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

Yair -

Good catch. This is something we need to spec.

All circuits LTC has in development will be OK with the new specs. I'd
guess nearly any integrated solution will be able to meet the 5ms number
without trouble.


At 03:54 PM 8/12/2002 +0200, Yair Darshan wrote:
 >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"
 >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.
 >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>mailto:yaird@xxxxxxxxxxxxxx>.