Datasheet

ISO124
9
SBOS074C
www.ti.com
FIGURE 6. Thermocouple Amplifier with Ground Loop Elimination, Cold Junction Compensation, and Up-scale Burn-out.
FIGURE 7. Isolated 4-20mA Instrument Loop. (RTD shown.)
R
CM
1kΩ
RCV420
XTR105
R
G
R
Z
(1)
13
3
4
2
6
7
10
14
1
0.01µF
4-20mA
RTD
(PT100)
0.8mA 0.8mA
1.6mA
14
15
16
3
2
10
4
12
11
5, 13
15
16
2
1
Gnd
–V
S
= –15V
on PWS740
+V
S
= 15V on PWS740
9
10
7
8
–V
+V
ISO124
V
OUT
0V - 5V
NOTE: (1) R
Z
= RTD resistance at minimum measured temperature.
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
+ R
6
= 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