OP A1 611 OP A1 612 OPA1611 OPA1612 Burr-Brown Audio www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 ™ High-Performance, Bipolar-Input AUDIO OPERATIONAL AMPLIFIERS Check for Samples: OPA1611 OPA1612 FEATURES DESCRIPTION • • • The OPA1611 (single) and OPA1612 (dual) bipolar-input operational amplifiers achieve very low 1.1nV/√Hz noise density with an ultralow distortion of 0.000015% at 1kHz. The OPA1611 and OPA1612 offer rail-to-rail output swing to within 600mV with a 2kΩ load, which increases headroom and maximizes dynamic range. These devices also have a high output drive capability of ±30mA. 1 23 • • • • • • • • SUPERIOR SOUND QUALITY ULTRALOW NOISE: 1.1nV/√Hz at 1kHz ULTRALOW DISTORTION: 0.000015% AT 1kHz HIGH SLEW RATE: 27V/μs WIDE BANDWIDTH: 40MHz (G = +1) HIGH OPEN-LOOP GAIN: 130dB UNITY GAIN STABLE LOW QUIESCENT CURRENT: 3.6mA (Single), 7.2mA (Dual) RAIL-TO-RAIL OUTPUT WIDE SUPPLY RANGE: ±2.25V to ±18V SINGLE AND DUAL VERSIONS AVAILABLE These devices operate over a very wide supply range of ±2.25V to ±18V, on only 3.6mA of supply current per channel. The OPA1611 and OPA1612 op amps are unity-gain stable and provide excellent dynamic behavior over a wide range of load conditions. The dual version features completely independent circuitry for lowest crosstalk and freedom from interactions between channels, even when overdriven or overloaded. APPLICATIONS • • • • • • Both the OPA1611 and OPA1612 are available in SO-8 packages and are specified from –40°C to +85°C. SoundPlus ™ PROFESSIONAL AUDIO EQUIPMENT MICROPHONE PREAMPLIFIERS ANALOG AND DIGITAL MIXING CONSOLES BROADCAST STUDIO EQUIPMENT AUDIO TEST AND MEASUREMENT HIGH-END A/V RECEIVERS V+ Pre-Output Driver IN- OUT IN+ V- 1 2 3 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. SoundPlus is a trademark of Texas Instruments Incorporated. All other trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2009, Texas Instruments Incorporated OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments 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. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range (unless otherwise noted). Supply Voltage VS = (V+) – (V–) Input Voltage VALUE UNIT 40 V (V–) – 0.5 to (V+) + 0.5 V ±10 mA Input Current (All pins except power-supply pins) Output Short-Circuit (2) Continuous Operating Temperature (TA) –55 to +125 °C Storage Temperature (TA) –65 to +150 °C Junction Temperature (TJ) ESD Ratings (1) (2) 200 °C Human Body Model (HBM) 3000 V Charged Device Model (CDM) 1000 V Machine Model (MM) 200 V Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not supported. Short-circuit to VS/2 (ground in symmetrical dual supply setups), one amplifier per package. PACKAGE INFORMATION (1) (1) PRODUCT PACKAGE-LEAD PACKAGE DESIGNATOR PACKAGE MARKING OPA1611 SO-8 D TI OPA 1611A OPA1612 SO-8 D TI OPA 1612A For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. PIN CONFIGURATIONS D PACKAGE OPA1611, SO-8 (TOP VIEW) NC (1) (1) D PACKAGE OPA1612, SO-8 (TOP VIEW) (1) 1 8 NC -IN 2 7 V+ +IN 3 6 OUT V- 4 5 NC OUT A -IN A 1 2 +IN A 3 V- 4 A B 8 V+ 7 OUT B 6 -IN B 5 +IN B (1) NC denotes no internal connection. Pin can be left floating or connected to any voltage between (V–) and (V+). 2 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 ELECTRICAL CHARACTERISTICS: VS = ±2.25V to ±18V At TA = +25°C and RL = 2kΩ, unless otherwise noted. VCM = VOUT = midsupply, unless otherwise noted. Boldface limits apply over the specified temperature range, TA = –40°C to +85°C. OPA1611AI, OPA1612AI PARAMETER CONDITIONS MIN TYP MAX UNIT AUDIO PERFORMANCE Total Harmonic Distortion + Noise Intermodulation Distortion THD+N G = +1, f = 1kHz, VO = 3VRMS IMD 0.000015 % –136 dB G = +1, VO = 3VRMS SMPTE/DIN Two-Tone, 4:1 (60Hz and 7kHz) DIM 30 (3kHz square wave and 15kHz sine wave) 0.000015 % –136 dB 0.000012 % –138 dB 0.000008 % –142 dB G = 100 80 MHz G=1 40 MHz G = –1 27 V/μs VO = 1VPP 