Analog Devices AD621 b Datasheet
Low Drift, Low Power
a
FEATURES
EASY TO USE
Pin-Strappable Gains of 10 and 100
All Errors Specified for Total System Performance
Higher Performance than Discrete In Amp Designs
Available in 8-Lead DIP and SOIC
Low Power, 1.3 mA Max Supply Current
Wide Power Supply Range (ⴞ2.3 V to ⴞ18 V)
EXCELLENT DC PERFORMANCE
0.15% Max, Total Gain Error
ⴞ5 ppm/ⴗC, Total Gain Drift
125 V Max, Total Offset Voltage
1.0 V/ⴗC Max, Offset Voltage Drift
LOW NOISE
9 nV/√Hz, @ 1 kHz, Input Voltage Noise
0.28 V p-p Noise (0.1 Hz to 10 Hz)
EXCELLENT AC SPECIFICATIONS
800 kHz Bandwidth (G = 10), 200 kHz (G = 100)
12 s Settling Time to 0.01%
APPLICATIONS
Weigh Scales
Transducer Interface and Data Acquisition Systems
Industrial Process Controls
Battery-Powered and Portable Equipment
PRODUCT DESCRIPTION
The AD621 is an easy to use, low cost, low power, high accuracy instrumentation amplifier that is ideally suited for a wide
range of applications. Its unique combination of high performance, small size and low power, outperforms discrete in amp
implementations. High functionality, low gain errors, and low
30,000
25,000
3 OP AMP
20,000
IN AMP
OP 07S)
(3
Instrumentation Amplifier
AD621
CONNECTION DIAGRAM
8-Lead Plastic Mini-DIP (N), Cerdip (Q)
and SOIC (R) Packages
–IN
+IN
S
1
2
AD621
TOP VIEW
3
(Not to Scale)
4
G = 10/100
gain drift errors are achieved by the use of internal gain setting
resistors. Fixed gains of 10 and 100 can easily be set via external
pin strapping. The AD621 is fully specified as a total system,
therefore, simplifying the design process.
For portable or remote applications, where power dissipation,
size, and weight are critical, the AD621 features a very low
supply current of 1.3 mA max and is packaged in a compact
8-lead SOIC, 8-lead plastic DIP or 8-lead cerdip. The AD621
also excels in applications requiring high total accuracy, such
as precision data acquisition systems used in weigh scales and
transducer interface circuits. Low maximum error specifications
including nonlinearity of 10 ppm, gain drift of 5 ppm/°C, 50 µV
offset voltage, and 0.6 µV/°C offset drift (“B” grade), make
possible total system performance at a lower cost than has been
previously achieved with discrete designs or with other monolithic instrumentation amplifiers.
When operating from high source impedances, as in ECG and
blood pressure monitors, the AD621 features the ideal combination of low noise and low input bias currents. Voltage noise is
specified as 9 nV/√Hz at 1 kHz and 0.28 µV p-p from 0.1 Hz to
10 Hz. Input current noise is also extremely low at 0.1 pA/√Hz.
The AD621 outperforms FET input devices with an input bias
current specification of 1.5 nA max over the full industrial temperature range.
10,000
8
G = 10/100
7
+V
6
OUTPUT
5
REF–V
S
15,000
10,000
5,000
TOTAL ERROR, ppm OF FULL SCALE
0
0205
AD621A
10 15
SUPPLY CURRENT – mA
Figure 1. Three Op Amp IA Designs vs. AD621
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
1,000
TYPICAL STANDARD
BIPOLAR INPUT
IN AMP
10
1
1k 100M10k
AD621 SUPERETA
BIPOLAR INPUT
IN AMP
100k 10M
SOURCE RESISTANCE – ⍀
1M
TOTAL INPUT VOLTAGE NOISE, G = 100 – Vp-p
100
(0.1 – 10Hz)
0.1
Figure 2. Total Voltage Noise vs. Source Resistance
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
AD621–SPECIFICATIONS
Gain = 10
(Typical @ 25ⴗC, VS = ⴞ15 V, and RL = 2 k⍀, unless otherwise noted.)
