KITMPL115A2I2C - Freescale Semiconductor

Document Number: MPL115A2

Rev. 9, 02/2013

Freescale Semiconductor

Data Sheet: Technical Data

Miniature I2C Digital Barometer

The MPL1 15A2 is an absolute pressure sensor with a digital I2C output targeting

low cost applications. A miniature 5 x 3 x 1.2 mm LGA package is ideally suited

for the space constrained requirements of portable electronic devices. Low

current consumptions of 5 μA during Active mode and 1 μA du ring Shutdown

(Sleep) mode are essential when focusing on low-power applications. The wide

operating temperature range spans from -40°C to +105°C to fit demanding

environmental conditions.

The MPL115A2 employs a MEMS pressure sensor with a conditioning IC to

provide accurate pressure measurements from 50 to 115 kPa. An integrated

ADC converts pressure and temperature sensor readings to digitized outputs via

a I2C port. Factory calibration data is stored internally in an on-board ROM.

Utilizing the raw sensor output and calibration data, the host microcontroller

executes a compensation algorithm to render Compensated Absolute Pressure

with ±1 kPa accuracy.

The MPL115A2 pressure sensor’s small form factor, low power capability,

precision, and digital output optimize it for barometric measurement

applications.

Features

• Digitized pressure and temperature information together with programmed

calibration coefficients for host micro use.

• Factory calibrated

• 50 kPa to 115 kPa absolute pressure

• ±1 kPa accuracy

• 2.375V to 5.5V supply

• Integrated ADC

•I

2C Interface (operates up to 400 kHz)

•7-bit I

2C address = 0x60

• Monotonic pressure and temperature data outputs

• Surface mount RoHS compliant package

Application Examples

• Barometry (portable and desktop)

• Altimeters

• Weather stations

• Hard-disk drives (HDD)

• Industrial equipment

• Health monitoring

• Air control systems

ORDERING INFORMATION

Device Name Package Options Case No. # of Ports Pressure Type Digital

Interface

None Single Dual Gauge Differential Absolute

MPL115A2 Tray 2015 • • I2C

MPL115A2T1 Tape & Reel (1000) 2015 • • I2C

MPL115A2

50 to 115 kPa

Top View

MPL115A2

5.0 mm x 3.0 mm x 1.2 mm

Pin Connections

SDA

VDD

CAP

SHDN

GND

RST

SCL

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1 Block Diagram and Pin Descriptions

Figure 1. Block Diagram and Pin Connections

Table 1. Pin Description

Pin Name Function

1VDD VDD Power Supply Connection: VDD range is 2.375V to 5.5V.

2CAP 1 μF connected to ground.

3GND Ground

4SHDN Shutdown: Connect to GND to disable the device. When in shutdown, the part draws no more than 1 μA supply

current and all communications pins (RST, SCL, SDA) are high impedance. Connect to VDD for normal

operation.

5RST Reset: Connect to ground to disable I2C communications.

6NC NC: No connection

7SDA(1)

1. Use 4.7k pullup resistors for I2C communication.

SDA: Serial data I/O line

8SCL(1) I2C Serial Clock Input.

Diff

Amp

Temp

Sensor

MUX

ADC

SCL

GND

VDD

SDA

Temperature

Pressure

Coefficient

Storage

ADDR

Interface

SHDN

RST

CAP

Diff

Amp

Temp

Sensor

MUX

ADC

SCL

GND

VDD

SDA

Temperature

Pressure

Coefficient

Storage

ADDR

Interface

SHDN

RST

CAP

VDD

CAP

SHDN

SDA

RST

GND

SCL μC

1 μF

Microcontroller

4.7 k

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2 Mechanical and Electrical Specifications

2.1 Maximum Rati ngs

Voltage (with respect to GND unless otherw ise noted)

VDD........... ... .............. .............. .............. .............. .............. ......................... ........-0.3 V to +5.5 V

SHDN, RST, SDA, SCL ...............................................................................-0.3 V to VDD+0.3 V

Operating Temperature Range..........................................................................-40°C to +105°C

Storage Temperature Range .............................................................................-40°C to +125°C

Overpressure................................................................................................................1000 kPa

2.2 Operating Characteristics

VDD = 2.375 V to 5.5 V, TA = -40°C to +105°C, unless otherwise noted. Typical values are at VDD = 3.3 V, TA = +25°C.