4 MHz CCIF Twin-Tone (19kHz and 20kHz) FREQUENCY RESPONSE Gain-Bandwidth Product Slew Rate GBW SR Full Power Bandwidth (1) Overload Recovery Time G = –10 500 ns Channel Separation (Dual) f = 1kHz –130 dB f = 20Hz to 20kHz 1.2 μVPP f = 10Hz 2 nV/√Hz f = 100Hz 1.5 nV/√Hz f = 1kHz 1.1 nV/√Hz f = 10Hz 3 pA/√Hz f = 1kHz 1.7 pA/√Hz VS = ±15V ±100 ±500 μV 1 4 μV/°C VS = ±2.25V to ±18V 0.1 1 μV/V VCM = 0V ±60 ±250 nA 350 nA ±175 nA (V+) – 2 V NOISE Input Voltage Noise Input Voltage Noise Density Input Current Noise Density en In OFFSET VOLTAGE Input Offset Voltage over Temperature (2) vs Power Supply VOS dVOS/dT PSRR INPUT BIAS CURRENT Input Bias Current IB over Temperature (2) Input Offset Current IOS VCM = 0V ±25 INPUT VOLTAGE RANGE Common-Mode Voltage Range Common-Mode Rejection Ratio VCM CMRR (V–) + 2 (V–) + 2V ≤ VCM ≤ (V+) – 2V 110 120 dB 20k || 8 Ω || pF INPUT IMPEDANCE Differential 9 Common-Mode (1) (2) 10 || 2 Ω || pF Full-power bandwidth = SR/(2π × VPP), where SR = slew rate. Specified by design and characterization. 3 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com ELECTRICAL CHARACTERISTICS: VS = ±2.25V to ±18V (continued) At TA = +25°C and RL = 2kΩ, unless otherwise noted. VCM = VOUT = midsupply, unless otherwise noted. Boldface limits apply over the specified temperature range, TA = –40°C to +85°C. OPA1611AI, OPA1612AI PARAMETER CONDITIONS MIN TYP MAX UNIT AOL (V–) + 0.2V ≤ VO ≤ (V+) – 0.2V, RL = 10kΩ 114 130 dB AOL (V–) + 0.6V ≤ VO ≤ (V+) – 0.6V, RL = 2kΩ 110 114 dB VOUT RL = 10kΩ, AOL ≥ 114dB (V–) + 0.2 (V+) – 0.2 RL = 2kΩ, AOL ≥ 110dB (V–) + 0.6 (V+) – 0.6 OPEN-LOOP GAIN Open-Loop Voltage Gain OUTPUT Voltage Output Output Current Open-Loop Output Impedance Short-Circuit Current V IOUT See Figure 27 mA ZO See Figure 28 Ω +55/–62 mA See Typical Characteristics pF ISC Capacitive Load Drive V CLOAD POWER SUPPLY Specified Voltage VS Quiescent Current (per channel) over Temperature IQ ±2.25 IOUT = 0A 3.6 (3) ±18 V 4.5 mA 5.5 mA TEMPERATURE RANGE Specified Range –40 +85 °C Operating Range –55 +125 °C Thermal Resistance θ JA SO-8 (3) 150 °C/W Specified by design and characterization. 4 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 TYPICAL CHARACTERISTICS At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. INPUT VOLTAGE NOISE DENSITY AND INPUT CURRENT NOISE DENSITY vs FREQUENCY 0.1Hz TO 10Hz NOISE 20nV/div Voltage Noise Density (nV/ÖHz) Current Noise Density (pA/ÖHz) 100 Voltage Noise Density 10 Current Noise Density 1 0.1 1 10 100 1k 10k Time (1s/div) 100k Frequency (Hz) Figure 1. Figure 2. MAXIMUM OUTPUT VOLTAGE vs FREQUENCY 30 10k Maximum output voltage range without slew-rate induced distortion VS = ±15V 25 EO 1k Output Voltage (VPP) Voltage Noise Spectral Density, EO (nV/?Hz) VOLTAGE NOISE vs SOURCE RESISTANCE Total Output Voltage Noise RS 100 Resistor Noise 10 20 15 VS = ±5V 10 VS = ±2.25V 5 2 2 2 EO = en + (in RS) + 4kTRS 1 100 1k 10k 100k 0 10k 1M 100k Figure 3. GAIN AND PHASE vs FREQUENCY 25 120 160 20 140 15 80 120 60 100 40 80 60 Phase 0 40 -20 20 -40 100 1k 10k 100k 1M 10M 0 100M G = +10 10 Gain (dB) Gain Phase (degrees) Gain (dB) CLOSED-LOOP GAIN vs FREQUENCY 180 20 10M Figure 4. 140 100 1M Frequency (Hz) Source Resistance, RS (W) G = -1 5 G = +1 0 -5 -10 -15 -20 -25 100k Frequency (Hz) 1M 10M 100M Frequency (Hz) Figure 5. Figure 6. 5 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. THD+N RATIO vs FREQUENCY G = +1 RL = 2kW G = -1 RL = 600W G = -1, RL = 2kW 0.00001 10 100 Total Harmonic Distortion + Noise (%) G = +1 RL = 600W 0.01 -140 RSOURCE OPA1611 -15V 0.001 RSOURCE = 0W 0.0001 RSOURCE = 150W Frequency (Hz) Figure 7. Figure 8. 