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120
Principles of Operation
6.3.1.3
Temperature Resolution
You must also consider measurement resolution since the resolution
decreases as the thermistor temperature increases. The microprocessor
converts this digital number to resistance, stores this resistance, then converts
it to a temperature using the Steinhart-Hart equation, and stores this
temperature. A temperature change of one degree centigrade will be
represented by a greater resistance increase (and therefore more ADC counts)
at lower temperatures because of the non-linear resistance of the thermistor.
Resolution figures for a typical 10 k thermistor are given below.
Temperature
-20 C
25 C
50 C
Figure 34
Thermistor Temperature Range
Voltage at 10 A
56.0 mV/C
4.4 mV/C
1.4 mV/C
Resolution
0.018 C/mV
0.230 C/mV
0.700 C/mV
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