LM5157-Q1: LM5157

Hi Rayees,

Thanks for your interest in the LM5157 device.
I am sorry to hear that you are encountering very long simulation times.
It is possible to reduce simulation time by changing the settings as you already performed, but please be aware that you may have lower accuracy for your results. If simulation time is reduced too much, simulation results may become un-usable.
You can read about the specific simulation settings under Help -> Documentation. On the left side of the help window pop-up, click the menu (3 lines in a circle) to open the reference guides.

Best regards,
Niklas

Hi Niklas,

Thank for your reply. But, i am not receiving any output after completing the DC Sweep. In Help-Documentation, i am getting below page. which one i have to refer.

Regards

Rayees K.E

Hi Rayees,

Thanks for the feedback. It seems they have changed the help document layout, so I have to get familiar with the new design myself. Sorry for the inconvenience on this.

Based on simulation settings, you already took the correct steps in reducing the  PTRANABSTOL and PTRANVNTOL values.
Another alternative setting would have been to increase the SPEED_LEVEL value, but the result should be the same here.
Other FAQ thread in e2e recommend the same approach:
https://e2e.ti.com/support/tools/simulation-hardware-system-design-tools-group/sim-hw-system-design/f/simulation-hardware-system-design-tools-forum/1038001/faq-pspice-for-ti-my-simulation-fails-to-converge-and-says-info-orpsim-16594-to-improve-pseudotransient-convergence-and-performance-set-following-options-ptranabstol-1e-5-ptranvntol-1e-4?tisearch=e2e-sitesearch&keymatch=faq%3Atrue

As I understand, the main issue is that the DC sweep does not return a result at all.
I do not see any problems in your test profile, so the source of the error is unclear for me as well.
Do you see a simulation window opening after the start of the simulation, any error message, or does it just close after running the simulation and nothing happens?

Best regards,
Niklas

Hi Niklas,

Thank u for your reply.

Yes, simulation window is opening and it's showing the simulation is in progress, After the completion of the simulation it's showing error as below,

There are no data values in section number 1, ignoring this session.

Next, Simulation failed.

Regards

• Rayees

Hi Rayees,

Thanks for the description.
Have you placed probes before starting the simulation?
TI has created a video series to guide through tool as DC Sweep or AC analysis. The videos are very short and simple, but it might be a good starting point to make sure all simulation settings are correct.
https://www.ti.com/de-de/video/6162507020001

Best regards,
Niklas

Hi Niklas,

Thank you for reply.

Yes, i have placed the voltage probe in Input and output to see the graph before the simulation run.

I feel this is again the problem with LM5157 Model. I have tried with smaller circuits, and it was working fine.

Regards

Rayees K.E

Hi Rayees,

We never got that feedback before, so this is interesting that a DC Sweep works for simpler circuits, but not on the LM5157 model.
Can you give more background on the what signals need to be observed during DC Sweep and what this measurement data is required for?

We may find an alternative way to get the device behavior information you need.

Best regards,
Niklas

Hi Niklas,

I am doing the SEPIC converter simulation and varying the input voltage from 8.5V to 22V with an increment of 1V, so i want to see the variation of output voltage with respect to input, same i have to do for load current as well as temperature variation also. I kept probe at Vin and Vout and run the simulation, but after completion of the simulation i am not getting any result and showing the simulation is failed.

Regards

Rayees K.E

Hi Rayees,

Thanks for the clarification.
I can already say that the model does not simulate temperature, so it is not possible to perform any temperature related simulations.
As also no component variances are implemented in the model, all values are set to the typical values of the electrical characteristics of the device.
For data like this, I can recommend to request a sample of our LM5157 SEPIC EVM and measure voltage ripple, stability and temperature behavior on a physical board.

If you still prefer simulation data, would you be willing to share your simulation model files? I can offer to review the design and see if I can recreate the error.

Best regards,
Niklas