100 -120 G = -1 RL = 2kW -140 100k 0.00001 100 1k 0.01 Total Harmonic Distortion + Noise (%) G = -1 RL = 600W G = +1 RL = 2kW 10k RSOURCE OPA1611 -15V 0.001 RL RSOURCE = 300W -120 0.0001 RSOURCE = 150W RSOURCE = 0W -140 100k 0.00001 10 100 1k 10k Frequency (Hz) Figure 10. THD+N RATIO vs OUTPUT AMPLITUDE INTERMODULATION DISTORTION vs OUTPUT AMPLITUDE 0.00001 0.000001 0.01 G = -1, RL = 2kW G = -1, RL = 600W G = +1, RL = 2kW G = +1, RL = 600W -140 -160 0.1 1 10 20 Intermodulation Distortion (%) -120 0.0001 0.01 -80 G = +1 SMPTE/DIN Two-Tone 4:1 (60Hz and 7kHz) 0.001 -100 DIM30 (3kHz square wave and 15kHz sine wave) 0.0001 -120 -140 0.00001 CCIF Twin-Tone (19kHz and 20kHz) Intermodulation Distortion (dB) -100 Total Harmonic Distortion + Noise (dB) 0.001 -80 -100 RSOURCE = 600W Figure 9. 1kHz Signal BW = 80kHz RSOURCE = 0W -80 VOUT = 3VRMS BW > 500kHz +15V Frequency (Hz) 0.01 20k Total Harmonic Distortion + Noise (dB) G = +1 RL = 600W 0.0001 10k THD+N RATIO vs FREQUENCY -100 VOUT = 3VRMS BW > 500kHz -120 -140 20 Total Harmonic Distortion + Noise (dB) Total Harmonic Distortion + Noise (%) RSOURCE = 300W 0.00001 THD+N RATIO vs FREQUENCY Total Harmonic Distortion + Noise (%) -100 RSOURCE = 600W 10k 20k 0.001 10 RL 1k Frequency (Hz) 1k -80 VOUT = 3VRMS BW = 80kHz +15V Total Harmonic Distortion + Noise (dB) VOUT = 3VRMS BW = 80kHz Total Harmonic Distortion + Noise (%) THD+N RATIO vs FREQUENCY -120 Total Harmonic Distortion + Noise (dB) 0.0001 -160 0.000001 0.1 Output Amplitude (VRMS) 1 10 20 Output Amplitude (VRMS) Figure 11. Figure 12. 6 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. CHANNEL SEPARATION vs FREQUENCY -100 160 VS = ±15V VOUT = 3.5VRMS G = +1 RL = 600W -110 -120 -130 -140 RL = 2kW -150 -160 RL = 5kW -170 Power-Supply Rejection Ratio (dB) Channel Separation (dB) -90 CMRR AND PSRR vs FREQUENCY (Referred to Input) Common-Mode Rejection Ratio (dB) -80 140 -PSRR 120 +PSRR 100 CMRR 80 60 40 20 -180 0 100 10 1k 10k 100k 1 10 100 1k Frequency (Hz) 10k 100k 1M Figure 13. Figure 14. SMALL-SIGNAL STEP RESPONSE (100mV) SMALL-SIGNAL STEP RESPONSE (100mV) 100M G = -1 CL = 50pF CF 20mV/div 20mV/div G = +1 CL = 50pF +15V OPA1611 -15V 10M Frequency (Hz) RI = 2kW RF = 5.6pF = 2kW +15V RL CL OPA1611 CL -15V Time (01.ms/div) Time (0.1ms/div) Figure 15. Figure 16. LARGE-SIGNAL STEP RESPONSE LARGE-SIGNAL STEP RESPONSE G = +1 CL = 50pF RL = 2kW G = -1 CL = 50pF RL = 2kW RF = 75W 2V/div 2V/div RF = 0W See Applications Information, Input Protection section Time (0.5ms/div) Time (0.5ms/div) Figure 17. Figure 18. 7 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. SMALL-SIGNAL OVERSHOOT vs CAPACITIVE LOAD (100mV Output Step) SMALL-SIGNAL OVERSHOOT vs CAPACITIVE LOAD (100mV Output Step) 25 50 CF = 5.6pF RS 40 20 RS = 25W RL -15V RS = 25W 30 CL 20 RS = 50W 10 0 RS OPA1611 CL -15V 10 RS = 50W G = -1 0 100 200 300 400 500 +15V 15 5 G = +1 0 RF = 2kW RI = 2kW OPA1611 Overshoot (%) Overshoot (%) RS = 0W +15V RS = 0W 0 600 100 200 300 400 500 600 700 800 900 1000 Capacitive Load (pF) Capacitive Load (pF) Figure 19. Figure 20. OPEN-LOOP GAIN vs TEMPERATURE IB AND IOS vs TEMPERATURE 120 1.0 0.8 100 IB and IOS Current (nA) 0.6 AOL (mV/V) 0.4 0.2 10kW 0 -0.2 -0.4 2kW -0.6 -IB 80 60 +IB 40 IOS 20 -0.8 -1.0 -40 0 10 -15 35 60 -40 85 -15 Figure 21. 70 50 85 QUIESCENT CURRENT vs TEMPERATURE 5.0 VS = ±18V +IB 4.5 60 50 4.0 40 30 IQ (mA) IB and IOS (nA) 35 Figure 22. IB AND IOS vs COMMON-MODE VOLTAGE 80 10 Temperature (°C) Temperature (°C) IOS 20 3.5 3.0 10 -IB 0 2.5 Common-Mode Range -10 2.0 -20 -18 -12 -6 0 6 12 18 -40 -15 Common-Mode Voltage (V) Figure 23. 10 35 60 85 Temperature (°C) Figure 24. 8 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. QUIESCENT CURRENT vs SUPPLY VOLTAGE SHORT-CIRCUIT CURRENT vs TEMPERATURE 4.0 75 3.9 70 3.8 65 60 3.6 ISC (mA) IQ (mA) 3.7 -ISC 3.5 3.4 55 +ISC 50 45 3.3 40 3,2 35 Specified Supply-Voltage Range 3.1 3.0 30 0 4 8 12 16 20 24 28 32 36 -50 -25 0 25 50 75 100 Figure 25. Figure 26. OUTPUT VOLTAGE vs OUTPUT CURRENT OPEN-LOOP OUTPUT IMPEDANCE vs FREQUENCY 15 10k 14 1k 13 VS = ±15V Dual version with both channels driven simultaneously -13 125 Temperature (°C) +25°C ZO (W) Output Voltage (V) Supply Voltage (V) +85°C -40°C 100 10 1 -14 0.1 -15 0 10 20 30 40 50 10 100 Output Current (mA) 1k 10k 100k 1M 10M 100M Frequency (Hz) Figure 27. Figure 28. 