AD621A AD621B AD621S
1
Model Conditions Min Typ Max Min Typ Max Min Typ Max Unit
GAIN
Gain Error V
Nonlinearity,
V
= –10 V to +10 V RL = 2 kΩ 2 10 2 10 2 10 ppm of FS
OUT
Gain vs. Temperature –1.5 ± 5 –1.5 ± 5–1±5 ppm/°C
= ±10 V 0.15 0.05 0.15 %
OUT
TOTAL VOLTAGE OFFSET
Offset (RTI) VS = ±15 V 75 250 50 125 75 250 µV
Over Temperature V
Average TC V
Offset Referred to the
= ±5 V to ±15 V 400 215 500 µV
S
= ±5 V to ±15 V 1.0 2.5 0.6 1.5 1.0 2.5 µV/°C
S
Input vs. Supply (PSR)2VS = ±2.3 V to ± 18 V 95 120 100 120 95 120 dB
Total NOISE
Voltage Noise (RTI) 1 kHz 13 17 13 17 13 17 nV/√Hz
RTI 0.1 Hz to 10 Hz 0.55 0.55 0.8 0.55 0.8 µV p-p
Current Noise f = 1 kHz 100 100 100 fA/√Hz
0.1 Hz–10 Hz 10 10 10 pA p-p
INPUT CURRENT V
Input Bias Current 0.5 2.0 0.5 1.0 0.5 2 nA
= ±15 V
S
Over Temperature 2.5 1.5 4 nA
Average TC 3.0 3.0 8.0 pA/°C
Input Offset Current 0.3 1.0 0.3 0.5 0.3 1.0 nA
Over Temperature 1.5 0.75 2.0 nA
Average TC 1.5 1.5 8.0 pA/°C
INPUT
Input Impedance
Differential 10储210储210储2GΩ储pF
Common-Mode 10储210储210储2GΩ储pF
Input Voltage Range
Over Temperature –V
Over Temperature –V
Common-Mode Rejection
3
VS = ±2.3 V to ±5 V –VS + 1.9 +VS – 1.2 –VS + 1.9 +VS – 1.2 –VS + 1.9 +VS – 1.2 V
V
= ±5 V to ±18 V –VS + 1.9 +VS – 1.4 –VS + 1.9 +VS – 1.4 –VS + 1.9 +VS – 1.4 V
S
+ 2.1 +VS – 1.3 –VS + 2.1 +VS – 1.3 –VS + 2.1 +VS – 1.3 V
S
+ 2.1 +VS – 1.4 –VS + 2.1 +VS – 1.4 –VS + 2.3 +VS – 1.4 V
S
Ratio DC to 60 Hz with
1 kΩ Source Imbalance VCM = 0 V to ± 10 V 93 110 100 110 93 110 dB
OUTPUT
Output Swing RL = 10 kΩ,
V
= ±2.3 V to ±5 V –VS + 1.1 +VS – 1.2 –VS + 1.1 +VS – 1.2 –VS + 1.1 +VS – 1.2 V
Over Temperature –V
Over Temperature –V
Short Current Circuit ± 18 ±18 ± 18 mA
S
V
= ±5 V to ±18 V –VS + 1.2 +VS – 1.4 –VS + 1.2 +VS – 1.4 –VS + 1.2 +VS – 1.4 V
S
+ 1.4 +VS – 1.3 –VS + 1.4 +VS – 1.3 –VS + 1.6 +VS – 1.3 V
S
+ 1.6 +VS – 1.5 –VS + 1.6 +VS – 1.5 –VS + 2.3 +VS – 1.5 V
S
DYNAMIC RESPONSE
Small Signal,
–3 dB Bandwidth 800 800 800 kHz
Slew Rate 0.75 1.2 0.75 1.2 0.75 1.2 V/µs
Settling Time to 0.01% 10 V Step 12 12 12 µs
REFERENCE INPUT
R
IN
I
IN
Voltage Range –V
VIN +, V
= 0 50 60 50 60 +50 +60 µA
REF
Gain to Output 1 ± 0.0001 1 ± 0.0001 1 ± 0.0001
20 20 20 kΩ
+ 1.6 +VS – 1.6 –VS + 1.6 +VS – 1.6 VS + 1.6 +VS – 1.6 V
S
POWER SUPPLY
Operating Range ±2.3 ± 18 ±2.3 ± 18 ±2.3 ±18 V
Quiescent Current V
Over Temperature 1.1 1.6 1.1 1.6 1.1 1.6 mA
= ±2.3 V to ±18 V 0.9 1.3 0.9 1.3 0.9 1.3 mA
S
TEMPERATURE RANGE
For Specified Performance –40 to +85 –40 to +85 –55 to +125 °C
NOTES
1
See Analog Devices’ military data sheet for 883B tested specifications.
2
This is defined as the supply range over which PSRR is defined.
3
Input Voltage Range = CMV + (Gain × V
DIFF
).
