AD626BN

Low Cost, Single-Supply Differential Amplifier AD626 FEATURES Pin Selectable Gains of 10 and 100 True Single-Supply Operation Single-Supply Range of +2.4 V to +10 V Dual-Supply Range of ⴞ1.2 V to ⴞ6 V Wide Output Voltage Range of 30 mV to 4.7 V Optional Low-Pass Filtering Excellent DC Performance Low Input Offset Voltage: 500 ␮V Max Large Common-Mode Range: 0 V to +54 V Low Power: 1.2 mW (VS = +5 V) Good CMR of 90 dB Typ AC Performance Fast Settling Time: 24 ␮s (0.01%) Includes Input Protection Series Resistive Inputs (RIN = 200 k⍀) RFI Filters Included Allows 50 V Continuous Overload CONNECTION DIAGRAM 8-Lead Plastic Mini-DIP (N) and SOIC (R) Packages 200k⍀ –IN +IN ANALOG GND 2 –VS 3 G = 30 7 G = 100 6 +VS 5 OUT 100k⍀ FILTER 4 G=2 AD626 range of this amplifier is equal to 6 (+VS – 1 V) which provides a +24 V CMR while operating from a +5 V supply. Fur thermore, the AD626 features a CMR of 90 dB typ. PRODUCT DESCRIPTION The AD626 is a low cost, true single-supply differential amplifier designed for amplifying and low-pass filtering small differential voltages from sources having a large common-mode voltage. The AD626 can operate from either a single supply of +2.4 V to +10 V, or dual supplies of ±1.2 V to ±6 V. The input common-mode The amplifier’s inputs are protected against continuous overload of up to 50 V, and RFI filters are included in the attenuator network. The output range is +0.03 V to +4.9 V using a +5 V supply. The amplifier provides a preset gain of 10, but gains between 10 and 100 can be easily configured with an external resistor. Furthermore, a gain of 100 is available by connecting the G = 100 pin to analog ground. The AD626 also offers low-pass filter capability by connecting a capacitor between the filter pin and analog ground. The AD626A and AD626B operate over the industrial temperature range of –40°C to +85°C. The AD626 is available in two 8-lead packages: a plastic mini-DIP and SOIC. 25 120 100 G = 10, 100 VS = +5V 80 G = 100 VS = ⴞ5V 60 40 G = 10 VS = ⴞ5V 20 1 10 100 1k FREQUENCY – Hz 10k 100k 1M Figure 1. Common-Mode Rejection vs. Frequency INPUT COMMON-MODE RANGE – V 140 COMMON-MODE REJECTION – dB 8 1/6 APPLICATIONS Current Sensing Interface for Pressure Transducers, Position Indicators, Strain Gages, and Other Low Level Signal Sources 0 0.1 200k⍀ 1 20 ⴞVCM FOR SINGLE AND DUAL SUPPLIES 15 10 ⴞVCM FOR DUAL SUPPLIES ONLY 5 0 1 2 3 SUPPLY VOLTAGE – ⴞV 4 5 Figure 2. Input Common-Mode Range vs. Supply REV. D 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. 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 companies. