Figure A.1 Thermistor Resistance Vs. Temperature - ILX Lightwave Temperature Controller LDT-5525 User Manual

A
C H A P T E R
For the LDT-5525, the Steinhart Hart equation has been simplified to a first order
polynomial:
1/T = A' + B' * ln R
This equation is easier to solve and provides adequate results. Table A.1 also
shows that the use of Equation 2 introduces temperature errors of less than 0.3
over the range -20
temperature ranges near room temperature
1 Resistance of a 10 k
2 Constants A' = 0.99 * 10
Once the constants A' and B' are determined, the LDT 5525 Temperature
Controller is programmed with the following values of C1, and C2:
C1 = A' * 10
C2 = B' * 10
28
LDT-5525
Equation 2
o C to 50 o C, with accuracies of up to 0.06
W
, Dale 1T1002-5 thermistor
-3
, B' = 2.57 * 10
THERMISTOR R/T CURVES
FOR VARYING ROOM TEMP. RESISTANCES
50.00
40.00
30.00
k Ω
20.00
2.5 k 5 k
1 k
10.00
0.00
-40
-60 0
-20
TEMPERATURE (DEGREES C)

Figure A.1 Thermistor Resistance vs. Temperature

+3
+4
2
.
-4
(C1 = 0.99, C2 = 2.57).
10 k 25 k 50 k
100 k
80
60 100
20 40
o C over smaller
160
120 140
C
o