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Original question:

UCC28782: ADAPTOR+CHARGER USING UCC28782

UCC28782: LMG2610 with UCC28782

robin gangopadhya18
Mastermind 6296 points
Part Number: UCC28782
Other Parts Discussed in Thread: LMG2610, , LMG5200, LM76005

Hello:

ds for LMG2610 states that the part is meant for a[[lications <75W

Yet, nowhere can one notice where that limit comes from.

Surely, one place would be the input voltage limit: the lower it is, the higher the peak current and perhaps lower Lm also forces higher leakage thus causing higher upper GaN peak currents.

In order to satisfy the 100W limit offered under the USB C PD and adopters, it is safe to specify that the lowest input level will be 120V, not 100V.

Will that exceed any SOA boundaries?

Any comments on this will be highly appreciated..

R

  • +1
    TI__Expert 8960 points

    Hello,

    The part is intended for active clamp flyback converters. ACF, as a topology, starts to get less competitive beyond 75W due to magnetics size. Additionally, PFC is legally required for offline converters beyond 75W.

    For a 100W USB-C converter, an active PFC would be needed anyway, so the LMG2610 input voltage would be ~400V.

    If there were an application where the LMG2610 would need to operate as an 100W ACF at 100Vin, it could do it. The LMG2610 current limits are specified in section 6.3 of the datasheet.

    Thanks,

    Travis

  • 0 in reply to robin gangopadhya18
    Mastermind 6296 points

    Hello: 

    The USB C PD Specification states that there is a mode "EPR" where VBUS can be programmed to be 24,28,36, or 48V up to 240W max.

    Even at 240W, LMG2610 wont exceed its I limit.  So is that mode available using UCC28782 controller provided of course the xmfr , SR etc can handle this power all limited to 5A max output?

    Should we redesign the xmfr to accommodate this range?...we prefer designing in ac to 48V output, with a sync buck with I2C, capable of bucking from 5V to 48V!

    We have a design done with TPS5588, but that won't do of course. What other solutions do we have from TI?

    Any review of this will be highly appreciated.

    r

  • 0 in reply to robin gangopadhya18
    TI__Expert 8960 points

    Hello,

    robin gangopadhya18 said:
    Even at 240W, LMG2610 wont exceed its I limit.  So is that mode available using UCC28782 controller provided of course the xmfr , SR etc can handle this power all limited to 5A max output?

    LMG2610 can handle 240W just fine if its receiving 400Vin from the PFC stage. However, at that power level I would recommend using an LLC converter instead of ACF in order to reduce magnetics size.

    robin gangopadhya18 said:
    Should we redesign the xmfr to accommodate this range?...we prefer designing in ac to 48V output, with a sync buck with I2C, capable of bucking from 5V to 48V!

    The USB-PD controller that TI is launching later this year for 48V USB operates like you described, with a fixed DC rail being bucked to a digitally controlled lower voltage.

    robin gangopadhya18 said:
    We have a design done with TPS5588, but that won't do of course. What other solutions do we have from TI?

    If you're interested in a GaN output stage, LMG5200 + controller could be a good fit. For an Si solution, something like LM76005 could work.

    Thanks,

    Travis