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 © 2003 Analog Devices, Inc. All rights reserved. AD626* PRODUCT PAGE QUICK LINKS Last Content Update: 02/24/2017 COMPARABLE PARTS REFERENCE MATERIALS View a parametric search of comparable parts. Technical Articles • Auto-Zero Amplifiers DOCUMENTATION • High-performance Adder Uses Instrumentation Amplifiers Application Notes • AN-244: A User's Guide to I.C. Instrumentation Amplifiers • Input Filter Prevents Instrumentation-amp RFRectification Errors • AN-245: Instrumentation Amplifiers Solve Unusual Design Problems • The AD8221 - Setting a New Industry Standard for Instrumentation Amplifiers • AN-282: Fundamentals of Sampled Data Systems • AN-589: Ways to Optimize the Performance of a Difference Amplifier DESIGN RESOURCES • AD626 Material Declaration • AN-671: Reducing RFI Rectification Errors in In-Amp Circuits • PCN-PDN Information Data Sheet • Symbols and Footprints • AD626: Low Cost, Single Supply Differential Amplifier Data Sheet Technical Books • A Designer's Guide to Instrumentation Amplifiers, 3rd Edition, 2006 TOOLS AND SIMULATIONS • AD626 SPICE Macro-Model • Quality And Reliability DISCUSSIONS View all AD626 EngineerZone Discussions. SAMPLE AND BUY Visit the product page to see pricing options. TECHNICAL SUPPORT Submit a technical question or find your regional support number. DOCUMENT FEEDBACK Submit feedback for this data sheet. This 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 modified. AD626–SPECIFICATIONS SINGLE SUPPLY (@+VS = +5 V and TA = 25ⴗC, unless otherwise noted.) Model Parameter GAIN Gain Accuracy Gain = 10 Gain = 100 Over Temperature, TA = TMIN to TMAX Gain Linearity Gain = 10 Gain = 100 OFFSET VOLTAGE Input Offset Voltage vs. Temperature vs. Temperature vs. Supply Voltage (PSR) +PSR –PSR Condition Min Total Error @ VOUT ≥ 100 mV dc @ VOUT ≥ 100 mV dc G = 10 G = 100 @ VOUT ≥ 100 mV dc @ VOUT ≥ 100 mV dc RL = 10 k⍀ f = 100 Hz, VCM = +24 V f = 10 kHz, VCM = +6 V f = 100 Hz, VCM = –2 V COMMON-MODE VOLTAGE RANGE +CMV Gain = 10 –CMV Gain = 10 CMR > 85 dB CMR > 85 dB Negative DYNAMIC RESPONSE –3 dB Bandwidth Slew Rate, TMIN to TMAX Settling Time POWER SUPPLY Operating Range Quiescent Current TRANSISTOR COUNT 1.0 1.0 50 150 0.2 0.5 0.6 0.6 30 120 % % ppm/°C ppm/°C 0.014 0.014 0.016 0.02 0.014 0.014 0.016 0.02 % % 1.9 2.5 2.9 6 1.9 2.5 2.9 6 mV mV µV/°C dB dB 66 55 60 90 64 85 80 55 73 90 64 85 dB dB dB +24 –2 +24 –2 V V 200 100 6 (VS – l) 200 100 6 (VS – l) k⍀ k⍀ V 4.90 4.90 V V V V 12 12 mA 2 2 0.25 0.25 2 2 0.25 0.25 µV p-p µV p-p µV/冑Hz µV/冑Hz 100 0.22 0.17 22 kHz V/µs V/µs µs 0.17 0.1 2.4 Number of Transistors Unit 80 66 f = 0.1 Hz–10 Hz f = 0.1 Hz–10 Hz f = 1 kHz f = 1 kHz TA = TMIN to TMAX Gain = 10 Gain = 100 Max 74 64 4.7 4.7 0.03 0.03 VOUT = +1 V dc Gain = 10 Gain = 100 to 0.01%, 1 V Step AD626B Typ 80 66 Short Circuit Current +ISC NOISE Voltage Noise RTI Gain = 10 Gain = 100 Gain = 10 Gain = 100 Min 74 64 INPUT Input Resistance Differential Common-Mode Input Voltage Range (Common-Mode) RL = 10 k⍀ Gain = 10 Gain = 100 Gain = 10 Gain = 100 Max 0.4 0.1 TMIN to TMAX, G = 10 or 100 TMIN to TMAX, G = 10 or 100 COMMON-MODE REJECTION +CMR Gain = 10, 100 ±CMR Gain = 10, 100 –CMR Gain = 10, 100* OUTPUT Output Voltage Swing