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Power over Ethernet (PoE) basics and beyond

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257 points voxadam | 1 comments | 16 Oct 25 14:09 UTC | HN request time: 0.199s | source
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willis936 ◴[22 Oct 25 02:40 UTC] No.45664343[source]▶
Other stuff engineers should know:

- PoE endpoints should have isolation barriers, factor this into cost and size estimates

- Don't skimp on TVS

- ideal diode full bridge rectifiers are really cool and you should use them (in more power entries than just PoE)

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dynode ◴[22 Oct 25 03:07 UTC] No.45664517[source]▶
Awesome I’m just doing a POE design now.

- Was having a conversation today about isolation and grounding for POE (product has a metal case). Do you have a reference? Or standard?

- TVS ahead of the bridge right?

- Do you have a part recommendation or reference design for ideal diode POE?

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1. zxcvgm ◴[22 Oct 25 11:14 UTC] No.45667385[source]▶
I use the FDMQ8205. It's an old part, a little pricey, but keeps the board footprint low. It also has a sufficiently high UVLO, so it acts like regular diodes during the classification phase and you don't need to factor those in to the Rcls values.