TPS92520-Q1: How to test the loop about the TPS92520

Hello Zhiyaun,

There is no need to perform a gain phase testing for this design.  It is a single pole system that is inherently is stable.  The control loop controls the current directly out of the inductor so it isn't affected by the output capacitance, thus the single pole system.  The COMP capacitor sets the cross over frequency, thus the bandwidth of the feedback loop.  This is covered in the datasheet.    

These results were done in simulations.  Trying to inject a measurable signal into the feedback loop is difficult because the it is a differential signal across a really small current sense resistor.  

-Francis Houde

Here is a E2E post that addresses the potential setup of this testing, but I have not myself done this testing because it is a single pole system and is inherently stable.  

https://e2e.ti.com/support/power-management-group/power-management---internal/f/power-management---internal-forum/1235863/tps92520-q1-measurement-about-loop-gain 

Here is the high level diagram of the potential setup.  

I have not done this test setup because we understand that this control loop is inherently stable and is a single pole system.  We did simulations to verify this which can be done with the Simplis mode in the TPS92520-Q1 main page.  If you want to verify this using this test setup then by all means go ahead, but this is not an easy setup and in my opinion not worth the effort and time to perform this test.  

-fhoude