® OPA OPA227 422 7 OPA 227 OPA OPA2227 OPA4227 222 7 OPA 42 27 OPA2 OPA2 227 27 OPA228 OPA2228 OPA4228 For most current data sheet and other product information, visit www.burr-brown.com High Precision, Low Noise OPERATIONAL AMPLIFIERS FEATURES DESCRIPTION ● LOW NOISE: 3nV/√Hz ● WIDE BANDWIDTH: OPA227: 8MHz, 2.3V/µs OPA228: 33MHz, 10V/µs The OPA227 and OPA228 series op amps combine low noise and wide bandwidth with high precision to make them the ideal choice for applications requiring both ac and precision dc performance. The OPA227 is unity gain stable and features high slew rate (2.3V/µs) and wide bandwidth (8MHz). The OPA228 is optimized for closed-loop gains of 5 or greater, and offers higher speed with a slew rate of 10V/µs and a bandwidth of 33MHz. The OPA227 and OPA228 series op amps are ideal for professional audio equipment. In addition, low quiescent current and low cost make them ideal for portable applications requiring high precision. The OPA227 and OPA228 series op amps are pinfor-pin replacements for the industry standard OP-27 and OP-37 with substantial improvements across the board. The dual and quad versions are available for space savings and per-channel cost reduction. The OPA227, OPA228, OPA2227, and OPA2228 are available in DIP-8 and SO-8 packages. The OPA4227 and OPA4228 are available in DIP-14 and SO-14 packages with standard pin configurations. Operation is specified from –40°C to +85°C. ● SETTLING TIME: 5µs (significant improvement over OP-27) ● ● ● ● ● ● HIGH CMRR: 138dB HIGH OPEN-LOOP GAIN: 160dB LOW INPUT BIAS CURRENT: 10nA max LOW OFFSET VOLTAGE: 75µV max WIDE SUPPLY RANGE: ±2.5V to ±18V OPA227 REPLACES OP-27, LT1007, MAX427 ● OPA228 REPLACES OP-37, LT1037, MAX437 ● SINGLE, DUAL, AND QUAD VERSIONS APPLICATIONS ● ● ● ● ● ● ● DATA ACQUISITION TELECOM EQUIPMENT GEOPHYSICAL ANALYSIS VIBRATION ANALYSIS SPECTRAL ANALYSIS PROFESSIONAL AUDIO EQUIPMENT ACTIVE FILTERS OPA4227, OPA4228 ● POWER SUPPLY CONTROL SPICE Model available for OPA227 at www.burr-brown.com OPA227, OPA228 1 –In A 2 A Trim 1 8 Trim –In 2 7 V+ +In 3 6 Output V– 4 5 NC DIP-8, SO-8 Out A OPA2227, OPA2228 Out A 1 –In A 2 +In A 3 V– 4 A B 8 V+ 7 Out B 6 –In B 5 +In B 14 Out D 13 –In D D +In A 3 12 +In D V+ 4 11 V– +In B 5 10 +In C B C –In B 6 9 –In C Out B 7 8 Out C DIP-14, SO-14 DIP-8, SO-8 International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 © 1998 Burr-Brown Corporation PDS-1494B Printed in U.S.A. May, 1999 SPECIFICATIONS: VS = ±5V to ±15V OPA227 Series At TA = +25°C, and RL = 10kΩ, unless otherwise noted. Boldface limits apply over the specified temperature range, TA = –40°C to +85°C. OPA227PA, UA OPA2227PA, UA OPA4227PA, UA OPA227P, U OPA2227P, U PARAMETER CONDITION OFFSET VOLTAGE Input Offset Voltage VOS OTA = –40°C to +85°Cver Temperature vs Temperature dVOS/dT vs Power Supply PSRR TA = –40°C to +85°C vs Time Channel Separation (dual, quad) INPUT BIAS CURRENT Input Bias Current TA = –40°C to +85°C Input Offset Current TA = –40°C to +85°C MIN TYP ±5 ±0.1 VS = ±2.5V to ±18V ±0.5 ±2.5 IOS ±2.5 Input Voltage Noise Density, f = 10Hz en f = 100Hz f = 1kHz Current Noise Density, f = 1kHz in 90 15 3.5 3 3 0.4 NOISE Input Voltage Noise, f = 0.1Hz to 10Hz VCM CMRR AOL VO = (V–)+2V to (V+)–2V, RL = 10kΩ VO = (V–)+3.5V to (V+)–3.5V, RL = 600Ω TA = –40°C to +85°C FREQUENCY RESPONSE Gain Bandwidth Product GBW Slew Rate SR Settling Time: 0.1% 0.01% Overload Recovery Time Total Harmonic Distortion + Noise THD+N RL = RL = RL = RL = 10kΩ 10kΩ 600Ω 600Ω TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance SO-8 Surface Mount DIP-8 DIP-14 SO-14 Surface Mount IQ IO = 0 IO = 0 ±10 ✻ ±10 ✻ ±10 ±10 ✻ ✻ ✻ ✻ ✻ ✻ ✻ 160 2 ±200 ✻ ✻ µV µV µV/°C µV/V µV/V µV/mo µV/V dB ✻ ✻ ✻ ✻ nA nA nA nA ±200 ±2 nVp-p nVrms nV/√Hz nV/√Hz nV/√Hz pA/√Hz ✻ ✻ V dB dB ✻ ✻ Ω || pF Ω || pF ✻ dB dB dB dB ✻ ✻ ✻ ✻ ✻ ✻ ✻ (V+)–2 (V+)–2 (V+)–3.5 (V+)–3.5 150 100 80 100 UNITS ✻ ✻ ✻ ✻ ✻ ✻ 160 ±3.7 MAX ✻ ✻ ✻ (V+)–2 –40 –55 –65 θJA OPA227, 2227, 4227 OPA228, 2228, 4228 ✻ 8 2.3 5 5.6 1.3 0.00005 ±5 ±2.5 ✻ Specifications same as OPA227P, U. ® ±0.3 ✻ ✻ ✻ ✻ ±45 See Typical Curve VS TYP ±10 ±2 ±2 138 (V–)+2 (V–)+2 (V–)+3.5 (V–)+3.5 ISC CLOAD POWER SUPPLY Specified Voltage Range Operating Voltage Range Quiescent Current (per amplifier) TA = –40°C to +85°C 132 132 132 132 G = 1, 10V Step, CL = 100pF G = 1, 10V Step, CL = 100pF VIN • G = VS f = 1kHz, G = 1, VO = 3.5Vrms OUTPUT Voltage Output TA = –40°C to +85°C ±75 ±100 ±0.6 107 || 12 109 || 3 VCM = (V–)+2V to (V+)–2V OPEN-LOOP GAIN Open-Loop Voltage Gain TA = –40°C to +85°C TA = –40°C to +85°C Short-Circuit Current Capacitive Load Drive (V–)+2 120 120 VCM = (V–)+2V to (V+)–2V INPUT IMPEDANCE Differential Common-Mode MIN 0.2 0.2 110 dc f = 1kHz, RL = 5kΩ IB INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection TA = –40°C to +85°C MAX MHz V/µs µs µs µs % ✻ ✻ ✻ ✻ V V V V mA ✻ ✻ ✻ ✻ V V mA mA ✻ ✻ ✻ °C °C °C ✻ ✻ ±15 ±18 ±3.8 ±4.2 ✻ ✻ +85 +125 +150 ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ °C/W °C/W °C/W °C/W SPECIFICATIONS: VS = ±5V to ±15V OPA228 Series At TA = +25°C, and RL = 10kΩ, unless otherwise noted. Boldface limits apply over the specified temperature range, TA = –40°C to +85°C. OPA228PA, UA OPA2228PA, UA OPA4228PA, UA OPA228P, U OPA2228P, U PARAMETER CONDITION OFFSET VOLTAGE Input Offset Voltage VOS OTA = –40°C to +85°Cver Temperature vs Temperature dVOS/dT vs Power Supply PSRR TA = –40°C to +85°C vs Time Channel Separation (dual, quad) INPUT BIAS CURRENT Input Bias Current TA = –40°C to +85°C Input Offset Current TA = –40°C to +85°C MIN TYP ±5 ±0.1 VS = ±2.5V to ±18V ±0.5 ±2.5 IOS ±2.5 Input Voltage Noise Density, f = 10Hz en f = 100Hz f = 1kHz Current Noise Density, f = 1kHz in 90 15 3.5 3 3 0.4 NOISE Input Voltage Noise, f = 0.1Hz to 10Hz VCM CMRR INPUT IMPEDANCE Differential Common-Mode AOL VO = (V–)+2V to (V+)–2V, RL = 10kΩ VO = (V–)+3.5V to (V+)–3.5V, RL = 600Ω TA = –40°C to +85°C FREQUENCY RESPONSE Minimum Closed-Loop Gain Gain Bandwidth Product GBW Slew Rate SR Settling Time: 0.1% 0.01% Overload Recovery Time Total Harmonic Distortion + Noise THD+N OUTPUT Voltage Output TA = –40°C to +85°C TA = –40°C to +85°C Short-Circuit Current Capacitive Load Drive VCM = (V–)+2V to (V+)–2V (V–)+2 120 120 10kΩ 10kΩ 600Ω 600Ω TEMPERATURE RANGE Specified Range Operating Range Storage Range Thermal Resistance SO-8 Surface Mount DIP-8 DIP-14 SO-14 Surface Mount IQ ±0.3 ✻ ±10 ✻ ±10 ✻ ±10 ±10 IO = 0 IO = 0 (V+)–2 ✻ ✻ ✻ ✻ ✻ ✻ ✻ 160 160 –40 –55 –65 θJA 150 100 80 100 ±200 ✻ ✻ µV µV µV/°C µV/V µV/V µV/mo µV/V dB ✻ ✻ ✻ ✻ nA nA nA nA ±200 ±2 nVp-p nVrms nV/√Hz nV/√Hz nV/√Hz pA/√Hz ✻ ✻ V dB dB ✻ ✻ Ω || pF Ω || pF ✻ dB dB dB dB ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ (V+)–2 (V+)–2 (V+)–3.5 (V+)–3.5 ±3.7 UNITS ✻ ✻ ✻ ✻ ✻ ✻ 5 33 11 1.5 2 0.6 0.00005 ±5 ±2.5 MAX ✻ ✻ ✻ ✻ ✻ ✻ ✻ ±45 See Typical Curve VS TYP ±10 ±2 ±2 138 (V–)+2 (V–)+2 (V–)+3.5 (V–)+3.5 ISC CLOAD POWER SUPPLY Specified Voltage Range Operating Voltage Range Quiescent Current (per amplifier) TA = –40°C to +85°C 132 132 132 132 G = 5, 10V Step, CL = 100pF, CF =12pF G = 5, 10V Step, CL = 100pF, CF =12pF VIN • G = VS f = 1kHz, G = 5, VO = 3.5Vrms RL = RL = RL = RL = ±75 ±100 ±0.6 107 || 12 109 || 3 VCM = (V–)+2V to (V+)–2V OPEN-LOOP GAIN Open-Loop Voltage Gain TA = –40°C to +85°C MIN 0.2 0.2 110 dc f = 1kHz, RL = 5kΩ IB INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection TA = –40°C to +85°C MAX V/V MHz V/µs µs µs µs % ✻ ✻ ✻ ✻ V V V V mA ✻ ✻ ✻ ✻ V V mA mA ✻ ✻ ✻ °C °C °C ✻ ✻ ±15 ±18 ±3.8 ±4.2 ✻ ✻ +85 +125 +150 ✻ ✻ ✻ ✻ ✻ ✻ ✻ ✻ °C/W °C/W °C/W °C/W ✻ Specifications same as OPA228P, U. 3 OPA227, 2227, 4227 OPA228, 2228, 4228 ® ABSOLUTE MAXIMUM RATINGS(1) ELECTROSTATIC DISCHARGE SENSITIVITY Supply Voltage .................................................................................. ±18V Signal Input Terminals, Voltage ........................ (V–) –0.7V to (V+) +0.7V Current ....................................................... 20mA Output Short-Circuit(2) .............................................................. Continuous Operating Temperature .................................................. –55°C to +125°C Storage Temperature ..................................................... –65°C to +150°C Junction Temperature ...................................................................... 150°C Lead Temperature (soldering, 10s) ................................................. 300°C This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. NOTE: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. (2) Short-circuit to ground, one amplifier per package. PACKAGE/ORDERING INFORMATION OFFSET VOLTAGE max, µV OFFSET VOLTAGE DRIFT max, µV/°C PACKAGE PACKAGE DRAWING NUMBER(1) TEMPERATURE RANGE ORDERING NUMBER(2) TRANSPORT MEDIA Single OPA227PA OPA227P OPA227UA " OPA227U " ±200 ±75 ±200 " ±75 " ±2 ±0.6 ±2 " ±0.6 " DIP-8 DIP-8 SO-8 Surface Mount " SO-8 Surface Mount " 006 006 182 " 182 " –40°C to +85°C –40°C to +85°C –40°C to +85°C " –40°C to +85°C " OPA227PA OPA227P OPA227UA OPA227UA/2K5 OPA227U OPA227U/2K5 Rails Rails Rails Tape and Reel Rails Tape and Reel Dual OPA2227PA OPA2227P OPA2227UA " OPA2227U " ±200 ±75 ±200 " ±75 " ±2 ±0.6 ±2 " ±0.6 " DIP-8 DIP-8 SO-8 Surface Mount " SO-8 Surface Mount " 006 006 182 " 182 " –40°C to +85°C –40°C to +85°C –40°C to +85°C " –40°C to +85°C " OPA2227PA OPA2227P OPA2227UA OPA2227UA/2K5 OPA2227U OPA2227U/2K5 Rails Rails Rails Tape and Reel Rails Tape and Reel Quad OPA4227PA OPA4227UA " ±200 ±200 " ±2 ±2 " DIP-14 SO-14 Surface Mount " 010 235 " –40°C to +85°C –40°C to +85°C " OPA4227PA OPA4227UA OPA4227UA/2K5 Rails Rails Tape and Reel Single OPA228PA OPA228P OPA228UA " OPA228U " ±200 ±75 ±200 " ±75 " ±2 ±0.6 ±2 " ±0.6 " DIP-8 DIP-8 SO-8 Surface Mount " SO-8 Surface Mount " 006 006 182 " 182 " –40°C to +85°C –40°C to +85°C –40°C to +85°C " –40°C to +85°C " OPA228PA OPA228P OPA228UA OPA228UA/2K5 OPA228U OPA228U/2K5 Rails Rails Rails Tape and Reel Rails Tape and Reel Dual OPA2228PA OPA2228P OPA2228UA " OPA2228U " ±200 ±75 ±200 " ±75 " ±2 ±0.6 ±2 " ±0.6 " DIP-8 DIP-8 SO-8 Surface Mount " SO-8 Surface Mount " 006 006 182 " 182 " –40°C to +85°C –40°C to +85°C –40°C to +85°C " –40°C to +85°C " OPA2228PA OPA2228P OPA2228UA OPA2228UA/2K5 OPA2228U OPA2228U/2K5 Rails Rails Rails Tape and Reel Rails Tape and Reel Quad OPA4228PA OPA4228UA " ±200 ±200 " ±2 ±2 " DIP-14 SO-14 Surface Mount " 010 235 " –40°C to +85°C –40°C to +85°C " OPA4228PA OPA4228UA OPA4228UA/2K5 Rails Rails Tape and Reel PRODUCT OPA227 Series OPA228 Series NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) Products followed by a slash (/) are only available in Tape and Reel in the quantities indicated (e.g. /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of “OPA227UA/2K5” will get a single 2500 piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book. The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® OPA227, 2227, 4227 OPA228, 2228, 4228 4 TYPICAL PERFORMANCE CURVES At TA = +25°C, RL = 10kΩ, and VS = ±15V, unless otherwise noted. OPEN-LOOP GAIN/PHASE vs FREQUENCY OPEN-LOOP GAIN/PHASE vs FREQUENCY G AOL (dB) 120 100 φ 80 –20 160 –40 140 –60 120 –80 100 –100 0 OPA228 –20 –40 G –60 –80 φ 80 –100 60 –120 –140 40 –140 20 –160 20 –160 0 –180 0 –180 60 –120 40 –20 0.01 0.10 1 10 100 1k –20 0.01 0.10 –200 10k 100k 1M 10M 100M 1 10 100 1k –200 10k 100k 1M 10M 100M Frequency (Hz) Frequency (Hz) POWER SUPPLY AND COMMON-MODE REJECTION RATIO vs FREQUENCY INPUT VOLTAGE AND CURRENT NOISE SPECTRAL DENSITY vs FREQUENCY 140 100k 120 Voltage Noise (nV/√Hz) Current Noise (fA/√Hz) PSRR, CMRR (dB) +CMRR 100 +PSRR 80 60 –PSRR 40 -20 –0 Current Noise 1k 100 10 Voltage Noise 1 0.1 1 10 100 1k 10k 100k 1M 0.1 1 10 100 1k 10k Frequency (Hz) Frequency (Hz) TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY TOTAL HARMONIC DISTORTION + NOISE vs FREQUENCY 0.01 0.01 OPA227 VOUT = 3.5Vrms THD+Noise (%) VOUT = 3.5Vrms THD+Noise (%) 10k 0.001 0.0001 G = 1, RL = 10kΩ 0.00001 OPA228 0.001 0.0001 G = 1, RL = 10kΩ 0.00001 20 100 1k 10k 20k 20 Frequency (Hz) 100 1k 10k 50k Frequency (Hz) 5 OPA227, 2227, 4227 OPA228, 2228, 4228 ® Phase (°) 140 180 AOL (dB) OPA227 160 0 Phase (°) 180 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C, RL =10kΩ, and VS = ±15V, unless otherwise noted. INPUT NOISE VOLTAGE vs TIME CHANNEL SEPARATION vs FREQUENCY 50nV/div Channel Separation (dB) 140 120 100 80 Dual and quad devices. G = 1, all channels. Quad measured Channel A to D, or B to C; other combinations yield similiar or improved rejection. 60 40 10 1s/div 100 1k 10k 100k 1M Frequency (Hz) OFFSET VOLTAGE PRODUCTION DISTRIBUTION VOLTAGE NOISE DISTRIBUTION (10Hz) 17.5 24 Typical distribution of packaged units. Percent of Amplifiers (%) Percent of Units (%) 15.0 16 8 12.5 10.0 5.5 5.0 2.5 0 0 3.16 3.25 3.34 3.43 3.51 3.60 –150 –135 –120 –105 –90 –75 –60 –45 –30 –15 0 15 30 45 60 75 90 105 120 135 150 0 3.69 3.78 Noise (nV/√Hz) Offset Voltage (µV) OFFSET VOLTAGE DRIFT PRODUCTION DISTRIBUTION WARM-UP OFFSET VOLTAGE DRIFT 12 10 8 Offset Voltage Change (µV) Percent of Amplifiers (%) Typical distribution of packaged units. 8 4 6 4 2 0 –2 –4 –6 –8 0 –10 0 0.5 1.0 0 1.5 OPA227, 2227, 4227 OPA228, 2228, 4228 100 150 200 250 Time from Power Supply Turn-On (s) Offset Voltage Drift (µV)/°C ® 50 6 300 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C, RL = 10kΩ, and VS = ±15V, unless otherwise noted. AOL, CMRR, PSRR vs TEMPERATURE AOL, CMRR, PSRR vs TEMPERATURE 160 160 AOL AOL, CMRR, PSRR (dB) AOL, CMRR, PSRR (dB) CMRR 140 130 PSRR 120 110 100 90 80 OPA227 70 60 –75 –50 AOL 150 150 CMRR 140 130 PSRR 120 110 100 90 80 OPA228 70 –25 0 25 50 75 100 60 –75 125 –50 –25 0 Short-Circuit Current (mA) Input Bias Current (nA) 75 100 125 60 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –40 –20 0 20 40 60 80 50 40 30 20 10 0 –75 100 120 140 –ISC +ISC –50 –25 0 25 50 75 100 125 Temperature (°C) Temperature (°C) QUIESCENT CURRENT vs SUPPLY VOLTAGE QUIESCENT CURRENT vs TEMPERATURE 3.8 5.0 ±18V ±15V ±12V ±10V 4.5 4.0 Quiescent Current (mA) Quiescent Current (mA) 50 SHORT-CIRCUIT CURRENT vs TEMPERATURE INPUT BIAS CURRENT vs TEMPERATURE 2.0 –2.0 –60 25 Temperature (°C) Temperature (°C) ±5V ±2.5V 3.5 3.0 3.6 3.4 3.2 3.0 2.8 2.5 –60 –40 –20 0 20 40 60 80 0 100 120 140 2 4 6 8 10 12 14 16 18 20 Supply Voltage (±V) Temperature (°C) 7 OPA227, 2227, 4227 OPA228, 2228, 4228 ® TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C, RL = 10kΩ, and VS = ±15V, unless otherwise noted. SLEW RATE vs TEMPERATURE SLEW RATE vs TEMPERATURE 3.0 12 OPA227 OPA228 10 Positive Slew Rate Negative Slew Rate Slew Rate (µV/V) Slew Rate (µV/V) 2.5 2.0 1.5 1.0 8 6 4 RLOAD = 2kΩ CLOAD = 100pF 0.5 0 0 –75 –50 –25 0 25 50 75 100 125 –75 –50 –25 0 50 75 Temperature (°C) CHANGE IN INPUT BIAS CURRENT vs POWER SUPPLY VOLTAGE CHANGE IN INPUT BIAS CURRENT vs COMMON-MODE VOLTAGE 100 125 1.5 Curve shows normalized change in bias current with respect to VS = ±10V. Typical IB may range from –2nA to +2nA at VS = ±10V. 1.5 1.0 Curve shows normalized change in bias current with respect to VCM = 0V. Typical IB may range from –2nA to +2nA at VCM = 0V. 1.0 0.5 ∆IB (nA) 0.5 0 –0.5 VS = ±15V 0 –0.5 VS = ±5V –1.0 –1.0 –1.5 –1.5 –2.0 0 5 10 15 20 25 30 35 –15 40 –10 Output Voltage Swing (V) VS = ±15V, 10V Step CL = 1500pF RL = 2kΩ OPA227 0.01% 10 0 5 10 15 OUTPUT VOLTAGE SWING vs OUTPUT CURRENT SETTLING TIME vs CLOSED-LOOP GAIN 100 –5 Common-Mode Voltage (V) Supply Voltage (V) Settling Time (µs) 25 Temperature (°C) 2.0 ∆IB (nA) RLOAD = 2kΩ CLOAD = 100pF 2 0.1% OPA228 0.01% 0.1% 15 V+ 14 (V+) –1V 13 (V+) –2V 12 –40°C 125°C 85°C 25°C 11 10 –10 –55°C 85°C –11 (V+) –3V –55°C 125°C –12 (V–) +3V –40°C 25°C –13 (V–) +2V –14 (V–) +1V –15 1 ±1 ±10 ±100 OPA227, 2227, 4227 OPA228, 2228, 4228 10 20 30 40 Output Current (mA) Gain (V/V) ® V– 0 8 50 60 TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C, RL = 10kΩ, and VS = ±15V, unless otherwise noted. SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 30 70 VS = ±15V OPA227 OPA227 60 Gain = +10 50 Overshoot (%) 20 15 VS = ±5V 10 40 30 20 5 0 Gain = –10 Gain = –1 Gain = +1 10 0 1k 10k 100k 1M 10M 1 10 100 1k 10k Frequency (Hz) Load Capacitance (pF) LARGE-SIGNAL STEP RESPONSE G = –1, CL = 1500pF SMALL-SIGNAL STEP RESPONSE G = +1, CL = 1000pF OPA227 100k 25mV/div OPA227 2V/div 400ns/div 5µs/div SMALL-SIGNAL STEP RESPONSE G = +1, CL = 5pF OPA227 25mV/div Output Voltage (Vp-p) 25 400ns/div 9 OPA227, 2227, 4227 OPA228, 2228, 4228 ® TYPICAL PERFORMANCE CURVES (CONT) At TA = +25°C, RL = 10kΩ, and VS = ±15V, unless otherwise noted. SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 30 70 VS = ±15V OPA228 OPA228 60 50 Overshoot (%) 20 15 VS = ±5V 10 G = –100 40 30 G = +100 20 G = ±10 5 10 0 0 10k 1k 100k 1M 1 10M 10 Frequency (Hz) 100 10k SMALL-SIGNAL STEP RESPONSE G = +10, CL = 1000pF, RL = 1.8kΩ LARGE-SIGNAL STEP RESPONSE G = –10, CL = 100pF OPA228 200mV/div OPA228 500ns/div 2µs/div SMALL-SIGNAL STEP RESPONSE G = +10, CL = 5pF, RL = 1.8kΩ 200mV/div OPA228 500ns/div ® 1k Load Capacitance (pF) 5V/div Output Voltage (Vp-p) 25 OPA227, 2227, 4227 OPA228, 2228, 4228 10 100k APPLICATIONS INFORMATION Trim range exceeds offset voltage specification V+ The OPA227 and OPA228 series are precision op amps with very low noise. The OPA227 series is unity-gain stable with a slew rate of 2.3V/µs and 8MHz bandwidth. The OPA228 series is optimized for higher-speed applications with gains of 5 or greater, featuring a slew rate of 10V/µs and 33MHz bandwidth. Applications with noisy or high impedance power supplies may require decoupling capacitors close to the device pins. In most cases, 0.1µF capacitors are adequate. 0.1µF 20kΩ 7 2 1 8 OPA227 6 3 OPA227 and OPA228 single op amps only. Use offset adjust pins only to null offset voltage of op amp. See text. 4 0.1µF V– OFFSET VOLTAGE AND DRIFT The OPA227 and OPA228 series have very low offset voltage and drift. To achieve highest dc precision, circuit layout and mechanical conditions should be optimized. Connections of dissimilar metals can generate thermal potentials at the op amp inputs which can degrade the offset voltage and drift. These thermocouple effects can exceed the inherent drift of the amplifier and ultimately degrade its performance. The thermal potentials can be made to cancel by assuring that they are equal at both input terminals. In addition: FIGURE 1. OPA227 Offset Voltage Trim Circuit. amp. This adjustment should not be used to compensate for offsets created elsewhere in the system since this can introduce additional temperature drift. INPUT PROTECTION Back-to-back diodes (see Figure 2) are used for input protection on the OPA227 and OPA228. Exceeding the turn-on threshold of these diodes, as in a pulse condition, can cause current to flow through the input protection diodes due to the amplifier’s finite slew rate. Without external current-limiting resistors, the input devices can be destroyed. Sources of high input current can cause subtle damage to the amplifier. Although the unit may still be functional, important parameters such as input offset voltage, drift, and noise may shift. • Keep thermal mass of the connections made to the two input terminals similar. • Locate heat sources as far as possible from the critical input circuitry. • Shield op amp and input circuitry from air currents such as those created by cooling fans. OPERATING VOLTAGE RF 500Ω OPA227 and OPA228 series op amps operate from ±2.5V to ±18V supplies with excellent performance. Unlike most op amps which are specified at only one supply