ltspicetemperaturethermistor
I have a schematic for a temperature controlled device which should operate at a particular temperature.
For that I am using an NTC, now I have done the math by hand but it is more efficient and effective to include a diagram and an LTspice simulation, how could I model an NTC as the parameters such as "B-Curve" and ABC for the Steinhart and Hart equations are the only ones that change?
This particular P/N is not included in the library yet . It has the same characteristics as NTCLE101E3C90173 though. So if you are not concnerned about self heating, you can use this other P/N iso NTCLE413E2103F520L. If you open the library in LT spice you will see all the P/N included in this library. Not all the P/N are included
I'm posting the answer since it is instructive to see what can happen with the default timestep when the simulation spans too big an interval.
This is the circuit in LTSpice.
A minimum time step of 50us is more than adequate to give a stable solution on 200 ms interval:
But take it to 60us with .tran 0 200m 0 60u startup and you will see the solution drifting toward the time axis:
With 100us timestep we get shape similar - but only similar - to an exponential decay of the mean value
Best Answer
The way that I would do this to try different NTC's in a simulation would be to set a few parameters, I only did this for the regular beta equation and not for the full three parameter equation, but this shows you what is possible. (the three parameter equation would take a lot more time to set up)
Rtherm2 is set by parameters, you could set up A B C parameters and equations, it's also possible to set up interm equations (see b-sources section here)
Rtherm1 is the way I prefer to test circuits with NTC's you can set a range of resistance values by looking at a table ( a high and low value) and then run a simulation with the values ramping between high and low.