active guard is provided on both pins adjacent to the detect input. The voltage at these pins will be within 100 mV of the input signal. This will keep surface leakage currents to a minimum and provide a method of measuring the input voltage without loading the ionization chamber. The active guard op amp is not power strobed and thus gives constant protection from surface leakage currents. Pin 15 (the Detect input) has internal diode protection against static damage. INTERCONNECT The I/O (Pin 2), in combination with VSS, is used to interconnect up to 40 remote units for common signaling. A Local Smoke condition activates a current limited output driver, thereby signaling Remote Smoke to interconnected units. A small current sink improves noise immunity during non- smoke conditions. Remote units at lower voltages do not draw excessive current from a sending unit at a higher voltage. The I/O is disabled for three oscillator cycles after power up, to eliminate false alarming of remote units when the battery is changed. SENSITIVITY/LOW BATTERY THRESHOLDS Both the sensitivity threshold and the low battery voltage levels are set internally by a common voltage divider (see Figure 1) connected between VDD and VSS. These voltages can be altered by external resistors connected from pins 3 or 13 to either VDD or VSS. There will be a slight interaction here due to the common voltage divider network. The sensitivity threshold can also be set by adjusting the smoke chamber ionization source. TEST MODE Since the internal op amps and comparators are power strobed, adjustments for sensitivity or low battery level could be difficult and/or time-consuming. By forcing Pin 12 to VSS, the power strobing is bypassed and the output, Pin 1, constantly shows smoke/no smoke. Pin 1 = VDD for smoke. In this mode and during the 10 ms power strobe, chip current rises to approximately 50 A. LED PULSE The 9-volt battery level is checked every 40 seconds during the LED pulse. The battery is loaded via a 10 mA pulse for 11.6 ms. If the LED is not used, it should be replaced with an equivalent resistor such that the battery loading remains at 10 mA. HYSTERESIS When smoke is detected, the resistor/divider network that sets sensitivity is altered to increase sensitivity. This yields approximately 100 mV of hysteresis and reduces false triggering. 1M 1 1M TEST 16 MC145018 TO OTHER UNITS 330 0.1 F + 2 15 3 14 4 13 5 12 6 11 7 10 8 9 0.1 F 8.2 M 9V 1.5 M* 0.001 F *NOTE: Component values may change depending on type of piezoelectric horn used. 220 k* Figure 5. Typical Application as Ionization Smoke Detector 4-64 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. OSC PIN 12 1 2 3 4 5 6 7 8 9 23 24 1 6 12 MC145018 18 24 SMOKE - N -Y SMOKE - N -Y NO SMOKE, LOW BATTERY LATCH ALARM CONDITION %([100 mV LEVEL SHIFT) HYST PIN 13 Freescale Semiconductor, Inc... NO SMK SMOKE NO SMK NO LOW BAT LOW BAT - Y -N HORN - ON - OFF OSC PIN 12 LOW BATTERY CHIRP & LED - OFF - ON NFPA MOD & LOW BAT - Y -N (NOTE 1) HORN - ON - OFF LED - OFF - ON 24 CLOCKS 24 CLOCKS Figure 6. MC145018 Timing Diagram NOTES: 1. Horn modulation is self-completing. When going from smoke to no smoke, the alarm condition will terminate only when horn is off. 2. Comparators are strobed once per cycle (1.65 sec for no smoke, 40 msec for smoke). 