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FDC2214EVM: FDC2214EVM evaluation Board.

Kruthi N K
Prodigy 140 points
Part Number: FDC2214EVM
Other Parts Discussed in Thread: FDC2214

Dear Sir/Madam,

In one of our project we are using FDC2214EVM evaluation Board.

There are 4 channels CH0, CH1, CH2 & CH3.

We are inserting capacitor with known value in CH2 and CH3 to detect proper capacitance value using GUI.

Firstly we are using only CH2, then the value observed in GUI is having +2% tolerance 

For  62pF Capacitor, in GUI we observe 64pF capacitor.

Then if we are using only CH4, then the value observed in GUI is having +4% tolerance 

For  62pF Capacitor, in GUI we observe  66pF capacitor.

So therefore the value is different for different channels.

How to achieve same value in two different channels with similar tolerance or less tolerance?

Please lets us know for any design consideration changes.

Regards,

Kruthi

  • 0
    TI__Genius 14270 points
    Hello Kruthi,

    LDC FDC2214 has very good matching channel-to-channel. The most likely cause of the difference is the tolerance of any fixed capacitors and or the parasitic capacitance on the channel, including the parasitic capacitance of the inductor. You could try checking with a different value cap on all 4 channels and you should see the same offset on the channels.

    Another possible cause is incorrect settings - make sure the sensor drive amplitude (set by IDRIVE) is within the recommended operating range.

    Regards,

    ChrisO
  • 0 in reply to Chris Oberhauser66
    Prodigy 140 points

    Hello Chriso,

    We tried changing the drive current for a channel CH2, the value obtained in GUI is similar.

    But if we change capacitor value for the channel CH2 , we have to set different drive current value.

    Whether we have to set different drive current value in channel CH2 for change in capacitance values??

    Regards,

    Kruthi