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About the "out of phase" function of FDC1004

GU changlin
Intellectual 480 points
Other Parts Discussed in Thread: FDC1004

Dear TI FAE

 

I'm using FDC1004 to make LIQUID LEVEL SENSOR .

I learned from datasheet P.7  that there is a OoP function inside the IC.

Please see the attach file and could you tell me which is the 0 level ?

thanks.

Charlie from TED

 

FDC1004.xlsx

  • 0
    TI__Expert 7400 points

    Hi:

    Please read the application note on Out of Phase liquid level sensing technique.

    Thanks

    -David Wang

    Capacitive Sensing Application

  • 0 in reply to David Wang11
    Intellectual 480 points
    Hi David

    I had read the liquid level sensing technique.
    I still didn't find out which is the 0 level.

    thanks .
    BR
    Charlie
  • 0 in reply to GU changlin
    TI__Expert 7400 points

    Hi:

    The waveforms on the CINx and SHLDy lines do not have anything to do with level calculation. That is just a representation of what the waveform looks like coming out of the pins. This essentially charges and discharges the sensor at 25kHz. Please read the app note carefully, level calculation is based on Equation 2 which can be found on page 3. You need to know the capacitance when the tank is empty and the capacitance at a specific level height for the LEVEL and REF sections. Then the simple way is just a division method between the change in LEVEL and REF measurements. The capacitance raw values outputted from the device, that is what you read out from the FDC1004.

    Thanks

    -David Wang

    Capacitance Sensing Applications