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LDC1000 / Measured distance

Guru 11170 points
Other Parts Discussed in Thread: LDC1101

Hi,

Please let me know about Fig.3 and Fig.4 in datasheet of LDC1000.
The curve of characteristic short than the 0.5mm distance is not plotted in Fig.
If operate in short than the 0.5mm distance,
  -  Is the device output error?
  -  Is the device able to measure the  inductance in 0 distance?

Regards,
Nagai

  • Hello Nagai-san,
    The curve cuts off at about 0.3mm so that the measurement does not bump the sensor. There is no limitation on how close the target can be to the sensor provided that it meets the Rp requirements specified in the datasheet of >798Ω.
    Also, assuming that you have soldermask on the PCB traces the metal could touch the PCB sensor and still read a value. However over time if the metal rubs off the soldermask and touches the copper traces directly then you run the risk of shorting out the coil or changing the inductance to something unexpected. Therefore we recommend some distance >0mm to account for mechanical tolerances and to ensure that the target doesn't bump the sensor itself.
    Also for proximity measurements, we recommend to use the L mode over the Rp mode to achieve greater accuracy. If you are using the Rp mode to take advantage of the comparator feature you could also consider using the LDC1101 which has very similar functionality but offers the ability to use the comparator feature in L mode.
    Regards,
    Luke LaPointe