Loop response of a buck converter

[manishanand14]

Hi Everyone!

What is significance of loop response of a Buck Converter.



I have attached the design of Buck Converter using TPS54331.

 

[FvM]

I don't believe that the phase response is correct. It's impossible to achieve. A physical plausible phase response is e.g. shown in Figure 22 of the TPS54331 datasheet.

In contrast to the plotted response, there will be an additional phase lag caused by the average PWM modulator delay.

 

[mtwieg]

Yes that phase response doesn't make sense at all, for any part of the loop. The gain response looks somewhat plausible, but only for a severely damped system. I think the whole chart must be junk.

 

[manishanand14]

It has been produced using web-bench designer.

Anyway please tell me what is the use of loop response in case of buck converter in general.

 

[mtwieg]

Well the tool has some problems with it. None of the pole/zero locations in the circuit match up with the plot.

Anyways the loop response can tell you about the stability of the feedback loop, and what kind of transient response the circuit will have to load or line disturbances.