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.
|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|
|AN-282: Fundamentals of Sampled Data Systems (pdf, 2131 kB)||Application Notes|
|AN-669: Effectively Applying the AD628 Precision Gain Block (pdf, 193 kB)||Application Notes|
|AN-244: A User's Guide to I.C. Instrumentation Amplifiers (pdf, 522 kB)||Application Notes|
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.
|AN-671: Reducing RFI Rectification Errors in In-Amp Circuits (pdf, 208 kB)||Application Notes|
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.
|CN-0190: Robust, Multivoltage, High Efficiency, 25 W Universal Power Supply Module with 6 V to 14 V Input (pdf, 357 kB)||Circuit Note|
|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|
(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.
High-performance Adder Uses Instrumentation Amplifiers
Make an adder circuit using instrumentation amplifiers to increase input impedance.
Simple circuit provides precision ADC interface
Single IC provides gains of 10 and –10
by Moshe Gerstenhaber and Charles Kitchin, Analog Devices, Inc. (EDN, 8/7/2003)
Input Filter Prevents Instrumentation-amp RF-Rectification Errors
by Charles Kitchin, Lew Counts, and Moshe Gerstenhaber, Analog Devices, Inc. (EDN, 11/13/2003)
|The AD8221 - Setting a New Industry Standard for Instrumentation Amplifiers (pdf, 582 kB)||Technical Articles|
|Applying Instrumentation Amplifiers Effectively: The Importance of an Input Ground Return (pdf, 508 kB)||Technical Documentation|
|Leading Inside Advertorials: Applying Instrumentation Amplifiers EffectivelyThe Importance of an Input Ground Return (pdf, 121 kB)||Overview|
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