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FDC1004QEVM: Fixed capacitance measurement

karthikeyan R81
Prodigy 130 points
Part Number: FDC1004QEVM

Hi, 

I am new to FDC1004QEVM Board.

For testing the working functionality of this board, I am connecting the fixed capacitance (47pF) between CIN2 and GND. But it is not giving the correct value in sensing solution tool. Please refer in the attachment.

My aim is to measure the liquid(oil) level before going to that directly just I want to understand the working functionalities.

Thanks

  • 0
    TI__Expert 6625 points
    Hi Karthikeyan,
    Did you test the EVM without a cap to see if there's any parasitic capacitance? If you happen to measure a parasitic capacitance of 16pF (without the cap), then what you're measuring makes sense.

    Best Regards,
    Bala Ravi
  • 0 in reply to Bala Ravi
    Prodigy 130 points

    Hi,

    Yeah, I corrected it. 

    I have another query on this,

    Q1. How to select capdac value? and how to find actual value after subtracting capdac value. Do you have any calculation related to this?

    Q2. I want to remove parasitic capacitance from actual measurement. Like parasitic capacitance is 16.444pF. I want to offset this value. But in the GUI decimal point is not available in the offset. what is the solution for this issue?

    Regards,

    Karthikeyan

  • 0 in reply to karthikeyan R81
    TI__Expert 6625 points
    Hi Karthikeyan,
    We do not have any calculation related to that. Since it's a linear relationship you can do your own compensation using y = mx+b. We do not have an offset option in the GUI but if you go to the data streaming page in the GUI, you can download the log file and make the offset in excel.

    Best Regards,
    Bala Ravi