Positive AD626A Typ 4.90 4.90 4.7 4.7 0.03 0.03 100 0.22 0.17 24 5 0.16 0.23 46 0.17 0.1 12 0.20 0.29 2.4 5 0.16 0.23 10 0.20 0.29 V mA mA 46 *At temperatures above 25°C, –CMV degrades at the rate of 12 mV/°C; i.e., @ 25°C CMV = –2 V, @ 85°C CMV = –1.28 V. Specifications subject to change without notice. –2– REV. D AD626 DUAL SUPPLY (@+VS = ⴞ5 V and TA = 25ⴗC, unless otherwise noted.) Model Parameter GAIN Gain Accuracy Gain = 10 Gain = 100 Over Temperature, TA = TMIN to TMAX Condition Min Total Error RL = 10 k⍀ TMIN to TMAX, G = 10 or 100 TMIN to TMAX, G = 10 or 100 COMMON-MODE REJECTION +CMR Gain = 10, 100 ±CMR Gain = 10, 100 RL = 10 k⍀ f = 100 Hz, VCM = +24 V f = 10 kHz, VCM = 6 V COMMON-MODE VOLTAGE RANGE +CMV Gain = 10 –CMV Gain = 10 CMR > 85 dB CMR > 85 dB RL = 10 k⍀ Gain = 10, 100 Gain = 10 Gain = 100 DYNAMIC RESPONSE –3 dB Bandwidth Slew Rate, TMIN to TMAX Settling Time POWER SUPPLY Operating Range Quiescent Current TRANSISTOR COUNT 0.1 0.15 0.3 0.6 30 80 % % ppm/°C ppm/°C 0.045 0.01 0.055 0.015 0.045 0.01 0.055 0.015 % % 50 500 1.0 50 250 0.5 0.5 µV mV µV/°C dB dB 66 55 90 60 80 55 90 60 dB dB 26.5 32.5 26.5 32.5 V V 200 110 6 (VS – l) 200 110 6 (VS – l) k⍀ k⍀ V 4.90 –2.1 –1.8 V V V 12 0.5 12 0.5 mA mA 2 2 0.25 0.25 2 2 0.25 0.25 µV p-p µV p-p µV/冑Hz µV/冑Hz 100 0.22 0.17 22 kHz V/µs V/µs µs ⫾1.2 4.90 –2.1 –1.8 –3– 4.7 –1.65 –1.45 100 0.22 0.17 24 ⫾5 1.5 1.5 46 Specifications subject to change without notice. REV. D 0.5 1.0 50 100 80 66 0.17 0.1 Number of Transistors Unit 74 64 f = 0.1 Hz–10 Hz f = 0.1 Hz–10 Hz f = 1 kHz f = 1 kHz TA = TMIN to TMAX Gain = 10 Gain = 100 Max 80 66 4.7 –1.65 –1.45 VOUT = +1 V dc Gain = 10 Gain = 100 to 0.01%, 1 V Step AD626B Typ 74 64 Short Circuit Current +ISC –ISC NOISE Voltage Noise RTI Gain = 10 Gain = 100 Gain = 10 Gain = 100 Min 1.0 INPUT Input Resistance Differential Common-Mode Input Voltage Range (Common-Mode) OUTPUT Output Voltage Swing Positive Negative Max 0.2 0.25 G = 10 G = 100 Gain Linearity Gain = 10 Gain = 100 OFFSET VOLTAGE Input Offset Voltage vs. Temperature vs. Temperature vs. Supply Voltage (PSR) +PSR –PSR AD626A Typ 0.17 0.1 ⫾6 2 2 ⫾1.2 ⫾5 1.5 1.5 46 ⫾6 2 2 V mA mA AD626 ABSOLUTE MAXIMUM RATINGS1 NOTES 1 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 8-Lead Plastic Package: ␪JA = 100°C/W; ␪JC = 50°C/W. 8-Lead SOIC Package: ␪JA = 155°C/W; ␪JC = 40°C/W. Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +36V Internal Power Dissipation2 Peak Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +60 V Maximum Reversed Supply Voltage Limit . . . . . . . . . . . . . –34V Output Short Circuit Duration . . . . . . . . . . . . . . . . . . Indefinite Storage Temperature Range (N, R) . . . . . . . . . –65°C to +125°C Operating Temperature Range AD626A/AD626B . . . . . . . . . . . . . . . . . . . . –40°C to +85°C Lead Temperature Range (Soldering 60 sec) . . . . . . . . . +300°C ORDERING GUIDE Model Temperature Range Package