voltage, the OPA227 series is specified for real-world applications; a single set of specifications applies over the ±5V to ±15V supply range. Specifications are guaranteed for applications between ±5V and ±15V power supplies. Some applications do not require equal positive and negative output voltage swing. Power supply voltages do not need to be equal. The OPA227 and OPA228 series can operate with as little as 5V between the supplies and with up to 36V between the supplies. For example, the positive supply could be set to 25V with the negative supply at –5V or vice-versa. In addition, key parameters are guaranteed over the specified temperature range, –40°C to +85°C. Parameters which vary significantly with operating voltage or temperature are shown in the Typical Performance Curves. – OPA227 Input Output + FIGURE 2. Pulsed Operation. When using the OPA227 as a unity-gain buffer (follower), the input current should be limited to 20mA. This can be accomplished by inserting a feedback resistor or a resistor in series with the source. Sufficient resistor size can be calculated: RX = VS/20mA – RSOURCE where RX is either in series with the source or inserted in the feedback path. For example, for a 10V pulse (VS = 10V), total loop resistance must be 500Ω. If the source impedance is large enough to sufficiently limit the current on its own, no additional resistors are needed. The size of any external resistors must be carefully chosen since they will increase noise. See the Noise Performance section of this data sheet for further information on noise calculation. Figure 2 shows an example implementing a currentlimiting feedback resistor. OFFSET VOLTAGE ADJUSTMENT The OPA227 and OPA228 series are laser-trimmed for very low offset and drift so most applications will not require external adjustment. However, the OPA227 and OPA228 (single versions) provide offset voltage trim connections on pins 1 and 8. Offset voltage can be adjusted by connecting a potentiometer as shown in Figure 1. This adjustment should be used only to null the offset of the op 11 OPA227, 2227, 4227 OPA228, 2228, 4228 ® INPUT BIAS CURRENT CANCELLATION NOISE PERFORMANCE The input bias current of the OPA227 and OPA228 series is internally compensated with an equal and opposite cancellation current. The resulting input bias current is the difference between with input bias current and the cancellation current. The residual input bias current can be positive or negative. Figure 4 shows total circuit noise for varying source impedances with the op amp in a unity-gain configuration (no feedback resistor network, therefore no additional noise contributions). Two different op amps are shown with total circuit noise calculated. The OPA227 has very low voltage noise, making it ideal for low source impedances (less than 20kΩ). A similar precision op amp, the OPA277, has somewhat higher voltage noise but lower current noise. It provides excellent noise performance at moderate source impedance (10kΩ to 100kΩ). Above 100kΩ, a FET-input op amp such as the OPA132 (very low current noise) may provide improved performance. The equation is shown for the calculation of the total circuit noise. Note that en = voltage noise, in = current noise, RS = source impedance, k = Boltzmann’s constant = 1.38 • 10–23 J/K and T is temperature in K. For more details on calculating noise, see the insert titled “Basic Noise Calculations.” When the bias current is cancelled in this manner, the input bias current and input offset current are approximately equal. A resistor added to cancel the effect of the input bias current (as shown in Figure 3) may actually increase offset and noise and is therefore not recommended. Conventional Op Amp Configuration R2 R1 Not recommended for OPA227 RB = R2 || R1 Op Amp VOLTAGE NOISE SPECTRAL DENSITY vs SOURCE RESISTANCE External Cancellation Resistor Votlage Noise Spectral Density, E0 