MPL115A2_技术文档

Document Number: MPL115A2

Rev. 9, 02/2013

Freescale Semiconductor

Data Sheet: Technical Data

Miniature I²C Digital Barometer

MPL115A2

The MPL115A2 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 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.

50 to 115 kPa

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.

MPL115A2

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

precision, and digital output optimize it for barometric measurement

applications.

5.0 mm x 3.0 mm x 1.2 mm

Top View

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

1

2

3

4

8

7

6

5

SCL

SDA

NC

VDD

CAP

•

GND

2.375V to 5.5V supply

RST

SHDN

Integrated ADC

I²C Interface (operates up to 400 kHz)

7-bit I²C address = 0x60

Pin Connections

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

# of Ports

Pressure Type

Digital

Interface

Device Name

Package Options

Case No.

None

Single

Dual

Gauge

Differential Absolute

MPL115A2

Tray

2015

•

I²C

MPL115A2T1

Tape & Reel (1000)

1

Block Diagram and Pin Descriptions

1 μF

VDD

ADDR

CAP

1 μF

ADDR

Coefficient

Storage

ADDR

Diff

Amp

SHDN

ADDR

Pressure

ADC

ADDR Temperature

Temp

Sensor

4.7 k

SCL

μC

Microcontroller

4.7 k

I²C

Interface

SDA

RST

GND

Figure 1. Block Diagram and Pin Connections

Table 1. Pin Description

Name

Function

1

VDD

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

2

3

CAP

GND

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.

4

SHDN

Reset: Connect to ground to disable I²C communications.

NC: No connection

5

6

7

8

RST

NC

SDA⁽¹⁾

SCL⁽¹⁾

SDA: Serial data I/O line

I²C Serial Clock Input.

1. Use 4.7k pullup resistors for I²C communication.

MPL115A2

2

Sensors

Freescale Semiconductor, Inc.

2

Mechanical and Electrical Specifications

2.1

Maximum Ratings

Voltage (with respect to GND unless otherwise noted)

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

2.2

Operating Characteristics

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.

Ref

1

Parameters

Operating Supply Voltage

Supply Current

Symbol

V_DD

Conditions

Min

2.375

—

Typ

3.3

—

Max

5.5

1

Units

V

2

Shutdown (SHDN = GND)

Standby

μA

I_DD

—

3.5

5

10

6

μA

Average – at one measurement per second

—

μA

Pressure Sensor

3

4

5

6

Range

50

—

0.15

—

115

—

kPa

Resolution

Accuracy

-20ºC to 85ºC

±1

—

kPa

Power Supply Rejection

Typical operating circuit at DC

0.1

kPa/V

kPa

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

pseudo random noise with 10 MHz bandwidth

—

7

8

Conversion Time

(Start Pressure and Temperature

Conversion)

Time between start convert command and

data available in the Pressure and

Temperature registers

—

1.6

3

5

ms

tc

Wakeup Time

Time between leaving Shutdown mode

(SHDN goes high) and communicating with

the device to issue a command or read data.

tw

I²C I/O Stages: SCL, SDA

SCL Clock Frequency

9

—

400

kHz

V

f_SCL

VIL

10 Low Level Input Voltage

11 High Level Input Voltage

0.3V

DD

0.7V

—

V

VIH

DD

I²C Outputs: SDA

12 Data Setup Time

Setup time from command receipt to ready to

transmit

0

—

0.4

s

t_SU

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

Sensors

Freescale Semiconductor, Inc.

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 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 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.

MPL115A2

Sensors

4

Freescale Semiconductor, Inc.

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

Description

Size (bits)

Padc_MSB

Padc_LSB

Tadc_MSB

Tacd_LSB

a0_MSB

10-bit Pressure ADC output value MSB

8

2

10-bit Pressure ADC output value LSB

10-bit Temperature ADC output value MSB

8

10-bit Temperature ADC output value LSB

2

a0 coefficient MSB

8

a0_LSB

a0 coefficient LSB

8

b1_MSB

b1 coefficient MSB

8

b1_LSB

b1 coefficient LSB

8

b2_MSB

b2 coefficient MSB

8

b2_LSB

b2 coefficient LSB

8

c12_MSB

c12_LSB

Reserved*

Reserved

CONVERT

c12 coefficient MSB

8

c12 coefficient LSB

8

—

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.

