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SN65MLVD040: transient overshoot/undershoot

Kyson Tan
Prodigy 120 points
Part Number: SN65MLVD040

Tool/software:

Hi,

What is transient overshoot/undershoot requirement for SN65MLVD040 part? We are having trouble meeting the -0.5V to 4V abs max rating with the current parts placement, so we are trying to see how much the part can tolerate if the transient overshoot and undershoot exceed the abs max rating.

Thank you in advance.

  • 0
    TI__Guru 72821 points

    Hi Kyson,

    Do you have a scopeshot of what the undershoots/overshoots look like and the time frame of them? 

    I can try to talk to a designer to see if this there is an acceptable range/time frame that exceeding the abs max would be. 

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 120 points

    We don't have physical board to probe yet, but we are at a point where the layout is locked down. We are trying to increase the series resistor values to address the undershoot/overshoot, but this will slow down the edges and ultimately cannot meet the speed we need. So we are trying to go the other direction, reducing the resistance to meet the edge requirement and see how much overshoot/undershoot we will see. We are simulating different scenario right now. But meanwhile, could you please reach out to the designer to see if there are some voltage and time values that can be provided?

  • 0 in reply to Kyson Tan
    TI__Guru 72821 points

    Hi Kyson,

    Are you able to provide the max/min overshoots and the duration from the simulation results? I ask because these kind of questions to design without detail may not be very helpful since they could say a -2V undershoot for 1ns is okay but a -1V undershoot for 5ns may not be (I made up these numbers here but the max value and the time duration matter and there can be multiple cases where it could work by varying the duration and value).

    I'm also going to say that this device predates our internal database storage system so we may not be able to pull the design file for this, so they may not be able to check using their internal tools. This may come down to me asking a designer what they think is acceptable vs. what a reliability tool could provide. 

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 120 points

    Based on the simulated result, it looks like the worst one's undershoot peak is -615mV, and the time it exceeds -500mV is about 700ps. Will this damage the part?

    There are also some other ones that have about the same undershoot (-615mV), but shorter duration (100ps), will these damage the part?

    Thanks,

    Kyson

  • 0 in reply to Kyson Tan
    TI__Guru 72821 points

    Hi Kyson,

    I've sent the information you've asked to our design team. I'll let you know what they say when they get back to me.

    -Bobby