3. For timing under remote conditions, refer to MC14468 data sheet. NFPA72: TEMPORAL HORN MODULATION PATTERN 0.5 SEC 0.5 SEC 0.5 SEC 0.5 SEC 0.5 SEC 1.5 SEC 83 msec 167 msec TRADITIONAL 4/6 HORN MODULATION PATTERN Figure 7. Horn Modulation Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-65 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR APPLICATION NOTE AN1690 Alarm IC General Applications Overview Prepared by: Leticia Gomez and Diana Pelletier Sensor Applications Engineering Motorola Semiconductor Products Sector Phoenix, Arizona also has a logical output that can be used to drive other outputs such as an LED. The MC14600 alarm threshold and oscillator speed are set externally providing system design flexibility. Figure 2 is a detailed block diagram of the MC14600 that includes the pin numbers referenced in this document. Freescale Semiconductor, Inc... INTRODUCTION The MC14600, an IC designed for alarm applications, is a versatile part that can easily be configured with a minimum number of external components to serve a wide range of alarm applications and circuit configurations. For example, the MC14600 can be used in systems that detect pressure and temperature change, liquid levels, motion or intrusion. This application note presents considerations in interfacing external components to the MC14600 and an approach for configuring it with a latch. The MC14600 Alarm IC can be simply described as a comparator that determines whether an alarm condition exists and in response drives a piezo horn. As illustrated in Figure 1 the MC14600 is more than a comparator and a horn driver. It drives an LED to indicate the device is working and has internal low battery detection circuitry. In the event of a low battery the MC14600 provides the signal to chirp the piezo horn. It VDD - DETECT COMPARATOR OUT 3 ALARM THRESHOLD - LED PIEZO HORN LOW BATTERY DETECTION LOGICAL OUTPUT Figure 1. Alarm IC Concept HORN FEEDBACK 8 4 11 LOW BATTERY COMPARATOR + 1 ALARM 13 THRESHOLD + VDD LOW V COMP. OUT LOW V SET INPUT HORN OUT 2 10 HORN OUT 1 ALARM LOGIC DETECT COMPARATOR - + ALARM DETECT 15 INPUT GUARD AMP + VDD OSC AND TIMING HI-Z 5 LED 16 - Cosc 12 7 VDD = PIN 6 VSS = PIN 9 Rbias VDD Figure 2. MC14600 Block Diagram REV 3 4-66 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN1690 ALARM THRESHOLD ADJUSTMENTS PIEZO HORN INTERFACE The alarm trigger point (alarm threshold) is set externally to any voltage level with a simple voltage divider connected to pin 13. For instance, to connect the Alarm IC to a sensor that has an output of 1.0 V during a no alarm condition and 4.0 V during an alarm condition, the alarm threshold voltage could be set to 3.0 V using a 2 M and a 1 M resistor connected between VDD and ground (See Figure 3). Pin 13 connects internally to the negative input of the Detect Comparator. Based on the input impedance of the Detect Comparator the maximum suggested total resistance for the threshold voltage divider is 10 M. The MC14600 contains on-board horn driver circuitry to drive three leaded piezo horns. A three leaded horn is considered self-driven, having a feedback pin that is connected to a closed loop oscillation circuit. The MC14600 uses pin 8 (Horn Feedback), pin 10 (Horn Out 1) and pin 11 (Horn Out 2) to interface to a piezo horn and achieve the drive circuit. Pin 10 and pin 11 alternate their output providing the oscillation for the horn. Three external components are required to interface a piezo horn to the Alarm IC: R1, C1 and R2 (Figure 4). R1 is usually around 1.5 M and is the least critical component as it only biases the horn. R2 and C1 are critical to