Analog Devices AD8221AR Manual
  1. Manuals
  2. Brands
  3. Analog Devices Manuals
  4. Amplifier
  5. AD8221AR
  6. Manual
Analog Devices AD8221AR Manual

Analog Devices AD8221AR Manual

Precision instrumentation amplifier
Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual

FEATURES

Easy to use
Available in space-saving MSOP
Gain set with 1 external resistor (gain range 1 to 1000)
Wide power supply range: ±2.3 V to ±18 V
Temperature range for specified performance:
−40°C to +85°C
1
Operational up to 125°C
Excellent AC specifications
80 dB minimum CMRR to 10 kHz (G = 1)
825 kHz, –3 dB bandwidth (G = 1)
2 V/µs slew rate
Low noise
8 nV/√Hz, @ 1 kHz, maximum input voltage noise
0.25 µV p-p input noise (0.1 Hz to 10 Hz)
High accuracy dc performance (AD8221BR)
90 dB minimum CMRR (G = 1)
25 µV maximum input offset voltage
0.3 µV/°C maximum input offset drift
0.4 nA maximum input bias current

APPLICATIONS

Weigh scales
Industrial process controls
Bridge amplifiers
Precision data acquisition systems
Medical instrumentation
Strain gages
Transducer interfaces

GENERAL DESCRIPTION

The AD8221 is a gain programmable, high performance
instrumentation amplifier that delivers the industry's highest
CMRR over frequency in its class. The CMRR of instrumentation
amplifiers on the market today falls off at 200 Hz. In contrast,
the AD8221 maintains a minimum CMRR of 80 dB to 10 kHz
for all grades at G = 1. High CMRR over frequency allows the
AD8221 to reject wideband interference and line harmonics,
greatly simplifying filter requirements. Possible applications
include precision data acquisition, biomedical analysis, and
aerospace instrumentation.
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.
Precision Instrumentation Amplifier
120
110
100
90
80
70
60
50
40
10
Figure 2. Typical CMRR vs. Frequency for G = 1
Low voltage offset, low offset drift, low gain drift, high gain
accuracy, and high CMRR make this part an excellent choice
in applications that demand the best dc performance possible,
such as bridge signal conditioning.
Programmable gain affords the user design flexibility. A single
resistor sets the gain from 1 to 1000. The AD8221 operates on
both single and dual supplies and is well suited for applications
where ±10 V input voltages are encountered.
The AD8221 is available in a low cost 8-lead SOIC and 8-lead
MSOP, both of which offer the industry's best performance. The
MSOP requires half the board space of the SOIC, making it ideal
for multichannel or space-constrained applications.
Performance is specified over the entire industrial temperature
range of −40°C to +85°C for all grades. Furthermore, the AD8221
is operational from −40°C to +125°C
1
See Typical Performance Characteristics for expected operation from
85°C to 125°C.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113

CONNECTION DIAGRAM

1
+V
–IN
8
S
R
2
V
7
G
OUT
R
REF
3
6
G
+IN
5
–V
4
S
AD8221
TOP VIEW
Figure 1.
AD8221
COMPETITOR 1
COMPETITOR 2
100
1k
10k
FREQUENCY (Hz)
1
.
©2003–2011 Analog Devices, Inc. All rights reserved.
AD8221
100k
www.analog.com

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the AD8221AR and is the answer not in the manual?

Questions and answers

Related Manuals for Analog Devices AD8221AR

Summary of Contents for Analog Devices AD8221AR

  • Page 1: Features

    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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

  • Page 2: Table Of Contents

    AD8221 TABLE OF CONTENTS Features ....................1 Layout ..................18 Applications ..................1 Reference Terminal ..............19 General Description ................. 1 Power Supply Regulation and Bypassing ........ 19 Connection Diagram ............... 1 Input Bias Current Return Path ..........19 Revision History ................2 Input Protection .................

  • Page 3: Specifications

    AD8221 SPECIFICATIONS = ±15 V, V = 0 V, T = 25°C, G = 1, R = 2 kΩ, unless otherwise noted. Table 1. AR Grade BR Grade Parameter Conditions Unit COMMON-MODE REJECTION RATIO = −10 V to +10 V CMRR DC to 60 Hz with 1 kΩ...

