i am using LTC4366-2 in my design to clamp output at 235V. but it is clamping at 180V. what will be the possible reasons?

LTC4366
Recommended for New Designs
The LTC4366 surge stopper protects loads from high voltage transients. By controlling the gate of an external N-channel MOSFET, the LTC4366 regulates the...
Datasheet
LTC4366 on Analog.com
i am using LTC4366-2 in my design to clamp output at 235V. but it is clamping at 180V. what will be the possible reasons?

Hi Sangram22 ,
Kindly explain whether you are seeing that with your simulation model or on an actual build prototype.
1. If it is with the simulation model, please provide the LTspice file.
2. If it is with the actual physical proto, please provide the schematics and layout images.
Cheers, heke
It is with actual proto. can not provide schematic here.

I have few more observations; if i keep SD pin open above issue not observed upto 190V.
Few input to understand the design-
1) power supply input= 80 to 180Vac
2) Clamping set for 235Vdc- (rectified voltage)
It is with actual proto. can not provide schematic here.

I have few more observations; if i keep SD pin open above issue not observed upto 190V.
Few input to understand the design-
1) power supply input= 80 to 180Vac
2) Clamping set for 235Vdc- (rectified voltage)