a Low-Noise, Precision Operational Amplifier OP27 PIN CONNECTIONS FEATURES Low Noise: 80 nV p-p (0.1 Hz to 10 Hz), 3 nV/÷Hz Low Drift: 0.2 V/C High Speed: 2.8 V/s Slew Rate, 8 MHz Gain Bandwidth Low VOS: 10 V Excellent CMRR: 126 dB at VCM of ±11 V High Open-Loop Gain: 1.8 Million Fits 725, OP07, 5534A Sockets Available in Die Form TO-99 (J-Suffix) BAL BAL 1 OP27 V+ OUT –IN 2 NC +IN 3 GENERAL DESCRIPTION 4V– (CASE) NC = NO CONNECT The OP27 precision operational amplifier combines the low offset and drift of the OP07 with both high speed and low noise. Offsets down to 25 mV and drift of 0.6 mV/∞C maximum make the OP27 ideal for precision instrumentation applications. Exceptionally low noise, en = 3.5 nV/÷Hz, at 10 Hz, a low 1/f noise corner frequency of 2.7 Hz, and high gain (1.8 million), allow accurate high-gain amplification of low-level signals. A gain-bandwidth product of 8 MHz and a 2.8 V/msec slew rate provides excellent dynamic accuracy in high-speed, dataacquisition systems. 8-Pin Hermetic DIP (Z-Suffix) Epoxy Mini-DIP (P-Suffix) 8-Pin SO (S-Suffix) A low input bias current of ± 10 nA is achieved by use of a bias-current-cancellation circuit. Over the military temperature range, this circuit typically holds IB and IOS to ±20 nA and 15 nA, respectively. VOS TRIM 1 The output stage has good load driving capability. A guaranteed swing of ± 10 V into 600 W and low output distortion make the OP27 an excellent choice for professional audio applications. OP27 8 VOS TRIM –IN 2 7 V+ +IN 3 6 OUT V– 4 5 NC NC = NO CONNECT (Continued on page 7) V+ R3 Q6 R1* 1 C2 R4 8 VOS ADJ. Q22 R2* R23 Q21 Q24 Q23 Q46 C1 R24 R9 Q20 Q1A Q1B Q2B Q19 OUTPUT R12 Q2A NONINVERTING INPUT (+) C3 R5 C4 Q3 INVERTING INPUT (–) Q11 Q26 Q12 Q27 Q45 Q28 *R1 AND R2 ARE PERMANENTLY ADJUSTED AT WAFER TEST FOR MINIMUM OFFSET VOLTAGE. V– Figure 1. Simplified Schematic 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 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., 2002 OP27–SPECIFICATIONS ELECTRICAL CHARACTERISTICS (@ V = ±15 V, T = 25C, unless otherwise noted.) S Conditions A Min OP27A/E Typ Max Min OP27F Typ Max Min OP27C/G Typ Max Parameter Symbol Unit INPUT OFFSET VOLTAGE1 VOS 10 25 20 60 30 100 mV LONG-TERM VOS STABILITY2, 3 VOS/Time 0.2 1.0 0.3 1.5 0.4 2.0 mV/MO INPUT OFFSET CURRENT IOS 7 35 9 50 12 75 nA INPUT BIAS CURRENT IB ± 10 ± 40 ± 12 ± 55 ± 15 ± 80 nA INPUT NOISE VOLTAGE3, 4 en p-p 0.1 Hz to 10 Hz 0.08 0.18 0.08 0.18 0.09 0.25 mV p-p INPUT NOISE Voltage Density3 en fO = 10 Hz fO = 30 Hz fO = 1000 Hz 3.5 3.1 3.0 5.5 4.5 3.8 3.5 3.1 3.0 5.5 4.5 3.8 3.8 3.3 3.2 8.0 5.6 4.5 nV/÷Hz nV/÷Hz nV/÷Hz INPUT NOISE Current Density3, 5 in fO = 10 Hz fO = 30 Hz fO = 1000 Hz 1.7 1.0 0.4 4.0 2.3 0.6 1.7 1.0 0.4 4.0 2.3 0.6 1.7 1.0 0.4 0.6 pA/÷Hz pA/÷Hz pA/÷Hz INPUT RESISTANCE Differential-Mode6 Common-Mode RIN RINCM 1.3 INPUT VOLTAGE RANGE IVR ± 11.0 ± 12.3 ± 11.0 ± 12.3 ± 11.0 ± 12.3 V 114 106 100 dB 6 3 0.94 5 2.5 0.7 4 2 MW GW COMMON-MODE REJECTION RATIO CMRR VCM = ± 11 V POWER SUPPLY PSRR REJECTION RATIO VS = ± 4 V to ± 18 V LARGE-SIGNAL VOLTAGE GAIN RL ≥ 2 kW, VO = ± 10 V RL ≥ 600 W, VO = ± 10 V 1000 1800 1000 1800 700 1500 V/mV 800 1500 800 1500 600 1500 V/mV AVO 126 1 10 123 1 10 120 2 20 mV/V OUTPUT VOLTAGE SWING VO RL ≥ 2 kW RL ≥ 600 W ± 12.0 ± 13.8 ± 10.0 ± 11.5 ± 12.0 ± 13.8 ± 10.0 ± 11.5 ± 11.5 ± 13.5 ± 10.0 ± 11.5 V V SLEW RATE7 SR RL ≥ 2 kW 1.7 2.8 1.7 2.8 1.7 2.8 V/ms GAIN BANDWIDTH PRODUCT7 GBW 5.0 8.0 5.0 8.0 5.0 8.0 MHz OPEN-LOOP OUTPUT RESISTANCE RO VO = 0, IO = 0 70 70 W POWER CONSUMPTION Pd VO 90 RP = 10 kW ± 4.0 OFFSET ADJUSTMENT RANGE 70 140 90 ± 4.0 140 100 ± 4.0 170 mW mV NOTES 1 Input offset voltage measurements are performed ~ 0.5 seconds after application of power. A/E grades guaranteed fully warmed up. 2 Long-term input offset voltage stability refers to the average trend line of V OS versus. Time over extended periods after the first 30 days of operation. Excluding the initial hour of operation, changes in V OS during the first 30 days are typically 2.5 mV. Refer to typical performance curve. 3 Sample tested. 4 See test circuit and frequency response curve for 0.1 Hz to 10 Hz tester. 5 See test circuit for current noise measurement. 6 Guaranteed by input bias current. 