Specifications subject to change without notice.
–2–
REV. B
AD621
Gain = 100
(Typical @ 25ⴗC, VS = ⴞ15 V, and RL = 2 k⍀, unless otherwise noted.)
AD621A AD621B AD621S
1
Model Conditions Min Typ Max Min Typ Max Min Typ Max Unit
GAIN
Gain Error V
Nonlinearity,
V
= –10 V to +10 V RL = 2 kΩ 2 10 2 10 2 10 ppm of FS
OUT
Gain vs. Temperature –1 ± 5–1±5–1±5 ppm/°C
= ±10 V 0.15 0.05 0.15 %
OUT
TOTAL VOLTAGE OFFSET
Offset (RTI) VS = ±15 V 35 125 25 50 35 125 µV
Over Temperature V
Average TC V
Offset Referred to the
= ±5 V to ±15 V 185 215 225 µV
S
= ±5 V to ±15 V 0.3 1.0 0.1 0.6 0.3 1.0 µV/°C
S
Input vs. Supply (PSR)2VS = ±2.3 V to ±18 V 110 140 120 140 110 140 dB
Total NOISE
Voltage Noise (RTI) 1 kHz 9 13 9 13 9 13 nV/√Hz
RTI 0.1 Hz to 10 Hz 0.28 0.28 0.4 0.28 0.4 µV p-p
Current Noise f = 1 kHz 100 100 100 fA/√Hz
0.1 Hz–10 Hz 10 10 10 pA p-p
INPUT CURRENT V
Input Bias Current 0.5 2.0 0.5 1.0 0.5 2 nA
= ±15 V
S
Over Temperature 2.5 1.5 4 nA
Average TC 3.0 3.0 8.0 pA/°C
Input Offset Current 0.3 1.0 0.3 0.5 0.3 1.0 nA
Over Temperature 1.5 0.75 2.0 nA
Average TC 1.5 1.5 8.0 pA/°C
INPUT
Input Impedance
Differential 10储210储210储2GΩ储pF
Common-Mode 10储210储210储2GΩ储pF
Input Voltage Range
Over Temperature –V
Over Temperature –V
Common-Mode Rejection
3
VS = ±2.3 V to ±5 V –VS + 1.9 +VS – 1.2 –VS + 1.9 +VS – 1.2 –VS + 1.9 +VS – 1.2 V
V
= ±5 V to ±18 V –VS + 1.9 +VS – 1.4 –VS + 1.9 +VS – 1.4 –VS + 1.9 +VS – 1.4 V
S
+ 2.1 +VS – 1.3 –VS + 2.1 +VS – 1.3 –VS + 2.1 +VS – 1.3 V
S
+ 2.1 +VS – 1.4 –VS + 2.1 +VS – 1.4 –VS + 2.3 +VS – 1.4 V
S
Ratio DC to 60 Hz with
1 kΩ Source Imbalance VCM = 0 V to ±10 V 110 130 120 130 110 130 dB
OUTPUT
Output Swing RL = 10 kΩ,
V
= ±2.3 V to ±5 V –VS + 1.1 +VS – 1.2 –VS + 1.1 +VS – 1.2 –VS + 1.1 +VS – 1.2 V
Over Temperature –V
Over Temperature –V
Short Current Circuit ± 18 ±18 ± 18 mA
S
V
= ±5 V to ±18 V –VS + 1.2 +VS – 1.4 –VS + 1.2 +VS – 1.4 –VS + 1.2 +VS – 1.4 V
S
+ 1.4 +VS – 1.3 –VS + 1.4 +VS – 1.3 –VS + 1.6 +VS – 1.3 V
S
+ 1.6 +VS – 1.5 –VS + 1.6 +VS – 1.5 –VS + 2.3 +VS – 1.5 V
S
DYNAMIC RESPONSE
Small Signal,
–3 dB Bandwidth 200 200 200 kHz
Slew Rate 0.75 1.2 0.75 1.2 0.75 1.2 V/µs
Settling Time to 0.01% 10 V Step 12 12 12 µs
REFERENCE INPUT
R
IN
I
IN
Voltage Range –V
VIN +, V
= 0 5060 5060 5060µA
REF
Gain to Output 1 ± 0.0001 1 ± 0.0001 1 ± 0.0001
20 20 20 kΩ
+ 1.6 +VS – 1.6 –VS + 1.6 +VS – 1.6 VS + 1.6 +VS – 1.6 V
S
POWER SUPPLY
Operating Range ±2.3 ± 18 ±2.3 ± 18 ±2.3 ±18 V
Quiescent Current V
Over Temperature 1.1 1.6 1.1 1.6 1.1 1.6 mA
= ±2.3 V to ±18 V 0.9 1.3 0.9 1.3 0.9 1.3 mA
S
TEMPERATURE RANGE
For Specified Performance –40 to +85 –40 to +85 –55 to +125 °C
NOTES
1
See Analog Devices’ military data sheet for 883B tested specifications.
