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Hey Lennart, As always, thanks for your hard work on this. Seems like we’re converging on a solution. I’m still reviewing, but wanted to point out a concern I have regarding the ‘reflected voltage’ requirement: “A PSE, operating in 2-pair mode shall not draw a current higher than 1.3 mA on the negative pair of the unpowered pairset.” Taken in isolation, I believe this requirement is missing a critical qualification: applied voltage. Surely we do not want to enforce this requirement e.g. for applied voltage greater than PSE output voltage. My proposed change: “A PSE operating in 2-pair mode shall not sink current greater than 1.3mA on the negative pair of the unpowered pairset for any voltage applied in the range of 0 V to VPSE-OC, where VPSE-OC is the open circuit voltage of the powered
pairset.” Notice a new term VPSE-OC, to address a concern that VPSE specifies a measurement point but does not qualify who is applying this voltage. This solution attempts to clarify that the maximum applied voltage during this test should be no
greater than the PSE output voltage. -David From: Lennart Yseboodt [mailto:lennart.yseboodt@xxxxxxxxxxx]
Hi folks, I've updated the slides to explain some of the associated topics that go with backfeed. Ken - your 2nd proposal is extremely close to very similar text I had prepared earlier - we must be on the right track :) Attached slides + baseline. Yair has asked the group to perform the due dilligence on 3P backfeed. Given how late in the process we have discovered this issue, that seems like sound advice. Let's keep digging and make sure we're not shooting ourselves in the foot. Based on my current understanding, there are serious negative consequences associated with imposing a 2.8V requirement on PDs in 3-pair condition. As such, I would propose to restrict the backfeed spec to 2P only, while we continue to check
for potential issues. Kind regards, Lennart To unsubscribe from the STDS-802-3-4PPOE list, click the following link:
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