OPA1602 OPA1604 Burr-Brown Audio SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com ™ High-Performance, Bipolar-Input AUDIO OPERATIONAL AMPLIFIERS Check for Samples: OPA1602, OPA1604 FEATURES DESCRIPTION • • • • • • • • The OPA1602 and OPA1604 bipolar-input operational amplifiers achieve very low 2.5nV/√Hz noise density with an ultralow distortion of 0.00003% at 1kHz. The OPA1602 and OPA1604 series of op amps offer rail-to-rail output swing to within 600mV with 2kΩ load, which increases headroom and maximizes dynamic range. These devices also have a high output drive capability of ±30mA. 1 234 • • • SUPERIOR SOUND QUALITY ULTRALOW NOISE: 2.5nV/√Hz at 1kHz ULTRALOW DISTORTION: 0.00003% at 1kHz HIGH SLEW RATE: 20V/μs WIDE BANDWIDTH: 35MHz (G = +1) HIGH OPEN-LOOP GAIN: 120dB UNITY GAIN STABLE LOW QUIESCENT CURRENT: 2.6mA PER CHANNEL RAIL-TO-RAIL OUTPUT WIDE SUPPLY RANGE: ±2.25V to ±18V DUAL AND QUAD VERSIONS AVAILABLE These devices operate over a very wide supply range of ±2.25V to ±18V, on only 2.6mA of supply current per channel. The OPA1602 and OPA1604 are unity-gain stable and provide excellent dynamic behavior over a wide range of load conditions. These devices also feature completely independent circuitry for lowest crosstalk and freedom from interactions between channels, even when overdriven or overloaded. APPLICATIONS • • • • • PROFESSIONAL AUDIO EQUIPMENT BROADCAST STUDIO EQUIPMENT ANALOG AND DIGITAL MIXERS HIGH-END A/V RECEIVERS HIGH-END BLU-RAY™ PLAYERS The OPA1602 and OPA1604 from –40°C to +85°C. SoundPlus™ are specified V+ Pre-Output Driver OUT IN- IN+ V- 1 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 Association. 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 © 2011, Texas Instruments Incorporated OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 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 (V–) – 0.5 to (V+) + 0.5 V ±10 mA VS = (V+) – (V–) Supply Voltage Input Voltage Input Current (All pins except power-supply pins) Output Short-Circuit (2) Continuous Operating Temperature –55 to +125 °C Storage Temperature –65 to +150 °C Junction Temperature 200 °C Human Body Model (HBM) 4 kV Charged Device Model (CDM) 1 kV 200 V ESD Ratings Machine Model (MM) (1) (2) 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) PRODUCT PACKAGE-LEAD PACKAGE DESIGNATOR PACKAGE MARKING SO-8 D O1602A MSOP-8 DGK OCKQ SO-14 D O1604A TSSOP-14 PW O1604A OPA1602 OPA1604 (1) 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 OPA1602 SO-8, MSOP-8 (TOP VIEW) OUT A 1 -IN A 2 +IN A 3 V- 4 A B OPA1604 SO-14, TSSOP-14 (TOP VIEW) 8 V+ Out A 1 7 OUT B -In A 2 6 -IN B +In A 5 +IN B 14 Out D 13 -In D 3 12 +In D V+ 4 11 V- + In B 5 10 + In C A B D C -In B 6 9 -In C Out B 7 8 Out C 2 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com ELECTRICAL CHARACTERISTICS: VS = ±2.25V to ±18V At TA = +25°C and RL = 2kΩ, unless otherwise noted. VCM = VOUT = midsupply, unless otherwise noted. OPA1602, OPA1604 PARAMETER CONDITIONS MIN TYP MAX UNIT AUDIO PERFORMANCE Total Harmonic Distortion + Noise Intermodulation Distortion THD+N IMD G = +1, f = 1kHz, VO = 3VRMS 0.00003 % –130 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) 0.00003 % –130 dB 0.00003 % –130 dB 0.00003 % –130 dB MHz FREQUENCY RESPONSE Gain-Bandwidth Product GBW G = +1 