OP A1 641 OP A1 OPA1641 OPA1642 OPA1644 642 OP A1 64 4 Burr-Brown Audio www.ti.com SBOS484 – DECEMBER 2009 ™ High-Performance, JFET-Input AUDIO OPERATIONAL AMPLIFIERS Check for Samples: OPA1641 OPA1642 OPA1644 FEATURES DESCRIPTION • SUPERIOR SOUND QUALITY • TRUE JFET INPUT OP AMP WITH LOW INPUT BIAS CURRENT • LOW NOISE: 5.1nV/√Hz at 1kHz • ULTRALOW DISTORTION: 0.00005% at 1kHz • HIGH SLEW RATE: 20V/μs • UNITY GAIN STABLE • NO PHASE REVERSAL • LOW QUIESCENT CURRENT: 1.8mA per Channel • RAIL-TO-RAIL OUTPUT • WIDE SUPPLY RANGE: ±2.25V to ±18V • SINGLE, DUAL, AND QUAD VERSIONS AVAILABLE The OPA1641 (single), OPA1642 (dual), and OPA1644 (quad) series are JFET-input, ultralow distortion, low-noise operational amplifiers fully specified for audio applications. 1 234 The OPA1641, OPA1642, and OPA1644 rail-to-rail output swing allows increased headroom, making these devices ideal for use in any audio circuit. Features include 5.1nV/√Hz noise, low THD+N (0.00005%), a low input bias current of 2pA, and low quiescent current of 1.8mA per channel. These devices operate over a very wide supply voltage range of ±2.25V to ±18V. The OPA1641, OPA1642, and OPA1644 series of op amps are unity-gain stable and provide excellent dynamic behavior over a wide range of load conditions. The dual and quad versions feature completely independent circuitry for lowest crosstalk and freedom from interactions between channels, even when overdriven or overloaded. APPLICATIONS • • • • • PROFESSIONAL AUDIO EQUIPMENT ANALOG AND DIGITAL MIXING CONSOLES BROADCAST STUDIO EQUIPMENT HIGH-END A/V RECEIVERS HIGH-END BLU-RAY™ PLAYERS The OPA1641, OPA1642, and OPA1644 specified from –40°C to +85°C. SoundPlus™ are V+ Pre-Output Driver IN- OUT IN+ V1 2 3 4 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. BLU-RAY is a trademark of Blu-Ray Disc Assocation. All other trademarks are the property of their respective owners. UNLESS OTHERWISE NOTED this document contains PRODUCTION DATA information current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2009, Texas Instruments Incorporated OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 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). VALUE UNIT 40 V Supply Voltage, VS = (V+) – (V–) Input Voltage (2) (V–) –0.5 to (V+) +0.5 V ±10 mA ±VS V Input Current (2) Differential Input Voltage Output Short-Circuit (3) Continuous Operating Temperature, TA –55 to +125 °C Storage Temperature, TA –65 to +150 °C Junction Temperature, TJ +150 °C Human Body Model (HBM) 3000 V Charged Device Model (CDM) 1000 V Machine Model (MM) 100 V ESD Ratings (1) (2) (3) 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. Input terminals are diode-clamped to the power-supply rails. Input signals that can swing more than 0.5V beyond the supply rails should be current-limited to 10mA or less. Short-circuit to VS/2 (ground in symmetrical dual-supply setups), one amplifier per package. PACKAGE/ORDERING INFORMATION (1) PRODUCT OPA1641 OPA1642 OPA1644 (1) (2) 2 (2) PACKAGE-LEAD PACKAGE DESIGNATOR PACKAGE MARKING SO-8 D O1641A MSOP-8 DGK 1641 SO-8 D O1642A MSOP-8 DGK 1642 SO-14 D O1644AG4 TSSOP-14 PW O1644A 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. Shaded cells indicate product-preview device. