Datasheet

AD8222
Rev. A | Page 17 of 24
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.
05947-046
AD8222
1
2
3
4
12
11
9
5678
13141516
0.1µF
0.1µF
R
G1
R
G2
10
Figure 46. 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.
THERMOCOUPLE
+V
S
REF
–V
S
AD8222
CAPACITIVELY COUPLED
+V
S
REF
C
C
–V
S
AD8222
TRANSFORMER
+V
S
REF
–V
S
AD8222
INCORRECT
CAPACITIVELY COUPLED
+V
S
REF
C
R
R
C
–V
S
AD8222
1
f
HIGH-PASS
=
2πRC
THERMOCOUPLE
+V
S
REF
–V
S
10MΩ
AD8222
TRANSFORMER
+V
S
REF
–V
S
AD8222
CORRECT
0
5947-047
Figure 47. Creating an I
BIAS
Path