Freescale Semiconductor
Data Sheet: Technical Data
Document Number: MPL115A2
Rev. 9, 02/2013
Miniature I
2
C Digital Barometer
The MPL115A2 is an absolute pressure sensor with a digital I
2
C 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
during 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 I
2
C 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.
MPL115A2
50 to 115 kPa
MPL115A2
5.0 mm x 3.0 mm x 1.2 mm
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
2
C Interface (operates up to 400 kHz)
7-bit I
2
C address = 0x60
Monotonic pressure and temperature data outputs
Surface mount RoHS compliant package
VDD
CAP
GND
SHDN
Top View
1
2
3
4
8
7
6
5
SCL
SDA
NC
RST
Pin Connections
Application Examples
•
•
•
•
•
•
•
Barometry (portable and desktop)
Altimeters
Weather stations
Hard-disk drives (HDD)
Industrial equipment
Health monitoring
Air control systems
ORDERING INFORMATION
Device Name
MPL115A2
MPL115A2T1
Package Options
Tray
Tape & Reel (1000)
Case No.
2015
2015
# of Ports
None
•
•
Single
Dual
Gauge
Pressure Type
Differential
Absolute
•
•
Digital
Interface
I
2
C
I
2
C
© 2009-2013 Freescale Semiconductor, Inc. All rights reserved.
1
Block Diagram and Pin Descriptions
VDD
1
μF
VDD
ADDR
Coefficient
Storage
Diff
Amp
MUX
ADC
ADDR
CAP
CAP
1
μF
ADDR
SHDN
ADDR
Pressure
SHDN
ADDR
Temperature
Temp
Sensor
I
2
C
Interface
4.7 k
SCL
SCL
4.7 k
μC
Microcontroller
SDA
RST
SDA
RST
GND
GND
Figure 1. Block Diagram and Pin Connections
Table 1. Pin Description
Pin
1
2
3
4
Name
VDD
CAP
GND
SHDN
Function
VDD Power Supply Connection: VDD range is 2.375V to 5.5V.
1
μF
connected to ground.
Ground
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.
Reset: Connect to ground to disable I
2
C communications.
NC: No connection
SDA: Serial data I/O line
I
2
C Serial Clock Input.
5
6
7
8
RST
NC
SDA
(1)
SCL
(1)
1. Use 4.7k pullup resistors for I
2
C communication.
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2.1
Mechanical and Electrical Specifications
Maximum Ratings
V
DD
..................................................................................................................... -0.3 V to +5.5 V
SHDN, RST, SDA, SCL ...............................................................................-0.3 V to V
DD
+0.3 V
Operating Temperature Range .......................................................................... -40°C to +105°C
Storage Temperature Range ............................................................................. -40°C to +125°C
Overpressure................................................................................................................ 1000 kPa
Voltage (with respect to GND unless otherwise noted)
2.2
Ref
1
2
Operating Characteristics
Parameters
Operating Supply Voltage
Supply Current
Symbol
V
DD
I
DD
Shutdown (SHDN = GND)
Standby
Average – at one measurement per second
Conditions
Min
2.375
—
—
—
Typ
3.3
—
3.5
5
Max
5.5
1
10
6
Units
V
μA
μA
μA
V
DD
=
2.375 V to 5.5 V, T
A
= -40°C to +105°C, unless otherwise noted. Typical values are at V
DD
= 3.3 V, T
A
= +25°C.
Pressure Sensor
3
4
5
6
Range
Resolution
Accuracy
Power Supply Rejection
-20ºC to 85ºC
Typical operating circuit at DC
100 mV p-p 217 Hz square wave plus 100 mV
pseudo random noise with 10 MHz bandwidth
7
Conversion Time
(Start Pressure and Temperature
Conversion)
Wakeup Time
tc
Time between start convert command and
data available in the Pressure and
Temperature registers
Time between leaving Shutdown mode
(SHDN goes high) and communicating with
the device to issue a command or read data.
—
50
—
—
—
0.15
—
0.1
0.1
1.6
115
—
±1
—
—
3
kPa
kPa
kPa
kPa/V
kPa
ms
8
tw
—
3
5
ms
I
2
C I/O Stages: SCL, SDA
9
10
11
SCL Clock Frequency
Low Level Input Voltage
High Level Input Voltage
f
SCL
VIL
VIH
—
—
0.7VDD
—
—
—
400
0.3VDD
—
kHz
V
V
I
2
C Outputs: SDA
12
Data Setup Time
t
SU
Setup time from command receipt to ready to
transmit
0
—
0.4
s
I
2
C 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
3
Overview of Functions/Operation
Initial
powerup
Reading
coefficient data
Data conversion
Compensated
pressure reading
Shutdown
Figure 2. Sequence Flow Chart
The MPL115A interfaces to a host (or system) microcontroller in the user’s application. All communications are via I
2
C. A typical
usage sequence is as follows:
Initial Power-up
All circuit elements are active. I
2
C 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 local 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 pressure 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 within 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.
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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.
Table 2. Device Memory Map
Address
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
Name
Padc_MSB
Padc_LSB
Tadc_MSB
Tacd_LSB
a0_MSB
a0_LSB
b1_MSB
b1_LSB
b2_MSB
b2_LSB
c12_MSB
c12_LSB
Reserved*
Reserved*
Reserved*
Reserved*
Reserved
Reserved
CONVERT
Description
10-bit Pressure ADC output value MSB
10-bit Pressure ADC output value LSB
10-bit Temperature ADC output value MSB
10-bit Temperature ADC output value LSB
a0 coefficient MSB
a0 coefficient LSB
b1 coefficient MSB
b1 coefficient LSB
b2 coefficient MSB
b2 coefficient LSB
c12 coefficient MSB
c12 coefficient LSB
—
—
—
—
—
—
Start Pressure and Temperature Conversion
Size (bits)
8
2
8
2
8
8
8
8
8
8
8
8
—
—
—
—
—
—
—
*These registers are set to 0x00. These are reserved, and were previously utilized as Coefficient values, c11 and
c22, which were always 0x00.
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] = [c12
b13
, c12
b12
, c12
b11
, c12
b10
, c12
b9
, c12
b8
, c12
b7
, c12
b6
]
c12 LS byte = c12[5:0] & “00” = [c12
b5
, c12
b4
, c12
b3
, c12
b2
, c12
b1
, c12
b0
, 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.
Pressure, Temperature and Compensation Coefficient Specifications
a0
Total Bits
Sign Bits
Integer Bits
Fractional Bits
dec pt zero pad
16
1
12
3
0
b1
16
1
2
13
0
b2
16
1
1
14
0
c12
14
1
0
13
9
Padc
10
0
10
0
0
Tadc
10
0
10
0
0
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