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Re: [8023-POEP] Solved another problem with DS



All

 

I think we should try to keep it simple.

 

One simple way would be the following:

 

If the af PSE tries to power the 20W PD, if its current goes higher than Icut, it will go into overload fault and will turn off for at least 750 msec.

 

One way to make sure the midspan will then power the high power PD would be to change the spec so that for a PoE+ PSE Alternative B, the backoff time becomes 500 msec instead of 2 seconds.

 

So, during the fault off time of af PSE, the midspan will take control of the PD.

 

 

Regards

 

Jean

 

Jean Picard

 

Power Interface Systems Engineer

 

Texas Instruments

50 Phillippe Cote Street

Manchester, NH 03101

 

Phone : 603-222-8683

jean_picard@xxxxxx

 

 

 


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Wednesday, May 31, 2006 10:59 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: Re: [8023-POEP] Solved another problem with DS

 

Yair,

 

I think you missed the point.

 

The solution is NOT to “…mandate separate signatures for each 2P…” because we also want “medium power” on 2P.  The Task Force already agreed to this.

 

So there will be some PDs in the 15W to 30W(?) range that have an input structure like an Af-PD (SS with diode bridges).

 

The obvious upgrade path for a user would be to add a medium-power At-midspan in-line with his existing Af-endspan.  These two PSEs can’t share the load since the PD is SS.  So the At-midspan has to supplant (take the place of) the Af-endspan.

 

I showed a method to assure the midspan will power the MP PD every time.  I think this will be essential to the 802.3at standard.

 

Steve

 


From: Yair Darshan [mailto:YairD@xxxxxxxxxxxxxx]
Sent: Wednesday, May 31, 2006 4:11 AM
To: Steve Robbins; STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: RE: [8023-POEP] Solved another problem with DS

 

Steve and all,

 

The problem shown in this presentation can be easily solved by mandating detection and classification signature for every 2P in the PD.

Specifically separate signatures for each 2P and not a common one as measured at the RJ45.

See attached presentation in page 13 for the proposed scope of work.

This is the idea of how standard can be simplified.

Doing the above is not requiring any special specifications from the PSE.

The Endspan PSE will detect and classify pair A.

The Midspan PSE will detect and classify pair B.

Both channels will turned on within the current 802.3af timings or similar to it.

Since each channel A and B are not tied together at the diode bridge output, the PD can be operated easily by using the PD circuitry which is TBD (implementation independent).

 

Yair

 

 

 


From: owner-stds-802-3-poep@xxxxxxxx [mailto:owner-stds-802-3-poep@xxxxxxxx] On Behalf Of Steve Robbins
Sent: Wednesday, May 31, 2006 12:14 AM
To: STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Subject: [8023-POEP] Solved another problem with DS

 

Guys,

 

I think I’ve solved another problem that’s inherent with DS.  See the attached pdf.  (Only about 10 more tough problems to go!) 

 

I’d sure appreciate some comments.

 

Steve