achieve maximum horn output. The two components must be set so that the value of 1/(R2*C1) is close to the resonant frequency of the horn being used. Table 2 lists a common horn frequency and potential external components that can be used for R2 and C1. Freescale Semiconductor, Inc... VDD 8 2M C1 FDBK PIN 13 OUT 2 11 OUT 1 10 R1 R2 1M Figure 3. Alarm Threshold Voltage Divider ALARM LOGIC OSCILLATOR The master clock frequency for the MC14600 is determined by the external components Rbias (pin 7) and Cosc (pin 12). This RC network provides the timing for the various functions conducted by the IC. The oscillator timing affects the period between LED pulses, alarm signal sampling, and the horn output pulses and power consumption. A standard RC network for the MC14600 oscillator uses an 8.2 M resistor (Rbias) connected from VDD to pin 7 and a 0.1 uF capacitor (Cosc) connected from pin 12 to ground. This configuration will provide a period of approximately 1.65 sec in standby and 41.67 msec in alarm. A change in oscillator speed is accomplished by changing the resistor and capacitor values previously stated. Changing the oscillator timing will not change the horn pattern but it will change the speed at which it's delivered. The table below lists examples of RC values and measured sampling periods achieved with those values (deviation from theoretical values are due to tolerance in components). Table 1. Oscillator Period vs. Rbias and Cosc Value Rbias 5.6 M Cosc 0.01 F Period (no alarm) Period (alarm) 93 msec 2.3 msec 8.2 M 0.01 F 142 msec 3.4 msec 10 M 0.01 F 172 msec 3.9 msec 5.6 M 0.1 F 1.4 sec 32 msec 8.2 M 0.1 F 2.2 sec 50 msec 10 M 0.1 F 2.7 sec 60 msec 8.2 M 1.0 F 20.1 sec 456 msec Motorola Sensor Device Data Figure 4. Piezo Horn Interface to MC14600 Table 2. External Components for a 3.4 kHz Three Leaded Piezo Horn Horn Osc. Frequency 3.4 " 0.4 kHz R1 R2 C1 1/(R2*C1) 1.5 M 820 k 1.5 M 1.5 M 200 k 200 k 120 k 100 k 1.5 nF 1.5 nF 2.2 nF 2.2 nF 3.33 kHz 3.33 kHz 3.79 kHz 4.55 kHz LOW BATTERY THRESHOLD ADJUSTMENTS The Alarm IC has a typical internal low battery reference voltage of 6 V. An internal resistor divider string provides a voltage of 80% of VDD which is compared to the 6 V reference voltage (See Figure 5). This results in a low battery condition and horn chirp if the VDD level is decreased to approximately 7.5 V. The percentage of VDD that is compared can be changed by adding a resistor to pin 3. A resistor from pin 3 to VDD will lower the percentage while a resistor from pin 3 to GND will increase the percentage. The low battery comparator information will be latched only during the LED pulse. Testing of the voltage at pin 3 should be done during the LED pulse for confirmation. It should also be measured through a high impedance buffer to avoid altering the voltage level. ALARM LATCHING APPROACHES There are detection applications where the event that triggers the alarm can be instantaneous, such as shock or motion. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-67 Freescale Semiconductor, Inc. AN1690 VDD LOW V COMP. OUT 4 VDD VDD VDD Internal to MC14600 100 - LOW V SET 3 R3 DETECT COMP. OUT RESET SWITCH + 1 ALARM DETECT INPUT (PIN 15) R1 OSC AND TIMING + 13 - ALARM THRESHOLD Freescale Semiconductor, Inc... R2 Figure 5. Low Battery Detection Circuitry In this case the Alarm IC would alarm for the brief moment that the event occurred and then stop. This is not always desirable, in particular during events where safety is of concern. A latch can be implemented using the concept of hysteresis to alter the alarm threshold level and therefore remain in an alarm condition. It is very simple as it requires only one resistor, R3, connected to pin 1 (Detect Comp. Out.) and added in series to the alarm threshold voltage divider, R1 and R2, on pin 13 (See Figure 6). During a no alarm condition pin 1 is high which makes the alarm threshold voltage divider look like it would without R3 connected, keeping the alarm threshold at the initial desired point. When an alarm condition occurs pin 1 goes low, which in turn dramatically lowers the threshold voltage into the alarm comparator. When the alarm signal ends and the input voltage into pin 15 decreases, the alarm condition does not end because the alarm threshold has been lowered to below a standby voltage level. The MC14600 will continue in an alarm condition until the unit is RESET or pin 15 receives a signal below this alarming threshold. A RESET is implemented by connecting a switch to pin 1 that will toggle to VDD through a resistor. This solution has the possibility that it will not latch on to the alarm condition indefinitely. As described above it is essentially just lowering the alarm threshold voltage so if the output from the sensor during a no alarm condition is below this threshold the latch will not work. Figure 6. Latch Using Resistor in Series with Threshold Divider or circuit that will produce a change in voltage that corresponds to an environmental change. For example, a simple circuit around a thermistor could cause the MC14600 to alarm when the temperature gets too high. A phototransistor could be connected to cause an alarm for either the absence or existence of light. Motorola also has sensors, specifically accelerometers and pressure sensors, that could be used as the input to the MC14600. An accelerometer, such as Motorola's MMA1201P, could be used to sense a shock or vibration. A possible solution is shown in Figure 7. The MC7805 is a voltage regulator that provides the 5 V supply required by the MMA1201P. Since the output of the MMA1201P resulting from a shock or vibration is very short some simple peak detection circuitry is required to keep the signal high long enough for the MC14600 to latch onto the alarm condition. 5V 7805 D1 1.0 F SAMPLE DETECTION INPUTS The MC14600 is a versatile device because its high impedence input pin allows it to be connected to a variety of systems and input signals. All that is required for an input is a device 4-68 OUTPUT TO PIN 15 (ALARM DETECT INPUT) MMA1201P 10 M Figure 7. Shock and Vibration Detection Circuit www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Motorola's pressure sensors can also provide the input to the MC14600. The MPX5000 series includes a wide variety of compensated and integrated pressure sensors with different pressure ranges, packaging and measurement options. One possible sensor is the MPXV5010. The output of the MPXV5010 can be fed directly into the input of the MC14600 (pin 15). If the latch described above is used with a pressure sensor resistors may be required at the output of the MPXV5010 to scale the output voltage (See Figure 8). This is because the output voltage for pressure sensors in the MPX5000 series under no pressure is 0.2 V, which may be below the lowered alarm threshold. (See previous section.) AN1690 VDD MPXV5010 OUTPUT TO PIN 15 (ALARM DETECT INPUT) Figure 8. Pressure Detection