7 Guaranteed by design. –2– REV. B OP27 ELECTRICAL CHARACTERISTICS (@ VS = ±15 V, –55C £ TA £ 125C, unless otherwise noted.) Symbol INPUT OFFSET VOLTAGE1 VOS 30 60 TCVOS2 TCVOSn3 0.2 INPUT OFFSET CURRENT IOS INPUT BIAS CURRENT IB INPUT VOLTAGE RANGE IVR AVERAGE INPUT OFFSET DRIFT Conditions Min OP27A Typ Parameter Max Min OP27C Typ Max Unit 70 300 mV 0.6 4 1.8 mV/∞C 15 50 30 135 nA ± 20 ± 60 ± 35 ± 150 nA ± 10.3 ± 11.5 ± 10.2 ± 11.5 V 108 122 94 118 dB COMMON-MODE REJECTION RATIO CMRR VCM = ± 10 V POWER SUPPLY REJECTION RATIO PSRR VS = ± 4.5 V to ± 18 V 2 LARGE-SIGNAL VOLTAGE GAIN AVO RL ≥ 2 kW, VO = ± 10 V 600 1200 300 800 V/mV OUTPUT VOLTAGE SWING VO RL ≥ 2 kW ± 13.5 ± 10.5 ± 13.0 V ± 11.5 16 4 51 mV/V NOTES 1 Input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of power. A/E grades guaranteed fully warmed up. 2 The TCVOS performance is within the specifications unnulled or when nulled with R P = 8 kW to 20 kW. TCVOS is 100% tested for A/E grades, sample tested for C/F/G grades. 3 Guaranteed by design. REV. B –3– OP27 ELECTRICAL CHARACTERISTICS (@ VS = ±15 V, –25C¯£ TA £ 85C for OP27J, OP27Z, 0C £ TA £ 70C for OP27EP, OP27FP, and –40C £ TA £ 85C for OP27GP, OP27GS, unless otherwise noted.) VOS 20 50 40 140 55 220 mV TCVOS1 TCVOSn2 0.2 0.2 0.6 0.6 0.3 0.3 1.3 1.3 04 04 1.8 1.8 mV/∞C mV/∞C INPUT OFFSET CURRENT IOS 10 50 14 85 20 135 nA INPUT BIAS CURRENT IB ± 14 ± 60 ± 18 ± 95 ± 25 ± 150 nA INPUT VOLTAGE RANGE IVR POWER SUPPLY REJECTION RATIO PSRR LARGE-SIGNAL VOLTAGE GAIN OUTPUT VOLTAGE SWING AVO VO VCM = ± 10 V Max Min Min OP27G Typ Max INPUT ONSET VOLTAGE COMMON-MODE REJECTION RATIO CMRR Min OP27F Typ Max Symbol AVERAGE INPUT OFFSET DRIFT Conditions OP27E Typ Parameter Unit ± 10.5 ± 11.8 ± 10.5 ± 11.8 ± 10.5 ± 11.8 V 110 124 102 96 dB VS = ± 4.5 V to ± 18 V 2 15 121 2 RL ≥ 2 kW, VO = ± 10 V 750 1500 700 RL ≥ 2 kW ± 11.7 ± 13.6 ± 11.4 ± 13.5 1300 16 118 2 450 1000 ± 11.0 ± 13.3 32 mV/V V/mV V NOTES 1 The TCVOS performance is within the specifications unnulled or when nulled with R P = 8 kW to 20 kW. TCVOS is 100% tested for A/E grades, sample tested for C/F/G grades. 2 Guaranteed by design. –4– REV. B OP27 DICE CHARACTERISTICS 1. 2. 3. 4. 6. 7. 8. NULL (–) INPUT (+) INPUT V– OUTPUT V+ NULL DIE SIZE 0.109 0.055 INCH, 5995 SQ. MILS (2.77 1.40mm, 3.88 SQ. mm) WAFER TEST LIMITS (@ VS = ±15 V, TA = 25C unless otherwise noted.) OP27N Limit OP27G Limit OP27GR Limit Unit VOS 35 60 100 mV Max INPUT OFFSET CURRENT IOS 35 50 75 nA Max INPUT BIAS CURRENT IB ± 40 ± 55 ± 80 nA Max INPUT VOLTAGE RANGE IVR ± 11 ± 11 ± 11 V Min COMMON-MODE REJECTION RATIO CMRR VCM = IVR 114 106 100 dB Min POWER SUPPLY PSRR VS = ± 4 V to ± 18 V 10 10 20 mV/V Max AVO AVO RL ≥ 2 kW, VO = ± 10 V RL ≥ 600 W, VO = ± 10 V 1000 800 1000 800 700 600 V/mV Min V/mV Min OUTPUT VOLTAGE SWING VO VO RL ≥ 2 kW RL2600n ± 12.0 ± 10.0 ± 12.0 ± 10.0 +11.5 ± 10.0 V Min V Min POWER CONSUMPTION Pd VO = 0 140 140 170 mW Max Parameter Symbol INPUT OFFSET VOLTAGE* LARGE-SIGNAL VOLTAGE GAIN Conditions NOTE *Electrical tests are performed at wafer probe to the limits shown. Due to variations in assembly methods and normal yield loss, yield after packaging is not guaranteed for standard product dice. Consult factory to negotiate specifications based on dice lot qualification through sample lot assembly and testing. REV. B –5– OP27 TYPICAL ELECTRICAL CHARACTERISTICS (@ V = ±15 V, T = 25C unless otherwise noted.) S Parameter AVERAGE INPUT OFFSET VOLTAGE DRIFT* Symbol Conditions TCVOS or TCVOSn Nulled or Unnulled RP = 8 kW to 20 kW A OP27N Typical OP27G Typical OP27GR Typical Unit 0.2 0.3 0.4 mV/∞C AVERAGE INPUT OFFSET CURRENT DRIFT TCIOS 80 130 180 pA/∞C AVERAGE INPUT BIAS CURRENT DRIFT TCIB 100 160 200 pA/∞C INPUT NOISE VOLTAGE DENSITY en en en fO = 10 Hz fO = 30 Hz fO = 1000 Hz 3.5 3.1 3.0 3.5 3.1 3.0 3.8 3.3 3.2 nV/÷Hz nV/÷Hz nV/÷Hz in in in fO = 10 Hz fO = 30 Hz fO = 1000 Hz 1.7 1.0 0.4 1.7 1.0 0.4 1.7 1.0 0.4 pA/÷Hz pA/÷Hz pA/÷Hz INPUT NOISE VOLTAGE SLEW RATE enp-p SR 0.1 Hz to 10 Hz RL ≥ 2 kW 0.08 2.8 0.08 2.8 0.09 2.8 mV p-p V/ms GAIN BANDWIDTH PRODUCT GBW 8 8 8 MHz INPUT NOISE CURRENT DENSITY NOTE *Input offset voltage measurements are performed by automated test equipment approximately 0.5 seconds after application of power. –6– REV. B OP27 (Continued from page 1) The OP27 provides excellent performance in low-noise, highaccuracy amplification of low-level signals. Applications include stable integrators, precision summing amplifiers, precision voltagethreshold detectors, comparators, and professional audio circuits such as tape-head and microphone preamplifiers. PSRR and CMRR exceed 120 dB. These characteristics, coupled with long-term drift of 0.2 mV/month, allow the circuit designer to achieve performance levels previously attained only by discrete designs. The OP27 is a direct replacement for 725, OP06, OP07, and OP45 amplifiers; 741 types may be directly replaced by removing