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Gigabit PoE - component solutions?

Started by Clifford Heath April 20, 2020
I need a inexpensive (i.e. not packaged) solution to delivering clean 
Power over Ethernet at gigabit rates. Yes, I know that balun imbalance 
will limit how clean it can be - but I'd still rather not bring 
unnecessary noise into the remote (box (a radio).

I don't want to buy a commercial packaged solution for injecting power, 
because most don't care at all about noise (I've measured *volts* at 
hundreds of KHz), and they're expensive.

So I'd like to find a passive gigabit Ethernet isolator - a pair of RJ45 
sockets with magnetics, so I can inject my own power from a cleaner 
supply. I've come up with nothing in my searches. Can anyone help?

At the powered end, a normal Gbit Ethernet socket (with magnetics) is 
acceptable - but they're still over $10 or so at stockists. Clearly 
those who manufacture routers don't pay those silly prices, so there 
must be a cheaper source. Any thoughts?

I could use external magnetics following a simple socket, but I would 
still have to route the Gbit traces, so an integrated socket is preferred.

Finally, 4PPoE is allowed to deliver 57V, with the expectation that 
after 100m drop across the 4 pairs, it will be 48V. Those voltages are 
inconveniently high for most switch-mode voltage droppers. What you use 
to drop this to, say, 12V at 3 or 4A?

Clifford Heath.
On Monday, April 20, 2020 at 5:41:42 PM UTC-7, Clifford Heath wrote:
> I need a inexpensive (i.e. not packaged) solution to delivering clean > Power over Ethernet at gigabit rates.
> Finally, 4PPoE is allowed to deliver 57V, with the expectation that > after 100m drop across the 4 pairs, it will be 48V. Those voltages are > inconveniently high for most switch-mode voltage droppers. What you use > to drop this to, say, 12V at 3 or 4A?
There's lots of DC converters in the telecom world to fit those specs; Ericsson's line was sold to Flex, and this one looks like a fit <https://flexpowermodules.com/documents/fpm-techspec-pku5500e>
On 21/4/20 12:00 pm, whit3rd wrote:
> On Monday, April 20, 2020 at 5:41:42 PM UTC-7, Clifford Heath wrote: >> I need a inexpensive (i.e. not packaged) solution to delivering clean >> Power over Ethernet at gigabit rates. > >> Finally, 4PPoE is allowed to deliver 57V, with the expectation that >> after 100m drop across the 4 pairs, it will be 48V. Those voltages are >> inconveniently high for most switch-mode voltage droppers. What you use >> to drop this to, say, 12V at 3 or 4A? > > There's lots of DC converters in the telecom world to fit those specs; > Ericsson's line was sold to Flex, and this one looks like a fit > > <https://flexpowermodules.com/documents/fpm-techspec-pku5500e> >
Yes, the power is the easy bit - though your suggestion is not in the right budget. Can anyone tell me about a paired Ethernet RJ45 socket with suitable magnetics?