Datasheet

®
INA114
11
FIGURE 8. RTD Temperature Measurement Circuit.
SEEBECK
ISA COEFFICIENT R
2
R
4
TYPE MATERIAL (µV/°C) (R
3
= 100Ω)(R
5
+ R
6
= 100Ω)
E Chromel 58.5 3.48kΩ 56.2kΩ
Constantan
J Iron 50.2 4.12kΩ 64.9kΩ
Constantan
K Chromel 39.4 5.23kΩ 80.6kΩ
Alumel
T Copper 38.0 5.49kΩ 84.5kΩ
Constantan
NOTES: (1) –2.1mV/°C at 200µA. (2) R
7
provides down-scale burn-out indication.
FIGURE 9. Thermocouple Amplifier With Cold Junction Compensation.
INA114
R
G
Ref
V
O
100µA
V+ V+
R
Z
RTD
1
2
3
Equal line resistance here creates
a small common-mode voltage
which is rejected by INA114.
Resistance in this line causes
a small common-mode voltage
which is re
j
ected b
y
INA114.
V
O
= 0V at R
RTD
= R
Z
REF200
REF102
R
80.6k
4
Ω
R
1M
7
Ω
R
5.23k
2
Ω
R
27k
1
Ω
R
100
3
Ω
1N4148
Cu
Cu
R
50
5
Ω
R
100
Zero Adj
6
Ω
V+
K
6
10.0V
4
(1)
(2)
2
INA114
V
O
Ref