OP4177ARU

Precision Low Noise, Low Input Bias Current Operational Amplifiers OP1177/OP2177/OP4177 FEATURES Low offset voltage: 60 μV maximum Very low offset voltage drift: 0.7 μV/°C maximum Low input bias current: 2 nA maximum Low noise: 8 nV/√Hz typical CMRR, PSRR, and AVO > 120 dB minimum Low supply current: 400 μA per amplifier Dual supply operation: ±2.5 V to ±15 V Unity-gain stable No phase reversal Inputs internally protected beyond supply voltage PIN CONFIGURATIONS NC 1 8 NC –IN 2 +IN 3 02627-001 4 5 NC = NO CONNECT NC = NO CONNECT Figure 1. 8-Lead MSOP (RM Suffix) Figure 2. 8-Lead SOIC_N (R Suffix) OUT A 1 8 V+ 02627-003 APPLICATIONS Wireless base station control circuits Optical network control circuits Instrumentation Sensors and controls Thermocouples Resistor thermal detectors (RTDs) Strain bridges Shunt current measurements Precision filters 4 5 V– 4 5 +IN B Figure 3. 8-Lead MSOP (RM Suffix) OUT A 1 –IN A 2 +IN A 3 V+ 4 +IN B 5 –IN B 6 OUT B 7 14 OUT D 13 –IN D Figure 4. 8-Lead SOIC_N (R Suffix) OP4177 12 +IN D 11 V– 10 +IN C 9 8 02627-005 –IN C OUT C 7 8 Figure 5. 14-Lead SOIC_N (R Suffix) Figure 6. 14-Lead TSSOP (RU Suffix) GENERAL DESCRIPTION The OPx177 family consists of very high precision, single, dual, and quad amplifiers featuring extremely low offset voltage and drift, low input bias current, low noise, and low power consumption. Outputs are stable with capacitive loads of over 1000 pF with no external compensation. Supply current is less than 500 μA per amplifier at 30 V. Internal 500 Ω series resistors protect the inputs, allowing input signal levels several volts beyond either supply without phase reversal. Unlike previous high voltage amplifiers with very low offset voltages, the OP1177 (single) and OP2177 (dual) amplifiers are available in tiny 8-lead surface-mount MSOP and 8-lead narrow SOIC packages. The OP4177 (quad) is available in TSSOP and 14-lead narrow SOIC packages. Moreover, specified performance in the MSOP and the TSSOP is identical to performance in the SOIC package. MSOP and TSSOP are available in tape and reel only. The OPx177 family offers the widest specified temperature range of any high precision amplifier in surface-mount packaging. All versions are fully specified for operation from −40°C to +125°C for the most demanding operating environments. Applications for these amplifiers include precision diode power measurement, voltage and current level setting, and level detection in optical and wireless transmission systems. Additional applications include line-powered and portable instrumentation and controls—thermocouple, RTD, strainbridge, and other sensor signal conditioning—and precision filters. Rev. E 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, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2001–2007 Analog Devices, Inc. All rights reserved. 02627-006 OUT A –IN A +IN A V+ +IN B –IN B OUT B 1 14 OP4177 OUT D –IN D +IN D V– +IN C –IN C OUT C 02627-004 OUT A –IN A +IN A V– 1 8 OP2177 V+ OUT B –IN B +IN B –IN A 2 +IN A 3 OP2177 7 OUT B 6 –IN B 02627-002 NC –IN +IN V– 1 8 OP1177 NC V+ OUT NC OP1177 7 V+ 6 OUT 5 NC V– 4 OP1177/OP2177/OP4177 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 Pin Configurations ........................................................................... 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Electrical Characteristics ............................................................. 4 Absolute Maximum Ratings............................................................ 5 Thermal Resistance ...................................................................... 