the 741’s nulling potentiometer. Low-cost, high-volume production of OP27 is achieved by using an on-chip Zener zap-trimming network. This reliable and stable offset trimming scheme has proved its effectiveness over many years of production history. ABSOLUTE MAXIMUM RATINGS 4 Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 22 V Input Voltage1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 22 V Output Short-Circuit Duration . . . . . . . . . . . . . . . . Indefinite Differential Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . ± 0.7 V Differential Input Current2 . . . . . . . . . . . . . . . . . . . . ± 25 mA Storage Temperature Range . . . . . . . . . . . . –65∞C to +150∞C Operating Temperature Range OP27A, OP27C (J, Z) . . . . . . . . . . . . . . . . –55∞C to +125∞C OP27E, OP27F (J, Z) . . . . . . . . . . . . . . . . . –25∞C to +85∞C OP27E, OP27F (P) . . . . . . . . . . . . . . . . . . . . . . 0∞C to 70∞C OP27G (P, S, J, Z) . . . . . . . . . . . . . . . . . . –40∞C to +85∞C Lead Temperature Range (Soldering, 60 sec) . . . . . . . 300∞C Junction Temperature . . . . . . . . . . . . . . . . . –65∞C to +150∞C Package Type JA3 JC Unit TO 99 (J) 8-Lead Hermetic DlP (Z) 8-Lead Plastic DIP (P) 20-Contact LCC (RC) 8-Lead SO (S) 150 148 103 98 158 18 16 43 38 43 ∞C/W ∞C/W ∞C/W ∞C/W ∞C/W NOTES 1 For supply voltages less than ± 22 V, the absolute maximum input voltage is equal to the supply voltage. 2 The OP27’s inputs are protected by back-to-back diodes. Current limiting resistors are not used in order to achieve low noise. If differential input voltage exceeds ± 0.7 V, the input current should be limited to 25 mA. 3 JA is specified for worst-case mounting conditions, i.e., JA is specified for device in socket for TO, CERDIP, and P-DIP packages; JA is specified for device soldered to printed circuit board for SO package. 4 Absolute Maximum Ratings apply to both DICE and packaged parts, unless otherwise noted. ORDERING INFORMATION 1 Package TA = 25∞C VOS Max (mV) 25 25 60 100 100 100 TO-99 CERDIP 8-Lead OP27AJ2, 3 OP27EJ2, 3 OP27AZ2 OP27EZ OP27GJ OP27CZ3 OP27GZ Plastic 8-Lead OP27EP OP27FP3 OP27GP OP27GS4 Operating Temperature Range MIL IND/COM IND/COM MIL XIND XIND NOTES 1 Burn-in is available on commercial and industrial temperature range parts in CERDIP, plastic DIP, and TO-can packages. 2 For devices processed in total compliance to MIL-STD-883, add /883 after part number. Consult factory for 883 data sheet. 3 Not for new design; obsolete April 2002. 4 For availability and burn-in information on SO and PLCC packages, contact your local sales office. 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 OP27 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. REV. B –7– WARNING! ESD SENSITIVE DEVICE OP27–Typical Performance Characteristics VOLTAGE NOISE – nV/ Hz 90 70 60 50 TEST TIME OF 10sec FURTHER LIMITS LOW FREQUENCY (<0.1Hz) GAIN 40 30 0.01 100 TA = 25C VS = 15V 5 4 3 I/F CORNER = 2.7Hz 2 I/F CORNER 10 I/F CORNER = LOW NOISE 2.7Hz AUDIO OP AMP OP27 I/F CORNER INSTRUMENTATION AUDIO RANGE RANGE TO DC TO 20kHz 1 0.1 1 10 FREQUENCY – Hz 1 1 100 TPC 1. 0.1 Hz to 10 Hzp-p Noise Tester Frequency Response 10 100 FREQUENCY – Hz 1k TPC 2. Voltage Noise Density vs. Frequency 1 TOTAL NOISE – nV/ Hz 1 0.1 1k 5 R1 TA = 25C VS = 15V TA = 25C VS = 15V 10 100 FREQUENCY – Hz TPC 3. A Comparison of Op Amp Voltage Noise Spectra 100 10 RMS VOLTAGE NOISE – V 741 VS = 15V R2 VOLTAGE NOISE – nV/ Hz GAIN – dB 80 10 9 8 7 6 VOLTAGE NOISE – nV/ Hz 100 RS – 2R1 10 AT 10Hz AT 1kHz 4 AT 10Hz 3 AT 1kHz 2 RESISTOR NOISE ONLY 1k 10k BANDWIDTH – Hz 1 100 100k TPC 4. Input Wideband Voltage Noise vs. Bandwidth (0.1 Hz to Frequency Indicated) 1 –50 10k TPC 5. Total Noise vs. Sourced Resistance 4 AT 10Hz AT 1kHz 3 2 0 10 20 30 40 1.0 TOTAL SUPPLY VOLTAGE (V+ – V–) – V TPC 7. Voltage Noise Density vs. Supply Voltage 0.1 10 0 25 50 75 TEMPERATURE – C 100 125 5.0 4.0 TA = +125C 3.0 TA = –55C 2.0 TA = +25C I/F CORNER = 140Hz 1 –25 TPC 6. Voltage Noise Density vs. Temperature 10.0 TA = 25C CURRENT NOISE – pA/ Hz VOLTAGE NOISE – nV/ Hz 5 1k SOURCE RESISTANCE – SUPPLY CURRENT – mA 0.01 100 1.0 100 1k FREQUENCY – Hz 10k TPC 8. Current Noise Density vs. Frequency –8– 5 15 25 35 TOTAL SUPPLY VOLTAGE – V 45 TPC 9. Supply Current vs. Supply Voltage REV. B OP27 10 OP27A 0 –10 OP27A –20 –30 –40 TRIMMING WITH 10k POT DOES NOT CHANGE TCVOS –50 –60 –70 –75 –50 –25 2 0 –2 –4 –6 6 4 2 0 –2 –4 OP27C 0 1 2 3 4 5 THERMAL SHOCK RESPONSE BAND DEVICE IMMERSED IN 70C OIL BATH 40 60 40 30 20 OP27C 10 80 –50 –25 100 90 70 50 SLEW RATE – V/s VOLTAGE