Charge transfer period tuning

AN4316

18/26

DocID024847 Rev 2

5

Charge transfer period tuning

The acquisition is based on the measurement of the sensor channel capacitance (or a set of

sensors in the case of linear and rotary sensors). The more charged this sensor

capacitance, the more accurate the measure and the better the noise immunity.

To ensure that the capacitance is correctly charged, it is necessary to monitor the pin

connected to the sensor plate or through a metallic coin put on the sensor.

Figure 9. Metallic coin probe

The signal must show a square wave which indicates a fully loaded capacitance.

Figure 10 shows an example of ideal charge transfers and Figure 11 a non-ideal ones.