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AX3500 Motor Controller User’s Manual 65
Connecting External Thermistor to Analog Inputs
Connecting External Thermistor to Analog Inputs
Using external thermistors, the AX3500 can be made to supervise the motor’s tempera-
ture and adjust the power output in case of overheating. Connecting thermistors is done
according to the diagram show in Figure 34. The AX3500 is calibrated using a 10kOhm
Negative Coefficient Thermistor (NTC) with the temperature/resistance characteristics
shown in the table below.
Thermistors are non-linear devices. Using the circuit described on Figure 34, the controller
will read the following values (represented in signed binary) according to the temperature.
TABLE 13. 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 34. NTC Thermistor wiring diagram