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[802.3_4PPOE] Backfeed ad hoc - 3P detection



Hi all,

 

I believe we are on the right track with the updates represented in the ‘yseboodt_01_0518_backfeed_baseline’.

The only concern I still have is with a “3-Pair PSE” trying to detect a single-signature PD (just for a single port system).

I have the impression the (schottky) diode reverse leakage has not always been taken into account properly:

either just neglected or represented as being a resistor (without additional current source in parallel).

See my presentation in attachment.

My concern is that a PD with real (schottky) diode bridges might become non-compliant to the 3bt standard

and that a “3-Pair PSE” would be allowed not being able to detect a PDs with real (schottky) diode bridges anymore,

due to hard to meet leakage current requirements.

As such I do not have any problem with that, but do we really want to go that far?

 

Next to my presentation, I also attached a spice schematic file for those that would like make simulations.

FYI, the name “3-Pair PSE” is short for “a 4-pair capable PSE providing power in 2-pair mode, whereby two pairs are connected to the positive VPSE, and one pair is connected to the negative VPSE“.

 

 

Best Regards,

 

Joris Lemahieu

Application Engineer

ON Semiconductor

 

+32 55 33 29 49

 

 


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Attachment: Backfeed ad hoc - 3P detection.pdf
Description: Backfeed ad hoc - 3P detection.pdf

Attachment: 3P_detection.asc
Description: 3P_detection.asc