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Low power capacitive touch detector

  • US 9,151,789 B2
  • Filed: 09/15/2011
  • Issued: 10/06/2015
  • Est. Priority Date: 09/15/2011
  • Status: Active Grant
First Claim
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1. A method of detecting a capacitive touch input, the method comprising:

  • charging a parasitic capacitor of a capacitive sensor;

    enabling the parasitic capacitor to discharge through a resistor coupled to the parasitic capacitor, wherein the discharge is in a first current direction through the resistor;

    timing the discharge of the parasitic capacitor through the resistor to produce a first discharge time;

    thencharging the parasitic capacitor again;

    enabling the parasitic capacitor to discharge through the resistor in a second current direction opposite to the first current direction;

    timing the discharge of the parasitic capacitor through the resistor to produce a second discharge time; and

    detecting a touch event based on the first discharge time and the second discharge time.

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