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Qi WPC receiver calibration

Sammy Peiren62
Intellectual 310 points

Anyone working with Qi is probably familiar with this figure:

It is the required setup for measuring the self-inductance Ls'. The primary shielding is a 50mm x 50mm x 1mm piece of PC44 ferrite by TDK.

The problem is that PC44 is no longer being manufactured by TDK. I know there is the newer PC47 material with similar specs, but I have no idea where to get this as a 1mm sheet.

Do you know of any alternatives for measuring Ls'?

  • 0
    TI__Genius 14890 points

    Sammy,

    Thank you for the question.

    The WPC spec now references the following materials:

    Material 44 – Fair-Rite Products Corporation

    Material 28 – Steward (Foshan) Magnetics Co., Ltd. (a unit of Laird Technologies)

    CMG22G – Ceramic Magnetic, Inc.

    Additionally, if the solution in development will be with a known transmitter, then using the transmitter itself as the test setup for Ls' is an option.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Intellectual 310 points

    Hello Dick,

    Thanks for the information. Do these all have the same dimensions and thickness as the previous sheet (50mm x 50mm, thickness 1mm)?


    Measuring Ls' with a known transmitter would be the easiest solution, but unfortunately the transmitter is not designed by our company. The customer uses off the shelve transmitters which do not all have the exact same characteristics.

  • 0 in reply to Sammy Peiren62
    TI__Genius 14890 points
    Sammy,

    For specific product information, you will have to contact the suppliers directly.

    Regards,

    Dick