5 ESD Caution .................................................................................. 5 Typical Performance Characteristics ............................................. 6 Functional Description .................................................................. 14 Total Noise-Including Source Resistors................................... 14 Gain Linearity ............................................................................. 14 Input Overvoltage Protection ................................................... 15 Output Phase Reversal ............................................................... 15 Settling Time ............................................................................... 15 Overload Recovery Time .......................................................... 15 THD + Noise ............................................................................... 16 Capacitive Load Drive ............................................................... 16 Stray Input Capacitance Compensation .................................. 17 Reducing Electromagnetic Interference .................................. 17 Proper Board Layout .................................................................. 18 Difference Amplifiers ................................................................ 18 A High Accuracy Thermocouple Amplifier ........................... 19 Low Power Linearized RTD ...................................................... 19 Single Operational Amplifier Bridge ....................................... 20 Realization of Active Filters .......................................................... 21 Band-Pass KRC or Sallen-Key Filter........................................ 21 Channel Separation .................................................................... 21 References on Noise Dynamics and Flicker Noise ............... 21 Outline Dimensions ....................................................................... 22 Ordering Guide .......................................................................... 24 REVISION HISTORY 11/07—Rev. D to Rev. E Changes to General Description .................................................... 1 Changes to Table 4 ............................................................................ 5 Updated Outline Dimensions ....................................................... 22 7/06—Rev. C to Rev. D Changes to Table 4 ............................................................................ 5 Changes to Figure 51 ...................................................................... 14 Changes to Figure 52 ...................................................................... 15 Changes to Figure 54 ...................................................................... 16 Changes to Figure 58 to Figure 61 ................................................ 17 Changes to Figure 62 and Figure 63 ............................................. 18 Changes to Figure 64 ...................................................................... 19 Changes to Figure 65 and Figure 66 ............................................. 20 Changes to Figure 67 and Figure 68 ............................................. 21 Removed SPICE Model Section ................................................... 21 Updated Outline Dimensions ....................................................... 22 Changes to Ordering Guide .......................................................... 