LDC1101: The inductor L result offset

Shinya Sawamoto

Part Number: LDC1101

Team,

I have a couple of questions of LDC1101 as follows.

1) The inductor L result sometimes shows offset though the target and the sensor keep the same position. Is there any possible reason to be caused that?

2) Is there any possibility and reason that a resonant frequency to measure the inductor value could be shifted during toggled the sleep mode or power supply?

Thanks in advance.
Shinya Sawamoto

over 6 years ago

0 Clancy Soehren over 6 years ago

TI__Mastermind 23810 points

Are you using RP+L mode or HRL mode?

0 Shinya Sawamoto over 6 years ago in reply to Clancy Soehren

TI__Expert 5285 points

Hi Clancy,
It's RP+L mode.
The offset looks larger as longer the off time interval or discharge time before re-toggled to on.
Is there any potential reason?

0 Shinya Sawamoto over 6 years ago in reply to Shinya Sawamoto

TI__Expert 5285 points

Hello,

Any feedback to this question?
Please let me know, if there is an additional information you need to answer it.

Regards,
Shinya Sawamoto

0 Clancy Soehren over 6 years ago in reply to Shinya Sawamoto

TI__Mastermind 23810 points

Shinya,

You could be observing temperature drift over time. The RP+L mode will be more susceptible to this, although it can be observable with HRL mode as well.

Temperature drift can cause small changes in the reference oscillator, external components (such as the parallel cap, it should be C0G grade to combat this), and of course changes in the sensor and target itself. The LDC1101 is so sensitive, that even slight variations are detected.

0 Shinya Sawamoto over 6 years ago in reply to Clancy Soehren

TI__Expert 5285 points

Thanks Clancy,
I'll try debugging with keeping mind that instruction.

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LDC1101: The inductor L result offset