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any solution to provide delay for PWM signal?

Aki Li
Genius 9735 points
Other Parts Discussed in Thread: SN74LVC1G123, SN74AHC123A, SN74LVC2G74

Customers used to achieve extra delay for the PWM signals with RC circuits, but they want to check whether we have such kinds of logic device to help them with the configurable delay, since the present method is not accurate. Could you please help check it?Thank you.

  • 0
    Guru 316690 points

    Even devices like SN74LVC1G123 use R and C to set the delay.

    It might be possible to construct a delay circuit with flip-flops if there is an external clock signal.

    What accuracy is required?

  • 0 in reply to Clemens Ladisch
    TI__Genius 9735 points

    Hi Clemens, 

    I found the ouput of SN74LVC1G123 can not follow the pulse width of the input PWM signal, and it can just provide a specific pulse. Did I miss anything?

    What does a delay circuit with flip-flops look like? Thank you.

  • 0 in reply to Aki Li
    Guru 316690 points

    On further thought, a flip-flop's clock input is not actually useful, because you needed a clock synchronized to the PWM signal. But one can use a flip-flop to store the output state:

    Use the two multivibrators in a SN74AHC123A, configured for the same delay, one triggered by rising edges, one triggered by falling edges. Connect their Q outputs to the A inputs of a second SN74AHC123A, which is configured for very short pulses. Connect the Q outputs of the latter to the PRE and CLR inputs of a SN74LVC2G74.