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ADC3424: LVDS DCLK transition time issue

菊井 良則
Prodigy 130 points
Part Number: ADC3424

I'm worry about transition time issue of ADC3424 LVDS signal in our equipment.

Could you check attached file and answer my 2 questions in the end of the document?

Thank you.

Yoshinori Kikui

ADC3424 LVDS DCLK transition time issue.xlsx

  • 0
    TI__Expert 5420 points

    The people that did that datasheet and collected the data are no longer here, so we do not know why they spec'd the rise/fall time at +/-100mV on the LVDS output. 

    Many parts labeled as LVDS are faster than the 644 spec but still work in the system.  The original intent of the spec with 260ps rise times was the minimize the overshoot/undershoot which you can see on your scope plot doesn't occur.

    Regards,

    Geoff

  • 0 in reply to Geoff Roth
    Prodigy 130 points

    Geoff-san,

    Thank you for your answer.

    It seems that you don't strictly adhere the 644 spec(260ps), but you said it has a track record in this design.

    Then, I want to add the question.

    According to the 644 specification document, it is noted that 260ps spec is set to minimalize 'adverse effect of switching noise'.

    Can I remove all elements of concern about this 'adverse effect of switching noise' by controlling signal undershoot/overshoot with oscilloscope?

    Thank you.

    Yoshinori Kikui

  • 0 in reply to 菊井 良則
    TI__Expert 5420 points

    Yoshinori-san,

    It depends on what your receiver can tolerate.  You should check with that vendor but it appears from the screen shot that you have no over or undershoot.

    Regards,

    Geoff