飞思卡尔(Freescale)公司的MMA7455L是小型低功耗±2g/±4g/±8g三轴数字输出加速度计,具有信号调理,低通滤波器,温度补偿,自测,以及可配置到检测0g或脉冲检测快速运动等功能,工作电压2.4V到3.6V,典型应用在手机,PMP,PDA,硬盘驱动(HDD),笔记本电脑,步程计和运动检测等.本文介绍了MMA7455L主要特性, 简化功能方框图, I2C接口到MCU的连接图与电路图以及SPI接口到MCU的连接图与电路图。

　　MMA745xL:±2g/±4g/±8g Three Axis Low-g Digital Output Accelerometer

　　The MMA7455L is a Digital Output (I2C/SPI), low power, low profile 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.

　　MMA7455L主要特性：

　　Digital Output (I2C/SPI)

　　3mm x 5mm x 1mm LGA-14 Package

　　Low Current Consumption

　　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

　　MMA7455L 典型应用：

　　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

　　图1.MMA7455L简化功能方框图

　　图2.MMA7455L I2C接口到MCU的连接图

　　图3.MMA7455L SPI接口到MCU的连接图

　　图4.MMA745xL评估板外形图

　　图5.MMA7455L I2C接口到MCU的连接电路图

　　图6.MMA7455L SPI接口到MCU的连接电路图