Zero-Drift, Single-Supply, Rail-to-Rail
Input/Output Operational Amplifier

AD8628/AD8629


Rev. C
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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

APPLICATIONS
Automotive sensors
Pressure and position sensors
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
Precision current sensing
Photodiode amplifier
PIN CONFIGURATIONS
OUT 1
V– 2
+IN 3
V+5
–IN4
AD8628
TOP VIEW
(Not to Scale)
02735-001
Figure 1. 5-Lead TSOT (UJ-5)
and 5-Lead SOT-23 (RT-5)
NC 1
–IN 2
+IN 3
V– 4
NC8
V+7
OUT6
NC5
NC = NO CONNECT
AD8628
TOP VIEW
(Not to Scale)
02735-002

Figure 2. 8-Lead SOIC (R-8)
OUT A 1
–IN A 2
+IN A 3
V– 4
V+8
OUT B7
–IN B6
+IN B5
AD8629
TOP VIEW
(Not to Scale)
02735-063

Figure 3. 8-Lead SOIC (R-8)
OUT A 1
–IN A 2
+IN A 3
V– 4
V+8
OUT B7
–IN B6
+IN B5
AD8629
TOP VIEW
(Not to Scale)
02735-064
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.