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How to tune FOD parameters on the STWBC IC.


I'm using the STWBC as the IC to control the transmitter of a wireless battery charger. So far the battery is charging fine but I am unable to get foreign object detection working. I am adjusting the FOD parameters using the STWBC GUI application. Is there a documented procedure on how to optimize the FOD values?

Either FOD errors occur randomly when there is no foreign object or no FOD error is given when a foreign object is there, depending on the parameter values. The STWBC GUI does show the RX report power drops significantly when I place foreign objects in the way. This leads me to believe it is only the FOD parameters that are the problem.

Associate III

Hi JReid.1, I am nobody but interested in wireless charging (not ST employee).

Have you tried FOD tuning using STWBC86?

If you get connected with ST vendor, they will give you the detailed document tuning FOD parameter.

I've tried it, and as far as I experienced, it worked well so far (method is to measure all the received current level regards to every load volume, step by step)


By the way, if you are interested using wireless charging and wired charging both, using power mux and outputs single one, please reply me. I will be very appreciate it.

It seems the wireless charging's output fluctuates so hard so that the power multiplexer cannot handle the drop, and resets in very short term frequently. Of course no output come out.

Below I attatch the simple diagram, any thoughts or ideas please keep me in the loop.

Thank You.


ST Employee

The FOD tuning is described in UM3161 (for STWBC86 - TX) and
UM3154 (for STWLC38 - RX)

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Associate III

It was not the fluctuation nor the STWBC's problem

It was setting high voltage regarding the Mux's input.

When setting Vout 5V → 4.5V , problem disappeared.