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WEBENCH® Tools/TPS82740A: Webench Startup simulation time scale

Part Number: TPS82740A
Other Parts Discussed in Thread: TINA-TI, , TPS62740

Tool/software: WEBENCH® Design Tools

Hey, I'd like to change the limit time for the startup simulation, but I can't see any way to do so... is it because my glasses are so bad, or, is it really not possible, or, is the capability hidden, or?

I'm running a simulation with a known-wrong inductor, and the 82740 should be going into pass-through mode, but it's switching, as the Vout is ramping up... problem is, the sim cuts off before Vout gets high enough to reach a point where the Vin is close enough to Vout to go into pass-through mode... It's also, from a design view, a bit strange that  the device does not go into pass-through immediately; I'm guessing that it's looking at Vout, and Vout is still well below Vin, at start-up, but the device should 'know', based on Vsel, that Vin is too close to the selected Vout, and just go straight to pass-through, it seems.

Anyway, the main question is how I change the startup time to a greater value??

  • Hi Barry,

    Please note that there is no option to change the simulation time on Webench.

    However you can run the simulation in local machine and change the sim time using TINA-TI tool by performing  the sim export  as shown below.

    Thanks and Regards,

    Atul

  • Thanks, Atul, but, sadly, our corporate IT does not allow me to install 'foreign' programs...and, my home machine is a Mac... can I export to LTspice??  ;-)  ??

  • Hi Barry ,

    Unfortunately we do not support LTspice.
    You can try running the simulation on Pspice by exporting to Cadence OrCAD.

    Thanks and Regards,
    Atul
  • Unfortunately we can not use Tina at work, due to restrictions on programs from outside our IT firewall... maybe it would be nice to add the feature to Webench, or, at least, ensure that the sim runs to a stable state... maybe it just terminated because of the very long sim time, since I had purposely set the inductor value very low?
    So, not resolved, but not the biggest deal, either.
  • Hi Barry,

    Could you please share the design with us so that we can take a deeper look into it.

    This device (TPS82740A) doesn't have external inductor. So could you please let us know if you are referring to same device.

    You can run the steady state simulations using the below dropdown.

    Thanks and Regards,

    Atul

  • sorry... I had switched over to the 'parent' device, TPS62740...I had set it up for 2.5 V in from the Startup V source, and 2.5 Vout selected, and a 100 nH (!) inductor... basically, I wanted to see the Startup behaviour with small, or no, inductance, when Vout was selected to be the same as Vin, which should cause a switch to the bypass mode. It seems, however, that the device does not have the 'intelligence' to compare the selected Vout with Vin, and then go to bypass mode immediately, rather, it seems to start switching in 'soft-start' mode, and it does not get into bypass mode during the Startup period allowed in the sim...It's an outlier case, admittedly, but I wanted to exercise this bypass mode in a Startup mode...
  • Could you please create the design and share it with us using the steps mentioned earlier.

    Thanks and Regards,
    Atul
  • Hi Barry,

    We didn't hear anything from you. Hope it is resolved.
    Please revert back if there are any issues.

    Thanks and Regards,
    Atul