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UCC29950: LLC config problem

tian wu
Prodigy 20 points
Part Number: UCC29950

Dear TI power design support team:

    Recently several months, I was developing an AC-DC power project(220Vac input, 30V,30A output), I select UCC29950 as controller for this design and reference to TIDA-00704(an 24V/330W solution).

    I start with TIDA-00704, and confirmed it is worked. and then by Ucc29950 calculator, I changed the output power to 900W(30V,30A), got a set of new design parameter, and then made a new sample board. major difference is LLC transformer.

   But when I tested the new board, I found the LLC and PFC MOSFET is very easy to blow up (even include UCC29950). 

   After tried many adjust,LLC loop still not work

  • 0
    TI__Mastermind 25570 points

    Hello

    First: my apologies for the delay in responding to you.

    Did you change the PFC inductor too?

    Will the board work at a lower power ? - for example will it work at 300W. If it does then we can start to look at the voltage waveforms at the PFC and LLC MOSFETS ?

    Can you post the voltage waveform at the drain of the PFC MOSFET when the duty cycle is close to maximum, when it's at about 50% and when it is close to minimum (the duty cycle changes through the line cycle)

    I'd also like to see the voltage waveform at the drain of the bottom LLC FET

    If the board doesn't work at lower power then the first thing I would check is the PCB layout. If you send me the layout Gerber files or the original files I will review them. I would also need the schematic. If you don't want to post them here you can send them directly to me at  colingillmor@ti.com

    Regards
    Colin

  • 0 in reply to Colin Gillmor
    TI__Mastermind 25570 points

    Hello

    Thanks for sending the schematic and layout files. I've reviewed them and made some suggestions on how to proceed to solve this issue. We can continue to communicate via email so I'm going to close this thread.

    Regards

    Colin