Micropower Single-Supply
Rail-to-Rail Input/Output Op Amps
OP191/OP291/OP491
Rev. E
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FEATURES
Single-supply operation: 2.7 V to 12 V
Wide input voltage range
Rail-to-rail output swing
Low supply current: 300 μA/amp
Wide bandwidth: 3 MHz
Slew rate: 0.5 V/μs
Low offset voltage: 700 μV
No phase reversal
APPLICATIONS
Industrial process control
Battery-powered instrumentation
Power supply control and protection
Telecommunications
Remote sensors
Low voltage strain gage amplifiers
DAC output amplifiers
PIN CONFIGURATIONS
NC = NO CONNECT
OP191
NC 1
–INA 2
+INA 3
–V 4
NC
+V
OUTA
NC
8
7
6
5
00
29
4-
0
01
OP291
OUTA 1
–INA 2
+INA 3
–V 4
+V
OUTB
–INB
+INB
8
7
6
5
0
02
94
-00
2
Figure 1. 8-Lead Narrow-Body SOIC
Figure 2. 8-Lead Narrow-Body SOIC
OP491
OUTA 1
–INA 2
+INA 3
+V 4
OUTD
–IND
+IND
–V
14
13
12
11
+INB 5
–INB 6
OUTB 7
+INC
–INC
OUTC
10
9
8
00
29
4-
0
03
OP491
OUTA 1
–INA 2
+INA 3
+V 4
+INB 5
OUTD
–IND
+IND
–V
+INC
14
13
12
11
10
–INB 6
OUTB 7
–INC
OUTC
9
8
0
029
4-
0
04
+
-
+
-
+
-
+
-
Figure 3. 14-Lead Narrow-Body SOIC
Figure 4. 14-Lead PDIP
OP491
OUTA 1
–INA 2
+INA 3
+V
4
OUTD
–IND
+IND
–V
14
13
12
11
+INB
5
–INB
6
OUTB 7
+INC
–INC
OUTC
10
9
8
00
29
4-
0
05
Figure 5. 14-Lead TSSOP
GENERAL DESCRIPTION
The OP191, OP291, and OP491 are single, dual, and quad
micropower, single-supply, 3 MHz bandwidth amplifiers
featuring rail-to-rail inputs and outputs. All are guaranteed to
operate from a +3 V single supply as well as ±5 V dual supplies.
Fabricated on Analog Devices CBCMOS process, the OPx91
family has a unique input stage that allows the input voltage to
safely extend 10 V beyond either supply without any phase
inversion or latch-up. The output voltage swings to within
millivolts of the supplies and continues to sink or source
current all the way to the supplies.
Applications for these amplifiers include portable tele-
communications equipment, power supply control and
protection, and interface for transducers with wide output
ranges. Sensors requiring a rail-to-rail input amplifier include
Hall effect, piezo electric, and resistive transducers.
The ability to swing rail-to-rail at both the input and output
enables designers to build multistage filters in single-supply
systems and to maintain high signal-to-noise ratios.
The OP191/OP291/OP491 are specified over the extended
industrial –40°C to +125°C temperature range. The OP191
single and OP291 dual amplifiers are available in 8-lead plastic
SOIC surface-mount packages. The OP491 quad is available in a
14-lead PDIP, a narrow 14-lead SOIC package, and a 14-lead
TSSOP.