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LTspice simulation of component with different shutdown/startup voltages

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I have a device that I'd like to model in LTspice for some power analysis, it consumes 24W constant at voltages above 12.5V, and below 12.5V it shuts down. I was able to model this simply with a voltage depend current source and a table of values. However, after it shuts down it doesn't start back up again until 13.5V.

Any ideas for creating a circuit that will have these characteristics?
 

Sounds like you want to add a comparator with hysteresis to your model. Some kind of positive feedback is required for it. LTSpice behavioral simulation has effectively unlimited capabilities to achieve things like this.
 

FvM said:
Sounds like you want to add a comparator with hysteresis to your model. Some kind of positive feedback is required for it. LTSpice behavioral simulation has effectively unlimited capabilities to achieve things like this.
Click to expand...

Thanks! That was what I was looking for, I implemented a comparator circuit with hysteresis but now I'm having another problem. It works with an ideal power supply hooked up to it, but if I add a series resistor between the voltage supply and the circuit thats consuming the load, the simulation hangs indefinitely. Any ideas?

Code: 
.subckt MOT 1 2 
*comparator
V2 N001 2 20
R1 N002 N001 4.7k
R2 2 N002 9.1k
R3 Vout N002 56k
XU2 N002 1 N001 2 Vout LT1017

*constant power load
B1 1 2 I=if(V(vout)<10,{PWR}/V(1),0.01)
.lib LTC1.lib
.ends MOT
 

Doesn't the "constant power" load consume infinite current at V = 0?
 

Yes it would, but I never experienced V=0 in my simulation, but I added a condition fixing that.

From my simulation it seems to get hung up when the arbritrary current source starts increasing current draw, which in turn changes the input voltage, which causes the V(Vout) of the comparator to drop, and thus the current to also drop. So it kind of gets stuck in a loop there.
 

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