16 V Auto-Zero, Rail-to-Rail Output
Operational Amplifiers
AD8638/AD8639
Rev. F
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FEATURES
Low offset voltage: 9 μV maximum
Offset drift: 0.04 μV/°C maximum
Rail-to-rail output swing
5 V to 16 V single-supply or ±2.5 V to ±8 V dual-supply
operation
High gain: 136 dB typical
High CMRR: 133 dB typical
High PSRR: 143 dB typical
Very low input bias current: 40 pA maximum
Low supply current: 1.3 mA maximum
AD8639: qualified for automotive applications
APPLICATIONS
Pressure and position sensors
Strain gage amplifiers
Medical instrumentation
Thermocouple amplifiers
Automotive sensors
Precision references
Precision current sensing
GENERAL DESCRIPTION
The AD8638/AD8639 are single and dual wide bandwidth,
auto-zero amplifiers featuring rail-to-rail output swing and low
noise. These amplifiers have very low offset, drift, and bias
current. Operation is fully specified from 5 V to 16 V single
supply (±2.5 V to ±8 V dual supply).
The AD8638/AD8639 provide benefits previously found only
in expensive zero-drift or chopper-stabilized amplifiers. Using
the Analog Devices, Inc., topology, these auto-zero amplifiers
combine low cost with high accuracy and low noise. No exter-
nal capacitors are required. In addition, the AD8638/AD8639
greatly reduce the digital switching noise found in most chopper-
stabilized amplifiers.
With a typical offset voltage of only 3 μV, drift of 0.01 μV/°C,
and noise of 1.2 μV p-p (0.1 Hz to 10 Hz), the AD8638/AD8639
are 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 ranges. Many systems can take
advantage of the rail-to-rail output swing provided by the
AD8638/AD8639 to maximize signal-to-noise ratio (SNR).
PIN CONFIGURATIONS
OUT
1
V–
2
+IN
3
V+
5
–IN
4
AD8638
TOP VIEW
(Not to Scale)
06
89
5-
0
01
Figure 1. 5-Lead SOT-23 (RJ-5)
NC
1
–IN
2
+IN
3
V–
4
NC
8
V+
7
OUT
6
NC
5
NC = NO CONNECT
AD8638
TOP VIEW
(Not to Scale)
06
89
5-
0
02
Figure 2. 8-Lead SOIC_N (R-8)
OUT A 1
–IN A
2
+IN A
3
V–
4
V+
8
OUT B
7
–IN B
6
+IN B
5
AD8639
TOP VIEW
(Not to Scale)
06
89
5-
2
03
Figure 3. 8-Lead MSOP (RM-8)
8-Lead SOIC_N (R-8)
PIN 1
INDICATOR
NOTES
1. PIN 4 AND THE EXPOSED PAD
MUST BE CONNECTED TO V–.
AD8639
1
OUT A
2
–IN A
3
+IN A
4
v–
7OUT B
8V+
6 –IN B
5 +IN B
TOP VIEW
(Not to Scale)
0
689
5-
2
04
Figure 4. 8-Lead LFCSP_WD (CP-8-5)
The AD8638/AD8639 are specified for the extended industrial
temperature range (40°C to +125°C). The single AD8638 is
available in tiny 5-lead SOT-23 and 8-lead SOIC packages.
The dual AD8639 is available in 8-lead MSOP, 8-lead SOIC, and
8-lead LFCSP packages. See the Ordering Guide for automotive
grades.
The AD8638/AD8639 are members of a growing series of auto-
zero op amps offered by Analog Devices (see
Table 1).
Table 1. Auto-Zero Op Amps
Supply
2.7 V to 5 V
2.7 V to 5 V Low Power
5 V to 16 V
Single
AD8638
Dual
AD8639
Quad