PMLKBUCKEVM: Vsw wavefrom issue

Part Number: PMLKBUCKEVM

Hi,

Currently i'm doing the experiment 1 test 1, Vin 24V, Vout 3.3V, Iout change from 0.1A to 1.5A.

i find when the Iout is lower than 0.7A, the Vsw will show some weird waveform. shown below.

Iout=0.1A

Iout=0.5A

In the Iout=0.1A image, i think maybe TPS54160 is in ECO-mode. But what cause the ringing in the red circle?

In the Iout=0.5A image, what cause the Vsw is high in the red circle? 

Thanks.

Best regards

Mason Liu