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Freescale Semiconductor
Technical Data
±2g/±4g/±8g Three Axis Low-g
Digital Output Accelerometer
The MMA7455L is a Digital Output (I
capacitive micromachined accelerometer featuring signal conditioning, a low
pass filter, temperature compensation, self-test, configurable to detect 0g
through interrupt pins (INT1 or INT2), and pulse detect for quick motion
detection. 0g offset and sensitivity are factory set and require no external
devices. The 0g offset can be customer calibrated using assigned 0g registers
and g-Select which allows for command selection for 3 acceleration ranges
(2g/4g/8g). The MMA7455L includes a Standby Mode that makes it ideal for
handheld battery powered electronics.
Features
2
•
Digital Output (I
C/SPI)
•
3mm x 5mm x 1mm LGA-14 Package
•
Self-Test for Z-Axis
•
Low Voltage Operation: 2.4 V – 3.6 V
•
User Assigned Registers for Offset Calibration
•
Programmable Threshold Interrupt Output
•
Level Detection for Motion Recognition (Shock, Vibration, Freefall)
•
Pulse Detection for Single or Double Pulse Recognition
•
Sensitivity (64 LSB/g @ 2g and @ 8g in 10-Bit Mode)
•
Selectable Sensitivity (±2g, ±4g, ±8g) for 8-bit Mode
•
Robust Design, High Shocks Survivability (5,000g)
•
RoHS Compliant
•
Environmentally Preferred Product
•
Low Cost
Typical Applications
•
Cell Phone/PMP/PDA: Image Stability, Text Scroll, Motion Dialing,
Tap to Mute
•
HDD: Freefall Detection
•
Laptop PC: Freefall Detection, Anti-Theft
•
Pedometer
•
Motion Sensing, Event Recorder
ORDERING INFORMATION
Part Number
Temperature Range
MMA7455LT
–40 to +85°C
MMA7455LR1
–40 to +85°C
MMA7455LR2
–40 to +85°C
This document contains certain information on a new product.
Specifications and information herein are subject to change without notice.
© Freescale Semiconductor, Inc., 2007-2009. All rights reserved.
2
C/SPI), low power, low profile
Package
Shipping
LGA-14
Tray
LGA-14
7" Tape & Reel
LGA-14
13" Tape & Reel
Document Number: MMA7455L
Rev 10, 12/2009
MMA7455L
MMA7455L: XYZ-AXIS
ACCELEROMETER
±2g/±4g/±8g
Bottom View
14 LEAD
LGA
CASE 1977-01
Top View
DVDD_IO
GND
N/C
IADDR0
GND
AVDD
Figure 1. Pin Connections
SDA/SDI/SDO
SDO
N/C
N/C
INT2
INT1/DRDY
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Related Manuals for Freescale Semiconductor MMA7455L
Summary of Contents for Freescale Semiconductor MMA7455L
- Page 1 The 0g offset can be customer calibrated using assigned 0g registers ACCELEROMETER and g-Select which allows for command selection for 3 acceleration ranges ±2g/±4g/±8g (2g/4g/8g). The MMA7455L includes a Standby Mode that makes it ideal for handheld battery powered electronics. Features •...
-
Page 2: Table Of Contents
SPI Slave Interface ..............................18 BASIC CONNECTIONS ................................19 Pin Descriptions ................................19 Recommended PCB Layout for Interfacing Accelerometer to Microcontroller .............19 REGISTER DEFINITIONS .................................21 SOLDERING AND MOUNTING GUIDELINES FOR THE LGA ACCELEROMETER SENSOR TO A PC BOARD ....29 MMA7455L Sensors Freescale Semiconductor... - Page 3 Single Byte Read - The Master is reading one address from the MMA7455L ........17 Multiple Bytes Read - The Master is reading multiple sequential registers from the MMA7455L ..... . . 17 Single Byte Write - The Master (MCU) is writing to a single register of the MMA7455L .
- Page 4 Acceleration vs. Output (8-bit data) ..............28 MMA7455L...
-
Page 5: Pin Descriptions
<$1D= 0001 1101> bit 0 is V on pin 4 <$1C=0001 1100> bit 0 is GND on pin 4. If the pin is programmed it cannot be left NC. Figure 2. Simplified Accelerometer Functional Block Diagram MMA7455L Sensors Freescale Semiconductor... -
Page 6: Electro Static Discharge (Esd)
A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. MMA7455L Sensors... - Page 7 Self-Test Response Time — — Sensing Element Resonant Frequency — — GCELLXY — — GCELLZ Nonlinearity (2 g range) — Cross Axis Sensitivity — 1. It is recommended to tie the analog and digital supply voltages together. MMA7455L Sensors Freescale Semiconductor...
