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What's the reference schematic for UCC28600 Design Spreadsheet?

W.H. Liu
Intellectual 325 points
Other Parts Discussed in Thread: UCC28600

Dear,

1. I try to use "UCC28600 QUASI-RESONANT FLYBACK CONTROLLER (Rev. J)", Excel Spreadsheet, for AC/DC Converter application. But I can't find out whom the recommended COMPONENT VALUES reference to. What EVM does this spreadsheet base on?  Could you provide me that schematic?

2. What is the optimal de-rating percentage of switching MOSFET?

3. If I would like to design a transformer based on calculated with this spreadsheet, what considerations do I need to confirm? How do I chose core type and wire size?

Input: 85~265VAC

Output: 28V, 3A

Thanks and BR

David

  • 0
    TI__Genius 15910 points

    The Design Calculator generally refers to the schematic shown in Figure 1 of the data sheet. 

    The optimal de-rating of the MOSFET is really a question or your MOSFET manufacturer.  Some MOSFETs can ride through their maximum VDs rating very well without approaching avalanche, others not so well.  Some have more tolerance to heat than others.  sometimes you can de-rate it and not anticipate the level of the leakage inductance spike and still exceed the maximum rating.  My personal level of comfort is to de-rate by 15% and to use magnetics manufacturers that can provide transformers with less than 2% leakage inductance.  But I may be considered conservative in some circles but living on the edge in others.

    For the transformer, please refer to SLUA399 for some information.  As long as you use an inductance that is relatively close to the recommended value in the design calculator, as well as the turns ratios, so that at full load, minimum input the switching frequency stay s above 60kHz the inductance value should be okay.  Unfortunately we do not usually specify the core material or wire gauge or specific number of turns for each winding as that is left to the magnetics vendors that provide us with our magnetics and would be beyond the scope of a generic spreadsheet.  Factors such as size constraints would limit the available core and bobbin configurations, and there's always a trade off between cost and performance when it comes to core selection and winding techniques. I have printed off the Magnetic Specification sheet from the completed UCC28600 Design Calculator and provided it to a number of vendors, such as Vitec, and received good performance from what they provided.

     

  • 0 in reply to Lisa Dinwoodie
    Intellectual 325 points

    Dear Lisa,

     

    Thanks for your response quickly!

     

    The attach file is my application, but there are some issues needed your help to confirm, describe below:

    1. What is the optimal soltution to select MOSFET? What parameters do I base on to chose? Is V(over protection of BULK)?

    2. How do I tune the reflect output voltage, let it large than max.peak of BULK voltage? Is it a critical issue?

    3. For an optimal design flow, is it necessary to pass QR simulation? What is key point?

     

    Reference device:

    Rectifier: GBJ606, VF=1.0; MOSFET: SPP11N80C3, VDS=800V;

     

    BR

    Wei Hung

    4353.SLVC104I_WH.xls