• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 532 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UCC28881: What may cause UCC28881 shutdown?

Dylan Zheng
Intellectual 1815 points
Part Number: UCC28881

Hi team,

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?

Best regards,

  • 0
    TI__Guru* 85616 points

    Hello,

    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.

    Regards,

  • 0 in reply to Mike O'
    TI__Intellectual 1815 points

    Hi Mike,

    I will  send you the detail by mail. Thanks!

     Regards,

    Dylan Zheng