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Fazy , 07-28-2024, 11:01 AM

I would like to design a specialized esp32 with ethernet and PoE. I'm trying to use a WT32-ETH01 schematic as a baseline, but there is a component called FB1 which I'm not sure, what it is...

I think, this is a 120uH inductor which capable of 1A, and it's on the 3v3 power line, and possibly do some filtering.

Any ideas?

Mini , 07-28-2024, 11:44 AM

FB = ferrite bead. It is simply meant for high frequency filtering. Ferrite bead is kind of inductor, but a special one(very lossy). It should be 120 ohms at 100 MHz. And 1A means max current before it starts to saturate. In this schematic it is meant to add some filtering for AVDD(analog VDD) because AVDD is very sensitive for noise. For example ADC is powered from this.

Mini , 07-28-2024, 11:44 AM

https://www.analog.com/en/resources/analog-dialogue/articles/ferrite-beads-demystified.html#:~:text=A%20ferrite%20bead%20is%20a,in%20the%20form%20of%20heat.

Mini , 07-28-2024, 11:44 AM

https://www.youtube.com/watch?v=HaLMjVkKYMw

Mini , 07-28-2024, 11:45 AM

https://electronics.stackexchange.com/questions/609065/inductor-vs-ferrite-bead

Fazy , 07-28-2024, 12:01 PM

Thanks, I found what I need: https://www.lcsc.com/product-detail/Ferrite-Beads_FH-Guangdong-Fenghua-Advanced-Tech-CBG321609U121T_C39279.html