Thermistor Equation - Keithley 2750 User Manual

F-6 Temperature Equations
Table F-8
Type T inverse function polynomial
c =
0
c =
1
c =
2
c =
3
c =
4
c =
5
c =
6
c =
7
Error:
t = c
90
where: t

Thermistor equation

Temperature (in Kelvin) is calculated using the Steinhart-Hart equation as follows:
T =
K
where: T
Table F-9
Model 2750 curve fitting constants for thermistors
Constant
A
B
C
-200°C to 0°C
(-5,603µV to 0µV)
0.0
2.594 919 2 × 10 -2
-2.131 696 7 × 10 -7
7.901 869 2 × 10 -10
4.252 777 7 × 10 -13
1.330 447 3 × 10 -16
2.024 144 6 × 10 -20
1.266 817 1 × 10 -24
0.04°C to -0.02°C
2 3
+ c E + c E + c E
0 1 2 3
is the calculated temperature in °C.
90
E is the measured voltage in microvolts.
1
-----------------------------------------------------------
3
( ) [ ( ) ]
A + BlnR + C lnR
is the calculated temperature in Kelvin.
K
lnR is the natural log of the measured resistance of the thermistor.
A, B, and C are the curve fitting constants. The constants for the three thermistor
types used by the Model 2750 are listed in
2252Ω at 25°C
(Series 44004)
0.0014733
0.0002372
1.074e-7
Model 2750 Multimeter/Switch System User's Manual
0°C to 400°C
(0µV to 20,872µV)
0.0
2.592 800 × 10
-7.602 961 × 10
4.637 791 × 10
-2.165 394 × 10
6.048 144 × 10
-7.293 422 × 10
0.03°C to -0.03°C
i
... c E
i
Table
5000Ω at 25°C 10kΩ at 25°C
(Series 44007) (Series 44006)
0.001288 0.0010295
0.0002356 0.0002391
9.557e-8 1.568e-7
-2
-7
-11
-15
-20
-25
F-9.