35 SR G = –1 20 V/μs Full Power Bandwidth (1) VO = 1VP 3 MHz Overload Recovery Time G = –10 1 μs Slew Rate NOISE f = 20Hz to 20kHz 2.5 μVPP Input Voltage Noise Density en f = 100Hz 2.5 nV/√Hz f = 1kHz 2.5 nV/√Hz Input Current Noise Density In f = 100Hz 2.2 pA/√Hz f = 1kHz 1.8 pA/√Hz Input Voltage Noise OFFSET VOLTAGE VS = ±15V ±0.1 ±1 mV VS = ±2.25V to ±18V 0.5 2 μV/V f = 1kHz -130 IB VCM = 0V ±20 ±200 nA IOS VCM = 0V ±20 ±200 nA Input Offset Voltage VOS vs Power Supply PSRR Channel Separation (Dual and Quad) dB INPUT BIAS CURRENT Input Bias Current Input Offset Current INPUT VOLTAGE RANGE Common-Mode Voltage Range VCM Common-Mode Rejection Ratio CMRR (V+) – 2 (V–) + 2 V (V–) + 2V ≤ VCM ≤ (V+) – 2V, VS ≥ ±5V 114 120 dB (V–) + 2V ≤ VCM ≤ (V+) – 2V, VS < ±5V 106 120 dB INPUT IMPEDANCE Differential Common-Mode 20k || 2 Ω || pF 109 || 2.5 Ω || pF OPEN-LOOP GAIN Open-Loop Voltage Gain AOL (V–) + 0.6V ≤ VO ≤ (V+) – 0.6V, RL = 2kΩ, VS ≥ ±5V 114 120 dB (V–) + 0.6V ≤ VO ≤ (V+) – 0.6V, RL = 2kΩ, VS < ±5V 106 114 dB RL = 2kΩ, AOL ≥ 114dB, VS ≥ ±5V (V–) + 0.6 (V+) – 0.6 RL = 2kΩ, AOL ≥ 106dB, VS < ±5V (V–) + 0.6 (V+) – 0.6 OUTPUT Voltage Output Output Current VOUT IOUT Open-Loop Output Impedance ZO Short-Circuit Current ISC Capacitive Load Drive (1) See Typical Characteristics f = 1MHz CLOAD V V mA 25 Ω +70/–60 mA See Typical Characteristics pF Full-power bandwidth = SR/(2π × VP), where SR = slew rate. 3 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 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. OPA1602, OPA1604 PARAMETER CONDITIONS MIN TYP MAX UNIT ±18 V 3.2 mA POWER SUPPLY Specified Voltage VS Quiescent Current (per channel) IQ ±2.25 IOUT = 0A 2.6 TEMPERATURE RANGE Specified Range –40 +85 °C Operating Range –55 +125 °C THERMAL INFORMATION OPA1602 THERMAL METRIC (1) OPA1602 D DGK 8 PINS 8 PINS θJA Junction-to-ambient thermal resistance 154.7 105.4 θJCtop Junction-to-case (top) thermal resistance 49.7 58.6 θJB Junction-to-board thermal resistance 107.9 64.2 ψJT Junction-to-top characterization parameter 2.5 14.1 ψJB Junction-to-board characterization parameter 106.7 66.5 θJCbot Junction-to-case (bottom) thermal resistance — — (1) UNITS °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. THERMAL INFORMATION OPA1604 THERMAL METRIC (1) OPA1604 D PW 14 PINS 14 PINS θJA Junction-to-ambient thermal resistance TBD TBD θJCtop Junction-to-case (top) thermal resistance TBD TBD θJB Junction-to-board thermal resistance TBD TBD ψJT Junction-to-top characterization parameter TBD TBD ψJB Junction-to-board characterization parameter TBD TBD θJCbot Junction-to-case (bottom) thermal resistance TBD TBD (1) UNITS °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. 4 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com 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 10 50nV/div Voltage Noise Density (nV/?Hz) Input Bias Current Noise (pA/?Hz) 100 Voltage Noise Density 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 15 10k VS = ±15V 1k RS 100 10 OPA1642 10 7.5 VS = ±5V 5 2.5 Resistor Noise 1 100 1k 2 EO = 2 Maximum output voltage without slewrate induced distortion 12.5 OPA160x EO Output Voltage (VP) Voltage Noise Spectral Density, EO (nV/?Hz) VOLTAGE NOISE vs SOURCE RESISTANCE VS = ±2.25V 2 en + (in RS) + 4kTRS 10k 100k 0 10k 1M 100k Source Resistance, RS (W) Figure 3. GAIN AND PHASE vs FREQUENCY CLOSED-LOOP GAIN vs FREQUENCY 25 180 20 120 Gain 100 90 40 Phase 45 0 10 Gain (dB) 60 Phase (degrees) 80 G = +10 15 135 20 10M Figure 4. 