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

16

1

b1

16

1

b2

16

1

c12

14

1

Padc

10

0

Tadc

10

0

Total Bits

Sign Bits

12

3

2

1

0

10

0

10

0

Integer Bits

Fractional Bits

dec pt zero pad

13

0

14

0

13

9

0

MPL115A2

Sensors

Freescale Semiconductor, Inc.

5

Example Binary Format Definitions:

a0 Signed, Integer Bits = 12, Fractional Bits = 3 :

b1 Signed, Integer Bits = 2, Fractional Bits = 13 :

b2 Signed, Integer Bits = 1, Fractional Bits = 14 :

Coeff a0 = S I₁₁I₁₀I₉I₈I₇I₆I₅I₄I₃I₂I₁I₀. F₂F₁F₀

Coeff b1 = S I₁I₀. F₁₂F₁₁F₁₀F₉F₈F₇F₆F₅F₄F₃F₂F₁F₀

Coeff b2 = S I₀. F₁₃F₁₂F₁₁F₁₀F₉F₈F₇F₆F₅F₄F₃F₂F₁F₀

c12 Signed, Integer Bits = 0, Fractional Bits = 13, dec pt zero pad = 9 : Coeff c12 = S 0 . 000 000 000F₁₂F₁₁F₁₀F₉F₈F₇F₆F₅F₄F₃F₂F₁F₀

Padc Unsigned, Integer Bits = 10 :

Tadc Unsigned, Integer Bits =10 :

Padc U = I₉I₈I₇I₆I₅I₄I₃I₂I₁I₀

Tadc U = I₉I₈I₇I₆I₅I₄I₃I₂I₁I₀

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

3.2

Compensation

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

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

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 temperature coefficient of offset (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.

115 – 50

1023

----------------------

Pressure (kPa) = Pcomp ⋅

+ 50

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:

a

b

x

+

y

X

MPL115A2

6

Sensors

Freescale Semiconductor, Inc.

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

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

b1

c12

a1

Tadc

a0

y1

Padc

b2

y

PComp

Tadc

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

2

3.4

I C 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 I²C the 7-bit Device Address (from Table 2) has a read/write toggle bit, where the least significant bit is ‘1’ for read

operations or ‘0’ for write operations. The Device Address is 0xC0 for a Write and the Device Address is 0xC1 for a Read.

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.

Table 3. I²C Write Commands

HEX⁽¹⁾

Command

Devices Address + Write bit

Binary

1100 0000

X001 0010

0xC0

Start Conversions

0x12

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.

MPL115A2

Sensors

Freescale Semiconductor, Inc.

7

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

Table 4. I²C Write Command Description

Command

Action Taken

Wake main circuits. Start clock. Allow supply stabilization time. Select pressure 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.

Start Conversions

Table 5. I²C Read Command Description

HEX⁽¹⁾

Command

Binary

Device Address + Read bit

Read Pressure MSB

1100 0001

X000 0000

X000 0001

X000 0010

X000 0011

X000 0100

0xC1

0x00

0x01

0x02

0x03

0x04

Read Pressure LSB

Read Temperature MSB

Read Temperature LSB

Read Coefficient data byte 1

X = don’t care

These are MPL115A2 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 example 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 Temperature” = 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

MPL115A2

Sensors

8

Freescale Semiconductor, Inc.

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 coefficient MSB = 0x33

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

Figure 4. I²C Start Conversion Datagram

Command to I²C Start Conversion, 0x12

Figure 5. I²C Read Results Datagram

Pressure MSB

Pressure LSB

= 0x66

= 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

MPL115A2

Sensors

Freescale Semiconductor, Inc.