Description Package Option AD626AN AD626AR AD626BN AD626AR-REEL AD626AR-REEL7 –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C Plastic DIP Small Outline IC Plastic DIP 13" Tape and Reel 7" Tape and Reel N-8 R-8 N-8 METALLIZATION PHOTOGRAPH Dimensions shown in inches and (mm). CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD626 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. –4– REV. D Typical Performance Characteristics–AD626 6 VS = ⴞ5V GAIN = 10, 100 5 POSITIVE OUTPUT VOLTAGE – V INPUT COMMON-MODE RANGE – V 25 20 ⴞVCM FOR SINGLE AND DUAL SUPPLIES 15 10 ⴞVCM FOR DUAL SUPPLIES ONLY 5 0 4 3 2 1 0 –1 1 2 3 4 5 10 100 1k LOAD RESISTANCE – ⍀ SUPPLY VOLTAGE – ⴞV TPC 1. Input Common-Mode Range vs. Supply TPC 4. Positive Output Voltage Swing vs. Resistive Load –6 TA = 25ⴗC NEGATIVE OUTPUT VOLTAGE – V POSITIVE OUTPUT VOLTAGE SWING – V 5 4 SINGLE AND DUAL SUPPLY 3 2 DUAL SUPPLY ONLY 1 –5 –4 –3 GAIN = 10 –2 GAIN = 100 –1 0 0 0 1 2 3 SUPPLY VOLTAGE – V 4 1 100 5 TPC 2. Positive Output Voltage Swing vs. Supply Voltage 1k 10k LOAD RESISTANCE – ⍀ 100k TPC 5. Negative Output Voltage Swing vs. Resistive Load –5 30 TA = 25ⴗC CHANGE IN OFFSET VOLTAGE – ␮V NEGATIVE OUTPUT VOLTAGE SWING – V 10k –4 –3 DUAL SUPPLY ONLY –2 –1 0 0 1 2 3 SUPPLY VOLTAGE – V 4 20 10 0 5 0 1 2 3 4 5 WARM-UP TIME – Minutes TPC 3. Negative Output Voltage Swing vs. Supply Voltage REV. D TPC 6. Change in Input Offset Voltage vs. Warm-Up Time –5– AD626 100 COMMON-MODE REJECTION – dB 1000 VS = ⴞ5V DUAL SUPPLY CLOSED-LOOP GAIN GAIN = 100 100 VS = +5V SINGLE SUPPLY GAIN = 10 10 VS = ⴞ5V DUAL SUPPLY 0 10 100 90 85 80 VS = ⴞ5 75 70 1k 10k FREQUENCY – Hz 100k 65 20 1M TPC 7. Closed-Loop Gain vs. Frequency 22 24 26 28 INPUT COMMON-MODE VOLTAGE – V 30 TPC 10. Common-Mode Rejection vs. Input Common- Mode Voltage for Dual-Supply Operation 100 140 COMMON-MODE REJECTION – dB 120 COMMON-MODE REJECTION – dB 95 100 G = 10, 100 VS = +5 80 G = 100 VS = ⴞ5 60 40 G = 10 VS = ⴞ5 G = 10, 100 90 80 70 20 0 0.1 60 1 10 100 1k FREQUENCY – Hz 10k 100k 1M 0 TPC 8. Common-Mode Rejection vs. Frequency 60 80 0.7 G = 10, 100 95 CURVE APPLIES TO ALL SUPPLY VOLTAGES AND GAINS BETWEEN 10 AND 100 0.6 ADDITIONAL GAIN ERROR – % COMMON-MODE REJECTION – dB 40 TPC 11. Common-Mode Rejection vs. Input Source Resistance Mismatch 100 90 85 80 VS = +5 75 70 65 –5 20 INPUT SOURCE RESISTANCE MISMATCH – ⍀ 0.5 TOTAL GAIN ERROR = GAIN ACCURACY (FROM SPEC TABLE) + ADDITIONAL GAIN ERROR 0.4 0.3 0.2 0.1 0 5 10 15 20 INPUT COMMON-MODE VOLTAGE – V 0.0 25 10 TPC 9. Common-Mode Rejection vs. Input CommonMode Voltage for Single-Supply Operation 100 SOURCE RESISTANCE MISMATCH – ⍀ 1k TPC 12. Additional Gain Error vs. Source Resistance Mismatch –6– REV. D AD626 2␮V PER VERTICAL DIVISION QUIESCENT CURRENT – mA 0.16 0.15 G = 10 0.14 0.13 0.12 1 2 3 SUPPLY VOLTAGE – V 4 5 5 SECONDS PER HORIZONTAL DIVISION TPC 13. Quiescent Supply Current vs. Supply Voltage for Single-Supply Operation TPC 16. 