TBX-68S Isothermal Terminal Block
6
ni.com
where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit
and degrees Celsius, respectively.
The thermistor resistance varies from 16,305
Ω
to 1,492
Ω
over a 0° to
55° C temperature range.
Note
V
TEMPOUT
varies from 198.54 mV (at 0° C) to 19.58 mV (at 55° C). For best
resolution, use the maximum gain for this signal range on the analog input channel of your
measurement device.
The 200 mV range is designed to eliminate the necessity of changing a measurement
device’s signal range to measure the cold-junction sensor while scanning thermocouples.
Use an average of a large number of samples to obtain the most accurate reading. Noisy
environments require more samples for greater accuracy.
Figure 3 shows the circuit diagram of the TBX-68S cold-junction
temperature sensor.
Figure 3.
Temperature Sensor Circuit Diagram
5 k
Ω
at 25˚ C
189 k
Ω
0.1%
LM 4040
2.5 V
0.1%
4.7 k
Ω
1%
2.5 V
10
μ
F
16 V
0.1
μ
F
0.1
μ
F
1
2
1
2
2
CJSense –
C
+5 V
+
–†˚
