LME49610 High Performance, High Fidelity, High Current Audio Buffer General Description Key Specifications The LME49610 is a high performance, low distortion high fidelity 250mA audio buffer. The LME49610 is designed for a wide range of applications. When used inside the feedback loop of an op amp, it increases output current, improves capacitive load drive, and eliminates thermal feedback. The LME49610 offers a pin-selectable bandwidth: a low current, 120MHz bandwidth mode that consumes 13mA and a wide 200MHz bandwidth mode that consumes 19mA. In both modes the LME49610 has a nominal 2000V/μs slew rate. Bandwidth is easily adjusted by either leaving the BW pin unconnected, connecting it to the VEE pin or connecting a resistor between the BW pin and the VEE pin. The LME49610 is fully protected through internal current limit and thermal shutdown. ■ Low THD+N (VOUT = 3VRMS, f = 1kHz, Fig. 2) ■ Slew Rate 0.00003% (typ) 2000V/μs (typ) ■ High Output Current 250mA (typ) ■ Bandwidth BW pin floating 120MHz (typ) BW connected to VEE 200MHz (typ) ■ Supply Voltage Range ±2.25V ≤ VDD ≤ ±22V Features ■ ■ ■ ■ ■ Pin-selectable bandwidth and quiescent current Pure fidelity. Pure performance Short circuit protection Thermal shutdown TO–263 surface-mount package Applications ■ ■ ■ ■ ■ ■ Headphone amplifier output drive stage Line drivers Low power audio amplifiers High-current operational amplifier output stage ATE pin driver buffer Power supply regulator Functional Block Diagram 30042541 FIGURE 1. Functional Block Diagram Boomer® is a registered trademark of National Semiconductor Corporation. © 2009 National Semiconductor Corporation 300425 www.national.com LME49610 High Performance, High Fidelity, High Current Audio Buffer October 28, 2009 LME49610 Connection Diagrams TO-263 Package (Note 9) 30042539 Top View Order Number LME49610TS See NS Package Number TS5B 30042542 Top View U — Wafer fabrication code Z — Assembly plant XY — 2 Digit date code TT — Lot traceability www.national.com 2 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage ESD Rating (Note 4) ESD Rating (Note 5) Storage Temperature Junction Temperature Thermal Resistance 46V 2000V 200V −40°C to +150°C 150°C θJC 4°C/W θJA 65°C/W θJA (Note 3) Soldering Information TO–263 Package (10 seconds) 20°C/W Operating Ratings 260°C (Note 1, Note 2) Temperature Range TMIN ≤ TA ≤ TMAX Supply Voltage −40°C ≤ TA ≤ 85°C ±2.25V to ±22V Electrical Characteristics The following specifications apply for VS = ±22V, fIN = 1kHz, RL = 1kΩ, unless otherwise specified. Typicals and limits apply for TA = 25°C. LME49610 Symbol IQ Parameter Total Quiescent Current Conditions IOUT = 0 BW pin: No connect BW pin: Connected to VEE pin Typical Limit (Note 6) (Note 7) 13 19 15 23 Units (Limits) mA (max) mA (max) AV = 1, VOUT = 3VRMS, THD+N SR Total Harmonic Distortion + Noise (Note 8) Slew Rate RL = 32Ω, BW = 80kHz, closed loop see Figure 2. f = 1kHz f = 20kHz 30 ≤ BW ≤ 180MHz VOUT = 20VP-P, RL = 100Ω 0.000035 0.0005 % % 2000 V/μs 110 120 MHz MHz 180 200 MHz MHz AV = –3dB BW pin: No Connect RL = 100Ω BW Bandwidth RL = 1kΩ BW pin: Connected to VEE pin RL = 100Ω RL = 1kΩ Voltage Noise Density f = 10kHz BW pin: No Connect 3.0 8.5 nV/√Hz (max) f = 10kHz BW pin: Connected to VEE pin 2.7 6.5 nV/√Hz (max) ΔV = 10V, RL = 100Ω ts Settling Time 1% Accuracy BW pin: No connect BW pin: Connected to VEE pin 200 60 ns ns VOUT = ±10V AV Voltage Gain RL = 67Ω 0.93 0.95 0.99 RL = 100Ω RL = 1kΩ 3 0.90 0.92 0.98 V/V (min) V/V (min) V/V (min) www.national.com LME49610 Absolute Maximum Ratings (Note 1, Note LME49610 LME49610 Symbol VOUT Parameter Voltage Output Conditions Typical Limit Units (Limits) (Note 6) (Note 7) Positive IOUT = 10mA IOUT = 100mA IOUT = 150mA VCC –1.2 VCC –1.5 VCC –1.7 VCC –1.4 VCC –1.8 VCC –2.1 V (min) V (min) V (min) Negative IOUT = –10mA IOUT = –100mA IOUT = –150mA VEE +1.2 VEE +1.6 VEE +2.2 VEE +1.4 VEE +1.9 VEE +2.5 V (min) V (min) V (min) IOUT Output Current IOUT-SC Short Circuit Output Current BW pin: No Connect BW pin: Connected to VEE pin ±750 ±750 ±785 mA mA (max) IB Input Bias Current VIN = 0V BW pin: No Connect BW pin: Connected to VEE pin ±1.0 ±3.0 ±2.5 ±5.0 μA (max) μA (max) ZIN Input Impedance RL = 100Ω BW pin: No Connect BW pin: Connected to VEE pin 7.5 5.5 VOS Offset Voltage VOS/°C Offset Voltage vs Temperature V SUPPLY Power Supply Voltage Operating Range ±250 ±17 40°C ≤ TA ≤ +125°C mA MΩ MΩ ±60 mV (max) ±100 μV/°C ±2.25 ±22 V V 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: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LME49610, typical application shown in Figure 2 with |VEE| = VCC = 15V, RL = 32Ω, the total power dissipation is 1.9W. θJA = 20°C/W for the TO-263 package mounted to 16in2 (103.2 cm2) 1oz. copper surface heat sink area. 