High Performance, Low Power, Rail-to-Rail Precision Instrumentation Amplifier Data Sheet AD8422 FEATURES CONNECTION DIAGRAM Low power: 330 A maximum quiescent current AD8422 IN 1 8 +V S Rail-to-rail output R 2 7 V G OUT Low noise and distortion 3 6 R REF G 8 nV/Hz maximum input voltage noise at 1 kHz +IN 4 5 V S 0.15 V p-p RTI noise (G = 100) 0.5 ppm nonlinearity with 2 k load (G = 1) TOP VIEW (Not to Scale) Excellent ac specifications Figure 1. 8-Lead MSOP (RM), 8-Lead SOIC (R) 80 dB minimum CMRR at 10 kHz (G = 1) 20 2.2 MHz bandwidth (G = 1) R = 2k L 30 High precision dc performance (AD8422BRZ) V = 10V OUT 40 150 dB minimum CMRR (G = 1000) 50 0.04% maximum gain error (G = 1000) 60 0.3 V/C maximum input offset drift 70 0.5 nA maximum input bias current 80 G = 1000 Wide supply range 90 4.6 V to 36 V single supply G = 100 100 2.3 V to 18 V dual supply G = 10 110 Input overvoltage protection: 40 V from opposite supply G = 1 120 Gain range: 1 to 1000 130 APPLICATIONS 140 10 100 1k 5k Medical instrumentation FREQUENCY (Hz) Industrial process controls Figure 2. Total Harmonic Distortion vs. Frequency Strain gages Transducer interfaces Precision data acquisition systems Channel-isolated systems Portable instrumentation GENERAL DESCRIPTION The AD8422 is a high precision, low power, low noise, rail-to-rail The wide input range and rail-to-rail output of the AD8422 instrumentation amplifier that delivers the best performance bring all of the benefits of a high performance in-amp to single- per unit microampere in the industry. The AD8422 processes supply applications. Whether using high or low supply voltages, signals with ultralow distortion performance that is load the power savings make the AD8422 an excellent choice for independent over its full output range. high channel count or power sensitive applications on a very tight error budget. The AD8422 is the third generation development of the industry- standard AD620. The AD8422 employs new process technologies The AD8422 uses robust input protection that ensures reliability and design techniques to achieve higher dynamic range and without sacrificing noise performance. The AD8422 has high lower errors than its predecessors, while consuming less than ESD immunity, and the inputs are protected from continuous one-third of the power. The AD8422 uses the high performance voltages up to 40 V from the opposite supply rail. pinout introduced by the AD8221. A single resistor sets the gain from 1 to 1000. The reference pin Very low bias current makes the AD8422 error-free with high can be used to apply a precise offset to the output voltage. source impedance, allowing multiple sensors to be multiplexed The AD8422 is specified from 40C to +85C and has typical to the inputs. Low voltage noise and low current noise make the performance curves to 125C. It is available in 8-lead MSOP AD8422 an ideal choice for measuring a Wheatstone bridge. and 8-lead SOIC packages. Rev. A Document Feedback 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 20132015 Analog Devices, Inc. All rights reserved. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Technical Support www.analog.com Trademarks and registered trademarks are the property of their respective owners. AMPLITUDE (dBc) 11197-001 11197-102AD8422 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Architecture ................................................................................ 19 Applications ....................................................................................... 1 Gain Selection ............................................................................. 19 Connection Diagram ....................................................................... 1 Reference Terminal .................................................................... 20 General Description ......................................................................... 1 Input Voltage Range ................................................................... 20 Revision History ............................................................................... 2 Layout .......................................................................................... 20 Specifications ..................................................................................... 3 Input Bias Current Return Path ............................................... 21 SOIC Package ................................................................................ 3 Input Voltages Beyond the Supply Rails .................................. 21 MSOP Package .............................................................................. 5 Radio Frequency Interference (RFI) ........................................ 22 Absolute Maximum Ratings ............................................................ 8 Applications Information .............................................................. 23 Thermal Resistance ...................................................................... 8 Precision Bridge Conditioning ................................................. 23 ESD Caution .................................................................................. 8 Process Control Analog Input .................................................. 23 Pin Configuration and Function Descriptions ............................. 9 Outline Dimensions ....................................................................... 24 Typical Performance Characteristics ........................................... 10 Ordering Guide .......................................................................... 24 Theory of Operation ...................................................................... 19 REVISION HISTORY 1/15Rev. 0 to Rev. A Changes to Features Section............................................................ 1 Changes to SOIC Package Section and Table 1 ............................ 4 Changes to MSOP Package Section and Table 2 .......................... 5 Changes to Supply Voltage Parameter and ESD Parameter, Table 3 .................................................................... 8 Deleted Figure 12 and Figure 15, Renumbered Sequentially ... 11 Changes to Figure 10 to Figure 15 ................................................ 11 Changes to Figure 16, Figure 18, and Figure 19 ......................... 12 Changes to Figure 23 and Figure 24 ............................................. 13 Changes to Figure 31, Figure 32, and Figure 33 ......................... 14 Changes to Figure 64 ...................................................................... 23 5/13Revision 0: Initial Version Rev. A Page 2 of 24