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FDC2212: Relationship between ambient temperature and output accuracy

Noriaki Fukazawa
Expert 1620 points
Part Number: FDC2212
Other Parts Discussed in Thread: LDC2114

Dear Expert,

My customers are evaluating FDC2212.

However, FDC 2212 can not keep the output accuracy required by my customers.

This picture is the actual output characteristic.


The output fluctuates due to the change of the ambient temperature.


Is this normal device-specific condition?

<There are several factors that cause the output to be disturbed>

①Register setting

⇒I reviewed the setting of the register and it seems that it improved a bit.

　I will attach a register setting table. Can you check if it is set with wrong register value?

2262.FDC2212 Resistors.xlsx

②Circuit design ＆ Design of sensor partial electrode

⇒If you have direct communication, please contact me.

 

③Temperature characteristic of capacitor

⇒I watched a write like this with another post.

http://e2e.ti.com/support/sensor/capacitive-sensing/f/987/t/578729?tisearch=e2e-sitesearch&keymatch=FDC2212

 


There is no such case, I am in trouble.

I'd like to have a chance to solve problems.

A little advice is OK so please give me a reply.

 

Best,Regars.

Nor

  • 0
    Expert 1620 points
    Dear Expert

    Please advise only whether the device itself has temperature characteristics or
    whether it can be corrected by register setting.

    Best Regars.
    Nori
  • 0 in reply to Noriaki Fukazawa
    TI__Expert 8050 points
    Hello Nori-san,

    Capacitive sensing is sensitive to ambient changes. This can be compensated for with a baseline tracking algorithm.

    Regards,
    Yibo
  • 0 in reply to Yibo Yu
    Expert 1620 points
    Hello Yibo-san,

    Thank you for your reply!
    I understood that the ambient temperature affects accuracy.

    Is it possible to correct distortion of accuracy with register setting?
    In that case, I'd like you to confirm that my registers are correct.

    Support difficulty is high, Customer is in trouble.

    Best Regars,
    Nori
  • 0 in reply to Noriaki Fukazawa
    TI__Expert 8050 points

    Hi Nori-san,

    The FDC2212 does not have built-in compensation for ambient fluctuations.

    However, they may consider LDC2114, which is the third generation part in our resonant sensing portfolio and it has a built-in baseline tracking feature. The LC resonance-based LDC and FDC products are very similar and can be used for both inductive and capacitive applications.

    Regards,

    Yibo

  • 0 in reply to Yibo Yu
    Expert 1620 points
    Hello Yibo-san,

    Thank you for reply.
    I understood that FDC 2212 has no calibration function.
    Does FDC 2214 have a calibration function?
    Also, what I care most about is the FDC 2212 and FDC 2214 have temperature characteristics in the device itself?

    Best,Regars.
    Fukazawa
  • 0 in reply to Noriaki Fukazawa
    TI__Intellectual 2725 points
    HI Fukazawa-san,

    What application is the customer trying to use the FDC device for? Have they considered dedicating one of the channels as a reference channel?

    None of our devices actually measure temperature and compensate for it but like Yibo-san mentioned we can utilized a baseline tracking algorithm to offset slow ambient environment changes. But implementing a baseline tracking algorithm will significantly reduce the ability to do absolute measurements. So more details about the customer's application are necessary before we can propose a solution. Please include a description of the current evaluation setup as well.

    Regards,

    Varn.