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 ELECTRICAL CHARACTERISTICS: VS = +4.5V to +36; ±2.25V to ±18V At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. OPA1641, OPA1642, OPA1644 (1) PARAMETER CONDITIONS MIN TYP MAX UNIT AUDIO PERFORMANCE Total Harmonic Distortion + Noise THD+N Intermodulation Distortion G = +1, f = 1kHz, VO = 3VRMS IMD 0.00005 % –126 dB G = +1, VO = 3VRMS SMPTE/DIN Two-Tone, 4:1 (60Hz and 7kHz) DIM 30 (3kHz square wave and 15kHz sine wave) CCIF Twin-Tone (19kHz and 20kHz) 0.00004 % –128 dB 0.00008 % –122 dB 0.00007 % –123 dB MHz FREQUENCY RESPONSE Gain-Bandwidth Product Slew Rate GBW G = +1 11 SR G = +1 20 V/μs VO = 1VP 3.2 MHz Full-Power Bandwidth (2) Overload Recovery Time (3) G = –10 600 ns Channel Separation (Dual and Quad) f = 1kHz –126 dB f = 20Hz to 20kHz 4.3 μVPP f = 10Hz 8 nV/√Hz f = 100Hz 5.8 nV/√Hz f = 1kHz 5.1 nV/√Hz f = 1kHz 0.8 fA/√Hz NOISE Input Voltage Noise Input Voltage Noise Density Input Current Noise Density en In OFFSET VOLTAGE Input Offset Voltage vs Power Supply VOS VS = ±18V 1 3.5 mV VS = ±2.25V to ±18V 0.14 2 μV/V IB VCM = 0V ±2 ±20 pA IOS VCM = 0V ±2 ±20 pA PSRR INPUT BIAS CURRENT Input Bias Current Input Offset Current INPUT VOLTAGE RANGE Common-Mode Voltage Range VCM Common-Mode Rejection Ratio CMRR (V–)-0.1 VCM = (V–) – 0.1V to (V+) – 3.5V, VS = ±18V 120 (V+)–3.5 V 126 dB 1013 || 8 Ω || pF INPUT IMPEDANCE Differential 13 VCM = (V–) – 0.1V to (V+) – 3.5V Common-Mode 10 || 6 Ω || pF OPEN-LOOP GAIN Open-Loop Voltage Gain (1) (2) (3) AOL (V–) + 0.2V ≤ VO ≤ (V+) – 0.2V, RL = 10kΩ 120 134 dB (V–) + 0.35V ≤ VO ≤ (V+) – 0.35V, RL = 2kΩ 114 126 dB OPA1644 device status is product-preview. Full power bandwidth = SR/(2π × VP), where SR = slew rate. See Figure 21 and Figure 22. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 3 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com ELECTRICAL CHARACTERISTICS: VS = +4.5V to +36; ±2.25V to ±18V (continued) At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. OPA1641, OPA1642, OPA1644 (1) PARAMETER CONDITIONS MIN TYP MAX UNIT OUTPUT Voltage Output Swing from Rail VO Output Current RL = 10kΩ, AOL ≥ 120dB (V–)+0.2 (V+)–0.2 V RL = 2kΩ, AOL ≥ 114dB (V–)+0.35 (V+)–0.35 V IOUT See Typical Characteristics Open-Loop Output Impedance ZO Short-Circuit Current ISC Source ISC Sink Capacitive Load Drive CLOAD See Typical Characteristics Ω +36 mA –30 mA See Typical Characteristics POWER SUPPLY Specified Voltage VS Quiescent Current (per amplifier) IQ ±2.25 IOUT = 0A 1.8 ±18 V 2.3 mA TEMPERATURE RANGE Specified Range –40 +85 °C Operating Range –55 +125 °C θJA Thermal Resistance SO-8 138 °C/W MSOP-8 180 °C/W SO-14 97 °C/W TSSOP-14 135 °C/W PIN ASSIGNMENTS OPA1641 SO-8, MSOP-8 (TOP VIEW) NC (1) OPA1644 SO-14, TSSOP-14 (TOP VIEW) (1) 1 8 NC -In 2 7 V+ +In 3 6 Out V- 4 5 NC Out A 1 -In A 2 A (1) NC denotes no internal connection. OPA1642 SO-8, MSOP-8 (TOP VIEW) 4 1 -In A 2 +In A 3 V- 4 A B Out D 13 -In D D +In A 3 12 +In D V+ 4 11 V- + In B 5 10 + In C (1) B OUT A 14 Note: 8 V+ 7 Out B 6 -In B 5 +In B C -In B 6 9 -In C Out B 7 8 Out C Product-preview device. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 TYPICAL CHARACTERISTICS: VS = ±18V At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. INPUT VOLTAGE NOISE DENSITY vs FREQUENCY 0.1Hz to 10Hz NOISE 100nV/div Voltage Noise Density (nV/ÖHz) 100 10 1 0.1 1 10 100 1k 10k Time (1s/div) 100k Frequency (Hz) Figure 1. Figure 2. MAXIMUM OUTPUT VOLTAGE vs FREQUENCY CMRR AND PSRR vs FREQUENCY (Referred to Input) 160 35 25 Common-Mode Rejection Ratio (dB) Power-Supply Rejection Ratio (dB) 30 Output Voltage (VPP) Maximum output voltage range without slew-rate induced distortion VS = ±15V 20 15 VS = ±5V 10 VS = ±2.25V 5 140 CMRR 120 100 -PSRR 80 +PSRR 60 40 20 0 0 10k 100k 1M 1 10M 10 100 1k 10k 100k 1M 10M 100M Frequency (Hz) Frequency (Hz) Figure 3. Figure 4. GAIN AND PHASE vs FREQUENCY 140 CLOSED-LOOP GAIN vs FREQUENCY 180 30 120 Gain 20 135 90 60 40 Phase G = +10 Gain (dB) 80 Phase (degrees) Gain (dB) 100 10 G = +1 0 45 20 -10 G = -1 0 -20 50 100 1k 10k 100k 1M 10M 0 100M -20 100k Frequency (Hz) 1M 10M 100M Frequency (Hz) Figure 5. Figure 6. