1. Accelerometers EE 587 By: David Jackson

2. Accelerometers Types of Accelerometers How Surface Micromachined Capacitive Accelerometers Work Tilt Sensing with Accelerometers ADXL202AE

3. Types of Accelerometers Peizo-film – used in AC applications to sense motion, sound, temp. and pressure Surface Micromachined Capacitive – used in DC applications to measure tilt, vibration, and inertial

4. Types of Accelerometers Bulk Micromachined Capacitive – used in DC applications to measure tilt, vibration, and inertial Electromechanical Servo – DC applications to measure tilt and inertial Piezo-electric – AC applications to measure vibration and shock

5. How It Works – Surface Micromachined Capacitive Suspended Beam held in place by tethers Acceleration in either direction caused movement in the beam With movement of beam, capacitance between plates changes The difference is measured and the direction and force are determined

6. Tilt Sensing Accelerometer measures the static gravity field Acceleration of 9.8m/s = 1g Changing the tilt (along the sensitive axis) changes acceleration vector

7. ADXL202AE Operating Temperature – -40 to 85°C Voltage – 3.0 to 5.25V Current – Typical 0.6mA Max 1.0mA Output – Digital – Duty Cycle Modulated or Analog Weight – less than 1 gram

8. References http://www.analog.com