SILICON
MICROSTRUCTURES
INCORPORATED
SM5812/SM5852
Amplified Pressure Sensor
2005 SMI
Silicon Microstructures, Inc. ♦ 1701 McCarthy Blvd. ♦ Milpitas, CA 95035 ♦ USA
Tel: 408-577-0100 ♦ Fax: 408-577-0123 ♦ Sales@si-micro.com ♦ www.si-micro.com
Rev 1.4 6
_
05
• NOW WITH ACCESS TO DIGITAL TEMPERATURE AND CORRECTED DIGITAL PRESSURE
• LOW-COST, FULLY AMPLIFIED, CALIBRATED, AND COMPENSATED IN A SINGLE PACKAGE
• AVAILABLE FOR DIFFERENTIAL, SINGLE-ENDED DIFFERENTIAL, GAGE & ABSOLUTE APPLICATIONS
• MULTIPLE PRESSURE RANGES AVAILABLE TO MEASURE PRESSURE DOWN TO 0.15 PSI FULL-SCALE
AND UP TO 100 PSI FULL-SCALE
DESCRIPTION
The Silicon Microstructures SM5812 and
SM5852 series of OEM pressure sensors
combines state-of-the-art pressure sensor
technology with CMOS digital signal
processing technology to produce an
amplified, fully conditioned, multi-order
pressure and temperature compensated
sensor in a dual in-line package (DIP)
configuration.
Combining the pressure sensor with a
custom signal conditioning ASIC in a single
package simplifies the use of advanced
silicon micromachined pressure sensors.
Now, the pressure sensor can be mounted
directly to a standard printed circuit board
and an amplified, high level, calibrated
pressure signal can be acquired from the
digital interface or analog output. This
eliminates the need of additional circuitry,
such as a compensation network or micro-
controller containing a custom correction
algorithm.
The SM5812/SM5852 Series pressure
sensors are based on SMI's highly stable,
piezoresistive pressure sensor chips
mounted on a ceramic substrate. An
electronically programmable ASIC is
contained in the same package to provide
calibration and temperature compensation.
The model SM5812 is designed for
operating pressure ranges from 0-5 PSI up
to 0-100 PSI. The model SM5852 is
designed for operating pressure ranges from
0-0.15 PSI up to 0-3 PSI. For both models,
the sensor output is ratiometric with the
supply voltage.
FEATURES
• Amplified, calibrated, fully signal
conditioned output span of 4.0 VDC FS
(0.5 to 4.5 V signal)
• Digital temperature and calibrated
pressure available through I2C interface
• Output ratiometric with supply voltage
• Multi-order correction for pressure non-
linearity (factory programmed)
• Multi-order correction for temperature
coefficient of span and offset (factory
programmed)
• Gage, differential, and absolute versions
• SMI’s unique low-pressure die allows for
a full-scale pressure range of 0-0.15 PSI
TYPICAL APPLICATIONS
• Barometric measurement
• Medical instrumentation
• Pneumatic control
• Gas flow
• Respirators and ventilators
• Heating, Ventilation and Air Conditioning
(HVAC)
SM5812/SM5852
2005 SMI
Silicon Microstructures, Inc. ♦ 1701 McCarthy Blvd. ♦ Milpitas, CA 95035 ♦ USA
Tel: 408-577-0100 ♦ Fax: 408-577-0123 ♦ Sales@si-micro.com ♦ www.si-micro.com
Rev 1.4 6
_
05
THEORY OF OPERATION
The operation of the signal processor is
depicted in the block diagram below. The
external pressure sensor is a piezoresistive
bridge. This transduces the applied pressure
into an electronic signal, which is then inputted
into the integrating amplifier of the ASIC.
During the amplification step an offset
correction factor is added in order to allow
maximum gain for a given pressure while
minimizing the offset error.
The signal is then passed to an 11-bit analog
to digital converter (ADC). The ADC samples
the signal multiple times and uses the sum of
those samples as a 13-bit word.
