Tech Note 440 Detail

Principle of Operation - accelerometer

Affected Products:

PS-2119 PASPORT Acceleration Sensor (3-axis)
PS-2118 PASPORT Acceleration Sensor (2-axis)

Problem/Symptom:
How does the accelerometer work?

PASCO Solution:
The PS-2119 accelerometer incorporates 42 differential capacitor cells for sensing acceleration. Each cell is composed of fixed plates and moving plates attached to a beam that moves in response to acceleration. Movement of the beam changes the differential capacitance, which is measured by the on chip circuitry. The sensor also incorporates 12-unit capacitance cells for electrostatically forcing the beam during a self-test. Self-test is activated by the user with a logic high on the self-test input pin. During a logic high, an electrostatic force acts on the beam equivalent to approximately 20% of full-scale acceleration input, and thus a proportional voltage change appears on the output pin. When activated, the self-test feature exercises both the entire mechanical structure and the electrical circuitry.

Creation Date: 09/17/2003
Last Modified: 10/2/2003
Mod Summary: