Dual JFET Input Audio Operational Amplifier General Description Key Specifications The LME49880 is part of the ultra-low distortion, low noise, high slew rate operational amplifier series optimized and fully specified for high performance, high fidelity application. The LME49880 is developed in JFET technology and reducing the flicker noise as well as the noise corner frequency significantly. It combines low voltage noise density (7nV/√Hz) with very low THD+N (0.00003%). The LME49880 has a high slew rate of ±17 V/μs and an output current capability of ±22mA. It drives 600Ω loads to within 1.3V of either power supply voltage. The LME49880 has a wide supply range of ±5V to ±17V. Its outstanding GAIN (120dB), and low input bias current (5pA) give the amplifier excellent operational amplifier DC performance. The LME49880 is unity gain stable and capable of driving complex loads with values as high as 100pF. It is available in an 8-lead narrow body PSOP. ■ Input Bias Current 5pA (typ) ■ Power Supply Voltage Range ±5V to ±17V ■ THD+N (AV = 1, VOUT = 3VRMS, fIN = 1kHz) RL = 2kΩ 0.00003% (typ) RL = 600Ω 0.00003% (typ) ■ Slew Rate ±17V/μs (typ) ■ Gain Bandwidth Product 25MHz (typ) ■ Open Loop Gain (RL = 600Ω) 115dB (typ) ■ Input Noise Density 7nV/√Hz (typ) ■ Input Offset Voltage 5mV (typ) ■ CMRR 110dB (typ) Features ■ Easily drives 600Ω loads ■ Output short circuit protection Applications ■ ■ ■ ■ ■ Ultra high quality audio signal processing Preamplifier Spectrum analyzers Ultrasound preamplifier Active filters Typical Application VCC = ±15V, VO = 3VRMS, RL = 600Ω 300596t9 FIGURE 1: Current Noise and Voltage Spectral Density 300596s0 FIGURE 2: THD+N vs Frequency Overture® is a registered trademark of National Semiconductor. © 2010 National Semiconductor Corporation 300596 www.national.com LME49880 Dual FET Input Audio Operational Amplifier April 22, 2010 LME49880 Overture® E-Series LME49880 Connection Diagram 30059655 Order Number LME49880MR See NS Package Number — MRA08B Ordering Information Ordering Information Order Number Package Package DWG # Transport Media MSL Level Green Status LME49880MR 8 Ld PSOP with Exposed Pad MRA08B 95 units 3 RoHS and noSb/Br LME49880MRX 8 Ld PSOP with Exposed Pad MRA08B 2500 units on rail 3 RoHS and noSb/Br www.national.com 2 If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Power Supply Voltage (VS = V+ - V-) Storage Temperature Input Voltage θJA (PSOP) Solder Information Infrared or Convection (20 sec) 36V −65°C to 150°C Output Short Circuit (Note 3) Power Dissipation ESD Rating (Note 4) ESD Rating (Note 5) Operating Ratings (V-) - 0.3V to (V+) + 0.3V Continuous Internally Limited 2000V 200V Electrical Characteristics (Note 2) 1000V 150°C 55°C/W 260°C (Note 1) Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage Range –40°C ≤ TA ≤ 85°C ±5V ≤ VS ≤ ±17V The following specifications apply for VS = ±15V, TA = 25°C, unless otherwise specified. LME49880 Symbol Parameter Conditions Typical Limit (Note 6) (Note 7) 0.00003 0.00003 0.00009 Unit s (Limits) AV = 1, VOUT = 3VRMS THD+N Total Harmonic Distortion + Noise RL = 2kΩ RL = 600Ω % (max) GBWP Gain Bandwidth Product AV = 1k, RL = 2k 25 19 MHz (min) SR Slew Rate RL = 2k ±17 ±12 V/μs (min) Settling time AV = –1, 10V step, CL = 100pF 0.1% error range 0.8 Equivalent Input Noise Voltage fBW = 20Hz to 20kHz 0.7 1.6 μVRMS Equivalent Input Noise Density f = 1kHz f = 10Hz 7 16 11 nV/√Hz iN Current Noise Density f = 1kHz 6 VOS Offset Voltage ts eN Average Input Offset Voltage Drift ΔVOS/ΔTemp vs Temperature ±5 –40°C ≤ TA ≤ 85°C 3 110 PSRR Power Supply Rejection Ratio VCC = ±5V to ±15V IB Input Bias Current VCM = 0V IOS Input Offset Current VCM = 0V 5 (max) fA/√Hz ±10 mV (max) μV/°C dB 150 pA (max) 2 100 pA (max) (V+) –5V (V-) +5V V (min) –10V<Vcm<10V 110 90 dB (min) –10V<Vout<10V, RL = 600Ω 115 100 dB (min) –10V<Vout<10V, RL = 2kΩ 120 100 dB (min) –10V<Vout<10V, RL = 10kΩ 120 100 dB (min) RL = 600Ω ±13.2 ±12.0 V (min) RL = 2kΩ ±13.2 ±12.5 V (min) RL = 10kΩ ±13.2 ±12.5 V (min) Common-Mode Input Voltage Range CMRR > 55dB CMRR Common-Mode Rejection AVOL Open Loop Voltage Gain Maximum Output Voltage Swing (max) +11.5 –11.5 VIN-CM VOUTMAX μs RL = 600Ω, VS = ±17V IOUT Output Current IOUT-CC Instantaneous Short Circuit Current ROUT Output Impedance fIN = 