Freescale公司的MMA845xQ系列是智能低功耗三轴容性微机械加速度计,具有12位分辨率,电源电压1.95V-3.6V,接口电压1.6V-3.6V,动态可选择满刻度+/-2g/+/-4g/+/-8g,输出数据速率(ODR)为1.56 Hz 到800 Hz,12位和8位数字输出,I2C数字输出接口,电流消耗6uA-160uA,主要用于电子罗盘,静态方向检测,笔记本,电子书等跌落检测,实时方向检测和工作分析,手持设备运动检测,震动和振动监视和用户接口.本文介绍了MMA845xQ系列主要特性和方框图,应用框图以及MMA845xQ加速计开发套件LFSTBEB845x电路图与MMA8451/2/3Q应用电路图.
The MMA8452Q is a smart low-power, three-axis, capacitive micromachined accelerometer with 12 bits of resolution. This accelerometer is packed with embedded functions with flexible user programmable options, configurable to two interrupt pins. Embedded interrupt functions allow for overall power savings relieving the host processor from continuously polling data.
The MMA8452Q has user selectable full scales of +/-2g/+/-4g/+/-8g with high-pass filter filtered data as well as non-filtered data available real-time. The device can be configured to generate inertial wakeup interrupt signals from any combination of the configurable embedded functions allowing the MMA8452Q to monitor events and remain in a low power mode during periods of inactivity. The MMA8452Q is available in a 3 mm by 3 mm by 1 mm QFN package.

MMA845xQ系列主要特性:
. 1.95V to 3.6V supply voltage
. 1.6V to 3.6V interface voltage
. +/-2g/+/-4g/+/-8g dynamically selectable full-scale
. Output Data Rates (ODR) from 1.56 Hz to 800 Hz
. 99 ug/√Hz noise
. 12-bit and 8-bit digital output
. I2C digital output interface
. Two programmable interrupt pins for six interrupt sources
. Three embedded channels of motion detection
. Freefall or Motion Detection: 1 channel
. Pulse Detection: 1 channel
. Transient Detection: 1 channel
. Orientation (Portrait/Landscape) detection with set hysteresis
. Automatic ODR change for Auto-WAKE and return to SLEEP
. High-Pass Filter Data available real-time
. Self-Test
. RoHS compliant
. Current Consumption: 6uA-165 uA

MMA845xQ系列典型应用:
. eCompass applications
. Static orientation detection (Portrait/Landscape, Up/Down, Left/Right, Back/Front position identification)
. Notebook, eReader and Laptop Tumble and Freefall Detection
. Real-time orientation detection (virtual reality and gaming 3D user position feedback)
. Real-time activity analysis (pedometer step counting, freefall drop detection for HDD, dead-reckoning GPS backup)
. Motion detection for portable product power saving (Auto-SLEEP and Auto-WAKE for cell phone, PDA, GPS, gaming)
. Shock and vibration monitoring (mechatronic compensation, shipping and warranty usage logging)
. User interface (menu scrolling by orientation change, pulse detection for button replacement)

图1.MMA845xQ系列框图

图2.MMA845xQ系列应用框图

MMA845xQ加速计开发套件
The Freescale MMA845xQ sensor toolbox accelerometer kit provides hardware and software for development and demonstration of the MMA845xQ family of accelerometers.

MMA845xQ加速计开发套件包括:
The kit includes the following:
• MMA845xQ evaluation board
• MMA8451Q accelerometer daughter board
• MMA8452Q accelerometer daughter board
• MMA8453Q accelerometer daughter board
The kit requires the LFSTBUSB USB-interface board to attach the kit to a personal computer. If you already have the RD3924MM450Q Sensor Toolbox, for the MMA8450Q accelerometer, the USB board is in that kit.
The MMA845xQ kit’s part number is LFSTBEB845x and the USB-interface board’s part number is LFSTBUSB.

图3.MMA845xQ加速计开发套件外形图


图4.LFSTBEB845x电路图(1)

图5.LFSTBEB845x电路图(2)


图6.LFSTBEB845x开发板布局图

图7.MMA8451Q电路图

图8.MMA8452Q电路图

图9.MMA8453Q电路图