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AD8638:  16 V Auto-Zero, Rail-to-Rail Output Operational Amplifier

Product Details

Product Status:Recommended for New Designs

The AD8638/AD8639 are single and dual wide bandwidth, auto-zero amplifiers featuring rail-to-rail output swing and low noise. These amplifiers have very low offset, drift, and bias current. Operation is fully specified from 5 V to 16 V single supply (±2.5 V to ±8 V dual supply).

The AD8638/AD8639 provide benefits previously found only in expensive zero-drift or chopper-stabilized amplifiers. Using the Analog Devices, Inc., topology, these auto-zero amplifiers combine low cost with high accuracy and low noise. No external capacitors are required. In addition, the AD8638/AD8639 greatly reduce the digital switching noise found in most chopper- stabilized amplifiers.

With a typical offset voltage of only 3 μV, drift of 0.01 μV/°C, and noise of 1.2 μV p-p (0.1 Hz to 10 Hz), the AD8638/AD8639 are suited for applications in which error sources cannot be tolerated. Position and pressure sensors, medical equipment, and strain gage amplifiers benefit greatly from nearly zero drift over their operating temperature ranges. Many systems can take advantage of the rail-to-rail output swing provided by the AD8638/AD8639 to maximize signal-to-noise ratio (SNR).

The AD8638/AD8639 are specified for the extended industrial temperature range (−40°C to +125°C). The single AD8638 is available in tiny 5-lead SOT-23 and 8-lead SOIC packages. The dual AD8639 is available in 8-lead MSOP, 8-lead SOIC, and 8-lead LFCSP packages.

The AD8638/AD8639 are members of a growing series of auto- zero op amps offered by Analog Devices (see Table 1 in the data sheet).


  • Pressure and position sensors
  • Strain gage amplifiers Medical instrumentation
  • Thermocouple amplifiers Automotive sensors
  • Precision references
  • Precision current sensing

    • Chinese data sheet available
    • Low offset voltage: 9 μV maximum
    • Offset drift: 0.04 μV/°C maximum
    • Rail-to-rail output swing
    • 5 V to 16 V single-supply or ±2.5 V to ±8 V dual-supply operation
    • High gain: 136 dB typical
    • High CMRR: 133 dB typical
    • High PSRR: 143 dB typical
    • Very low input bias current: 40 pA maximum
    • Low supply current: 1.3 mA maximum

    Pin Configuration Diagram for AD8638


    Title Content Type File Type
    AD8638/AD8639: 16 V Auto-Zero, Rail-to-Rail Output Operational Amplifiers Data Sheet (Rev F, 06/2010) (pdf, 632 kB) Data Sheets PDF
    AN-1114: Lowest Noise Zero-Drift Amplifier Has 5.6 nV/√Hz Voltage Noise Density  (pdf, 182 kB) Application Notes PDF
    AN-940: Low Noise Amplifier Selection Guide for Optimal Noise Performance  (pdf, 199 kB) Application Notes PDF
    CN-0183: Precision 16-Bit, Bipolar Output Voltage Source with +12 V to ±5 V Supply  (pdf, 252 kB) Circuit Note PDF
    CN-0061: DC-Coupled, Single-Ended-to-Differential Conversion Using the AD8138 Low Distortion Differential ADC Driver and AD7357 Dual, 4.2 MSPS, 14-Bit SAR ADC  (pdf, 96 kB) Circuit Note PDF
    CN-0042: Driving the AD7366/AD7367 Bipolar SAR ADC in Low-Distortion DC-Coupled  (pdf, 130 kB) Circuit Note PDF
    Op Amp Applications Handbook Design Handbooks HTML
    MT-055: Chopper Stabilized (Auto-Zero) Precision Op Amps  (pdf, 320 kB) Tutorials PDF
    MT-052: Op Amp Noise Figure: Don't Be Misled  (pdf, 60 kB) Tutorials PDF
    MT-050: Op Amp Total Output Noise Calculations for Second-Order System  (pdf, 38 kB) Tutorials PDF
    MT-049: Op Amp Total Output Noise Calculations for Single-Pole System  (pdf, 40 kB) Tutorials PDF
    MT-048: Op Amp Noise Relationships: 1/f Noise, RMS Noise, and Equivalent Noise Bandwidth  (pdf, 81 kB) Tutorials PDF
    MT-047: Op Amp Noise  (pdf, 72 kB) Tutorials PDF
    WEBCAST: Noise Optimization in Sensor Signal Conditioning Circuits (Part I)
    This first part of a two-part series will explore the noise topic in detail and provide tips and answers to these types of questions.
    Webcasts WEBCAST
    WEBCAST: Noise Optimization in Sensor Signal Conditioning Circuits (Part II)
    This is the second part of a two-part series that explores the topic of signal noise in detail.
    Webcasts WEBCAST
    Ask the Applications Engineer - 39: Zero Drift Operational Amplifiers Analog Dialogue HTML
    Demystifying Auto-Zero Amplifiers Analog Dialogue HTML
    Amplifiers for Signal Conditioning - Section 3  (PDF, 397 kB)
    By Walt Kester, James Bryant, Walt Jung
    Technical Articles PDF
    MS-2066: Low Noise Signal Conditioning for Sensor-Based Circuits  (pdf, 589 kB) Technical Articles PDF
    Demystifying Auto-Zero Amplifiers Part 2
    by Eric Nolan and Reza Moghimi (Analog Dialogue, May 2000)
    Technical Articles HTML
    Demystifying Auto-Zero Amplifiers Part 1
    by Eric Nolan (Analog Dialogue, March 2000)
    Technical Articles HTML
    Zero-Drift Amplifiers  (pdf, 0) Overview PDF
    ICs for Programmable Logic Control and Distributed Control Systems  (pdf, 976 kB)
    Analog Devices leadership in industrial IC technology, with the development of the iCMOS™ and iPolar™ processes, has uniquely defined high voltage and low voltage integration to deliver smaller, higher performance, and more cost effective ICs for industrial systems.
    Overview PDF
    RAQs index Rarely Asked Questions HTML
    Glossary of EE Terms Glossary HTML

