Micropower Single-Supply
Rail-to-Rail Input/Output Op Amps
OP191/OP291/OP491
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
NC
1
–INA
2
+INA
3
–V
4
PIN CONFIGURATIONS
8
NC
+V
OUTA
00294-001
OUTA
1
–INA
2
+INA
3
–V
4
8
+V
OUTB
+INB
00294-002
00294-004
OP191
7
6
5
OP291
7
6
5
–INB
NC
NC = NO CONNECT
Figure 1. 8-Lead Narrow-Body SOIC
OUTA
1
–INA
2
+INA
3
+V
4
+INB
5
–INB
6
OUTB
7
14
13
12
Figure 2. 8-Lead Narrow-Body SOIC
OUTD
–IND
+IND
–V
+INC
00294-003
OUTA
1
–INA
2
+INA
3
+V
4
+INB
5
OUTB
7
-
+
+
-
-
+
+
-
14
13
12
OUTD
–IND
+IND
–V
+INC
–INC
OUTC
APPLICATIONS
Industrial process control
Battery-powered instrumentation
Power supply control and protection
Telecommunications
Remote sensors
Low voltage strain gage amplifiers
DAC output amplifiers
OP491
11
10
9
8
OP491
11
10
9
8
–INC
OUTC
–INB
6
Figure 3. 14-Lead Narrow-Body SOIC
OUTA
–INA
+INA
+V
+INB
–INB
OUTB
1
2
3
4
5
6
7
14
13
12
Figure 4. 14-Lead PDIP
OUTD
–IND
+IND
–V
+INC
OUTC
00294-005
OP491
11
10
9
8
–INC
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.
Rev. E
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©1994–2010 Analog Devices, Inc. All rights reserved.
OP191/OP291/OP491
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Electrical Specifications ............................................................... 3
Absolute Maximum Ratings............................................................ 7
Thermal Resistance ...................................................................... 7
ESD Caution .................................................................................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 17
Input Overvoltage Protection ................................................... 18
Output Voltage Phase Reversal ................................................. 18
Overdrive Recovery ................................................................... 18
Applications Information .............................................................. 19
Single 3 V Supply, Instrumentation Amplifier ....................... 19
Single-Supply RTD Amplifier ................................................... 19
A 2.5 V Reference from a 3 V Supply ...................................... 20
5 V Only, 12-Bit DAC Swings Rail-to-Rail ............................. 20
A High-Side Current Monitor .................................................. 20
A 3 V, Cold Junction Compensated Thermocouple Amplifier
....................................................................................................... 21
Single-Supply, Direct Access Arrangement for Modems ...... 21
3 V, 50 Hz/60 Hz Active Notch Filter with False Ground ..... 22
Single-Supply, Half-Wave, and Full-Wave Rectifiers ............. 22
Outline Dimensions ....................................................................... 23
Ordering Guide .......................................................................... 24
REVISION HISTORY
4/10—Rev. D to Rev. E
Changes to Input Voltage Parameter, Table 4 ............................... 7
4/06—Rev. C to Rev. D
Changes to Noise Performance, Voltage Density, Table 1 ........... 3
Changes to Noise Performance, Voltage Density, Table 2 ........... 4
Changes to Noise Performance, Voltage Density, Table 3 ........... 5
Changes to Figure 23 and Figure 24 ............................................. 10
Changes to Figure 42 ...................................................................... 13
Changes to Figure 43 ...................................................................... 14
Changes to Figure 57 ...................................................................... 16
Added Figure 58.............................................................................. 16
Changed Reference from Figure 47 to Figure 12........................ 17
Updated Outline Dimensions ....................................................... 23
Changes to Ordering Guide .......................................................... 24
3/04—Rev. B to Rev. C.
Changes to OP291 SOIC Pin Configuration .................................1
11/03—Rev. A to Rev. B.
Edits to General Description ...........................................................1
Edits to Pin Configuration ...............................................................1
Changes to Ordering Guide .............................................................5
Updated Outline Dimensions ....................................................... 19
12/02—Rev. 0 to Rev. A.
