Under voltage protection circuit - HV side

[Zegdus]

Hi!
Can anyone please help in designing under voltage protection circuit with will protect SMPS against power line voltage drop under 40V (KAM0705 module - ( U1 )- https://www.alldatasheet.com/datasheet-pdf/pdf/265967/CHINFA/KAM0705.html). Is this circuit correct? Power supply voltage U= 110V/AC. Important - i can't use conventional transformer in my design.

 

[alec_t]

Can't tell whether your circuit is correct as we don't know all of its intended functions.
Regarding the 40V (I assume you mean 40V rms) cut-off, you could perhaps use a resistor divider network plus zener across the bridge rectifier to sense if the rectifier output is above 40* root 2, then control a power mosfet accordingly to apply power to the SMPS.