原标题：Freescale MMA8451Q智能低功耗三轴加速度计解决方案

　　freescale 公司的MMA8451Q是智能低功耗三轴容性微机械数字加速度计,具有14位分辨率,3x3x1mmQFN封装,电源电压1.95V-3.6V,接口电压1.6V-3.6V,动态可选择满刻度为 ±2g/±4g/±8g ,输出数据速率(ODR)从1.56 Hz 到800 Hz,噪音为99 μg/√Hz ,定流消耗6 μA – 165 μA,主要用在电子罗盘,静态位置检测,笔记本电脑,电子书,实时位置检测,手持产品运动检测,震动和振动监测,用户接口等.本文介绍了MMA8451Q主要特性,框图,应用框图以及MMA845X系列传感器加速计工具箱LFSTBEB845X主要特性,电路图以及MMA8451/2/3Q电路图与PCB布局图.

　　The MMA8451Q is a smart low-power, three-axis, capacitive micromachined accelerometer with 14 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. There is access to both low-pass filtered data as well as high-pass filtered data, which minimizes the data analysis required for jolt detection and faster transitions. The device can be configured to generate inertial wakeup interrupt signals from any combination of the configurable embedded functions allowing the MMA8451Q to monitor events and remain in a low power mode during periods of inactivity. The MMA8451Q is available in a 3 mm by 3 mm by 1 mm QFN package.

　　MMA8451Q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 μg/√Hz noise

　　• 14-bit and 8-bit digital output

　　• I2C digital output interface (operates to 2.25 MHz with 4.7 kΩ pullup)

　　• Two programmable interrupt pins for seven interrupt sources

　　• Three embedded channels of motion detection

　　• Freefall or Motion Detection: 1 channel

　　• Pulse Detection: 1 channel

　　• Jolt Detection: 1 channel

　　• Orientation (Portrait/Landscape) detection with programmable hysteresis

　　• Automatic ODR change for Auto-WAKE and return to SLEEP

　　• 32-sample FIFO

　　• High-Pass Filter Data available per sample and through the FIFO

　　• Self-Test

　　• RoHS compliant

　　• Current Consumption: 6 μA – 165 μA

　　MMA8451Q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, tap detection for button replacement)

　　图1.MMA8451Q方框图

　　图2.MMA8451Q应用框图

　　LFSTBEB845X: MMA845X系列传感器加速计工具箱

　　MMA845xQ 传感器工具箱

　　The Freescale MMA845xQ sensor toolbox accelerometer kit provides hardware and software for development and demonstration of the MMA845xQ family of accelerometers.

　　MMA845xQ 传感器工具箱包括:

　　• 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.LFSTBEB845x外形图