Precision Instrumentation Amplifier AD8221 FEATURES CONNECTION DIAGRAM Easy to use 1 8 +V IN S Available in space-saving MSOP R 2 7 V OUT G Gain set with 1 external resistor (gain range 1 to 1000) 3 6 R REF G Wide power supply range: 2.3 V to 18 V 4 5 +IN V S AD8221 Temperature range for specified performance: TOP VIEW 40C to +85C 1 Figure 1. Operational up to 125C 120 Excellent AC specifications 80 dB minimum CMRR to 10 kHz (G = 1) 110 825 kHz, 3 dB bandwidth (G = 1) AD8221 100 2 V/s slew rate Low noise 90 8 nV/Hz, 1 kHz, maximum input voltage noise COMPETITOR 1 80 0.25 V p-p input noise (0.1 Hz to 10 Hz) High accuracy dc performance (AD8221BR) 70 90 dB minimum CMRR (G = 1) 60 25 V maximum input offset voltage COMPETITOR 2 0.3 V/C maximum input offset drift 50 0.4 nA maximum input bias current 40 10 100 1k 10k 100k APPLICATIONS FREQUENCY (Hz) Weigh scales Figure 2. Typical CMRR vs. Frequency for G = 1 Industrial process controls Bridge amplifiers Low voltage offset, low offset drift, low gain drift, high gain Precision data acquisition systems accuracy, and high CMRR make this part an excellent choice Medical instrumentation in applications that demand the best dc performance possible, Strain gages such as bridge signal conditioning. Transducer interfaces Programmable gain affords the user design flexibility. A single GENERAL DESCRIPTION resistor sets the gain from 1 to 1000. The AD8221 operates on both single and dual supplies and is well suited for applications The AD8221 is a gain programmable, high performance where 10 V input voltages are encountered. instrumentation amplifier that delivers the industrys highest CMRR over frequency in its class. The CMRR of instrumentation The AD8221 is available in a low cost 8-lead SOIC and 8-lead amplifiers on the market today falls off at 200 Hz. In contrast, MSOP, both of which offer the industrys best performance. The the AD8221 maintains a minimum CMRR of 80 dB to 10 kHz MSOP requires half the board space of the SOIC, making it ideal for all grades at G = 1. High CMRR over frequency allows the for multichannel or space-constrained applications. AD8221 to reject wideband interference and line harmonics, Performance is specified over the entire industrial temperature greatly simplifying filter requirements. Possible applications range of 40C to +85C for all grades. Furthermore, the AD8221 include precision data acquisition, biomedical analysis, and 1 is operational from 40C to +125C . aerospace instrumentation. 1 See Typical Performance Characteristics for expected operation from 85C to 125C. 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com 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. Fax: 781.461.3113 20032011 Analog Devices, Inc. All rights reserved. CMRR (dB) 03149-001 03149-002AD8221 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 ......................................................................... 19 Specifications ..................................................................................... 3 RF Interference ........................................................................... 20 Absolute Maximum Ratings ............................................................ 8 Precision Strain Gage ................................................................. 20 Thermal Characteristics .............................................................. 8 Conditioning 10 V Signals for a +5 V Differential Input ADC ............................................................................................. 20 ESD Caution .................................................................................. 8 AC-Coupled Instrumentation Amplifier ................................ 21 Pin Configuration and Function Descriptions ............................. 9 Die Information .............................................................................. 22 Typical Performance Characteristics ........................................... 10 Outline Dimensions ....................................................................... 23 Theory of Operation ...................................................................... 17 Ordering Guide .......................................................................... 24 Gain Selection ............................................................................. 18 REVISION HISTORY 3/11Rev. B to Rev. C Added Pin Configuration and Function Descriptions Section .. 9 Added Die Information Section ................................................... 22 Updated Outline Dimensions ....................................................... 23 Changes to Ordering Guide .......................................................... 24 9/07Rev. A to Rev. B Changes to Features .......................................................................... 1 Changes to Table 1 Layout ............................................................... 3 Changes to Table 2 Layout ............................................................... 5 Changes to Figure 15 ...................................................................... 11 Changes to Figures 32 .................................................................... 13 Changes to Figure 33, Figure 34, and Figure 35 ......................... 14 Updated Outline Dimensions ....................................................... 21 Changes to Ordering Guide .......................................................... 22 11/03Rev. 0 to Rev. A Changes to Features .......................................................................... 1 Changes to Specifications Section .................................................. 4 Changes to Theory of Operation Section .................................... 13 Changes to Gain Selection Section............................................... 14 10/03Revision 0: Initial Version Rev. C Page 2 of 24