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Re: [802.3_4PPOE] Analysis of usable PD input power in 4P system



Yair,
I also prepared a presentation for the Geneva meeting addressing Objective 4 .
I'm not able to post it on the reflector since it exceeds maximum file size.

If anyone wants to review my presentation in advance, please send me an email and I will send it.

I used a slightly different approach.
I assumed the following starting points:
- no more than 0.6A on each cable
- 100m max cable resistivity is 12.5Ohm +-3%
- the 4 pairs converge at the PD after a bridge (diode or active).

I prepared some spice models and I simulated them in different situations. Schematics, data and results are reported in the presentation.

I found that worst cases for 4P power delivery are on both 100m and 1m cable lengths, for two different reasons: 
-at 100m there are max losses
-at 1m there is max unbalance, so one of the 2-pairs delivers very low current while the other is @0.6A

For 1m cable corner case I used a "best case" resistivity of 6.6Ohm/100m (data from Cat6 cable AWG 23)

As a result, I found that 48W is in any condition an achievable figure with a standard PSE/PD design.

We can make it better in the task force (e.g. specifying a current unbalance figure), but as of today I think this is a good starting point.

Thank you
Christian



From: Darshan, Yair [mailto:YDarshan@xxxxxxxxxxxxx] 
Sent: Friday, July 12, 2013 2:32 PM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: [802.3_4PPOE] Analysis of usable PD input power in 4P system

Please see updated presentation per Kousi comments.
Please let me know if I can add your name as supported for this presentation.

Yair.
----------

Hi all,

Please see attached my 2nd action Item from Victoria BC meeting.
I'll appreciate your comments and Input.
Please let me know if I can add your name as supported for this presentation.
Thanks

Yair


Darshan Yair
Chair
Power over HDBaseT Subcommittee 
HDBaseT Alliance

Chief R&D Engineer
Analog Mixed Signal Group
Microsemi Corporation

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:ydarshan@xxxxxxxxxxxxx>.