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 5 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com TYPICAL CHARACTERISTICS: VS = ±18V (continued) At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. THD+N RATIO vs FREQUENCY G = -1 RL = 2kW G = +1 RL = 600W G = -1 RL = 600W 0.0001 -120 G = +1 RL = 2kW 0.00001 Total Harmonic Distortion + Noise (%) VOUT = 3VRMS BW = 80kHz -140 10 100 -80 0.01 RSOURCE OPA1641 -15V 0.001 -120 0.0001 RSOURCE = 0W 0.00001 10 Frequency (Hz) Figure 7. Figure 8. 10k 20k 100 -120 G = +1 RL = 2kW -140 100k 0.00001 10k RSOURCE = 600W -15V 0.001 RL RSOURCE = 300W RSOURCE = 150W 0.0001 VOUT = 3VRMS BW > 500kHz 0.00001 100 1k -140 100k 10k Frequency (Hz) THD+N RATIO vs OUTPUT AMPLITUDE INTERMODULATION DISTORTION vs OUTPUT AMPLITUDE -80 0.0001 -120 G = -1, RL = 2kW G = +1, RL = 2kW -140 1 10 20 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 CCIF Twin-Tone (19kHz and 20kHz) 0.00001 Intermodulation Distortion (dB) -100 -120 RSOURCE = 0W Figure 10. Output Amplitude (VRMS) -140 0.1 1 10 20 Output Amplitude (VRMS) Figure 11. 6 -100 Figure 9. 0.001 0.1 RSOURCE OPA1641 Frequency (Hz) BW = 80kHz 1kHz Signal RSOURCE = 0W 0.00001 -80 +15V 10 Total Harmonic Distortion + Noise (dB) Total Harmonic Distortion + Noise (%) 1k Total Harmonic Distortion + Noise (%) G = -1 RL = 2kW Intermodulation Distortion (%) Total Harmonic Distortion + Noise (%) -100 0.0001 100 -140 20k Total Harmonic Distortion + Noise (dB) G = +1 RL = 600W 10k 0.01 Total Harmonic Distortion + Noise (dB) G = -1 RL = 600W 0.001 VOUT = 3VRMS BW = 80kHz THD+N RATIO vs FREQUENCY -80 VOUT = 3VRMS BW > 500kHz -100 RSOURCE = 600W THD+N RATIO vs FREQUENCY 0.01 RSOURCE = 300W RL 1k Frequency (Hz) 1k 0.01 10 RSOURCE = 150W +15V Total Harmonic Distortion + Noise (dB) Total Harmonic Distortion + Noise (%) THD+N RATIO vs FREQUENCY -100 Total Harmonic Distortion + Noise (dB) 0.001 Figure 12. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 TYPICAL CHARACTERISTICS: VS = ±18V (continued) At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. CHANNEL SEPARATION vs FREQUENCY -90 NO PHASE REVERSAL VS = ±15V VOUT = 3VRMS G = +1 Output -100 RL = 600W 5V/div Channel Separation (dB) -80 -110 -120 +18V RL = 2kW OPA1641 Output -18V 37VPP Sine Wave (±18.5V) -130 RL = 5kW -140 100 10 1k 10k Time (0.4ms/div) 100k Frequency (Hz) Figure 13. Figure 14. SMALL-SIGNAL STEP RESPONSE (100mV) SMALL-SIGNAL STEP RESPONSE (100mV) G = -1 CL = 100pF 20mV/div 20mV/div G = +1 CL = 100pF +15V OPA1641 -15V RL RI = 2kW RF = 2kW +15V OPA1641 CL CL -15V Time (100ns/div) Time (100ns/div) Figure 15. Figure 16. LARGE-SIGNAL STEP RESPONSE LARGE-SIGNAL STEP RESPONSE G = +1 CL = 100pF 2V/div 2V/div G = -1 CL = 100pF Time (400ns/div) Time (400ns/div) Figure 17. Figure 18. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 7 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com TYPICAL CHARACTERISTICS: VS = ±18V (continued) At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. POSITIVE OVERLOAD RECOVERY NEGATIVE OVERLOAD RECOVERY VOUT G = -10 G = -10 5V/div 5V/div VIN 20kW 20kW 2kW VIN 2kW VOUT OPA1641 OPA1641 VIN VOUT VIN VOUT Time (0.4ms/div) Time (0.4ms/div) Figure 19. Figure 20. SMALL-SIGNAL OVERSHOOT vs CAPACITIVE LOAD (100mV Output Step) SMALL-SIGNAL OVERSHOOT vs CAPACITIVE LOAD (100mV Output Step) 40 G = +1 35 45 ROUT = 0W RI = 2kW +15V 40 ROUT ROUT = 0W RF = 2kW +15V OPA1641 RL -15V ROUT = 24W 15 ROUT = 51W 30 ROUT = 24W -15V 25 20 ROUT = 51W 15 10 10 5 5 0 0 0 OPA1641 CL 25 20 ROUT 35 CL Overshoot (%) Overshoot (%) 30 G = -1 100 200 300 400 500 600 700 800 900 1000 0 100 200 300 400 500 600 700 800 900 1000 Capacitive Load (pF) Capacitive Load (pF) Figure 21. Figure 22. OPEN-LOOP GAIN vs TEMPERATURE IB AND IOS vs TEMPERATURE 80 0 70 -0.2 60 10kW IB and IOS (pA) AOL (mV/V) -0.4 -0.6 2kW -0.8 +IB 50 40 30 20 -IB 10 0 -1.0 -10 -1.2 -40 -IOS -20 -15 10 35 60 85 -40 10 -15 Figure 23. 