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FDC1004: Incorrect detection value of FDC1004

Jimmy Zhou95
Intellectual 870 points
Part Number: FDC1004

I use FDC1004 for capacitance detection. The channel 1 is connected a 4pF capacitor with channel 2 for 5pF capacitor. However sometimes, the detected capacitance of CH 1 change to 15pF(correct value is 5pF) with CH2 5pF(correct value). What cause this?

  • 0
    TI__Genius 17440 points
    Hi Jimmy,

    Are you using the FDC1004EVM or a different board? The FDC1004 will detect all capacitances on the sensor path, not just the capacitance of the sensor itself. The shield pins can be used to minimize parasitic capacitances along the sensor path, but the sensor will still be sensitive to dielectric changes in its vicinity. If the capacitance saturates (which is what is happening when it measures 15pF), there has likely been a change in the environment surrounding the sensor that has significantly increased the capacitance.

    Regards,