40 A Micropower Instrumentation Amplifier with Zero Crossover Distortion AD8236 FEATURES CONNECTION DIAGRAM Low power: 40 A supply current (maximum) IN 1 8 +V S R 2 7 V Low input currents G OUT R 3 6 REF G 1 pA input bias current 4 5 +IN V S 0.5 pA input offset current AD8236 High CMRR: 110 dB CMRR, G = 100 TOP VIEW Space-saving MSOP (Not to Scale) Zero input crossover distortion Figure 1. Rail-to-rail input and output Gain set with single resistor 5.0 Operates from 1.8 V to 5.5 V 4.5 G = 5 4.0 APPLICATIONS V = 5V S V = 2.5V 3.5 REF Medical instrumentation 3.0 Low-side current sense 2.5 Portable devices 2.0 1.5 G = 5 V = 1.8V 1.0 S V = 0.9V REF 0.5 0 0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 OUTPUT VOLTAGE (V) Figure 2. Wide Common-Mode Voltage Range vs. Output Voltage GENERAL DESCRIPTION The AD8236 is the lowest power instrumentation amplifier 1 Table 1. Instrumentation Amplifiers by Category in the industry. It has rail-to-rail outputs and can operate on General Military Low High Speed voltages as low as 1.8 V. Its 40 A maximum supply current Purpose Zero Drift Grade Power PGA makes it an excellent choice in battery-powered applications. AD8220 AD8230 AD620 AD8236 AD8250 The AD8236s high input impedance, low input bias current of AD8221 AD8231 AD621 AD627 AD8251 AD8222 AD8290 AD624 AD623 AD8253 1 pA, high CMRR of 110 dB (G = 100), small size, and low power AD8228 AD8293G80 AD524 AD8223 offer tremendous value. It has a wider common-mode voltage range than typical three-op-amp instrumentation amplifiers, AD8295 AD8293G160 AD526 AD8226 making this a great solution for applications that operate on a AD8553 single 1.8 V or 3 V supply. An innovative input stage allows for AD8556 a wide rail-to-rail input voltage range without the crossover AD8557 distortion common in other designs. 1 See www.analog.com/inamps for the latest instrumentation amplifiers. The AD8236 is available in an 8-lead MSOP and is specified over the industrial temperature range of 40C to +125C. Rev. 0 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. Fax: 781.461.3113 2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. INPUT COMMON-MODE VOLTAGE (V) 08000-001 08000-002AD8236 TABLE OF CONTENTS Features .............................................................................................. 1 Layout .......................................................................................... 15 Applications ....................................................................................... 1 Reference Terminal .................................................................... 15 Connection Diagram ....................................................................... 1 Power Supply Regulation and Bypassing ................................ 15 General Description ......................................................................... 1 Input Bias Current Return Path ............................................... 16 Revision History ............................................................................... 2 Input Protection ......................................................................... 16 Specif icat ions ..................................................................................... 3 RF Interference ........................................................................... 16 Absolute Maximum Ratings ............................................................ 7 Common-Mode Input Voltage Range ..................................... 17 Maximum Power Dissipation ..................................................... 7 Applications Information .............................................................. 18 ESD Caution .................................................................................. 7 AC-Coupled Instrumentation Amplifier ................................ 18 Pin Configuration and Function Descriptions ............................. 8 Low Power Heart Rate Monitor ............................................... 19 Typical Performance Characteristics ............................................. 9 Outline Dimensions ....................................................................... 20 Theory of Operation ...................................................................... 14 Ordering Guide .......................................................................... 20 Basic Operation .......................................................................... 14 Gain Selection ............................................................................. 14 REVISION HISTORY 5/09Revision 0: Initial Version Rev. 0 Page 2 of 20