a Precision Micropower Single-Supply Operational Amplifiers OP777/OP727/OP747 FEATURES Low Offset Voltage: 100 V Max Low Input Bias Current: 10 nA Max Single-Supply Operation: 2.7 V to 30 V Dual-Supply Operation: 1.35 V to 15 V Low Supply Current: 300 A/Amp Max Unity Gain Stable No Phase Reversal FUNCTIONAL BLOCK DIAGRAMS 14-Lead SOIC (R-14) 8-Lead MSOP (RM-8) 1 NC IN IN V 8 NC V+ OUT NC OP777 4 5 NC = NO CONNECT APPLICATIONS Current Sensing (Shunt) Line or Battery-Powered Instrumentation Remote Sensors Precision Filters OP727 SOIC Pin-Compatible with LT1013 GENERAL DESCRIPTION The OP777 , OP727 , and OP747 are precision single , dual, and quad rail-to-rail output single- supply amplifiers featuring micropower operation and rail-to-rail output ranges. These amplifier s provide improved performance over the industry -standard OP07 with ± 15 V supplies , and offer the further advantage of true single -supply operation down to 2.7 V , and smaller package options than any other high-voltage precision bipolar amplifier. Outputs are stable with capacitive loads of over 500 pF. Supply current is less than 300 µA per amplifier at 5 V. 500 Ω series resistors protect the inputs, allowing input signal levels several volts above the positive supply without phase reversal. Applications for these amplifiers include both line-powered and portable instrumentation, remote sensor signal conditioning, and precision filters. The OP777, OP727, and OP747 are specified over the extended industrial (–40°C to +85°C) temperature range. The OP777, single, is available in 8-lead MSOP and 8-lead SOIC packages. The OP747, quad, is available in 14-lead TSSOP and narrow 14-lead SO packages. Surface-mount devices in TSSOP and MSOP packages are available in tape and reel only. The OP727, dual, is available in 8-lead TSSOP and 8-lead SOIC packages. The OP727 8-lead SOIC pin configuration differs from the standard 8-lead operational amplifier pinout. OUT A 1 14 OUT D –IN A 2 13 –IN D IN A 3 12 IN D V 4 V– TOP VIEW (Not to Scale) 10 IN B 5 IN C 8-Lead SOIC (R-8) NC 1 IN 2 OP777 –IN B 6 9 –IN C OUT B 7 8 OUT C 14-Lead TSSOP (RU-14) 7 V+ 6 OUT V 4 5 NC NC = NO CONNECT 8-Lead TSSOP (RU-8) 8 14 OUT D –IN A 2 13 –IN D IN A 3 12 IN D OP747 TOP VIEW 11 V– (Not to Scale) 10 IN B 5 IN C –IN B 6 9 –IN C 7 8 OUT C V OUT B 7 OUT B OP727 TOP VIEW IN A 3 (Not to Scale) 6 –IN B 5 OUT A 1 V 4 –IN A 2 V– 4 11 8 NC +IN 3 OUT A 1 OP747 IN B 8-Lead SOIC (R-8) IN A 1 8 OP727 –IN A OUT A TOP VIEW IN B 3 (Not to Scale) 6 V V– 2 –IN B 4 7 5 OUT B NOTE: THIS PIN CONFIGURATION DIFFERS FROM THE STANDARD 8-LEAD OPERATIONAL AMPLIFIER PINOUT. REV. C 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. 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 © Analog Devices, Inc., 2001 OP777/OP727/OP747–SPECIFICATIONS ELECTRICAL CHARACTERISTICS (@ V = 5.0 V, V S CM = 2.5 V, TA = 25C unless otherwise noted.) Parameter Symbol Conditions INPUT CHARACTERISTICS Offset Voltage OP777 VOS IB IOS +25 C < T A < +85 C –40°C < T A < +85 °C +25 C < T A < +85 C –40°C < T A < +85 °C –40°C < T A < +85 °C –40°C < T A < +85 °C CMRR AVO ∆VOS/∆T ∆VOS/∆T VCM = 0 V to 4 V RL = 10 k Ω , VO = 0.5 V to 4.5 V –40°C < T A < +85 °C –40°C < T A < +85 °C OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit VOH VOL IOUT IL = 1 mA, –40 °C to +85 °C IL = 1 