Zero-Drift, Single-Supply, Rail-to-Rail
Input/Output Operational Amplifiers
AD8571/AD8572/AD8574
FEATURES
Low offset voltage: 1 μV
Input offset drift: 0.005 μV/°C
Rail-to-rail input and output swing
5 V/2.7 V single-supply operation
High gain, CMRR, PSRR: 130 dB
Ultralow input bias current: 20 pA
Low supply current: 750 μA/op amp
Overload recovery time: 50 μs
No external capacitors required
NC
–IN A
+IN A
V–
1
2
3
4
PIN CONFIGURATIONS
8
NC
V+
OUT A
01104-001
AD8571
NC
1
–IN A
2
+IN A
3
8
NC
V+
7
TOP VIEW
6
(Not to Scale)
5
AD8571
7
NC = NO CONNECT
NC = NO CONNECT
Figure 1. 8-Lead MSOP
(RM Suffix)
Figure 2. 8-Lead SOIC
(R Suffix)
OUT A
1
2
8
V+
OUT B
01104-002
OUT A
1
–IN A
+IN A
V–
2
3
4
8
V+
OUT B
+IN B
01104-005
APPLICATIONS
Temperature sensors
Pressure sensors
Precision current sensing
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
–IN A
+IN A
V–
AD8572
7
6
5
AD8572
TOP VIEW
(Not to Scale)
7
6
5
TOP VIEW
3
(Not to Scale)
4
–IN B
+IN B
–IN B
Figure 3. 8-Lead TSSOP
(RU Suffix)
Figure 4. 8-Lead SOIC
(R Suffix)
OUT A
1
–IN A
2
+IN A
3
V+
4
+IN B
5
–IN B
6
OUT B
7
14
OUT D
13
–IN D
OUT A
1
–IN A
2
+IN A
3
V+
4
+IN B
5
–IN B
6
01104-003
14
13
OUT D
–IN D
+IN D
GENERAL DESCRIPTION
This family of amplifiers has ultralow offset, drift, and bias
current. The AD8571, AD8572, and AD8574 are single, dual,
and quad amplifiers, respectively, featuring rail-to-rail input
and output swings. All are guaranteed to operate from 2.7 V to
5 V single supply.
The AD857x family provides benefits previously found only in
expensive auto-zeroing or chopper-stabilized amplifiers. Using
Analog Devices, Inc. topology, these zero-drift amplifiers
combine low cost with high accuracy. (No external capacitors
are required.) Using a patented spread-spectrum auto-zero
technique, the AD857x family eliminates the intermodulation
effects from interaction of the chopping function with the
signal frequency in ac applications.
With an offset voltage of only 1 μV and drift of 0.005 μV/°C, the
AD857x family is perfectly suited for applications where error
sources cannot be tolerated. Position and pressure sensors,
medical equipment, and strain gage amplifiers benefit greatly
from nearly zero drift over their operating temperature range.
Many more systems require the rail-to-rail input and output
swings provided by the AD857x family.
AD8574
12
+IN D
AD8574
12
11
11
V–
TOP VIEW
(Not to Scale)
10
+IN C
9
8
V–
TOP VIEW
(Not to Scale)
10
+IN C
8
–IN C
OUT C
OUT B
7
OUT C
Figure 5. 14-Lead TSSOP
(RU Suffix)
Figure 6. 14-Lead SOIC
(R Suffix)
The AD857x family is specified for the extended industrial/
automotive (−40°C to +125°C) temperature range. The AD8571
single amplifier is available in 8-lead MSOP and narrow 8-lead
SOIC packages. The AD8572 dual amplifier is available in
8-lead narrow SOIC and 8-lead TSSOP surface mount packages.
The AD8574 quad amplifier is available in narrow 14-lead SOIC
and 14-lead TSSOP packages.
Rev. B
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
©2006 Analog Devices, Inc. All rights reserved.
