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Application — Thermistors The resistance of NTC thermistors decreases as the temperature increases. NTC thermistors are the most common type of thermistors in use. The resistance of PTC thermistors increases as the temperature increases. Thermistors are available with a variety of resistance values. The resistance of thermistors is commonly specified at a temperature of 25°C (77°F) for ease of testing before they are placed into a heating or cooling application. Although thermistors are available with a variety of resistance values, standard NTC thermistors rated at 25°C (77°F) include the following resistance values: 2 kΩ, 3 kΩ, 5 kΩ, 10 kΩ, 30 kΩ, 50 kΩ, and 1 MΩ. Changes in thermistor resistance are not linear with temperature changes. Manufacturers provide charts showing specific resistances at each temperature above and below the thermistor rating (typically 25°C). See Temperature vs. Resistance — 2000 Ω NTC Thermistor.

TEMPERATURE vs. RESISTANCE—2000 Ω NTC THERMISTOR Temperature °F –40.00 –22.00 –4.00 14.00 32.00 41.00 59.00 77.00 95.00 113.00 131.00 149.00 167.00 185.00 203.00 212.00

°C –40.00 –30.00 –20.00 –10.00 0.00 5.00 15.00 25.00 35.00 45.00 55.00 65.00 75.00 85.00 95.00 100.00

Resistance Nominal Ohm 67,021 35,305 19,338 11,058 6,530 5,079 3,143 2,000 1,306 873 597 416 296 214 157 136

Resistance Minimum Ohm

Maximum Ohm

Resistance Tolerance*

Temperature Tolerance†

64,412 34,230 18,944 10,880 6,464 5,029 3,114 1,983 1,295 867 593 414 293 211 154 133

69,747 36,418 19,843 11,240 6,597 5,130 3,172 2,018 1,317 880 601 419 299 218 161 139

4.07 3.15 2.35 1.65 1.03 1.00 0.94 0.88 0.83 0.79 0.74 0.70 1.00 1.59 2.12 2.37

0.60 0.50 0.40 0.30 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.30 0.50 0.70 0.80

* in ± % † in ± °C

© 2014 American Technical Publishers, Inc. All rights reserved

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