mA, –40 °C to +85 °C VDROPOUT < 1 V 4.88 POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777 PSRR ISY VS = 3 V to 30 V VO = 0 V –40°C < T A < +85 °C VO = 0 V –40°C < T A < +85 °C 120 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product SR GBP RL = 2 k Ω 0.2 0.7 V/µs MHz NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density enp-p en in 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 0.4 15 0.13 µV p-p nV/√Hz pA/√Hz Offset Voltage OP727/OP747 Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP777 Offset Voltage Drift OP727/OP747 Supply Current/Amplifier OP727/OP747 Min 0 104 300 Typ Max Unit 20 50 30 60 5.5 0.1 100 200 160 300 11 2 4 µV µV µV µV nA nA V dB V/mV µV/°C µV/°C 110 500 0.3 0.4 4.91 126 ±10 130 220 270 235 290 1.3 1.5 140 V mV mA 270 320 290 350 dB µA µA µA µA NOTES Typical specifications: >50% of units perform equal to or better than the “typical” value. Specifications subject to change without notice. –2– REV. C OP777/OP727/OP747 ELECTRICAL CHARACTERISTICS (@ 15 V, V CM = 0 V, TA = 25C unless otherwise noted.) Parameter Symbol Conditions INPUT CHARACTERISTICS Offset Voltage OP777 VOS Offset Voltage OP727/OP747 VOS Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP777 Offset Voltage Drift OP727/OP747 IB IOS +25 °C < T A < +85 °C –40°C < T A < +85 °C +25 °C < T A < +85 °C –40°C < T A < +85 °C –40°C < T A < +85 °C –40°C < T A < +85 °C CMRR AVO ∆VOS/∆T ∆VOS/∆T VCM = –15 V to +14 V RL = 10 k Ω , V O = –14.5 V to +14.5 V –40°C < T A < +85 °C –40°C < T A < +85 °C OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Circuit VOH VOL IOUT IL = 1 mA, –40 °C to +85 °C IL = 1 mA, –40 °C to +85 °C +14.9 +14.94 –14.94 –14.9 ±30 V V mA POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier OP777 PSRR ISY VS = ± 1.5 V to ± 15 V VO = 0 V –40°C < T A < +85 °C VO = 0 V –40°C < T A < +85 °C 120 130 300 350 320 375 dB µA µA µA µA DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product SR GBP RL = 2 k Ω 0.2 0.7 V/µs MHz NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density enp-p en in 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 0.4 15 0.13 µV p-p nV/√Hz pA/√Hz Supply Current/Amplifier OP727/747 Specifications subject to change without notice. REV. C –3– Min –15 110 1,000 Typ Max Unit 30 50 30 50 5 0.1 100 200 160 300 10 2 +14 µV µV µV µV nA nA V dB V/mV µV/°C µV/°C 120 2,500 0.3 0.4 1.3 1.5 350 400 375 450 OP777/OP727/OP747 ABSOLUTE MAXIMUM RATINGS 1, 2 Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V Input Voltage . . . . . . . . . . . . . . . . . . . . –VS – 5 V to +VS + 5 V Differential Input Voltage . . . . . . . . . . . . . . ± Supply Voltage Output Short-Circuit Duration to GND . . . . . . . . . Indefinite Storage Temperature Range RM, R, RU Packages . . . . . . . . . . . . . . . . –65°C to +150°C Operating Temperature Range OP777/OP727/OP747 . . . . . . . . . . . . . . . –40°C to +85°C Junction Temperature Range RM, R, RU Packages . . . . . . . . . . . . . . . . –65°C to +150°C Lead Temperature Range (Soldering, 60 sec) . . . . . . . 300°C Electrostatic Discharge (Human Body Model) . . . . 2000 V max Package Type JA3 JC Unit 8-Lead MSOP (RM) 8-Lead SOIC (R) 8-Lead TSSOP (RU) 14-Lead SOIC (R) 14-Lead TSSOP (RU) 190 158 240 120 180 44 43 43 36 35 °C/W °C/W °C/W °C/W °C/W NOTES 1 Absolute maximum ratings apply at 25°C, unless otherwise noted. 