|
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. MMA8451Q是一個智能低功耗，3軸，14位分辨率的，電容式微機械加速計。該加速度計具有很多靈活的，用戶可編程選項，配置有兩個中斷引腳。其嵌入式中斷功能可降低整體功耗，減輕主機處理器處理數據的負擔。其接口可連接低通濾波數據，以及高通濾波數據，大限度地減少了顛簸檢測和快速轉換所需的數據分析。該設備可以配置為慣性喚醒，用以中斷可配置嵌入式功能組合產生的信號，使得MMA8451Q在閑置期間進行監控，并保持在低功耗模式。MMA8451Q為3mm×3mm×1mm QFN封裝。 
圖1 MMA8451Q方框圖
圖2 MMA8451Q應用框圖 MMA8451Q主要特性 •1.95V~3.6V的電源電壓 •1.6V~3.6V的接口電壓 •±2G/±4G/±8全范圍動態選擇 •輸出數據速率（ODR），從1.56Hz~800Hz • 99μg/Hz噪聲 • 14位和8位數字輸出 • I2C數字輸出接口（4.7kΩ上拉，2.25 MHz運作） • 7個中斷源的兩個可編程中斷引腳 •三通道嵌入式運動檢測 •自由落體運動檢測：1通道 •脈沖檢測：1通道 •顛簸檢測：1通道 •方向（縱向/橫向）檢測，可編程遲滯 •自動喚醒，并返回到睡眠的，自動ODR變化 • 32采樣FIFO •每個樣品，通過FIFO，高通篩選數據 •自檢 •符合RoHS標準 •電耗：6μA~165μA MMA8451Q典型應用 • eCompass應用 •靜態定位檢測（人像/風景，上/下，左/右，后退/前位置識別） •筆記本電腦，電子閱讀器和筆記本電腦翻滾和自由落體檢測 •實時定位檢測（虛擬現實和游戲的3D用戶位置反饋） •實時活動分析（計步器步計數，為硬盤的自由落體跌落檢測，航位推算GPS備份） •便攜式產品節電運動檢測（手機自動休眠和自動喚醒，PDA，全球定位系統，游戲） •沖擊和振動監測（機電補償，航運和保修使用率日志記錄） •用戶界面（菜單滾動的方向變化，輕觸按鈕更換檢測）
圖3 LFSTBEB845x電路圖(1)
圖4 LFSTBEB845x電路圖(2) MMA845xQ 傳感器工具箱 飛思卡爾MMA845xQ傳感器工具箱加速計套件，為MMA845xQ加速計系列，提供了開發和示范的硬件和軟件。 MMA845xQ 傳感器工具箱包括: • MMA845xQ評估板 • MMA8451Q加速度計子板 • MMA8452Q加速度計子板 • MMA8453Q加速度計子板 該套件需要LFSTBUSB USB接口板，以連接到個人電腦。如果您已經有了MMA8450Q加速計的RD3924MM450Q傳感器工具箱，該USB板就在套件里。MMA845xQ套件的型號是LFSTBEB845x，USB接口板的型號是LFSTBUSB。 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: 
MMA8451Q.pdf
(441.98 KB)
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 來源：網絡 |