  • Page 4: Changes To Specifications Section

    AD8221 AR Grade BR Grade Parameter Conditions Unit POWER SUPPLY Operating Range = ±2.3 V to ±18 V ±2.3 ±18 ±2.3 ±18 Quiescent Current Over Temperature T = −40°C to +85°C DYNAMIC RESPONSE Small Signal −3 dB Bandwidth G = 1 G = 10 G = 100 G = 1000...

  • Page 5: Changes To Table 2 Layout

    AD8221 AR Grade BR Grade Parameter Conditions Unit TEMPERATURE RANGE Specified Performance –40 –40 °C Operating Range –40 +125 –40 +125 °C Total RTI V = (V ) + (V /G). Does not include the effects of external resistor R One input grounded.
  • Page 6 AD8221 ARM Grade Parameter Conditions Unit REFERENCE INPUT kΩ µA IN− Voltage Range −V Gain to Output 1 ± 0.0001 POWER SUPPLY Operating Range = ±2.3 V to ±18 V ±2.3 ±18 Quiescent Current Over Temperature T = −40°C to +85°C DYNAMIC RESPONSE Small Signal –3 dB Bandwidth G = 1...
  • Page 7 AD8221 ARM Grade Parameter Conditions Unit TEMPERATURE RANGE Specified Performance −40 °C Operating Range −40 +125 °C Total RTI V = (V ) + (V /G). Does not include the effects of external resistor R One input grounded. G = 1. See Typical Performance Characteristics for expected operation between 85°C to 125°C.

  • Page 8: Absolute Maximum Ratings

    AD8221 ABSOLUTE MAXIMUM RATINGS Stresses above those listed under Absolute Maximum Ratings Table 3. may cause permanent damage to the device. This is a stress Parameter Rating rating only; functional operation of the device at these or any Supply Voltage ±18 V other conditions above those indicated in the operational Internal Power Dissipation...

  • Page 9: Pin Configuration And Function Descriptions

    AD8221 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD8221 –IN –V TOP VIEW (Not to Scale) Figure 3. Pin Configuration Table 5. Pin Function Descriptions Pin No. Mnemonic Description −IN Negative Input Terminal. Gain Setting Terminal. Place resistor across the R pins to set the gain. G = 1 + (49.4 kΩ/R Gain Setting Terminal.

  • Page 10: Typical Performance Characteristics

    AD8221 TYPICAL PERFORMANCE CHARACTERISTICS T = 25°C, V = ±15 V, R = 10 kΩ, unless otherwise noted. 1600 3500 1400 3000 1200 2500 1000 2000 1500 1000 –150 –100 –50 –0.9 –0.6 –0.3 CMR (µV/V) INPUT OFFSET CURRENT (nA) Figure 4.

  • Page 11: Changes To Figure 15

    AD8221 0.80 0.75 GAIN = 1000 0.70 GAIN = 100 = ±15V 0.65 GAIN = 10 GAIN = 1000 0.60 GAIN = 1 = ±5V 0.55 0.50 0.45 0.40 100k –15 –10 –5 COMMON-MODE VOLTAGE (V) FREQUENCY (Hz) Figure 10. I vs.
  • Page 12 AD8221 GAIN = 1000 GAIN = 100 GAIN = 10 –20 GAIN = 1 –40 –10 –60 –20 –80 –30 –100 100k –40 –20 FREQUENCY (Hz) TEMPERATURE (°C) Figure 16. Gain vs. Frequency Figure 19. CMR vs. Temperature –0 GAIN = 1000 –0.4 –0.8 GAIN = 100...

  • Page 13: Changes To Figures 32

    AD8221 = ±15V = ±15V –10 –8 –6 –4 –2 OUTPUT VOLTAGE (V) LOAD RESISTANCE ( Figure 25. Gain Nonlinearity, G = 100, R = 10 kΩ Figure 22. Output Voltage Swing vs. Load Resistance –0 = ±15V –1 SOURCING –2 –3 SINKING...

