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FDC2212: Peak oscillation amplitude at the programmed IDRIVE setting

HM
Intellectual 460 points
Part Number: FDC2212

Hi,

I want to bring it close to the liquid level while lowering the probe and stop it when it contacts the liquid level. Therefore, accurate capacitance value is unnecessary.  However, sensitivity is required because the solution volume is small.

While checking with the evaluation board, sufficient sensitivity can not be obtained with Vpk (1.2 to 1.8 V) described in the data sheet, and if IDRIVE is increased to increase Vpk to around 3 V as a trial, the sensitivity is considerably increased.

What is the problem when using Vpk at 1.8 V or higher?

Best Regards,

HM

  • 0
    TI__Genius 17440 points
    Hi HM,

    In general, operating above 1.8V will reduce your SNR. This may be acceptable for small amounts, but 3V is significantly higher than the 1.8V maximum. Depending on your VDD, you could be already operating at the absolute maximum voltage on any pin (VDD + 0.3). Note that performance may degrade if you operate at the absolute maximum voltage for an extended period of time. The absolute maximum ratings table is intended as a stress rating only.

    Instead, I would recommend increasing your sensor size, which will also increase sensitivity.

    Best Regards,