Freescale 公司的MMA8451Q是智能低功耗三軸容性微機械數字加速度計,具有14位分辨率,3x3x1mmQFN封裝,電源電壓1.95V-3.6V,接口電壓1.6V-3.6V,動態可選擇滿刻度為 ±2g/±4g/±8g ,輸出數據速率(ODR)從1.56 Hz 到800 Hz,噪音為99 μg/√Hz ,定流消耗6 μA – 165 μA,主要用在電子羅盤,靜態位置檢測,筆記本電腦,電子書,實時位置檢測,手持產品運動檢測,震動和振動監測,用戶接口等.本文介紹了MMA8451Q主要特性,框圖,應用框圖以及MMA845X系列傳感器加速計工具箱LFSTBEB845X主要特性,電路圖以及MMA8451/2/3Q電路圖與PCB布局圖.

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典型應用:

• 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)


圖1.MMA8451Q方框圖


圖2.MMA8451Q應用框圖

LFSTBEB845X: MMA845X系列傳感器加速計工具箱

MMA845xQ 傳感器工具箱

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

MMA845xQ 傳感器工具箱包括:

• 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.

圖3.LFSTBEB845x外形圖

圖4.LFSTBEB845x電路圖(1)

圖5.LFSTBEB845x電路圖(2)

圖6.MMA8451Q電路圖

圖7.MMA8451Q PCB布局圖

圖8.MMA8452Q電路圖

圖9.MMA8452Q PCB布局圖

圖10.MMA8453Q電路圖

圖11.MMA8453Q PCB布局圖
詳情請見:
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA8451Q.pdf?fpsp=1&WT_TYPE=DataSheets&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation
和
http://cache.freescale.com/files/sensors/doc/support_info/LFSTBEB845x__SCH.pdffpsp=1&WT TYPE=SupportingInformation&WT_VENDOR=FREESCALE&WT_FILE_FORMAT=pdf&WT_ASSET=Documentation