10kHz, Open-Loop IS Total Quiescent Current IOUT = 0mA 14 3 ±26 mA ±48 mA 15 Ω 18 mA (max) www.national.com LME49880 ESD Rating (Note 8) Junction Temperature Thermal Resistance Absolute Maximum Ratings (Note 1) LME49880 Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: The Electrical Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed. Note 3: Amplifier output connected to GND, any number of amplifiers within a package. Note 4: Human body model, applicable std. JESD22-A114C. Note 5: Machine model, applicable std. JESD22-A115-A. Note 6: Typical values represent most likely parametric norms at TA = +25ºC, and at the Recommended Operation Conditions at the time of product characterization and are not guaranteed. Note 7: Datasheet min/max specification limits are guaranteed by test or statistical analysis. Note 8: Charge device model, applicable std JESD22-C101-A. www.national.com 4 LME49880 Typical Performance Characteristics THD+N vs Frequency VCC = 15V, VOUT = 3V RL = 2kΩ THD+N vs Frequency VCC = 15V, VOUT = 3V RL = 600Ω 300596r9 300596s0 THD+N vs Frequency VCC = 18V, VOUT = 3V RL = 2kΩ THD+N vs Frequency VCC = 18V, VOUT = 3V RL = 600Ω 300596s1 300596s2 THD+N vs Output Voltage VCC = 15V RL = 2kΩ THD+N vs Output Voltage VCC = 15V RL = 600Ω 300596s3 300596s4 5 www.national.com LME49880 THD+N vs Output Voltage VCC = 18V RL = 2kΩ THD+N vs Output Voltage VCC = 18V RL = 600Ω 300596s5 300596s6 +PSRR vs Frequency −PSRR vs Frequency 300596s7 300596t0 CMRR vs Frequency Current Noise vs Frequency 300596t7 300596s8 www.national.com 6 LME49880 Voltage Noise vs Frequency 300596t8 7 www.national.com LME49880 PSOP EXPOSED PAD PACKAGE The LME49880 has an exposed pad on the bottom side of the IC package. Connect the exposed pad to pin 4 (V-) of the IC. The PCB footprint for the exposed pad should be a open polygon of copper to provide a good thermal path away from the LME49880. Use multiple vias on the exposed pad to create better thermal conductivity. Do not route traces below the exposed pad as they risk shorting to the exposed pad. Application Hints OUTPUT DRIVE AND STABILITY The LME49880 is unity gain stable within the part’s commonmode range. Some instabilities may occur near the limit of the common-mode range. It can drive resistive load 600Ω with output circuit with a typical 26mA. Capacitive loads up to 100pF will cause little change in the phase characteristics of the amplifiers and are therefore allowable. Capacitive loads greater than 100pF must be isolated from the output. The most straight forward way to do this is to put a resistor in series with the output. This resistor will also prevent excess power dissipation if the output is accidentally shorted. The internal short-circuit protection of LME49880 also prevent the device from damage when the either outputs are being shorted. The effective load impedance (including feedback resistance) should be kept above 600Ω for fast settling. Load capacitance should also be minimized if good settling time is to be optimized. Large feedback resistors will make the circuit more susceptible to stray capacitance, so in high-speed applications keep the feedback resistors in the 1kΩ to 2kΩ range whenever practical. OUTPUT COMPENSATION In most of the audio applications, the device will be operated in a room temperature and compensation networks are not necessary. However, the consideration of network as shown in Figure 3 may be taken into account for some of the high performance audio applications such as high speed data conversion or when operating in a relatively low junction temperature. The compensation network will also provide a small improvement in settling time for the response time demanding applications. 300596t3 FIGURE 4: LME49880 Output Compensation Network SUPPLY BYPASSING To achieve a low noise and high-speed audio performance, power supply bypassing is extremely important. Applying multiple bypass capacitors is highly recommended. From experiment results, a 10μF tantalum, 2.2μF ceramic, and a 0.47μF ceramic work well. All bypass capacitors leads should be very short. The ground leads of capacitors should also be separated to reduce the inductance to ground. To obtain the best result, a large ground plane layout technique is recommended and it was applied in the LME49880 evaluation board. 