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UCC27211A: what is the the maximum pulse width of the input that ensure there is not output?

Harry Ma
Intellectual 2660 points
Part Number: UCC27211A

Tool/software:

Hi Team

There is a spec: Minimum pulse width that changes the output, which means if customer wants to ensure their input pulse can change the output, the input pulse width should be larger than 40ns at least.

So my question is: Is there a spec to define, if the input pulse width is smaller than *ns, the output must not be changed? 

why I ask this question is there are some noise or glitch in input side in customer side, but the width is smaller than 40ns, they wanna understand if the output will not be changed by these noise of glitches?  they want to know the maximum pulse width that will not change the output.

  • 0
    TI__Genius 14145 points

    Hey Harry,

    Thank you for reaching out with your question regarding the UCC27211A.

    There is not a spec for the minimum pulse width that will propagate an output. We only have the 40ns minimum pulse width spec as a max to guarantee that any input pulses of 40ns and greater do propagate to an output.

    It is advised to have RC filters on the inputs to help filter out any unwanted noise and provide square input waves to the input pins.

    Let me know if there are any questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    TI__Intellectual 2660 points

    HI William

    Can I think the the output pulse width will always narrow than input pulse width.

  • 0 in reply to Harry Ma
    TI__Genius 14145 points

    Hey Harry,

    The input pulse width propagates to the output pulse width with minimum pulse width distortion. So the input width and output width are expected to be the same.

    Let me know if there are further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    TI__Intellectual 2660 points

    Hi William

    How much of the bandwidth of scope should be configured when we test the ABS value?

    Why I ask this question is customer used 500M bandwidth to test VHP voltage and found there was a negative voltage spike, the voltage will less than -2V & 20ns.

    Does it have risk to damage the device?

  • 0 in reply to Harry Ma
    TI__Expert 8771 points

    Hi Harry,

    The highest possible bandwidth should be used when measuring gate driver signals. This is so very high frequency transient spikes are clearly visible.

    As long as the spikes are within datasheet specs, then we guarantee the device to operate as intended. Since the negative voltage spike is not below -2V and it is for less than 20ns, the device should be fine.

    Thanks,
    Rubas

  • 0 in reply to Rubas Khalid
    TI__Intellectual 2660 points

    Hi Kjalid

    The voltage is below that -2v but within 20ns with 500M bandwidth.

  • 0 in reply to Harry Ma
    TI__Expert 8771 points

    Hi Harry,

    If it's below -2V for any amount of time, then we cannot guarantee that the driver will operate as intended. We recommend keeping the negative spike within specs.

    Thanks,
    Rubas