0.1 Hz to 10 Hz RTI Voltage Noise. VS = ±5 V, Gain = 100 100 80 1.5 CLOSED-LOOP GAIN QUIESCENT CURRENT – mA 2.0 1.0 FOR VS = ⴞ5V AND +5V 60 40 0.5 20 0 ⴞ1 ⴞ2 ⴞ3 SUPPLY VOLTAGE – V ⴞ4 0 ⴞ5 1 TPC 14. Quiescent Supply Current vs. Supply Voltage for Dual-Supply Operation POWER SUPPLY REJECTION – dB Hz VOLTAGE NSD – ␮V/ 100k 1M 140 1.0 GAIN = 10, 100 0.1 VS = ⴞ5V DUAL SUPPLY 1 10 100 1k FREQUENCY – Hz 10k ALL CURVES FOR GAINS OF 10 OR 100 120 100 SINGLE AND DUAL –PSRR 80 60 SINGLE +PSRR 40 20 0.1 100k TPC 15. Noise Voltage Spectral Density vs. Frequency REV. D 100 1k 10k VALUE OF RESISTOR RG – ⍀ TPC 17. Closed-Loop Gain vs. RG 10 0.01 10 DUAL DUAL +PSRR +PSRR 1 10 100 1k FREQUENCY – Hz 10k 100k 1M TPC 18. Power Supply Rejection vs. Frequency –7– AD626 100 100 90 90 10 10 0% 0% TPC 19. Large Signal Pulse Response. VS = ±5 V, G = 10 TPC 22. Large Signal Pulse Response. VS = +5 V, G = 100 100 100 90 90 10 10 0% 0% TPC 20. Large Signal Pulse Response. VS = ±5 V, G = 100 TPC 23. Settling Time. VS = ±5 V, G = 10 500mV 100 100 90 90 10 10 0% 0% TPC 21. Large Signal Pulse Response. VS = +5 V, G = 10 TPC 24. Settling Time. VS = ±5 V, G = 100 –8– REV. D AD626 100 100 90 90 10 10 0% 0% TPC 25. Settling Time. VS = +5 V, G = 10 TPC 26. Settling Time. VS = +5 V, G = 100 Figure 4 shows the main elements of the AD626. The signal inputs at Pins 1 and 8 are first applied to dual resistive attenuators R1 through R4 whose purpose is to reduce the peak common-mode voltage at the input to the preamplifier—a feedback stage based on the very low drift op amp A1. This allows the differential input voltage to be accurately amplified in the presence of large common-mode voltages six times greater than that which can be tolerated by the actual input to A1. As a result, the input CMR extends to six times the quantity (VS – 1 V). The overall commonmode error is minimized by precise laser-trimming of R3 and R4, thus giving the AD626 a common-mode rejection ratio (CMRR) of at least 10,000:1 (80 dB). ERROR OUT 10k⍀ 10k⍀ 2k⍀ +VS INPUT 20V p–p 10k⍀ AD626 1k⍀ –VS Figure 3. Settling Time Test Circuit To minimize the effect of spurious RF signals at the inputs due to rectification at the input to A1, small filter capacitors C1 and C2 are included. THEORY OF OPERATION The AD626 is a differential amplifier consisting of a precision balanced attenuator, a very low drift preamplifier (A1), and an output buffer amplifier (A2). It has been designed so that small differential signals can be accurately amplified and filtered in the presence of large common-mode voltages (VCM), without the use of any other active components. The output of A1 is connected to the input of A2 via a 100 k⍀ (R12) resistor to facilitate the low-pass filtering of the signal of interest (see Low-Pass Filtering section). The 200 k⍀ input impedance of the AD626 requires that the source resistance driving this amplifier be low in value (