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[802.3af] RE: Max classification time for PD spec



Yair, David and Thong,
 
 
TI Engineering agrees to the spec changes proposed by Yair.
 
 
Regards,
Steve
 
-----Original Message-----
From: Yair Darshan [mailto:YairD@xxxxxxxxxxxxxx]
Sent: Monday, August 12, 2002 9:54 AM
To: 'Dave Dwelley'; Thong Huynh (E-mail); Hemmah, Steve
Cc: 'stds-802-3-pwrviamdi@xxxxxxxx'
Subject: Max classification time for PD spec

Guys,
 
We have specified min and max classification time for the PSE spec.
It means that the PSE will sense the current or voltage after 10ms from the time that the Voltage  or current to the PSE port and the whole function will be ended after total of 75ms.
 
The reason for 10ms min was to allow the PD enough time to get stable.
 
Now we have to limit the max stabilization time of the circuits at the PD to keep our 6db margin.
 
So I suggest to define at the PD spec at table 33-13 as follows:
 
Add item 7 to the table. Parameter: "PD classification stability time " , Unit:"ms", value: 5ms max.
Add note for item 7: "Measured from the time that classification voltage or current applied to the PD port until the voltage or current reached to their 1% of their steady state value"
 
Summary:
 
The classification circuits at the PD will be stable within 5ms max.
The PSE will start to take data after 10ms min. and will remove classification voltage/current within 75ms max.
 
Please check (PD chip vendors) if you can meet those numbers or suggest modifying it.
 
Regards
 
Yair
 
 
Darshan Yair
Chief  Engineer
PowerDsine Ltd.  -  Powering Converged Networks
1 Hanagar St., P.O. Box 7220
Neve Ne'eman Industrial Zone
Hod Hasharon 45421, Israel
Tel:  +972-9-775-5100, Cell: +972-54-893019
Fax: +972- 7755150-09
E-mail: <mailto:yaird@xxxxxxxxxxxxxx>.  
<http://www.powerdsine.com>