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UCC28704: SMPS design not working as expected

Neel Shah101618
Intellectual 550 points
Part Number: UCC28704

Dear TI team,

We have designed an SMPS based on the reference circuit provided by TI. We are using a custom transformer which is tested by the manufacturer. The test report is attached here along with the datasheet. This transformer was designed based on the RENCO transformer details.

We are trying to turn the SMPS on we don't get any outputs on the output terminals.

We need your support on how to test it out.

Can you please guide us?

Thanks

Ambimat Team

  • 0
    TI__Prodigy 590 points

    Hello,

    I have assigned this to an expert on the part. Someone should be in contact with you shortly.

  • 0 in reply to Pye Naing
    TI__Guru* 77495 points

    Hello,

    Number one reason why PSR controllers will not turn is due to aux winding ringing noise triggering OVP.

    1. Please refer to page 13 of the data sheet
      1. OVP can be triggered from the end of TLK_RESET to then end of tDMAG.
      2. If OVP is tripping you may be able to use a snubber to dampen the ringing.
      3. There should be less than 100 mV of ripple on the aux winding at the sample point.
    2. The following link will bring to an application note for troubleshooting PSR flyback controllers.  You should find this information helpful. 

    Regards,