01104-006
9
–IN C
01104-004
NC
6
OUT A
TOP VIEW
V–
4
(Not to Scale)
5
NC
AD8571/AD8572/AD8574
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description ......................................................................... 1
Pin Configurations ........................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
5 V Electrical Characteristics...................................................... 3
2.7 V Electrical Characteristics................................................... 4
Absolute Maximum Ratings............................................................ 5
Thermal Characteristics .............................................................. 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics ............................................. 6
Functional Description .................................................................. 14
Amplifier Architecture .............................................................. 14
Basic Auto-Zero Amplifier Theory.......................................... 14
Auto-Zero Phase......................................................................... 14
Amplification Phase ................................................................... 15
High Gain, CMRR, PSRR.......................................................... 16
Maximizing Performance
Through
Proper Layout ................ 16
1/f Noise Characteristics ........................................................... 17
Random Auto-Zero Correction Eliminates Intermodulation
Distortion .................................................................................... 17
Broadband and External Resistor Noise Considerations.......... 18
Output Overdrive Recovery...................................................... 18
Input Overvoltage Protection ................................................... 18
Output Phase Reversal............................................................... 18
Capacitive Load Drive ............................................................... 19
Power-Up Behavior .................................................................... 19
Applications..................................................................................... 20
5 V Precision Strain Gage Circuit ............................................ 20
3 V Instrumentation Amplifier ................................................ 20
High Accuracy Thermocouple Amplifier ............................... 20
Precision Current Meter............................................................ 21
Precision Voltage Comparator.................................................. 21
Outline Dimensions ....................................................................... 22
Ordering Guide .......................................................................... 23
REVISION HISTORY
09/06—Rev. A to Rev. B
Updated Format..................................................................Universal
Renumbered Figures ..........................................................Universal
Changes to Figure 50...................................................................... 14
Changes to Figure 51...................................................................... 15
Changes to Figure 66...................................................................... 21
Updated Outline Dimensions ....................................................... 22
Changes to Ordering Guide .......................................................... 23
07/03—Rev. 0 to Rev. A
Renumbered Figures ..........................................................Universal
Changes to Ordering Guide .............................................................4
Change to Figure 15. ...................................................................... 16
Updated Outline Dimensions....................................................... 19
10/99—Revision 0: Initial Version
Rev. B | Page 2 of 24
AD8571/AD8572/AD8574
SPECIFICATIONS
5 V ELECTRICAL CHARACTERISTICS
V
S
= 5 V, V
CM
= 2.5 V, V
O
= 2.5 V, T
A
= 25°C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
1
Offset Voltage Drift
OUTPUT CHARACTERISTICS
Output Voltage High
Symbol
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
V
OH
V
CM
= 0 V to 5 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
R
L
= 100 kΩ to GND
−40°C to +125°C
R
L
= 10 kΩ to GND
−40°C to +125°C
R
L
= 100 kΩ to V+
−40°C to +125°C
R
L
= 10 kΩ to V+
−40°C to +125°C
−40°C to +125°C
Output Current
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Overload Recovery Time
Gain Bandwidth Product
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
1
Conditions
Min
Typ
1
10
1.0
20
150
Max
5
10
50
1.5
70
200
5
Unit
μV
μV
pA
nA
pA
pA
V
dB
dB
dB
dB
μV/°C
V
V
V
V
mV
mV
mV
mV
mA
mA
mA
mA
dB
dB
μA
μA
V/μs
ms
MHz
μV p-p
μV p-p
nV/√Hz
fA/√Hz
0
120
115
125
120
140
130
145
135
0.005
4.998
4.997
4.98
4.975
1
2
10
15
±50
±40
±30
±15
130
130
850
1000
0.4
0.05
1.5
1.3
0.41
51
2
0.04
4.99
4.99
4.95
4.95
Output Voltage Low
V
OL
10
10
30
30
Short-Circuit Limit
I
SC
I
O
−40°C to +125°C
PSRR
I
SY
V
S
= 2.7 V to 5.5 V
−40°C ≤ T
A
≤ +125°C
V
O
= 0 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ
±25
120
115
975
1075
SR
GBP
e
n
p-p
e
n
p-p
e
n
i
n
0.3
0 Hz to 10 Hz
0 Hz to 1 Hz
f = 1 kHz
f = 10 Hz
Gain testing is dependent upon test bandwidth.
