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LDC1612: Product selection and sensing range

Param Dandekar
Prodigy 100 points
Part Number: LDC1612

Tool/software:

Hi Team,

Customer wants to design an inductive proximity sensor with the following requirements:

  1. Sensing range: 120 mm
  2. Max PCB width: 50 mm
  3. Sensing resolution: 10 mm (should give around 100mv for 10 mm movement)
  4. Accuracy: ±2 mm
  5. Preferred supply voltage: 12V. Though open to 5v is needed.

They have also asked about "target PCB airgap requirements. ( eg- 2 mm +/- 1 )", but as far as I know there is no such requirement for the device.

I understand that all of our LDC devices have I2C output, but apart from that is this feasible with LDC1612? The datasheet does say "the high resolution channels allow for a much larger sensing range, maintaining good performance beyond two coil diameters", but I have seen some discussions on E2E that only up to 100% of coil distance is recommended? Please advise on this.

Regards,
Param

  • 0
    TI__Mastermind 40295 points

    Param,

    It is unlikely the customer will be able to achieve their requirements with an inductive sensor. 
    You can achieve high resolution with an air gap of 3% to 20% of the coil radius.
    You can sometimes detect the presence of a target at an air gap that is 50%-100% of the coil radius, but with no add'l resolution. You will not be able to estimate any changee in distance.

    Regards,
    John

  • 0 in reply to John Miller - Sensing
    TI__Prodigy 100 points

    Hi John,

    Sorry, I think I had misunderstood the requirements - the customer has said "a linear inductive sensing application" which I believe means the sort of application described in LDC1612/LDC1614 Linear Position Sensing. I am going to try and have a call with them to understand exactly what they want.

    In this case,

    • Are there any guidelines on the PCB width apart from "wider than the target"?
    • Is there a required/recommended airgap? Of course the target mustn't scrape against the coil, but apart from that I assume a minimal airgap is best?
    • The minimum PCB length is then just the sensing distance (120mm) + the space needed for the circuitry if I understand correctly?

    Thanks,
    Param

  • 0 in reply to Param Dandekar
    TI__Mastermind 40295 points

    Param,


    It is quite common for customers to ask for recommendations without fully sharing their requirements, and this always delays getting them the answers they need.

    So it is probably best to wait until we understand their requirements better before we try working through detailed guidance and feedback.

    Regards,
    John