High Common-Mode Voltage, Programmable Gain Difference Amplifier AD628 FEATURES FUNCTIONAL BLOCK DIAGRAM R R EXT2 EXT1 High common-mode input voltage range 120 V at V = 15 V S +V S R G 7 6 Gain range 0.1 to 100 Operating temperature range: 40C to +85C 100k 10k Supply voltage range IN 8 G = +0.1 IN OUT Dual supply: 2.25 V to 18 V A2 5 IN 10k Single supply: 4.5 V to 36 V A1 +IN +IN Excellent ac and dc performance 100k Offset temperature stability RTI: 10 V/C maximum +IN 1 10k AD628 Offset: 1.5 V mV maximum CMRR RTI: 75 dB minimum, dc to 500 Hz, G = +1 2 3 4 V V S REF C FILT APPLICATIONS Figure 1. High voltage current shunt sensing 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 110 Sensor signal conditioning 100 Power supply monitoring V = 15V S Electrohydraulic controls 90 Motor controls 80 70 GENERAL DESCRIPTION V = 2.5V S 60 The AD628 is a precision difference amplifier that combines 50 excellent dc performance with high common-mode rejection 40 over a wide range of frequencies. When used to scale high voltages, it allows simple conversion of standard control 30 10 100 1k 10k 100k voltages or currents for use with single-supply ADCs. A FREQUENCY (Hz) wideband feedback loop minimizes distortion effects due to Figure 2. CMRR vs. Frequency of the AD628 capacitor charging of - ADCs. A reference pin (VREF) provides a dc offset for converting bipolar A precision 10 k 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 40C to +85C. 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 Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 20022007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. CMRR (dB) 02992-002 02992-001AD628 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation ...................................................................... 15 Applications....................................................................................... 1 Applications Information .............................................................. 16 General Description ......................................................................... 1 Gain Adjustment ........................................................................ 16 Functional Block Diagram .............................................................. 1 Input Voltage Range................................................................... 16 Revision History ............................................................................... 2 Voltage Level Conversion.......................................................... 17 Specifications..................................................................................... 3 Current Loop Receiver .............................................................. 18 Absolute Maximum Ratings............................................................ 7 Monitoring Battery Voltages..................................................... 18 Thermal Characteristics .............................................................. 7 Filter Capacitor Values............................................................... 19 ESD Caution.................................................................................. 7 Kelvin Connection ..................................................................... 19 Pin Configuration and Function Descriptions............................. 8 Outline Dimensions ....................................................................... 20 Typical Performance Characteristics ............................................. 9 Ordering Guide .......................................................................... 20 Test Circuits..................................................................................... 13 REVISION HISTORY 4/07Rev. F to Rev. G Changes to Absolute Maximum Ratings...................................... 7 Changes to Features.......................................................................... 1 Changes to Figure 3......................................................................... 7 Changes to Figure 22...................................................................... 11 Changes to Figure 26..................................................................... 13 Changes to Figure 25...................................................................... 13 Changes to Figure 27..................................................................... 13 Changes to Voltage Level Conversion Section............................ 17 Changes to Theory of Operation................................................. 14 Changes to Monitoring Battery Voltages Section ...................... 18 Changes to Figure 29..................................................................... 14 Changes to Figure 34...................................................................... 18 Changes to Table 5......................................................................... 15 Changes to Figure 35...................................................................... 19 Changes to Gain Adjustment Section......................................... 15 Updated Outline Dimensions ....................................................... 20 Added the Input Voltage Range Section..................................... 15 Added Figure 30 ............................................................................ 15 3/06Rev. E to Rev. F Added Figure 31 ............................................................................ 15 Changes to Table 1............................................................................ 3 Changes to Voltage Level Conversion Section .......................... 16 Changes to Figure 3.......................................................................... 7 Changes to Figure 32..................................................................... 16 Replaced Voltage Level Conversion Section ............................... 16 Changes to Table 6......................................................................... 16 Changes to Figure 32 and Figure 33............................................. 17 Changes to Figure 33 and Figure 34............................................ 17 Updated Outline Dimensions ....................................................... 19 Changes to Figure 35..................................................................... 18 Changes to Ordering Guide .......................................................... 19 Changes to Kelvin Connection Section...................................... 18 5/05Rev. D to Rev. E 6/03Rev. A to Rev. B Changes to Table 1........................................................................... 3 Changes to General Description ................................................... 1 Changes to Table 2........................................................................... 5 Changes to Specifications............................................................... 2 Changes to Figure 33.....................................................................18 Changes to Ordering Guide ........................................................... 4 3/05Rev. C to Rev. D Changes to TPCs 4, 5, and 6 .......................................................... 5 Updated Format................................................................ Universal Changes to TPC 9............................................................................ 6 Changes to Table 1........................................................................... 3 Updated Outline Dimensions...................................................... 14 Changes to Table 2........................................................................... 5 1/03Rev. 0 to Rev. A 4/04Rev. B to Rev. C Change to Ordering Guide............................................................. 4 Updated Format................................................................ Universal 11/02Rev. 0: Initial Version Changes to Specifications............................................................... 3 Rev. G Page 2 of 20