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Original question:

LDC2114EVM: About the calculation method of the value of OUT of LDC2114

LDC2114: About Interlayer PCB thicknes (Spreadsheet “Spiral Inductor Designer” in LDC tools)

user5203911
Intellectual 560 points
Part Number: LDC2114
Other Parts Discussed in Thread: LDCCOILEVM, LDC1612EVM,

Hello

 I have the following questions. I was always wondering.

The coil design uses Spiral Inductor Designer, but there are things you want to check here.

For example, if the thickness of the two-layer coil and PCB is 1.5 mm, how should the distance between the coils in Spiral Inductor Designer be set? *

Should I set the “PCB thickness between 1st layer and 2nd layer” to 1.5 mm?

Looking at the Layer Stackup diagram, it seems that “PCB thickness between 1st layer and 8nd layer” is set for a 2-layer coil. But there is no place to set it. What should I do now?

What should I do for the 4-layer coil? *

Is there a description about the LDC1612EVM or LDCCOILEVM 4-layer PCB structure (thickness between layers) somewhere? If you don't know these, you won't be able to make the correct settings for Spiral Inductor designer PCB Thickness

 

Best regards

  • 0
    TI__Genius 17440 points

    Hello,

    When you have the Layers cell set to 2, you will notice that all of the layer thickness cells are grayed out except for "PCB thickness between 1st layer and 2nd layer." None of the grayed out cells will affect the final inductance calculation, so you should set "PCB thickness between 1st layer and 2nd layer" to 1.5mm. 

    Four a four layer coil, you will see additional layer thickness cells colored yellow instead of gray. You should use these to specify the thicknesses between each layer. 

    I don't believe we have these settings available; however you should not need them. The layer spacing will only affect the mutual inductance of the coil. As the inductance itself does not determine sensing range nor resolution, the layer thicknesses are not critical and are flexible for your design. Just make sure that the "Rp with Target Interaction" cell does not violate the minimum Rp for the LDC device you are using (specified in the Electrical Characteristics table in the datasheet). This ensures that the LDC device will be able to effectively drive your coil.

    Best Regards,

  • 0 in reply to Kristin Jones93
    Intellectual 560 points

    Dear Ms. Jones


    Thank you for your quick response.

    I understood your answer.

    By selecting the coil layer structure, the cells that can be filled in become yellow. However, the relationship between Layer Stackup diagrams and layer settings was a little difficult to understand. Looking at this figure, I misunderstood whether Layer 1st and Layer 8th were chosen for the two-layer coil.

    In the case of LDC2114, the value of “Rp with Target Interaction” cell must be 350Ω ≦ Rp ≦ 10kΩ. (Not just minimum Rp).

    Best regards