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Original question:

LMP91300: LMP91300 for the measurements question

LMP91300: The different values from the devices

Daniel Dzivy
Prodigy 30 points
Part Number: LMP91300
Other Parts Discussed in Thread: LDC1101, LDC1612

Hi,

My name is Daniel.

I made design of the PNP sensor with the LMP91300.

I measured two PCB with the two different LMP devices (D4 and D5).

The one measurement is value average from 22 values of the proximity register.

I changed on those PCBs the capacitor CF (CF_4 <-> CF_5), CBY (CBY_4 <-> CBY5), thermistors, coils (the coils inductance is approximately 165uH).

The device D4 has different values than the device D5.

My question: Why is the big different between D4 and D5? Where am I making a mistake?

I send you the schematic, PCB design, BOM, register of values and xls file with the measurement values.

Thank you for your answer.

Daniel

3404.IPS_PNP_V02.pdf

3404.IPS_PNP_V02.pdf

 

3527.The Measurement results.xlsx

  • 0
    TI__Mastermind 23810 points
    Daniel,

    Why don't you try one of the newer LDC devices, such as the LDC1101 or the LDC1612? The LMP91300 uses an Rp measurement, which can have a lot of variability. The LDC1101 also supports an Rp mode if absolutely necessary (at a tighter tolerance than the LMP91300); however, both the LDC1101 and the LDC1612 support an inductance measurement, which can be used effectively for proximity measurements.

    With the LMP91300 you might need to do a calibration routine to adjust for each unit.
  • 0 in reply to Clancy Soehren
    Prodigy 30 points
    Dear Clancy, I need operating voltage 6- 36V. What options have I?
  • 0 in reply to Daniel Dzivy
    TI__Intellectual 1020 points
    Hi Daniel,

    Unfortunately we are not able to support LMP91300 any longer. If you wish to continue to use this device, you will have to debug this issue on your own. It is possible that some of the register settings are not the same when you programmed the device. You can try fresh new parts to check again.

    LDC1101 and LDC1612 are the best devices we can offer as an alternative. You might have to find a way to support step down and regulate the the 6 to 36V supply.

    Regards

    Vaibhav Garg