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LDC5072Q1EVM: Need Guidance on Designing Linear Sensor with LDC5072-Q1 Sensor Design Tool

c c
Prodigy 10 points
Part Number: LDC5072Q1EVM
Other Parts Discussed in Thread: LDC5072-Q1, LDC1314, LDC1612, LDC1614

I am trying to design a linear sensor where the coil is smaller than the target, and the coil moves along a long strip-shaped target to achieve an absolute position measurement. Here are my current design parameters:

  • Throw Length (mm): 120

  • Min. Target Thickness (µm): 35

  • Outer Width (mm): 34

  • Width Margin (mm): [Not specified; need advice]

  • Ratio Electrical to Mechanical: [Unsure how to adjust]

When I input these parameters, the generated sensor and target appear to be the same size. However, I intend to design a smaller coil that slides over a longer rectangular target to detect absolute position. Could you please advise on:

  1. How to properly configure the tool for a linear sensor with a small coil and a larger elongated target?

  2. What values or settings should I adjust (e.g., Width Margin, Ratio Electrical to Mechanical) to achieve this design?

  3. Are there any best practices or limitations for designing such a configuration with the LDC5072-Q1?

Thank you for your support! I look forward to your guidance.

  • 0
    TI__Mastermind 43450 points

    Currently, the linear sensor types are not supported in the tool. Could you please provide the customer, use case, and volume for this coil?

  • 0 回复 Vivian Gao
    Prodigy 10 points

    Thank you for your clarification. I understand that the sensor design tool currently does not support the “Type 2” linear sensor configuration, even though “Type 1” linear sensors remain selectable.

    My application is to develop a displacement measurement system similar to a digital caliper, used for measuring object dimensions. The concept is to mount a small sensor coil on a moving part that slides above an elongated rectangular metal target (approximately 240 mm in length, 34 mm in width, and ≥35 µm in thickness). By detecting the inductive change between the coil and the target, I intend to achieve absolute position measurement over the full travel range.

    In light of this, I would appreciate your guidance on the following:

    1.If I proceed with the LDC5072-Q1, is there a recommended workaround or manual design approach to realize this “small coil + larger elongated target” configuration for absolute linear position sensing? What key parameters or adjustments (e.g., coil geometry, target layout, electrical vs. mechanical ratio) should I consider outside the tool?

    2.If this configuration is challenging with the current tool and device, could TI recommend alternative sensors better suited for absolute linear displacement measurement over a ~120 mm range? For instance, are other LDC family devices (such as the LDC1314, LDC1612, or others) or different sensing technologies more appropriate for this type of application? I am looking for a solution that enables straightforward design and reliable absolute position detection.

    Thank you for your assistance, and I look forward to your expert advice.

  • 0 回复 c c
    TI__Mastermind 43450 points

    The LDC5072-Q1 with a linear senso should work in this application. Could you clarify why you want the sensor would be larger than the target in this case? Typically in linear application, the metal target is wider than the coil and moves across the length of the sensor.

    We do have other options for linear sensing in our portfolio. Please refer to this document linked here. Section 3 goes over using the  LDC1614 with a stretched coil. We also offer examples coils including stretched coil linked here.

  • 0 回复 Vivian Gao
    Prodigy 10 points

    Thank you for your prompt and insightful feedback. You are absolutely correct — upon reviewing typical linear sensing applications, I realize my initial design approach may have been mistaken.To better align with the standard practice where the target is wider than the coil and moves along the length of the sensor, I have redesigned the sensor layout. Below is an exported Gerber view of the coil design generated using the sensor design tool:sensor：
    target：


    If it would be helpful for your review, I can also provide the complete set of Gerber files for:

    EVM board

    Sensor coil

    Metal target

  • 0 回复 c c
    TI__Mastermind 43450 points

    This looks good. However please note that the tool does draw an additional half-period on the sense coil that is not needed and will cause issues. Please refer to the image below as to where the sense coil should have stopped,

    If you can account for this issue with the tool, I do not see any issues with the coil.

    If you want me to review the design once you have made these adjustments, if you were to send me the files I would happy to.

  • 0 回复 Vivian Gao
    Prodigy 10 points

    SENSOR.rarEVM.rarTARGET.rarI'm sorry, but the image or file you may have attached does not appear to be viewable on my end.