AD8222
both pins should be connected for specified performance and
optimum reliability.
The AD8222 should be decoupled with 0.1 μF bypass capacitors,
one for each supply. The positive supply decoupling capacitor
should be placed near Pin 16, and the negative supply decoupl-
ing capacitor should be placed near Pin 8. Each supply should
also be decoupled with a 10 μF tantalum capacitor. The tantalum
capacitor can be placed further away from the AD8222 and can
generally be shared by other precision integrated circuits. Figure
46 shows an example layout.
INPUT BIAS CURRENT RETURN PATH
The input bias current of the AD8222 must have a return path
to common. When the source, such as a thermocouple, cannot
provide a return current path, one should be created, as shown
in Figure 47.
INCORRECT
+V
S
CORRECT
+V
S
AD8222
REF
AD8222
REF
0.1µF
–V
S
TRANSFORMER
+V
S
–V
S
TRANSFORMER
+V
S
16
15
14
13
AD8222
1
2
R
G1
3
4
10
9
12
11
R
G2
–V
S
THERMOCOUPLE
+V
S
C
1
f
HIGH-PASS
= 2πRC
REF
C
R
05947-046
05947-047
AD8222
REF
10MΩ
AD8222
REF
–V
S
THERMOCOUPLE
+V
S
C
R
5
6
7
8
AD8222
0.1µF
C
AD8222
REF
–V
S
CAPACITIVELY COUPLED
–V
S
CAPACITIVELY COUPLED
Figure 46. Example Layout
Figure 47. Creating an I
BIAS
Path
Rev. A | Page 17 of 24
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