AD AD8497 Thermocouple amplifiers with cold junction compensation Datasheet

+VS
7
COLD JUNCTION
COMPENSATION
+IN
8
6
IN-AMP
–IN
OUT
5
1
AD849x
2
REF
3
–VS
SENSE
08529-001
THERMOCOUPLE
AD849x
8
+IN
7
+VS
–VS 3
6
OUT
NC 4
5
SENSE
REF 2
–
+
TOP VIEW
(Not to Scale)
NC = NO CONNECT
08529-002
–IN 1

REFERENCE
JUNCTION
PCB
TRACES
THERMOCOUPLE WIRE
AD849x
08529-004
MEASUREMENT
JUNCTION
INSULATED
EXPOSED





08529-007
GROUNDED
+VS
TEMPERATURE
SENSOR
COLD JUNCTION
COMPENSATION
+IN
5mV/°C
IN-AMP
G = 123.65
–IN
OUT
SENSE
08529-005
AD849x
–VS
REF
SENSE
ESD AND
OVERVOLTAGE
PROTECTION
10kΩ
50kΩ
A2
COLD JUNCTION
COMPENSATION
A3
10kΩ
+IN
ESD AND
OVERVOLTAGE
PROTECTION
OUT
DIFF AMP
G=5
A1
PRE-AMP
AD8494/AD8496: G = 24.73
AD8495/AD8497: G = 19.34
50kΩ
REF
08529-003
–IN
REFERENCE
JUNCTION
KEEP JUNCTION AND
AD849x AT SAME
TEMPERATURE
PCB
TRACES
WHEN USING ISOLATED THERMOCOUPLE TIPS
AD849x
08529-010
MEASUREMENT
JUNCTION
KEEP
TRACES
SHORT
THERMOCOUPLE WIRE
RAILS HIGH WITH OPEN
THERMOCOUPLE
RAILS LOW WITH OPEN
THERMOCOUPLE
WHEN USING EXPOSED OR GROUNDED THERMOCOUPLE TIPS
ELECTRICAL CONNECTION OCCURS AT TIP.
VOLTAGE MUST STAY IN INPUT VOLTAGE
RANGE OF AD849x.
INCORRECT
CORRECT
WHEN THERMOCOUPLE TIP TYPE IS UNKNOWN
REF
AD849x
REF
V
10MΩ
V
+
–
08529-006
AD8613
08529-008
AD849x
R
R
C
C
AD849x
RAILS HIGH WITH OPEN
THERMOCOUPLE
R
AD849x
RAILS LOW WITH OPEN
THERMOCOUPLE
FILTER FREQUENCY =
1
2πRC
08529-009
R
5V
+VS
7
5V
+VS
COLD JUNCTION
COMPENSATION
7
COLD JUNCTION
COMPENSATION
8
6
IN-AMP
–IN
OUT
+IN
5
1
AD849x
2
REF
3
–VS
SENSE
8
6
IN-AMP
–IN
OUT
5
1
AD849x
2
REF
3
–VS
SENSE
08529-013
+IN
08529-012
THERMOCOUPLE
3.20
3.00
2.80
8
3.20
3.00
2.80
1
5
5.15
4.90
4.65
4
PIN 1
IDENTIFIER
0.65 BSC
0.95
0.85
0.75
15° MAX
1.10 MAX
0.40
0.25
6°
0°
0.23
0.13
COMPLIANT TO JEDEC STANDARDS MO-187-AA
0.70
0.55
0.40
091709-A
0.15
0.05
COPLANARITY
0.10
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