GAIN – dB 110 30 10 10 100 1k 10k 100k 1M 10M 100M FREQUENCY – Hz TPC 16. Open-Loop Gain vs. Frequency REV. B 20 OP27C 10 OP27A 0 25 50 75 0 –75 –50 100 125 150 TPC 14. Input Bias Current vs. Temperature PHASE MARGIN – Degrees 130 5 30 TEMPERATURE – C TPC 13. Offset Voltage Change Due to Thermal Shock 4 3 40 OP27A TIME – Sec 1 2 VS = 15V –25 0 25 50 75 TEMPERATURE – C 100 125 TPC 15. Input Offset Current vs. Temperature 25 80 70 M VS = 15V 9 60 GBW 50 8 4 SLEW 3 7 2 –75 –50 –25 0 25 50 75 6 100 125 TEMPERATURE – C TPC 17. Slew Rate, Gain-Bandwidth Product, Phase Margin vs. Temperature –9– TA = 25C VS = 15V 10 20 100 GAIN 120 15 GAIN – dB 20 1 50 GAIN BANDWIDTH PRODUCT – MHz 0 0 TPC 12. Warm-Up Offset Voltage Drift 0 0 –20 OP27 A/E TIME AFTER POWER ON – Min INPUT OFFSET CURRENT – nA INPUT BIAS CURRENT – nA OPEN-LOOP GAIN – dB 15 5 OP27 F 5 VS = 15V TA = 70C 10 OP27 C/G 7 50 25 –10 6 TPC 11. Long-Term Offset Voltage Drift of Six Representative Units VS = 15V 20 10 TIME – Months 30 TA = 25C TA = 25C VS = 15V 1 –6 0 25 50 75 100 125 150 175 TEMPERATURE – C TPC 10. Offset Voltage Drift of Five Representative Units vs. Temperature 4 10 PHASE MARGIN = 70 140 5 160 0 180 –5 200 –10 1M 10M FREQUENCY – Hz TPC 18. Gain, Phase Shift vs. Frequency 220 100M PHASE SHIFT – Degrees OP27A 30 20 CHANGE IN OFFSET VOLTAGE – V 40 OFFSET VOLTAGE – V 6 OP27C 50 CHANGE IN INPUT OFFSET VOLTAGE – V 60 OP27 2.5 18 28 TA = 25C VS = 15V 2.0 RL = 2k 1.5 RL = 1k 1.0 0.5 0 0 10 20 30 40 24 20 16 12 8 12 NEGATIVE SWING 10 8 6 4 2 4 TA = 25C VS = 15V 0 10k TOTAL SUPPLY VOLTAGE – V TPC 19. Open-Loop Voltage Gain vs. Supply Voltage POSITIVE SWING 14 0 1k 50 16 MAXIMUM OUTPUT – V PEAK-TO-PEAK AMPLITUDE – V OPEN-LOOP GAIN – V/V TA = 25C 100k 1M FREQUENCY – Hz –2 100 10M TPC 20. Maximum Output Swing vs. Frequency 1k LOAD RESISTANCE – 10k TPC 21. Maximum Output Voltage vs. Load Resistance 100 VS = 15V VIN = 100mV AV = +1 80 500ns 20mV % OVERSHOOT 50mV 60 0V 2s 2V +5V AVCL = +1 CL = 15pF VS = 15V TA = 25C AVCL = +1 VS = 15V TA = 25C 0V 40 –5V –50mV 20 0 0 500 1000 1500 2000 2500 CAPACITIVE LOAD – pF TPC 22. Small-Signal Overshoot vs. Capacitive Load TPC 23. Small-Signal Transient Response 140 60 16 VS = 15V TA = 25C VCM = 10V 50 120 40 ISC(+) 30 TA = –55C 12 COMMON-MODE RANGE – V TA = 25C VS = 15V CMRR – dB SHORT-CIRCUIT CURRENT – mA TPC 24. Large-Signal Transient Response 100 ISC(–) 80 20 TA = +25C 8 TA = +125C 4 0 TA = –55C –4 TA = +25C –8 TA = +125C –12 10 0 1 2 3 4 TIME FROM OUTPUT SHORTED TO GROUND – Min TPC 25. Short-Circuit Current vs. Time 5 60 100 –16 1k 10k 100k FREQUENCY – Hz TPC 26. CMRR vs. Frequency –10– 1M 0 5 10 15 20 SUPPLY VOLTAGE – V TPC 27. Common-Mode Input Range vs. Supply Voltage REV. B OP27 2.4 OP27 10 D.U.T. VOLTAGE GAIN = 50,000 4.7F 2k 4.3k 22F OP12 100k 0.1F 2.2F 24.3k SCOPE 1 RIN = 1M 110k TPC 28. Voltage Noise Test Circuit (0.1 Hz to 10 Hz) TA = 25C VS = 15V 2.2 1 SEC/DIV 2.0 120 VOLTAGE NOISE – nV 100k OPEN-LOOP VOLTAGE GAIN – V/V 0.1F 1.8 1.6 1.4 1.2 1.0 80 40 0 –40 –90 –120 0.8 0.6 0.1Hz to 10Hz p-p NOISE 0.4 100 1k 10k LOAD RESISTANCE – 100k TPC 29. Open-Loop Voltage Gain vs. Load Resistance TPC 30. Low-Frequency Noise POWER SUPPLY REJECTION RATIO – dB 160 TA = 25C 140 120 100 NEGATIVE SWING 80 60 POSITIVE SWING 40 20 0 1 10 100 1k 10k 100k 1M 10M 100M FREQUENCY – Hz TPC 31. PSRR vs. Frequency APPLICATION INFORMATION OP27 series units may be inserted directly into 725 and OP07 sockets with or without removal of external compensation or nulling components. Additionally, the OP27 may be fitted to unnulled 741-type sockets; however, if conventional 741 nulling circuitry is in use, it should be modified or removed to ensure correct OP27 operation. OP27 offset voltage may be nulled to zero (or another desired setting) using a potentiometer (see Offset Nulling Circuit). approximately (VOS/300) mV/∞C. For example, the change in TCVOS will be 0.33 mV/∞C if VOS is adjusted to 100 mV. The offset voltage adjustment range with a 10 kW potentiometer is ± 4 mV. If smaller adjustment range is required, the nulling sensitivity can be reduced by using a smaller pot in conjuction with fixed resistors. For example, the network below will have a ± 280 mV adjustment range. 