Datasheet

AD8278/AD8279
Rev. C | Page 18 of 24
APPLICATIONS INFORMATION
CONFIGURATIONS
The AD8278 and AD8279 can be configured in several ways
(see Figure 51 to Figure 57). These configurations have excellent
gain accuracy and gain drift because they rely on the internal
matched resistors. Note that Figure 53 shows the AD8278 and
AD8279 as difference amplifiers with a midsupply reference
voltage at the noninverting input. This allows the AD8278 and
AD8279 to be used as a level shifter, which is appropriate in
single-supply applications that are referenced to midsupply.
Table 10 lists several single-ended amplifier configurations
that are not illustrated.
40k
2
3
5
1
6
20k
40k 20k
–IN
OUT
+IN
V
OUT
= ½ (V
IN+
 V
IN
)
08308-047
AD8278
Figure 51. Difference Amplifier, Gain = ½
20k
5
1
2
3
6
40k
20k 40k
–IN
OUT
+IN
V
OUT
= 2(V
IN+
 V
IN
)
08308-048
AD8278
Figure 52. Difference Amplifier, Gain = 2
40k
2
3
5
1
V
REF
= MIDSUPPLY
6
20k
40k 20k
–IN
OUT
+IN
V
OUT
= ½ (V
IN+
 V
IN
) + V
REF
08308-049
AD8278
Figure 53. Difference Amplifier, Gain = ½, Referenced to Midsupply
20k
5
1
2
3
V
REF
= MIDSUPPLY
6
40k
20k 40k
–IN
OUT
+IN
V
OUT
= 2 (V
IN+
 V
IN
) + V
REF
08308-050
AD8278
Figure 54. Difference Amplifier, Gain = 2, Referenced to Midsupply
40k
2
3
5
1
6
20k
40k
20k
IN
OUT
V
OUT
= –½V
IN
0
8308-051
AD8278
Figure 55. Inverting Amplifier, Gain = −½
40k
25
6
20k
IN
OUT
3
1
40k
20k
V
OUT
= 1.5V
IN
08308-052
AD8278
Figure 56. Noninverting Amplifier, Gain = 1.5
20k
2
3
5
1
6
40k
20k 40k
OUT
IN
V
OUT
= 2V
IN
0
8308-053
AD8278
Figure 57. Noninverting Amplifier, Gain = 2
Table 10. AD8278 Difference and Single-Ended Amplifier Configurations
Amplifier Configuration Signal Gain Pin 1 (REF) Pin 2 (VIN−) Pin 3 (VIN+) Pin 5 (SENSE)
Difference Amplifier +½ GND IN− IN+ OUT
Difference Amplifier +2 IN+ OUT GND IN−
Single-Ended Inverting Amplifier −½ GND IN GND OUT
Single-Ended Inverting Amplifier −2 GND OUT GND IN
Single-Ended Noninverting Amplifier +3⁄2 IN GND IN OUT
Single-Ended Noninverting Amplifier +3 IN OUT IN GND
Single-Ended Noninverting Amplifier +½ GND GND IN OUT
Single-Ended Noninverting Amplifier +1 IN GND GND OUT
Single-Ended Noninverting Amplifier +1 GND OUT IN GND
Single-Ended Noninverting Amplifier +2 IN OUT GND GND