LMZ31503 Simulation problem on Webench designer

Satoshi

Guru 19685 points

Other Parts Discussed in Thread: LMZ31503, TPS54320, TPS84320

LMZ31503 simulated below condition and not changed external circuit value.

⇒Vin: 4.8V~5.5V, Vout: 1V, Iout: 1A

When simulate the startup waveform, Vout was not reach 1V.

Please see below, Vout is 500nV_max by Y-axis.

Is this Webench's bug, correct?

If bug is not, please let me know the measure to normal Vout startup.

My Webench design is shared below;

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=B0BCD87626403781

Best regards,

Satoshi

over 4 years ago

0 Nancy Zhang over 4 years ago

TI__Mastermind 49470 points

Hi Satoshi,

Yes, you are right. I could not run simulation either. Will report this issue to Webench team and get you back soon.

Thanks,

Nancy

0 Satoshi over 4 years ago in reply to Nancy Zhang

Guru 19685 points

Hi Nancy

Thank you for confirming and reply,

Please let me know if there prospect schedule for bug fix.

Just in case, please let me confirm about Bode Plot simulation occur bug or normal.

(Bode Plot look like normal, but I didn't judge. Load Transient and Input Transient are occur bug, too.)

Best regards,

Satoshi

0 Nancy Zhang over 4 years ago in reply to Satoshi

TI__Mastermind 49470 points

Hi Satoshi,

I already submit the ticket to Webench team and will push them again. For bode plot and transient, I don't trust the simulation results and ask them to double check as well. Thanks for your patience!

Thanks,

Nancy

0 Satoshi over 4 years ago in reply to Nancy Zhang

Guru 19685 points

Hi Nancy,

Thank you for following,

I looking forward Webench update.

One customer want to confirm bode plot (Phase margin) simulation, and looking for the other way to simulation tool during Webench bug fix.

Additional question, Please let me know about internal compensation circuit and resister and capacitor value for LMZ31503, because I trying to confirm TPS54320 Webench simulation.

Or, is there the other recommend tool for bode plot simulation? (For example, power stage designer, PSPICE for TI, etc)

Best regards,

Satoshi

+1 Nancy Zhang over 4 years ago in reply to Satoshi

TI__Mastermind 49470 points

Hi Satoshi,

1. I could not confirm if the bode plot simulation is correct or not because I am not sure if Coutx is connected or not in the Webench schematic. From the crossover frequency, it should be connected. I contact webench team again and should get their feedback tomorrow.

2. You can not use TPS54320 Webench simulation since the loop compensation may be different. LMZ31503 used TPS84320 inside. But there is no Webench for TPS84320.

3. You can use PSPICE to run start up and static state in LMZ31503 folder. No tool for bode plot and let's wait for tomorrow.

Thanks,

Nancy

+1 Nancy Zhang over 4 years ago in reply to Nancy Zhang

TI__Mastermind 49470 points

Hi Satoshi,

The bode plot simulation is pretty accurate. But you need to change Coutx=1uF since it is actually connected. Please review my slide as attached. So you can use Webench for bode plot and Pspice for start up and static state now.

LMZ31503 Bode plot simulation.pptx

Thanks,

Nancy

0 Praveen Badiger over 4 years ago in reply to Nancy Zhang

TI__Expert 8365 points

Hi Satoshi,

We have started working on the simulation issue. We will inform you once the issue is fixed.

Thanks & Regards,
Praveen

0 Satoshi over 4 years ago in reply to Praveen Badiger

Guru 19685 points

Hi Nancy, Praveen,

Thank you for support and information.

I understand the situation.

Best regards,

Satoshi

0 Shuai Fan over 4 years ago in reply to Satoshi

TI__Genius 13451 points

Hi Satoshi!

Thanks for your feedback!

Shuai

+1 Nancy Zhang over 4 years ago in reply to Shuai Fan

TI__Mastermind 49470 points

Hi Satoshi,

Praveen fixed this issue. The fix will be available on web in next release cycle by end of next week.

Thanks for your patience!

Nancy

+1 Praveen Badiger over 4 years ago in reply to Nancy Zhang

TI__Expert 8365 points

Hi Satoshi,

The fix is available on ti.com.

Thanks & Regards,
Praveen

0 Satoshi over 4 years ago in reply to Praveen Badiger

Guru 19685 points

Hi Praveen, Nancy,

Now I confirmed LMZ31503 Webench simulation and fixed.

I appreciate your kind support.

Best regards,

Satoshi

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LMZ31503 Simulation problem on Webench designer