1 The OP27 provides stable operation with load capacitances of up to 2000 pF and ± 10 V swings; larger capacitances should be decoupled with a 50 W resistor inside the feedback loop. The OP27 is unity-gain stable. Thermoelectric voltages generated by dissimilar metals at the input terminal contacts can degrade the drift performance. Best operation will be obtained when both input contacts are maintained at the same temperature. OFFSET VOLTAGE ADJUSTMENT The input offset voltage of the OP27 is trimmed at wafer level. However, if further adjustment of VOS is necessary, a 10 kW trim potentiometer can be used. TCVOS is not degraded (see Offset Nulling Circuit). Other potentiometer values from 1 kW to 1 MW can be used with a slight degradation (0.1 mV/∞C to 0.2 mV/∞C) of TCVOS. Trimming to a value other than zero creates a drift of REV. B 4.7k 1k POT 4.7k 8 V+ Figure 2. NOISE MEASUREMENTS To measure the 80 nV peak-to-peak noise specification of the OP27 in the 0.1 Hz to 10 Hz range, the following precautions must be observed: 1. The device must be warmed up for at least five minutes. As shown in the warm-up drift curve, the offset voltage typically changes 4 mV due to increasing chip temperature after power-up. In the 10-second measurement interval, these temperature-induced effects can exceed tens-ofnanovolts. 2. For similar reasons, the device has to be well-shielded from air currents. Shielding minimizes thermocouple effects. –11– OP27 3. Sudden motion in the vicinity of the device can also “feedthrough” to increase the observed noise. 1/2 È(Voltage Noise)2 + ˘ Í ˙ 2 Í ˙ Total Noise = Í(Current Noise ¥ RS ) + ˙ Í ˙ 2 ÍÎ(Resistor Noise) ˙˚ 4. The test time to measure 0.1 Hz to 10 Hz noise should not exceed 10 seconds. As shown in the noise-tester frequency response curve, the 0.1 Hz corner is defined by only one zero. The test time of 10 seconds acts as an additional zero to eliminate noise contributions from the frequency band below 0.1 Hz. Figure 4 shows noise versus source-resistance at 1000 Hz. The same plot applies to wideband noise. To use this plot, multiply the vertical scale by the square root of the bandwidth. 5. A noise-voltage-density test is recommended when measuring noise on a large number of units. A 10 Hz noise-voltagedensity measurement will correlate well with a 0.1 Hz to 10 Hz peak-to-peak noise reading, since both results are determined by the white noise and the location of the 1/f corner frequency. 100 50 TOTAL NOISE – nV/ Hz 1 UNITY-GAIN BUFFER APPLICATIONS When R f £ 100 W and the input is driven with a fast, large signal pulse (>1 V), the output waveform will look as shown in the pulsed operation diagram (Figure 3). During the fast feedthrough-like portion of the output, the input protection diodes effectively short the output to the input and a current, limited only by the output short-circuit protection, will be drawn by the signal generator. With Rf ≥ 500 W, the output is capable of handling the current requirements (IL £ 20 mA at 10 V); the amplifier will stay in its active mode and a smooth transition will occur. Rf – 2.8V/s OP27 + Figure 3. Pulsed Operation COMMENTS ON NOISE The OP27 is a very low-noise monolithic op amp. The outstanding input voltage noise characteristics of the OP27 are achieved mainly by operating the input stage at a high quiescent current. The input bias and offset currents, which would normally increase, are held to reasonable values by the input bias-current cancellation circuit. The OP27A/E has IB and IOS of only ± 40 nA and 35 nA at 25∞C respectively. This is particularly important when the input has a high source resistance. In addition, many audio amplifier designers prefer to use direct coupling. The high IB, VOS, and TCVOS of previous designs have made direct coupling difficult, if not impossible, to use. 2 OP07 10 5 1 RS e.g. RS 2 RS e.g. RS 5534 OP27/37 1 50 UNMATCHED = R S1 = 10k, R S2 = 0 MATCHED = 10k, R S1 = R S2 = 5k RS1 RS2 REGISTER NOISE ONLY 10k 500 1k 5k RS – SOURCE RESISTANCE – 100 50k Figure 4. Noise vs. Source Resistance (Including Resistor Noise) at 1000 Hz At RS <1 kW, the OP27’s low voltage noise is maintained. With RS <1 kW, total noise increases, but is dominated by the resistor noise rather than current or voltage noise. lt is only beyond RS of 20 kW that current noise starts to dominate. The argument can be made that current noise is not important for applications with low to moderate source resistances. The crossover between the OP27, OP07, and OP08 noise occurs in the 15 kW to 40 kW region. Figure 5 shows the 0.1 Hz to 10 Hz peak-to-peak noise. Here the picture is less favorable; resistor noise is negligible and current noise becomes important because it is inversely proportional to the square root of frequency. The crossover with the OP07 occurs in the 3 kW to 5 kW range depending on whether balanced or unbalanced source resistors are used (at 3 kW the IB and IOS error also can be three times the VOS spec.). Voltage noise is inversely proportional to the square root of bias current, but current noise is proportional to the square root of bias current. The OP27’s noise advantage disappears when high source-resistors are used. Figures 4, 5, and 6 compare OP27’s observed total noise with the noise performance of other devices in different circuit applications. 