9 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com APPLICATION INFORMATION The OPA1611 and OPA1612 are unity-gain stable, precision op amps with very low noise; these devices are also free from output phase reversal. Applications with noisy or high-impedance power supplies require decoupling capacitors close to the device power-supply pins. In most cases, 0.1μF capacitors are adequate. Figure 29 shows a simplified internal schematic of the OPA1611. OPERATING VOLTAGE The OPA161x series op amps operate from ±2.25V to ±18V supplies while maintaining excellent performance. The OPA161x series can operate with as little as +4.5V between the supplies and with up to +36V between the supplies. However, some applications do not require equal positive and negative output voltage swing. With the OPA161x series, power-supply voltages do not need to be equal. For example, the positive supply could be set to +25V with the negative supply at –5V. In all cases, the common-mode voltage must be maintained within the specified range. In addition, key parameters are assured over the specified temperature range of TA = –40°C to +85°C. Parameters that vary with operating voltage or temperature are shown in the Typical Characteristics. V+ Pre-Output Driver IN- OUT IN+ V- Figure 29. OPA1611 Simplified Schematic 10 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 The input terminals of the OPA1611 and the OPA1612 are protected from excessive differential voltage with back-to-back diodes, as Figure 30 illustrates. In most circuit applications, the input protection circuitry has no consequence. However, in low-gain or G = +1 circuits, fast ramping input signals can forward bias these diodes because the output of the amplifier cannot respond rapidly enough to the input ramp. This effect is illustrated in Figure 17 of the Typical Characteristics. If the input signal is fast enough to create this forward bias condition, the input signal current must be limited to 10mA or less. If the input signal current is not inherently limited, an input series resistor (RI) and/or a feedback resistor (RF) can be used to limit the signal input current. This input series resistor degrades the low-noise performance of the OPA1611 and is examined in the following Noise Performance section. Figure 30 shows an example configuration when both current-limiting input and feedback resistors are used. RF - OPA1611 RI Input Output current noise is negligible, and voltage noise generally dominates. The low voltage noise of the OPA161x series op amps makes them a good choice for use in applications where the source impedance is less than 1kΩ. The equation in Figure 31 shows the calculation of the total circuit noise, with these parameters: • en = Voltage noise • In = Current noise • RS = Source impedance • k = Boltzmann’s constant = 1.38 × 10–23 J/K • T = Temperature in degrees Kelvin (K) VOLTAGE NOISE SPECTRAL DENSITY vs SOURCE RESISTANCE Voltage Noise Spectral Density, EO (nV/?Hz) INPUT PROTECTION 10k EO 1k Total Output Voltage Noise RS 100 Resistor Noise 10 2 2 2 EO = en + (in RS) + 4kTRS 1 100 + 1k 10k 100k 1M Source Resistance, RS (W) Figure 31. Noise Performance of the OPA1611 in Unity-Gain Buffer Configuration Figure 30. Pulsed Operation BASIC NOISE CALCULATIONS NOISE PERFORMANCE Figure 31 shows the total circuit 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 OPA1611 (GBW = 40MHz, G = +1) is shown with total circuit noise calculated. The op amp itself contributes both a voltage noise component and a current 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. Therefore, the lowest noise op amp for a given application depends on the source impedance. For low source impedance, 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. Figure 31 plots this function. The source impedance is usually fixed; consequently, select the op amp and the feedback resistors to minimize the respective contributions to the total noise. 