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LDC1000EVM: LDC1000 Inductance Problem

kshinoda
Prodigy 20 points
Part Number: LDC1000EVM
Other Parts Discussed in Thread: LDC1101EVM, LDC1101

I am testing a combination of LDC1000EVM and Proximity Sensor (OMRON E2C-X10A)
But there is a problem.

Inductance measurement value of LCR meter(sanwa LCR700) and LDC1000 does not match.
<< OMRON E2C-X10A >>
LCR meter(100kHz): 69uH
LDC 1000: 1252uH (Frequency:450kHz,  Sensor Capacitor 100pF)

<< Coil printed on board of LDC1000EVM >>
LCR meter(100kHz): 17.4uH
LDC 1000: 19.54uH (Frequency:3.6MHz)

Why is the inductance not calculated correctly in E2C-X10A?
Please tell me if you have any idea.

  • 0
    TI__Genius 13335 points
    Hello,
    I am not familiar with the OMRON E2C-X10A, however I would first confirm the inductance vs frequency curve with the manufacture to see what the true inductance is. It could be that the inductor you've chosen has a very low self-resonant frequency so the difference between 100kHz and 450kHz gives a significantly different reading. I would also double check the capacitor value to ensure that it is indeed 100pF.
    For the PCB coil, the readings look to be about 10% off which could be the case for the LDC1000. If you are looking for a more accurate reading of inductance then I would recommend the LDC1101 which is a very similar device but with significantly improved accuracy. You can also find an evaluation module online: LDC1101EVM
    Hopefully this helps point you in the right direction!
    Regards,
    Luke
  • 0 in reply to Luke LaPointe
    Prodigy 20 points

    Hello, Luke.

    Thank you for helpful information.
    By calculation, I think that Omron's sensor also contains a C-tank condenser. Maybe 1700 pF.
    I connected only the sensor without connecting a capacitor to LDC 1000 EVM.
    Impedance was a good result, but inductance was a result that individual difference was large.
    Therefore, I will use impedance instead of inductance to make measurements.

  • 0 in reply to kshinoda
    TI__Genius 13335 points
    Hello,
    Thanks for the reply and the confirmation!
    Cheers,
    Luke