ADXL203: Self-test calibration

Document created by analog-archivist Employee on Feb 23, 2016
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We would like to use your ADXL203 like a tilt sensor in safety critical
applications like platforms stability control (with humans on board). We MUST
BE SURE that your ADXL203 works well without double it.

We do not understand well the self test procedure (carry on via the test pin).
We need to know HOW the output change with the test pin use.

Using this pin test it is possibile to understand if the accelerometer drifts
or not works properly? It is possible to know the accelerometer drift and with
what precision?


The self test feature designed in all of our inertial sensors activates the
mechanical structure of the device which in turns generates a signal through
the electronic portion of the chip, thereby allowing the user to verify proper
operation of the entire device.  By applying a logic 1 signal on the ST pin, a
voltage is applied on special self test 'fingers' located around the moving
element of the sensor.  This voltage creates an electrostatic force which
causes the structure to move.  The sensor displacement generates an electrical
signal on the sensing fingers, as if the sensor were moved under normal
acceleration.  The signal is processed through the signal conditioning
circuitry and appears at the output of the device.  The self test feature
therefore exercises every part of the chip.  A proper output signal is
therefore indicative that the entire sensor is functional. 

The self test feature cannot be used to verify drift of the device.  It should
not be used to verify parametric compliance.  It should only be used to verify
functionality.  If changes such as drift over temperature cannot be tolerated
in the application, these need to be addressed through calibration or
temperature compensation routines.