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Re: Inductive Proximity sensor output stability issue

Yeshwanth Kumar Jayakrishnan
Prodigy 150 points
Other Parts Discussed in Thread: LDC1614EVM, LDC1614

Hello
I am using lDC1614EVM for inductive sensor design.
I am  facing an problem with regards to the sensor output.
The following is my setup  done for my experiment:
External Inductor coil PCB -10mmx10mm is connected to channel 3 of LDC1614EVM. They are connected with a 100mm shielded cable with the shield of the cable being grounded.
The problem I face is that:
The "RAW CODE" read from the sensor (through TI exe) continues to reduce, the value doesn't attain a stable position and I suspect this because I am using a 100mm shielded cable routed through a sheet metal.

I request to to clarify on my below doubts:
1) Is there any way we could control and stabilize the output value of the sensor( while the wire remains to be routed through the sheet metal)??
2) Is it mandatory to design the coil and Sensor(LDC1614) in same PCB?
3) In case I am able to achieve the above case can I take the clock pin from an external PCB connected with a wire of 200mm>?? Will the increasing the clock distance cause problem in frequency?

4) supposing I use LDC1000 for the same setup (External Inductor coil PCB -10mmx10mm is connected to channel 3 of LDC1614EVM. They are connected with a 100mm shielded cable with the shield of the cable being grounded.), will I have a better stable output?? I ask this because LDC1000 works on eddy current principle and LDC1614 works on frequency method.
We await for your reply.

Regards
Yeshwanth kumar

  • 0
    TI__Genius 14270 points
    Hello Yeshwanth,

    The sensor and coil do not need to be located on the same PCB; remote connection through a connector is acceptable. I recommend using un-shielded twisted pair, and not coax to connect the LDC to the sensor.

    Also, consider the sensor frequency; a higher sensor frequency cannot be placed as far away from the LDC; for a 100mm distance, the sensor frequency should be below 4.8 MHz, even when the target is closest to the sensor.

    The LDC1000 is not as accurate as the LDC1614; unless you need to measure a sensor Rp at a frequency below 500 kHz, you should either stay with the LDC1614.

    Regards,

    ChrisO
  • 0 in reply to Chris Oberhauser66
    Prodigy 150 points
    Thanks ChrisO, Will routing the cable through a metal sheet effect the performance ?? (the coil and LDC1614 are connected through the cable which passes over a metal sheet)
    Thanks