Chapter 4
Theory of Operation
©
National Instruments Corporation
4-11
Figure 4-4.
Resistance-Temperature Curve for a 2,252
Ω
Thermistor
The thermistor has been used primarily for high-resolution measurements
over limited temperature ranges. However, continuing improvements in
thermistor stability, accuracy, and interchangeability have prompted
increased use of thermistors in a variety of applications.
Thermistor Measurement Circuits
This section details information about thermistor measurement circuits.
The most common technique is to use a current-source, and measure the
voltage developed across the thermistor. Figure shows the measured
voltage V
0
equals
R
T
×
I
EX
.
Figure 4-5.
Thermistor Measurement with Constant Current Excitation
,
+
–
V
0
V
0
= I
EX
x R
T
R
T
Thermistor
I
EX
