AD746

a FEATURES AC PERFORMANCE 500 ns Settling to 0.01% for 10 V Step 75 V/ s Slew Rate 0.0001% Total Harmonic Distortion (THD) 13 MHz Gain Bandwidth Internal Compensation for Gains of +2 or Greater DC PERFORMANCE 0.5 mV max Offset Voltage (AD746B) 10 V/ C max Drift (AD746B) 175 V/mV min Open Loop Gain (AD746B) 2 V p-p Noise, 0.1 Hz to 10 Hz Available in Plastic Mini-DIP, Cerdip and Surface Mount Packages Available in Tape and Reel in Accordance with EIA-481A Standard MIL-STD-883B Processing also Available Single Version: AD744 APPLICATIONS Dual Output Buffers for 12- and 14-Bit DACs Input Buffers for Precision ADCs, Wideband Preamplifiers and Low Distortion Audio Circuitry Dual Precision, 500 ns Settling, BiFET Op Amp AD746 CONNECTION DIAGRAM Plastic Mini-DIP (N) Cerdip (Q) and Plastic SOIC (R) Packages The AD746 is available in three 8-pin packages: plastic mini DIP, hermetic cerdip and surface mount (SOIC). PRODUCT HIGHLIGHTS PRODUCT DESCRIPTION The AD746 is a dual operational amplifier, consisting of two AD744 BiFET op amps on a single chip. These precision monolithic op amps offer excellent dc characteristics plus rapid settling times, high slew rates and ample bandwidths. In addition, the AD746 provides the close matching ac and dc characteristics inherent to amplifiers sharing the same monolithic die. The single pole response of the AD746 provides fast settling: 500 ns to 0.01%. This feature, combined with its high dc precision, makes it suitable for use as a buffer amplifier for 12or 14-bit DACs and ADCs. Furthermore, the AD746’s low total harmonic distortion (THD) level of 0.0001% and very close matching ac characteristics make it an ideal amplifier for many demanding audio applications. The AD746 is internally compensated for stable operation as a unity gain inverter or as a noninverting amplifier with a gain of 2 or greater. It is available in four performance grades. The AD746J is rated over the commercial temperature range of 0 to +70°C. The AD746A and AD746B are rated over the industrial temperature range of –40°C to +85°C. The AD746S is rated over the military temperature range of –55°C to +125°C and is available processed to MIL-STD-883B, Rev. C. 1. The AD746 offers exceptional dynamic response for high speed data acquisition systems. It settles to 0.01% in 500 ns and has a 100% tested minimum slew rate of 50 V/µs (AD746B). 2. Outstanding dc precision is provided by a combination of Analog Devices’ advanced processing technology, laser wafer drift trimming and well-matched ion-implanted JFETs. Input offset voltage, input bias current and input offset current are specified in the warmed-up condition and are 100% tested. 3. Differential and multichannel systems will benefit from the AD746’s very close matching of ac characteristics. Input offset voltage specs are fully tested and guaranteed to a maximum of 0.5 mV (AD746B). 4. The AD746 has very close, guaranteed matching of input bias current between its two amplifiers. 5. Unity gain stable version AD712 also available. REV. B 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703 AD746–SPECIFICATIONS Model INPUT OFFSET VOLTAGE1 Initial Offset Offset vs. Temperature vs. Supply2 (PSRR) vs. Supply (PSRR) Long Term Stability INPUT BIAS CURRENT3 Either Input Either Input @ TMAX Either Input Offset Current Offset Current @ TMAX MATCHING CHARACTERISTICS Input Offset Voltage Input Offset Voltage Input Offset Voltage Drift Input Bias Current Crosstalk FREQUENCY RESPONSE Gain BW, Small Signal Slew Rate, Unity Gain Full Power Response Settling Time to 0.01%4 Total Harmonic Distortion INPUT IMPEDANCE Differential Common Mode INPUT VOLTAGE RANGE Differential5 Common-Mode Voltage Over Max Operating Range6 Common-Mode Rejection Ratio Conditions Min TMIN to TMAX TMIN to TMAX 80 80 (@ +25 C and AD746J/A Typ 0.3 12 95 15 15 V dc, unless otherwise noted) Max 1.5 2.0 20 84 84 Min AD746B Typ 0.25 5 100 15 250 5.7/16 350 125 2.8/8 1.5 2.0 20 125 110 7 145 45 3 0.3 150 9.6 200 75 4.8 0.5 0.7 20 75 Max 0.5 0.7 10 80 80 Min AD746S Typ 0.3 12 95 15 110 113 145 45 45 0.6 250 256 350 125 128 1.0 1.5 20 125 Max Units 1.0 1.5 20 mV mV µV/°C dB dB µV/month pA