Micropower Single-Supply
Rail-to-Rail Input/Output Op Amps
OP191/OP291/OP491
PIN CONFIGURATIONS
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
OUTA
–INA
+INA
–V
1
2
3
4
8
7
6
5
+V
NC
–INA
+INA
–V
1
2
3
4
8
7
6
5
NC
OUTB
–INB
+INB
+V
OP291
OP191
OUTA
NC
NC = NO CONNECT
Figure 1. 8-Lead Narrow-Body SOIC
Figure 2. 8-Lead Narrow-Body SOIC
Low offset voltage: 700 μV
No phase reversal
OUTA
–INA
+INA
+V
1
2
3
4
5
6
7
14 OUTD
13 –IND
12 +IND
11 –V
OUTA
–INA
+INA
+V
1
2
3
4
5
6
7
14 OUTD
13 –IND
12 +IND
11 –V
-
-
-
-
+
+
APPLICATIONS
Industrial process control
Battery-powered instrumentation
Power supply control and protection
Telecommunications
OP491
OP491
+INB
–INB
OUTB
10 +INC
+INB
–INB
OUTB
10 +INC
9
8
–INC
+
+
9
8
–INC
OUTC
OUTC
Remote sensors
Low voltage strain gage amplifiers
DAC output amplifiers
Figure 3. 14-Lead Narrow-Body SOIC
Figure 4. 14-Lead PDIP
OUTA
–INA
+INA
+V
1
2
3
4
5
6
7
14 OUTD
13 –IND
12 +IND
11 –V
OP491
+INB
–INB
OUTB
10 +INC
9
8
–INC
OUTC
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 ±± V dual supplies.
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 +12±°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.
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.
Rev. D
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