18.1.1 Step 1: Prevent Clipping

This requires the implementation of a hardware low-pass filter in order to reduce the scale of the noise combined with acquisition signal. The sensor capacitance is combined with a series resistor on the Y (Sense) line, which may be internal or external to the microcontroller.

Note: Internal series resistor is only available in Mutual Capacitance mode with PTC.

The external series resistor helps reduce the effect during ESD. Use at least one 1 kΩ external series resistor as close to the microcontroller pin on the sense lines as possible for both self-capacitance and mutual capacitance sensors.