AD628 High Common-Mode Voltage, Programmable Gain ...

1 High Common-Mode Voltage, Programmable Gain Difference Amplifier AD628 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 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. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, Box 9106, Norwood, MA 02062-9106, : Fax: 2002 2007 Analog Devices, Inc. All rights reserved. FEATURES High Common-Mode input voltage range 120 V at VS = 15 V Gain range to 100 Operating temperature range: 40 C to +85 C Supply voltage range Dual supply: V to 18 V Single supply: V to 36 V Excellent ac and dc performance Offset temperature stability RTI: 10 V/ C maximum Offset: V mV maximum CMRR RTI: 75 dB minimum, dc to 500 Hz, G = +1 APPLICATIONS 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 GENERAL DESCRIPTION The AD628 is a precision difference amplifier that combines excellent dc performance with high Common-Mode rejection over a wide range of frequencies.

2 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 - 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. FUNCTIONAL BLOCK DIAGRAM +IN IN+IN IN VSVREFREXT1RG+VSREXT2 CFILTA2A1+IN IN100k 100k 10k 10k 10k AD628 OUTG = + Figure 1. 30405060708090100110120130 CMRR (dB)FREQUENCY (Hz)100101k10k100k02992-002VS = = 15V Figure 2.

3 CMRR vs. Frequency of the AD628 A precision 10 k 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. AD628 * PRODUCT PAGE QUICK LINKSLast Content Update: 02/23/2017 COMPARABLE PARTSView a parametric search of comparable Notes AN-244: A User's Guide to Instrumentation Amplifiers AN-245: Instrumentation Amplifiers Solve Unusual Design Problems AN-282: Fundamentals of Sampled Data Systems AN-589: Ways to Optimize the Performance of a Difference Amplifier AN-669: Effectively Applying the AD628 Precision Gain Block AN-671: Reducing RFI Rectification Errors in In-Amp CircuitsData Sheet AD628 : High Common-Mode Voltage, Programmable Gain Difference Amplifier Data SheetTechnical Books A Designer's Guide to Instrumentation Amplifiers, 3rd Edition, 2006 TOOLS AND SIMULATIONS AD628 SPICE Macro ModelREFERENCE DESIGNS CN0190 REFERENCE MATERIALST echnical Articles Auto-Zero Amplifiers High-performance Adder Uses Instrumentation Amplifiers Input Filter Prevents Instrumentation-amp RF-Rectification Errors MS-2405.

4 Simple Circuit Measures the RMS Value of an AC Power Line Simple circuit provides precision ADC interface Single IC provides gains of 10 and 10 The AD8221 - Setting a New Industry Standard for Instrumentation AmplifiersDESIGN RESOURCES AD628 Material Declaration PCN-PDN Information Quality And Reliability Symbols and FootprintsDISCUSSIONSView all AD628 EngineerZone AND BUYV isit the product page to see pricing SUPPORTS ubmit a technical question or find your regional support FEEDBACKS ubmit feedback for this data page is dynamically generated by Analog Devices, Inc., and inserted into this data sheet. A dynamic change to the content on this page will not trigger a change to either the revision number or the content of the product data sheet. This dynamic page may be frequently Rev. G | Page 2 of 20 TABLE OF CONTENTS 1 1 General 1 Functional Block 1 Revision 2 3 Absolute Maximum 7 Thermal 7 ESD 7 Pin Configuration and Function 8 Typical Performance 9 Te s t C i r c u i t 13 Theory of 15 Applications 16 Gain 16 Input Voltage 16 Voltage Level 17 Current Loop 18 Monitoring Battery 18 Filter Capacitor 19 Kelvin 19 Outline 20 Ordering 20 REVISION HISTORY 4/07 Rev.

