How to implemnt POE with strange RJ45 configuration

Thread Starter

epic511

Joined Mar 16, 2019
3
Hello,

I am interested in adding POE to a design which has a 2337993-2 RJ45 jack from TE connectivity. I plan to use the LM5070 from TI for the controller.

Looking at other implementations of POE the Data pair and the spare power pair are individually sent through rectifiers. However, with this jack that is not possible because the pairs are internally connected in the jack. How should I treat these pairs when implementing POE?
 

Irving

Joined Jan 30, 2016
1,064
They have built in isolation transformers on the signal lines. but P7 (+) and P8 (-) still provide power off the line! (via diode bridge and an isolated DC-DC converter) on 802.3af 10/100Mbps Mode B. Because i7/i8 and i4/i5 are joined you can't implement 1Gbit mode B, but those sockets only rated for 10/100 anyway.

1595356670742.png
 
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