TPS54040A: PSPICE simulation

Alfred Logico

Part Number: TPS54040A

Hi Team,

I regards to the TPS54040A, my customer have noticed some odd behavior when simulating the part. I have attached a screenshot of the output voltage from the PSPICE transient simulation available on your website (https://www.ti.com/lit/zip/slim069) of the output voltage after 5ms, we haven't changed anything in the simulation schematic that's available online except for increasing the simulation time. I would have expected that the voltage will have reached steady state after 5ms and the output voltage waveform would be relatively constant with just the filtered switching ripple superimposed. The simulation is showing a lower frequency oscillation, perhaps this is noise, we have some concern about this and are wondering if someone in your team could explain why we would be seeing this?

Thanks!

BR,
Alfred

over 4 years ago

0 iAlejandro over 4 years ago

TI__Expert 8130 points

Hi Alfred,

It might be a simulation artifact. Can you provide an image of where exactly the customer is probing in the schematic?
I tried to replicate this phenomena but I did not see this noise on my results.

Thanks,
Alejandro

0 Alfred Logico over 4 years ago in reply to iAlejandro

TI__Expert 5060 points

Hi Alejandro,

Please see below screenshot where the customer is probing as well as the simulation settings. Is there a certain setting for the PSPICE solver that you would recommend – they are using the default integration method currently, perhaps this is the issue?

0 iAlejandro over 4 years ago in reply to Alfred Logico

TI__Expert 8130 points

Alfred,

I'm not sure what you mean by "default integration method"? I ran it on my end with identical settings and do not get the same results as the customer.

Regards,
Alejandro

0 Alfred Logico over 4 years ago in reply to iAlejandro

TI__Expert 5060 points

Hi Alejandro,

I think what they meant is that this is using the default settings. Can you share with me the outcome of your test results? I tried on my end with the same settings as customer for the transient simulation and I got the below result which is similar to customers.

Thanks!

BR,

Alfred

0 Alfred Logico over 4 years ago in reply to iAlejandro

TI__Expert 5060 points

Hi Alejandro,

Thanks!

BR,

Alfred

0 iAlejandro over 4 years ago in reply to Alfred Logico

TI__Expert 8130 points

Alfred,

Apologies on my mistake, my first simulation had incorrect x-axis intervals, which resulted the following:

After the proper input on the x-intervals, I did get the phenomena:

I'm not exactly sure what is causing this. As you stated, it can be a result of unwanted noise. Let me reach out to the team internally and provide you with further info.

Thanks,
Alejandro

0 Alfred Logico over 4 years ago in reply to iAlejandro

TI__Expert 5060 points

Hi Alejandro,

Good day!
Any feedback on this?

Thanks!

Best Regards,

Alfred

0 iAlejandro over 4 years ago in reply to Alfred Logico

TI__Expert 8130 points

Hi Alfred,

I looked into the simulation more and we don't have a definite conclusion to this matter. Changing the convergence parameteres, time step, etc. did not improve.This noise is most likely due to an artifact of the simulation. Plus, the noise seen is less than 1mV.

Also, WEBENCH is simulating and indicating a stable design.

Regards,
Alejandro

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TPS54040A: PSPICE simulation