power comsumption in RJ45 jacks with common mode

Feb 11, 2005 3 Replies

I am taking over a design that I don't know too much about. It's a network card that has an RJ45 jack with integrated magnetics. The RJ45 has a CMT pin that is connected to 2.5V through some discretes. What does this pin do? Is it a common mode tap? What does that mean? What I really need to know is, does this pin consume any power?



Thanks, John


I did attempt to figure this out. I spent a week googling comon mode, CMT, transformer, rj45, etc. I just didn't find any basic answer that I understood. I could ask the vendor AE, but sometimes I don't want to let them know how much I still need to learn....

John

I

Could it be for Power Over Ethernet?

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uh ? I know of

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but does your design have an active component inside the connector ? never heard of something like that...

or is it more alike the schematics on

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checkout the discrete part, might just be some ground thing

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