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LDC0851: EVM with two external 10uH inductor, LED does not change when metal gets close

Part Number: LDC0851

Hello Team,

We are testing LDC0851 with external 10uH inductor as shown below. C4 is removed.

I am not sure why the inductor seems to become only sensitive to hand touch.

It seems that metal target cannot change the LED light.

May we know why?

Thank  you.



  • Hi Ting,

    You are seeing two effects. First, the reason that the inductors no longer detect the presence of metal is that the shape of the inductors "trap" the magnetic field and the magnetic field does not extend outside of the inductor.

    As for the touching causing a detection, this is most likely due to operating the sensor at the SRF of the inductor - small shifts in parasitic capacitance are sufficient to move the sensor's resonance frequency.



  • Hello Chris,

    Thank you for replying! Understood clear now!