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Page 8: Principle Of Operation
The ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the differ- ence between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a digital output that is proportional to acceleration. Acceleration Figure 3. Simplified Transducer Physical Model MMA7455L Sensors Freescale Semiconductor... -
Page 9: Features
The g-Select feature enables the selection between 3 acceleration ranges for measurement. Depending on the values in the Mode control register ($16), the MMA7455L’s internal gain will be changed allowing it to function with a 2g, 4g or 8g measurement sensitivity. -
Page 10: Level Detection
LDTH[7:0]: Level detection threshold value. If THOPT bit in Detection Control Register is “0”, it is unsigned 7 bits value and LDTH[7] should be “0”. If THOPT bit is “1”, it is signed 8 bits value. MMA7455L Sensors Freescale Semiconductor... -
Page 11: Threshold Detection For Motion And Freefall Conditions
Absolute: ||X|| <Threshold AND ||Y|| < Threshold AND ||Z||< Threshold Reg $18 THOPT=0; Reg 19 LDPL=1, Set Threshold to +/-0.5g, which is 7 counts (16 counts/g). Set register $1A LDTH = $07. TH = $07 TH = $F9 MMA7455L Sensors Freescale Semiconductor... -
Page 12: Pulse Detection
$1B: Pulse Detection Threshold Limit Value (Read/Write) Reg $1B PDTH[7] PDTH[6] PDTH[5] PDTH[4] PDTH[3] PDTH[2] PDTH[1] PDTH[0] Function Default $1C: Pulse Duration Value (Read/Write) Reg $1C PD[7] PD[6] PD[5] PD[4] PD[3] PD[2] PD[1] PD[0] Function Default MMA7455L Sensors Freescale Semiconductor... -
Page 13: Case 2: Freefall Detection: X And Y And Z < Pulse Threshold For Time > Latency Time
Reg $1B PDTH[7] PDTH[6] PDTH[5] PDTH[4] PDTH[3] PDTH[2] PDTH[1] PDTH[0] Function Default $1D: Latency Time Value (Read/Write) Reg $1D LT[7] LT[6] LT[5] LT[4] LT[3] LT[2] LT[1] LT[0] Function Default Figure 5. Freefall Detection in Pulse Mode MMA7455L Sensors Freescale Semiconductor... -
Page 14: Case 3: Double Pulse Detection: X Or Y Or Z > Threshold For Pulse Duration1 < Pdtime1, Latency Time
*Note there is up to 1.6ms delay on the interrupt sign al Time Double Pulse Detection ($19 PDPL=0 indicating motion detection) Time Window for 2 pulse $1E TW>0 indicating double pulse Figure 6. Double Pulse Detection MMA7455L Sensors Freescale Semiconductor... -
Page 15: Assigning, Clearing & Detecting Interrupts
After interrupt has triggered due to a detection, the interrupt pin (INT1 or INT2) need to be cleared by writing a logic 1. Then the interrupt pin should be enabled to trigger the next detection by setting it to a logic 0. This example is to show how to reset the interrupt flags void ClearIntLatch(void) IIC_ByteWrite(INTRST, 0x03); IIC_ByteWrite(INTRST, 0x00); MMA7455L Sensors Freescale Semiconductor... -
Page 16: Detecting Interrupts
MMA7455L sends an acknowledgement. The Master (or MCU) transmits a repeated start condition (SR) and then addresses the MMA7455L ($1D) with the R/W bit set to “1” for a read from the previously selected register. The Slave then acknowledges and transmits the data from the requested register. -
Page 17: Single Byte Read - The Master Is Reading One Address From The Mma7455L
MMA7455L sends an acknowledgement that it has received the data. Since this transmission is com- plete, the Master transmits a stop condition (SP) to the data transfer. The data sent to the MMA7455L is now stored in the ap- propriate register. -
Page 18: Spi Slave Interface
SPI Write Operation In order to write to one of the 8-bit registers, an 8-bit write command must be sent to the MMA7455L. The write command consists of an MSB (0=read, 1=write) to indicate writing to the MMA7455L register, followed by a 6-bit address and 1 don’t care bit. -
Page 19: Basic Connections
Data Input (SDI), 3-wire interface Input/ Serial Data Output (SDO) Output SCL/SPC Input C Serial Clock (SCL), SPI Serial Clock (SPC) Recommended PCB Layout for Interfacing Accelerometer to Microcontroller Figure 15. I C Connection to MCU MMA7455L Sensors Freescale Semiconductor... - Page 20 Any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency (sampling frequency). This will prevent aliasing errors. Physical distance of the two GND pins (Pin 2 and Pin 5) tied together should be at the shortest distance. MMA7455L Sensors Freescale Semiconductor...
