FREESCALE MPL115A2

Pressure
Freescale Semiconductor
MPL115A2
Rev 5, 08/2009
Miniature I2C Digital Barometer
The MPL115A2 is an absolute pressure sensor with digital output for low cost
applications. A miniature 5 x 3 x 1.2 mm LGA package ideally suits it for portable
electronics and space constrained applications. Low current consumptions of
5 μA during Active mode and 1 μA during Shutdown (Sleep) mode target battery
and other low-power applications. A wide operating temperature range from -40°C
to +105°C fits demanding environmental requirements.
MPL115A2 employs a MEMS pressure sensor with a conditioning IC to provide
accurate pressure measurement from 50 to 115 kPa. An integrated ADC provides
digitized temperature and pressure sensor outputs via an I2C port. Calibration
Data is stored in internal ROM. Utilizing raw sensor output, 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
MPL115A2
50 to 115 kPa
Application Examples
•
•
•
•
•
•
•
Barometry (portable and desk-top)
Altimeters
Weather Stations
Hard Disk-Drives (HDD)
Industrial Equipment
Health Monitoring
Air Control Systems
• 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
• 2.375 V to 5.5 V Supply
• Integrated ADC
• I2C Interface
• Monotonic Pressure and Temperature Data Outputs
• Surface Mount RoHS Compliant Package
ORDERING INFORMATION
Device Name
MPL115A2T1
Package Options
Case No.
Tape & Reel
2015
# of Ports
None
Single
Pressure Type
Dual
Gauge
Differential
•
Absolute
Digital
Interface
•
I2 C
LGA PACKAGE
Pin Description
MPL115A2
5.0 mm X 3.0 mm X 1.2 mm MAX
VDD
CAP
1
2
8
7
SCL
SDA
GND
3
6
NC
SHDN
4
5
RST
PIN
NAME
1
VDD
VDD Power Supply Connection.
FUNCTION
2
CAP
External Capacitor
3
GND
Ground
4
SHDN
5
RST
Reset: Drive line low to disable I2C communications.
6
NC
NC: No connection.
7
SDA(1)
SDA: Serial data I/O line.
8
SCL(1)
I2C Serial Clock Input.
Shutdown (Sleep): Connect to GND to disable the device.
1. Use 4.7k pull-up resistors for I2C communication.
PIN CONNECTIONS
© Freescale Semiconductor, Inc., 2009. All rights reserved.
Pressure
Maximum Ratings
Voltage (with respect to GND unless otherwise noted)
VDD .............................................................................................................................. -0.3 V to +5.5 V
SCLK, CS, DIN, DOUT ................................................................................................. -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
Operating Characteristics
(VDD = 2.375 V to 5.5 V, TA = -40°C to +105°C, unless otherwise noted. Typical values are at V+ = 3.3 V, TA = +25°C.
Ref
Parameters
Symbol
1
Operating Supply Voltage
VDD
2
Supply Current
IDD
Conditions
Min
Typ
Max
Units
2.375
3.3
5.5
V
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
Time between start convert command and data
available in the Pressure register
—
0.6
0.7
ms
-40
—
105
ºC
7
Conversion Time
(Start Pressure Convert)
tcp
Temperature Sensor
8
Range
9
Conversion Time
(Start Temperature Convert)
tct
Time between start convert command and data
available in the Temperature register
—
0.6
0.7
ms
10
Conversion Time
(Start Both Convert)
tcb
Time between start convert command and data
available in the Pressure and Temperature
registers
—
0.8
1
ms
11
Resolution
Temperature ADC is 472 counts at 25ºC
—
-5.35
—
counts/ºC
I2C I/O Stages: SCL, SDA
12
SCL Clock Frequency
fSCL
—
—
400
KHz
13
Low Level Input Voltage
VIL
—
—
0.3VDD
V
14
High Level Input Voltage
VIH
0.7VDD
—
—
V
100
—
—
ns
I2C Outputs: SDA
15
Data Setup Time
tSU
Setup time from command receipt to ready to
transmit
I2C Addressing
MPL115A2 uses 7-bit addressing, does not acknowledge the general call address 0000000. Slave address has been set to 0x60 or 1100000.