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: This is the distortion of the LME49610 operating in a closed loop configuration with an LME49710. When operating in an operational amplifier's feedback loop, the amplifier's open loop gain dominates, linearizing the system and determining the overall system distortion. Note 9: The TS5B package is a non-isolated package. The package’s metal back and any heat sink to which it is mounted are connected to the same potential as the –VEE pin. www.national.com 4 Gain vs Frequency vs Quiescent Current VS = ±22V Phase vs Frequency vs Quiescent Current VS = ±22V 30042570 30042571 Gain vs Frequency vs Power Supply Voltage Wide BW Mode (BW pin = VEE) Phase vs Frequency vs Supply Voltage Wide BW Mode (BW pin = VEE) 30042572 30042573 Gain vs Frequency vs Power Supply Voltage Low IQ Mode (BW pin = Float) Phase vs Frequency vs Power Supply Voltage Low IQ Mode (BW pin = Float) 30042574 30042575 5 www.national.com LME49610 Typical Performance Characteristics LME49610 Gain vs Frequency vs RLOAD Wide BW Mode (BW pin = VEE), VS = ±22V Phase vs Frequency vs RLOAD Wide BW Mode (BW pin = VEE), VS = ±22V 30042576 30042577 Gain vs Frequency vs RLOAD Low IQ Mode (BW pin = Float), VS = ±22V Phase vs Frequency vs RLOAD Low IQ Mode (BW pin = Float), VS = ±22V 30042578 30042579 Gain vs Frequency vs Quiescent Current VS = ±15V Phase vs Frequency vs Quiescent Current VS = ±15V 300425a5 30042594 www.national.com 6 Phase vs Frequency vs RLOAD Wide BW Mode (BW pin = VEE), VS = ±15V 300425a2 30042591 Gain vs Frequency vs RLOAD Low IQ Mode (BW pin = Float), VS = ±15V Phase vs Frequency vs RLOAD Low IQ Mode (BW pin = Float), VS = ±15V 300425a1 30042590 +PSRR vs Frequency VS = ±15V and ±22V, Low IQ Mode (BW pin = Float) +PSRR vs Frequency VS = +15V and ±22V, Wide BW Mode (BW pin = VEE) 30042595 30042597 7 www.national.com LME49610 Gain vs Frequency vs RLOAD Wide BW Mode (BW pin = VEE), VS = ±15V LME49610 −PSRR vs Frequency VS = ±15V and ±22V, Wide BW Mode (BW pin = VEE) −PSRR vs Frequency VS = ±15V and ±22V, Low IQ Mode (BW pin = Float) 30042596 30042598 Quiescent Current vs Bandwidth Control Resistance VS = ±15V (Bottom) & VS = ±22V (Top) THD+N vs Output Voltage VS = ±15V, RL = 32Ω, f = 1kHz 300425a6 30042585 Wide BW Noise Curve (BW pin = VEE) Low IQ Noise Curve (BW pin = Float) 30042586 www.national.com 30042587 8 LME49610 Typical Application Diagram 30042540 FIGURE 2. High Performance, High Fidelity LME49610 Audio Buffer Application 9 www.national.com LME49610 The audio input signal is applied to the input jack (HP31 or J1/J2) and dc-coupled to the volume control, VR1. The output signal from VR1’s wiper is applied to the non-inverting input of U2-A, an LME49720 High Performance, High Fidelity audio operational amplifier. U2-A’s signal gain is set by resistors R2 and R4. To allow for a DC-coupled signal path and to ensure minimal output DC voltage regardless of the closed-loop gain, the other half of the U2 is configured as a DC servo. By constantly monitoring U2-A’s output, the servo creates a voltage that compensates for any DC voltage that may be present at the output. A correction voltage is generated and applied to the feedback node at U2-A, pin 2. The servo ensures that the gain at DC is unity. Based on the values shown in Figure 3, the RC combination formed by R11 and C7 sets the servo’s high-pass cutoff at 0.16Hz. This is over two decades below 20Hz, minimizing both amplitude and phase perturbations in the audio frequency band’s lowest frequencies. Application Information HIGH PERFORMANCE, HIGH FIDELITY HEADPHONE AMPLIFIER The LME49610 is the ideal solution for high output, high performance high fidelity headphone amplifiers. When placed in the feedback loop of the LME49710, LME49720 or LME49740 High Performance, High Fidelity audio operational amplifier, the LME49610 is able to drive 32Ω headphones to a dissipation of greater than 500mW at 0.00003% THD+N while operating on ±15V power supply voltages. The circuit schematic for a typical headphone amplifier is shown in Figure 3. Operation The following describes the circuit operation for the headphone amplifier’s Left Channel. The Right Channel operates identically. 