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TMUX1134: Ringing and Overshoots

Deepak Sharma
Prodigy 235 points
Part Number: TMUX1134

Hi TI,

We are observing massive ringing and overshooting effects (PFA). What compensating techniques can we utilize to flatten the transient behavior across the resistive load?

The precise voltage of 1 V for 100 nsec interval across resistive load needs to be applied through SPDT, please follow Figure 3 for reference.

Does the noise levels at select pin affects the source to drain signal of SPDT? Say how about if select pin is getting oscillatory (random noise of 200 mV) signal from 4.8 V to 5 V?

  • 0
    TI__Genius 10552 points

    Hi Deepak,

    Are you getting ringing when switching from high to low or vice versa? One possible solution is to place a capacitor to ground at the drain pin of the switch. The capacitor value will vary with the amount of overshoot, but may be on the order of 100pF to 0nF. Additional capacitance will lower the effect of overshoot, but also impacts timing and settling requirements of the system. We have an FAQ on the topic of ringing and overshoot.

    Looking forward to your response here.

    Thanks!

    Alex

  • 0 in reply to Alex Vish
    Prodigy 235 points

    Hi Alex,

    Yes, we are getting ringing when changing the voltage from 0 to 1 and vice versa. Placing a capacitor to the ground at the drain pin will kill the required pulse integrity. Any other solution would you propose?

    Thanks and Regards

    Deepak

  • 0 in reply to Deepak Sharma
    TI__Genius 10552 points

    Hi Deepak,

    Were you able to examine if any of the other tips in the FAQ help first?

    Items such as:

    • Keep the input lines as short as possible to reduce parasitic inductance and capacitance.
    • Use a solid ground plane to help reduce electromagnetic interference (EMI) noise pickup.
    • Do not run sensitive analog traces in parallel with digital traces. Avoid crossing digital and analog traces if possible, and only make perpendicular crossings when necessary.
    • To reduce reflections due to traces turning corners, the best practice is to round the edge to keep the width of the trace consistent.
    • Match load impedances with source impedances to minimize signal reflections

    Regards,

    Alex 

  • 0 in reply to Alex Vish
    TI__Genius 10552 points

    Hi Deepak,

    It's been several days now. Just wanted to follow up here!

    Regards,

    Alex