MPL115A2
2
Sensors
Freescale Semiconductor
Pressure
1 μF
VDD
VDD
ADDR
Coefficient
Storage
CAP
CAP
ADDR
1 μF
ADDR
MUX
Diff
Amp
ADC
ADDR
Pressure
ADDR
Temperature
Temp
Sensor
SHDN
SHDN
4.7 k
I 2C
Interface
SCL
SCL
SDA
SDA
RST
RST
μC
4.7 k
Microcontroller
GND
GND
Figure 1. Block Diagram
Compensation
The pressure compensation for MPL115A2 is based on a 2-dimensional, second order polynomial.
The 10-bit compensated pressure output, Pcomp, is calculated as follows:
Pcomp = a0 + (b1 + c11*Padc + c12*Tadc) * Padc + (b2 + c22*Tadc) * Tadc
Where:
Padc is the 10-bit pressure output of the MPL115A2 ADC,
Tadc is the 10-bit temperature output of the MPL115A2 ADC,
a0 is the pressure offset coefficient,
b1 is the pressure sensitivity coefficient,
c11 is the pressure linearity (2nd order) coefficient,
c12 is the coefficient for temperature sensitivity coefficient (TCS),
b2 is the 1st order temperature offset coefficient (TCO),
c22 is the 2nd order temperature offset coefficient.
Ideally, 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.
MPL115A2
Sensors
Freescale Semiconductor
3
Pressure
Coefficient Bit-Width Specs
The table below specifies the initial coefficient bit-width specs for the compensation algorithm.
a0
b1
b2
c12
c11*
c22*
Total
Coeff.
Bits
Total Bits
16
16
16
14
11
11
84
Sign Bits
1
1
1
1
1
1
Integer Bits
12
2
1
0
0
0
Fractional Bits
4
13
14
13
11
10
dec pt zero pad
—
—
—
9
11
15
10-bit Output: Compensation Coefficient Specs
* Factory reserves the option to make these values = 0.
Example Binary Format Definitions:
1.
Sign = 0, Integer Bits = 8, Fractional Bits = 4 :
Coeff = S I7 I6 I5 I4 I3 I2 I1 I0 . F3 F2 F1 F0
2.
Sign = 1, Integer Bits = 4, Fractional Bits = 7 :
Coeff = S I3 I2 I1 I0 . F6 F5 F4 F3 F2 F1 F0
3.
Sign = 0, Integer Bits = 0, Fractional Bits = 6, dec pt zero pad = 2 : Coeff = S 0 . 0 0 F5 F4 F3 F2 F1 F0
4.
Sign = 0, Integer Bits = 0, Fractional Bits = 5, dec pt zero pad = 3 : Coeff = S 0 . 0 0 0 F4 F3 F2 F1 F0
NOTE: Negative coefficients (Sign = 1) are coded in 2’s complement notation.
Coefficient Address Map
Address
Coefficient
$04
a0 MS Byte
$05
a0 LS Byte
$06
b1 MS Byte
$07
b1 LS Byte
$08
b2 MS Byte
$09
b2 LS Byte
$0A
c12 MS Byte
$0B
c12 LS Byte
$0C
c11 MS Byte
$0D
c11 LS Byte
$0E
c22 MS Byte
$0F
c22 LS Byte
For coefficients with less than 16 bits, the lower lsbs are zero. For example, c11 is 11 bits and is stored into 2 bytes as follows:
c11 MS byte = c11[10:3] = [c11b10 , c11b9 , c11b8 , c11b7 , c11b6 , c11b5 , c11b4 , c11b3]
c11 LS byte = c11[2:0] & “00000” = [c11b2 , c11b1 , c11b0 , 0 , 0 , 0 , 0 , 0]
MPL115A2
4
Sensors
Freescale Semiconductor
Pressure
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).
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.
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 foreign 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.
MPL115A2
Sensors
Freescale Semiconductor
5
Pressure
PACKAGE DIMENSIONS
CASE 2015-02
ISSUE O
LGA PACKAGE
MPL115A2
6
Sensors
Freescale Semiconductor
Pressure
PACKAGE DIMENSIONS
CASE 2015-02
ISSUE O
LGA PACKAGE
MPL115A2
Sensors
Freescale Semiconductor
7
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MPL115A2
Rev. 5
08/2009
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