Ref Parameters Symbol Conditions Min Typ Max Units

1 Operating Supply Voltage VDD 2.375 3.3 5.5 V

2 Supply Current IDD Shutdown (SHDN = GND) — — 1 μA

Standby — 3.5 10 μA

Average – at one measurement per second — 5 6 μA

Pressure Sensor

3 Range 50 — 115 kPa

4 Resolution —0.15—kPa

5 Accuracy -20ºC to 85ºC — — ±1 kPa

6 Power Supply Rejection Typical operating circuit at DC 0.1 — kPa/V

100 mV p-p 217 Hz square wave plus 100 mV

pseudo random noise with 10 MHz bandwidth 0.1 — kPa

7 Conversion Time

(Start Pressure and Temperature

Conversion)

tc Time between start convert command and

data available in the Pressure and

Temperature registers

—1.63 ms

8 Wakeup Time tw Time between leaving Shutdown mode

(SHDN goes high) and communicating with

the device to issue a command or read data.

—35ms

I2C I/O Stages: SCL, SDA

9 SCL Clock Frequency fSCL — — 400 kHz

10 Low Level Input Voltage VIL ——0.3V

DD V

11 High Level Input Voltage VIH 0.7VDD —— V

I2C Outputs: SDA

12 Data Setup Time tSU Setup time from command receipt to ready to

transmit 0—0.4s

I2C Addressing

MPL115A2 uses 7-bit addressing, does not acknowledge the general call address 0000000. Slave address has been set to 0x60 or 1100000.

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3 Overview of Functions/Operation

Figure 2. Sequence Flow Chart

The MPL1 15A interfaces to a host (or system) microcontroller in the user’s application. All communications are via I2C. A typical

usage sequence is as follows:

Initial Power-up

All circuit elements are active. I2C port pins are high impedance and associated registers are cleared. The device then enters

standby mode.

Reading Coefficient Data

The user then typically accesses the part and reads the coefficient data. The main circuits within the slave device are disabled

during read activity. The coefficients are usually stored in the host microcontoller loca l memory but can be re-read at any time.

It is not necessary to read the values stored in the host microcontroller multiple times because the coefficients within a device

are constant and do not change. However, note that the coefficients will be different from device to device, and cannot be used

for another part.

Data Conversion

This is the first step that is performed each time a new pre ssure reading is required which is initiated by the host sending the

CONVERT command. The main system circuits are activated (wake) in response to the command and after the conversion

completes, the result is placed into the Pressure and Temperature ADC output registers.

The conversion completes with in the maximum conversion time, tc (see Row 7, in the Operating Characteristics Table). The

device then enters standby mode.

Compensated Pressure Reading

After the conversion has been given sufficient time to complete, the host microcontroller reads the result from the ADC output

registers and calculates the Compensated Pressure, a barometric/atmospheric pressure value which is compensated for

changes in temperature and pressure sensor linearity. This is done using the coefficient data from the MPL115A and the raw

sampled pressure and temperature ADC output values, in a compensation equation (detailed later). Note that this is an absolute

pressure measurement with a vacuum as a reference.

From this step the host controller may either wait and then return to the Data Conversion step to obtain the next pressure reading

or it may go to the Shutdown step.

Reading

coeff ic ient dat a

Dat a c onv er s ion

Initial

powerup

Compensated

pres s ur e reading

Shutdown

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Shutdown

For longer periods of inactivity the user may assert the SHDN input by driving this pin low to reduce system power consumption.

This removes power from all internal circuits, including any registers. In the shutdown state, the Pressure and Temperature

registers will be reset, losing any previous ADC output values.

This step is exited by taking the SHDN pin high. Wait for the maximum wakeup time, tw (see Row 8, in the Operating

Characteristics Table), after which another pressure reading can be taken by transitioning to the data Conversion step.

For values with less than 16 bits, the lower LSBs are zero. For example, c12 is 14 bits and is stored into 2 bytes as follows:

c12 MS byte = c12[13:6] = [c12b13 , c12b12 , c12b11 , c12b10 , c12b9 , c12b8 , c12b7 , c12b6]

c12 LS byte = c12[5: 0] & “00” = [c12b5 , c12b4 , c12b3 , c12b2 , c12b1 , c12b0 , 0 , 0]

3.1 Pressure, Temperature and Coefficient Bit-Width Specifications

The table below specifies the initial coefficient bit-width specifications for the compensation algorithm and the specifications for

Pressure and Temperature ADC values.