8 35 60 85 Temperature (°C) Temperature (°C) Figure 24. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 TYPICAL CHARACTERISTICS: VS = ±18V (continued) At TA = +25°C, RL = 2kΩ connected to midsupply, VCM = VOUT = midsupply, unless otherwise noted. IB AND IOS vs COMMON-MODE VOLTAGE 10 8 QUIESCENT CURRENT vs TEMPERATURE 2.5 VS = ±18V 2.0 +IB 4 -IB 2 0 IQ (mA) IB and IOS (pA) 6 IOS -2 1.5 1.0 -4 -6 0.5 -8 Common-Mode Range -10 -18 -12 0 -6 6 12 0 -40 -25 -10 18 5 20 Common-Mode Voltage (V) Figure 25. 50 65 80 95 110 125 Figure 26. QUIESCENT CURRENT vs SUPPLY VOLTAGE SHORT-CIRCUIT CURRENT vs TEMPERATURE 2.00 60 1.75 50 1.50 ISC-SOURCE 40 ISC (mA) 1.25 IQ (mA) 35 Temperature (°C) 1.00 0.75 30 ISC-SINK 20 0.50 0.25 10 Specified Supply-Voltage Range 0 VOUT = Midsupply (includes self-heating) 0 0 4 8 12 16 20 24 28 32 36 -50 -25 0 25 50 75 100 125 Temperature (°C) Supply Voltage (V) Figure 27. Figure 28. OUTPUT VOLTAGE vs OUTPUT CURRENT OPEN-LOOP OUTPUT IMPEDANCE vs FREQUENCY 1k 18.0 17.5 16.5 100 16.0 -40°C +25°C +85°C ZO (W) Output Voltage (V) 17.0 +125°C -16.0 10 -16.5 -17.0 -17.5 1 -18.0 0 10 20 30 40 50 10 100 1k Output Current (mA) Figure 29. 10k 100k 1M 10M 100M Frequency (Hz) Figure 30. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 9 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com APPLICATION INFORMATION The OPA1641, OPA1642, and OPA1644 are unity-gain stable, audio operational amplifiers with very low noise, input bias current, and input offset voltage. Applications with noisy or high-impedance power supplies require decoupling capacitors placed close to the device pins. In most cases, 0.1μF capacitors are adequate. The front-page drawing shows a simplified schematic of the OPA1641. 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) OPERATING VOLTAGE For more details on calculating noise, see the next section on Basic Noise Calculations. 10k Votlage Noise Spectral Density, EO The OPA1641, OPA1642, and OPA1644 series of op amps can be used with single or dual supplies from an operating range of VS = +4.5V (±2.25V) and up to VS = +36V (±18V). These devices do not require symmetrical supplies; it only requires a minimum supply voltage of +4.5V (±2.25V). For VS less than ±3.5V, the common-mode input range does not include midsupply. Supply voltages higher than +40V can permanently damage the device; see Absolute Maximum Ratings table. Key parameters are specified over the operating temperature range, TA = –40°C to +85°C. Key parameters that vary over the supply voltage or temperature range are shown in the Typical Characteristics section of this data sheet. EO 1k 100 OPA1641 Resistor Noise 10 2 2 2 EO = en + (in RS) + 4kTRS 1 100 1k 10k 100k 1M Source Resistance, RS (W) NOISE PERFORMANCE Figure 31 shows the total circuit noise for varying source impedances with the operational amplifier in a unity-gain configuration (with no feedback resistor network and therefore no additional noise contributions). The OPA1641, OPA1642, and OPA1644 are 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, current noise is negligible, and voltage noise generally dominates. The OPA1641, OPA1642, and OPA1644 family has both low voltage noise and extremely low current noise because of the FET input of the op amp. As a result, the current noise contribution of the OPA164x series is negligible for any practical source impedance, which makes it the better choice for applications with high source impedance. 