ANALOG DEVICES AD8628, AD8630 Service Manual
Zero-Drift, Single-Supply, Rail-to-Rail
O
FEATURES
Lowest auto-zero amplifier noise
Low offset voltage: 1 μV
Input offset drift: 0.002 μV/°C
Rail-to-rail input and output swing
5 V single-supply operation
High gain, CMRR, and PSRR: 130 dB
Very low input bias current: 100 pA maximum
Low supply current: 1.0 mA
Overload recovery time: 50 μs
No external components required
APPLICATIONS
Automotive sensors
Pressure and position sensors
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
Precision current sensing
Photodiode amplifiers
GENERAL DESCRIPTION
This amplifier has ultralow offset, drift, and bias current.
The AD8628/AD8629/AD8630 are wide bandwidth auto-zero
amplifiers featuring rail-to-rail input and output swing and low
noise. Operation is fully specified from 2.7 V to 5 V single supply
(±1.35 V to ±2.5 V dual supply).
The AD8628/AD8629/AD8630 provide benefits previously
found only in expensive auto-zeroing or chopper-stabilized
amplifiers. Using Analog Devices, Inc., topology, these zerodrift amplifiers combine low cost with high accuracy and low
noise. No external capacitor is required. In addition, the AD8628/
AD8629/AD8630 greatly reduce the digital switching noise
found in most chopper-stabilized amplifiers.
With an offset voltage of only 1 µV, drift of less than 0.005 V/°C,
and noise of only 0.5 µV p-p (0 Hz to 10 Hz), the AD8628/
AD8629/AD8630 are 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 systems can take advantage of the rail-to-rail input and
output swings provided by the AD8628/AD8629/AD8630 to
reduce input biasing complexity and maximize SNR.
Input/Output Operational Amplifier
AD8628/AD8629/AD8630
PIN CONFIGURATIONS
UT
1
AD8628
TOP VIEW
V–
2
(Not to Scale)
+IN
3
Figure 1. 5-Lead TSOT (UJ-5) and 5-Lead SOT-23 (RJ-5)
NC
1
AD8628
–IN
2
+IN
3
TOP VIEW
(Not to Scal e)
4
V–
NC = NO CONNECT
Figure 2. 8-Lead SOIC_N (R-8)
OUT A
1
V–
AD8629
2
TOP VIEW
3
(Not to Scale)
4
–IN A
+IN A
Figure 3. 8-Lead SOIC_N (R-8) and 8-Lead MSOP (RM-8)
1
OUT A
–IN A
2
3
+IN A
+IN B
–IN B
OUT B
V+
AD8630
TOP VIEW
4
(Not to Scale)
5
6
7
Figure 4. 14-Lead SOIC_N (R-14) and 14-Lead TSSOP (RU-14)
The AD8628/AD8629/AD8630 are specified for the extended
industrial temperature range (−40°C to +125°C). The AD8628
is available in tiny 5-lead TSOT, 5-lead SOT-23, and 8-lead
narrow SOIC plastic packages. The AD8629 is available in the
standard 8-lead narrow SOIC and MSOP plastic packages. The
AD8630 quad amplifier is available in 14-lead narrow SOIC and
14-lead TSSOP plastic packages.
V+
5
–IN
4
02735-001
NC
8
V+
7
OUT
6
5
NC
02735-002
V+
8
OUT B
7
–IN B
6
5
+IN B
02735-063
OUT D
14
–IN D
13
12
+IN D
V–
11
10
+IN C
–IN C
9
OUT C
8
02735-066
Rev. G
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 ©2002–2008 Analog Devices, Inc. All rights reserved.
