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FDC2214: Internal Reference Frequency

Steven Healey
Prodigy 100 points
Part Number: FDC2214

I've been writing code to run the FDC2214 sensor Evaluation board with an Arduino. I've been trying to convert the binary to capacitance, without great success. Could you please explain the reference frequency, Fref, and how that value can be found?

We're running it configured to use the internal oscillator for now. Is that 24 MHz? I've searched through the datasheet, but haven't been able to find what I'm looking for. Please let me know if you can help.

  • 0
    TI__Expert 4720 points
    Hi Steven,

    The internal oscillator value is listed within the master clock section of the absolute ratings as "fINTCLK". The internal master clock frequency range is 35MHz min, 43.4 MHz typical, and 55 MHz maximum. As a recommendation, for precision applications we recommend using an external oscillator as they are typically more stable. The EVM uses a good oscillator.

    The equation to calculate capacitance can be found at the end of section 9.3.2. I would like to note that for most applications the actually capacitance value is not important and the reported data value is typically enough for processing.

    Best regards,
    Blair