Moisture compensating capacitive sensing circuit
Abstract:
A capacitive sensing circuit includes circuitry to compensate for moisture or liquid spanning sensor units. The capacitive sensing circuit includes input terminals that couple with respective sensor units to receive sensing signals. A sensing block determines capacitance changes in the sensor units using the sensing signals and generates output signals indicative of the sensed capacitance changes. First switches are coupled with respective ones of the input terminals and are closed during a first scanning stage to couple the sensing signals from the input terminals collectively to the sensing block. Second switches are coupled with respective ones of the input terminals and are closed during a second scanning stage, to generate compensation signals to compensate for capacitance interference between the sensor units.
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