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UCC28750: Application issues.

Reed
Expert 1910 points
Part Number: UCC28750

Tool/software:

Hi Team,

Using UCC287506.

Please help review SCH file.  120W. 

Don't worry about QR detection.

Thanks.

SCH_UCC28750_2024-12-02.pdf

  • 0
    TI__Genius 12795 points

    Reed,

    Please specify your question so we can better assist. Please also share the application type and business background to us.

    Thanks

  • 0
    Expert 1910 points

    Hi Ning,

    New plan, please check if the schematic parameters are reasonable.

    Thanks!

  • 0 in reply to Reed
    TI__Genius 12795 points

    Reed,

    I didn't find anything obviously wrong. It is not reasonable to go through all the details without any business background. You will need to check all the component value using our calculator online.

    Best,

    Ning

  • 0 in reply to Ning Tan
    Expert 1910 points

    Hi Ning,

    This is the final schematic diagram,
    The DS waveform diagram and GS gate waveform diagram of synchronous rectification MOS,
    But the temperature of MOS at 24V/3A output is very high, which does not meet our expectations,
    What is the reason?

  • 0 in reply to Reed
    TI__Genius 12795 points

    Reed,

    I suggest you to overlay Vgs and Vds in the same image. The SR waveforms seem ok to me.

    What do you mean by too high temperature? Did you measure the temperature with a thermal camera? What is your expected temperature?

    Why do you use -06 variant at 100kHz instead of 01-04 at 65kHz?

  • 0 in reply to Ning Tan
    TI__Mastermind 40120 points

    Hello Reed, 

    The waveforms and the schematic do not show any problems that would account for excessively high temperature at 75% load.
    High temperature can also be due to poor heatsinking. 

    Please provide answers to the questions that Ning asked, and also check the mounting of the SR MOSFET to its heatsink.
    Is the heatsink sized correctly based on the expected maximum power loss and maximum ambient temperature? 
    If the mounting is not correct, or the heatsink is too small, then the heat can't get out of the MOSFET.  

    Can you show the calculation of the SR MOSFET maximum power loss, please?

    Regards,
    Ulrich