24 4/04—Rev. B to Rev. C Changes to Ordering Guide .............................................................4 Changes to TPC 6 ..............................................................................5 Changes to TPC 26 ............................................................................7 Updated Outline Dimensions ....................................................... 17 4/02—Rev. A to Rev. B Added OP4177 ......................................................................... Global Edits to Specifications .......................................................................2 Edits to Electrical Characteristics Headings ..................................4 Edits to Ordering Guide ...................................................................4 11/01—Rev. 0 to Rev. A Edit to Features ..................................................................................1 Edits to TPC 6 ...................................................................................5 7/01—Revision 0: Initial Version Rev. E | Page 2 of 24 OP1177/OP2177/OP4177 SPECIFICATIONS ELECTRICAL CHARACTERISTICS VS = ±5.0 V, VCM = 0 V, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage OP1177 OP2177/OP4177 OP1177/OP2177 OP4177 Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP1177/OP2177 OP4177 OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current POWER SUPPLY Power Supply Rejection Ratio OP1177 OP2177/OP4177 Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density MULTIPLE AMPLIFIERS CHANNEL SEPARATION Symbol Conditions Min Typ 1 Max Unit VOS VOS VOS VOS IB IOS CMRR AVO ΔVOS/ΔT ΔVOS/ΔT VOH VOL IOUT −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VCM = −3.5 V to +3.5 V −40°C < TA < +125°C RL = 2 kΩ, VO = −3.5 V to +3.5 V −40°C < TA < +125°C −40°C < TA < +125°C IL = 1 mA, −40°C < TA < +125°C IL = 1 mA, −40°C < TA < +125°C VDROPOUT < 1.2 V −2 −1 −3.5 120 118 1000 15 15 25 25 +0.5 +0.2 126 125 2000 0.2 0.3 60 75 100 120 +2 +1 +3.5 μV μV μV μV nA nA V dB dB V/mV μV/°C μV/°C V V mA 0.7 0.9 +4 +4.1 −4.1 ±10 −4 PSRR PSRR ISY VS = ±2.5 V to ±15 V −40°C < TA < +125°C VS = ±2.5 V to ±15 V −40°C < TA < +125°C VO = 0 V −40°C < TA < +125°C RL = 2 kΩ 120 115 118 114 130 125 121 120 400 500 0.7 1.3 0.4 7.9 0.2 0.01 −120 500 600 dB dB dB dB μA μA V/μs MHz μV p-p nV/√Hz pA/√Hz μV/V dB SR GBP en p-p en in CS 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz DC f = 100 kHz 8.5 1 Typical values cover all parts within one standard deviation of the average value. Average values given in many competitor data sheets as typical give unrealistically low estimates for parameters that can have both positive and negative values. Rev. E | Page 3 of 24 OP1177/OP2177/OP4177 ELECTRICAL CHARACTERISTICS VS = ±15 V, VCM = 0 V, TA = 25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage OP1177 OP2177/OP4177 OP1177/OP2177 OP4177 Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OP1177/OP2177 OP4177 OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Short-Circuit Current POWER SUPPLY Power Supply Rejection Ratio OP1177 OP2177/OP4177 Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density MULTIPLE AMPLIFIERS CHANNEL SEPARATION Symbol Conditions Min Typ 1 Max Unit VOS VOS VOS VOS IB IOS CMRR AVO ΔVOS/ΔT ΔVOS/ΔT VOH VOL IOUT ISC −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C −40°C < TA < +125°C VCM = −13.5 V to +13.5 V, −40°C < TA < +125°C RL = 2 kΩ, VO = –13.5 V to +13.5 V −40°C < TA < +125°C −40°C < TA < +125°C IL = 1 mA, −40°C < TA < +125°C IL = 1 mA, −40°C < TA < +125°C VDROPOUT < 1.2 V −2 −1 −13.5 120 1000 15 15 25 25 +0.5 +0.2 60 75 100 120 +2 +1 +13.5 μV μV μV μV nA nA V dB V/mV 125 3000 0.2 0.3 0.7 0.9 μV/°C μV/°C V V mA mA +14 +14.1 −14.1 ±10 ±25 −14 PSRR PSRR ISY VS = ±2.5 V to ±15 V −40°C < TA < +125°C VS = ±2.5 V to ±15 