11 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com Figure 32 illustrates 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. Noise in Noninverting Gain Configuration Noise at the output: R2 2 2 R1 EO = 1 + R2 R1 2 2 2 2 2 2 en + e1 + e2 + (inR2) + eS + (inRS) EO R2 Where eS = Ö4kTRS ´ 1 + R1 2 1+ R2 R1 = thermal noise of RS RS R2 e1 = Ö4kTR1 ´ R1 VS = thermal noise of R1 e2 = Ö4kTR2 = thermal noise of R2 Noise in Inverting Gain Configuration Noise at the output: R2 2 2 EO R1 RS = 1+ R2 R1 + RS 2 EO Where eS = Ö4kTRS ´ 2 2 2 2 en + e1 + e2 + (inR2) + eS R2 R1 + RS = thermal noise of RS VS e1 = Ö4kTR1 ´ R2 R1 + RS = thermal noise of R1 e2 = Ö4kTR2 = thermal noise of R2 For the OPA161x series op amps at 1kHz, en = 1.1nV/√Hz and in = 1.7pA/√Hz. Figure 32. Noise Calculation in Gain Configurations 12 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 TOTAL HARMONIC DISTORTION MEASUREMENTS Validity of this technique can be verified by duplicating measurements at high gain and/or high frequency where the distortion is within the measurement capability of the test equipment. Measurements for this data sheet were made with an Audio Precision System Two distortion/noise analyzer, which greatly simplifies such repetitive measurements. The measurement technique can, however, be performed with manual distortion measurement instruments. The OPA161x series op amps have excellent distortion characteristics. THD + Noise is below 0.00008% (G = +1, VO = 3VRMS, BW = 80kHz) throughout the audio frequency range, 20Hz to 20kHz, with a 2kΩ load (see Figure 7 for characteristic performance). The distortion produced by OPA1611 series op amps is below the measurement limit of many commercially available distortion analyzers. However, a special test circuit (such as Figure 33 shows) can be used to extend the measurement capabilities. CAPACITIVE LOADS The dynamic characteristics of the OPA1611 and OPA1612 have been optimized for commonly encountered gains, loads, and operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the phase margin of the amplifier and can lead to gain peaking or oscillations. As a result, heavier capacitive loads must be isolated from the output. The simplest way to achieve this isolation is to add a small resistor (RS equal to 50Ω, for example) in series with the output. Op amp distortion can be considered an internal error source that can be referred to the input. Figure 33 shows a circuit that causes the op amp distortion to be 101 times (or approximately 40dB) greater than that normally produced by the op amp. The addition of R3 to the otherwise standard noninverting amplifier configuration alters the feedback factor or noise gain of the circuit. The closed-loop gain is unchanged, but the feedback available for error correction is reduced by a factor of 101, thus extending the resolution by 101. Note that the input signal and load applied to the op amp are the same as with conventional feedback without R3. The value of R3 should be kept small to minimize its effect on the distortion measurements. R1 This small series resistor also prevents excess power dissipation if the output of the device becomes shorted. Figure 19 and Figure 20 illustrate graphs of Small-Signal Overshoot vs Capacitive Load for several values of RS. Also, refer to Applications Bulletin AB-028 (literature number SBOA015, available for download from the TI web site) for details of analysis techniques and application circuits. R2 SIG. DIST. GAIN GAIN R3 Signal Gain = 1+ VO = 3VRMS OPA1611 R2 R1 Distortion Gain = 1+ R2 R1 II R3 Generator Output R1 R2 R3 1 101 ¥ 1kW 10W -1 101 5kW 5kW 50W Analyzer Input Audio Precision System Two(1) with PC Controller Load (1) For measurement bandwidth, see