nA pA pA nA mV mV µV/°C pA dB dB VCM = 0 V VCM = 0 V VCM = +10 V VCM = 0 V VCM = 0 V 110 2.5/7 145 45 1.0/3 0.6 TMIN to TMAX @ 1 kHz @ 100 kHz G = –1 8 G = –1 45 VO = 20 V p-p G=1 f = 1 kHz R1 ≥ 2 kΩ VO = 3 V rms 120 90 13 75 600 0.5 0.0001 2.5 × l01l 5.5 2.5 × l01l 5.5 ± 20 +14.5, –11.5 VCM = ± 10 V TMIN to TMAX VCM = ± 11 V TMIN to TMAX 0.1 to 10 Hz f = 10 Hz f = 100 Hz f = 1 kHz f = 10 kHz f = 1 kHz VO = ± 10 V R1 ≥ 2 kΩ 150 TMIN to TMAX 75 R1 ≥ 2 kΩ +13, –12.5 TMIN to TMAX ± 12 Short Circuit Gain = –1 Gain = –10 –11 78 76 72 70 120 90 9 50 0.75 13 75 600 0.5 0.0001 2.5 × l01l 5.5 2.5 × l01l 5.5 ± 20 +14.5, –11.5 +13 –11 82 80 78 74 +13 88 84 84 80 2 45 22 18 16 0.01 175 75 300 200 150 65 –11 78 76 72 70 8 45 0.75 120 90 13 75 600 0.5 0.0001 2.5 × l01l 5.5 2.5 × l01l 5.5 ± 20 +14.5, –11.5 +13 88 84 84 80 2 45 22 18 16 0.01 300 175 MHz V/µs kHz 0.75 µs % Ω pF Ω pF V V V dB dB dB dB µV p-p nV/ Hz nV/ Hz nV/ Hz nV/ Hz pA/ Hz V/mV V/mV V V mA pF pF V V mA °C 88 84 84 80 2 45 22 18 16 0.01 300 200 +13.9, –13.3 +13.8, –13.1 25 50 500 ± 15 INPUT VOLTAGE NOISE INPUT CURRENT NOISE OPEN LOOP GAIN OUTPUT CHARACTERISTICS Voltage Current Max Capacitive Load Driving Capability POWER SUPPLY Rated Performance Operating Range Quiescent Current TEMPERATURE RANGE Rated Performance PACKAGE OPTIONS 8-Pin Plastic Mini-DIP (N-8) 8-Pin Cerdip (Q-8) 8-Pin Surface Mount (R-8) Tape and Reel Chips TRANSISTOR COUNT +13, –12.5 +13.9, –13.3 12 +13.8, –13.1 25 50 500 ± 15 18 10 4.5 7 –40 to +85 18 8.0 +13, –12.5 +13.9, –13.3 12 +13.8, –13.1 25 50 500 ± 15 4.5 7 –55 to +125 18 10 4.5 7 0 to +70/–40 to +85 AD746JN AD746AQ AD746JR AD746JR-REEL 54 AD746BQ AD746SQ AD746SCHIPS 54 54 –2– REV. B AD746 NOTES 1 Input Offset Voltage specifications are guaranteed after 5 minutes of operation at T A = +25°C. 2 PSRR test conditions: +V S = 15 V, –V S = –12 V to –18 V and +V S = 12 V to 18 V, –V S = –15 V. 3 Bias Current Specifications are guaranteed maximum at either input after 5 minutes of operation at T A = +25 °C. For higher temperature, the current doubles every 10°C. 4 Gain = –1, Rl = 2 k, Cl = 10 pF. 5 Defined as voltage between inputs, such that neither exceeds ± 10 V from ground. 6 Typically exceeding –14.1 V negative common-mode voltage on either input results in an output phase reversal. Specifications subject to change without notice. Specifications in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and max specifications are guaranteed, although only those shown in boldface are tested on all production units. Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V Internal Power Dissipation2 . . . . . . . . . . . . . . . . . . . . . 500 mW Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± VS Output Short Circuit Duration (For One Amplifier) . . . . . . . . . . . . . . . . . . . . . . . Indefinite Differential Input Voltage . . . . . . . . . . . . . . . . . . +VS and –VS Storage Temperature Range (Q) . . . . . . . . . . –65°C to +150°C Storage Temperature Range (N, R) . . . . . . . . –65°C to +125°C Operating Temperature Range AD746J . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0°C to +70°C AD746A/B . . . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C AD746S . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C ABSOLUTE MAXIMUM RATINGS 1 Lead Temperature Range (Soldering 60 seconds) . . . . . . . . . . . . . . . . . . . . . . . +300°C ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . NOTES 1 Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and 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-Pin Plastic Package: θJA = 100°C/Watt, θJC = 50°C/Watt 8-Pin Cerdip Package: θJA = 110°C/Watt, θJC = 30°C/Watt 8-Pin Small Outline Package: θJA = 160°C/Watt, θJC = 42°C/Watt METALIZATION PHOTOGRAPH Contact factory for latest dimensions. 