TPS7A78: SCIN voltage calculation

Part Number:TPS7A78

Hi team,

On the datasheet of TPS7A78, section 7.3.7, I found that the Vscin=4*(Vldo+0.6V)-2.5V, so the Vscin should be around 20V.

But according to the block diagram, SCIN should be the output of half bridge/full bridge rectified voltage from AC input.

If I put a 220VAC/50Hz AC input voltage on AC PIN, what's the Vscin voltage?

Could you please help to provide some calculation for this?

Thanks a lot.

James