Figure 7 through Figure 12. Figure 33. Distortion Test Circuit 13 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com POWER DISSIPATION OPA1611 and OPA1612 series op amps are capable of driving 2kΩ loads with a power-supply voltage up to ±18V. Internal power dissipation increases when operating at high supply voltages. Copper leadframe construction used in the OPA1611 and OPA1612 series op amps improves heat dissipation compared to conventional materials. Circuit board layout can also help minimize junction temperature rise. Wide copper traces help dissipate the heat by acting as an additional heat sink. Temperature rise can be further minimized by soldering the devices to the circuit board rather than using a socket. ELECTRICAL OVERSTRESS Designers often ask questions about the capability of an operational amplifier to withstand electrical overstress. These questions tend to focus on the device inputs, but may involve the supply voltage pins or even the output pin. Each of these different pin functions have electrical stress limits determined by the voltage breakdown characteristics of the particular semiconductor fabrication process and specific circuits connected to the pin. Additionally, internal electrostatic discharge (ESD) protection is built into these circuits to protect them from accidental ESD events both before and during product assembly. circuits contained in the OPA161x series (indicated by the dashed line area). The ESD protection circuitry involves several current-steering diodes connected from the input and output pins and routed back to the internal power-supply lines, where they meet at an absorption device internal to the operational amplifier. This protection circuitry is intended to remain inactive during normal circuit operation. An ESD event produces a short duration, high-voltage pulse that is transformed into a short duration, high-current pulse as it discharges through a semiconductor device. The ESD protection circuits are designed to provide a current path around the operational amplifier core to prevent it from being damaged. The energy absorbed by the protection circuitry is then dissipated as heat. When an ESD voltage develops across two or more of the amplifier device pins, current flows through one or more of the steering diodes. Depending on the path that the current takes, the absorption device may activate. The absorption device has a trigger, or threshold voltage, that is above the normal operating voltage of the OPA161x but below the device breakdown voltage level. Once this threshold is exceeded, the absorption device quickly activates and clamps the voltage across the supply rails to a safe level. It is helpful to have a good understanding of this basic ESD circuitry and its relevance to an electrical overstress event. Figure 34 illustrates the ESD 14 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 www.ti.com........................................................................................................................................................ SBOS450A – JULY 2009 – REVISED AUGUST 2009 When the operational amplifier connects into a circuit such as the one Figure 34 shows, the ESD protection components are intended to remain inactive and not become involved in the application circuit operation. However, circumstances may arise where an applied voltage exceeds the operating voltage range of a given pin. Should this condition occur, there is a risk that some of the internal ESD protection circuits may be biased on, and conduct current. Any such current flow occurs through steering diode paths and rarely involves the absorption device. direct current path is established between the +VS and –VS supplies. The power dissipation of the absorption device is quickly exceeded, and the extreme internal heating destroys the operational amplifier. Another common question involves what