UCC28780EVM-002: UCC28780 EVM Switching waveform stairs to occur Question.

Part Number:UCC28780EVM-002

Dear support member,

I used UCC28780.
I have a question about switching waveform.

（Specification condition）
Vin：250Vac
Vout：12Vdc
Iout：2A

（Situation)
The switching waveform was measured by UCC28780 EVM-002.
The switching waveform is stepped.

（Question)
What causes the stairs to occur?
Could you teach reason?

I attached the waveform.
Could you check it?

(Please visit the site to view this file)

Best regard.
Bob Lee.