Yair,
I have a few comments:
- I
think we can all agree that the issue of current sharing is dead. We’ve
already agreed (or at least I think we have) that a 4P system will consist
of 2 independent 2P systems. The two power sources can have voltages
that differ by several volts, and may be on completely different grounds,
again with several volts difference. So no form of linear current
sharing (before the input to the converter inside the PD) will be
practical because of heat dissipation. Therefore, any PD that draws
power from more that one PSE must have isolation between the inputs.
When you have isolation, current sharing is inherent, although not perfect;
the converter with the lowest input voltage will draw more current, but
the current ratio shouldn’t be too severe.
- I
can’t picture a PD that uses more than 2 PSEs. I don’t
think we need to worry about this “Nx2P” architecture.
- I
can easily picture a PD that has two converters inside, to draw power
from two PSE sources. Load sharing with two converters isn’t
bad. But load sharing with N converters becomes messy. I don’t
think anyone would want to bother with it.
- If
someone’s PD really needs that much power, I don’t see how
PoE could be an economical solution. Why not just use AC power?
Why run N cables, using up N ports on your Ethernet switch or midspan?
If the PD really needs so much network bandwidth that it needs N ports
just to achieve the data throughput, then okay. But using N ports
just to get more power? I don’t believe it. Unless
someone can site a practical example I think this topic is a waste of
time, and we should just focus on 2x2P.
Steve
From:
owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Yair
Darshan
Sent: Tuesday, June 13, 2006 4:15
PM
To:
STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: [8023-POEP] System
Architecture
Hi
all,
Please
find my action item for tomorrow's meeting.
It
is revised presentation from May meeting that focus on the concept 4P=2x2P and
the more general case of N Pairs = Nx2P..
Please
feel free to comment.
Thanks
<<Flexible PD implementation driven
Architecture 002.pdf>>
Yair
Darshan Yair
Chief Engineer
PowerDsine Ltd. - The Power over Ethernet
Pioneers
1
Hanagar St., P.O. Box 7220
Neve Ne'eman Industrial Zone
Hod Hasharon 45421, Israel
Tel: +972-9-775-5100, Cell: +972-54-4893019
Fax: +972-9-775-5111
E-mail: <mailto:yaird@xxxxxxxxxxxxxx>.
<http://www.powerdsine.com>