Table 2. Device Memory Map

Address Name Description Size (bits)

0x00 Padc_MSB 10-bit Pressure ADC output value MSB 8

0x01 Padc_LSB 10-bit Pressure ADC output value LSB 2

0x02 Tadc_MSB 10-bit Temperature ADC output value MSB 8

0x03 Tacd_LSB 10-bit Temperature ADC output value LSB 2

0x04 a0_MSB a0 coefficient MSB 8

0x05 a0_LSB a0 coefficient LSB 8

0x06 b1_MSB b1 coefficient MSB 8

0x07 b1_LSB b1 coefficient LSB 8

0x08 b2_MSB b2 coefficient MSB 8

0x09 b2_LSB b2 coefficient LSB 8

0x0A c12_MSB c12 coefficient MSB 8

0x0B c12_LSB c12 coefficient LSB 8

0x0C Reserved* — —

0x0D Reserved* — —

0x0E Reserved* — —

0x0F Reserved* — —

0x10 Reserved — —

0x11 Reserved — —

0x12 CONVERT Start Pressure and Temperature Conversion —

*These registers are set to 0x00. These are reserved, and were previously utilized as Coefficient values, c11 and

c22, which were always 0x00.

Pressure, Temperature and Compensation Coefficient Specifications

a0 b1 b2 c12 Padc Tadc

Total Bits 16 16 16 14 10 10

Sign Bits 1 1 1 1 0 0

Integer Bits 12 2 1 0 10 10

Fractional Bits 313 14 13 0 0

dec pt zero pad 0 0 0 9 0 0

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Example Binary Format Definitions:

a0 Signed, Integer Bits = 12, Fractional Bits = 3 : Coeff a0 = S I11 I10 I9 I8 I7 I6 I5 I4 I3 I2 I1 I0 . F2 F1 F0

b1 Signed, Integer Bits = 2, Fractional Bits = 13 : Coeff b1 = S I1 I0 . F12 F11 F10 F9 F8 F7 F6 F5 F4 F3 F2 F1 F0

b2 Signed, Integer Bits = 1, Fractional Bits = 14 : Coeff b2 = S I0 . F13 F12 F11 F10 F9 F8 F7 F6 F5 F4 F3 F2 F1 F0

c12 Signed, Integer Bits = 0, Fractional Bits = 13, dec pt zero pad = 9 : Coeff c12 = S 0 . 000 000 000 F12 F11 F10 F9 F8 F7 F6 F5 F4 F3 F2 F1 F0

Padc Unsigned, Integer Bits = 10 : Padc U = I9 I8 I7 I6 I5 I4 I3 I2 I1 I0

Tadc Unsigned, Integer Bits =10 : Tadc U = I9 I8 I7 I6 I5 I4 I3 I2 I1 I0

NOTE: Negative coefficients are coded in 2’s complement notation.

3.2 Compensation

The 10-bit compensated pressure output, Pcomp, is calculated as follows:

Eqn. 1

Where: Padc is the 10-bit pressure ADC output of the MPL115A

Tadc is the 10-bit temperature ADC output of the MPL115A

a0 is the pressure offset coefficient

b1 is the pressure sensitivity coefficient

b2 is the temper at ure coefficient of of fset (TCO)

c12 is the temperature coefficient of sensitivity (TCS)

Pcomp will produce a value of 0 with an input pressure of 50 kPa and will produce a full-scale value of 1023 with an input pressure

of 115 kPa.

Eqn. 2

3.3 Evaluation Sequence, Arithmetic Circuits

The following is an example of the calculation for Pcomp, the compensated pressure output. Input values are in bold.

c12x2 = c12 * Tadc

a1 = b1 + c12x2

a1x1 = a1 * Padc

y1 = a0 + a1x1

a2x2 = b2 * Tadc

Pcomp = y1 + a2x2

This can be calculated as a succession of Multiply Accumulates (MACs) operations of the form y = a + b * x:

Pcomp a0 b1 c12 Tadc⋅+()Padc b2 Tadc⋅+⋅+=

Pressure (kPa) P=comp 115 50–

1023

---------------------- 50+⋅

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The polynomial can be evaluated (Equation 1) as a sequence of 3 MACs:

Please refer to Freescale application note AN3785 for more detailed notes on implementation.

