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PMP6712 FULL BRIDGE DC DC CONVERTER

KADIR ARI
Prodigy 70 points

I have assembled PMP6712 UCC28950 1.6 kW 54V full bridge converter.

When converter is run in a few second, Q5-Q6-Q7-Q8 are broken.

Why are mosfet group fault? And they are temprature over?

  • 0
    Genius 3295 points
    Hello Kadir,
    Sorry to hear about your SMPS. I hate it when that happens to me, and it does. Did you remember to attach the heat sinks? If you replace the MOSFETS and run for a few seconds can you measure voltage spikes on the switching nodes? Do you have the recommended layout? I would apply a fan and a big heat sink and try to measure the voltage waveforms to make sure the gate drives and the MOSFETS are operating correctly. Then I would check the snubber. Are they the right components. Are you starting up under full load? Maybe you have a high inrush current.

    Good luck,
    -Chuck
  • 0 in reply to Chuck Sampson
    Genius 3295 points
    You may also be oscillating. Make sure your compensation components around the U19 are correct. Your design uses a buck snubber. Make sure the IC U15 is working . You can check that before you power up.
    -Chuck
  • 0
    Prodigy 70 points
    Thanks Chuck,
    I'll check U15 and U19.