V −40°C < TA < +125°C VO = 0 V −40°C < TA < +125°C RL = 2 kΩ 120 115 118 114 130 125 121 120 400 500 0.7 1.3 0.4 7.9 0.2 0.01 −120 500 600 dB dB dB dB μA μA V/μs MHz μV p-p nV/√Hz pA/√Hz μV/V dB SR GBP en p-p en in CS 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz DC f = 100 kHz 8.5 1 Typical values cover all parts within one standard deviation of the average value. Average values given in many competitor data sheets as typical give unrealistically low estimates for parameters that can have both positive and negative values. Rev. E | Page 4 of 24 OP1177/OP2177/OP4177 ABSOLUTE MAXIMUM RATINGS Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Storage Temperature Range R, RM, and RU Packages Operating Temperature Range OP1177/OP2177/OP4177 Junction Temperature Range R, RM, and RU Packages Lead Temperature, Soldering (10 sec) Rating 36 V VS− to VS+ ±Supply Voltage −65°C to +150°C −40°C to +125°C −65°C to +150°C 300°C THERMAL RESISTANCE θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 4. Thermal Resistance Package Type 8-Lead MSOP (RM-8) 1 8-Lead SOIC_N (R-8) 14-Lead SOIC_N (R-14) 14-Lead TSSOP (RU-14) 1 θJA 190 158 120 240 θJC 44 43 36 43 Unit °C/W °C/W °C/W °C/W MSOP is available in tape and reel only. 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. ESD CAUTION Rev. E | Page 5 of 24 OP1177/OP2177/OP4177 TYPICAL PERFORMANCE CHARACTERISTICS 50 45 40 1.8 VSY = ±15V 1.6 1.4 ΔOUTPUT VOLTAGE (V) VSY = ±15V TA = 25°C NUMBER OF AMPLIFIERS 35 30 25 20 15 10 5 02627-007 1.2 1.0 0.8 0.6 0.4 0.2 SOURCE SINK –40 –30 –20 –10 0 10 20 INPUT OFFSET VOLTAGE (µV) 30 40 0.01 0.1 LOAD CURRENT (mA) 1 10 Figure 7. Input Offset Voltage Distribution Figure 10. Output Voltage to Supply Rail vs. Load Current 90 3 VSY = ±15V 80 2 VSY = ±15V INPUT BIAS CURRENT (nA) NUMBER OF AMPLIFIERS 70 60 50 40 30 20 10 02627-008 1 0 –1 –2 0.05 0.15 0.25 0.35 0.45 0.55 INPUT OFFSET VOLTAGE DRIFT (µV/°C) 0.65 0 50 TEMPERATURE (°C) 100 150 Figure 8. Input Offset Voltage Drift Distribution Figure 11. Input Bias Current vs. Temperature 140 VSY = ±15V 120 60 50 40 30 GAIN 20 10 0 –10 02627-009 270 VSY = ±15V CL = 0 RL = ∞ 225 180 135 90 PHASE 45 0 –45 02627-012 NUMBER OF AMPLIFIERS 80 60 40 20 0 OPEN-LOOP GAIN (dB) 100 0 0.1 0.2 0.3 0.4 0.5 INPUT BIAS CURRENT (nA) 0.6 0.7 –20 100k 1M FREQUENCY (Hz) –90 10M Figure 9. Input Bias Current Distribution Figure 12. Open-Loop Gain and Phase Shift vs. Frequency Rev. E | Page 6 of 24 PHASE SHIFT (Degrees) 02627-011 0 –3 –50 02627-010 0 0 0.001 OP1177/OP2177/OP4177 120 100 80 CLOSED-LOOP GAIN (dB) VSY = ±15V VIN = 4mV p-p CL = 0 RL = ∞ AV = 100 AV = 10 VOLTAGE (100mV/DIV) 60 40 20 0 –20 –40 –60 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M 02627-013 VSY = ±15V CL = 1,000pF RL = 2kΩ VIN = 100mV AV = 1 AV = 1 GND –80 TIME (100µs/DIV) Figure 13. Closed-Loop Gain vs. Frequency Figure 16. Small Signal Transient Response 500 450 400 OUTPUT IMPEDANCE (Ω) 50 VSY = ±15V VIN = 50mV p-p 45 SMALL SIGNAL OVERSHOOT (%) 40 35 30 25 20 15 10 5 VSY = ±15V RL = 2kΩ VIN = 100mV p-p 350 300 250 200 150 100 50 02627-014 AV = 10 AV = 100 AV = 1 +OS –OS 1k 10k 100k FREQUENCY (Hz) 1M 1 10 100 CAPACITANCE (pF) 1k 10k Figure 14. Output Impedance vs. Frequency Figure 17. Small Signal Overshoot vs. Load Capacitance VSY = ±15V CL = 300pF RL = 2kΩ VIN = 4V AV = 1 0V –15V VSY = ±15V RL = 10kΩ AV = –100 VIN = 200mV OUTPUT VOLTAGE (1V/DIV) +200mV GND INPUT 0V 02627-018 02627-015 TIME (100µs/DIV) TIME (10µs/DIV) Figure 15. Large Signal Transient Response Figure 18. Positive Overvoltage Recovery Rev. E | Page 7 of 24 02627-017 0 100 0 02627-016 OP1177/OP2177/OP4177 15V 0V VNOISE (0.2µV/DIV) OUTPUT VSY = ±15V VSY = ±15V RL = 10kΩ AV = –100 VIN = 200mV 0V –200mV INPUT 02627-019 02627-022 TIME (4µs/DIV) TIME (1s/DIV) Figure 19. Negative Overvoltage Recovery Figure 22. 