LM5164: High ripple output voltage

Part Number: LM5164

Hello,

I am using your LM5164 regulator to step down from 41V to 5V. I used Webench to design this regulator. I expected a output ripple votage of 30mV at no load (see webench report) but I get 1V with a frequency of 8kHz : the regulator is producing an audible noise. With a load of 370mA the ripple is lower but still higher than expected.

I attached a picture of my PCB, the Webench Design schematics and Voutp-p, and oscilloscope's screenshots of Vout et Vsw with and without load.

- Do you understand why the ripple voltage is so high compare to Webench?
- How to improve the regulation?

Thanks for your help.