140 Gain (dB) 1M Frequency (Hz) G = +1 5 0 -5 -10 G = -1 -15 -20 -20 10 100 1k 10k 100k 1M 10M 0 100M -25 100k Frequency (Hz) 1M 10M 100M Frequency (Hz) Figure 5. Figure 6. 5 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. THD+N RATIO vs FREQUENCY THD+N RATIO vs FREQUENCY 0.00001 -120 RL = 600W VOUT = 3VRMS BW = 80kHz 10 RL = 2kW Total Harmonic Distortion + Noise (%) Total Harmonic Distortion + Noise (%) 0.0001 G = -1, RL = 2kW G = +10, RL = 600W G = +10, RL = 2kW 0.01 -140 100 1k RSOURCE OPA1602 -15V 0.001 RL -120 VOUT = 3VRMS, BW = 80kHz 0.00001 10 10k 20k 100 1k THD+N RATIO vs FREQUENCY THD+N RATIO vs FREQUENCY RL = 600W -120 0.0001 RL = 2kW VOUT = 3VRMS BW > 500kHz Total Harmonic Distortion + Noise (%) Total Harmonic Distortion + Noise (%) -100 0.001 0.01 -140 1k 10k RSOURCE OPA1602 -15V 0.001 RL -120 VOUT = 3VRMS BW > 500kHz 10 -140 100 1k Frequency (Hz) Figure 10. THD+N RATIO vs OUTPUT AMPLITUDE INTERMODULATION DISTORTION vs OUTPUT AMPLITUDE RL = 600W 0.0001 1kHz Signal BW = 80kHz RSOURCE = 0W -120 RL = 2kW -140 0.00001 1 10 20 Intermodulation Distortion (%) -100 -60 G = +1 SMPTE/DIN Two-Tone, 4:1 (60Hz and 7kHz) 0.01 DIM30 (3kHz square wave, 15kHz sine wave) 0.001 -80 -100 -120 0.0001 -140 0.00001 CCIF Twin-Tone (19kHz and 20kHz) Total Harmonic Distortion + Noise (dB) 0.1 -80 G = +1, RL = 600W G = +1, RL = 2kW G = -1, RL = 600W G = -1, RL = 2kW G = +10, RL = 600W G = +10, RL = 2kW Total Harmonic Distortion (dB) Total Harmonic Distortion + Noise (%) 100k Frequency (Hz) 0.01 0.1 10k Figure 9. 0.001 -100 0.0001 0.00001 100k -80 RS = 0W RS = 300W RS = 600W RS = 1kW +15V Total Harmonic Distortion + Noise (dB) G = -1, RL = 2kW G = +10, RL = 600W G = +10, RL = 2kW Total Harmonic Distortion + Noise (dB) -80 100 -140 20k Figure 8. 0.01 10 10k Frequency (Hz) Figure 7. 0.00001 -100 0.0001 Frequency (Hz) G = +1, RL = 600W G = +1, RL = 2kW G = -1, RL = 600W -80 RS = 0W RS = 300W RS = 600W RS = 1kW +15V Total Harmonic Distortion + Noise (dB) G = +1, RL = 600W G = +1, RL = 2kW G = -1, RL = 600W Total Harmonic Distortion + Noise (dB) -100 0.001 -160 0.000001 0.1 1 10 20 Output Amplitude (VRMS) Output Amplitude (VRMS) Figure 11. Figure 12. 6 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. CHANNEL SEPARATION vs FREQUENCY Channel Separation (dB) -105 CMRR AND PSRR vs FREQUENCY (Referred to Input) 140 VO = 3VRMS G = +1 Common-Mode Rejection Ratio (dB) -100 -110 -115 -120 RL = 600W -125 -130 -135 RL = 2kW -140 RL = 5kW -145 -150 CMRR 120 100 -PSRR 80 60 +PSRR 40 20 0 10 100 1k 10k 100k 1 10 100 1k Frequency (Hz) 10k 100k 1M 10M Figure 13. Figure 14. SMALL-SIGNAL STEP RESPONSE (100mV) SMALL-SIGNAL STEP RESPONSE (100mV) G = -1 CL = 50pF 20mV/div G = +1 CL = 50pF 20mV/div 100M Frequency (Hz) +15V OPA1602 RF RI = 2kW = 2kW +15V OPA1602 -15V RL CL CL -15V Time (0.1ms/div) Time (0.1ms/div) Figure 15. Figure 16. LARGE-SIGNAL STEP RESPONSE LARGE-SIGNAL STEP RESPONSE G = -1 CL = 50pF G = +1 CL = 50pF 2V/div 2V/div RF = 0W RF = 100W See Application Information, Input Protection section Time (1ms/div) Time (1ms/div) Figure 17. Figure 18. 