5 F to Rev. G Changes to 1 Changes to Figure 11 Changes to Figure 13 Changes to Voltage Level Conversion 17 Changes to Monitoring Battery Voltages Section .. 18 Changes to Figure 18 Changes to Figure 19 Updated Outline Dimensions .. 20 3/06 Rev. E to Rev. F Changes to Table 3 Changes to Figure 3 .. 7 Replaced Voltage Level Conversion Section .. 16 Changes to Figure 32 and Figure 17 Updated Outline Dimensions .. 19 Changes to Ordering Guide .. 19 5/05 Rev. D to Rev. E Changes to Table 3 Changes to Table 5 Changes to Figure 18 3/05 Rev. C to Rev. D Updated Format .. Universal Changes to Table 3 Changes to Table 5 4/04 Rev. B to Rev. C Updated Format .. Universal Changes to Specifications .. 3 Changes to Absolute Maximum Ratings .. 7 Changes to Figure 7 Changes to Figure 13 Changes to Figure 13 Changes to Theory of 14 Changes to Figure 14 Changes to Table 15 Changes to Gain Adjustment 15 Added the Input Voltage Range 15 Added Figure 30.

6 15 Added Figure 31 .. 15 Changes to Voltage Level Conversion Section .. 16 Changes to Figure 16 Changes to Table 16 Changes to Figure 33 and Figure 17 Changes to Figure 18 Changes to Kelvin Connection 18 6/03 Rev. A to Rev. B Changes to General Description .. 1 Changes to Specifications .. 2 Changes to Ordering Guide .. 4 Changes to TPCs 4, 5, and 6 .. 5 Changes to TPC 9 .. 6 Updated Outline Dimensions .. 14 1/03 Rev. 0 to Rev. A Change to Ordering 4 11/02 Rev. 0: Initial Version AD628 Rev. G | Page 3 of 20 SPECIFICATIONS TA = 25 C, VS = 15 V, RL = 2 k , REXT1 = 10 k , REXT2 = , VREF = 0 V, unless otherwise noted. Table 1. AD628AR AD628 ARM Parameter Conditions Min Typ Max Min Typ Max Unit DIFFERENTIAL AND OUTPUT AMPLIFIER Gain Equation G = + (1 + REXT1/REXT2) V/V Gain Range See Figure 100 100 V/V Offset Voltage VCM = 0 V; RTI of input pins2; output amplifier G = +1 + + mV vs.

7 Temperature 4 8 4 8 V/ C CMRR3 RTI of input pins; G = + to +100 75 75 dB 500 Hz 75 75 dB Minimum CMRR Over Temperature 40 C to +85 C 70 70 dB vs. Temperature 1 4 1 4 ( V/V)/ C PSRR (RTI) VS = 10 V to 18 V 77 94 77 94 dB Input Voltage Range Common Mode 120 +120 120 +120 V Differential 120 +120 120 +120 V Dynamic Response Small Signal bandwidth 3 dB G = + 600 600 kHz Full Power bandwidth 5 5 kHz Settling Time G = + , to , 100 V step 40 40 s Slew Rate V/ s Noise (RTI)

8 Spectral Density 1 kHz 300 300 nV/ Hz Hz to 10 Hz 15 15 V p-p DIFFERENTIAL AMPLIFIER Gain V/V Error + + + + % vs. Temperature 5 5 ppm/ C Nonlinearity 5 5 ppm vs. Temperature 3 10 3 10 ppm Offset Voltage RTI of input pins + + mV vs. Temperature 8 8 V/ C Input Impedance Differential 220 220 k Common Mode 55 55 k CMRR4 RTI of input pins; G = + to +100 75 75 dB 500 Hz 75 75 dB Minimum CMRR Over Temperature 40 C to +85 C 70 70 dB vs.

9 Temperature 1 4 1 4 ( V/V)/ C Output Resistance 10 10 k Error + + % AD628 Rev. G | Page 4 of 20 AD628AR AD628 ARM Parameter Conditions Min Typ Max Min Typ Max Unit OUTPUT AMPLIFIER Gain Equation G = (1 + REXT1/REXT2) V/V Nonlinearity G = +1, VOUT = 10 V ppm Offset Voltage RTI of output amp + + mV vs.

10 Temperature V/ C Output Voltage Swing RL = 10 k + + V RL = 2 k + + V Bias Current 3 3 nA Offset Current nA CMRR VCM = 13 V 130 130 dB Open-Loop Gain VOUT = 13 V 130 130 dB POWER SUPPLY Operating Range 18 18 V Quiescent Current mA TEMPERATURE RANGE 40 +85 40 +85 C 1 To use a lower gain, see the Ga section. in Adjustment2 The addition of the difference amplifier and output amplifier offset voltage does not exceed this specification. 3 Error due to common mode as seen at the output: ][10)( )(2075 GainAmplifierOutputVCMOUT =V.