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UCC28950: DC/DC reference design

James Su5
Expert 1340 points
Part Number: UCC28950
Other Parts Discussed in Thread: LM5045, UCC28951, PMP9219, LM5046

My CTMR need Isolator DC12V to DC 24V / 50A and Isolator DC 24V to DC 12V / 100A solution, I think UCC28950 Should be able to meet, pls help to comment, thanks !

Thanks and Best Regards

James Su

  • 0
    TI__Mastermind 26215 points

    Hi James,

    Thanks for your interest in UCC28950. Phase shifted full bridge is reasonable for 1.2kW. Just to clarify, are 12V to 24V/50A and 24V to 12V/100A two separate designs? I have asked my colleague to take a look at your question in greater detail.

    Best Regards,
    Ben Lough

  • 0 in reply to Benjamin Lough
    TI__Mastermind 25570 points
    Hi James

    I'd agree with Ben that the PSFB is a reasonable solution and the UCC28950 is the best option for that topology -
    At such low voltages there is little if any benefit from ZVS so this simplifies the power train design a little.

    If you have more information about the specification then please let me know.

    Regards
    Colin
  • 0 in reply to Colin Gillmor
    Expert 1340 points
    Hi Colin,

    Base on PM9219 reference design and plan LM5045 change to UCC28951 + UCC2771x , please help to comment it's can meet DC12V to DC 24V / 50A and Isolator DC 24V to DC 12V / 100A solution spec request , thanks !

    Thanks and Best Regards
    James Su
  • 0 in reply to James Su5
    TI__Mastermind 25570 points
    Hi James
    I cannot find the PM9219 reference design, can you double check it and if possible include a link ? -
    Regards
    Colin
  • 0 in reply to Colin Gillmor
    Expert 1340 points

    Hi Colin,

    Sorry, it;s PMP9219 as below.PMP9219_schematics.pdf

    thanks !

    James Su

  • 0 in reply to James Su5
    TI__Mastermind 25570 points
    Hi James

    Yes, you could use the same basic schematic. At these low voltages the ZVS feature of the Phase Shifted Full Bridge won't gain you much in reduced losses so I'm not sure what is the reason behind the change. Anyhow, you can use the UCC28950 or the LM5046 with integrated drivers may be a simpler solution.

    Be careful NOT to parallel the switching MOSFETs and SRs as shown in the schematic - Q1, Q2 for example. There is a possibility for destructive high frequency, high amplitude oscillations to build up between the gate and source as the devices switch. This is due to parasitics in the devices and in the layout. The best solution is to either use separate drivers for each device or to use low value gate resistors in each gate - and also make the layout of the two devices as similar as possible with low parasitic source inductance in particular.

    The power devices may need to be uprated to carry the added current. I have not been able to find the original documentation for the PMP9219 so I don't know its power and current levels.

    Regards
    Colin
  • 0 in reply to Colin Gillmor
    Expert 1340 points
    Hi Colin,

    The two specifications are recommended one power stage to finish or made two power stage in parallel ?
    please help to design transformor , thanks !

    Thanks and Best Regards
    James Su