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 AD746 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. WARNING! ESD SENSITIVE DEVICE REV. B –3– AD746 –Typical Characteristics Figure 1. Input Voltage Swing vs. Supply Voltage Figure 2. Output Voltage Swing vs. Supply Voltage Figure 3. Output Voltage Swing vs. Load Resistance . Figure 4. Quiescent Current vs. Supply Voltage Figure 5. Input Bias Current vs. Temperature Figure 6. Output Impedance vs. Frequency Figure 7. Input Bias Current vs. Common Mode Voltage Figure 8. Short Circuit Current Limit vs. Temperature Figure 9. Gain Bandwidth Product vs. Temperature –4– REV. B AD746 Figure 10. Open Loop Gain and Phase Margin vs. Frequency Figure 11. Settling Time vs. Closed Loop Voltage Gain Figure 12. Open Loop Gain vs. Supply Voltage Figure 13. Common-Mode and Power Supply Rejection vs. Frequency Figure 14. Large Signal Frequency Response Figure 15. Output Swing and Error vs. Settling Time Figure 16. Total Harmonic Distortion vs. Frequency Using Circuit of Figure 19 Figure 17. Input Noise Voltage Spectral Density Figure 18. Slew Rate vs. Input Error Signal REV. B –5– AD746 POWER SUPPLY BYPASSING The power supply connections to the AD746 must maintain a low impedance to ground over a bandwidth of 13 MHz or more. This is especially important when driving a significant resistive or capacitive load, since all current delivered to the load comes from the power supplies. Multiple high quality bypass capacitors are recommended for each power supply line in any critical application. A 0.1 µF ceramic and a 1 µF tantalum capacitor as shown in Figure 20 placed as close as possible to the amplifier (with short lead lengths to power supply common) will assure adequate high frequency bypassing, in most applications. A minimum bypass capacitance of 0.1 µF should be used for any application. If only one of the two amplifiers inside the AD746 is to be utilized, the unused amplifier should be connected as shown in Figure 21a. Note that the noninverting input should be grounded and that RL and CL are not required. Figure 19. THD Test Circuit Figure 20. Power Supply Bypassing Figure 21a. Gain of 2 Follower Figure 21b. Gain of 2 Follower Large Signal Pulse Response Figure 21c. Gain of 2 Follower Small Signal Pulse Response Figure 22a. Unity Gain Inverter Figure 22b. Unity Gain Inverter Large Signal Pulse Response Figure 22c. Unity Gain Inverter Small Signal Pulse Response –6– REV. B AD746 A HIGH SPEED 3 OR AMP INSTRUMENTATION AMPLIFIER CIRCUIT Table I. Performance Summary for the 3 Op Amp Instrumentation Amplifier Circuit The instrumentation amplifier circuit shown in Figure 23 can provide a range of gains from 2 up to 1000 and higher. The circuit bandwidth is 2.5 MHz at a gain of 2 and 750 kHz at a gain of 10; settling time for the entire circuit is less than 2 µs to within 0.01% for a 10 volt step, (G = 10). Gain 2 10 100 RG 20 kΩ 4.04 kΩ 404 Ω Bandwidth 2.5 MHz 1 MHz 290 kHz TSETTLE (0.01%) 1.0 µs 2.0 µs 5.0 µs Figure 25. Settling Time of the 3 Op Amp Instrumentation Amplifier. Gain = 10, Horizontal Scale: 0.5 µ s/Div, Vertical Scale: 5 V/Div. Error Signal Scale: 0.01%/Div. THD Performance Considerations Figure 23. A High Performance, 3 Op Amp, Instrumentation Amplifier Circuit The AD746 was carefully optimized to offer excellent performance in terms of total harmonic distortion (THD) in signal processing applications. The THD level when operating the AD746 in inverting gain applications will show a gradual rise from the distortion floor of 20 dB/decade (see Figure 28). In noninverting applications, care should be taken to balance the source impedances at both the inverting and noninverting inputs, to avoid distortion caused by the modulation of input capacitance inherent in all BiFET op amps. Figure 26. THD Measurement, Inverter Circuit Figure 24. Pulse Response of the 3 Op Amp Instrumentation Amplifier. Gain = 10, Horizontal Scale: 0.5 µ s/Div, Vertical Scale: 5 V/Div. Figure 27. THD Measurement, Follower Circuit REV. B –7– AD746 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Mini-DIP (N) Package Figure 28. THD vs. Frequency Using Standard Distortion Analyzer 2kΩ Cerdip (Q) Package 2kΩ 2– SINE WAVE GENERATOR 20V p-p OUTPUT LEVEL 1/2 AD746 4 –VS 1µF + VOUT #1 1 20V p-p 3+ 0.1µF 20kΩ 2.21kΩ 6– +VS 1µF 7 + 0.1µF 1/2 8 AD746 VOUT #2 5+ CROSSTALK = 20 LOG10 VOUT #1 + 20dB VOUT #2 Figure 29. Crosstalk Test Circuit Plastic Small Outline (R) Package Figure 30. Crosstalk vs. Frequency –8– REV. B PRINTED IN U.S.A. C1319–10–9/89