2 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 listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 3 θJA is specified for worst-case conditions, i.e., θJA is specified for device soldered in circuit board for surface-mount packages. ORDERING GUIDE Model Temperature Range Package Description Package Option Branding Information OP777ARM OP777AR OP727ARU OP727AR OP747AR OP747ARU –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 –40°C to +85 °C 8-Lead MSOP 8-Lead SOIC 8-Lead TSSOP 8-Lead SOIC 14-Lead SOIC 14-Lead TSSOP RM-8 SO-8 RU-8 SO-8 R-14 RU-14 A1A 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 OP777/OP727/OP747 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– WARNING! ESD SENSITIVE DEVICE REV. C Typical Performance Characteristics– OP777/OP727/OP747 NUMBER OF AMPLIFIERS 180 160 140 120 100 80 60 VSY = 5V VCM = 2.5V TA = 25C 200 180 160 140 120 100 80 60 40 40 20 20 0 100 8060 4020 0 20 40 60 80 100 OFFSET VOLTAGE – V 0 100 8060 4020 0 20 40 60 80 100 OFFSET VOLTAGE – V TPC 1. OP777 Input Offset Voltage Distribution TPC 2. OP777 Input Offset Voltage Distribution VSY = 15V VCM = 0V TA = –40C TO +85C 140 120 100 80 60 VSY = 15V VCM = 0V TA = 25C 500 QUANTITY – Amplifiers QUANTITY – Amplifiers 160 40 20 15 10 5 600 200 180 VSY = 15V VCM = 0V TA = 40C TO +85C 25 NUMBER OF AMPLIFIERS 200 30 220 400 300 200 0 0 0.2 0.4 0.6 0.8 1.0 INPUT OFFSET DRIFT – V/C 1.2 TPC 3. OP777 Input Offset Voltage Drift Distribution 600 VSY = 5V VCM = 2.5V TA = 25C 500 NUMBER OF AMPLIFIERS VSY = 15V VCM = 0V TA = 25C NUMBER OF AMPLIFIERS 220 400 300 200 100 100 20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 TCVOS – V/C TPC 4. OP727/OP747 Input Offset Voltage Drift (TCVOS Distribution) 300 200 80 120 TPC 7. OP727 Input Offset Voltage Distribution 0 –120 120 –80 –40 0 40 80 120 OFFSET VOLTAGE – V TPC 6. OP747 Input Offset Voltage Distribution 30 400 300 200 100 100 0 140 120 80 40 0 40 80 OFFSET VOLTAGE – V 40 VSY = 15V VCM = 0V TA = 25C 500 NUMBER OF AMPLIFIERS NUMBER OF AMPLIFIERS 0 V 600 VSY = 5V VCM = 2.5V TA = 25C 400 REV. C –40 TPC 5. OP747 Input Offset Voltage Distribution 600 500 –80 VSY = 15V VCM = 0V TA = 25C 25 NUMBER OF AMPLIFIERS 0 –120 0 20 15 10 5 0 0 40 140 120 80 40 80 OFFSET VOLTAGE – V 120 TPC 8. OP727 Input Offset Voltage Distribution –5– 0 3 5 7 4 6 INPUT BIAS CURRENT – nA TPC 9. Input Bias Current Distribution 8 OP777/OP727/OP747 VS = 5V TA = 25C 1.0 0.1 100 10 SINK 1.0 SOURCE 0 0.001 100 0.1 1 10 LOAD CURRENT – mA TPC 10. Output Voltage to Supply Rail vs. Load Current 140 ISY+ (VSY = 5V) 100 0 100 200 ISY (VSY = 5V) 300 250 200 150 100 50 ISY (VSY = 15V) 400 100 OPEN-LOOP GAIN – dB SUPPLY CURRENT – A SUPPLY CURRENT – A 200 500 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C 0 TPC 13. Supply Current vs. Temperature 0 5 10 15 20 25 SUPPLY VOLTAGE – V 60 VSY = 5V CLOAD = 0 RLOAD = 80 0 60 45 40 90 20 135 0 180 –20 225 –40 270 1k 10k 100k 1M FREQUENCY – Hz 10M 100M TPC 16. Open Loop Gain and Phase Shift vs. Frequency CLOSED-LOOP GAIN – dB 100 0 45 40 90 20 135 0 180 –20 225 –40 270 –60 10 35 30 40 AV = 100 30 20 10 AV = 10 0 10 AV = +1 20 30 40 1k 100 1k 10k 100k 1M 10M 100M FREQUENCY – Hz TPC 15. Open Loop Gain and Phase Shift vs. Frequency 60 VSY = 15V CLOAD = 0 RLOAD = 2k 50 PHASE SHIFT – Degrees 120 80 60 TPC 14. Supply Current vs. Supply Voltage 140 VSY = 15V CLOAD = 0 RLOAD = 120 300 ISY+ (VSY = 15V) 2 TPC 12. Input Bias Current vs. Temperature TA = 25C 300 3 0 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C 100 350 400 OPEN-LOOP GAIN – dB 0.1 1 10 LOAD CURRENT – mA 0.01 TPC 11. Output Voltage to Supply Rail vs. Load Current 500 4 1 0.1 0.01 5 PHASE SHIFT – Degrees SOURCE 10 INPUT BIAS CURRENT – nA SINK 100 –60 100 VSY = 15V 1k OUTPUT VOLTAGE – mV OUTPUT VOLTAGE – mV 1k 0 0.001 6 10k VS = 15V TA = 25C VSY = 5V CLOAD = 0 RLOAD = 2k 50 CLOSED-LOOP GAIN – dB 10k 40 AV = 100 30 20 10 AV = 10 0 10 AV = +1 20 30 10k 100k 1M 10M FREQUENCY – Hz 100M TPC 17. Closed Loop Gain vs. Frequency –6– 40 1k 10k 100k 1M 10M FREQUENCY – Hz 100M TPC 18. Closed Loop Gain vs. Frequency REV. C OP777/OP727/OP747 240 210 180 150 120 90 60 AV = 100 AV = 10 240 210 AV = 1 180 150 120 90 60 30 0V AV = 100 AV = 10 100k 10k 1M FREQUENCY – Hz 10M 0 100 100M TPC 21. Large Signal Transient Response VSY = 15V CL = 300pF RL = 2k VIN = 100mV AV = 1 20 OS 15 10 5 SMALL SIGNAL OVERSHOOT – % OS 25 TIME – 10s/DIV TPC 23. Small Signal Transient Response 35 VSY = 2.5V RL = 2k VIN = 100mV 30 TIME – 100s/DIV TIME – 10s/DIV TPC 22. Large Signal Transient Response 35 100M AV = 1 TIME – 100s/DIV 40 10M VSY = 2.5V CL = 300pF RL = 2k VIN = 100mV VOLTAGE – 50mV/DIV 0V 10k 1M 100k FREQUENCY – Hz TPC 20. Output Impedance vs. Frequency VSY = 15V RL = 2k CL = 300pF AV = 1 1k VOLTAGE – 50mV/DIV 1k TPC 19. Output Impedance vs. Frequency VOLTAGE – 1V/DIV AV = 1 30 0 100 SMALL SIGNAL OVERSHOOT – % VSY = 2.5V RL = 2k CL = 300pF VSY = 15V 270 AV = 1 OUTPUT IMPEDANCE – OUTPUT IMPEDANCE – 300 VSY = 5V 270 VOLTAGE – 1V/DIV 300 VSY = 15V RL = 2k VIN = 100mV 30 TPC 24. Small Signal Transient Response INPUT +200mV 0V 25 VSY = 15V RL = 10k AV = 100 VIN = 200mV +OS 20 OS 15 0V 10 10V 5 OUTPUT 0 1 100 10 CAPACITANCE – pF 1k TPC 25. Small Signal Overshoot vs. Load Capacitance REV. C 0 1 10 100 1k CAPACITANCE – pF 10k TPC 26. Small Signal Overshoot vs. Load Capacitance –7– TIME – 40s/DIV TPC 27. Negative Overvoltage Recovery OP777/OP727/OP747 200mV INPUT INPUT 0V INPUT 0V 0V VSY = 15V RL = 10k AV = 100 VIN = 200mV 200mV 10V VSY = 2.5V RL = 10k AV = 100 VIN = 200mV 0V OUTPUT 2V 2V 0V 0V OUTPUT TIME – 40s/DIV OUTPUT TIME – 40s/DIV TPC 29. Negative Overvoltage Recovery TPC 30. Positive Overvoltage Recovery 140 140 VS = 15V AV = 1 VOLTAGE – 5V/DIV TIME – 40s/DIV VSY = 2.5V CMRR – dB OUTPUT 120 100 100 80 60 80 60 40 40 20 20 0 TIME – 400s/DIV TPC 31. No Phase Reversal VSY = 15V 120 CMRR – dB TPC 28. Positive Overvoltage Recovery INPUT VSY = 2.5V RL = 10k AV = 100 VIN = 200mV 200mV 10 100 10k 100k 1k FREQUENCY – Hz 1M 0 10M TPC 32. CMRR vs. Frequency 140 10 100 10k 100k 1k FREQUENCY – Hz 1M 10M TPC 33. CMRR vs. Frequency 140 VSY = 2.5V VSY = 5V GAIN = 10M VSY = 15V 120 120 +PSRR 80 60 +PSRR 80 PSRR 60 40 40 20 20 0 10 100 10k 100k 1k FREQUENCY – Hz 1M TPC 34. PSRR vs. Frequency 10M VOLTAGE – 1V/DIV 100 PSRR PSRR – dB PSRR – dB 100 0 10 100 10k 100k 1k FREQUENCY – Hz 1M TPC 35. PSRR vs. Frequency –8– 10M TIME – 1s/DIV TPC 36. 