1k OP08/108 500 5534 OP07 p-p NOISE – nV When Rf > 2 kW, a pole will be created with Rf and the amplifier’s input capacitance (8 pF) that creates additional phase shift and reduces phase margin. A small capacitor (20 pF to 50 pF) in parallel with R f will eliminate this problem. OP08/108 1 2 100 OP27/37 1 RS e.g. RS 2 RS e.g. RS 50 UNMATCHED = R S1 = 10k, R S2 = 0 MATCHED = 10k, R S1 = R S2 = 5k RS1 REGISTER NOISE ONLY 10 50 100 RS2 10k 500 1k 5k RS – SOURCE RESISTANCE – 50k Figure 5. Peak-to-Peak Noise (0.1 Hz to 10 Hz) as Source Resistance (Includes Resistor Noise) –12– REV. B OP27 Therefore, for low-frequency applications, the OP07 is better than the OP27/OP37 when RS > 3 kW. The only exception is when gain error is important. Figure 6 illustrates the 10 Hz noise. As expected, the results are between the previous two figures. For reference, typical source resistances of some signal sources are listed in Table I. Table I. Device Source Impedance Strain Gauge <500 W Typically used in lowfrequency applications. Magnetic Tapehead <1500 W Low is very important to reduce self-magnetization problems when direct coupling is used. OP27 IB can be neglected. <1500 W Magnetic Phonograph Cartridges Linear Variable <1500 W Differential Transformer Comments Figure 7 is an example of a phono pre-amplifier circuit using the OP27 for A1; R1-R2-C1-C2 form a very accurate RIAA network with standard component values. The popular method to accomplish RIAA phono equalization is to employ frequencydependent feedback around a high-quality gain block. Properly chosen, an RC network can provide the three necessary time constants of 3180, 318, and 75 ms.1 For initial equalization accuracy and stability, precision metal film resistors and film capacitors of polystyrene or polypropylene are recommended since they have low voltage coefficients, dissipation factors, and dielectric absorption.4 (High-K ceramic capacitors should be avoided here, though low-K ceramics— such as NPO types, which have excellent dissipation factors and somewhat lower dielectric absorption—can be considered for small values.) C4 (2) 220F + + MOVING MAGNET CARTRIDGE INPUT Similar need for low IB in direct coupled applications. OP27 will not introduce any self-magnetization problem. Ra 47.5k Ca 150pF C3 0.47F A1 OP27 R1 97.6k Used in rugged servo-feedback applications. Bandwidth of interest is 400 Hz to 5 kHz. R2 7.87k OP07 OP27 OP37 3 Hz 10 Hz 30 Hz 100 dB 100 dB 90 dB 124 dB 120 dB 110 dB 125 dB 125 dB 124 dB For further information regarding noise calculations, see “Minimization of Noise in Op Amp Applications,” Application Note AN-15. 100 50 1 TOTAL NOISE – nV/ Hz 2 1 RS e.g. RS 2 RS e.g. RS OP27/37 UNMATCHED = R S1 = 10k, R S2 = 0 MATCHED = 10k, R S1 = R S2 = 5k RS1 REGISTER NOISE ONLY RS2 10k 500 1k 5k RS – SOURCE RESISTANCE – 50k Figure 6. 10 Hz Noise vs. Source Resistance (Includes Resistor Noise) AUDIO APPLICATIONS The following applications information has been abstracted from a PMI article in the 12/20/80 issue of Electronic Design magazine and updated. REV. B C2 0.01F Figure 7. The OP27 brings a 3.2 nV/÷Hz voltage noise and 0.45 pA/÷Hz current noise to this circuit. To minimize noise from other sources, R3 is set to a value of 100 W, which generates a voltage noise of 1.3 nV/÷Hz. The noise increases the 3.2 nV/÷Hz of the amplifier by only 0.7 dB. With a 1 kW source, the circuit noise measures 63 dB below a 1 mV reference level, unweighted, in a 20 kHz noise bandwidth. Ê R1 ˆ G = 0.101 Á1 + ˜ Ë R3 ¯ 5534 100 OUTPUT C1 0.03F G = 1kHz GAIN R1 = 0.101 ( 1 + ) R3 = 98.677 (39.9dB) AS SHOWN OP07 5 1 50 R4 75k IN Gain (G) of the circuit at 1 kHz can be calculated by the expression: OP08/108 10 LF ROLLOFF OUT R3 100 Open-Loop Gain Frequency at R5 100k For the values shown, the gain is just under 100 (or 40 dB). Lower gains can be accommodated by increasing R3, but gains higher than 40 dB will show more equalization errors because of the 8 MHz gain-bandwidth of the OP27. This circuit is capable of very low distortion over its entire range, generally below 0.01% at levels up to 7 V rms. At 3 V output levels, it will produce less than 0.03% total harmonic distortion at