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Hello, The IEEE 802.3at Vport ad hoc needs your help collecting
data that will help establish new transient constrains on the MDI. Please
forward this email to system designers within your companies that will help
with this effort. If more details are required, they can contact me
directly. We would appreciate getting this data before the end of
December. Thanks, Fred Schindler Technical Leader CISCO Systems M/S SJ-19-3 Tel. (408) 525-9859 ------------------------ Details --------------------- IEEE 802.3at Vport ad hoc presentations January 2006 http://grouper.ieee.org/groups/802/3/at/public/jan06/schindler_1_0106.pdf May 2006 http://grouper.ieee.org/groups/802/3/at/public/may06/schindler_1_0506.pdf Conclusion
of Vport static discussion http://grouper.ieee.org/groups/802/3/at/public/may06/schindler_3_0506.pdf Vport
Static & Dynamic Vport Estimator spreadsheet V9 (XLS format) July 2006 http://grouper.ieee.org/groups/802/3/at/public/jul06/schindler_1_0706.pdf September 2006 http://grouper.ieee.org/groups/802/3/at/public/sep06/schindler_1_0906.pdf
November 2006 http://grouper.ieee.org/groups/802/3/at/public/nov06/schindler_1_1106.pdf Summary -
The static Vport
voltage is within a 50 to 57 VDC range. -
Spreadsheet v10 is the
most recent published version (September). See the “PD PSE data” for example data
submissions. -
We are investigating
keeping the PD voltage specification as is when accommodating transient
conditions. -
The channel model used
does not represent a real world system but the task force believes errors are negligible. -
There are no di/dt PD
constraints in the IEEE 802.3 specification. Goals -
Place a minimum number of constraints on the system in
order to ensure system interoperability. -
We expect to produce a PD di/dt constraint. -
We expect to produce a PSE voltage droop constraint (below
the static port voltage for a specific duration). Please send scope images captured and your system
setup details. PD data required Please use a short cable to connect
the PD to a low output impedance supply for your tests. Operate the PD in
modes you expect higher di/dt rates. We also need data for PD DC-DCs. Load
the output and measure the Ethernet line side to capture the worst-case data.
We expect DC-DC data to provide the most reliable worst-case data. -
A model number (so that
others can repeat the experiment). Data can be kept anonymous.
Please state your preference. -
di/dt values for a
specific duration. -
Does the PD ever cross
Icut or Ilim? Please provide details if this does occur. -
How does the PD respond
to MDI voltage changes (up/down within spec.)? ex/ some PDs turnoff when
the supply droops to fast. Some draw more di/dt when the voltage is
increased. PSE data required Transients are expected for load
changes (assume all PD transition to a new load level), or supply replacement
events (backup of a failing supply). - A
model number (so that others can repeat the experiment). Data can be kept
anonymous. Please state your preference. - dv/dt
and duration. -
Details on the condition causing the transient. Ex/ load change
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