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UCC28220: UCC28220 maximum duty cycle

David Woo
Prodigy 530 points
Part Number: UCC28220

I have one question about the max duty cycle setting on UCC28220.

How could the Dmax be limited to <50% for 2 FET Forward operation?

According to the equation, the Dmax can’t be <60%, how can I set the Dmax to be <50%?

  • 0
    TI__Expert 3095 points
    Hi David Woo,
    I suspect that this is not possible with this part.
    Equation 2 of the datasheet suggests that a 50% duty cycle would require an oscillator duty cycle of zero.
    One option would be to use an external flip-flop and gating + drivers such that only every second pulse is passed to the switches. In this case you should be able to achieve a maximum duty cycle clamp of 45%. (90% coming from the controller but only every second pulse going to the switch).
    Another option would be to use an alternative controller with a 50% duty cycle clamp incorporated.
    Thanks
    Joe Leisten