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UCC27511A-Q1　Question

Masazumi Ishii
Genius 3945 points

hello

I have a question about UCC27511-Q1

1,How many is the minimum pulse width?
2,How many is the maximum pulse width?
3,Is it subject to restrictions of a duty?

Thank you.

  • 0
    TI__Expert 7395 points
    Ishii-San,
    Normally you need to have a min pulse width greater than the worst case prop delay so 30ns or greater and you can test quickly but this device should accept DC (100%duty) input. Let me confirm with the driver team so by design we're confident in this.
    Regards
    John
  • 0
    TI__Mastermind 20950 points

    Hello Ishii-san,

    The minimum pulse width to see a response from the driver is related to the worst case input to output prop delay, shown as tD2 in the datasheet. 30ns is the worst case propagation delay so the output will response within 30ns to the change on the driver input pin.

    For the maximum pulse width: the driver can operate all the way to DC input; the output will be high as long as the input is high, except for the short propagation and rise or fall times.

    For duty cycle limitations: the limitations of the driver timing is the combination of propagation delay(s) and rise and fall times. The duty cycle will be based on the converter switching period, and the driver timing limitations.

    For example: minimum duty cycle limitation based on 30ns time limitation and 500kHz: tD2/(1/Fsw) =Td2 x Fsw, 30n x 500k = 1.5%.

    The maximum duty cycle, other than DC will be 1-(tD2 x Fsw) or 1-1.5%= 98.5%.