happens to the amplifier if an input signal is applied to the input while the power supplies +VS and/or –VS are at 0V. Again, it depends on the supply characteristic while at 0V, or at a level below the input signal amplitude. If the supplies appear as high impedance, then the operational amplifier supply current may be supplied by the input source via the current steering diodes. This state is not a normal bias condition; the amplifier most likely will not operate normally. If the supplies are low impedance, then the current through the steering diodes can become quite high. The current level depends on the ability of the input source to deliver current, and any resistance in the input path. Figure 34 depicts a specific example where the input voltage, VIN, exceeds the positive supply voltage (+VS) by 500mV or more. Much of what happens in the circuit depends on the supply characteristics. If +VS can sink the current, one of the upper input steering diodes conducts and directs current to +VS. Excessively high current levels can flow with increasingly higher VIN. As a result, the datasheet specifications recommend that applications limit the input current to 10mA. If there is an uncertainty about the ability of the supply to absorb this current, external zener diodes may be added to the supply pins as shown in Figure 34. The zener voltage must be selected such that the diode does not turn on during normal operation. However, its zener voltage should be low enough so that the zener diode conducts if the supply pin begins to rise above the safe operating supply voltage level. If the supply is not capable of sinking the current, VIN may begin sourcing current to the operational amplifier, and then take over as the source of positive supply voltage. The danger in this case is that the voltage can rise to levels that exceed the operational amplifier absolute maximum ratings. In extreme but rare cases, the absorption device triggers on while +VS and –VS are applied. If this event happens, a RF +V +VS OPA1611 RI ESD CurrentSteering Diodes -In +In Op-Amp Core Edge-Triggered ESD Absorption Circuit ID VIN Out RL (1) -V -VS (1) VIN = +VS + 500mV. Figure 34. Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application 15 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 OPA1611 OPA1612 SBOS450A – JULY 2009 – REVISED AUGUST 2009........................................................................................................................................................ www.ti.com APPLICATION CIRCUIT 820W 2200pF +VA (+15V) 0.1mF 330W IOUTL+ OPA1611 2700pF -VA (-15V) 680W 620W Audio DAC with Differential Current Outputs 0.1mF +VA (+15V) 0.1mF 100W 820W OPA1611 8200pF 2200pF +VA (+15V) L Ch Output -VA (-15V) 0.1mF 0.1mF 680W 620W IOUTLOPA1611 330W 2700pF -VA (-15V) 0.1mF Figure 35. Audio DAC Post Filter (I/V Converter and Low-Pass Filter) 16 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1611 OPA1612 PACKAGE OPTION ADDENDUM www.ti.com 18-Aug-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty OPA1611AID ACTIVE SOIC D 8 OPA1611AIDR ACTIVE SOIC D 8 OPA1612AID ACTIVE SOIC D 8 OPA1612AIDR ACTIVE SOIC D 8 75 Lead/Ball Finish MSL Peak Temp (3) Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR 75 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. 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Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 15-Aug-2009 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant OPA1611AIDR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 OPA1612AIDR SOIC D 8 2500 330.0 12.4 6.4 5.2 2.1 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 15-Aug-2009 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) OPA1611AIDR SOIC D 8 2500 346.0 346.0 29.0 OPA1612AIDR SOIC D 8 2500 346.0 346.0 29.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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