A digital signal processor (DSP) is then used
to correct and calibrate the pressure signal.
The DSP provides multi-order correction of
both pressure and temperature non-linearity
through the use of factory-programmed
coefficients. A combined total of twenty
coefficients are available for correcting
pressure and temperature non-linearity. The
unique coefficients are determined during a
calibration process performed at the factory.
Factory calibration is the last step performed
which means the effect of the package on
the pressure signal will also be taken into
account. This provides a great advantage
over conventional laser-trimming
approaches.
The DSP outputs a corrected digital word,
which travels to a 12-bit digital to analog
converter (DAC) to provide a calibrated
analog output. In addition to the analog
output, the corrected pressure signal is
accessible through an I2C digital interface.
See SMI application note AN05-001 for a
detailed description of how to read out the
digital corrected pressure signal using the
I2C bus interface.
Switched
Capacitor
Integrateing
Amplifier
Analog
Timing
Control
2 MHz
Oscillator
Power-On
Reset
V
Temp
11-bit ADCMUX
EEPROM
Array
Band-gap
Output
Buffer
Analog
Output
SDA
SCL
Ground
+ 5 VDC
SMI Multi-Order Pressure and
Temperature Correction ASIC
Analog Component
Digital Component
External
Piezoresistive
Bridge
+ 5 VDC
Ground
DSP
(multi-order
correction of
pressure and
temperature
non-
linearities)
12-bit
Sigma-
Delta DAC
Digital Timing
and Control
Management
I
2
C Digital
Interface
SILICON
MICROSTRUCTURES
INCORPORATED
SM5812/SM5852
2005 SMI
Silicon Microstructures, Inc. ♦ 1701 McCarthy Blvd. ♦ Milpitas, CA 95035 ♦ USA
Tel: 408-577-0100 ♦ Fax: 408-577-0123 ♦ Sales@si-micro.com ♦ www.si-micro.com
Rev 1.4 6
_
05
CHARACTERISTICS FOR SM5812/SM5852 – SPECIFICATIONS
All parameters are measured at room temperature while applying 5.000V supply, unless otherwise specified.
Absolute1, Gage & Single2 Differential
MIN TYP MAX MIN TYP MAX UNITS NOTES
Zero output (absolute and gauge) 0.42 0.50 0.58 V 3
Zero output (differential) 2.42 2.50 2.58 V 3
Output Span 3.92 4.00 4.08 1.96 2.00 2.04 V FS 3, 4
0.15 PSI 3.80 4.00 4.20 1.90 2.00 2.10 V FS 3, 4
Linearity -0.5 +0.5 -0.5 +0.5 %FS 5
0.15 PSI -2.5 +2.5 -2.5 +2.5 %FS 5
Pressure hysteresis 5812 -0.1 +0.1 -0.1 +0.1 %FS
5852 -0.3 +0.3 -0.3 +0.3 %FS
Temperature coefficient - Zero -1.0 +1.0 -1.0 +1.0 %FS
0.15 PSI -2.5 +2.5 -2.5 +2.5 %FS
Temperature coefficient – Span -1.0 +1.0 -1.0 +1.0 %FS
0.15 PSI -2.0 +2.0 -2.0 +2.0 %FS
Thermal hysteresis -0.1 +0.1 -0.1 +0.1 %FS
Response Time 2 2 msec
Supply voltage 4.75 5.00 5.25 4.75 5.00 5.25 V 3, 7
Current consumption 10 10 mA
Overpressure 5812 3X 3X %FS 6
5852 15X 15X %FS 6
Operating temperature range -40 25 +125 -40 25 +125 °C
Compensated temperature range 0 25 +70 0 25 +70 °C
Storage temperature range -55 25 +135 -55 25 +135 °C
Media compatibility 8
Weight 3 3 gram
Notes:
1. Absolute parts are only offered in the SM5812 Series.
2. Single-ended parts (Pressure Type - S) have 2 ports and are for higher gain differential applications where the
differential pressure is always positive.