Rev. B | Page 3 of 24
AD8571/AD8572/AD8574
2.7 V ELECTRICAL CHARACTERISTICS
V
S
= 2.7 V, V
CM
= 1.35 V, V
O
= 1.35 V, T
A
= 25°C, unless otherwise noted.
Table 2.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
1
Offset Voltage Drift
OUTPUT CHARACTERISTICS
Output Voltage High
Symbol
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
V
OH
V
CM
= 0 V to 2.7 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ, V
O
= 0.3 V to 2.4 V
−40°C ≤ T
A
≤ +125°C
−40°C ≤ T
A
≤ +125°C
R
L
= 100 kΩ to GND
−40°C to +125°C
R
L
= 10 kΩ to GND
−40°C to +125°C
R
L
= 100 kΩ to V+
−40°C to +125°C
R
L
= 10 kΩ to V+
−40°C to +125°C
−40°C to +125°C
Output Current
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Overload Recovery Time
Gain Bandwidth Product
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
1
Conditions
Min
Typ
1
10
1.0
10
150
Max
5
10
50
1.5
50
200
2.7
Unit
μV
μV
pA
nA
pA
pA
V
dB
dB
dB
dB
μV/°C
V
V
V
V
mV
mV
mV
mV
mA
mA
mA
mA
dB
dB
μA
μA
V/μs
ms
MHz
μV p-p
nV/√Hz
fA/√Hz
0
115
110
110
105
130
130
140
130
0.005
2.697
2.696
2.68
2.675
1
2
10
15
±15
±10
±10
±5
130
130
750
950
0.5
0.05
1
2.0
94
2
0.04
2.685
2.685
2.67
2.67
Output Voltage Low
V
OL
10
10
20
20
Short-Circuit Limit
I
SC
I
O
−40°C to +125°C
PSRR
I
SY
V
S
= 2.7 V to 5.5 V
−40°C ≤ T
A
≤ +125°C
V
O
= 0 V
−40°C ≤ T
A
≤ +125°C
R
L
= 10 kΩ
±10
120
115
900
1000
SR
GBP
e
n
p-p
e
n
i
n
0 Hz to 10 Hz
f = 1 kHz
f = 10 Hz
Gain testing is dependent upon test bandwidth.
Rev. B | Page 4 of 24
AD8571/AD8572/AD8574
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
Supply Voltage
Input Voltage
Differential Input Voltage
1
ESD (Human Body Model)
Output Short-Circuit Duration to GND
Storage Temperature Range
RM, RU, and R Packages
Operating Temperature Range
AD8571A/AD8572A/AD8574A
Junction Temperature Range
RM, RU, and R Packages
Lead Temperature Range (Soldering, 60 sec)
1
THERMAL CHARACTERISTICS
Rating
6V
GND to V
S
+ 0.3 V
±5.0 V
2000 V
Indefinite
−65°C to +150°C
−40°C to +125°C
−65°C to +150°C
300°C
θ
JA
is specified for the worst-case conditions, that is, θ
JA
is
specified for a device soldered in a circuit board for SOIC and
TSSOP packages.
Table 4. Thermal Resistance
Package Type
8-Lead MSOP (RM)
8-Lead TSSOP (RU)
8-Lead SOIC (R)
14-Lead TSSOP (RU)
14-Lead SOIC (R)
θ
JA
190
240
158
180
120
θ
JC
44
43
43
36
36
Unit
°C/W
°C/W
°C/W
°C/W
°C/W
Differential input voltage is limited to ±5.0 V or the supply voltage,
whichever is less.
ESD CAUTION
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rev. B | Page 5 of 24
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