30042558 FIGURE 3. LME49610 delivers high output current for this high performance headphone amplifier www.national.com 10 SUPPLY BYPASSING The LME49610 will place great demands on the power supply voltage source when operating in applications that require fast slewing and driving heavy loads. These conditions can create high amplitude transient currents. A power supply’s limited bandwidth can reduce the supply’s ability to supply the needed current demands during these high slew rate conditions. This inability to supply the current demand is further exacerbated by PCB trace or interconnecting wire inductance. The transient current flowing through the inductance can produce voltage transients. For example, the LME49610’s output voltage can slew at a typical 2000V/μs. When driving a 100Ω load, the di/dt current demand is 20 A/μs. This current flowing through an inductance of 50nH (approximately 1.5” of 22 gage wire) will produce a 1V transient. In these and similar situations, place the parallel combination of a solid 5μF to 10μF tantalum capacitor and a ceramic 0.1μF capacitor as close as possible to the device supply pins. Ceramic capacitor have very lower ESR (typically less than 10mΩ) and low ESL when compared to the same valued tantalum capacitor. The ceramic capacitors, therefore, have superior AC performance for bypassing high frequency noise. In less demanding applications that have lighter loads or lower slew rates, the supply bypassing is not as critical. Capacitor values in the range of 0.01μF to 0.1μF are adequate. 30042560 FIGURE 5. Buffer Connections OUTPUT CURRENT The LME49610 can continuously source or sink 250mA. Internal circuitry limits the short circuit output current to approximately ±450mA. For many applications that fully utilize the LME49610’s current source and sink capabilities, thermal dissipation may be the factor that limits the continuous output current. The maximum output voltage swing magnitude varies with junction temperature and output current. Using sufficient PCB copper area as a heatsink when the metal tab of the LME49610’s surface mount TO–263 package is soldered directly to the circuit board reduces thermal impedance. This in turn reduces junction temperature. The PCB copper area should be in the range of 2in2 to 6in2. SIMPLIFIED LME49610 CIRCUIT DIAGRAM The LME49610’s simplified circuit diagram is shown in Figure 4. The diagram shows the LME49610’s complementary emitter follower design, bias circuit and bandwidth adjustment node. THERMAL PROTECTION LME49610 power dissipated will cause the buffer’s junction temperature to rise. A thermal protection circuit in the LME49610 will disable the output when the junction temperature exceeds 150°C. When the thermal protection is activated, the output stage is disabled, allowing the device to cool. The output circuitry is enabled when the junction temperature drops below 150°C. The TO–263 package has excellent thermal characteristics. To minimize thermal impedance, its exposed die attach paddle should be soldered to a circuit board copper area for good heat dissipation. Figure 6 shows typical thermal resistance from junction to ambient as a function of the copper area. The TO–263’s exposed die attach paddle is electrically connected to the VEE power supply pin. 30042559 LOAD IMPEDANCE The LME49610 is stable under any capacitive load when driven by a source that has an impedance of 50Ω or less. When driving capacitive loads, any overshoot that is present on the output signal can be reduced by shunting the load capacitance with a resistor. FIGURE 4. Simplified Circuit Diagram Figure 5 shows the LME49610 connected as an open-loop buffer. The source impedance and optional input resistor, RS, can alter the frequency response. As previously stated, the power supplies should be bypassed with capacitors con11 www.national.com LME49610 nected close to the LME49610’s power supply pins. Capacitor values as