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Part Number: UCC28881
We use UCC28881 for a 3 channel output PSR flyback application, which is used as auxiliary power for a totem pole PFC. When the PFC starts work, we find UCC28881 may shutdown, which cause output voltage drop and MCU reset. The normal and unnormal waveforms of 5V output and switch node as below.
What may cause this shutdown?
I am not sure why the UCC28881 is shutting down when the PFC is turning on. Do you have a schematic that you can share?
The device does have two protection feature that will shut it down.
1. Thermal shutdown with a junction temperature of 138.5 deg C typical
2. Short Circuit Protection
a. If peak current limit is hit before tmin has timed out 200 ns typical.
b. I would check the transformer current with a current probe to make sure it is not saturated.
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In reply to Mike O':
I will send you the detail by mail. Thanks!
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