Typical at 1k (V/√Hz) 1.00+03 Recommended OPA227 Configuration R2 R1 OPA227 EO OPA227 RS 1.00E+02 OPA277 OPA277 Resistor Noise OPA227 1.00E+01 Resistor Noise EO2 = en2 + (in RS)2 + 4kTRS 1.00E+00 No cancellation resistor. See text. 100 1k 10k 100k 10M Source Resistance, RS (Ω) FIGURE 4. Noise Performance of the OPA227 in UnityGain Buffer Configuration. FIGURE 3. Input Bias Current Cancellation. BASIC NOISE CALCULATIONS noise component. The voltage noise is commonly modeled as a time-varying component of the offset voltage. The current noise is modeled as the time-varying component of the input bias current and reacts with the source resistance to create a voltage component of noise. Consequently, the lowest noise op amp for a given application depends on the source impedance. For low source impedance, current noise is negligible and voltage noise generally dominates. For high source impedance, current noise may dominate. Design of low noise op amp circuits requires careful consideration of a variety of possible noise contributors: noise from the signal source, noise generated in the op amp, and noise from the feedback network resistors. The total noise of the circuit is the root-sum-square combination of all noise components. The resistive portion of the source impedance produces thermal noise proportional to the square root of the resistance. This function is shown plotted in Figure 4. Since the source impedance is usually fixed, select the op amp and the feedback resistors to minimize their contribution to the total noise. Figure 5 shows both inverting and noninverting op amp circuit configurations with gain. In circuit configurations with gain, the feedback network resistors also contribute noise. The current noise of the op amp reacts with the feedback resistors to create additional noise components. The feedback resistor values can generally be chosen to make these noise sources negligible. The equations for total noise are shown for both configurations. Figure 4 shows total noise for varying source impedances with the op amp in a unity-gain configuration (no feedback resistor network and therefore no additional noise contributions). The operational amplifier itself contributes both a voltage noise component and a current ® OPA227, 2227, 4227 OPA228, 2228, 4228 12 Noise in Noninverting Gain Configuration R2 Noise at the output: 2 R R 2 2 E O 2 = 1 + 2 e n 2 + e12 + e 2 2 + (i n R 2 ) + e S 2 + (i n R S ) 1 + 2 R1 R1 R1 EO R2 2 R Where eS = √4kTRS • 1 + 2 = thermal noise of RS R1 RS VS R e1 = √4kTR1 • 2 R1 = thermal noise of R1 e2 = √4kTR2 = thermal noise of R2 Noise in Inverting Gain Configuration R2 Noise at the output: 2 R1 RS EO VS R2 2 2 2 2 2 E O 2 = 1 + e n + e1 + e 2 + (i n R 2 ) + e S R1 + R S R2 Where eS = √4kTRS • = thermal noise of RS R1 + R S R2 e1 = √4kTR1 • = thermal noise of R1 R1 + R S e2 = √4kTR2 = thermal noise of R2 For the OPA227 and OPA228 series op amps at 1kHz, en = 3nV/√Hz and in = 0.4pA/√Hz. FIGURE 5. Noise Calculation in Gain Configurations. 13 OPA227, 2227, 4227 OPA228, 2228, 4228 ® R1 2MΩ R2 2MΩ R8 402kΩ R11 178kΩ R3 1kΩ R4 9.09kΩ C4 22nF C6 10nF R6 40.2kΩ C1 1µF C2 1µF U1 R9 178kΩ 2 C3 0.47µF (OPA227) Input from Device Under Test R7 97.6kΩ 3 U2 R10 226kΩ 2 6 (OPA227) C5 0.47µF 3 U3 6 VOUT (OPA227) R5 634kΩ FIGURE 6. 0.1Hz to 10Hz Bandpass Filter Used to Test Wideband Noise of the OPA227 and OPA228 Series. USING THE OPA228 IN LOW GAINS The OPA228 family is intended for applications with signal gains of 5 or greater, but it is possible to take advantage of their high speed in lower gains. Without external compensation, the OPA228 has sufficient phase margin to maintain stability in unity gain with purely resistive loads. However, the addition of load capacitance can reduce the phase margin and destabilize the op amp. 22pF 100kΩ 10Ω 2 3 OPA227 6 A variety of compensation techniques have been evaluated