WEBENCH® Tools/TPS544B25: Unable to find crossover frequency from Bode plot

srikanth pillalamarri7

Part Number: TPS544B25
Other Parts Discussed in Thread: TPS544C25

Tool/software: WEBENCH® Design Tools

I want to use TPS544B25RVFR part in one of our internal applications. As to get familiar with the part we started running simulations using TI Webench power designer. Our requirement is to generate 1V @ 15A current from 12V input. With this specification when we ran AC analysis a Bode plot showing unrelated magnitude and Phase curves (Magnitude curve not crossing 0dB) through which we couldn't find crossover frequency, Gain margin etc.
Surprisingly, this is not the case with TPS544C25RVFR which has given some expected data.
Here, i am attaching Bode plot with both cases, can yo u please help us to get a better picture over them?

over 4 years ago

0 Gerold Dhanabalan - Online Design Tools over 4 years ago

TI__Genius 14455 points

Hi Srikanth,

While we are working on finding the root cause with the simulation issue, you can look at the charts section in the tool and you can get the cross over and phase margin for the design.

Regards,

Gerold

0 Amod Vaze over 4 years ago

TI__Mastermind 21755 points

Hi Srikanth,

Thanks for reporting this. I am able to reproduce the bode plot issue with TPS544B25. We will look into this and will keep you updated.

Regards,

Amod

0 Atul_Kulkarni over 4 years ago in reply to Amod Vaze

Genius 4910 points

Hi Srikanth,

There was a netlist issue due to which we were observing discrepancy. Currently, we have fixed it and this will be reflected on the TI site in our next production release. We will notify once it is up.

Regards,

Atul

0 srikanth pillalamarri7 over 4 years ago in reply to Atul_Kulkarni

Prodigy 130 points

Hi Atul/Amod/Gerold,

Thanks for the acknowledgment. If issue persists with netlist, can we use TPS544C25 for our simulations? Does there any significant difference (apart from load current rating) between TPS544B25 & TPS544C25?

We want to analyze TPS544B25 behavior by running simulations since multiple instances of TPS544B25 have been used in our application.

Regards

Srikanth

0 Atul_Kulkarni over 4 years ago in reply to srikanth pillalamarri7

Genius 4910 points

Hi Srikanth,

Yes, you can use TPS544C25 instead of TPS544B25 for your application as there are no significant changes between the two except load current rating.

Regards,

Atul

0 srikanth pillalamarri7 over 4 years ago in reply to Atul_Kulkarni

Prodigy 130 points

Thanks Atul for the info. Assuming issue is only with simulation for TPS544B25, functional and stability performance is good and reliable.

Can you please confirm it since we are using this part (TPS544B25)?

Regards

Srikanth

0 Atul_Kulkarni over 4 years ago in reply to srikanth pillalamarri7

Genius 4910 points

Hi Srikanth,

The issue was Webench was unable to calculate Rload for TPS544B25 device due to which there was a discrepancy in a crossover. We have fixed this now. Rload is being calculated properly for TPS544C25. Rest of the model is the same for both the devices.