3.4 I2C Device Read/Write Operations

All device read/write operations are memory mapped. Device actions e.g. “Start Conversions” are controlled by writing to the

appropriate memory address location.

•For I

2C the 7-bit Device Address (from Table 2) has a read/write toggle bit, where the least significa nt bit is ‘1’ for read

operations or ‘0’ for write operation s. The Device Address is 0xC0 for a Write and the Device Address is 0xC1 for a Rea d.

• The most significant bit in the Command tables below is not used and is don't care (X). In examples given it’s set to ‘0’.

Refer to Sensor I2C Setup and FAQ Application Note AN4481 for more information on I2C communication between the sensor

and host controller.

X = Don’t care

1 = The command byte needs to be paired with a 0x00 as part of the I2C exchange to complete the passing of Start Conversions.

Table 3. I2C Write Commands

Command Binary HEX(1)

Devices Address + Write bit 1100 0000 0xC0

Start Conversions X001 0010 0x12

Pcomp a0 b1 c12 Tadc⋅+()Padc b2 Tadc⋅+⋅+=

c12

Tadc

Padc

PComp

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The actions taken by the part in response to each command are as follows:

X = don’t care

These are MPL1 15A2 I2C commands to read coefficients, execute Pressure and Temperature conversions, and to read Pressure

and Temperature data. The sequence of the commands for the interaction is given as an examp le to operate the MPL115A2.

Utilizing this gathered data, an example of the calculating the Compensated Pressure reading is given in floating point notation.

I2C Commands (simplified for communication)

Device Address + write bit “To Write” = 0xC0

Device Address + read bit “To Read” = 0xC1

Command to Write “Convert Pressure and Temp erature” = 0x12

Command to Read “Pressure ADC High byte” = 0x00

Command to Read “Pressure ADC Low byte” = 0x01

Command to Read “Temperature ADC High byte” = 0x02

Command to Read “Temperature ADC Low byte” = 0x03

Command to Read “Coefficient data byte 1 High byte” = 0x04

Read Coefficients:

[0xC0], [0x04], [0xC1], [0x3E], [0xCE], [0xB3], [0xF9], [0xC5], [0x17], [0x33], [0xC8]

Figure 3. I2C Read Coefficient Datagram

Table 4. I2C Write Command Description

Command Action Taken

Start Conversions Wake main circuits. Start clock. Allow supply stabilization time. Select pressur e sensor input. Apply positive sensor

excitation and perform A to D conversion. Select temperature input. Perform A to D conversion. Load the Pressure and

Temperature registers with the result. Shut down main circuits and clock.

Table 5. I2C Read Command Description

Command Binary HEX(1)

Device Address + Read bit 1100 0001 0xC1

Read Pressure MSB X000 0000 0x00

Read Pressure LSB X000 0001 0x01

Read Temperature MSB X000 0010 0x02

Read Temperature LSB X000 0011 0x03

Read Coefficient data byte 1 X000 0100 0x04

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Figure 4. I2C S tart Conversion Datagram

Command to I2C Start Conversion, 0x12

Figure 5. I2C Read Results Data gram

a0 coefficient MSB =0x3E

a0 coefficient LSB =0xCE a0 coefficient =0x3ECE =2009.75

b1 coefficient MSB =0xB3

b1 coefficient LSB =0xF9 b1 coefficient =0xB3F9 =-2.37585

b2 coefficient MSB =0xC5

b2 coefficient LSB =0x17 b2 coefficient =0xC517 = -0.92047

c12 coeffici ent MSB =0x33

c12 coefficient LSB =0xC8 c12 coefficient =0x33C8 =0.000790

Pressure MSB =0x66

Pressure LSB =0x80 Pressure =0x6680 =0110 0110 1100 0000

=410 ADC counts

Temperature MSB =0x7E

Temperature LSB =0xC0 Temperature =0x7EC0 =0111 1110 1100 0000

=507 ADC counts

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3.5 Example of Pressure Compensated Calculation in Floating-point Notation

Pressure Compensation:

Using the evaluation sequence shown in Section 3.3:

4 Solder Recommendations

1. Use SAC solder alloy (i.e., Sn-Ag-Cu) with a melting point of about 217°C. It is recommended to use SAC305

(i.e., Sn-3.0 wt.% Ag-0.5 wt.% Cu).