0.1 Hz to 10 Hz Input Voltage Noise 140 18 VSY = ±15V VSY = ±15V VOLTAGE NOISE DENSITY (nV/√Hz) 02627-020 120 100 16 14 12 10 8 6 4 02627-023 02627-024 CMRR (dB) 80 60 40 20 0 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 2 0 50 100 150 FREQUENCY (Hz) 200 250 Figure 20. CMRR vs. Frequency Figure 23. Voltage Noise Density vs. Frequency 140 35 VSY = ±15V VSY = ±15V 30 SHORT-CIRCUIT CURRENT (mA) 120 100 25 20 15 10 5 0 –50 +ISC –ISC PSRR (dB) –PSRR 80 +PSRR 60 40 20 0 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 02627-021 0 50 TEMPERATURE (°C) 100 150 Figure 21. PSRR vs. Frequency Figure 24. Short-Circuit Current vs. Temperature Rev. E | Page 8 of 24 OP1177/OP2177/OP4177 14.40 133 VSY = ±15V 14.35 132 131 VSY = ±15V OUTPUT VOLTAGE SWING (V) 14.30 +VOH –VOL 130 14.20 14.15 14.10 CMRR (dB) 02627-025 14.25 129 128 127 126 125 14.05 14.00 –50 124 0 50 TEMPERATURE (°C) 100 150 0 50 TEMPERATURE (°C) 100 150 Figure 25. Output Voltage Swing vs. Temperature Figure 28. CMRR vs. Temperature 0.5 0.4 133 VSY = ±15V 132 131 130 VSY = ±15V ΔOFFSET VOLTAGE (µV) 0.3 0.2 0 –0.1 –0.2 –0.3 –0.4 02627-026 PSRR (dB) 0.1 129 128 127 126 125 124 0 20 40 60 80 100 120 TIME FROM POWER SUPPLY TURN-ON (Sec) 140 0 50 TEMPERATURE (°C) 100 150 Figure 26. Warm-Up Drift Figure 29. PSRR vs. Temperature 18 VSY = ±15V 16 50 45 40 VSY = ±5V INPUT OFFSET VOLTAGE (µV) NUMBER OF AMPLIFIERS 14 12 10 8 6 4 2 02627-027 35 30 25 20 15 10 5 0 50 TEMPERATURE (°C) 100 150 –40 –30 –20 –10 0 10 20 INPUT OFFSET VOLTAGE (µV) 30 40 Figure 27. Input Offset Voltage vs. Temperature Figure 30. Input Offset Voltage Distribution Rev. E | Page 9 of 24 02627-030 0 –50 0 02627-029 –0.5 123 –50 02627-028 123 –50 OP1177/OP2177/OP4177 1.4 1.2 500 VSY = ±5V TA = 25°C OUTPUT IMPEDANCE (Ω) 450 400 VSY = ±5V VIN = 50mV p-p ΔOUTPUT VOLTAGE (V) 1.0 0.8 0.6 0.4 0.2 0 0.001 350 300 250 200 150 100 50 SINK SOURCE AV = 100 AV = 10 AV = 1 02627-031 0.01 0.1 1 LOAD CURRENT (mA) 10 1k 10k 100k FREQUENCY (Hz) 1M Figure 31. Output Voltage to Supply Rail vs. Load Current Figure 34. Output Impedance vs. Frequency 60 50 40 30 GAIN 20 10 0 –10 –20 100k PHASE VSY = ±5V CL = 0 RL = ∞ 270 225 180 135 90 45 0 –45 02627-032 PHASE SHIFT (Degrees) OPEN-LOOP GAIN (dB) VSY = ±5V CL = 300pF RL = 2kΩ VIN = 1V AV = 1 VOLTAGE (1V/DIV) GND 1M FREQUENCY (Hz) –90 10M TIME (100µs/DIV) Figure 32. Open-Loop Gain and Phase Shift vs. Frequency Figure 35. Large Signal Transient Response 120 100 80 VSY = ±5V VIN = 4mV p-p CL = 0 RL = ∞ CLOSED-LOOP GAIN (dB) 60 40 20 0 –20 –40 –60 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M 02627-033 AV = 100 AV = 10 AV = 1 VOLTAGE (50mV/DIV) VSY = ±5V CL = 1,000pF RL = 2kΩ VIN = 100mV AV = 1 GND –80 TIME (10µs/DIV) Figure 33. Closed-Loop Gain vs. Frequency Figure 36. Small Signal Transient Response Rev. E | Page 10 of 24 02627-036 02627-035 02627-034 0 100 OP1177/OP2177/OP4177 50 45 VSY = ±5V RL = 2kΩ VIN = 100mV INPUT SMALL SIGNAL OVERSHOOT (%) VS = ±5V AV = 1 RL = 10kΩ 40 35 30 25 20 15 10 5 1 VOLTAGE (2V/DIV) GND +OS –OS OUTPUT 10 100 CAPACITANCE (pF) 1k 10k 02627-037 TIME (200µs/DIV) Figure 37. Small Signal Overshoot vs. Load Capacitance Figure 40. No Phase Reversal 0V –15V VSY = ±5V RL = 10kΩ AV = –100 VIN = 200mV 140 VSY = ±5V OUTPUT 120 100 CMRR (dB) 80 60 40 +200mV INPUT 0V 02627-038 20 0 TIME (4µs/DIV) 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M Figure 38. Positive Overvoltage Recovery Figure 41. CMRR vs. Frequency 