low as 0.01μF to 0.1μF will ensure stable operation in lightly loaded applications, but high output current and fast output slewing can demand large current transients from the power supplies. Place a recommended parallel combination of a solid tantalum capacitor in the 5μF to 10μF range and a ceramic 0.1μF capacitor as close as possible to the device supply pins. AUDIO BUFFERS Audio buffers or unity-gain followers, have large current gain and a voltage gain of one. Audio buffers serve many applications that require high input impedance, low output impedance and high output current. They also offer constant gain over a very wide bandwidth. Buffers serve several useful functions, either in stand-alone applications or in tandem with operational amplifiers. In standalone applications, their high input impedance and low output impedance isolates a high impedance source from a low impedance load. LME49610 A ground plane type circuit board layout is best for very high frequency performance results. Bypass the power supply pins (VCC and VEE) with 0.1μF ceramic chip capacitors in parallel with solid tantalum 10μF capacitors placed as close as possible to the respective pins. Source resistance can affect high-frequency peaking and step response overshoot and ringing. Depending on the signal source, source impedance and layout, best nominal response may require an additional resistance of 25Ω to 200Ω in series with the input. Response with some loads (especially capacitive) can be improved with an output series resistor in the range of 10Ω to 150Ω. OVERVOLTAGE PROTECTION If the input-to-output differential voltage exceeds the LME49610’s Absolute Maximum Rating of 3V, the internal diode clamps shown in Figure 1 conduct, diverting current around the compound emitter followers of Q1/Q5 (D1 – D7 for positive input), or around Q2/Q6 (D8 – D14 for negative inputs). Without this clamp, the input transistors Q1/Q2 and Q5/ Q6 will zener and damage the buffer. To ensure that the current flow through the diodes is held to a save level, the internal 200Ω resistor in series with the input limits the current through these clamps. If the additional current that flows during this situation can damage the source that drives the LME49610’s input, add an external resistor in series with the input see Figure 5. THERMAL MANAGEMENT Heat Sinking For some applications, the LME49610 may require a heat sink. The use of a heat sink is dependent on the maximum LME49610 power dissipation and a given application’s maximum ambient temperature. In the TO–263 package, heat sinking the LME49610 is easily accomplished by soldering the package’s tab to a copper plane on the PCB. (Note: The tab on the LME49610’s TO–263 package is electrically connected to VEE.) Through the mechanisms of convection, heat conducts from the LME49610 in all directions. A large percentage moves to the surrounding air, some is absorbed by the circuit board material and some is absorbed by the copper traces connected to the package’s pins. From the PCB material and the copper, it then moves to the air. Natural convection depends on the amount of surface area that contacts the air. If a heat conductive copper plane has perfect thermal conduction (heat spreading) through the plane’s total area, the temperature rise is inversely proportional to the total exposed area. PCB copper planes are, in that sense, an aid to convection. These planes, however, are not thick enough to ensure perfect heat conduction. Therefore, eventually a point of diminishing returns is reached where increasing copper area offers no additional heat conduction to the surrounding air. This is apparent in Figure 6. 