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Re: [8023-POEP] System Architecture



Title: System Architecture

Yair,

 

I have a few comments:

 

  1. 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.

 

  1. I can’t picture a PD that uses more than 2 PSEs.  I don’t think we need to worry about this “Nx2P” architecture.

 

    1. 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.

 

    1. 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>.  
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