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UCC2897A: About the use of UCC2897A

Jeff_Liu
Prodigy 150 points
Part Number: UCC2897A

Hello,

I want to use the UCC2897A in the range of 28~160VDC, my design is as the below figure.

Can you give my some advices to improve it? Whether my design fit for the voltage range?

 

  • 0
    TI__Mastermind 31580 points

    Hi

    The biggest challenge here is the wide input voltage range, 28V to 160V, 1:5.7.

    You need to design for max duty cycle at low line, 28V so DMAX is about 65% for example, so at 160V the duty cycle will be about 11.5%. The narrow duty cycle at 160V will give very high RMS currents and the efficiency is likely to be low due to the high RMS losses in the magnetics and mosfets.

    The other disadvantage is that the mosfet devices need to be rated for high voltage for 160V but also need to be low rds-on for the high current at 28Vin.

    A two stage approach with a boost stage to boost to 160V first and then use the active clamp to step down from 160V and run it a reasonable duty cycle like 55% using the transformer to step down the voltage might be a better approach.

    Regards

    Peter