Hi
all,
I
would like to start a discussion regarding the MPS signal in the spec.
It
looks that the text may not be clear and concise and may lead to wrong
interpretations.
See
attached below a Table that I have generated during an attempt to translate the
current text in page 68 lines 3-12 and The table 33-13 lines 12 and 16 to a
simple valid and non valid MPS signatures and the required action as a result
and it looks that we need to discuss how we make it simple and easy to test.
I'll
appreciate your inputs and thoughts.
In
addition see below my suggested remedy for clearer text that covers all
combinations.
-------
Suggested
Remedy:
Replace
33.2.11.1.2 with the following text:
33.2.11.1.2 .1 MPS
Component is present
A
PSE shall consider the DC MPS component to be present and shall not remove
power from the port in the following cases:
a)
if the DC current is greater than or equal to IMin2 max or
b)
if the DC current is greater than or equal to IMin2 max for at least TMPS
every
TMPS + TMPDO, as defined in Table 33-11.
The
current level during TMPDO may be lower than IMIN2.
This
allows a PD to minimize its power consumption.
33.2.11.1.2 .2 MPS
Component is present or absent
A
PSE shall consider the DC MPS component to be present or absent and may not
remove power from the port in the following cases:
c)
if the DC current is within IMin2 range or
d)
if the DC current is within IMin2 for any t=Tx value, every Tx + TMPDO.
The
current level during TMPDO may be lower than IMIN2.
33.2.11.1.2 .2 MPS
Component is absent:
A
PSE shall consider the DC MPS component to be absent and shall remove power
from the port if the DC current is within the range of IMin1 for t>TMPDO
-------
Thanks
Yair
Darshan Yair
Chief R&D Engineer
Analog Mixed Signal Group
Microsemi Corporation
Neve Ne'eman Industrial Zone
Hod
Tel: +972-9-775-5100,
Cell: +972-54-4893019
Fax: +972-9-775-5111
E-mail: <mailto:ydarshan@xxxxxxxxxxxxx>.