    Design Tools,Models,Drivers & Software

    Title Content Type File Type
    OpAmp Stability
    An applet for demonstrating stability effects in opamp buffers.
    Design Calculators HTML
    This tool will help with the selection, evaluation and troubleshooting of voltage feedback Op-Amps. It uses typical data to model the behavior of a selected amplifier. It allows a user to select an amplifier, configure a circuit, apply a signal and evaluate the performance. It is useful for checking an amplifier's spec's such as Bandwidth, Slew Rate, Input/Output Range, Gain Error, Load Current, Stability Issues and DC Errors in a given circuit.
    ADIsim Design/Simulation Tools HTML
    Analog Bridge Wizard
    The Analog Bridge Wizard recommends amplifiers and ADC's for your bridge application. Find out which op-amp or in-amp is best for your design, and view the error budget analysis for that solution.
    ADIsim Design/Simulation Tools HTML
    AD8638 SPICE Macro Model SPICE Models HTML

    Evaluation Kits & Symbols & Footprints

    Evaluation Boards & KitsView the Evaluation Boards and Kits page for documentation and purchasing

    Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

    Product Recommendations & Reference Designs

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    Price, packaging, availability

    AD8638 Model Options
    Model Package Pins Temp.
    Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
    AD8638ARJZ-R2 Status: Production 5 ld SOT-23 5 Ind Reel, 250 $1.76 $1.76 Y  Material Info PCN Purchase
    AD8638ARJZ-REEL Status: Production 5 ld SOT-23 5 Ind Reel, 10000 - $1.08 Y  Material Info PCN Purchase
    AD8638ARJZ-REEL7 Status: Production 5 ld SOT-23 5 Ind Reel, 3000 - $1.08 Y  Material Info PCN Purchase Sample
    AD8638ARZ Status: Production 8 ld SOIC 8 Ind Tube, 98 $1.28 $1.08 Y  Material Info PCN Purchase Sample
    AD8638ARZ-REEL Status: Production 8 ld SOIC 8 Ind Reel, 2500 - $1.08 Y  Material Info PCN Purchase
    AD8638ARZ-REEL7 Status: Production 8 ld SOIC 8 Ind Reel, 1000 - $1.08 Y  Material Info PCN Purchase
    Price Table Help

    The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

    EVAL-OPAMP-1 Evaluation Board
    Model Description Price RoHS View PCN/ PDN Check Inventory/
    EVAL-PRAOPAMP-1KSZ Status: Production Single KS-5 lead SC70 Evaluation Board $20.19 Yes -
    EVAL-PRAOPAMP-1RJZ Status: Production Single RJ-5 lead SOT23 Evaluation Board $20.19 Yes -
    EVAL-PRAOPAMP-1RMZ Status: Production Single RM-8 lead MSOP Evaluation Board $20.19 Yes -
    EVAL-PRAOPAMP-1RZ Status: Production Single R-8 lead SOIC Evaluation Board $20.19 Yes -

    Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.

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