[8023-POEP] Vport Ad Hoc Action Items
ACTION ITEMS:
----------------------------------------
PD di/dt values for shipping systems.
Maximum di/dt of PD when PD load goes from min to max?
Typical PD: Current goes from min to max in ~50uS
or di/dt = 15mA/us
This is for a current mode switcher.
A voltage mode switcher may increase current much
faster.
---------------------------------------
AC-DC di/dt demand possible (data points) while still
within specification.
AC-DC Power Supply Performance
Talked with Power-One
Typical PoE Supply (PALS)
With 50% load change
2% maximum diviation
Recovers to within 1% in 400uS
With 100% load dump, estimated that output will have:
4-6% maximum diviation
Recovers to within 1% in 400uS
-----------------------------------------
When PSE changes from 57V to 44V through a
representative channel resistance.
The PD will just look like a capacitor. Typical
values are 10uF to 100uF.
Channel resistance and inductance is of little
significance.
System will go into current limit, either at PSE or at
PD.
The amount of excess current (PSE ILimit - PD load)
will be available to charge cap.
For example:
PSE ILimit=425mA
System voltage = 48V
PD load = 12W (example) == 250mA
PD capacitor = 100uF
i=C dv/dt
dt=13V
Cap will charge in 7mS
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com