54 Chapter 4 Temperature Controller Module Operation
In the 8000 the practical upper temperature limit is the temperature at which the
thermistor becomes insensitive to temperature changes. The lower end of the
temperature range is limited by the maximum A/D input voltage of the 8000.
Thermistor resistance and voltage are related through Ohm's Law (V = I x R). The
8000 supplies current to the thermistor, either 10 µA or 100 µA , and as the
resistance changes a changing voltage signal is available to the thermistor inputs of
the 8000. The 8000 will over-range when the input voltage exceeds about 5 Volts.
Figure 26 graphically shows the lower temperature and upper voltage limits for a
typical 10 k Ohm thermistor. The practical temperature ranges for a typical 10 K
thermistor (a 10 K thermistor has a resistance of 10 k Ohms at 25°C) are given in the
table below.
Sensing Current
Temperature Range
10 µA -51 to 40°C
100 µA -10 to 100°C
Figure 26 - Thermistor Temperature Range
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
