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Ultralow Power, Rail-to-Rail Output
Operational Amplifiers
OP281/OP481
FEATURES
Low supply current: 4 μA/amplifier maximum
Single-supply operation: 2.7 V to 12 V
Wide input voltage range
Rail-to-rail output swing
Low offset voltage: 1.5 mV
No phase reversal
PIN CONFIGURATIONS
OUT A
1
–IN A
2
8
V+
OUT B
–IN B
00291-001
OP281
7
6
5
TOP VIEW
+IN A
3
(Not to Scale)
V–
4
+IN B
APPLICATIONS
Comparator
Battery-powered instrumentation
Safety monitoring
Remote sensors
Low voltage strain gage amplifiers
OUT A
–IN A
+IN A
V–
1
Figure 1. 8-Lead
Narrow-Body SOIC
(R Suffix)
8
V+
OUT B
–IN B
+IN B
00291-002
2
3
4
OP281
TOP VIEW
(Not to Scale)
7
6
5
GENERAL DESCRIPTION
The OP281 and OP481 are dual and quad ultralow power
single-supply amplifiers featuring rail-to-rail outputs. Each
operates from supplies as low as 2.0 V and is specified at +3 V
and +5 V single supplies as well as ±5 V dual supplies.
Fabricated on Analog Devices’ CBCMOS process, the
OP281/OP481 feature a precision bipolar input and an output
that swings to within millivolts of the supplies, continuing to
sink or source current up to a voltage equal to the supply voltage.
Applications for these amplifiers include safety monitoring,
portable equipment, battery and power supply control, and
signal conditioning and interfacing for transducers in very low
power systems.
The output’s ability to swing rail-to-rail and not increase supply
current when the output is driven to a supply voltage enables
the OP281/OP481 to be used as comparators in very low power
systems. This is enhanced by their fast saturation recovery time.
Propagation delays are 250 μs.
The OP281/OP481 are specified over the extended industrial
temperature range (−40°C to +85°C). The OP281 dual amplifier
is available in 8-lead SOIC surface-mount and TSSOP packages.
The OP481 quad amplifier is available in narrow 14-lead SOIC
and TSSOP packages.
Figure 2. 8-Lead TSSOP
(RU Suffix)
OUT A
1
–IN A
2
+IN A
3
V+
4
+IN B
OUT B
5
14
13
OUT D
–IN D
+IN D
OP481
12
11
V–
TOP VIEW
(Not to Scale)
10
+IN C
00291-003
–IN B
6
7
9
8
–IN C
OUT C
Figure 3. 14-Lead
Narrow-Body SOIC
(R Suffix)
OUT A
–IN A
+IN A
V+
+IN B
–IN B
OUT B
1
2
3
4
5
6
7
14
13
OUT D
–IN D
+IN D
TOP VIEW
11
V–
(Not to Scale)
12
10
9
8
OP481
+IN C
–IN C
OUT C
00291-004
Figure 4. 14-Lead TSSOP
(RU Suffix)
Rev. D
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.
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 ©1996–2008 Analog Devices, Inc. All rights reserved.
OP281/OP481
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Electrical Specifications ............................................................... 3
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
Typical Performance Characteristics ............................................. 7
Applications ..................................................................................... 13
Theory of Operation .................................................................. 13
Input Overvoltage Protection ................................................... 13
Input Offset Voltage ................................................................... 13
Input Common-Mode Voltage Range ..................................... 13
Capacitive Loading..................................................................... 14
Micropower Reference Voltage Generator.............................. 14
Window Comparator ................................................................. 14
Low-Side Current Monitor ....................................................... 15
Low Voltage Half-Wave and Full-Wave Rectifiers ................. 15
Battery-Powered Telephone Headset Amplifier..................... 15
Outline Dimensions ....................................................................... 17
Ordering Guide .......................................................................... 18
REVISION HISTORY
9/08—Rev. C to Rev. D
Changes to Figure 40 ...................................................................... 14
Changes to Low-Side Current Monitor Section ......................... 15
Changes to Figure 42 ...................................................................... 15
10/07—Rev. B to Rev. C
Updated Format .................................................................. Universal