3. Sensor output is ratiometric to supply.
4. Full-scale (FS) is defined as zero pressure to rated pressure; differential parts can be used ±FS. Absolute and Gauge
zero output is 0.5 V typical and full-scale output is 4.5 V. Span is the difference between Full-scale output and zero
output, (4 V). For Differential parts, the negative full-scale is typically at 0.5 V, zero is typically 2.5 V, and positive full-
scale is 4.5 volts to give a span of ±2.0 V.
5. Defined as best fit straight line for positive pressure applied to the part
6. Or 225 PSI, whichever is less. Output amplifier will saturate at about 0.25 V for applied pressure below the rated Zero
and at about 4.75 V for applied pressure above the rated Full-scale.
7. A 100 nF filter capacitor must be placed between Vsupply and Ground.
8. Clean, dry gas compatible with wetted materials. Wetted materials include Pyrex glass, silicon, alumina ceramic, epoxy,
RTV, gold, aluminum, and nickel.
SM5812/SM5852
2005 SMI
Silicon Microstructures, Inc. ♦ 1701 McCarthy Blvd. ♦ Milpitas, CA 95035 ♦ USA
Tel: 408-577-0100 ♦ Fax: 408-577-0123 ♦ Sales@si-micro.com ♦ www.si-micro.com
Rev 1.4 6
_
05
ADDITIONAL INFORMATION
Package Dimensions & Pin-Out
PIN DESCRIPTION
1 NC
2 GROUND
3 NC
4 SERIAL DATA (SDA)
5 SERIAL CLOCK (SCL)
6 NC
7 Vexc = 5.000 VDC
8 ANALOG OUTPUT
Dual Inline Pin (DIP) Option
Surface Mountable Pin Option
Pin Numbers
(for both DIP & Surface Mount)
NOTES:
• Do not connect to NC pins.
• External connections to NC pins will
cause part malfunction.
• All dimensions are shown in inches.
• Tolerance on all dimensions
+0.005” unless otherwise specified.
Ordering Information Full-Scale Pressure Ranges
SM5812 PSI [kPa] SM5852 PSI [kPa]
005 5 [34.5] 001 0.15 [1.0]
015 15 [103.4] 003 0.30 [2.1]
030 30 [206.8] 008 0.80 [5.5]
060 60 [413.7] 015 1.50 [10.3]
100 100 [689.5] 030 3.00 [20.7]
Pin Configuration
3 : DIP pins, opposite direction of tubes
5 : Surface mountable pins,
opposite direction of tubes
Tube Length
L : Long (0.480" ± 0.005")
N : No tube
Pressure Type
A : Absolute (1 port)
D : Differential (2 ports)
G : Gauge (1 port)
S : Single-ended (2 ports)
Notes
1. Absolute configuration only available in SM5822.
2. Single-ended configuration is for higher gain differential applications where differential pressure
is always positive.
3. Other configurations available on large orders. Consult SMI for details.
SM5852 - 003 - D - 3 - L
Model Number
Pressure
Range
Pin Configuration
Tube
Length
Pressure
Type
Wiring Diagrams
SM5812/SM5852
ANALOG OUTPUT
GROUND
GROUND
100 nF
V
exc
= + 5.000 VDC
Wiring diagram for analog output
SM5812/SM5852
SERIAL CLOCK (SCL)
GROUND
GROUND
100 nF
V
exc
= + 5.000 VDC
SERIAL DATA (SDA)
Wiring diagram for digital output
Notice:
Silicon Microstructures, Inc. reserves the right to make changes to the product contained in this publication. Silicon Microstructures, Inc. assumes no responsibility for the
use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are free of patent infringement.
While the information in this publication has been checked, no responsibility, however, is assumed for inaccuracies.
Silicon Microstructures, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonabl
y
be expected to cause failure of a life-support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications.
