Other Parts Discussed in Thread: FDC1004
We received the following questions from our customer.
(1) When water droplets on FPC (Flexible printed circuits), we recognize that the sensor's capacitance value changes greatly,
but as shown in the experiment below, there was almost no change with FDC2214.
Does the FDC2214 take any measures against such water droplets?
The LCR meter measures the impedance to calculate the capacitance, but the FDC2214 calculates the capacitance by changing the resonance frequency.
Why is FDC2214 less susceptible?
・When the FDC2214 mounting board and the capacitance sensor are connected via the FPC, there is a change of about 1 to 2 pF when water droplets fall on the FPC.
・When the LCR meter and sensor are connected via FPC, when water droplets fall on the FPC, it changes by about 10pF to 20pF.
(2) As the resistance value on the FPC increases, the measured capacitance decreases. Please tell me the reason why the measured capacitance value decreases.
it would be helpful if you could explain it with a calculation formula.