Circuit Freescale Semiconductor, Inc... CONCLUSION The MC14600 offers a simple solution for use in a wide variety of alarm applications. With a high impedance input pin it can be connected to many types of sensor devices. For sensor inputs that require a latched alarm condition there are several simple ways to add this option to the MC14600. It has the feature of not having a predetermined alarm threshold which Motorola Sensor Device Data gives it the flexibility of being set to any level as required by the application. The MC14600 has an internal horn driver that can drive a three leaded piezo horn with the addition of two resistors and one capacitor. The MC14600 integrates the features desired in alarm devices into a small and simple package that is still flexible enough for all types of alarm applications. www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-69 MOTOROLA Freescale Semiconductor, Inc. SEMICONDUCTOR TECHNICAL DATA AN4009 Alarm IC Sample Applications Prepared by: Rudi Lenzen Application Engineer, Toulouse France Freescale Semiconductor, Inc... INTRODUCTION The MC14600 is an integrated circuit (IC) designed for low-cost applications requiring an alarm to be triggered and heard. This device affords the designer a low-cost, easy-to-integrate solution, where board space and design time are at a premium. The Alarm IC can be used in multiple applications, such as personal, home and auto safety/security devices; door, gate and pool alarms; and even toys, where lasers and motion are employed, for example. However, this paper's purpose is to introduce you to just a few applications for which the MC14600 is a perfect fit. GAS SENSOR APPLICATION The MC14600, used with a flammable gas sensor and a few added components, provides a reliable solution for gas detection. When gas leakage is detected, the sensing resistor decreases typically by a factor 3 or 4 as the gas concentration reaches 10 percent of the lower explosive limit. During the calibration sequence (test under gas), a variable resistor is used to set the trigger level of the Alarm IC comparator which, in response, drives a piezo horn. By adding a thermistor--with negative temperature coefficient (NTC) in this case--in the detection circuit, the variation of the sensor resistance with temperature is easily compensated, avoiding false alarms when the room temperature increases. The logical output is useful to signal a remote control station that a gas leakage has been detected. When using a low power sensor, the circuit is fully compliant with a portable solution enhanced by the integrated low battery comparator indicating the state of the power supply. TEMPERATURE LEVEL DETECTOR When connected to a simple network of thermistor and resistors, the Alarm IC provides a portable solution for temperature control and supervision. The example hereafter uses an NTC thermistor. An audible alarm will sound when the threshold value at the comparator input is reached. A logic output is usable for starting either a fan or a heater depending upon the required temperature. V SUPPLY ALARM IC R TH LED P15 P13 RSENSOR PIEZO-HORN LOGICAL LOW BATTERY DETECTION V SUPPLY CALIBRATION RESISTOR + - R TH ALARM IC Figure 2. Temperature Level Example LED P15 + - PIEZO-HORN P13 LOGICAL LOW BATTERY DETECTION Figure 1. Gas Detection Example REV 0 4-70 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. AN4009 WATER LEVEL DETECTOR FILTER MONITOR A single probe connected directly on