300596r5 FIGURE 3: LME49880 Output Compensation Network www.national.com 8 SETTLING TIME AND SLEW RATE MEASUREMENTS The settling time of LME49880 may be verified using the test circuit in Figure 5. The LME49880 is connected for inverting operation, and the output voltage is summed with the input voltage step. When the LME49880’s output voltage is equal to the input voltage, the voltage on the PROBE 1 will be zero. Any voltage appearing at this point will represent an error. And the settling time is equal to the time required for the error signal displayed on the oscilloscope to decay to less than onehalf the necessary accuracy (See Settling Time – Output Swing photo). For a 10V input signal, settling time to 0.01% (1mV) will occur when the displayed error is less than 0.5mV. Since settling time is strongly dependent on slew rate, settling will be faster for smaller signal swings. The LME49880’s inverting slew rate is faster than its non-inverting slew rate, so 300596r6 FIGURE 5: Settling Time Test Circuit 300596r7 FIGURE 6: Slew Rate Test Circuit 9 www.national.com LME49880 settling will be faster for inverting applications, as well. It is important to note that the oscilloscope input amplifier may be overdriven during a settling time measurement, so the oscilloscope must be capable of recovering from overdrive very quickly. The signal generator used for this measurement must be able to drive 50Ω with a very clean ±10VPP square wave. The Slew Rate of LME49880 tells how fast it responses to a transient or a step input. It may be measured by the test circuit in Figure 6. The Slew Rate of LME49880 is specified in closeloop gain = -1 when the output driving a 1kΩ load at 20VPP. The LME49880 behaves very stable in shape step response and have a minimal ringing in both small and large signal step response (See Typical Performance Characteristic). The slew rate typical value reach as high as ±18V/μS was measured when the output reach -20V refer to the start point when input voltage equals to zero. Application Information LME49880 the error signal (distortion) is amplified by a factor of 101. Although the amplifier’s closed-loop gain is unaltered, the feedback available to correct distortion errors is reduced by 101, which means that measurement resolution increases by 101. To ensure minimum effects on distortion measurements, keep the value of R1 low as shown in Figure 7. This technique is verified by duplicating the measurements with high closed loop gain and/or making the measurements at high frequencies. Doing so produces distortion components that are within the measurement equipment’s capabilities. This datasheet’s THD+N and IMD values were generated using the above described circuit connected to an Audio Precision System Two Cascade. DISTORTION MEASUREMENTS The vanishingly low residual distortion produced by LME49880 is below the capabilities of all commercially available equipment. This makes distortion measurements just slightly more difficult than simply connecting a distortion meter to the amplifier’s inputs and outputs. The solution, however, is quite simple: an additional resistor. Adding this resistor extends the resolution of the distortion measurement equipment. The LME49880’s low residual distortion is an input referred internal error. As shown in Figure 7, adding the 10Ω resistor connected between the amplifier’s inverting and non-inverting inputs changes the amplifier’s noise gain. The result is that 300596k4 FIGURE 7: THD+N and IMD Distortion Test Circuit www.national.com 10 LME49880 Typical Applications Balanced Input Mic Amp 30059643 Illustration is: V0 = 101(V2 − V1) Active Crossover Network for Loudspeaker 300596r8 11 www.national.com LME49880 Revision History Rev Date 1.0 12/16/09 Initial released. 1.01 01/08/10 Input text edits. 1.02 03/22/10 Edited the scaling (Y-axis) on the THD+N curves to match the limits described in the datasheet. www.national.com Description 12 LME49880 Physical Dimensions inches (millimeters) unless otherwise noted Narrow PSOP Package Order Number LME49880MR NS Package Number MRA08B 13 www.national.com LME49880 Dual FET Input Audio Operational Amplifier Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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