Datasheet AD628 (Analog Devices)

High Common-Mode Voltage, Programmable Gain Difference Amplifier AD628 FEATURES FUNCTIONAL BLOCK DIAGRAM R R High common-mode input voltage range EXT2 EXT1 ±120 V at VS = ±15 V +VS R Gain range 0.1 to 100 G 7 6 Operating temperature range: −40°C to +85°C 100kΩ 10kΩ Supply voltage range –IN 8 Dual supply: ±2.25 V to ±18 V G = +0.1 –IN OUT –IN A2 10kΩ 5 Single supply: 4.5 V to 36 V A1 +IN Excellent ac and dc performance +IN Offset temperature stability RTI: 10 μV/°C maximum 100kΩ +IN 1 Offset: ±1.5 V mV maximum 10kΩ AD628 CMRR RTI: 75 dB minimum, dc to 500 Hz, G = +1 2 3 4 –VS VREF CFILT APPLICATIONS
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High voltage current shunt sensing
Figure 1.
Programmable logic controllers Analog input front end signal conditioning 130 +5 V, +10 V, ±5 V, ±10 V, and 4 to 20 mA 120 Isolation Sensor signal conditioning 110 Power supply monitoring 100 Electrohydraulic controls VS = ±15V 90 B) Motor controls d ( 80 RR CM GENERAL DESCRIPTION 70 VS = ±2.5V 60
The AD628 is a precision difference amplifier that combines excellent dc performance with high common-mode rejection
50
over a wide range of frequencies. When used to scale high
40
voltages, it allows simple conversion of standard control
30 10 100 1k 10k 100k
02 voltages or currents for use with single-supply ADCs. A 0 2-
FREQUENCY (Hz)
99 wideband feedback loop minimizes distortion effects due to 02 capacitor charging of Σ-Δ ADCs. Figure 2. CMRR vs. Frequency of the AD628 A reference pin (VREF) provides a dc offset for converting bipolar A precision 10 kΩ resistor connected to an external pin is to single-sided signals. The AD628 converts +5 V, +10 V, ±5 V, provided for either a low-pass filter or to attenuate large ±10 V, and 4 to 20 mA input signals to a single-ended output differential input signals. A single capacitor implements a low- within the input range of single-supply ADCs. pass filter. The AD628 operates from single and dual supplies The AD628 has an input common mode and differential mode and is available in an 8-lead SOIC_N or an 8-lead MSOP. It operating range of ±120 V. The high common mode, input operates over the standard industrial temperature range of impedance makes the device well suited for high voltage −40°C to +85°C. measurements across a shunt resistor. The inverting input of the buffer amplifier is available for making a remote Kelvin connection.
Rev. G 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 license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 www.analog.com Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 ©2002–2007 Analog Devices, Inc. All rights reserved.
Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS THEORY OF OPERATION APPLICATIONS INFORMATION GAIN ADJUSTMENT INPUT VOLTAGE RANGE VOLTAGE LEVEL CONVERSION CURRENT LOOP RECEIVER MONITORING BATTERY VOLTAGES FILTER CAPACITOR VALUES KELVIN CONNECTION OUTLINE DIMENSIONS ORDERING GUIDE