the detection pin of the Alarm IC provides a portable solution for water level detection. When liquid enters in contact with the probe, the resistor between the detection pin and the supply drops from an open circuit to a measurable value. With an appropriate choice of bridge resistors, the presence of liquid will trigger the comparator. The logic level can be connected to any monitoring system allowing pump starting, floodgate closing and others. This simple system is useful for numerous applications, such as swimming pool water level alarms, defrosting water level detectors, and in-house flood alarms. An ideal solution for air cleanliness control is provided when the Alarm IC is directly connected to an MPX5000 series pressure sensor. This sensor family is compensated in temperature and has its output signal directly exploitable (internally amplified). Therefore, the sensor can be connected to the detection pin of the circuit without any additional component. When a certain level of dust affects the efficiency of the filter, a differential pressure is measured and the Alarm IC comparator is triggered. V SUPPLY ALARM IC V SUPPLY ALARM IC LED MPX5XXX SERIES LED P15 + - PIEZO-HORN P13 + - P13 PIEZO-HORN LOGICAL LOGICAL LOW BATTERY DETECTION LOW BATTERY DETECTION Figure 5. Pressure Change (Filter) Example Figure 3. Water-Level Detection Example MOTION INDICATOR The Alarm IC can be used to detect motion and can be integrated into products, such as an ordinary clothes iron, where this is critical. Used with a low G accelerometer and a few logic components, the device can signal the user that there is a risk of clothes burning during use and that the iron must be shut off from the AC power after use. At the output of the accelerometer, a simple peak detection circuit is required to keep the signal active long enough. When no movement is detected, the output comparator is low and the counter starts. A first "beep" is heard after a few seconds to advise that there is a risk of clothes burning. If no movement is detected, the counting continues and drives a flip-flop connected to pin 15 of the Alarm IC. The alarm is triggered and will continue on until a new movement is detected, resetting the counter. V SUPPLY LOW G ACCELEROMETER Freescale Semiconductor, Inc... PROBE P15 + - ALARM IC LOGIC BLOCK INCLUDING COUNTER GATES FLIP-FLOP LED P15 + - PIEZO-HORN LOGICAL LOW BATTERY DETECTION Figure 4. Motion Indicator Example Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 4-71 Freescale Semiconductor, Inc. Package Outline Dimensions NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. -A- 16 9 DIM A B C D F G H J K L M S B 1 8 F C L S SEATING PLANE Freescale Semiconductor, Inc... -T- K H G D M J STYLE 1: PIN 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 16 PL 0.25 (0.010) T A M M CASE 648-08 ISSUE R 0.25 M B PIN'S NUMBER 2.65 2.35 A 10.55 8X 10.05 1 INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0_ 10 _ 0.020 0.040 0.25 0.10 16X 16 CATHODE CATHODE CATHODE CATHODE CATHODE CATHODE CATHODE CATHODE ANODE ANODE ANODE ANODE ANODE ANODE ANODE ANODE MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0_ 10 _ 0.51 1.01 STYLE 2: PIN 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. COMMON DRAIN COMMON DRAIN COMMON DRAIN COMMON DRAIN COMMON DRAIN COMMON DRAIN COMMON DRAIN COMMON DRAIN GATE SOURCE GATE SOURCE GATE SOURCE GATE SOURCE 0.49 0.35 6 0.25 M T A B PIN 1 INDEX 14X 4 A A 8 10.45 10.15 1.27 9 7.6 7.4 T B SEATING