hi gk,
Don't give up on your LTSpice studies, you will find useful in the future.
E

 

Do I remember incorrectly that @crutschow recently had at least one undervoltage circuit with a P-MOS transistor?

 

Note: When using an LM431 the 3.3k resistors may be replaced by 6.8k resistors.

 

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.

 

Thank you so much guys!

This is super helpful.

 

So im determined to make this circuit.

Can i get some help with this error?

 

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.


E

 

For one thing, the gate of the MOSFET needs to be connected to the cathode of the TM431 and its anode grounded.

 

For another thing, right-click the MOSFET symbol and select a suitable MOSFET instead of the default one (which rarely works well).

 

Why did you change the working circuit I posted to one that doesn't?