TPS549D22: Low phase margin despite DCAP3 control

Hello Abhishek, 

The first step is to make sure the inductor and output caps are sized according to the spec of your applications. 

Below is an application note on DCAP3 

https://www.ti.com/lit/an/slvaf11/slvaf11.pdf?ts=1690395952753&ref_url=https%253A%252F%252Fwww.google.com%252F

Thanks!

Tahar 

Hi Tahar,

Could you please tell me if there's any facility to tweak values in the TI fusion PMBUS programming file that can help to improve Phase margin?

Hello Abhishek, 

Unfortunately, no, there is not internal setting that can be used to directly improve this. The device  supports both DCAP3 and DCAP operation that can be set. I think for your application DCAP3 is best fit  due to its simple to use and no external compensation features.

Did you run and transient with 30deg phase? How the ripple looks like? what it the bandwidth gain margin?  

Thanks! 

Tahar

Is there any way to improve phase margin using external component changes in the schematic? Our company's DVT guidelines require at least 50deg phase margin, hence we try to meet that if possible irrespective of step load transient response.

Hello Abhishek, 

As I mentioned in the previous post, please follow this application note. 

https://www.ti.com/lit/an/slvaf11/slvaf11.pdf?ts=1690395952753&ref_url=https%253A%252F%252Fwww.google.com%252F

Thanks 

Tahar