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AX500 Motor Controller User’s Manual 57
Connecting External Thermistor to Analog Inputs
Connecting External Thermistor to Analog Inputs
Using external thermistors, the AX500 can be made to supervise the motor’s temperature
and adjust the power output in case of overheating. Connecting thermistors is done
according to the diagram show in Figure 30. The AX500 is calibrated using a 10kOhm Neg-
ative Coefficient Thermistor (NTC) with the temperature/resistance characteristics shown
in the table below.
Thermistors are non-linear devices. Using the circuit described on Figure 30, the controller
will read the following values (represented in signed binary) according to the temperature.
TABLE 11. Recommended NTC characteristics
Temp (oC) -25 0 25 50 75 100
Resistance (kOhm) 86.39 27.28 10.00 4.16 1.92 0.93
47kOhm
10kOhm
47kOhm
10kOhm
10kOhm
NTC
Thermistor
Internal Resistors
and Converter
+5V 14
Ground 5
A/D
Ana 1: 11
Ana 2: 10
Ana 3: 12
Ana 4: 8
FIGURE 30. NTC Thermistor wiring diagram