0.1 Hz to 10 Hz Input Voltage Noise REV. C OP777/OP727/OP747 90 90 VSY = 15V VSY = 2.5V VOLTAGE NOISE DENSITY – nV/ Hz VOLTAGE – 1V/DIV VOLTAGE NOISE DENSITY – nV/ Hz VSY = 15V GAIN = 10M 80 70 60 50 40 30 20 80 70 60 50 40 30 20 10 0 200 300 FREQUENCY – Hz 400 40 40 30 25 20 15 10 5 35 30 25 20 15 10 5 500 1k 1.5k FREQUENCY – Hz 2.0k 0 2.5k TPC 40. Voltage Noise Density 50 20 ISC 10 0 10 20 30 40 ISC+ 50 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C TPC 43. Short Circuit Current vs. Temperature REV. C 500 VSY = 5V 40 30 20 ISC 10 0 10 20 ISC+ 30 1k 1.5k FREQUENCY – Hz 2.0k 2.5k 50 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C TPC 42. Short Circuit Current vs. Temperature 160 4.95 VSY = 5V IL = 1mA OUTPUT VOLTAGE HIGH – V 30 500 TPC 41. Voltage Noise Density VSY = 15V 40 400 40 0 0 200 300 FREQUENCY – Hz 50 VSY = 2.5V SHORT CIRCUIT CURRENT – mA 35 100 TPC 39. Voltage Noise Density 4.94 4.93 4.92 4.91 4.90 150 OUTPUT VOLTAGE LOW – mV VSY = 15V 0 500 TPC 38. Voltage Noise Density 0 SHORT CIRCUIT CURRENT – mA 10 100 TPC 37. 0.1 Hz to 10 Hz Input Voltage Noise VOLTAGE NOISE DENSITY – nV/ Hz VOLTAGE NOISE DENSITY – nV/ Hz TIME – 1s/DIV VSY = 5V IL = 1mA 140 130 120 110 100 90 80 4.89 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C TPC 44. Output Voltage High vs. Temperature –9– 70 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C TPC 45. Output Voltage Low vs. Temperature OP777/OP727/OP747 14.960 14.958 14.956 14.954 14.952 14.950 14.948 14.935 1.5 VSY = 15V IL = 1mA VSY = 15V VCM = 0V TA = 25C 1.0 14.940 0.5 VOS – V OUTPUT VOLTAGE HIGH – V 14.962 14.930 VSY = 15V IL = 1mA OUTPUT VOLTAGE LOW – V 14.964 14.945 0 14.950 0.5 14.955 1.0 14.960 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C 1.5 14.946 14.944 60 40 20 0 20 40 60 80 100 120 140 TEMPERATURE – C TPC 46. Output Voltage High vs. Temperature 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TIME – Minutes TPC 48. Warm-Up Drift TPC 47. Output Voltage Low vs. Temperature The OP777/OP727/OP747 amplifier uses a precision Bipolar PNP input stage coupled with a high-voltage CMOS output stage. This enables this amplifier to feature an input voltage range which includes the negative supply voltage (often groundin single-supply applications) and also swing to within 1 mV of the output rails. Additionally, the input voltage range extends to within 1 V of the positive supply rail. The epitaxial PNP input structure provides high breakdown voltage, high gain, and an input bias current figure comparable to that obtained with a “Darlington” input stage amplifier but without the drawbacks (i.e., severe penalties for input voltage range, offset, drift and noise). The PNP input structure also greatly lowers the noise and reduces the dc input error terms. Supply Voltage VOLTAGE – 100V/DIV BASIC OPERATION VOUT 0V VIN TIME – 0.2ms/DIV Figure 1. Input and Output Signals with VCM < 0 V The amplifiers are fully specified with a single 5 V supply and, due to design and process innovations, can also operate with a supply voltage from 2.7 V up to 30 V. This allows operation from most split supplies used in current industry practice, with the advantage of substantially increased input and output voltage ranges over conventional split-supply amplifiers. The OP777/OP727/OP747 series is specified with (VSY = 5 V, V– = 0 V and VCM = 2.5 V which is most suitable for single-supply application. With PSRR of 130 dB (0.3 µV/V) and CMRR of 110 dB (3 µV/V) offset is minimally affected by power supply or common-mode voltages. Dual supply, ±15 V operation is also fully specified. 