PoEp Power Architecture-AC Input
One of the arguments for not using 51V power supply is that back up battery operates up to ~ 43 - 44V.
However most batteries used in telecommunication have one of the terminal grounded (mostly positive)
This would prevent direct use of this batteries in POE and would require to have isolated converter between batteries and PSE regardless of output voltage considerations
Therefore increasing output voltage to ~51V would not add any system cost
But boost converter would be useful even in case of isolated batteries (DC UPS), which really is not very popular power architecture.
www.PowerDsine.com | PowerDsine Presentation | October 2005 | Page 9 |