2

6

10.0V

4

REF102

INA114

or

INA128

+In

7

4

3

8

1

2

5

16

15

8

10

ISO124

7

V

OUT

9

6

–In

+15V

+15V

–15V

+15V –15V

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

R

2

(R

3 = 100Ω)

3.48kΩ

4.12kΩ

5.23kΩ

5.49kΩ

R

4

(R

5 + R6 = 100Ω)

56.2kΩ

64.9kΩ

80.6kΩ

84.5kΩ

+15V –15V

R

3

100Ω

Ground Loop Through Conduit

NOTE: (1) –2.1mV/°C at 2.00µA.

R

1

27kΩ

Isothermal

Block with

1N4148(1)

R

2

1MΩ

R

5

50Ω

R

G

R

4

R

6

100

Zero Adj

Thermocouple

2

1

15

ISO124

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SBOS074E – SEPTEMBER 1997 – REVISED JUNE 2018

Product Folder Links: ISO124

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Copyright © 1997–2018, Texas Instruments Incorporated

Typical Applications (continued)

8.2.4 Thermocouple Amplifier

For isolated temperature measurements, Figure 19 provides an application solution using the INA114 or INA128

devices, feeding the input stage of the ISO124 device. The table provides suggested resistor values based on

the type of thermistor used in the application.

Figure 19. Thermocouple Amplifier With Ground Loop Elimination,

Cold Junction Compensation, and Up-scale Burn-out