100k 100k +3V 0.27V 100k 100k 0.1V OP777/ OP727/ OP747 VIN = 1kHz at 400mV p-p Input Common-Mode Voltage Range The OP777/OP727/OP747 is rated with an input common-mode voltage which extends from the minus supply to within 1 V of the positive supply. However, the amplifier can still operate with input voltages slightly below VEE. In Figure 2, OP777/OP727/OP747 is configured as a difference amplifier with a single supply of 2.7 V and negative dc common-mode voltages applied at the inputs terminals. A 400 mV p-p input is then applied to the noninverting input. It can be seen from the graph below that the output does not show any distortion. Micropower operation is maintained by using large input and feedback resistors. –10– Figure 2. OP777/OP727/OP747 Configured as a Difference Amplifier Operating at VCM < 0 V REV. C OP777/OP727/OP747 Input Over Voltage Protection 30V OP777/ OP727/ OP747 V p-p = 32V VOUT TIME – 400s/DIV Figure 4. No Phase Reversal Output Stage The CMOS output stage has excellent (and fairly symmetric) output drive and with light loads can actually swing to within 1 mV of both supply rails. This is considerably better than similar amplifiers featuring (so-called) rail-to-rail bipolar output stages. OP777/ OP727/OP747 is stable in the voltage follower configuration and responds to signals as low as 1 mV above ground in single supply operation. 2.7V TO 30V Figure 3a. Unity Gain Follower VOUT = 1mV VSY = 15V VOLTAGE – 5V/DIV VIN VSY = 15V VIN VOLTAGE – 5V/DIV When the input of an amplifier is more than a diode drop below VEE, or above V CC, large currents will flow from the substrate (V–) or the positive supply (V+), respectively, to the input pins which can destroy the device. In the case of OP777/OP727/ OP747, differential voltages equal to the supply voltage will not cause any problem (see Figure 3). OP777/OP727/OP747 has built- in 500 Ω internal current limiting resistors, in series with the inputs, to minimize the chances of damage. It is a good practice to keep the current flowing into the inputs below 5 mA. In this context it should also be noted that the high breakdown of the input transistors removes the necessity for clamp diodes between the inputs of the amplifier, a feature that is mandatory on many precision op amps. Unfortunately, such clamp diodes greatly interfere with many application circuits such as precision rectifiers and comparators. The OP777/OP727/OP747 series is free from such limitations. VIN = 1mV VOUT OP777/ OP727/ OP747 VOLTAGE – 25mV/DIV Figure 5. Follower Circuit TIME – 400s/DIV Figure 3b. Input Voltage Can Exceed the Supply Voltage Without Damage 1.0mV Phase Reversal Many amplifiers misbehave when one or both of the inputs are forced beyond the input common-mode voltage range. Phase reversal is typified by the transfer function of the amplifier effectively reversing its transfer polarity. In some cases this can cause lockup in servo systems and may cause permanent damage or nonrecoverable parameter shifts to the amplifier. Many amplifiers feature compensation circuitry to combat these effects, but some are only effective for the inverting input. Additionally, many of these schemes only work for a few hundred millivolts or so beyond the supply