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UCC256403: Suitable LLC Controller

Kuan Wei Chen (Kevin Chen)
Genius 9710 points
Part Number: UCC256403
Other Parts Discussed in Thread: UCC2897A, UCC27517A, UCC28951

Dear Team

The customer is evaluating NCP1397 for:

Vin: 44~56Vdc

Vo=380V

Fsw:100kHz

May I know what is our suitable controller and reference design?

I try to run the Webench but it didn't success.

BR

Kevin

  • 0
    TI__Expert 8210 points

    Kevin

    You are correct that the closest TI device to NCP1397 is UCC256403.

    That being said, an input of 44-56VDC is very low for a resonant LLC topology.  Typically this topology is used when the input is 380V, since the ZVS it achieves has greater benefit with higher input voltages.  I recommend that you consider another topology, such as an active clamp forward with UCC2897A.  We'll need to know what the power level is to further help identify the best topology/controller though.

    This 44-56VDC input to 380V output voltage specification is not common, so our support tools such as reference designs and simplified design calculators (such as webench) may be limited.  Our device can work at this range, so if you are having trouble with the design and are finding our online tools cannot help please let us know.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    TI__Genius 9710 points

    Dear Eric,

    Long time no see!

    How are you doing?

    Sorry for missing the output power, this case is for 100W design.

    Since efficiency is the customer's key concern, so they would like to use LLC.

    The Webench can't run the simulation for this case.

    So will you suggest the excel tool or other methods to help customers expedite the design?

    BR

    Kevin

  • 0 in reply to Kuan Wei Chen (Kevin Chen)
    TI__Expert 8210 points

    Kevin

    It looks like there is an error with the webench model that is preventing it from working at this design level.  We will work to have this corrected.

    In the meantime, you can use our excel calculator http://www.ti.com/lit/zip/sluc675 for UCC256403 to help with calculations for this design.  You can also use our SIMPLIS model http://www.ti.com/lit/zip/slum684 to verify operation before you build the design.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 10 points

    Hi Eric,

    How are you, I'm Bill Liu, a power supply design engineer in Alpha US. I have a question for you:

    UCC256403 is suitable for a 1500W DC/DC converter design?

    Thank you so much!

    Bill

  • 0 in reply to BILL LIU
    TI__Expert 8210 points

    Bill 

    UCC256403 controls a half bridge resonant LLC topology.  This topology is generally used up to about 700W.  Some are looking to push it up to about 1kW, but they require external gate driver like UCC27517A to insure that the larger FETs are turned on/off fast enough.

    At 1.5kW, the performance of UCC256403 will be limited.  We recommend that instead of this device you consider our phase shift full bridge (PSFB) controller UCC28951.  This controller/topology also achieves ZVS, which enables high efficiency, but uses a full bridge instead of a half bridge so there is better utilization of the transformer.

    Best Regards,

    Eric