frequencies up to 20 kHz. Capacitor C3 and resistor R4 form a simple –6 dB-per-octave rumble filter, with a corner at 22 Hz. As an option, the switchselected shunt capacitor C4, a nonpolarized electrolytic, bypasses the low-frequency rolloff. Placing the rumble filter’s high-pass action after the preamp has the desirable result of discriminating –13– OP27 noise. The rms sum of these predominant noise sources will be about 6 nV/÷Hz, equivalent to 0.9 mV in a 20 kHz noise bandwidth, or nearly 61 dB below a 1 mV input signal. Measurements confirm this predicted performance. against the RlAA-amplified low-frequency noise components and pickup-produced low-frequency disturbances. A preamplifier for NAB tape playback is similar to an RIAA phono preamp, though more gain is typically demanded, along with equalization requiring a heavy low-frequency boost. The circuit in Figure 7 can be readily modified for tape use, as shown by Figure 8. Ra Ca R3 316k C1 5F R6 100 – + TAPE HEAD R1 1k LOW IMPEDANCE MICROPHONE INPUT (Z = 50 TO 200 ) 0.47F OP27 – R1 33k R2 5k OP27/ Rp 30k OP37 R7 10k OUTPUT + 15k R2 1k R3 = R4 R1 R2 R4 316k 0.01F 10 Figure 9. T1 = 3180s T2 = 50s Figure 8. While the tape-equalization requirement has a flat high-frequency gain above 3 kHz (T2 = 50 ms), the amplifier need not be stabilized for unity gain. The decompensated OP37 provides a greater bandwidth and slew rate. For many applications, the idealized time constants shown may require trimming of R1 and R2 to optimize frequency response for nonideal tapehead performance and other factors.5 For applications demanding appreciably lower noise, a high quality microphone transformer-coupled preamp (Figure 10) incorporates the internally compensated OP27. T1 is a JE-115K-E 150 W/15 kW transformer which provides an optimum source resistance for the OP27 device. The circuit has an overall gain of 40 dB, the product of the transformer’s voltage setup and the op amp’s voltage gain. C2 1800pF R1 121 The network values of the configuration yield a 50 dB gain at 1 kHz, and the dc gain is greater than 70 dB. Thus, the worst-case output offset is just over 500 mV. A single 0.47 mF output capacitor can block this level without affecting the dynamic range. R2 1100 A1 OP27 T1* The tapehead can be coupled directly to the amplifier input, since the worst-case bias current of 80 nA with a 400 mH, 100 m inch head (such as the PRB2H7K) will not be troublesome. 150 SOURCE R3 100 OUTPUT * T1 – JENSEN JE – 115K – E JENSEN TRANSFORMERS 10735 BURBANK BLVD. N. HOLLYWOOD, CA 91601 One potential tapehead problem is presented by amplifier biascurrent transients which can magnetize a head. The OP27 and OP37 are free of bias-current transients upon power-up or powerdown. However, it is always advantageous to control the speed of power supply rise and fall, to eliminate transients. Figure 10. Gain may be trimmed to other levels, if desired, by adjusting R2 or R1. Because of the low offset voltage of the OP27, the output offset of this circuit will be very low, 1.7 mV or less, for a 40 dB gain. The typical output blocking capacitor can be eliminated in such cases, but is desirable for higher gains to eliminate switching transients. In addition, the dc resistance of the head should be carefully controlled, and preferably below 1 kS2. For this configuration, the bias-current-induced offset voltage can be greater than the 100pV maximum offset if the head resistance is not sufficiently controlled. +18V A simple, but effective, fixed-gain transformerless microphone preamp ( Figure 9) amplifies differential signals from low impedance microphones by 50 dB, and has an input impedance of 2 kW. Because of the high working gain of the circuit, an OP37 helps to preserve bandwidth, which will be 110 kHz. As the OP37 is a decompensated device (minimum stable gain of 5), a dummy resistor, Rp, may be necessary, if the microphone is to be unplugged. Otherwise the 100% feedback from the open input may cause the amplifier to oscillate. OP27 –18V Figure 11. Burn-In Circuit Common-mode input-noise rejection will depend upon the match of the bridge-resistor ratios. Either close-tolerance (0.1%) types should be used, or R4 should be trimmed for best CMRR. All resistors should be metal film types for best stability and low noise. Noise performance of this circuit is limited more by the input resistors R1 and R2 than by the op amp, as R1 and R2 each generate a 4 nV/÷Hz noise, while the op amp generates a 3.2 nV/÷Hz Capacitor C2 and resistor R2 form a 2 ms time constant in this circuit, as recommended