10 OPA1611 RS Figure 31. Noise Performance of the OPA1611 and OPA1641 in Unity-Gain Buffer Configuration BASIC NOISE CALCULATIONS Low-noise circuit design requires careful analysis of all noise sources. External noise sources can dominate in many cases; consider the effect of source resistance on overall op amp noise performance. 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 plotted in Figure 31. The source impedance is usually fixed; consequently, select the op amp and the feedback resistors to minimize the respective contributions to the total noise. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 Figure 32 illustrates both noninverting (A) and inverting (B) op amp circuit configurations with gain. In circuit configurations with gain, the feedback network resistors also contribute noise. In general, the current noise of the op amp reacts with the feedback resistors to create additional noise components. However, the extremely low current noise of the OPA164x means that its current noise contribution can be neglected. A) Noise in Noninverting Gain Configuration The feedback resistor values can generally be chosen to make these noise sources negligible. Note that low impedance feedback resistors will load the output of the amplifier. The equations for total noise are shown for both configurations. space space Noise at the output: R2 2 R2 EO2 = 1 + R1 R1 2 en2 + R2 R1 2 e12 + e22 + 1 + R2 R1 es2 EO RS Where eS = 4kTRS = thermal noise of RS e1 = 4kTR1 = thermal noise of R1 e2 = 4kTR2 = thermal noise of R2 VS B) Noise in Inverting Gain Configuration Noise at the output: R2 2 2 EO R1 RS = 1+ R2 R1 + RS e n2 + 2 R2 R 1 + RS e12 + e22 + 2 R2 R 1 + RS e s2 EO VS Where eS = 4kTRS = thermal noise of RS e1 = 4kTR1 = thermal noise of R1 e2 = 4kTR2 = thermal noise of R2 For the OPA164x series op amps at 1kHz, en = 5.1nV/ÖHz Figure 32. Noise Calculation in Gain Configurations Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 11 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com TOTAL HARMONIC DISTORTION MEASUREMENTS The OPA164x series op amps have excellent distortion characteristics. THD + Noise is below 0.00005% (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 the OPA164x 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. 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 R1 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. 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. space R2 SIGNAL DISTORTION GAIN GAIN R3 Signal Gain = 1+ OPA1641 VO = 3VRMS R2 R1 Distortion Gain = 1+ R2 R1 II R3 Generator Output R1 R2 R3 1 101 ¥ 1kW 10W 11 101 100W 1kW 11W Analyzer Input Audio Precision System Two(1) with PC Controller (1) Load For measurement bandwidth, see Figure 7 through Figure 12. Figure 33. Distortion Test Circuit 12 Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 SOURCE IMPEDANCE AND DISTORTION PHASE-REVERSAL PROTECTION For lowest distortion with a source or feedback network, the impedance seen by the positive and negative inputs in noninverting applications should be matched. The n-channel JFETs in the FET input stage exhibit a varying input capacitance with applied common-mode input voltage. In inverting configurations, the input does not vary with input voltage because the inverting input is held at virtual ground. However, in noninverting applications, the inputs do vary, and the gate-to-source voltage is not constant. This effect produces increased distortion as a result of the varying capacitance for unmatched source impedances. The OPA1641, OPA1642, and OPA1644 family has internal phase-reversal protection. Many FET- and bipolar-input op amps exhibit a phase reversal when the input is driven beyond its linear common-mode range. This condition is most often encountered in noninverting circuits when the input is driven beyond the specified