AccelerometersAccelerometers

EE 587

By: David Jackson

AccelerometersAccelerometers

Types of AccelerometersHow Surface Micromachined Capacitive

Accelerometers WorkTilt Sensing with AccelerometersADXL202AE

Types of AccelerometersTypes 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

Types of AccelerometersTypes 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

How It Works – Surface How It Works – Surface Micromachined CapacitiveMicromachined 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

Tilt SensingTilt Sensing

Accelerometer measures the static gravity field

Acceleration of 9.8m/s = 1g

Changing the tilt (along the sensitive axis) changes acceleration vector

ADXL202AEADXL202AE

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

ReferencesReferences

http://www.analog.com