• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 809 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.

UCC28950: Catch diode(D29) failure in my 1KW Power supply

Aneesh TS
Expert 1735 points
Part Number: UCC28950

Dear TI experts,

I have designed a DC-DC converter with UCC28950

My input/output specifications are 

Vin=400V

Vout=60V

Iout=17A

I have used 30uH shim inductor initially and  the power supply was working fine, but i was loosing some duty cycle, so i changed the inductor value to 10uH. Now my catch diode(D29) is failing. 

What is the impact of reducing Shim inductor(L5) value in catch diode D29 in my schematic?

Regards

Aneesh

Regards

Aneesh

  • 0
    TI__Guru* 86286 points

    Hello,

    Lshim has the energy that is used to achieve ZVS.  So reducing that will affect how you will achieve ZVS there will be less energy stored in it.

    I would not think reducing it would cause D29 to be damaged.  Are you shore this is what damaged that diode?

    Diode 29 and Diode 28 are uses to clamp the difference between the current in L5 and the primary of the transformer when you come out of freewheeling.

    What current level did you pick for the diodes?  They might just be under rated for current or dv/dt.  I would size the clamp diode for the maximum primary peak current just to be safe and use ultra fast diodes.

    Regards,

  • 0 in reply to Mike O'
    Expert 1735 points

    Hi Mike,

    Thank you for the feedback....

    Regards

    Aneesh