ISO122_15 Datasheet, PDF (14/26 Pages) Texas Instruments – Precision Lowest-Cost Isolation Amplifier

ISO122
SBOS160A – NOVEMBER 1993 – REVISED JANUARY 2015
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Typical Application (continued)
9.2.4 Thermocouple Amplifier
For isolated temperature measurements, Figure 19 provides an application solution using the INA101 feeding the
input stage of the ISO122. The table provides suggested resistor values based on the type of thermistor used in
the application.
+15V
10.0V 6
Thermocouple
R₄
R₁
27kW
2
REF ⁴
102
+15V
+15V –15V +15V –15V
Isothermal
Block with
1N4148 ⁽¹⁾
1MW
R
2
R₃
100W
12
4
5
R_G
10
11
3
2
+In
INA101
–In
13
R₅
50W
–15V
R
6
100
Zero Adj
Ground Loop Through Conduit
NOTE: (1) –2.1mV/°C at 2.00µA.
1
14
1
2
15
16
ISO122P
9
10 7 V
OUT
8
ISA
TYPE
E
J
K
T
MATERIAL
Chromel
Constantan
Iron
Constantan
Chromel
Alumel
Copper
Constantan
SEEBACK
COEFFICIENT
(µV/°C)
58.5
50.2
39.4
38.0
R₂
(R₃ = 100W)
3.48kW
4.12kW
5.23kW
5.49kW
R₄
(R₅ + R₆ = 100W)
56.2kW
64.9kW
80.6kW
84.5kW
Figure 19. Thermocouple Amplifier With Ground Loop Elimination,
Cold Junction Compensation, and Up-scale Burn-out.
14
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