Datasheet

®
INA103
11
12
7
5
R
G
16
15
13
14
6
2
1
INA103
V
OUT
R
F
11
10
R
F
G = 1+
2R
R
G
F
NOTE: AD625 equivalent pinout.
V
IN
∆
R
F
> 10kΩ can increase noise and reduce bandwidth—see text.
FIGURE 7. Gain Adjustment of Output Stage. FIGURE 8. Use of External Resistors for Gain Set.
OUTPUT STAGE R
1
and R
3
R
2
GAIN (kΩ)(Ω)
2 1k 2.4k
5 1.2k 632Ω
10 1.2k 273Ω
(R
2
|| 12k) + R
1
+ R
3
(R
2
|| 12k)
Output Stage Gain =
11
10
7
16
15
13
14
6
2
1
INA103
V
OUT
R
3
R
2
R
1
∆
V
IN
A common problem with many IC op amps and instrumentation amplifiers is shown in (a). Here, the amplifier’s input is driven beyond its linear common-mode
range, forcing the output of the amplifier into the supply rails. The output then “folds back”, i.e., a more positive input voltage now causes the output of the amplifier
to go negative. The INA103 has protection circuitry to prevent fold-back, and as shown in (b), limits cleanly.
(a) AD625 G = 1, V
IN
= ±15V, R
L
= 600Ω
(b) INA103 G = 1, V
IN
= ±15V, R
L
= 600Ω
FIGURE 9. INA103 Overload Condition Performance.
11
10
7
V
IN
16
15
13
14
6
2
1
INA103
∆
V
OUT
R
G
V+
V–
MJ15012
100
MJ15011
(To headphone
or speaker)
Buffer inside feedback loop
Ω
11
10
7
16
15
13
14
6
2
1
INA103
20Ω
CMR
Trim
10Ω
∆
V
IN
Gain = 1V/V
(0dB)
Introduces
approximately
+0.2% Gain Error.
FIGURE 11. Increasing Output Circuit Drive.
FIGURE 10. Optional Circuit for Externally Trimming CMR.