UCC28704: Reference Schematic for UCC28704+ AC Brown out

Hello Ian,

The UCC28704 has input under voltage lockout that will turn of the converter encase of brownout. This is sensed the primary to auxiliary turns ratio through the upper VS divider.  The setup of this circuit is discussed on page 10 section 7.3.1.3 of the data sheet.

Ivsl(run) = 220 uA

Regards,

Mike

Dear Sir,

We know add external resistors in Vs pin, but brown out design has problem.

It will depend on load change, that's why we ask if there are external circuit. 

Thanks, Ian.