common-mode voltage range, causing the output to reverse into the opposite rail. The input circuitry of the OPA1641, OPA1642, and OPA1644 prevents phase reversal with excessive common-mode voltage; instead, the output limits into the appropriate rail (see Figure 14). To maintain low distortion, match unbalanced source impedance with appropriate values in the feedback network as shown in Figure 34. Of course, the unbalanced impedance may be from gain-setting resistors in the feedback path. If the parallel combination of R1 and R2 is greater than 2kΩ, a matching impedance on the noninverting input should be used. As always, resistor values should be minimized to reduce the effects of thermal noise. R1 R2 VOUT OPA164x VIN If RS > 2kW or R1 || R2 > 2kW RS = R1 || R2 Figure 34. Impedance Matching for Maintaining Low Distortion in Noninverting Circuits CAPACITIVE LOAD AND STABILITY The dynamic characteristics of the OPA164x 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 (ROUT equal to 50Ω, for example) in series with the output. Figure 21 and Figure 22 illustrate graphs of Small-Signal Overshoot vs Capacitive Load for several values of ROUT. 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. OUTPUT CURRENT LIMIT The output current of the OPA164x series is limited by internal circuitry to +36mA/–30mA (sourcing/sinking), to protect the device if the output is accidentally shorted. This short-circuit current depends on temperature, as shown in Figure 28. Although it is uncommon for most modern audio applications to require 600Ω load drive capability, many audio op amp applications continue to specify the total harmonic distortion (THD+N) at 600Ω load for comparative purposes. Figure 7 and Figure 9 provide typical THD+N measurement curves for the OPA164x series, where the output drives a 3VRMS signal into a 600Ω load. However, it should be noted that correct device operation cannot be ensured when driving 600Ω loads at full supply. Depending on supply voltage and temperature, it may well trigger the output current limit circuitry of the device. POWER DISSIPATION AND THERMAL PROTECTION The OPA164x series of op amps are capable of driving 2kΩ loads with power-supply voltages of up to ±18V over the specified temperature range. In a single-supply configuration, where the load is connected to the negative supply voltage, the minimum load resistance is 2.8kΩ at a supply voltage of +36V. For lower supply voltages (either single-supply or symmetrical supplies), a lower load resistance may be used, as long as the output current does not exceed 13mA; otherwise, the device short-circuit current protection circuit may activate. Internal power dissipation increases when operating at high supply voltages. Copper leadframe construction used in the OPA1641, OPA1642, and OPA1644 series devices improves heat dissipation compared to conventional materials. PCB layout can also help reduce a possible increase in junction Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 13 OPA1641 OPA1642 OPA1644 SBOS484 – DECEMBER 2009 www.ti.com temperature. Wide copper traces help dissipate the heat by acting as an additional heatsink. Temperature rise can be further minimized by soldering the devices directly to the PCB rather than using a socket. Although the output current is limited by internal protection circuitry, accidental shorting of one or more output channels of a device can result in excessive heating. For instance, when an output is shorted to mid-supply, the typical short-circuit current of 36mA leads to an internal power dissipation of over 600mW at a supply of ±18V. In case of a dual OPA1642 in an MSOP-8 package (thermal resistance θJA = 180°C/W), such a power dissipation would lead the die temperature to be 220°C above ambient temperature, when both channels are shorted. This temperature increase would destroy the device. In order to prevent such excessive heating that can destroy the device, the OPA164x series has an internal thermal shutdown circuit, which shuts down the device if the die temperature exceeds approximately +180°C. Once this thermal shutdown circuit activates, a built-in hysteresis of 15°C ensures that the die temperature must drop to about +165°C before the device switches on again. 