Datasheet

EVAL-AD5222SDZ User Guide UG-349
Rev. 0 | Page 5 of 16
Signal Amplifier
RDAC2 can be operated as an inverting or noninverting signal
amplifier supporting linear or pseudologarithmic gains. Table 6
shows the available configurations.
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
R38
R
G
WB2
+=1
(3)
where R
WB2
is the resistor between the W2 and B2 terminals.
V
IN
RDAC2
B2
R42
W2
B2
W2
V
OUT
OAVOUT
C1
10nF
R41
1.7kΩ
R38
2.7kΩ
10367-004
Figure 4. Linear Noninverting Amplifier
The noninverting amplifier with pseudologarithmic gain is
shown in Figure 5, and the gain is defined in Equation 4.
AW2
WB2
R
R
G += 1
(4)
where:
R
WB2
is the resistor between the W2 and B2 terminals.
R
AW 2
is the resistor between the A2 and W2 terminals.
V
IN
RDAC2
B2A2
R42
W2
B2
W2
V
OUT
OAVOUT
A2
C1
10nF
R41
1.7kΩ
R43
10367-005
Figure 5. Pseudologarithmic Noninverting Amplifier
R43 and R42 can be used to set the maximum and minimum
gain limits.
The inverting amplifier with linear gain is shown in Figure 6,
and the gain is defined in Equation 5.
Note that the input signal, V
IN
, must be negative.
R38
R
G
WB2
−=
(5)
where R
WB2
is the resistor between the W2 and B2 terminals.
V
IN
RDAC2
B2
R42
W2
B2
W2
V
OUT
OAVOUT
C1
10nF
R41
1.7kΩ
R38
2.7kΩ
10367-006
Figure 6. Linear Inverting Amplifier
Table 6. Amplifier Selection Link Options
Amplifier Gain Link Label
1
V
IN
Range
Noninverting Linear A27 LINEAR 0 V to V
DD
A29 NON-INVERTING
A30 NON-INVERTING
Pseudologarithmic A27 PSEUDOLOG 0 V to V
DD
A29 NON-INVERTING
A30
NON-INVERTING
Inverting Linear A27 LINEAR −V
DD
to 0 V
A29 INVERTING
A30
INVERTING
1
See Figure 14.