Accelerometers

1. AccelerometersAccelerometers
EE 587
By: David Jackson

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

3. 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

4. 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

5. How It Works – SurfaceHow 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

6. 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

7. 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

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