7 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 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) 50 50 G = -1 G = +1 RS = 0W RS = 0W +15V 40 RF = 2kW RI = 2kW 40 RS +15V RS RL -15V 30 Overshoot (%) Overshoot (%) OPA1602 CL RS = 25W 20 OPA1602 RS = 25W 30 CL -15V 20 RS = 50W 10 10 RS = 50W 0 0 0 100 200 300 400 500 0 600 100 200 300 400 500 600 700 800 900 1000 Capacitive Load (pF) Capacitive Load (pF) Figure 19. Figure 20. SMALL-SIGNAL OVERSHOOT vs FEEDBACK CAPACITOR (100mV Output Step) OPEN-LOOP GAIN vs TEMPERATURE 50 2 RL = 2kW CF RF = 2kW RI = 2kW 40 1.5 RS 30 AOL (mV/V) Overshoot (%) +15V OPA1602 CL -15V 20 G = -1 RI = RF = 2kW R S = 0W CL = 100pF 10 0 0 0.5 1 0.5 0 1 1.5 2 2.5 3 4 3.5 -40 10 -15 Feedback Capacitor, CF (pF) Figure 21. 60 85 Figure 22. IB AND IOS vs TEMPERATURE IB AND IOS vs COMMON-MODE VOLTAGE 40 10 Average of 60 Units VS = ±18V 30 5 -IOS -5 -10 -IB -15 Common-Mode Range 20 0 IB and IOS (nA) IB and IOS Current (nA) 35 Temperature (°C) 10 0 -10 IOS -IB -20 -20 -30 -25 +IB -30 -50 -25 0 25 50 +IB -40 75 100 125 -18 -14 -10 -6 -2 2 6 10 14 18 Common-Mode Voltage (V) Temperature (°C) Figure 23. Figure 24. 8 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) At TA = +25°C, VS = ±15V, and RL = 2kΩ, unless otherwise noted. QUIESCENT CURRENT vs TEMPERATURE QUIESCENT CURRENT vs SUPPLY VOLTAGE 4 3 2.9 3.5 2.8 2.7 IQ (mA) IQ (mA) 3 2.5 2 2.6 2.5 2.4 2.3 2.2 1.5 Specified Operating Temperature Range Specified Supply-Voltage Range 2.1 1 2 -40 -15 10 35 60 85 0 110 4 8 12 16 20 Figure 25. 32 36 SHORT-CIRCUIT CURRENT vs TEMPERATURE 75 0.3 +ISC 70 0.25 VS = ±18V 65 OPA1604 60 0.2 ISC (mA) DIQ, per Channel (mA) 28 Figure 26. IQ WARMUP (Difference from IQ at Startup, Per Channel) OPA1602 0.15 55 -ISC 50 45 0.1 40 0.05 35 30 0 0 60 120 180 240 300 360 -50 -25 0 25 50 75 100 125 Temperature (°C) Time (s) Figure 27. Figure 28. OUTPUT VOLTAGE vs OUTPUT CURRENT OPEN-LOOP OUTPUT IMPEDANCE vs FREQUENCY 18 10k 16 VS = ±18V 14 1k +125°C +85°C +25°C 0°C -25°C -40°C 12 10 -10 -12 ZO (W) Output Voltage Swing (V) 24 Supply Voltage (V) Temperature (°C) 100 10 -14 -16 1 -18 20 30 40 50 60 70 80 10 100 Output Current (mA) 1k 10k 100k 1M 10M 100M Frequency (Hz) Figure 29. Figure 30. 9 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com APPLICATION INFORMATION applications do not require equal positive and negative output voltage swing. With the OPA160x 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. The OPA1602 and OPA1604 are unity-gain stable, precision dual and quad op amps with very low noise. Applications with noisy or high-impedance power supplies require decoupling capacitors close to the device pins. In most cases, 0.1μF capacitors are adequate. Figure 31 shows a simplified schematic of the OPA160x (one channel shown). 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 significantly with operating voltage or temperature are shown in the Typical Characteristics. OPERATING VOLTAGE The OPA160x series op amps operate from ±2.25V to ±18V supplies while maintaining excellent performance. The OPA160x series can operate with as little as +4.5V between the supplies and with up to +36V between the supplies. However, some V+ Pre-Output Driver OUT IN- IN+ V- Figure 31. OPA160x Simplified Schematic 10 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com