9

3.5

Example of Pressure Compensated Calculation in Floating-point Notation

a0 coefficient

b1 coefficient

b2 coefficient

c12 coefficient

=

2009.75

-2.37585

-0.92047

0.000790

Pressure

=

410 ADC counts

507 ADC counts

Temperature

Pressure Compensation:

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

Using the evaluation sequence shown in Section 3.3:

c12x2

a1

= c12 * Tadc

=

0.000790 * 507

= 0.40053

= b1 + c12x2 = -2.37585 + 0.40053

= a1 * Padc = -1.97532 * 410

= -1.97532

= -809.8812

= 1199.8688

= -466.67829

a1x1

y1

= a0 + a1x1 = 2009.75 + (-809.8812)

a2x2

= b2 * Tadc

= -0.92047 * 507

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

115 – 50

1023

----------------------

Pressure (kPa) = Pcomp ⋅

+ 50

= 96.59kPa

115 – 50

1023

----------------------

= 733.19 ⋅

+ 50

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 O₂level about 5 to 15 ppm).

MPL115A2

10

Sensors

Freescale Semiconductor, Inc.

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.

MPL115A2

Sensors

Freescale Semiconductor, Inc.

11

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 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.

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 Landing Pattern

MPL115A2

Sensors

12

Freescale Semiconductor, Inc.

7

Tape and Reel Specifications

(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

5.35 ± 0.10

1.20 ± 0.10

5.50 ± 0.10

8.00 ± 0.10

12.00 ± 0.10

Bo

Ko

F

P1

W

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

Pin 1 Index Area

Figure 8. Device Orientation in Chip Carrier

MPL115A2

13

Sensors

Freescale Semiconductor, Inc.

PACKAGE DIMENSIONS

CASE 2015-02

ISSUE A

LGA PACKAGE

MPL115A2

14

Sensors

Freescale Semiconductor, Inc.

Table 6. Revision History

Revision Revision

Description of changes

number

date

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 Device Read/Write Operations

9

10/2012

• Changed Example Binary format definitions b1 signed From: 7 To: 13, added F₁₁to Coeff b1, b2

and c12 on page 6.

• Removed MPL115A2T2 from ordering table.

MPL115A2

Sensors

Freescale Semiconductor, Inc.

15

Information in this document is provided solely to enable system and software

implementers to use Freescale products. There are no express or implied copyright

licenses granted hereunder to design or fabricate any integrated circuits based on the

information in this document.

How to Reach Us:

Home Page:

freescale.com

Web Support:

freescale.com/support

Freescale reserves the right to make changes without further notice to any products

herein. Freescale makes no warranty, representation, or guarantee regarding the

suitability of its products for any particular purpose, nor does Freescale 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 that may be provided in Freescale data sheets and/or

specifications 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. Freescale does not convey any

license under its patent rights nor the rights of others. Freescale sells products pursuant

to standard terms and conditions of sale, which can be found at the following address:

freescale.com/SalesTermsandConditions.

Freescale, the Freescale logo, AltiVec, C-5, CodeTest, CodeWarrior, ColdFire, C-Ware,

Energy Efficient Solutions logo, Kinetis, mobileGT, PowerQUICC, Processor Expert,

QorIQ, Qorivva, StarCore, Symphony, and VortiQa are trademarks of Freescale

Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. Airfast, BeeKit, BeeStack, ColdFire+,

CoreNet, Flexis, MagniV, MXC, Platform in a Package, QorIQ Qonverge, QUICC

Engine, Ready Play, SafeAssure, SMARTMOS, TurboLink, Vybrid, and Xtrinsic are

trademarks of Freescale Semiconductor, Inc. All other product or service names are

the property of their respective owners.

Document Number: MPL115A2

Rev. 9

02/2013


型号：	MPL115A2
厂家：	NXP
描述：	12C VERSION 输出元件传感器换能器
文件：	总16页 (文件大小：201K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MPL115A2 [NXP]

相关型号：

MPL115A2T1

MPL115A2T1

MPL115A2T2

MPL115A2_10

MPL115A2_13

MPL135

MPL135-0R4

MPL135-1R0

MPL135-1R5

MPL135-R22

MPL135-R47

MPL135-R56