specifically for use with the OPA228. The recommended configuration consists of an additional capacitor (CF) in parallel with the feedback resistance, as shown in Figures 8 and 11. This feedback capacitor serves two purposes in compensating the circuit. The op amp’s input capacitance and the feedback resistors interact to cause phase shift that can result in instability. CF compensates the input capacitance, minimizing peaking. Additionally, at high frequencies, the closed-loop gain of the amplifier is strongly influenced by the ratio of the input capacitance and the feedback capacitor. Thus, CF can be selected to yield good stability while maintaining high speed. VOUT Device Under Test FIGURE 7. Noise Test Circuit. Figure 6 shows the 0.1Hz 10Hz bandpass filter used to test the noise of the OPA227 and OPA228. The filter circuit was designed using Burr-Brown’s FilterPro software (available at www.burr-brown.com). Figure 7 shows the configuration of the OPA227 and OPA228 for noise testing. ® OPA227, 2227, 4227 OPA228, 2228, 4228 14 Without external compensation, the noise specification of the OPA228 is the same as that for the OPA227 in gains of 5 or greater. With the additional external compensation, the output noise of the of the OPA228 will be higher. The amount of noise increase is directly related to the increase in high frequency closed-loop gain established by the CIN/ CF ratio. values for CF. Because compensation is highly dependent on circuit design, board layout, and load conditions, CF should be optimized experimentally for best results. Figures 9 and 10 show the large- and small-signal step responses for the G = +2 configuration with 100pF load capacitance. Figures 12 and 13 show the large- and smallsignal step responses for the G = –2 configuration with 100pF load capacitance. Figures 8 and 11 show the recommended circuit for gains of +2 and –2, respectively. The figures suggest approximate 15pF 22pF 1kΩ 2kΩ 2kΩ 2kΩ OPA228 OPA228 2kΩ 2kΩ 100pF FIGURE 11. Compensation for OPA228 for G = –2. 25mV/div 25mV/div FIGURE 8. Compensation of the OPA228 for G =+2. 100pF OPA228 OPA228 400ns/div 400ns/div FIGURE 12. Large-Signal Step Response, G = –2, CLOAD = 100pF, Input Signal = 5Vp-p. 25mV/div 25mV/div FIGURE 9. Large-Signal Step Response, G = +2, CLOAD = 100pF, Input Signal = 5Vp-p. OPA228 OPA228 200ns/div 200ns/div FIGURE 10. Small-Signal Step Response, G = +2, CLOAD = 100pF, Input Signal = 50mVp-p. FIGURE 13. Small-Signal Step Response, G = –2, CLOAD = 100pF, Input Signal = 50mVp-p. 15 OPA227, 2227, 4227 OPA228, 2228, 4228 ® 1.1kΩ 1.43kΩ 2.2nF dc Gain = 1 330pF 1.1kΩ 1.65kΩ VIN 1.43kΩ 1.91kΩ OPA227 33nF 2.21kΩ OPA227 68nF VOUT 10nF fN = 13.86kHz fN = 20.33kHz Q = 1.186 Q = 4.519 f = 7.2kHz FIGURE 14. Three-Pole, 20kHz Low Pass, 0.5dB Chebyshev Filter. 20pF 0.1µF 100Ω TTL INPUT GAIN “1” “0” +1 –1 100kΩ 9.76kΩ 500Ω 2 3 OPA227 6 Output 10kΩ Input D1 Dexter 1M Thermopile Detector NOTE: Use metal film resistors and plastic film capacitor. Circuit must be well shielded to achieve low noise. D2 TTL In OPA227, 2227, 4227 OPA228, 2228, 4228 4.99kΩ S1 S2 3 6 OPA227 Output 8 1 4.75kΩ 1kΩ DG188 Offset Trim +VCC FIGURE 16. High Performance Synchronous Demodulator. FIGURE 15. Long-Wavelength Infrared Detector Amplifier. ® 2 4.75kΩ Responsivity ≈ 2.5 x 104V/W Output Noise ≈ 30µVrms, 0.1Hz to 10Hz Balance Trim 16 +15V 0.1µF 1kΩ 1kΩ Audio In 1/2 OPA2227 200Ω To Headphone 200Ω 1/2 OPA2227 This application uses two op amps in parallel for higher output current drive. 0.1µF –15V FIGURE 17. Headphone Amplifier. Bass Tone Control R1 7.5kΩ R2 50kΩ 3 R3 7.5kΩ 1 CW 2 R10 100kΩ Midrange Tone Control C1 940pF R4 2.7kΩ VIN R5 50kΩ 3 CW R6 2.7kΩ 1 2 C2 0.0047µF Treble Tone Control R7 7.5kΩ R8 50kΩ 3 CW R9 7.5kΩ 1 2 C3 680pF R11 100kΩ 2 3 OPA227 6 VOUT FIGURE 18. Three-Band ActiveTone Control (bass, midrange and treble). 17 OPA227, 2227, 4227 OPA228, 2228, 4228 ®