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Original question:

LDC0851: What is the largest size of switch using 'LDC0851'?

RE：Answer Suggested: LDC0851: What is the largest size of switch using 'LDC0851'?

HIROAKI YOSHIDA
Intellectual 290 points
Other Parts Discussed in Thread: LDC0851, LDC1101, LDC0851EVM

I checked the coil design tool according to the information you provided, but which items are required for LDC0851?
◎Racetrack Inductor Design
Sample Rate Calculator
×Indcutance and Frequency from Output Code
◎Skin Depth Calculation
×LDC16X...
×◎LDC1XX...
◎Remote Coil Maximum Distance Claculator
◎LDC0851 Calculator Tool
×LDC1101...
Spring Sensor Calculator Tool
◎: Necessary item, ? ◎: Required, ?: Unknown, X: Not required.

We found that the target size depends on the sensor coil, but the small target 50mm x 50mm is the maximum realistic target size as described in Inductive Sensing: Target size Matters.
Is 50 mm x 50 mm the maximum realistic target size?
The target size that we want is more than 1000mm x 1000mm.
Is it possible to design a sensor that can handle that?
I haven't read all the manuals carefully, but I would like to confirm whether or not the LDC0851 can be installed.
I have not read all the manuals thoroughly, but I would like to confirm whether the LDC0851 can be installed or not, so please answer me as concretely as possible.

  • 0
    TI__Genius 17660 points

    Hello, 

    For the LDC_Tools Spreadsheet, here is some brief information on each of the tabs that will be helpful for you: 

    • Spiral_Inductor_Designer - Used for the detailed coil design. Calculates coil inductance and Q factor based on PCB properties
    • SkinDepth - Can be used to determine how thick the target should be for a good coupling between target and coil 
    • LDC0851_Calc - can help with more device specific calculations. 
      • The Sensor Characteristics with Target interaction section shows how the target distance impacts the sensor parameters

    The "Inductive Sensing: Target Size Matters" post is showing how the performance decreases when the target is smaller than the coil. The target can be larger than the sensor without causing a problem. However, the area of the target that couples with the sensor may not take up the whole space. 

    Lastly, the distance between the target and the sensor is limited by the coil size. Since this is with the LDC0851, the set distance for an event trigger should be within 100% of the coil diameter. 

    Best Regards, 

    Justin Beigel 

  • 0 in reply to Justin Beigel
    Intellectual 290 points

    Thank you for your help.
    Table 4 of the LDC0851EVM shows the list of parameters for the LDC0851.
    What do you mean by
    Please tell me the meaning of Trace Width, Trace Spacing and Trace Thickness.
    What do Trace Width, Trace Spacing and Trace Thickness mean?
    Trcae means target, Trace Width: Detection width, Trace Spacing: Thickness.
    Trcae means target, *Width: detection width, *Spacing: detection height, *Thickness: thickness.
    Trcae means target, *Width: detection width, *Spacing: detection height, Thickness: thickness?

  • 0 in reply to HIROAKI YOSHIDA
    TI__Genius 17660 points

    Hello, 

    Hopefully this image helps clear up the confusion around these parameters: 

    Trace Width is the width of the PCB trace (W in the image). 

    Trace Spacing is the distance between traces (S in the image). 

    Trace Thickness is the copper thickness. For example, if you PCB is manufactured with 1oz-Cu, then that is the thickness of the trace. 

    Best Regards, 

    Justin Beigel