Changes to Offset Voltage Drift Condition .................................. 3
Changes to Slew Rate Symbol ......................................................... 5
Changes to Figure 8 .......................................................................... 7
Deleted SPICE Macro-Model Section ......................................... 13
Updated Outline Dimensions ....................................................... 17
Changes to Ordering Guide .......................................................... 18
3/03—Rev. A to Rev. B
Changes to Features.......................................................................... 1
2/03—Rev. 0 to Rev. A
Updated Format .................................................................. Universal
Deleted OP181 .................................................................... Universal
Updated Package Options ................................................. Universal
Deleted OP181 Pin Configurations ................................................1
Deleted Epoxy DIP Pin Configurations .........................................1
Changes to Absolute Maximum Ratings ........................................5
Changes to Ordering Guide .............................................................5
Changes to Input Offset Voltage................................................... 10
Deleted Former Figure 33 ............................................................. 10
Deleted Overdrive Recovery Time Section ................................. 11
Deleted Former Figure 36 ............................................................. 11
Deleted 8-Lead and 14-Lead Plastic DIP (N-8 and N-14)
Outline Dimensions ....................................................................... 14
Updated Outline Dimensions ....................................................... 14
Rev. D | Page 2 of 20
OP281/OP481
SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
V
S
= 3.0 V, V
CM
= 1.5 V, T
A
= 25°C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
1
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
Output Voltage Low
Short-Circuit Limit
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Turn-On Time
Saturation Recovery Time
Gain Bandwidth Product
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
1
Symbol
V
OS
I
B
I
OS
CMRR
A
VO
ΔV
OS
/∆T
ΔI
B
/ΔT
ΔI
OS
/ΔT
V
OH
V
OL
I
SC
PSRR
I
SY
Condition
Min
Typ
Max
1.5
2.5
10
7
2
Unit
mV
mV
nA
nA
V
dB
V/mV
V/mV
μV/°C
pA/°C
pA/°C
V
mV
mA
dB
μA
μA
V/ms
μs
μs
μs
kHz
Degrees
μV p-p
nV/√Hz
pA/√Hz
−40°C ≤ T
A
≤ +85°C
−40°C ≤ T
A
≤ +85°C
−40°C ≤ T
A
≤ +85°C
V
CM
= 0 V to 2.0 V, −40°C ≤ T
A
≤ +85°C
R
L
= 1 MΩ, V
O
= 0.3 V to 2.7 V
−40°C ≤ T
A
≤ +85°C
−40°C to +85°C
0
65
5
2
3
0.1
95
13
10
20
2
2.925
2.96
25
±1.1
95
3
R
L
= 100 kΩ to GND, −40°C ≤ T
A
≤ +85°C
R
L
= 100 kΩ to V+, −40°C ≤ T
A
≤ +85°C
75
V
S
= 2.7 V to 12 V, −40°C ≤ T
A
≤ +85°C
V
O
= 0 V
−40°C ≤ T
A
≤ +85°C
R
L
= 100 kΩ, C
L
= 50 pF
A
V
= 1, V
O
= 1 V
A
V
= 20, V
O
= 1 V
76
4
5
SR
GBP
φ
M
e
n
p-p
e
n
i
n
0.1 Hz to 10 Hz
f = 1 kHz
25
40
50
65
95
70
10
75
<1
V
OS
is tested under a no load condition.
Rev. D | Page 3 of 20
OP281/OP481
V
S
= 5.0 V, V
CM
= 2.5 V, T
A
= 25°C, unless otherwise noted.
Table 2.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
1
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
Output Voltage Low
Short-Circuit Limit
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Saturation Recovery Time
Gain Bandwidth Product
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
1
Symbol
V
OS
I
B
I
OS
CMRR
A
VO
ΔV
OS
/ΔT
ΔI
B
/ΔT
ΔI
OS
/ΔT
V
OH
V
OL
I
SC
PSRR
I
SY
Condition
Min
Typ
0.1
Max
1.5
2.5
10
7
4
Unit
mV
mV
nA
nA
V
dB
V/mV
V/mV
μV/°C
pA/°C
pA/°C
V
mV
mA
dB
μA
μA
V/ms
μs
kHz
Degrees
μV p-p
nV/√Hz
pA/√Hz
−40°C ≤ T
A
≤ +85°C
−40°C ≤ T
A
≤ +85°C
−40°C ≤ T
A
≤ +85°C
V
CM
= 0 V to 4.0 V, −40°C ≤ T
A
≤ +85°C
R
L
= 1 MΩ, V
O
= 0.5 V to 4.5 V
−40°C ≤ T
A
≤ +85°C
−40°C to +85°C
0
65
5
2
3
0.1
90
15
10
20
2
4.925
4.96
25
±3.5
95
3.2
R
L
= 100 kΩ to GND, −40°C ≤ T
A
≤ +85°C
R
L
= 100 kΩ to V+, −40°C ≤ T
A
≤ +85°C
75
V
S
= 2.7 V to 12 V, −40°C ≤ T
A
≤ +85°C
V
O
= 0 V
−40°C ≤ T
A
≤ +85°C
R
L
= 100 kΩ, C
L
= 50 pF
76
4
5
SR
GBP
φ
M
e
n
p-p
e
n
i
n
27
120
100
74
10
75
<1
0.1 Hz to 10 Hz
f = 1 kHz
V
OS
is tested under a no load condition.
Rev. D | Page 4 of 20