AD590_02 INTERSIL [Intersil Corporation], AD590_02 Datasheet - Page 8

• Manufacturer Part Number: AD590_02
• Description: 2-Wire, Current Output Temperature Transducer
• Manufacturer: INTERSIL [Intersil Corporation]

preserve CMR. The table below shows the suggested val-
ues. Similar scaling can be used with the ICL7126 and
ICL7136.
For all:
C
C
C
R
FIGURE 14. CENTIGRADE THERMOMETER (0
REF
lNT
OSC
OSC
SCALE
10kΩ
0.1%
C
K
F
= 0.22µF
= 0.1µF
=100pF
= 100kΩ
+
-
10mV/
AD590
V
-0.29 to +0.996
0.223 to 0.473
o
lN
-0.25 to +1.0
C
RANGE (V)
10kΩ
1µA/
44.2kΩ
FIGURE 16. COLD JUNCTION COMPENSATION FOR TYPE K THERMOCOUPLE
R
1kΩ
ZERO SET
o
2
K
40.2Ω
100Ω
115kΩ
+
-
2.7315V
+
-
ICL7611
V+
R
lNT
T
220
220
220
C
= 40µV/
(kΩ)
M +100µA
+15V
-
118kΩ
20kΩ
FULL-SCALE
ADJUST
o
K
o
V
C-100
C
2
AZ
= 10.98mV
V
0.47
0.1
0.1
1
(µF)
= 10.98mV
o
C)
AD590
8
40.2Ω
The ultra-low bias current of the ICL7611 allows the use of
large value gain resistors, keeping meter current error under
1
driving amplifier. See Figure 14.
The 50kΩ pot trims offsets in the devices whether internal or
external, so it can be used to set the size of the difference
interval. this also makes it useful for liquid level detection
(where there will be a measurable temperature difference).
See Figure 15.
The reference junction(s) should be in close thermal contact
with the AD590 case. V+ must be at least 4V, while ICL8069
current should be set at 1mA - 2mA. Calibration does not
require shorting or removal of the thermocouple: set R
V
adjust R
couple used (measured or from table) note V
buck out this voltage (i.e., set V
ple types, adjust values to the appropriate Seebeck coeffi-
cient. See Figure 16.
/
2
2
V+
%, and therefore saving the expense of an extra meter
V
(8V MIN)
= 10.98mV. If very precise measurements are needed,
-
+
-
R
2
1
FIGURE 15. DIFFERENTIAL THERMOMETER
50kΩ
SEEBECK
COEFFICIENT = 40µV/
+
V
-
4521Ω
OUT
to the exact Seebeck coefficient for the thermo-
TYPE K
V+
NO. 1
NO. 2
5MΩ
1.235V
ICL8069
+
+
-
-
10kΩ
o
K
2
741
= V
4.7µF
+
-
1
). For other thermocou-
10kΩ
V
1
(10mV/
OUT
, and set R
= (T
o
C)
2
- T
1
1
1
) x
for
to