Edits to General Description ...........................................................1
Edits to Pin Configuration ...............................................................1
Changes to Ordering Guide .............................................................5
Edits to Dice Characteristics ............................................................5
Rev. E | Page 2 of 24
OP191/OP291/OP491
SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
@ V
S
= 3.0 V, V
CM
= 0.1 V, V
O
= 1.4 V, T
A
= 25°C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
OP191G
OP291G/OP491G
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Offset Voltage Drift
Bias Current Drift
Offset Current Drift
OUTPUT CHARACTERISTICS
Output Voltage High
Symbol
Conditions
Min
Typ
Max
Unit
V
OS
−40°C ≤ T
A
≤ +125°C
V
OS
−40°C ≤ T
A
≤ +125°C
I
B
−40°C ≤ T
A
≤ +125°C
I
OS
−40°C ≤ T
A
≤ +125°C
CMRR
A
VO
∆V
OS
/∆T
∆I
B
/∆T
∆I
OS
/∆T
V
OH
R
L
= 100 kΩ to GND
−40°C to +125°C
R
L
= 2 kΩ to GND
−40°C to +125°C
R
L
= 100 kΩ to V+
−40°C to +125°C
R
L
= 2 kΩ to V+
−40°C to +125°C
Sink/source
−40°C to +125°C
f = 1 MHz, A
V
= 1
V
S
= 2.7 V to 12 V
−40°C ≤ T
A
≤ +125°C
V
O
= 0 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ
R
L
= 10 kΩ
1% distortion
To 0.01%
2.95
2.90
2.8
2.70
V
CM
= 0 V to 2.9 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ, V
O
= 0.3 V to 2.7 V
−40°C ≤ T
A
≤ +125°C
0
70
65
25
80
80
30
0.1
500
1
700
1.25
65
95
11
22
3
90
87
70
50
1.1
100
20
2.99
2.98
2.9
2.80
4.5
40
μV
mV
μV
mV
nA
nA
nA
nA
V
dB
dB
V/mV
V/mV
μV/°C
pA/°C
pA/°C
V
V
V
V
mV
mV
mV
mV
mA
mA
Ω
dB
dB
μA
μA
V/μs
V/μs
kHz
μs
MHz
Degrees
dB
μV p-p
nV/√Hz
pA/√Hz
Output Voltage Low
V
OL
10
35
75
130
Short-Circuit Limit
Open-Loop Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Slew Rate
Full-Power Bandwidth
Settling Time
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
I
SC
Z
OUT
PSRR
I
SY
±8.75
±6.0
±13.50
±10.5
200
110
110
200
330
0.4
0.4
1.2
22
3
45
145
2
30
0.8
80
75
350
480
+SR
–SR
BW
P
t
S
GBP
θ
O
CS
e
n
p-p
e
n
i
n
f = 1 kHz, R
L
= 10 kΩ
0.1 Hz to 10 Hz
f = 1 kHz
Rev. E | Page 3 of 24
OP191/OP291/OP491
@ V
S
= 5.0 V, V
CM
= 0.1 V, V
O
= 1.4 V, T
A
= 25°C, unless otherwise noted. +5 V specifications are guaranteed by +3 V and ±5 V testing.