The input terminals of the OPA1602 and OPA1604 are protected from excessive differential voltage with back-to-back diodes, as Figure 32 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 resistor degrades the low-noise performance of the OPA160x and is examined in the following Noise Performance section. Figure 32 shows an example configuration when both current-limiting input and feeback resistors are used. The equation in Figure 33 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, EO (nV/?Hz) INPUT PROTECTION 10k OPA160x EO 1k RS 100 10 OPA1642 Resistor Noise 1 100 1k 2 2 2 EO = en + (in RS) + 4kTRS 10k 100k 1M Source Resistance, RS (W) RF Figure 33. Noise Performance of the OPA160x in Unity-Gain Buffer Configuration - OPA160x RI Input Output + Figure 32. Pulsed Operation NOISE PERFORMANCE Figure 33 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 OPA160x (GBW = 35MHz, 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, current noise is negligible, and voltage noise generally dominates. The low voltage noise of the OPA160x series op amps makes them a better choice for low source impedances of less than 1kΩ. BASIC NOISE CALCULATIONS 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 33 plots this equation. The source impedance is usually fixed; consequently, select the op amp and the feedback resistors to minimize the respective contributions to the total noise. Figure 34 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. 11 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com A) Noise in Noninverting Gain Configuration 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 R2 2 EO = 1 + R1 RS VS Note: R1 + RS e n2 + 2 R2 R 1 + RS e12 + e22 + 2 R2 R 1 + RS e s2 EO Where eS = 4kTRS = thermal noise of RS e1 = 4kTR1 = thermal noise of R1 e2 = 4kTR2 = thermal noise of R2 For the OPA160x series of op amps at 1kHz, en = 2.5nV/√Hz and in = 1.8pA√Hz. Figure 34. Noise Calculation in Gain Configurations 12 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com TOTAL HARMONIC DISTORTION MEASUREMENTS The OPA160x 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 the OPA160x series op amps is below the measurement limit of many commercially available distortion analyzers. However, a special test circuit (such as Figure 35 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 35 shows a circuit that causes the op amp distortion to be gained up (refer to the table in Figure 35 for the distortion gain factor for various signal gains). 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 the distortion gain factor, thus extending the resolution by the same amount. 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 The 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. CAPACITIVE LOADS The dynamic characteristics of the OPA1602 and OPA1604 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. This small series resistor also prevents excess power dissipation if the output of the device becomes shorted. Figure 19 illustrates a graph 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 SIGNAL DISTORTION GAIN GAIN R3 Signal Gain = 1+ OPA160x VO = 3VRMS R2 R1 Distortion Gain = 1+ R2 R1 II R3 Generator Output R1 R2 R3 ¥ 1kW 10W +1 101 -1 101 4.99kW 4.99kW 49.9W +10 110 549W 4.99kW 49.9W Analyzer Input Audio