AD8628/AD8629/AD8630
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Pin Configurations ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Electrical Characteristics—VS = 5.0 V ....................................... 3
Electrical Characteristics—VS = 2.7 V ....................................... 4
Absolute Maximum Ratings ............................................................ 5
Thermal Characteristics .............................................................. 5
ESD Caution .................................................................................. 5
Typical Performance Characteristics ............................................. 6
Functional Description .................................................................. 14
REVISION HISTORY
6/08—Rev. F to Rev. G
Changes to Features Section............................................................ 1
Changes to Table 5 and Figure 42 Caption ................................. 12
Changes to 1/f Noise Section and Figure 49 ............................... 14
Changes to Figure 51 Caption and Figure 55 ............................. 15
Changes to Figure 57 Caption and Figure 58 Caption .............. 16
Changes to Figure 60 Caption and Figure 61 Caption .............. 17
Changes to Figure 64 ...................................................................... 18
2/08—Rev. E to Rev. F
Renamed TSOT-23 to TSOT ............................................ Universal
Deleted Figure 4 and Figure 6 ......................................................... 1
Changes to Figure 3 and Figure 4 Captions .................................. 1
Changes to Table 1 ............................................................................ 3
Changes to Table 2 ............................................................................ 4
Changes to Table 4 ............................................................................ 5
Updated Outline Dimensions ....................................................... 19
Changes to Ordering Guide .......................................................... 20
5/05—Rev. D to Rev. E
Changes to Ordering Guide .......................................................... 22
1/05—Rev. C to Rev. D
Added AD8630 ................................................................... Universal
Added Figure 5 and Figure 6 ........................................................... 1
Changes to Caption in Figure 8 and Figure 9 ............................... 7
Changes to Caption in Figure 14 .................................................... 8
Changes to Figure 17 ........................................................................ 8
Changes to Figure 23 and Figure 24 ............................................... 9
Changes to Figure 25 and Figure 26 ............................................. 10
1/f Noise ....................................................................................... 14
Peak-to-Peak Noise .................................................................... 15
Noise Behavior with First-Order, Low-Pass Filter ................. 15
Total Integrated Input-Referred Noise for First-Order Filter15
Input Overvoltage Protection ................................................... 16
Output Phase Reversal ............................................................... 16
Overload Recovery Time .......................................................... 16
Infrared Sensors .......................................................................... 17
Precision Current Shunt Sensor ............................................... 18
Output Amplifier for High Precision DACs ........................... 18
Outline Dimensions ....................................................................... 19
Ordering Guide .......................................................................... 20
Changes to Figure 31 ...................................................................... 11
Changes to Figure 40, Figure 41, Figure 42 ................................. 12
Changes to Figure 43 and Figure 44............................................. 13
Changes to Figure 51 ...................................................................... 15
Updated Outline Dimensions ....................................................... 20
Changes to Ordering Guide .......................................................... 20
10/04—Rev. B to Rev. C
Updated Formatting ........................................................... Universal
Added AD8629 ................................................................... Universal
Added SOIC and MSOP Pin Configurations ................................ 1
Added Figure 48 ............................................................................. 13
Changes to Figure 62 ...................................................................... 17
Added MSOP Package ................................................................... 19
Changes to Ordering Guide .......................................................... 22
10/03—Rev. A to Rev. B
Changes to General Description ..................................................... 1
Changes to Absolute Maximum Ratings ........................................ 4
Changes to Ordering Guide ............................................................. 4
Added TSOT-23 Package .............................................................. 15
6/03—Rev. 0 to Rev. A
Changes to Specifications ................................................................. 3
Changes to Ordering Guide ............................................................. 4
