Hi All,
I like the most the last version below:
“"The PD shall turn on at a voltage
greater than Voff and less than or equal to Von or VPort_PD(min) whichever is more".”
Thanks,
Miklos
From: Yseboodt, Lennart [mailto:lennart.yseboodt@xxxxxxxxxxx]
Sent: 2015. március 17. 13:52
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] PD Load turn on
Hi all,
While trying to review this text I noticed there is a difference in behaviour for Type 1 & 4 and Type 2 & 3 PDs.
Specifically it is not clear to me what a Type 2/3 PD should do with PI voltages between Von and Vport_PD(min). The only "shall" that applies says "turn off".
We can fix this by replacing (in 33.3.7.1):
"The PD shall turn on at a voltage less than or equal to Von."
by
"The PD shall turn on at a voltage less than or equal to Von or VPort_PD(min) whichever is more."
or, combined with Kousi's suggested fix it becomes
"The PD shall turn on at a voltage greater than Voff and less than or equal to Von
or VPort_PD(min) whichever is more".
Alternatively we can also change Von = 42.5V.
Attachment shows my interpretation of all shall statements in 33.3.7.1.
Kind regards,
Lennart
From: Koussalya Balasubramanian (kobalasu)
[kobalasu@xxxxxxxxx]
Sent: Tuesday, March 17, 2015 7:10
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_4PPOE] PD Load turn on
Team
I collected the feedback given to me on "PD load turn on maintenance request" and modified the suggested solution little bit. Please see below.
Problem Statement:
Reference - http://www.ieee802.org/3/bt/public/jan15/balasubramanian_02_0115.pdf -
PDs in the field turn on their Load during Inrush. This leads to PD cap not charging up fully (even if C<180uf and PSE is following inrush rules from 33.2.7.5). This may lead to operational problems after inrush. There is a Voff requirement in PD table
33-18 to ensure power supply remains turned off for V<30V, but customers seem to read this as applicable only "after power on" not during "power on" - hence they turn on their DC-DC during inrush causing problems.
Suggested Solution
Add the following to section 33.3.7.3
"PDs shall not draw more than the maximum current allowed by a PSE during inrush as outlined in section 33.2.7.5"
Change 2nd paragraph of section 33.3.7.1 as follows (change shown with underline)
"The PD shall turn on at a voltage greater than Voff and less than or equal to Von"
Thanks
Kousi
From: Koussalya
Balasubramanian (kobalasu) [mailto:kobalasu@xxxxxxxxx]
Sent: Thursday, February 26, 2015 11:09 AM
To: STDS-802-3-4PPOE@xxxxxxxxxxxxxxxxx
Subject: [802.3_4PPOE] PD Load turn on
Team
In Jan interim meeting, Jean and I presented about clarifying PD load turn on behavior that will help
in making sure non-compliant behaviors are avoided. The team directed us to submit this as a maintenance request. Here is what we are planning on submitting – given the maintenance request will come back to 4PPoE group, we would appreciate any comment from
4PPoE group before we submit it.
Problem Statement:
- PDs in the field turn on their Load during Inrush. This leads to PD cap not charging up fully (even
if C<180uf and PSE is following inrush rules from 33.2.7.5). This may lead to operational problems after inrush. There is a Voff requirement in PD table 33-18 to ensure power supply remains turned off for V<30V, but customers seem to read this as applicable
only "after power on" not during "power on" - hence they turn on their DC-DC during inrush causing problems.
Suggested Solution
Add the following to section 33.3.7.3
"PDs shall not draw more than the maximum current allowed by a PSE during inrush as outlined in section 33.2.7.5"
Add the following to section 33.3.7.1 at the end of second paragraph.
"The turn off voltage Voff applies both during power on and after power on"
Thanks
Kousi