Do you have a thermistor model for LT SPICE? Possible parameters would be the 25 DEG C resistance and the B 25 / 50 parameter so the resistance changes correctly when running .temp T1 T2 simulations?
I show one method using a stepped TEMP.
The default of TEMP is 27°C if not specified. Be aware that TEMP is used by every component in your schematic - especially diodes and transistors change their behavior. You can avoid this, if you use another name e. g. TEMP1.
Replace the value of the resistsor with this equation enclosed by curly braces.
.step TEMP 0 50 1
Thank you, this is exactly what I need. I'm temperature compensating a BJT B-E junction so I want the TEMP command to also control the transistor models. I think ADI should make this a component with a menu to enter R at 25 deg and B 25 / 50 for people like me who are not familiar with traditional command line SPICE.
Vishay and Infineon provides subcircuit models for their NTC-thermistors. These subcircuits also include the self heating of the NTC-resistors.
Again thank you. One quick question, in the method that you described above, is the B value the B 25 / 50 value? Some NTC thermistors list a few B values, B 25 / 50, B 25 / 85 etc.
Also, the voltage across my thermistor will be less than one diode drop so I'm not concerned with self heating.
B25/50 menas you will get the best fit when you have this temperature range from 25°C to 50°C in your application. It may be still good for 0°C to 75°C.
B25/85 is better when you have a wider temperatur range from 25 to 85°C or beyond. Maybe from 0 to 100°C.
You will get more temperature measurement error beyond these limits.
Some manufcaturers provide the coefficients for another formula with more coefficients e. g. for the Steinhart-Hart formula. These formulas are very precise for a very large range of temperature.