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UCC256404: About the operation when startup fails

user3266596
Prodigy 90 points
Part Number: UCC256404
When the input voltage is applied with the load current set slightly increased, the output voltage may rise halfway but may not start.
The rise time when it can be started is about 20 msec.
It is considered that BW OVP, OVP1 and OVP3 are not operating in terms of the measured waveform.
If you can't start it, can you predict how it's stopped?
At the time of soft start, the threshold value of OVP1 changes, but are there any changes such as OVP2 and OVP3 stopping functioning?
  • 0
    TI__Genius 9790 points

    Hi, there 

    There is no OVP1/3 on BW pin, only OVP function on BW pin. 

    The fault of UCC256404 conclude OVP on BW pin, and OCP1/2/3 on ISNS pin, and UVP on BLK pin. Any fault is triggered, UCC256404 will be restart every 1s.

    Could you check the waveform of VCC/LO/BW/ISNS to confirm which fault is triggered?

    Yunsheng