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  • TI Thinks Resolved

FDC2114: Clarifying how the sensor works

Prodigy 80 points

Replies: 1

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Part Number: FDC2114

I asked a question a few days ago and got partial clarification. I want to make sure that I understand the mechanism that the LDC2114 is using. As I understand, a current source drives the LC circuit, and it uses the zero-crossings and the known value of L to back out the value of C. (I've drawn out what I believe the mechanism is... though if this is right, the frequency is sqrt(LC) instead of the usual value of omega = 1/sqrt(LC))

  • Evan,

    What you are missing is that the current source is an AC source. It pushes back and forth across the circuit.

    There are two pieces to it:
    - drive the circuit at its resonant frequency (this is done how I described before)
    - measure the resonant frequency by comparing it to a reference frequency

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