2 oz copper boards will have decrease thermal resistance providing a better heat sink compared to 1oz. copper. Beyond 1oz or 2oz copper plane areas, external heatsinks are required. Ultimately, the 1oz copper BANDWITH CONTROL PIN The LME49610’s –3dB bandwidth is approximately 110MHz in the low quiescent-current mode (13mA typical). Select this mode by leaving the BW pin unconnected. Connect the BW pin to the VEE pin to extend the LME49610’s bandwidth to a nominal value of 180MHz. In this mode, the quiescent current increases to approximately 19mA. Bandwidths between these two limits are easily selected by connecting a series resistor between the BW pin and VEE . Regardless of the connection to the LME49610’s BW pin, the rated output current and slew rate remain constant. With the power supply voltage held constant, the wide-bandwidth mode’s increased quiescent current causes a corresponding increase in quiescent power dissipation. For all values of the BW pin voltage, the quiescent power dissipation is equal to the total supply voltage times the quiescent current (IQ * (VCC + |VEE |)). BOOSTING OP AMP OUTPUT CURRENT When placed in the feedback loop, the LME49610 will increase an operational amplifier’s output current. The operational amplifier’s open loop gain will correct any LME49610 errors while operating inside the feedback loop. To ensure that the operational amplifier and buffer system are closed loop stable, the phase shift must be low. For a system gain of one, the LME49610 must contribute less than 20° at the operational amplifier’s unity-gain frequency. Various operating conditions may change or increase the total system phase shift. These phase shift changes may affect the operational amplifier's stability. Unity gain stability is preserved when the LME49610 is placed in the feedback loop of most general-purpose or precision op amps. When the LME46900 is driving high value capacitive loads, the BW pin should be connected to the VEE pin for wide bandwidth and stable operation. The wide bandwidth mode is also suggested for high speed or fast-settling operational amplifiers. This preserves their stability and the ability to faithfully amplify high frequency, fast-changing signals. Stability is ensured when pulsed signals exhibit no oscillations and ringing is minimized while driving the intended load and operating in the worst-case conditions that perturb the LME49610’s phase response. HIGH FREQUENCY APPLICATIONS The LME49610’s wide bandwidth and very high slew rate make it ideal for a variety of high-frequency open-loop applications such as an ADC input driver, 75Ω stepped volume attenuator driver, and other low impedance loads. Circuit board layout and bypassing techniques affect high frequency, fast signal dynamic performance when the LME49610 operates open-loop. www.national.com 12 TA(MAX) = the maximum ambient temperature in the LME49610’s environment PD(MAX) = the maximum recommended power dissipation Note: The allowable thermal resistance is determined by the maximum allowable temperature increase: TRISE = TJ(MAX) - TA(MAX) Thus, if ambient temperature extremes force TRISE to exceed the design maximum, the part must be de-rated by either decreasing PD to a safe level, reducing θJA further, or, if available, using a larger copper area. Procedure 1. First determine the maximum power dissipated by the LME49610, PD(MAX). For the simple case of the buffer driving a resistive load, and assuming equal supplies, PD(MAX) is given by: PDMAX(AC) = (IS x VS) + (VS)2 / (2π2RL) (Watts) (2) 30042562 PDMAX(DC) = (IS x VS) + (VS)2 / RL (Watts) FIGURE 6. Thermal Resistance (typ) for 5 lead TO-263 Package Mounted on 1oz. copper (3) where: VS = |VEE| + VCC (V) IS = quiescent supply current (A) Equation (2) is for sinusoidal output voltages and (3) is for DC output voltages A copper plane may be placed directly beneath the tab. Additionally, a matching plane can be placed on the opposite side. If a plane is placed on the side opposite of the LME49610, connect it to the plane to which the buffer’s metal tab is soldered with a matrix of thermal vias per JEDEC Standard JESD51-5. 2. Determine the maximum allowable die temperature rise, Determining Copper Area Find the required copper heat sink area using the following guidelines: 1. Determine the maximum power dissipation of the LME49610, PD. 2. Specify a maximum operating ambient temperature, TA (MAX). Note that the die temperature, TJ, will be higher than TA by an amount that is dependent on the thermal resistance from junction to ambient, θJA. Therefore, TA must be specified such that TJ does not exceed the absolute maximum die temperature of 150°C. 3. Specify a maximum allowable junction temperature, TJ (MAX), This is the LME49610’s die temperature when the buffer is drawing maximum current (quiescent and load). It is prudent to design for a maximum continuous junction temperature of 100°C to 130°C. Ensure, however, that