PLANE 16X 0.1 T 5 0.75 0.25 0.32 0.23 X45_ 1.0 0.4 SECTION A-A 7 0 NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 3. DATUMS A AND B TO BE DETERMINED AT THE PLANE WHERE THE BOTTOM OF THE LEADS EXIT THE PLASTIC BODY. 4. THIS DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSION OR GATE BURRS. MOLD FLASH, PROTRUSION OR GATE BURRS SHALL NOT EXCEED 0.15mm PER SIDE. THIS DIMENSION IS DETERMINED AT THE PLANE WHERE THE BOTTOM OF THE LEADS EXIT THE PLASTIC BODY. 5. THIS DIMENSION DOES NOT INCLUDE INTER-LEAD FLASH OR PROTRUSIONS. INTER-LEAD FLASH AND PROTRUSIONS SHALL NOT EXCEED 0.25mm PER SIDE. THIS DIMENSION IS DETERMINED AT THE PLANE WHERE THE BOTTOM OF THE LEADS EXIT THE PLASTIC BODY. 6. THIS DIMENSION DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL NOT CAUSE THE LEAD WIDTH TO EXCEED 0.62mm. CASE 751G-04 ISSUE D 4-72 www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. Section Five Freescale Semiconductor, Inc... Alphanumeric Device Index Alphanumeric Device Index . . . . . . . . . . . . . . . . . 5-2 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 5-1 Freescale Semiconductor, Inc. Freescale Semiconductor, Inc... Alphanumeric Device Index MC14467, 4-2, 4-3 MPX2053D, 3-34 MPX4080D, 3-54 MC14468, 4-2, 4-9 MPX2053DP, 3-34 MPX4100, 3-59 MC145010, 4-2, 4-24 MPX2053GP, 3-34 MPX4100A, 3-63, 3-64, 3-68 MC145011, 4-2, 4-34 MPX2053GSX, 3-34 MPX4100AP, 3-63, 3-68 MC145012, 4-2, 4-44 MPX2053GVP, 3-34 MPX4100AS, 3-63, 3-68 MC145017, 4-2, 4-54 MPX2100, 3-35 MPX4100ASX, 3-63 MC145018, 4-2, 4-60 MPX2100A, 3-38 MC14578, 4-2, 4-15 MPX2100AP, 3-38 MC14600, 4-2, 4-19 MPX2100ASX, 3-38 MMA1200D, 2-2, 2-5 MPX2100D, 3-38 MMA1201P, 2-2, 2-12 MPX2100DP, 3-38 MMA1220D, 2-2, 2-18 MPX2100GP, 3-38 MMA1250D, 2-2, 2-24 MPX2100GSX, 3-38 MMA1260D, 2-2, 2-30 MPX2102, 3-39 MMA1270D, 2-2, 2-36 MPX2102A, 3-42 MMA2200W, 2-2, 2-12 MPX2102AP, 3-42 MMA2201D, 2-2, 2-42 MPX2102ASX, 3-42 MMA2202D, 2-2, 2-48 MPX2102D, 3-42 MMA3201D, 2-2, 2-55 MPX2102DP, 3-42 MPX10, 3-15 MPX2102GP, 3-42 MPX10D, 3-18 MPX2102GSX, 3-42 MPX10DP, 3-18 MPX2102GVP, 3-42 MPX10GP, 3-18 MPX2200, 3-43 MPX10GS, 3-18 MPX2200A, 3-46 MPX12, 3-19 MPX2200AP, 3-46 MPX12D, 3-22 MPX2200D, 3-46 MPX12DP, 3-22 MPX2200DP, 3-46 MPX12GP, 3-22 MPX2200GP, 3-46 MPX2010, 3-23 MPX2200GVP, 3-46 MPX2010D, 3-26 MPX2202, 3-47 MPX2010DP, 3-26 MPX2202A, 3-50 MPX2010GP, 3-26 MPX2202AP, 3-50 MPX2010GS, 3-26 MPX2202ASX, 3-50 MPX2010GSX, 3-26 MPX2202D, 3-50 MPX53GP, 3-117 MPX2050, 3-27 MPX2202DP, 3-50 MPX5500, 3-118 MPX2050D, 3-30 MPX2202GP, 3-50 MPX5500D, 3-121 MPX2050DP, 3-30 MPX2202GSX, 3-50 MPX5500DP, 3-121 MPX2050GP, 3-30 MPX2202GVP, 3-50 MPX5700, 3-122 MPX2050GSX, 3-30 MPX2300DT1, 3-51 MPX5700A, 3-125 MPX2053, 3-31 MPX2301DT1, 3-51 MPX5700AP, 3-125 MPX4101A, 3-70, 3-74 MPX4105A, 3-75 MPX4115A, 3-79 MPX4200A, 3-84 MPX4250A, 3-88 MPX4250D, 3-93 MPX5010, 3-97 MPX5010D, 3-101 MPX5010DP, 3-101 MPX5010G6U, 3-101 MPX5010G7U, 3-101 MPX5010GP, 3-101 MPX5010GS, 3-101 MPX5010GSX, 3-101 MPX5050, 3-103 MPX5050D, 3-107 MPX5050DP, 3-107 MPX5050GP, 3-107 MPX5100, 3-108 5-2 MPX5100A, 3-113 MPX5100AP, 3-113 MPX5100D, 3-113 MPX5100DP, 3-113 MPX5100GP, 3-113 MPX5100GSX, 3-113 MPX53, 3-114 MPX53D, 3-117 MPX53DP, 3-117 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. MPX5700AS, 3-125 MPXH6115AC6U, 3-133 MPXV2053G, 3-31 MPX5700D, 3-125 MPXH6300A, 3-153 MPXV2053GP, 3-34 MPX5700DP, 3-125 MPXH6300A6T1, 3-156 MPXV2102DP, 3-42 MPX5700GP, 3-125 MPXH6300A6U, 3-156 MPXV2102G, 3-39 MPX5700GS, 3-125 MPXH6300AC6T1, 