5V 0V OUTPUT VSY = ±5V RL = 10kΩ AV = –100 VIN = 200mV 200 180 160 140 PSRR (dB) VSY = ±5V 120 100 INPUT –PSRR 80 60 40 0V +PSRR –200mV 02627-039 20 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 02627-042 0 TIME (4µs/DIV) Figure 39. Negative Overvoltage Recovery Figure 42. PSRR vs. Frequency Rev. E | Page 11 of 24 02627-041 02627-040 0 OP1177/OP2177/OP4177 VSY = ±5V 4.40 VSY = ±5V 4.35 OUTPUT VOLTAGE SWING (V) 4.30 VNOISE (0.2µV/DIV) +VOH 4.25 4.20 4.15 4.10 4.05 –VOL 02627-043 TIME (1s/DIV) 0 50 TEMPERATURE (°C) 100 150 Figure 43. 0.1 Hz to 10 Hz Input Voltage Noise Figure 46. Output Voltage Swing vs. Temperature 18 25 VSY = ±5V VOLTAGE NOISE DENSITY (nV/√Hz) VSY = ±5V 20 16 14 12 10 8 6 4 02627-044 02627-047 02627-048 INPUT OFFSET VOLTAGE (µV) 15 10 5 2 0 50 100 150 FREQUENCY (Hz) 200 250 0 –50 0 50 TEMPERATURE (°C) 100 150 Figure 44. Voltage Noise Density vs. Frequency Figure 47. Input Offset Voltage vs. Temperature 35 600 VSY = ±5V 30 SHORT-CIRCUIT CURRENT (mA) 500 +ISC VSY = ±15V SUPPLY CURRENT (µA) 25 –ISC 20 15 10 5 0 –50 400 VSY = ±5V 300 200 100 0 50 TEMPERATURE (°C) 100 150 02627-045 0 –50 0 50 TEMPERATURE (°C) 100 150 Figure 45. Short-Circuit Current vs. Temperature Figure 48. Supply Current vs. Temperature Rev. E | Page 12 of 24 02627-046 4.00 –50 OP1177/OP2177/OP4177 450 0 TA = 25°C 400 –20 CHANNEL SEPARATION (dB) SUPPLY CURRENT (µA) 350 300 250 200 150 100 50 02627-049 –40 –60 –80 –100 –120 –140 02627-050 0 –160 10 100 1k 10k FREQUENCY (Hz) 100k 1M 0 5 10 15 20 25 30 35 SUPPLY VOLTAGE (V) Figure 49. Supply Current vs. Supply Voltage Figure 50. Channel Separation vs. Frequency Rev. E | Page 13 of 24 OP1177/OP2177/OP4177 FUNCTIONAL DESCRIPTION The OPx177 series is the fourth generation of Analog Devices, Inc., industry-standard OP07 amplifier family. OPx177 is a high precision, low noise operational amplifier with a combination of extremely low offset voltage and very low input bias currents. Unlike JFET amplifiers, the low bias and offset currents are relatively insensitive to ambient temperatures, even up to 125°C. Analog Devices proprietary process technology and linear design expertise has produced a high voltage amplifier with superior performance to the OP07, OP77, and OP177 in a tiny MSOP 8­lead package. Despite its small size, the OPx177 offers numerous improvements, including low wideband noise, very wide input and output voltage range, lower input bias current, and complete freedom from phase inversion. OPx177 has a specified operating temperature range as wide as any similar device in a plastic surface-mount package. This is increasingly important as PCB and overall system sizes continue to shrink, causing internal system temperatures to rise. Power consumption is reduced by a factor of four from the OP177, and bandwidth and slew rate increase by a factor of two. The low power dissipation and very stable performance vs. temperature also act to reduce warmup drift errors to insignificant levels. Open-loop gain linearity under heavy loads is superior to competitive parts, such as the OPA277, improving dc accuracy and reducing distortion in circuits with high closed-loop gains. Inputs are internally protected from overvoltage conditions referenced to either supply rail. Like any high performance amplifier, maximum performance is achieved by following appropriate circuit and PCB guidelines. The following sections provide practical advice on getting the most out of the OPx177 under a variety of application conditions. For RS < 3.9 kΩ, en dominates and en,TOTAL ≈ en For 3.9 kΩ < RS < 412 kΩ, voltage noise of the amplifier, the current