Here's a TL431 cutoff circuit using a P-MOSFET with hysteresis:
R4 provides a small amount of positive feedback to generate about 200mV of hysteresis which should prevent the circuit from dithering at the trip point.
hi gk,
You most likely have no TL431 module, as the Error message shows.
Unzip this zip file.
Place the .lib in the LTSpice SUB folder and
the .asy in the LTSpice CMP folder,
restart LTSpice
Type .inc TL431.lib on the asc file circuit digram.