2
This is defined as the supply range over which PSEE is defined.
3
Input Voltage Range = CMV + (Gain × V
DIFF
).
Specifications subject to change without notice.
REV. B
–3–
AD621
ABSOLUTE MAXIMUM RATINGS
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V
Internal Power Dissipation
2
. . . . . . . . . . . . . . . . . . . . 650 mW
Input Voltage (Common Mode) . . . . . . . . . . . . . . . . . . . . ± V
1
S
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . . . ±25 V
Output Short Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Storage Temperature Range (Q) . . . . . . . . . –65°C to +150°C
Storage Temperature Range (N, R) . . . . . . . –65°C to +125°C
Operating Temperature Range
AD621 (A, B) . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
AD621 (S) . . . . . . . . . . . . . . . . . . . . . . . . – 55°C to +125°C
Lead Temperature Range
(Soldering 10 seconds) . . . . . . . . . . . . . . . . . . . . . . . . 300°C
NOTES
1
Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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.
2
Specification is for device in free air:
8-Lead Plastic Package: θJA = 95°C/W
8-Lead Cerdip Package: θJA = 110°C/W
8-Lead SOIC Package: θJA = 155°C/W
ESD SUSCEPTIBILITY
ESD (electrostatic discharge) sensitive device. Electrostatic
charges as high as 4000 volts, which readily accumulate on the
human body and on test equipment, can discharge without
detection. Although the AD621 features proprietary ESD protection circuitry, permanent damage may still occur on these
devices if they are subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid any performance degradation or loss of functionality.
ORDERING GUIDE
Temperature Package Package
Model Range Description Option
1
AD621AN –40°C to +85°C 8-Lead Plastic DIP N-8
AD621BN –40°C to +85°C 8-Lead Plastic DIP N-8
AD621AR –40°C to +85°C 8-Lead Plastic SOIC R-8
AD621BR – 40°C to +85°C 8-Lead Plastic SOIC R-8
AD621SQ/883B
2
–55°C to +125°C 8-Lead Cerdip Q-8
AD621ACHIPS –40°C to +85°C Die
NOTES
1
N = Plastic DIP; Q = Cerdip; R = SOIC.
2
See Analog Devices’ military data sheet for 883B specifications.
RG 8
RG 1
METALIZATION PHOTOGRAPH
Dimensions shown in inches and (mm).
Contact factory for latest dimensions.
1.125 (3.57)
–IN
+V
S
7
2
+IN
3
OUTPUT
6
5
REFERENCE
0.0708
(2.545)
4 –V
S
–4–
REV. B
Typical Performance Characteristics–AD621
WARM-UP TIME – Minutes
2.0
0
051
CHANGE IN OFFSET VOLTAGE – V
23
1.5
1.0
0.5
4
FREQUENCY – Hz
1000
100
1
1 100k10
VOLTAGE NOISE – nV/ Hz
100 1k 10k
10
GAIN = 10
GAIN = 100
50
SAMPLE SIZE = 90
40
30
20
PERCENTAGE OF UNITS
10
0
–200 –100
INPUT OFFSET VOLTAGE – V
0 +100 +200
TPC 1. Typical Distribution of V
50
SAMPLE SIZE = 90
40
30
Gain = 10
OS,
50
SAMPLE SIZE = 90
40
30
20
PERCENTAGE OF UNITS
10
0
–800 –400
INPUT BIAS CURRENT – pA
0 +400 +800
TPC 4. Typical Distribution of Input Bias Current
20
PERCENTAGE OF UNITS
10
0
–80 –40
INPUT OFFSET VOLTAGE – V
0 +40 +80
TPC 2. Typical Distribution of VOS, Gain = 100
50
SAMPLE SIZE = 90
40
30
20
PERCENTAGE OF UNITS
10
0
–400 –200
INPUT OFFSET CURRENT – pA
0 +200 +400
TPC 3. Typical Distribution of Input Offset Current
TPC 5. Change in Input Offset Voltage vs. Warm-Up Time
TPC 6. Voltage Noise Spectral Density
REV. B
–5–
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