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LDC1614: Need help to understand application of LDC to sense AC solenoid shaft.

Nitin Patil
Prodigy 50 points
Part Number: LDC1614

Hello, I want to design coil for LDC1614 to detect AC solenoid shaft movement. There is no option to place sensor in front of tip of the shaft. Hence, the other design idea I can think of is, The solenoid shaft will be pierced thru the centre of the PCB surrounded by turns of the traces of sensor coil on the PCB.

 

Queries are,

  1. When solenoid shaft is activated, there will be a magnetic field in surrounding of the magnetized shaft in addition to the field generated by LDC1614 sensor coil. Will this saturate or damage the LDC1614???
  2. What is the best LDC part suitable for this application & why??
  3. is there any risk in this design idea??
  • 0
    TI__Genius 10080 points

    Hello Nitin,

    For maximum sensitivity the conductive target needs to be perpendicular to the flow of current. In the case you are describing, the solenoid would be parallel to the sensor coil's magnetic field. Additionally, the AC magnetic field produced by the solenoid can cause issues and potentially cancel out the eddy currents from the sensor coil.

    Please see the below figure (taken from TI Precision Labs - Inductive Sensing: Overview of Inductive Sensing Technology) for reference:

    Due to this, I would not recommend an inductive sensing solution for your application.

    Best regards,

    Nicole

  • 0 in reply to Nicole Khoury
    Prodigy 50 points

    Hello Nicole, Thanks for the reply. That means whenever Solenoid shaft gets magentized, there will be change in LDC count. That is what I want. But my question is, will the LDC1614 gets damaged, if solenoid shaft generates too much of magnetic field .

  • 0 in reply to Nitin Patil
    TI__Genius 10080 points

    Hello Nitin,

    It is not recommended for the target to be moving parallel to the sensor fields. For optimum sensitivity purposes, the target should be perpendicular to the sensor current.

    Additionally, it is hard to say what the effect of the solenoid's magnetic field on the sensor will be. It is possible that the magnetic fields may cancel out and result in little to no change in LDC count. I do not think damage to the LDC1614 would occur, however inductive sensing is not an ideal solution for your application.

    Best regards,

    Nicole