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Page 21: Register Definitions
XOUT [3] XOUT [2] XOUT [1] XOUT[0] Function Default Signed byte data (2’s complement): 0g = 10’h000 Reading low byte XOUTL latches high byte XOUTH to allow 10-bit reads. XOUTH should be read directly following XOUTL read. MMA7455L Sensors Freescale Semiconductor... -
Page 22: 01: 10Bits Output Value X Msb (Read Only)
Signed byte data (2’s complement): 0g = 8’h00 $07: 8bits Output Value Y (Read only) YOUT[7] YOUT [6] YOUT [5] YOUT [4] YOUT [3] YOUT [2] YOUT [1] YOUT [0] Function Default Signed byte data (2’s complement): 0g = 8’h00 MMA7455L Sensors Freescale Semiconductor... -
Page 23: 08: 8Bits Output Value Z (Read Only)
1: I C is disabled. DVAD[6:0]: I C device address $0E: User Information (Read Only: Optional) UI[7] UI[6] UI[5] UI[4] UI[3] UI[2] UI[1] UI[0] Function 0/OTP 0/OTP 0/OTP 0/OTP 0/OTP 0/OTP 0/OTP 0/OTP Default UI2[7:0]: User information MMA7455L Sensors Freescale Semiconductor... -
Page 24: Who Am I" Value (Read Only: Optional)
Signed byte data (2’s complement): User level offset trim value for Y-axis YOFF[10] YOFF[9] YOFF[8] Weight* Polarity 256 LSB 128 LSB *Bit weight is for 2g 8-bit data output. Typical value for reference only. Variation is specified in “Electrical Characteristics” section. MMA7455L Sensors Freescale Semiconductor... -
Page 25: 14: Offset Drift Z Lsb (Read/Write)
00: Standby Mode 1: Data ready status is not output to INT1/DRDY PIN Table 11. Configuring the Mode using Register $16 with MODE[1:0] bits MODE [1:0] Function Standby Mode Measurement Mode Level Detection Mode Pulse Detection Mode MMA7455L Sensors Freescale Semiconductor... -
Page 26: 17: Interrupt Latch Reset (Read/Write)
1: Level detection polarity is negative detecting condition is 1: Pulse detection polarity is negative and detecting condition AND 3 axes. is AND 3 axes. DRVO 0: Standard drive strength on SDA/SDO pin 1: Strong drive strength on SDA/SDO pin MMA7455L Sensors Freescale Semiconductor... -
Page 27: Pulse Detection Threshold Limit Value (Read/Write)
$1E: Time Window for 2nd Pulse Value (Read/Write) TW[7] TW[6] TW[5] TW[4] TW[3] TW[2] TW[1] TW[0] Function Default Min: TW[7:0] = 8’h01 = 1 ms (Single pulse detection) Max: TW[7:0] = 8’hFF = 255 ms 1 LSB = 1 ms MMA7455L Sensors Freescale Semiconductor... -
Page 28: Sensing Direction And Output Response At 2G Mode
* When positioned as shown, the Earth’s gravity will result in a positive 1g output. Figure 17. Sensing Direction and Output Response at 2g Mode Table 13. Acceleration vs. Output (8-bit data) FS Mode Acceleration Output 2g Mode 4g Mode 8g Mode MMA7455L Sensors Freescale Semiconductor... -
Page 29: Soldering And Mounting Guidelines For The Lga Accelerometer Sensor To A Pc Board
These guideline are for soldering and mounting the LGA package inertial sensors to printed circuit boards (PCBs). The purpose is to minimize the stress on the package after board mounting. The MMA7455L digital output accelerometer uses the Land Grid Array (LGA) package platform. This section describes suggested methods of soldering these devices to the PC board for con- sumer applications. -
Page 30: Recommended Pcb Land Pad, Solder Mask, And Signal Trace Near Package Design
0.8 mm Wider trace Cu: 0.9 x 0.6 mm sq. SM opening = PCB land pad + 0.1mm = 1.0 x 0.7mm sq. Figure 21. Recommended PCB Land Pad, Solder Mask, and Signal Trace Near Package Design MMA7455L Sensors Freescale Semiconductor... - Page 31 Freescale LGA sensors are compliant with Restrictions on Hazardous Substances (RoHS), having halide free molding compound (green) and lead-free terminations. These terminations are compatible with tin-lead (Sn-Pb) as well as tin-silver-copper (Sn-Ag-Cu) solder paste soldering processes. Reflow profiles applicable to those processes can be used successfully for solder- ing the devices. MMA7455L Sensors Freescale Semiconductor...
- Page 32 -0.01 0.01 0.02 Zsens_%/DegreeC_-40to85 Zoff_mg/degreeC_-40to85 Target Targ et -0.03 -0.02 -0.01 0.01 0.02 0.03 Figure 23. MMA7455L Temperature Coefficient of Offset (TCO) and Temperature Coefficient of Sensitivity (TCS) Distribution Charts Figure 24. MMA7455L Current Distribution Charts MMA7455L Sensors Freescale Semiconductor...
- Page 33 PACKAGE DIMENSIONS CASE 1977-01 ISSUE A 14-LEAD LGA MMA7455L Sensors Freescale Semiconductor...
- Page 34 PACKAGE DIMENSIONS CASE 1977-01 ISSUE A 14-LEAD LGA MMA7455L Sensors Freescale Semiconductor...
- Page 35 Freescale Semiconductor assume any liability arising out of the application or use of any Japan: product or circuit, and specifically disclaims any and all liability, including without Freescale Semiconductor Japan Ltd.
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