V+
V+
REF200
100µA
Equal line resistance here creates
a small common-mode voltage
which is rejected by INA114.
1
VO
RTD
RG
INA114
Ref
2
RZ
3
VO = 0V at RRTD = RZ
Resistance in this line causes
a small common-mode voltage
which is rejected by INA114.
FIGURE 8. RTD Temperature Measurement Circuit.
V+
2
10.0V
6
REF102
R1
R4
27kΩ
80.6kΩ
4
R(72)
1N4148
R2
(1)
1MΩ
5.23k
Ω
VO
Cu
Cu
INA114
Ref
K
R5
R3
50Ω
100Ω
R6
100Ω
Zero Adj
SEEBECK
ISA
COEFFICIENT
R2
R4
TYPE
MATERIAL
(µV/°C)
(R3 = 100Ω)
(R5 + R6 = 100Ω)
E
J
Chromel
Constantan
58.5
50.2
39.4
38.0
3.48kΩ
56.2kΩ
Iron
Constantan
4.12kΩ
5.23kΩ
5.49kΩ
64.9kΩ
80.6kΩ
84.5kΩ
K
T
Chromel
Alumel
Copper
Constantan
NOTES: (1) –2.1mV/°C at 200µA. (2) R7 provides down-scale burn-out indication.
FIGURE 9. Thermocouple Amplifier With Cold Junction Compensation.
®
11
INA114
TI [ TEXAS INSTRUMENTS ]
