
Use
Select a value higher than the nominal power in order to be able to respond to transients.
To initially setup this value, set it to twice the maximum power estimation using Equation
.
Then fine-tune it by
•
Turning on the board with the maximum load
•
Reading the input power raw value using the GUI (see
for details)
•
Setting the parameter to input power raw value + 30%
The value can be further adjusted by looking at the PFC stage transient response.
Figure 1.
STNRG011A GUI; circled in red the raw value of the input power
3.3.7
PFC pss
Size: 3 bits
Sets the PFC power during the soft-start.
Available values are:
•
640
•
1280
•
1920
•
2560
•
3200
•
3840
•
4480
•
5120
The higher the value, the higher the on-time of the PFC MOSFET during the soft-start phase.
Use
Choose the value that allows reaching the required PFC soft-start time.
The faster the soft-start time required the higher the PFC current will be.
Using a high value can lead to overshoots (the bulk voltage increases at every line cycle increase).
3.3.8
PFC pcc
Size: 2 bits
Sets the PFC reference the power during burst mode operation.
Available values are:
•
3218
UM3002
PFC parameters
UM3002
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Rev 1
page 12/42