Table 2.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
OP191
OP291/OP491
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Offset Voltage Drift
Bias Current Drift
Offset Current Drift
OUTPUT CHARACTERISTICS
Output Voltage High
Symbol
Conditions
Min
Typ
Max
Unit
V
OS
−40°C ≤ T
A
≤ +125°C
V
OS
−40°C ≤ T
A
≤ +125°C
I
B
−40°C ≤ T
A
≤ +125°C
I
OS
−40°C ≤ T
A
≤ +125°C
CMRR
A
VO
∆V
OS
/∆T
∆I
B
/∆T
∆I
OS
/∆T
V
OH
V
CM
= 0 V to 4.9 V
–40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ, V
O
= 0.3 V to 4.7 V
−40°C ≤ T
A
≤ +125°C
−40°C ≤ T
A
≤ +125°C
0
70
65
25
80
80
30
0.1
500
1.0
700
1.25
65
95
11
22
5
93
90
70
50
1.1
100
20
4.99
4.98
4.85
4.75
4.5
40
μV
mV
μV
mV
nA
nA
nA
nA
V
dB
dB
V/mV
V/mV
μV/°C
pA/°C
pA/°C
V
V
V
V
mV
mV
mV
mV
mA
mA
Ω
dB
dB
μA
μA
V/μs
V/μs
kHz
μs
MHz
Degrees
dB
μV p-p
nV/√Hz
pA/√Hz
Output Voltage Low
V
OL
Short-Circuit Limit
Open-Loop Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Slew Rate
Full-Power Bandwidth
Settling Time
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
I
SC
Z
OUT
PSRR
I
SY
R
L
= 100 kΩ to GND
−40°C to +125°C
R
L
= 2 kΩ to GND
−40°C to +125°C
R
L
= 100 kΩ to V+
−40°C to +125°C
R
L
= 2 kΩ to V+
−40°C to +125°C
Sink/source
−40°C to +125°C
f = 1 MHz, A
V
= 1
V
S
= 2.7 V to 12 V
−40°C ≤ T
A
≤ +125°C
V
O
= 0 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ
R
L
= 10 kΩ
1% distortion
To 0.01%
4.95
4.90
4.8
4.65
10
35
75
155
±8.75
±6.0
±13.5
±10.5
200
110
110
220
350
0.4
0.4
1.2
22
3
45
145
2
42
0.8
80
75
400
500
+SR
–SR
BW
P
t
S
GBP
θ
O
CS
e
n
p-p
e
n
i
n
f = 1 kHz, R
L
= 10 kΩ
0.1 Hz to 10 Hz
f = 1 kHz
Rev. E | Page 4 of 24
OP191/OP291/OP491
@ V
O
= ±5.0 V, –4.9 V ≤ V
CM
≤ +4.9 V, T
A
= +25°C, unless otherwise noted.
Table 3.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
OP191
OP291/OP491
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Offset Voltage Drift
Bias Current Drift
Offset Current Drift
OUTPUT CHARACTERISTICS
Output Voltage Swing
Symbol
Conditions
Min
Typ
Max
Unit
V
OS
−40°C ≤ T
A
≤ +125°C
V
OS
−40°C ≤ T
A
≤ +125°C
I
B
−40°C ≤ T
A
≤ +125°C
I
OS
−40°C ≤ T
A
≤ +125°C
CMRR
A
VO
∆V
OS
/∆T
∆I
B
/∆T
∆I
OS
/∆T
V
O
R
L
= 100 kΩ to GND
−40°C to +125°C
R
L
= 2 kΩ to GND
–40°C ≤ T
A
≤ +125°C
Sink/source
−40°C to +125°C
f = 1 MHz, A
V
= 1
V
S
= ±5 V
−40°C ≤ T
A
≤ +125°C
V
O
= 0 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ
1% distortion
To 0.01%
±4.93
±4.90
±4.80
±4.65
±8.75
±6
V
CM
= ±5 V
−40°C ≤ T
A
≤ +125°C
R
L
= +10 kΩ, V
O
= ±4.7 V
−40°C ≤ T
A
≤ +125°C
−5
75
67
25
80
80
30
0.1
500
1
700
1.25
65
95
11
22
+5
μV
mV
μV
mV
nA
nA
nA
nA
V
dB
dB
V/mV
μV/°C
pA/°C
pA/°C
V
V
V
V
mA
mA
Ω
dB
dB
μA
μA
V/μs
kHz
μs
MHz
Degrees
dB
μV p-p
nV/√Hz
pA/√Hz
100
97
70
50
1.1
100
20
±4.99
±4.98
±4.95
±4.75
±16.00
±13
200
110
100
260
390
0.5
1.2
22
3
45
145
2
42
0.8
Short-Circuit Limit
Open-Loop Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Full-Power Bandwidth
Settling Time
Gain Bandwidth Product
Phase Margin
Channel Separation
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
I
SC
Z
OUT
PSRR
I
SY
80
75
420
550
±SR
BW
P
t
S
GBP
θ
O
CS
e
n
p-p
e
n
i
n
f = 1 kHz
0.1 Hz to 10 Hz
f = 1 kHz
Rev. E | Page 5 of 24
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