rails. OP777/ OP727/OP747 has a protection circuit against phase reversal when one or both inputs are forced beyond their input commonmode voltage range. It is not recommended that the parts be continuously driven more than 3 V beyond the rails. REV. C TIME – 10s/DIV Figure 6. Rail-to-Rail Operation Output Short Circuit The output of the OP777/OP727/OP747 series amplifier is protected from damage against accidental shorts to either supply voltage, provided that the maximum die temperature is not exceeded on a long-term basis (see Absolute Maximum Rating section). Current of up to 30 mA does not cause any damage. A Low-Side Current Monitor In the design of power supply control circuits, a great deal of design effort is focused on ensuring a pass transistor’s long-term reliability over a wide range of load current conditions. As a result, monitoring –11– OP777/OP727/OP747 and limiting device power dissipation is of prime importance in these designs. Figure 7 shows an example of 5 V, single-supply current monitor that can be incorporated into the design of a voltage regulator with foldback current limiting or a high current power supply with crowbar protection. The design capitalizes on the OP777’s common-mode range that extends to ground. Current is monitored in the power supply return where a 0.1 Ω shunt resistor, RSENSE, creates a very small voltage drop. The voltage at the inverting terminal becomes equal to the voltage at the noninverting terminal through the feedback of Q1, which is a 2N2222 or equivalent NPN transistor. This makes the voltage drop across R1 equal to the voltage drop across RSENSE. Therefore, the current through Q1 becomes directly proportional to the current through RSENSE, and the output voltage is given by: VOUT 15V 1k REF 192 2N2222 1/4 OP747 R2 12k 4 3 20k +15V R1 R1 R(1+) R +15V VO 1/4 OP747 15V R2 V R1 REF R = R VO = 1/4 OP747 15V Figure 9. Linear Response Bridge R2 = 5V − × RSENSE × I L R1 The voltage drop across R2 increases with IL increasing, so VOUT decreases with higher supply current being sensed. For the element values shown, the VOUT is 2.5 V for return current of 1 A. A single-supply current source is shown in Figure 10 . Large resistors are used to maintain micropower operation. Output current can be adjusted by changing the R2B resistor. Compliance voltage is: VL ≤ VSAT − VS 10pF 2.7V TO 30V 5V 100k R2 = 2.49k 100k VOUT OP777 R1 = 100k Q1 R2B 2.7k 5V 10pF OP777 R1 = 100 0.1 IO = RETURN TO GROUND RSENSE IO R2 = R2A + R2B R2 V R1 R2B S R2A 97.3k + VL RLOAD = 1mA 11mA Figure 7. A Low-Side Load Current Monitor Figure 10. Single-Supply Current Source The OP777/OP727/OP747 is very useful in many bridge applications. Figure 8 shows a single-supply bridge circuit in which its output is linearly proportional to the fractional deviation () of the bridge. Note that = ∆R/R. A single-supply instrumentation amplifier using one OP727 amplifier is shown in Figure 11. For true difference R3/R4 = R1/R2. The formula for the CMRR of the circuit at dc is CMRR = 20 × log (100/(1–(R2 × R3)/(R1× R4)). It is common to specify t he accuracy of the resistor network in terms of resistor-to-resistor percentage mismatch. We can rewrite the CMRR equation to reflect this CMRR = 20 × log (10000/% Mismatch). The key to high CMRR is a network of resistors that