Precision System Two(1) with PC Controller Load (1) For measurement bandwidth, see Figure 7 through Figure 12. Figure 35. Distortion Test Circuit 13 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com POWER DISSIPATION The OPA1602 and OPA1604 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 OPA160x 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. It is helpful to have a good understanding of this basic ESD circuitry and its relevance to an electrical overstress event. Figure 36 illustrates the ESD circuits contained in the OPA160x (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 internal to the OPA160x triggers when a fast ESD voltage pulse is impressed across the supply pins. Once triggered, it quickly activates, clamping the ESD pulse to a safe voltage level. When the operational amplifier connects into a circuit such as that illustrated in Figure 36, 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 36 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. In extreme but rare cases, the absorption device triggers on while +VS and –VS are applied. If this event happens, a 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. 14 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com 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 36. 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. TVS RF +V +VS OPA160x RI ESD CurrentSteering Diodes -In RS +In Op-Amp Core Edge-Triggered ESD Absorption Circuit ID VIN Out RL (1) -V -VS TVS (1) VIN = +VS + 500mV. Figure 36. Equivalent Internal ESD Circuitry and Its Relation to a Typical Circuit Application (Single Channel Shown) 15 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 OPA1602 OPA1604 SBOS474A – APRIL 2011 – REVISED JUNE 2011 www.ti.com APPLICATION CIRCUIT An additional application idea is shown in Figure 37. 820W 2200pF +VA (+15V) 0.1mF 330W IOUTL+ OPA160x 2700pF -VA (-15V) 680W 620W Audio DAC with Differential Current Outputs 0.1mF +VA (+15V) 0.1mF 100W 820W OPA160x 8200pF 2200pF +VA (+15V) L Ch Output -VA (-15V) 0.1mF 0.1mF 680W 620W IOUTLOPA160x 330W 2700pF -VA (-15V) 0.1mF Figure 37. Audio DAC I/V Converter and Output Filter 16 Copyright © 2011, Texas Instruments Incorporated Product Folder Link(s): OPA1602 OPA1604 PACKAGE OPTION ADDENDUM www.ti.com 23-Jun-2011 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty 75 Green (RoHS & no Sb/Br) OPA1602AID ACTIVE SOIC D 8 Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) CU NIPDAU Level-2-260C-1 YEAR OPA1602AIDGK PREVIEW MSOP DGK 8 80 TBD Call TI Call TI OPA1602AIDGKR PREVIEW MSOP DGK 8 2500 TBD Call TI Call TI OPA1602AIDR ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR (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 21-Jun-2011 TAPE AND REEL INFORMATION *All dimensions are nominal Device OPA1602AIDR Package Package Pins Type Drawing SOIC D 8 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 2500 330.0 12.4 Pack Materials-Page 1 6.4 B0 (mm) K0 (mm) P1 (mm) 5.2 2.1 8.0 W Pin1 (mm) Quadrant 12.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 21-Jun-2011 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) OPA1602AIDR 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. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. 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