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LDC1101: Ferrit-based sensor with low Quality factor

Lars Kamm
Prodigy 10 points
Part Number: LDC1101

Hi,

We would like to use the LDC1101 in a project where a ferrite-based sensor is operated. The problem is the low quality factor, which is limited by the poor core material (q-factor value of 7 to 8). Unfortunately, this core material cannot be replaced and even changes to the windings have not improved the quality factor. Also the frequency is fixed at 3.7MHz and should not be further reduced.

According to the datasheet, the quality factor should not be less than 10.


Now to my questions:
- Can the LDC1101 be operated with a quality factor of less than 10?
- What are the influences of a too low quality factor?


Regards,

Lars

  • 0
    TI__Genius 11340 points

    Hi Lars,

    The quality factor determines how much noise is present. Having a low Q value means that the device is less immune to noise interference. We recommend having Q>10 to get clean measurements. The equation for Q is as below:

    The true limits for Q are the sensor frequency (determined by L and C) and Rp (specified by idrive). In section 8.1 of the LDC1101 Datasheet, you can see that we recommend Rp to be between 1.25kohm and 90kohm.

    Best,

    Jiashow