3-156 MPXV2102GP, 3-42 MPX5999D, 3-126, 3-129 MPXM2010, 3-158 MPXV2202DP, 3-50 MPXA4100A, 3-64 MPXM2010D, 3-160 MPXV2202G, 3-47 MPXM2010DT1, 3-160 MPXV2202GP, 3-50 MPXM2010GS, 3-160 MPXV4006DP, 3-173 MPXM2010GST1, 3-160 MPXV4006G, 3-170 MPXM2053, 3-161 MPXV4006G6U/T1, 3-173 MPXM2053D, 3-163 MPXV4006G7U, 3-173 MPXM2053DT1, 3-163 MPXV4006GC6U/T1, 3-173 MPXM2053GS, 3-163 MPXV4006GC7U, 3-173 MPXM2053GST1, 3-163 MPXV4006GP, 3-173 MPXM2102, 3-164 MPXV4115V, 3-174 MPXM2102A, 3-166 MPXV4115V6T1, 3-177 MPXM2102AS, 3-166 MPXV4115V6U, 3-177 MPXM2102AST1, 3-166 MPXV4115VC6U, 3-177 MPXM2102AT1, 3-166 MPXV5004DP, 3-182 MPXM2102D, 3-166 MPXV5004G, 3-179 MPXM2102DT1, 3-166 MPXV5004G6U/T1, 3-182 MPXM2102GS, 3-166 MPXV5004G7U, 3-182 MPXM2102GST1, 3-166 MPXV5004GC6U/T1, 3-182 MPXM2202, 3-167 MPXV5004GC7U, 3-182 MPXM2202A, 3-169 MPXV5004GP, 3-182 MPXM2202AS, 3-169 MPXV5004GVP, 3-182 MPXM2202AST1, 3-169 MPXV5010DP, 3-101 MPXM2202AT1, 3-169 MPXV5010G, 3-97 MPXM2202D, 3-169 MPXV5010G6U, 3-101 MPXM2202DT1, 3-169 MPXV5010G7U, 3-101 MPXM2202GS, 3-169 MPXV5010GC6T1, 3-101 MPXM2202GST1, 3-169 MPXV5010GC6U, 3-101 MPXV10GC, 3-15 MPXV5010GC6U/T1, 3-101 MPXH6101A, 3-70 MPXV10GC6T1, 3-18 MPXV5010GC7U, 3-101 MPXH6101A6T1, 3-74 MPXV10GC6U, 3-18 MPXV5010GP, 3-101 MPXH6101A6U, 3-74 MPXV10GC7U, 3-18 MPXV5050DP, 3-107 MPXH6115A, 3-130 MPXV2010DP, 3-26 MPXV5050G, 3-103 MPXH6115A6T1, 3-133 MPXV2010G, 3-23 MPXV5050GP, 3-107 MPXH6115A6U, 3-133 MPXV2010GP, 3-26 MPXV53GC, 3-114, 3-117 MPXH6115AC6T1, 3-133 MPXV2053DP, 3-34 MPXV6115VC6U, 3-183 MPXA4100A6U/T1, 3-68 MPXA4100AC6U, 3-68 MPXA4101A, 3-70 MPXA4101AC6U, 3-74 Freescale Semiconductor, Inc... MPXA4115A, 3-79 MPXA4250A, 3-88 MPXA6115A, 3-130 MPXA6115A6T1, 3-133 MPXA6115A6U, 3-133 MPXA6115AC6T1, 3-133 MPXA6115AC6U, 3-133 MPXAZ4100A, 3-135 MPXAZ4100A6T1, 3-138 MPXAZ4100A6U, 3-138 MPXAZ4100AC6T1, 3-138 MPXAZ4100AC6U, 3-138 MPXAZ4115A, 3-140 MPXAZ4115A6T1, 3-143 MPXAZ4115A6U, 3-143 MPXAZ4115AC6T1, 3-143 MPXAZ4115AC6U, 3-143 MPXAZ6115A, 3-145 MPXAZ6115A6T1, 3-148 MPXAZ6115A6U, 3-148 MPXAZ6115AC6T1, 3-148 MPXAZ6115AC6U, 3-148 MPXC2011DT1, 3-150 MPXC2012DT1, 3-150 Motorola Sensor Device Data www.motorola.com/semiconductors For More Information On This Product, Go to: www.freescale.com 5-3 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. 5-4 For www.motorola.com/semiconductors More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. For More Information On This Product, Go to: www.freescale.com Freescale Semiconductor, Inc. HOW TO REACH US: USA/EUROPE/LOCATIONS NOT LISTED: Motorola Literature Distribution P.O. Box 5405, Denver, Colorado 80217 1-800-441-2447 or 480-768-2130 Freescale Semiconductor, Inc... JAPAN: Motorola Japan Ltd. SPS, Technical Information Center 3-20-1, Minami-Azabu Minato-ku Tokyo 106-8573, Japan 81-3-3440-3569 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd. Silicon Harbour Centre 2 Dai King Street Tai Po Industrial Estate Tai Po, N.T. Hong Kong 852-26668334 HOME PAGE: http://motorola.com/semiconductors Information in this document is provided solely to enable system and software implementers to use Motorola products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. Motorola reserves the right to make changes without further notice to any products herein. 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All other product or service names are the property of their respective owners. Motorola Inc. 2003 DL200/D, REV 5 For More Information On This Product, Go to: www.freescale.com