the junction temperature never exceeds the 150°C absolute maximum rating for the part. 4. Calculate the value of junction to ambient thermal resistance, θJA. TRISE(MAX) = TJ(MAX) - TA(MAX) °C (4) 3. Using the calculated value of TRISE(MAX) and PD(MAX), find the required value of junction to ambient thermal resistance combining equation 1 and equation 4 to derive equation 5: θJA = TRISE(MAX) / PD(MAX) (°C/W) (5) 4. Finally, choose the minimum value of copper area from Figure 6 based on the value for θJA. Example Assume the following conditions: VS = |VEE| + VCC = 30V, RL = 32Ω, IS = 15mA, sinusoidal output voltage, TJ(MAX) = 125° C, TA(MAX) = 85°C. Applying Equation (2): 5. θJA as a function of copper area in square inches is shown in Figure 6. Choose a copper area that will guarantee the specified TJ(MAX) for the calculated θJA. The maximum value of junction to ambient thermal resistance, θJA, is defined as: PDMAX = (IS x VS) + (VS)2 / 2π2RL = (15mA)(30V) + 900V2 / 632Ω = 1.87W θJA = (TJ(MAX) - TA(MAX) ) / PD(MAX) (°C/W) (1) Applying Equation (4): where: TJ(MAX) = the maximum recommended junction temperature TRISE(MAX) = 125°C – 85°C = 40°C 13 www.national.com LME49610 area attains a nominal value of 20°C/W junction to ambient thermal resistance (θJA) under zero air flow. LME49610 SLEW RATE A buffer’s voltage slew rate is its output signal’s rate of change with respect to an input signal’s step changes. For resistive loads, slew rate is limited by internal circuit capacitance and operating current (in general, the higher the operating current for a given internal capacitance, the higher the slew rate). However, when driving capacitive loads, the slew rate may be limited by the available peak output current according to the following expression. Applying Equation (5): θJA = 40°C/1.87W = 21.4°C/W Examining the Copper Area vs. θJA plot (see Figure 6) indicates that a thermal resistance of 21.4°C/W is possible with a 8–10in2 plane of one layer of 1oz copper. Other solutions include using two layers of 1oz copper or the use of 2oz copper. Higher dissipation may require forced air flow. As a safety margin, an extra 15% heat sinking capability is recommended. When amplifying AC signals, wave shapes and the nature of the load (reactive, non-reactive) also influence dissipation. Peak dissipation can be several times the average with reactive loads. It is particularly important to determine dissipation when driving large load capacitance. The LME49610’s dissipation in DC circuit applications is easily computed using Equation (3). After the value of dissipation is determined, the heat sink copper area calculation is the same as for AC signals. www.national.com dv/dt = IPK / CL (6) Output voltages with high slew rates will require large output load currents. For example if the part is required to slew at 1000V/μs with a load capacitance of 1nF, the current demanded from the LME49610 is 1A. Therefore, fast slew rate is incompatible with a capacitive load of this value. Also, if CL is in parallel with the load, the peak current available to the load decreases as CL increases. 14 LME49610 300425a7 FIGURE 7. High Speed Positive and Negative Regulator 15 www.national.com LME49610 Revision History Rev Date 1.0 04/09/08 Initial WEB released. 1.01 10/28/09 Typical and Limit changes on the Short Circuit Output current. www.national.com Description 16 LME49610 Physical Dimensions inches (millimeters) unless otherwise noted Order Number LME49610TS See NS Package TS5B 17 www.national.com LME49610 High Performance, High Fidelity, High Current Audio Buffer Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: 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 Reference www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Solutions 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 Wireless (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. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. Copyright© 2009 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Technical Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Technical Support Center Email: [email protected] National Semiconductor Asia Pacific Technical Support Center Email: [email protected] National Semiconductor Japan Technical Support Center Email: [email protected]