
TrendReader Standard 2
95
2005 ACR Systems Inc.
A thermistor equation, as the name implies, will create an equation for a thermistor
temperature sensor. The equation is in the form a Steinhart-Hart equation, which is generally
acknowledged as the best equation available for making the thermistor response curve linear.
The basic form of the equation is as follows:
1/T = A + B*(LnR) + C*(LnR)^3
T = temperature in degrees Kelvin (degrees Celsius + 273.15)
LnR = natural logarithm of the resistance of the thermistor (in ohms)
A, B, C = curve-fitting constants derived from measurement
Note that thermistor equations are created only for NTC (negative temperature coefficient)
If you want to enter in your own specific formula, and not have
an equation, select Empty Equation. This will create a shell for your equation. When the
wizard is completed, you will be taken to the editor window where you can enter in your
formula. For help on equation coding and examples, refer to
APPENDIX A Equation Language
7.2.4 Parameters
In the fourth step of the wizard, you enter the measurements you recorded or obtained from a
specification sheet to generate the equation. Note that this step is omitted if you selected an
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