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AD628:  High Common-Mode Voltage, Programmable Gain Difference Amplifier

Product Details

The AD628 is a precision difference amplifier that combines excellent dc performance with high common-mode rejection over a wide range of frequencies. When used to scale high voltages, it allows simple conversion of standard control voltages or currents for use with single-supply ADCs. A wideband feedback loop minimizes distortion effects due to capacitor charging of Σ-Δ ADCs.

A reference pin (VREF) provides a dc offset for converting bipolar to single-sided signals. The AD628 converts +5 V, +10 V, ±5 V, ±10 V, and 4 to 20 mA input signals to a single-ended output within the input range of single-supply ADCs.

The AD628 has an input common mode and differential mode operating range of ±120 V. The high common mode, input impedance makes the device well suited for high voltage measurements across a shunt resistor. The inverting input of the buffer amplifier is available for making a remote Kelvin connection.

A precision 10 kΩ resistor connected to an external pin is provided for either a low-pass filter or to attenuate large differential input signals. A single capacitor implements a low-pass filter. The AD628 operates from single and dual supplies and is available in an 8-lead SOIC_N or an 8-lead MSOP. It operates over the standard industrial temperature range of −40°C to +85°C.


  • High voltage current shunt sensing
  • Programmable logic controllers
  • Analog input front end signal conditioning
    +5 V, +10 V, ±5 V, ±10 V, and 4 to 20 mA
  • Isolation Sensor signal conditioning
  • Power supply monitoring
  • Electrohydraulic controls
  • Motor controls


  • High common-mode input voltage range
    ±120 V at VS = ±15 V
  • Gain range 0.1 to 100
  • Operating temperature range: −40°C to +85°C
  • Supply voltage range
    Dual supply: ±2.25 V to ±18 V
    Single supply: 4.5 V to 36 V
  • Excellent ac and dc performance
  • Offset temperature stability RTI: 10 μV/°C maximum
  • Offset: ±1.5 V mV maximum
  • CMRR RTI: 75 dB minimum, dc to 500 Hz,
    G = +1

Functional Block Diagram for AD628


Title Content Type File Type
AD628: High Common-Mode Voltage, Programmable Gain Difference Amplifier Data Sheet (Rev G, 04/2007) (pdf, 480 kB) Data Sheets PDF
AN-282: Fundamentals of Sampled Data Systems  (pdf, 2131 kB) Application Notes PDF
AN-669: Effectively Applying the AD628 Precision Gain Block  (pdf, 193 kB) Application Notes PDF
AN-244: A User's Guide to I.C. Instrumentation Amplifiers  (pdf, 522 kB) Application Notes PDF
AN-245: Instrumentation Amplifiers Solve Unusual Design Problems  (pdf, 543 kB)
Traditionally Considered Only for Transducer-Conditioning Applications, Instrumentation Amplifiers Bring Unique Performance Benefits to a Range of Other Applications as Well.
Application Notes PDF
AN-671: Reducing RFI Rectification Errors in In-Amp Circuits  (pdf, 208 kB) Application Notes PDF
AN-589: Ways to Optimize the Performance of a Difference Amplifier  (pdf, 115 kB)
This Application Note presents several ways to build and optimize the performance of a discrete difference amplifier. It also recommends amplifiers that will make the overall solution cost/performance competitive with monolithic instrument amplifiers.
Application Notes PDF
CN-0190: Robust, Multivoltage, High Efficiency, 25 W Universal Power Supply Module with 6 V to 14 V Input  (pdf, 357 kB) Circuit Note PDF
A Designer's Guide to Instrumentation Amplifiers (3rd Edition) Design Handbooks HTML
MS-2405: Simple Circuit Measures the RMS Value of an AC Power Line  (pdf, 234 kB) Technical Articles PDF
Auto-Zero Amplifiers  (doc, 75 kB)
A wide variety of electronic applications, especially those involving very small input signals, require signal paths with very low offset voltage and offset voltage drift over time and temperature.
Technical Articles DOC
High-performance Adder Uses Instrumentation Amplifiers
Make an adder circuit using instrumentation amplifiers to increase input impedance.
(EDN, 9/3/2009)
Technical Articles HTML
Simple circuit provides precision ADC interface
(EDN, 08/21/03)
Technical Articles HTML
Single IC provides gains of 10 and –10
by Moshe Gerstenhaber and Charles Kitchin, Analog Devices, Inc. (EDN, 8/7/2003)
Technical Articles HTML
Input Filter Prevents Instrumentation-amp RF-Rectification Errors
by Charles Kitchin, Lew Counts, and Moshe Gerstenhaber, Analog Devices, Inc. (EDN, 11/13/2003)
Technical Articles HTML
The AD8221 - Setting a New Industry Standard for Instrumentation Amplifiers  (pdf, 582 kB) Technical Articles PDF
Applying Instrumentation Amplifiers Effectively: The Importance of an Input Ground Return  (pdf, 508 kB) Technical Documentation PDF
Leading Inside Advertorials: Applying Instrumentation Amplifiers Effectively–The Importance of an Input Ground Return  (pdf, 121 kB) Overview PDF
Does Analog Devices offer any examples application circuits for Hi Speed Comparators? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD628 SPICE Macro Model SPICE Models HTML

Evaluation Kits & Symbols & Footprints

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.

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Price, packaging, availability

AD628 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD628AR-REEL Status: Last Time Buy 8 ld SOIC 8 Ind Reel, 2500 $2.48 $2.05 N  Material Info PCN/PDN Purchase
AD628ARMZ Status: Production 8 ld MSOP 8 Ind Tube, 50 $2.19 $1.82 Y  Material Info PCN Purchase
AD628ARMZ-R7 Status: Production 8 ld MSOP 8 Ind Reel, 1000 $2.19 $1.82 Y  Material Info PCN Purchase
AD628ARMZ-RL Status: Production 8 ld MSOP 8 Ind Reel, 3000 $2.19 $1.82 Y  Material Info PCN Purchase
AD628ARZ Status: Production 8 ld SOIC 8 Ind Tube, 98 $2.19 $1.82 Y  Material Info PCN Purchase Sample
AD628ARZ-R7 Status: Production 8 ld SOIC 8 Ind Reel, 1000 $2.19 $1.82 Y  Material Info PCN Purchase
AD628ARZ-RL Status: Production 8 ld SOIC 8 Ind Reel, 2500 $2.19 $1.82 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.

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