  • Page 14: Changes To Figure 33, Figure 34, And Figure 35

    AD8221 2µV/DIV 1s/DIV 5pA/DIV 1s/DIV Figure 28. 0.1 Hz to 10 Hz RTI Voltage Noise (G = 1) Figure 31. 0.1 Hz to 10 Hz Current Noise = ±15V GAIN = 1 GAIN = 10, 100, 1000 100k 0.1µV/DIV 1s/DIV FREQUENCY (Hz) Figure 29.
  • Page 15 AD8221 5V/DIV 4.9µs TO 0.01% 0.002%/DIV 5.6µs TO 0.001% 20mV/DIV 20µs/DIV 4µs/DIV Figure 34. Large Signal Pulse Response and Settling Time (G = 10), Figure 37. Small Signal Response, G = 1, R = 2 kΩ, C = 100 pF 0.002%/DIV 5V/DIV 10.3µs TO 0.01%...
  • Page 16 AD8221 1000 SETTLED TO 0.001% SETTLED TO 0.01% 20mV/DIV 1000 100µs/DIV GAIN Figure 42. Settling Time vs. Gain for a 10 V Step Figure 40. Small Signal Response, G = 1000, R = 2 kΩ, C = 100 pF SETTLED TO 0.001% SETTLED TO 0.01% OUTPUT VOLTAGE STEP SIZE (V) Figure 41.

  • Page 17: Theory Of Operation

    AD8221 THEORY OF OPERATION COMPENSATION COMPENSATION OUTPUT R1 24.7k 24.7k –V –IN –V –V –V –V –V Figure 43. Simplified Schematic The AD8221 is a monolithic instrumentation amplifier based Because the input amplifiers employ a current feedback on the classic 3-op amp topology. Input transistors Q1 and Q2 architecture, the gain-bandwidth product of the AD8221 are biased at a fixed current so that any differential input signal increases with gain, resulting in a system that does not suffer...

  • Page 18: Gain Selection

    AD8221 GAIN SELECTION Grounding The output voltage of the AD8221 is developed with respect to Placing a resistor across the R terminals set the gain of the potential on the reference terminal. Care should be taken to AD8221, which can be calculated by referring to Table 6 or tie REF to the appropriate local ground.

  • Page 19: Reference Terminal

    AD8221 REFERENCE TERMINAL As shown in Figure 43, the reference terminal, REF, is at one end of a 10 kΩ resistor. The output of the instrumentation amplifier is referenced to the voltage on the REF terminal; this AD8221 is useful when the output signal needs to be offset to a precise midsupply level.

  • Page 20: Rf Interference

    AD8221 affects the difference signal, and C affects the common- RF INTERFERENCE mode signal. Values of R and C should be chosen to minimize RF rectification is often a problem when amplifiers are used in RFI. Mismatch between the R × C at the positive input and the applications where there are strong RF signals.

  • Page 21: Updated Outline Dimensions

    AD8221 In this topology, an OP27 sets the reference voltage of the reduces the referred input noise of the amplifier to 8 nV/√Hz. AD8221. The output signal of the instrumentation amplifier is Thus, smaller signals can be measured because the noise floor is taken across the OUT pin and the REF pin.

  • Page 22: Added Die Information Section

    AD8221 DIE INFORMATION Die size: 1575 µm × 2230 µm Die thickness: 381 µm To minimize gain errors introduced by the bond wires, use Kelvin connections between the chip and the gain resistor, R , by connecting Pad 2A and Pad 2B in parallel to one end of R and Pad 3A and Pad 3B in parallel to the other end of R .

  • Page 23: Updated Outline Dimensions

    AD8221 OUTLINE DIMENSIONS 3.20 3.00 2.80 5.15 3.20 4.90 3.00 4.65 2.80 PIN 1 IDENTIFIER 0.65 BSC 0.95 15° MAX 0.85 1.10 MAX 0.75 0.80 0.15 0.23 6° 0.55 0.40 0.05 0.09 0° 0.40 0.25 COPLANARITY 0.10 COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 54.

  • Page 24: Changes To Ordering Guide

    Z = RoHS Compliant Part, # denotes RoHS compliant product may be top or bottom marked. See Typical Performance Characteristics for expected operation from 85°C to 125°C. ©2003–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.

This manual is also suitable for:

Ad8221ar-reelAd8221ar-reel7Ad8221arzAd8221arz-r7Ad8221arz-rlAd8221arm ... Show all

Table of Contents