Zero-Drift, Single-Supply, Rail-to-Rail
Input/Output Operational Amplifier
AD8628/AD8629
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: 120 dB
Very low input bias current: 100 pA max
Low supply current: 1.0 mA
Overload recovery time: 10 µs
No external components required
PIN CONFIGURATIONS
OUT
1
AD8628
TOP VIEW
(Not to Scale)
5
V+
V–
2
+IN
3
4
–IN
Figure 1. 5-Lead TSOT (UJ-5)
and 5-Lead SOT-23 (RT-5)
NC
1
–IN
2
+IN
3
8
NC
V+
OUT
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AD8628
7
6
5
TOP VIEW
(Not to Scale)
V–
4
NC
APPLICATIONS
Automotive sensors
Pressure and position sensors
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
Precision current sensing
Photodiode amplifier
NC = NO CONNECT
Figure 2. 8-Lead SOIC (R-8)
OUT A
1
–IN A
2
+IN A
3
8
V+
OUT B
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AD8629
7
6
–IN B
TOP VIEW
(Not to Scale)
5
+IN B
V–
4
Figure 3. 8-Lead SOIC (R-8)
OUT A
1
–IN A
2
+IN A
3
V–
4
8
V+
OUT B
–IN B
+IN B
AD8629
TOP VIEW
(Not to Scale)
7
6
5
Figure 4. 8-Lead MSOP (RM-8)
GENERAL DESCRIPTION
This new breed of amplifier has ultralow offset, drift, and bias
current. The AD8628/AD8629 are wide bandwidth auto-zero
amplifiers featuring rail-to-rail input and output swings 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 provide benefits previously found only in
expensive auto-zeroing or chopper-stabilized amplifiers. Using
Analog Devices’ new topology, these zero-drift amplifiers
combine low cost with high accuracy and low noise. (No exter-
nal capacitor is required.) In addition, the AD8628/AD8629
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 µV/°C, and noise of only 0.5 µV p-p (0 Hz to 10 Hz),
the AD8628/AD8629 are perfectly suited for applications in
which 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 to reduce
input biasing complexity and maximize SNR.
The AD8628/AD8629 are specified for the extended industrial
temperature range (−40°C to +125°C). The AD8628 is available
in tiny TSOT-23, SOT-23, and the popular 8-lead narrow SOIC
plastic packages. The AD8629 is available in the standard 8-lead
narrow SOIC and MSOP plastic packages.
Rev. C
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
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
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