+15V
2
10.0V
Thermocouple
R
4
R
1
27kΩ
Isothermal
Block with
1N4148
(1)
R
G
12
+15V
1
2
1
14
13
16
15
2
9
ISO122P
10
8
7
V
OUT
6
REF
102
4
+15V –15V
+15V –15V
4 +In
5
INA101
10
11 –In
3
1MΩ
R
2
R
3
100Ω
R
6
R
5
50Ω
–15V
100
Zero Adj
ISA
TYPE
E
SEEBACK
COEFFICIENT
(
µ
V/
°
C)
58.5
50.2
39.4
38.0
R
2
(R
3
= 100
Ω
)
3.48kΩ
4.12kΩ
5.23kΩ
5.49kΩ
R
4
(R
5
+ R
6
= 100
Ω
)
56.2kΩ
64.9kΩ
80.6kΩ
84.5kΩ
MATERIAL
Chromel
Constantan
Iron
Constantan
Chromel
Alumel
Copper
Constantan
Ground Loop Through Conduit
J
NOTE: (1) –2.1mV/°C at 2.00µA.
K
T
FIGURE 6. Thermocouple Amplifier with Ground Loop Elimination, Cold Junction Compensation, and Up-scale Burn-out.
11
3
1mA
1mA
R
S
6
4
R
1
= 100Ω
RTD
(PT100)
5
10
0.01µF
8
4-20mA
+V
S
=15V
on PWS740
XTR101
7
3
16
15
14
5, 13
15
1
ISO122P
+V
9
7
8
10
2
V
OUT
0V-5V
2
RCV420
10
11
4
12
R
2
= 2.5kΩ
16
2mA
–V
Gnd
–V
S
= –15V
on PWS740
FIGURE 7. Isolated 4-20mA Instrument Loop. (RTD shown.)
®
9
ISO122
TI [ TEXAS INSTRUMENTS ]