Change to Functional Description ............................................... 10
Updated Outline Dimensions ....................................................... 15
10/02—Revision 0: Initial Version
Rev. G | Page 2 of 20
AD8628/AD8629/AD8630
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS—VS = 5.0 V
VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS
Input Bias Current IB
AD8628/AD8629
AD8630
Input Offset Current IOS
Input Voltage Range
Common-Mode Rejection Ratio CMRR VCM = 0 V to 5 V 120 140
Large Signal Voltage Gain AVO R
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH R
Output Voltage Low VOL R
Short-Circuit Limit ISC
Output Current IO
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.5 V, −40°C ≤ TA ≤ +125°C 115 130
Supply Current per Amplifier ISY V
INPUT CAPACITANCE CIN
Differential
Common Mode
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ
Overload Recovery Time
Gain Bandwidth Product GBP
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz
0.1 Hz to 1.0 Hz
Voltage Noise Density en f = 1 kHz
Current Noise Density in f = 10 Hz
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C 115 130
= 10 kΩ, VO = 0.3 V to 4.7 V 125 145
L
−40°C ≤ TA ≤ +125°C 120 135
= 100 kΩ to ground 4.99 4.996
L
−40°C ≤ TA ≤ +125°C 4.99 4.995
RL = 10 kΩ to ground 4.95 4.98
−40°C ≤ TA ≤ +125°C 4.95 4.97
= 100 kΩ to V+
L
−40°C ≤ TA ≤ +125°C
RL = 10 kΩ to V+
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
−40°C ≤ TA ≤ +125°C
= VS/2 0.85 1.1 mA
O
−40°C ≤ TA ≤ +125°C
0
±25 ±50
1 5 μV
10 μV
30 100 pA
100 300 pA
1.5 nA
50 200 pA
250 pA
0.002 0.02 μV/°C
1 5 mV
2 5 mV
10 20 mV
15 20 mV
±40
±30
±15
1.0 1.2 mA
1.5
8.0
1.0
0.05
2.5
0.5
0.16
22
5
5 V
dB
dB
dB
dB
V
V
V
V
mA
mA
mA
mA
dB
pF
pF
V/μs
ms
MHz
μV p-p
μV p-p
nV/√Hz
fA/√Hz
Rev. G | Page 3 of 20
AD8628/AD8629/AD8630
ELECTRICAL CHARACTERISTICS—VS = 2.7 V
VS = 2.7 V, VCM = 1.35 V, VO = 1.4 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 1 5 μV
−40°C ≤ TA ≤ +125°C 10 μV
Input Bias Current IB
AD8628/AD8629 30 100 pA
AD8630 100 300 pA
−40°C ≤ TA ≤ +125°C 1.0 1.5 nA
Input Offset Current IOS 50 200 pA
−40°C ≤ TA ≤ +125°C 250 pA
Input Voltage Range 0 2.7 V
Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.7 V 115 130 dB
−40°C ≤ TA ≤ +125°C 110 120 dB
Large Signal Voltage Gain AVO R
−40°C ≤ TA ≤ +125°C 105 130 dB
Offset Voltage Drift ∆VOS/∆T −40°C ≤ TA ≤ +125°C 0.002 0.02 μV/°C
OUTPUT CHARACTERISTICS
Output Voltage High VOH R
−40°C ≤ TA ≤ +125°C 2.68 2.695 V
R
−40°C ≤ TA ≤ +125°C 2.67 2.675 V
Output Voltage Low VOL R
−40°C ≤ TA ≤ +125°C 2 5 mV
R
−40°C ≤ TA ≤ +125°C 15 20 mV
Short-Circuit Limit ISC ±10 ±15 mA
−40°C ≤ TA ≤ +125°C ±10 mA
Output Current IO ±10 mA
−40°C ≤ TA ≤ +125°C ±5 mA
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 2.7 V to 5.5 V, −40°C ≤ TA ≤ +125°C 115 130 dB
Supply Current per Amplifier ISY V
−40°C ≤ TA ≤ +125°C 0.9 1.2 mA
INPUT CAPACITANCE CIN
Differential 1.5 pF
Common Mode 8.0 pF
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ 1 V/μs
Overload Recovery Time 0.05 ms
Gain Bandwidth Product GBP 2 MHz
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 0.5 μV p-p
Voltage Noise Density en f = 1 kHz 22 nV/√Hz
Current Noise Density in f = 10 Hz 5 fA/√Hz
= 10 kΩ, VO = 0.3 V to 2.4 V 110 140 dB
L
= 100 kΩ to ground 2.68 2.695 V
L
= 10 kΩ to ground 2.67 2.68 V
L
= 100 kΩ to V+ 1 5 mV
L
= 10 kΩ to V+ 10 20 mV
L
= VS/2 0.75 1.0 mA
O
Rev. G | Page 4 of 20
AD8628/AD8629/AD8630
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Supply Voltage 6 V
Input Voltage GND − 0.3 V to VS + 0.3 V
Differential Input Voltage
Output Short-Circuit Duration to GND Indefinite
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +125°C
Junction Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 60 sec) 300°C
1
Differential input voltage is limited to ±5 V or the supply voltage, whichever
is less.
1
±5.0 V
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.
THERMAL CHARACTERISTICS
θJA is specified for worst-case conditions, that is, θJA is specified
for the device soldered in a circuit board for surface-mount
packages. This was measured using a standard two-layer board.
Table 4.
Package Type θJA θJC Unit
5-Lead TSOT (UJ-5) 207 61 °C/W
5-Lead SOT-23 (RJ-5) 230 146 °C/W
8-Lead SOIC_N (R-8) 158 43 °C/W
8-Lead MSOP (RM-8) 190 44 °C/W
14-Lead SOIC_N (R-14) 105 43 °C/W
14-Lead TSSOP (RU-14) 148 23 °C/W
ESD CAUTION
Rev. G | Page 5 of 20
AD8628/AD8629/AD8630
TYPICAL PERFORMANCE CHARACTERISTICS
180
VS = 2.7V
T
= 25°C
160
A
140
120
100
80
60
NUMBER OF AMPLIF IERS
40
20
0
–2.5 –1.5 –0. 5 0.5 1.5 2.5
INPUT OFFSET VOLTAGE (µV)
Figure 5. Input Offset Voltage Distribution
02735-003
100
VS = 5V
90
V
= 2.5V
CM
T
= 25°C
A
80
70
60
50
40
30
NUMBER OF AMPLIF IERS
20
10
0
–2.5 –1.5 –0.5 0.5 1.5 2.5
INPUT OFFSET VOLTAGE (µV)
Figure 8. Input Offset Voltage Distribution
02735-006
60
VS = 5V
50
40
30
20
INPUT BIAS CURRENT (pA)
10
0
012345
INPUT COMMON-MODE VOLTAGE (V)
+85°C
+25°C
–40°C
6
Figure 6. AD8628 Input Bias Current vs. Input Common-Mode Voltage
1500
VS = 5V
1000
500
0
–500
INPUT BIAS CURRENT (pA)
–1000
150°C
125°C
7
VS = 5V
T
= –40°C TO +125° C
6
A
5
4
3
2
NUMBER OF AMPLIF IERS
1
0
02735-004
0
2
4
TCVOS (nV/°C)
68
10
02735-007
Figure 9. Input Offset Voltage Drift
1k
VS = 5V
T
= 25°C
A
100
10
1
OUTPUT VOLTAGE (mV)
0.1
SOURCE
SINK
–1500
012345
INPUT COMMON-MODE VOLTAGE (V)
6
Figure 7. AD8628 Input Bias Current vs. Input Common-Mode Voltage
02735-005
Rev. G | Page 6 of 20
0.01
0.0001 0.001 0.10.01 1 10
LOAD CURRENT (mA)
Figure 10. Output Voltage to Supply Rail vs. Load Current
02735-008
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