TPS65265: Step Load Ripple

Shay Mor

Part Number: TPS65265

Hi,

I'm using TPS65265 power supply in my project and I have a problem with the ripple of the step load of 1.5A at VOUT2.

In my circuit I'm using the typical application parameter VOUT=1.5V, L=[4.7uF, 5.1A, 44.1mOhm DCR], Total capacity= 220uF (X7R), Loop Compensation Rc=6.8K, Cc=2.7nF, Cb=22pF. attached photo:

Before I planed the circuit I used the WebBench simulator but now the TPS65265 is not appear in the Webbench or PSpice.

Do you please make for me a simulation for kill the step load ripple as you can with change the Loop Compensation Rc, Cc, Cb parameter?

I can't adding more output capacitors and the value of the inductor seems ok.

attached photos of the step load ripple:

current ripple:

over 3 years ago

0 Zhao Ma over 3 years ago

TI__Genius 15135 points

Hi, Shay

Confirm with you: Load step from 1.5A --> 0A, right?

Suggestion for improving load transient performance:

1. Suggest changing L2 to 2.2uH.

2. Enlarging R34 from 6.8kohm to 20kohm.

Then test again.

0 Shay Mor over 2 years ago in reply to Zhao Ma

Intellectual 870 points

Thank you Zhao Ma,

I checked again and the total capacity of my circuit is 600uF instead of 200uF.

The replacement of Rc=R34 to 6.8K is very helpful:

- But after I understood that the circuit capacity was wrong I calculated the Rc= R34 again and replaced the 6.8K to 110K according to (19) formula in the datasheet at RC=110K the Fc= 50K