for optimum transient response by the transformer manufacturer. With C2 in use, A1 must have unitygain stability. For situations where the 2 ms time constant is not necessary, C2 can be deleted, allowing the faster OP37 to be employed. –14– REV. B OP27 Some comment on noise is appropriate to understand the capability of this circuit. A 150 Ω resistor and R1 and R2 gain resistors connected to a noiseless amplifier will generate 220 nV of noise in a 20 kHz bandwidth, or 73 dB below a 1 mV reference level. Any practical amplifier can only approach this noise level; it can never exceed it. With the OP27 and T1 specified, the additional noise degradation will be close to 3.6 dB (or –69.5 referenced to 1 mV). V+ OP27 1. Lipshitz, S.R, “On RIAA Equalization Networks,” JAES, Vol. 27, June 1979, p. 458–481. 2. Jung, W.G., IC Op Amp Cookbook, 2nd. Ed., H.W. Sams and Company, 1980. 3. Jung, W.G., Audio IC Op Amp Applications, 2nd. Ed., H.W. Sams and Company, 1978. 4. Jung, W.G., and Marsh, R.M., “Picking Capacitors,” Audio, February and March, 1980. RP 10k⍀ INPUT References 5. Otala, M., “Feedback-Generated Phase Nonlinearity in Audio Amplifiers,” London AES Convention, March 1980, preprint 1976. OUTPUT 6. Stout, D.F., and Kautman, M., Handbook of Operational Amplifier Circuit Design, New York, McGraw-Hill, 1976. V– Figure 12. Offset Nulling Circuit OUTLINE DIMENSIONS 8-LeadPlastic Dual-in-Line Package [PDIP] 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) (N-8) Dimensions shown in inches and (millimeters) Dimensions shown in millimeters and (inches) 0.375 (9.53) 0.365 (9.27) 0.355 (9.02) 8 1 5 4 5.00 (0.1968) 4.80 (0.1890) 0.295 (7.49) 0.285 (7.24) 0.275 (6.98) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.100 (2.54) BSC 0.180 (4.57) MAX 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 4.00 (0.1574) 3.80 (0.1497) 0.015 (0.38) MIN SEATING PLANE 0.060 (1.52) 0.050 (1.27) 0.045 (1.14) 0.150 (3.81) 0.135 (3.43) 0.120 (3.05) 5 1 4 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 0.015 (0.38) 0.010 (0.25) 0.008 (0.20) COPLANARITY SEATING 0.10 PLANE 6.20 (0.2440) 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.33 (0.0130) 0.50 (0.0196) ⴛ 45ⴗ 0.25 (0.0099) 8ⴗ 0.25 (0.0098) 0ⴗ 1.27 (0.0500) 0.41 (0.0160) 0.19 (0.0075) COMPLIANT TO JEDEC STANDARDS MS-012AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN COMPLIANT TO JEDEC STANDARDS MO-095AA CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS (IN PARENTHESES) REV. B 8 –15– 8-Lead Ceramic Dip – Glass Hermetic Seal [CERDIP] (Q-8) 8-Lead Metal Can [TO-99] (H-08) Dimensions shown in inches and (millimeters) Dimensions shown in inches and (millimeters) 0.005 (0.13) MIN 8 0.055 (1.40) MAX REFERENCE PLANE 0.1850 (4.70) 0.1650 (4.19) 5 0.310 (7.87) 0.220 (5.59) PIN 1 1 C00317–0–9/02(B) OUTLINE DIMENSIONS 0.5000 (12.70) MIN 0.2500 (6.35) MIN 0.1000 (2.54) BSC 0.0500 (1.27) MAX 0.1600 (4.06) 0.1400 (3.56) 4 0.060 (1.52) 0.015 (0.38) 0.200 (5.08) MAX 0.150 (3.81) MIN 0.200 (5.08) 0.125 (3.18) 0.023 (0.58) 0.014 (0.36) 0.3350 (8.51) 0.3050 (7.75) 0.320 (8.13) 0.290 (7.37) 0.405 (10.29) MAX 0.3700 (9.40) 0.3350 (8.51) 5 0.100 (2.54) BSC SEATING 0.070 (1.78) PLANE 0.030 (0.76) 15 0 0.015 (0.38) 0.008 (0.20) 0.0400 (1.02) MAX 0.0400 (1.02) 0.0100 (0.25) CONTROLLING DIMENSIONS ARE IN INCH; MILLIMETERS DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN 6 4 0.2000 (5.08) BSC 3 7 2 0.0190 (0.48) 0.0160 (0.41) 0.1000 (2.54) BSC 0.0210 (0.53) 0.0160 (0.41) 0.0450 (1.14) 0.0270 (0.69) 8 1 0.0340 (0.86) 0.0280 (0.71) 45 BSC BASE & SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-002AK CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Revision History Location Page 9/02—Data Sheet changed from REV. A to REV. B. Edits to Figure 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Edits to OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9/01—Data Sheet changed from REV. 0 to REV. A. Edits to ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Edits to PIN CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Edits to PACKAGE TYPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Edits to ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 3 Edits to WAFER TEST LIMITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Deleted TYPICAL ELECTRICAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Edits to BURN-IN CIRCUIT figure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Edits to APPLICATION INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 –16– PRINTED IN U.S.A. Edits to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2