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UCC2897A: PMP6547 reference schematic queries

Neo.Wang
Intellectual 950 points
Part Number: UCC2897A
Other Parts Discussed in Thread: PMP9720

Hi TI experts,

For PMP6547_REVB reference design, what's the turn ratio of the transformer?

For wide input range, the secondary FET is having high stress, if still go with self-driven, any thermal measurement on the Discrete driver Q8 and Q9? Will thermal be a concern?

Thanks

Neo

  • 0
    TI__Mastermind 32975 points

    Hi Neo,

    The turns ratio is approximately 0.9:1. It is difficult to maintain adequate gate drive over 3.33:1 input voltage range and over the entire load current range. The thermal images shown in the PMP6547 are only given for VIN=48V, IO=10A and you can see the secondary side at 75C (50C above ambient). Operation at VIN=60V will be worse. It may be worth looking at designing a crude regulator off the transformer secondary and using gate driver ICs for each of the SRs, as shown in PMP9720

    Regards,

    Steve M