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UCC38C55: Buck HV - 1280W

Bastien Bertrand
Prodigy 165 points
Part Number: UCC38C55
Other Parts Discussed in Thread: UCC28881, UCC28C55

Tool/software:

Hello TI,


Do you have a controller for a buck converter to convert from 300VDC to 115VDC? Please do.

Is it possible to supply a component like the UCC38C55 with a different voltage than the input supply?

Thank you in advance.

  • 0
    TI__Guru 73495 points

    Hi,

    Yes, you can look at UCC28881. 

    UCC28C55 VDD pin can be biased from a higher voltage than VDD need then using a LDO to obtain the VDD voltage from that high voltage so a higher voltage than VDD as input voltage can be used for the converter.

  • 0 in reply to Hong Huang
    Prodigy 165 points

    Hello,

    The UCC28881 won't do the job. I need a non-isolated converter that can convert a voltage between 115V and 300V to 115V with a current of 11.13A.

    We proposed an LLC to our customer, but he found it too heavy (500g) and bulky (30 cm X 10 cm) for his application where he needs a product between 2kg and 3kg, taking into account this card.

    I wanted to check with you whether it's possible to use a PWM chip to run a buck converter for its characteristics, to potentially save space and surface area. This is the reason for my second question in my last post “Is it possible to supply a component like the UCC38C55 with a different voltage than the input supply? “. The PWM chip may be different from the one mentioned above. The idea is to find a lightweight solution that can meet the customer's problem at the expense of performance. 

    Do you have any advice or expertise to share with me?

    Have a nice day.

  • 0 in reply to Bastien Bertrand
    TI__Guru 73495 points

    Hi,

    UCC38C55 is ok to do but need a high side driver, gate drive transformer to drive the high side switch.

    LLC 500g = 0.5kg which is lighter than 2kg or 3kg.

    It looks something needs to clarify.

  • 0 in reply to Hong Huang
    Prodigy 165 points

    I apologize for my lack of clarity, but there is equipment with other electronic cards. With these board dimensions and board weight, the equipment would weigh 5 kg. The idea would be either to reduce the size or weight of the board with another topology.

    Also, I wanted to check with you whether 500g - 600g for 1200W for an LLC was reasonable.

  • 0 in reply to Bastien Bertrand
    TI__Guru 73495 points

    Hi,

    It sounds reasonable 1200W LLC weight 500g. But I do not have much experience on the weight per watt. I suspect a buck may not help reduce the weight much since it is also a 1200W buck. There will be trade-offs between bigger heavier heatsinks weight (due to hard switching) in buck and less heavier in LLC (ZVS).