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UCC2800-Q1: Is there a way to limit the maximum duty cycle limit?

Lauren Mayfield
Expert 7445 points
Part Number: UCC2800-Q1
Other Parts Discussed in Thread: UCC2800, UC3842A, UC3842

Hi HVC team,

Question above. The max duty cycle is 100%, is it possible to limit to 80% (for example)?

Thanks,
Lauren

  • 0
    TI__Expert 7445 points

    Is there an update?

    Thanks,

    Lauren

  • 0 in reply to Lauren Mayfield
    TI__Genius 13660 points

    Hi Lauren,

    Sorry for the delay.

    Refer figure 5 and figure 9 in the datasheet,  We can limit the maximum duty cycle by regulating the dead time.  But it can only realize a very small range regulation. I don't think there in a good solution to limit maximum duty cycle for UCC2800. 

    The duty cycle of UCC2800 cannot be easily modified by adjusting RT and CT, unlike the UC3842A family. The maximum duty cycle limit is set by the ratio of the external oscillator charging resistor RT and the internal oscillator discharge transistor on-resistance, like the UC3842. However, maximum duty cycle limits less than 90% (for the UCCx802 and UCCx803) and less than 45% (for the UCCx804 and UCCx805) can not reliably be set in this manner. For better control of maximum duty cycle, consider using the UCCx807.
    Regards,

    Teng