+15V
2
10.0V
Thermocouple
6
4
REF
102
R4
+15V –15V +15V –15V
R1
+15V
27kΩ
1
2
Isothermal
Block with
1N4148 (1)
12
2
ISO122P
10
+In
4
5
9
1
15
7
INA101
VOUT
RG
R2
R3
10
11
14
8
1MΩ
–In
13
16
3
R5
50Ω
100Ω
–15V
SEEBACK
COEFFICIENT
R6
100
Zero Adj
ISA
R2
R4
TYPE MATERIAL
(µV/°C)
(R3 = 100Ω)
(R5 + R6 = 100Ω)
Chromel
E
J
Constantan
Iron
Constantan
Chromel
Alumel
58.5
50.2
39.4
38.0
3.48kΩ
4.12kΩ
5.23kΩ
5.49kΩ
56.2kΩ
64.9kΩ
80.6kΩ
84.5kΩ
Ground Loop Through Conduit
NOTE: (1) –2.1mV/°C at 2.00µA.
K
T
Copper
Constantan
FIGURE 6. Thermocouple Amplifier with Ground Loop Elimination, Cold Junction Compensation, and Up-scale Burn-out.
11
10
3
5
4-20mA
8
1mA
1mA
+VS =15V
on PWS740
RS
XTR101
6
4
7
ISO122P
+V
16
1
3
15
14
5, 13
15
RCV420
R1 = 100Ω
2
RTD
(PT100)
9
VOUT
10
7
4
8
11
0V-5V
10
R2 = 2.5kΩ
12
2
16
–V
2mA
Gnd
–VS = –15V
on PWS740
FIGURE 7. Isolated 4-20mA Instrument Loop. (RTD shown.)
®
ISO122
9
TI [ TEXAS INSTRUMENTS ]
