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UCC25800-Q1: ucc25800 not working, giving OCP2 fault at starting , even at no load

Raja Saha1
Prodigy 40 points
Part Number: UCC25800-Q1

Hi All,

OCP2 fault is coming , even there is no load. I am confirming the OCP2 fault, by seeing the waveform at Fault pin.

We are using this IC for gate driver bias supply generation.

Input is 12V, & expecting output is 23V.

WE are using Wurth P/N 750319831

At starting only, we are getting this fault & no output is generated.

Also, wrongly in our schematic, this transformer was reversely connected. However, now we have changed the resonant frequency ( 408kHZ) we have tuned the resonant cap as 33nF.

Please help. Please revert back if any other data is required.

Regards

  • 0
    TI__Expert 7900 points

    Hello Raja,

    Can you provide a schematic for analysis?

    Also, how did you correct the "reversely connect" transformer, cut-and-jumper with external wiring?  The OCP2 fault is only filtered for 100ns and is 5x the OCP1 setting.  If you're getting an OCP2 fault there is a serious issue.  I would doube-check all connections (and components) after fixing the transformer connection problem.

    Regards,

    Eric

  • +1
    Prodigy 40 points

    Hi Eric,

    The problem is resolved now.

    As I told, the primary & secondary side were swapped, i.e., we had to give our input 24V supply to the side, which we had thought as output earlier while designing.

    Hence the resonance inductor, position changed for primary to secondary, which due to turn ratio, changed the values & hence resonant frequency was completely changed.

    Now by tuning the resonant capacitors & tuning the frequency we are somehow operating near to resonant frequency, which solved the current spike & problem.

    Hope it clears.

    Regards