noise of the amplifier translated through the source resistor, and the thermal noise from the source resistor all contribute to the total noise. For RS > 412 kΩ, the current noise dominates and en,TOTAL ≈ inRS The total equivalent rms noise over a specific bandwidth is expressed as en = (e n , TOTAL ) BW where BW is the bandwidth in hertz. The preceding analysis is valid for frequencies larger than 50 Hz. When considering lower frequencies, flicker noise (also known as 1/f noise) must be taken into account. For a reference on noise calculations, refer to the Band-Pass KRC or Sallen-Key Filter section. GAIN LINEARITY Gain linearity reduces errors in closed-loop configurations. The straighter the gain curve, the lower the maximum error over the input signal range. This is especially true for circuits with high closed-loop gains. The OP1177 has excellent gain linearity even with heavy loads, as shown in Figure 51. Compare its performance to the OPA277, shown in Figure 52. Both devices are measured under identical conditions, with RL = 2 kΩ. The OP2177 (dual) has virtually no distortion at lower voltages. Compared to the OPA277 at several supply voltages and various loads, OP1177 performance far exceeds that of its counterpart. VSY = ±15V RL = 2kΩ TOTAL NOISE-INCLUDING SOURCE RESISTORS The low input current noise and input bias current of the OPx177 make it useful for circuits with substantial input source resistance. Input offset voltage increases by less than 1 μV maximum per 500 Ω of source resistance. The total noise density of the OPx177 is (10µV/DIV) en, TOTAL = en2 + (in RS ) 2 + 4kTRS where: en is the input voltage noise density. in is the input current noise density. RS is the source resistance at the noninverting terminal. k is Boltzmann’s constant (1.38 × 10−23 J/K). T is the ambient temperature in Kelvin (T = 273 + temperature in degrees Celsius). OP1177 (5V/DIV) Figure 51. Gain Linearity Rev. E | Page 14 of 24 02627-051 OP1177/OP2177/OP4177 VSY = ±15V RL = 2kΩ VSY = 10V AV = 1 VOLTAGE (5V/DIV) VIN VOUT (10µV/DIV) OPA277 02627-052 (5V/DIV) TIME (400µs/DIV) Figure 52. Gain Linearity Figure 53. No Phase Reversal INPUT OVERVOLTAGE PROTECTION When input voltages exceed the positive or negative supply voltage, most amplifiers require external resistors to protect them from damage. The OPx177 has internal protective circuitry that allows voltages as high as 2.5 V beyond the supplies to be applied at the input of either terminal without any harmful effects. Use an additional resistor in series with the inputs if the voltage exceeds the supplies by more than 2.5 V. The value of the resistor can be determined from the formula SETTLING TIME Settling time is defined as the time it takes an amplifier output to reach and remain within a percentage of its final value after application of an input pulse. It is especially important in measurement and control circuits in which amplifiers buffer ADC inputs or DAC outputs. To minimize settling time in amplifier circuits, use proper bypassing of power supplies and an appropriate choice of circuit components. Resistors should be metal film types, because they have less stray capacitance and inductance than their wire-wound counterparts. Capacitors should be polystyrene or polycarbonate types to minimize dielectric absorption. The leads from the power supply should be kept as short as possible to minimize capacitance and inductance. The OPx177 has a settling time of about 45 μs to 0.01% (1 mV) with a 10 V step applied to the input in a noninverting unity gain. (V IN − VS ) ≤ 5 mA R S + 500 Ω With the OPx177 low input offset current of