UCC28780: Question about the PWMH of UCC28780

Part Number:UCC28780

Hello

I have a question about the PWMH of UCC28780.

The PWMH will go high when the PWML goes down (turning off the low side MOSFET)

Then, when the PWMH goes down to turn the high-side MOSFET off?  Could you explain detail mechanism?