Hi Kamalnish,
Could you fill out the TI quickstart calculator? I suspect there may be insufficient COUT.
https://www.ti.com/tool/LM2557X-557XQUICK-CALC
Thanks,
Andrew
Hi Shing,
You can download the circuit calculator for LM5576 application design.
http://www.ti.com/tool/lm2557x-557xquick-calc
You also can simulate the design in Webench, check power loss and IC thermal if meet your requirement, then export the PCB layout…