2. Reflow

• Ramp up rate: 2 to 3°C/s.

• Preheat flat (soak): 110 to 130s.

• Reflow peak temperature: 250°C to 260°C (depends on exact SAC alloy composition).

• Time above 217°C: 40 to 90s (depends on board type, thermal mass of the board/quantities in the reflow).

• Ramp down: 5 to 6°C/s.

• Using an inert reflow environment (with O2 level about 5 to 15 ppm).

a0 coefficient =2009.75

b1 coefficient =-2.37585

b2 coefficient =-0.92047

c12 coefficient =0.000790

Pressure =410 ADC counts

Temperature =507 ADC counts

c12x2 = c12 * Tadc = 0.000790 * 507 = 0.40053

a1 = b1 + c12x2 = -2.37585 + 0.40053 = -1.97532

a1x1 = a1 * Padc = -1.97532 * 410 = -809.8812

y1 = a0 + a1x1 = 2009.75 + (-809.8812) = 1199.8688

a2x2 = b2 * Tadc = -0.92047 * 507 = -466.67829

PComp = y1 + a2x2 = 1199.8688 + (-466.67829) = 733.19051

Pcomp a0 b1 c12 Tadc⋅+()Padc b c()+⋅+=

Pressure (kPa) P=comp 115 50–

1023

---------------------- 50+⋅

733.19=115 50–

1023

---------------------- 50+

⋅

96.59kPa=

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NOTE: The stress level and signal offset of the device also depends on the board type, board core material, board thickness

and metal finishing of the board.

Please refer to Freescale application note AN3150, Soldering Recommendations for Pressure Sensor Devices for any additional

information.

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5 Handling Recommendations

It is recommended to handle the MPL115A pressure sensor with a vacuum pick and place tool. Sharp objects utilized to move

the MPL115A pressure sensor increase the possibility of damage via a foreig n object/tool into the small exposed port.

The sensor die is sensitive to light exposure. Direct light exposure through the port hole can lead to varied accuracy of pressure

measurement. Avoid such exposure to the port during normal operation.

Please note that the Pin 1 designator is on the bottom of the package. Do not use the port as a orientation reference in production.

6 Soldering/Landing Pad Information

The LGA package is compliant with the RoHS standard. It is recommended to use a no-clean solder paste to reduce cleaning

exposure to high pressure and chemical agents that can damage or reduce life span of the Pressure sensing element.

Figure 6. MPL115A2 Recommended PCB Lan din g Pattern

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7 Tape and Reel Specifications

Figure 7. LGA (3 x 5) Embossed Carrier Tape Dimensions

Figure 8. Device Orientation in Chip Carrier

(I) Measured from centerline of sprocket hole to

centerline of pocket.

(II) Cumulative tolerance of 10 sprocket holes is

±0.20.

(III) Measured from centerline of sprocket hole to

centerline of pocket.

(IV) Other material available.

Dimensions are in millimeters.

Ao 3.35 ± 0.10

Bo 5.35 ± 0.10

Ko 1.20 ± 0.10

F 5.50 ± 0.1 0

P1 8.00 ± 0.10

W 12.00 ± 0.10

Pin 1 Index Area

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PACKAGE DIMENSIONS

CASE 2015-02

ISSUE A

LGA PACKAGE

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Table 6. Revision History

Revision

number Revision

date Description of changes

8 06/2012 • Updated graphic on page 1, Section 2.2 Operating Characteristics: Ref 7: Conversion Time:

changed Typ from 3.0 to 1.6, Section 3.0 Overview of Functions/Operation: Reading Coefficient

Data deleted statement that reading of coefficients may be executed only once, Table 2: added

Size (bits) column in table, added new Section 3.4 I2C De vice Read/Write Operations

9 10/2012 • Changed Example Binary format definitions b1 signed F rom: 7 To: 13, added F11 to Coeff b1, b2

and c12 on page 6.

• Removed MPL115A2T2 from ordering table.

Document Number: MPL115A2

Rev. 9

02/2013

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