TPS56121: Simulation Errors

Aaron McIntosh

Part Number: TPS56121
Other Parts Discussed in Thread: LM70880-Q1

Tool/software:

Hello,

I have implemented a TPS56121 circuit for a 14V input, 12V 15A output application into Pspice for TI, designed with help from Webench. Please validate the design as I encountered errors when attempting to simulate and could not pinpoint the reason.

I have also attached some of the errors I am facing.

Thank you for your help.

11 months ago

0 Calan Elaya 11 months ago

TI__Genius 11545 points

Hello,

For your conditions of 14Vin, 12vout, and 15A, this design exceeds the duty cycle limit for the device. This is likely why errors are occurring in this design.

Webench is not able to design with these conditions.

Please try to design with different conditions and let me know the result. We can also search for a device that supports these conditions if needed.

Thank you,

Calan

0 Aaron McIntosh 11 months ago in reply to Calan Elaya

Prodigy 90 points

Hello Calan,

I repeated tests with lower voltage output conditions but the same errors remained. I am looking for buck converters with 12V 15A outputs and already identified LM70880-Q1 in parallel and designed a circuit for it prior to testing TPS56121, but swapped as it did not have dual mode modelled and I could not do any simulation tests. Do you know any other devices if I cannot resolve these errors with the given conditions?

Thank you

0 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

I am currently looking into what the errors could be caused by. After this, if it is still needed, we will look into alternate devices.

Please allow me between this week and next, to get back to you regarding the P-SPICE issues.

Thank you,

Calan

0 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

Can you share your zipped project with all the files?

Thank you,

Calan

0 Aaron McIntosh 11 months ago in reply to Calan Elaya

Prodigy 90 points

Hi Calan,

Sure.

TPS56121 Simulation.zip

Thank you.

0 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

Thank you for sharing. Please allow me some time to look into this.

Thank you,

Calan

0 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

We are currently working on this and will keep you updated.

Thanks for your patience,

Calan

+1 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

It seems what is causing the error in the PSpice simulation is an extra curly bracket that is on line 215 of the .lib file.

See below:

Once this extra curly bracket is removed on your end, save the file, and re-run the simulation and it should work.

Hope this helps.

If this helps solve your issue, please don't forget to click "This resolved my issue."

Best,

Calan

0 Aaron McIntosh 11 months ago in reply to Calan Elaya

Prodigy 90 points

Hello Calan,

Thanks for the solution. I just wanted to confirm if the converter can handle 15A 12V output as the webpage states this, however, from what I could see, the datasheet does not mention this. I also realized I could not input these parameters into Webench without receiving a duty cycle exceeds limit message, when the datasheet suggests it should be capable of this duty cycle and I would like to ask why this is the case.

Thank you.

0 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

Can I confirm, is your FSW 500khz?

Thanks,
Calan

0 Aaron McIntosh 11 months ago in reply to Calan Elaya

Prodigy 90 points

Hi Calan,

Yes, that is what I was intending, but neither 500kHz or 300kHz work on Webench so I just wanted to make sure this was possible.

Thank you.

+1 Calan Elaya 11 months ago in reply to Aaron McIntosh

TI__Genius 11545 points

Hi Aaron,

Webench is limited in terms of duty cycle, that's why you see an error for this in Webench. Referring to the datasheet, this ideally should work since the duty cycle meets the datasheet duty cycle threshold. Although in a real application, the only way to confirm that this is stable, is to check this on the bench. I can check to confirm if this works on the bench, but this will take some time to order the board and test. I can keep you updated on the status of testing this.

Thank you,

Calan

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TPS56121: Simulation Errors