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FDC2212: Capacitance questions

daniel
Genius 5095 points
Part Number: FDC2212

Hi team,

Our client want to survey FDC2212 for wake-up function and change the electrodes to 4.

Please help to provide more information for the following questions,

  1. How do we set the threshold, which will be depending on the mechanical design and manufacturing process?
  2. How does the absolute capacitance varies from pen to pen? do we need factory calibration?
  3. How does the capacitance varies with temperature, altitude, humidity?

Thanks

  • 0
    TI__Expert 8050 points

    Hi Daniel,

    Is this a proximity detection wake-up?

    The threshold should be chosen based on the system signal and noise level, i.e. the threshold level has to be above the system noise floor, but below the typical signal level for active detection.

    The capacitor and inductor on the PCB has some temperature dependence. In addition, ambient variations can cause change in the permittivity of air, which results in change in capacitance. 

    Regards,

    Yibo