ATP Resistance vs. Temperature Conversion Table Coated Chip NTC Thermistor
This R/T Conversion Table is provided for reference only. ATP uses the Steinhart-Hart equation to calculate the
nominal Rt/R25 value. 1
°
C tables are available upon request.
Advanced Thermal Products, Inc. • P.O. Box 249 • 328 Ridgway Road • St. Marys, PA 15857 • Phone: 814-834-1541
Fax: 814-834-1556 • E-mail: sales@atpsensor.com • Web Site: www.atpsensor.com
•Rt/R25 - The ratio of the thermistor resistance at any temperature
divided by its' resistance at 25°C. For example, if you select a
10kΩ at 25°C thermistor in Material "Z", you can calculate its'
nominal resistance at 100°C to be 10,000 x .06787 = 678.7Ω.
•α - Negative Temperature Coefficient of Resistance expressed
in %/°C. This is the percentage change in thermistor resistance
for a 1°C change in its body temperature. α is particularly useful
in calculating the required resistance tolerance necessary to
guarantee sensor accuracy. For example, a Material "C"
thermistor has an α of -3.5%/°C at 50°C. If you require a
sensor that is accurate to within + 2.0°C at 50°C, the thermistor
must have a resistance tolerance of + 2.0°C x 3.5%/°C= + 7.0%.
•Curve Dev. — Applies to thermistors that are point matched at
25°C. The Curve Dev. (%) must be added to the thermistor
tolerance at 25°C to calculate the total tolerance or maximum
deviation at any temperature. Curve Dev. accounts for the curve
variance that occurs within any given batch or lot of thermistors.
For example, if you specify a Material "Z" device with a + 5%
tolerance at 25°C, it will have a total tolerance at 80°C of (+ 5%)
+(±2.3%)= ±7.3%.
47
Material K C Z D H
Temp. Coef.
@25˚C(α
25
)-3.9%/˚C -4.0%/˚C -4.4%/˚C -4.7%/˚C -5.3%/˚C
Resistance Ratio
R
0
/R
50
7.04 7.58 9.06 10.45 14.09
Beta
(β
25/85
) 3498 3694 3976 4262 4851
Temperature
(˚F) (˚C) R
t
R
25
α
(%/˚C)
Curve
Dev. R
t
R
25
α
(%/˚C)
Curve
Dev. R
t
R
25
α
(%/˚C)
Curve
Dev. R
t
R
25
α
(%/˚C)
Curve
Dev. R
t
R
25
α
(%/˚C)
Curve
Dev.
-58 -50 39.46 6.2 8.2 44.20 6.3 4.3 66.75 7.1 5.5 83.47 7.4 7.0 110.1 7.4 17.4
-40 -40 21.68 5.8 6.8 23.99 5.9 3.6 33.56 6.6 4.3 40.70 6.9 5.1 55.50 7.2 15.6
-22 -30 12.38 5.4 5.6 13.53 5.6 2.9 17.67 6.2 3.5 20.78 6.5 4.1 28.40 7.0 14.6
-4 -20 7.329 5.1 4.4 7.894 5.2 2.3 9.697 5.8 2.7 11.07 6.1 3.2 14.65 6.8 13.7
14 -10 4.482 4.8 3.3 4.755 4.9 1.7 5.530 5.4 2.0 6.124 5.7 2.4 7.609 6.4 11.7
32 0 2.825 4.5 2.3 2.949 4.6 1.2 3.265 5.1 1.4 3.510 5.4 1.6 4.094 6.0 9.9
50 10 1.830 4.2 1.2 1.879 4.4 0.7 1.990 4.8 0.8 2.078 5.1 1.0 2.277 5.7 8.2
68 20 1.216 4.0 0.3 1.227 4.1 0.2 1.249 4.5 0.3 1.267 4.8 0.3 1.306 5.4 6.6
77 25 1.000 3.9 0.0 1.000 4.0 0.0 1.000 4.4 0.0 1.000 4.7 0.0 1.000 5.3 5.9
86 30 0.8270 3.7 0.6 0.8196 3.9 0.2 0.8056 4.3 0.3 0.7943 4.5 0.3 0.7709 5.1 5.2
104 40 0.5747 3.5 1.4 0.5594 3.7 0.6 0.5325 4.0 0.7 0.5106 4.3 0.9 0.4674 4.9 3.7
122 50 0.4074 3.3 2.2 0.3893 3.5 1.0 0.3601 3.8 1.2 0.3360 4.1 1.4 0.2905 4.6 2.4
140 60 0.2942 3.2 3.0 0.2760 3.4 1.3 0.2487 3.6 1.6 0.2259 3.9 1.9 0.1848 4.4 1.1
158 70 0.2161 3.0 3.6 0.1990 3.2 1.7 0.1752 3.4 2.0 0.1550 3.7 2.3 0.1202 4.2 0.0
176 80 0.1612 2.9 4.3 0.1458 3.0 2.0 0.1256 3.2 2.3 0.1084 3.5 2.7 0.07980 4.0 1.0
185 85 0.1401 2.8 4.6 0.1255 3.0 2.2 0.1071 3.2 2.5 0.09121 3.4 2.9 0.06550 3.9 1.5
194 90 0.1221 2.7 4.9 0.1084 2.9 2.3 0.09162 3.1 2.7 0.07710 3.3 3.1 0.05400 3.8 2.1
212 100 0.09376 2.6 5.5 0.08169 2.8 2.5 0.06787 2.9 3.0 0.05574 3.2 3.5 0.03720 3.6 3.1
230 110 0.07292 2.5 6.1 0.06238 2.6 2.8 0.05102 2.8 3.3 0.04092 3.0 3.9 0.02618 3.5 4.0
248 120 0.05738 2.3 6.7 0.04822 2.5 3.0 0.03887 2.7 3.6 0.03047 2.9 4.2 0.01860 3.3 4.9
257 125 0.05112 2.3 6.9 0.04258 2.5 3.1 0.03409 2.6 3.8 0.02642 2.8 4.5 0.01580 3.2 5.3
266 130 0.03770 2.4 3.3 0.02999 2.5 3.9 0.02299 2.8 4.8 0.01340 3.2 5.8
284 140 0.02979 2.3 3.5 0.02342 2.4 4.1 0.01756 2.6 5.4 0.00980 3.1 6.6
302 150 0.02377 2.2 3.7 0.01849 2.3 4.4 0.01357 2.5 6.1 0.00730 2.9 7.3