I was constructing the UC3843 on PSIM from scratch. The circuit diagram and the application note state that if the input voltage is greater than 34 V, the Zener diode does not allow the circuit to run. This is how it seems in the block diagram of the UC3843:
However, in my PSIM, the circuit still works normally when I design it like this:
This means that the output at that point is still VCC even if the VCC is >34 V. In that case, what's wrong here and how to modify this part so that the VCC >34 V will turn off the circuit just like the application note says?