are well matched from the perspective of both resistive ratio and relative drift. It should be noted that the absolute value of the resistors and their absolute drift are of no consequence. Matching is the key. CMRR is 100 dB with 0.1% mismatched resistor network. To maximize CMRR, one of the resistors such as R4 should be trimmed. Tighter matching of two op amps in one package (OP727) offers a significant boost in performance over the triple op amp configuration. = 300 AR1VREF 15V VO = 2R2 R1 = R1 RG = 10k 2 1/4 OP747 6 REF 192 2 1M 2.5V 4 REF 192 4 + 2.5V 10.1k 3 1M 0.1F 15V 15V 3 R1 R1(1+) V1 10.1k VO 1/4 OP747 R1(1+) 1/4 OP747 R1 R3 = 10.1k R2 = 1M R2 2.7V TO 30V V2 2.7V TO 30V R4 = 1M R1 = 10.1k Figure 8. Linear Response Bridge, Single Supply VO 1/2 OP727 In systems where dual supplies are available, the circuit of Figure 9 could be used to detect bridge outputs that are linearly related to the fractional deviation of the bridge. 1/2 OP727 V1 V2 VO = 100 (V2 V1) 0.02mV V1 V2 2mV VOUT 29V 290mV USE MATCHED RESISTORS Figure 11. Single-Supply Micropower Instrumentation Amplifier –12– REV. C OP777/OP727/OP747 OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 8-Lead MSOP (RM-8) 0.122 (3.10) 0.114 (2.90) 8 5 0.122 (3.10) 0.114 (2.90) 0.199 (5.05) 0.187 (4.75) 1 4 PIN 1 0.0256 (0.65) BSC 0.120 (3.05) 0.112 (2.84) 0.120 (3.05) 0.112 (2.84) 0.043 (1.09) 0.037 (0.94) 0.006 (0.15) 0.002 (0.05) 0.018 (0.46) SEATING 0.008 (0.20) PLANE 0.011 (0.28) 0.003 (0.08) 33 27 0.028 (0.71) 0.016 (0.41) 8-Lead SOIC (R-8) 0.1968 (5.00) 0.1890 (4.80) 0.1574 (4.00) 0.1497 (3.80) 8 5 1 4 0.2440 (6.20) 0.2284 (5.80) PIN 1 0.0196 (0.50) 45 0.0099 (0.25) 0.0500 (1.27) BSC 0.0688 (1.75) 0.0532 (1.35) 0.0098 (0.25) 0.0040 (0.10) 8 0.0500 (1.27) 0.0098 (0.25) 0 0.0160 (0.41) 0.0075 (0.19) 0.0192 (0.49) 0.0138 (0.35) SEATING PLANE 8-Lead TSSOP (RU-8) 0.122 (3.10) 0.114 (2.90) 8 5 0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25) 1 4 PIN 1 0.0256 (0.65) BSC 0.006 (0.15) 0.002 (0.05) SEATING PLANE REV. C 0.0118 (0.30) 0.0075 (0.19) 0.0433 (1.10) MAX 0.0079 (0.20) 0.0035 (0.090) –13– 8 0 0.028 (0.70) 0.020 (0.50) OP777/OP727/OP747 14-Lead SOIC (R-14) 0.3444 (8.75) 0.3367 (8.55) 0.1574 (4.00) 0.1497 (3.80) 14 8 1 7 0.050 (1.27) BSC 0.0688 (1.75) 0.0532 (1.35) PIN 1 0.0098 (0.25) 0.0040 (0.10) 0.2440 (6.20) 0.2284 (5.80) 0.0196 (0.50) 45 0.0099 (0.25) 8 0 0.0500 (1.27) 0.0192 (0.49) SEATING 0.0099 (0.25) PLANE 0.0138 (0.35) 0.0160 (0.41) 0.0075 (0.19) 14-Lead TSSOP (RU-14) 0.201 (5.10) 0.193 (4.90) 14 8 0.177 (4.50) 0.169 (4.30) 0.256 (6.50) 0.246 (6.25) 1 7 PIN 1 0.006 (0.15) 0.002 (0.05) SEATING PLANE 0.0256 (0.65) BSC 0.0433 (1.10) MAX 0.0118 (0.30) 0.0075 (0.19) 0.0079 (0.20) 0.0035 (0.090) –14– 8 0 0.028 (0.70) 0.020 (0.50) REV. C OP777/OP727/OP747 Revision History Location Page Data Sheet changed from REV. B to REV. C. Addition of text to APPLICATIONS section Addition of 8-Lead SOIC (R-8) package ............................................................... 1 .................................................................. 1 Addition of text to GENERAL DESCRIPTION Addition of package to ORDERING GUIDE REV. C ............................................................. 1 ............................................................... 2 –15– –16– PRINTED IN U.S.A. CO2051–0–9/01(C)