Instrumentation amplifier application note

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Instrumentation Amplifier Application Note
Application Note May 27, 2009 AN1298.2

Table of Contents
Introduction to the Instrumentation Amplifier................................................................................................................................... 2 Review of Standard Instrumentation Amplifier Design Techniques................................................................................................ 2 Monolithic Instrumentation Amplifier Architecture ........................................................................................................................... 4 Introduction to Instrumentation Amplifier Product Family................................................................................................................ 4Instrumentation Amplifier Specifications ......................................................................................................................................... 4 Instrumentation Amplifier Product Family Theory of Operation....................................................................................................... 6 Features of Instrumentation Amplifier Product Family.................................................................................................................... 7 Care and Feeding of Instrumentation Amplifiers ............................................................................................................................. 10 ApplicationCircuits.......................................................................................................................................................................... 20 Pressure Sensor Interface Circuit ................................................................................................................................................... 21 Thermocouple Input with A/D Converter Output............................................................................................................................. 22 Thermocouple Input with 4mA to 20mA Output Current ................................................................................................................. 23 RTD Input with A/D Converter Output ............................................................................................................................................. 24 LowVoltage High Side Current Sense............................................................................................................................................ 27 Multiplexed Low Voltage Current Sense ......................................................................................................................................... 30 Bi-Directional CurrentSense........................................................................................................................................................... 32

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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2007,2009. All Rights Reserved All other trademarks mentioned are the property of their respective owners.

Application Note 1298 Introduction to the Instrumentation Amplifier
This Application Note describes the Intersil bipolar and MOS input (see Table 1). Instrumentation Amplifiers, theory of operation, advantages, and typical application circuits. These devices are micropower InstrumentationAmplifiers which deliver rail-to-rail input amplification and rail-to-rail output swing on a single 2.4V to 5V supply. These Instrumentation Amplifiers deliver excellent DC and AC specifications while consuming only 60µA typical supply current. Because they provide an independent pair of feedback terminals to set the gain and to adjust output level, these Instrumentation Amplifiers achieve high...