Hello,
I have general some questions regarding the design of POE injectors. I already understand that we need to use a PSE controller such as TPS23841.
However, I have other questions regarding the overall circuits and the needs of the PSE injecting the power.
1) Is 24V a valid voltage for POE on any of the standards (af, at or bt)?
OR is 44V-57V the only valid voltage range for POE?
2) Is galvanic isolation needed between the supply voltage on the wire and whatever system is used to produce it?
3) How is power injected without access to the primary isolation transformer at the source side or destination?
It seems to me that if you use another transformer that you would compromise signal integrity.
Instead does one do something like the following with a CM choke?