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. It is helpful to have a good understanding of this basic ESD circuitry and its relevance to an electrical overstress event. Figure 35 illustrates the ESD circuits contained in the OPA164x 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. 14 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 OPA164x 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. When the operational amplifier connects into a circuit such as the one Figure 35 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. Figure 35 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 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. Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 OPA1641 OPA1642 OPA1644 www.ti.com SBOS484 – DECEMBER 2009 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. 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 35. 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. (2) TVS RF +V +VS OPA1641 RI ESD CurrentSteering Diodes -In (3) RS +In Op-Amp Core Edge-Triggered ESD Absorption Circuit ID VIN Out RL (1) -V -VS (2) TVS (1) VIN = +VS + 500mV. (2) TVS: +VS(max) > VTVSBR (Min) > +VS (3) Suggested value approximately 1kΩ. Figure 35. Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): OPA1641 OPA1642 OPA1644 15 PACKAGE OPTION ADDENDUM www.ti.com 1-Jan-2010 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty OPA1641AID ACTIVE SOIC D 8 OPA1641AIDR ACTIVE SOIC D 8 OPA1642AID ACTIVE SOIC D 8 75 OPA1642AIDGKR PREVIEW MSOP DGK 8 OPA1642AIDGKT PREVIEW MSOP DGK 8 OPA1642AIDR ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) 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 TBD Call TI Call TI 250 TBD Call TI Call TI CU NIPDAU Level-2-260C-1 YEAR OPA1644AID PREVIEW SOIC D 14 75 TBD Call TI Call TI OPA1644AIDR PREVIEW SOIC D 14 2500 TBD Call TI Call TI OPA1644AIPW PREVIEW TSSOP PW 14 90 TBD Call TI Call TI OPA1644AIPWR PREVIEW TSSOP PW 14 2000 TBD Call TI Call TI (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. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 MECHANICAL DATA MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°– 8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion not to exceed 0,15. Falls within JEDEC MO-153 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 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. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Amplifiers Data Converters DLP® Products DSP Clocks and Timers Interface Logic Power Mgmt Microcontrollers RFID RF/IF and ZigBee® Solutions amplifier.ti.com dataconverter.ti.com www.dlp.com dsp.ti.com www.ti.com/clocks interface.ti.com logic.ti.com power.ti.com microcontroller.ti.com www.ti-rfid.com www.ti.com/lprf Applications Audio Automotive Broadband Digital Control Medical Military Optical Networking Security Telephony Video & Imaging Wireless www.ti.com/audio www.ti.com/automotive www.ti.com/broadband www.ti.com/digitalcontrol www.ti.com/medical www.ti.com/military www.ti.com/opticalnetwork www.ti.com/security www.ti.com/telephony www.ti.com/video www.ti.com/wireless Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2009, Texas Instruments Incorporated