LM25148-Q1: WEBENCH warning "Design update failed - This design is not stable due to phase margin either smaller than 35 or greater than 120." when current step is changed

Isao Takigasaki

Part Number: LM25148-Q1
Other Parts Discussed in Thread: LM25149

Hi,

I run the WEBENCH on LM25148-Q1 with changing the value of transient response current step from 5A to 1A as shown in below.

Then, the following warning message appeared.

I checked the phase margin result, but the result was not changed.
I think 1A of current step is out of range to calculate in this case or something happened. Is my understanding correct?
Or is there anything I can do to solve it?

The link of this Webench setting can be seen from the following link. PLS refer it.

webench.ti.com/.../SDP.cgi

The another question is why the current step setting affect phase margin?

Best Regards, Taki

10 months ago

0 Marshall_Beck 10 months ago

TI__Mastermind 35190 points

Hi Taki-san,

That doesn't make sense to me either. This shouldn't impact the stability.

Could you share me the link the design by using the insert link function?

Your post had its link incorrectly posted. I would like to report this to the webench team.

Also, to help with your design we have an excel calculator tool on the product folder in design tools section. That could be useful for you to examine the stability.