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I found the below attached circuit of the TPS54560 4.5V to 60 V input, 5 A step-down converter.

It is supposed to give an output of 10.8 V but when I simulate it I can't get more than 1.5V or 2V.

I'm pretty sure I'm doing something wrong here but not sure what it is.

Does anyone know what might be going wrong?

P.S. I updated the images with nodes names!

schematic

sch

This is an updated simulation of the circuit and its obvious that I got a better results after I set the simulator to run longer time (I set it to be .tran 100m) based on the valuable recommendations from JRE and The Photon. As shown in the updated image, it took an hour and half to reach ~9V.

enter image description here

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    \$\begingroup\$ Please name your nodes so we don't have to guess which nodes are "n0002" and "n0007" in your schematic. \$\endgroup\$
    – The Photon
    Commented Apr 27, 2019 at 14:37
  • \$\begingroup\$ Can you let the simulation run longer? Your simulation runs less than 1 millisecond. Hardly time to really do much. \$\endgroup\$
    – JRE
    Commented Apr 27, 2019 at 14:52
  • \$\begingroup\$ @JRE, Thanks for the hint JRE, I got a better results now, I updated the simulation image! \$\endgroup\$
    – user186623
    Commented Apr 27, 2019 at 17:26

1 Answer 1

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Assuming n0002 is the output, you may just have to wait a long long time for the simulator to simulate the complete turn-on transient.

It's even possible for the simulator to stall on certain switching circuits. How to avoid this is fairly tricky to predict. Given this is a TI part and an Analog Devices simulator, this kind of hang-up is more likely.

You should try using TI's simulator (TINA-TI) instead. From the WebBench tool where you made your first schematic image, you can just click on an "export" button to generate the schematic for TINA-TI. But even that's no guarantee of success, as switching circuit turn-on transients can simply be difficult to simulate.

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  • \$\begingroup\$ The Photon, I truly believe that you nailed it! I kept simulation for longer time and I got a better output but it hanged-up at 5.5V! WOW! So, in this case should I stop at this point and assume that everything is okay and go ahead and build the actual hardware circuit? \$\endgroup\$
    – user186623
    Commented Apr 27, 2019 at 14:55
  • \$\begingroup\$ Did it hang at 5.5 V or did it just reach the end of the time you asked it to simulate? I would run the simulation long enough to observe any overshoot on start up, and also simulate a load transient (have a current source at the load that makes a small step after the output has stabilized) to check stability. \$\endgroup\$
    – The Photon
    Commented Apr 27, 2019 at 14:59
  • \$\begingroup\$ No, it hanged at 5.5V. I'm asking for 10.8V. I'm running it at 100m now and will wait and see! \$\endgroup\$
    – user186623
    Commented Apr 27, 2019 at 15:02
  • \$\begingroup\$ Did you try the simulation within WebBench? LTSpice really isn't the ideal tool for simulating TI parts. \$\endgroup\$
    – The Photon
    Commented Apr 27, 2019 at 15:06
  • \$\begingroup\$ I updated my posting and got a better results! No, I didn't try it through Webench yet, but definitely I will try it there as well! The issue is I will need to attach more converters to this system and have a multi rail power supply and I thought that I can do it in LTSpice and simulate The whole design as one piece that consists of multiple converters which is something I cannot do in Webench. \$\endgroup\$
    – user186623
    Commented Apr 27, 2019 at 17:24

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