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UCC25600: Is the HB-LLC suitable for 36V 1300W

Gerald Eberahrdt
Prodigy 160 points
Part Number: UCC25600
Other Parts Discussed in Thread: UCC28070, , UCC25660

Hello,

I'm working on power source project to generate 36V @1300W from universal AC input (65-264Vac), and need some advice on what DC-DC buck stage to use following the PFC.

At this time, I'm leaning to a 2-phase interleave PFC using the UCC28070 to generate a boosted voltage to 400V.

The challenge is finding an efficient high-density topology to produce the 36V from the 400V. 

Initially I was looking at the Half-Bridge Resonant LLC and while doing my research I'm finding a barrier of 1kW for standalone controllers (non-digital core). In my research I'm noticing that above 1kW the controllers start including digital cores to "most effective way to overcome its difficulties and pitfalls".

I have few questions for the experts:

1) Is the UCC25600/UCC25660 a suitable controller for this application.

2) Why is the magic barrier 1kW for HB-LLC?

3) What are the "difficulties and pitfalls"?

4) Is the HB-LLC a good topology for 36V 1300W application

  • +1
    TI__Mastermind 44220 points

    Hi Gerald,

    To answer your questions:

    1) Is the UCC25600/UCC25660 a suitable controller for this application. *The UCC25660 will be far easier to use and design in. It has more integrated protection and is less sensitive to layout. 

    2) Why is the magic barrier 1kW for HB-LLC? *It comes down to stress on the power stage. Normally above 1kW, we recommend a Phase-Shfited Full-Bridge approach like the UCC28951. Here is a potential reference design you can look at as a starting point. 

    3) What are the "difficulties and pitfalls"? *For either approach the biggest challenge is typically optimizing the magnetics. For an LLC approach, one of the challenges is avoiding the capacitive region of operation. Our new LLC the UCC25660 has a new scheme to make this easier to avoid. 

    4) Is the HB-LLC a good topology for 36V 1300W application *As mentioned above, normally we would recommend a phase-shifted full-bridge at this power level, but an LLC can work here as well. 

    I hope this answers your questions. 

  • 0 in reply to JCHK
    Prodigy 160 points

    Thank you. This helps.