TPS65023-Q1: minimum input voltage to maintain 3.3Vout Buck regulation

Tool/software:

Hi PMIC team, 

I usually look for a minimum OFF time of the high side FET, but I don't see this in the datasheet. 

What is the process to calculate the minimum allowed input voltage to maintain 3.3Vout regulation - for each of the Buck converters?

Thanks for any comments,

Stephanie