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I'm looking at pcb-mount Ethernet ports like these:

enter image description here

I'm seeing a few different configurations of the magnetics within the ports. On a single Wurth data sheet, there are 4: enter image description here

Schematic 2 is the part we currently use, but is going obsolete. I found potential replacements which look more like Schematic 1.

What is the difference? Are there benefits to the different designs?

Dave
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  • Schematic 4 is gigabit magjack. Others are for fast ethernet (100mbps), with different LPF design...(and performance I suppose). – Flanker Apr 17 '17 at 16:40
  • I would like to know it, too. – Marko Buršič Apr 17 '17 at 18:46
  • Schematic 2 is non-symmetric, thus can not be used for MDI/MDIX implementations. When I was developing network card, there was recommended part to use, but I selected another similar part (from WE by the way) with the same internal circuit, got it approved by chip manufacturer and it works well. – Anonymous Apr 17 '17 at 20:59

1 Answers1

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Schematic 1 offers direct connection to the center tap of the exterior port windings, and is suitable for PoE connection (which may either draw power, or supply power, over twisted pair). Schematics 2 and 4 do not have low-resistance connection suitable for PoE. Schematic #3 does technically have the ability to connect to PoE, but only through an inductor (which may saturate).

Modern designs would usually allow bidirectional use of the four lanes, and #2 does not. It is not surprising that it may become obsolete, in favor of #4.

Whit3rd
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