LM4809 Dual 105mW Headphone Amplifier with Active-Low Shutdown Mode General Description Key Specifications The LM4809 is a dual audio power amplifier capable of delivering 105mW per channel of continuous average power into a 16Ω load with 0.1% (THD+N) from a 5V power supply. n THD+N at 1kHz at 105mW continuous average power into 16Ω 0.1% (typ) n THD+N at 1kHz at 70mW continuous average power into 32Ω 0.1% (typ) n Shutdown Current 0.4µA (typ) Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. Since the LM4809 does not require bootstrap capacitors or snubber networks, it is optimally suited for low-power portable systems. The unity-gain stable LM4809 can be configured by external gain-setting resistors. The LM4809 features an externally controlled, active-low, micropower consumption shutdown mode, as well as an internal thermal shutdown protection mechanism. Features n n n n n n Active-low shutdown mode "Click and Pop" reduction circuitry Low shutdown current LLP, MSOP, and SO surface mount packaging No bootstrap capacitors required Unity-gain stable Applications n n n n Headphone Amplifier Personal Computers Microphone Preamplifier PDA’s Typical Application 20009001 *Refer to the Application Information Section for information concerning proper selection of the input and output coupling capacitors. FIGURE 1. Typical Audio Amplifier Application Circuit 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ LM4809 Dual 105mW Headphone Amplifier with Active-Low Shutdown Mode November 2002 LM4809 Connection Diagrams MSOP Package MSOP Marking 20009066 20009002 Top View Order Number LM4809MM See NS Package Number MUA08A SO Package SO Marking 20009067 20009002 Top View Order Number LM4809MA See NS Package Number M08A LLP Package LLP Marking 20009068 20009061 Top View Order Number LM4809LD See NS Package Number LDA08B 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ Thermal Resistance (Note 2) θJA (SO) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage 6.0V Storage Temperature 170˚C/W θJC (SO) 35˚C/W θJA (MSOP) 210˚C/W θJC (MSOP) 56˚C/W −65˚C to +150˚C θJA (LLP) 117˚C/W (Note 9) 3.5kV θJA (LLP) 150˚C/W (Note 10) 250V θJC (LLP) 15˚C/W ESD Susceptibility (Note 4) ESD Machine model (Note 8) Junction Temperature (TJ) 150˚C Soldering Information (Note 1) Operating Ratings Small Outline Package Vapor Phase (60 sec.) 215˚C Infrared (15 sec.) 220˚C Temperature Range TMIN ≤ TA ≤ TMAX −40˚C ≤ T A ≤ 85˚C 2.0V ≤ VCC ≤ 5.5V Supply Voltage (VCC) Note 1: See AN-450 “Surface Mounting and their Effects on Product Reliability” for other methods of soldering surface mount devices. Electrical Characteristics (Notes 2, 3) The following specifications apply for VDD = 5V unless otherwise specified, limits apply to TA = 25˚C. Symbol Parameter Conditions LM4809 Typ (Note 5) Limit (Note 7) Supply Voltage VDD IDD Supply Current VIN = 0V, IO = 0A 1.4 Units (Limits) 2.0 V (min) 5.5 V (max) 3 mA (max) ISD Shutdown Current VIN = 0V, VSHUTDOWN = GND 0.4 2 µA(max) VOS Output Offset Voltage VIN = 0V 4.0 50 mV(max) PO Output Power THD+N = 0.1%, f = 1kHz 65 mW (min) RL = 16Ω 105 RL = 32Ω 70 mW THD+N Total Harmonic Distortion PO = 50mW, RL = 32Ω f = 20Hz to 20kHz 0.3 % Crosstalk Channel Separation RL = 32Ω; PO = 70mW 70 dB PSRR Power Supply Rejection Ratio CB = 1.0µF; VRIPPLE = 200mVPP, f = 1kHz; Input terminated into 50Ω 70 dB VSDIH Shutdown Voltage Input High 0.8 x VDD V (min) VSDIL Shutdown Voltage Input Low 0.2 x VDD V (max) Electrical Characteristics (Notes 2, 3) The following specifications apply for VDD = 3.3V unless otherwise specified, limits apply to TA = 25˚C. Symbol Parameter Conditions LM4809 Typ (Note 5) Limit (Note 7) Units (Limits) IDD Supply Current VIN = 0V, IO = 0A 1.1 ISD Shutdown Current VIN = 0V, VSHUTDOWN = GND 0.4 mA µA VOS Output Offset Voltage VIN = 0V 4.0 mV PO Output Power THD+N = 0.1%, f = 1kHz RL = 16Ω 40 mW RL = 32Ω 28 mW THD+N Total Harmonic Distortion PO = 25mW, RL = 32Ω f = 20Hz to 20kHz 0.4 % Crosstalk Channel Separation RL = 32Ω; PO = 25mW 70 dB 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 3 LM4809 Absolute Maximum Ratings LM4809 Electrical Characteristics (Notes 2, 3) (Continued) The following specifications apply for VDD = 3.3V unless otherwise specified, limits apply to TA = 25˚C. Symbol Parameter Conditions LM4809 Typ (Note 5) CB = 1.0µF; VRIPPLE = 200mVPP, f = 1kHz; Input terminated into 50Ω Limit (Note 7) Units (Limits) 70 dB PSRR Power Supply Rejection Ratio VSDIH Shutdown Voltage Input High 0.8 x VDD V (min) VSDIL Shutdown Voltage Input Low 0.2 x VDD V (max) Electrical Characteristics (Notes 2, 3) The following specifications apply for VDD = 2.6V unless otherwise specified, limits apply to TA = 25˚C. Symbol Parameter Conditions LM4809 Typ (Note 5) IDD Supply Current VIN = 0V, IO = 0A 0.9 Limit (Note 7) Units (Limits) mA ISD Shutdown Current VIN = 0V, VSHUTDOWN = GND 0.2 µA VOS Output Offset Voltage VIN = 0V 4.0 mV PO Output Power THD+N = 0.1%, f = 1kHz RL = 16Ω 20 mW RL = 32Ω 16 mW THD+N Total Harmonic Distortion PO = 15mW, RL = 32Ω f = 20Hz to 20kHz 0.6 % Crosstalk Channel Separation RL = 32Ω; PO = 15mW 70 dB PSRR Power Supply Rejection Ratio CB = 1.0µF; VRIPPLE = 200mVPP, f = 1kHz; Input terminated into 50Ω 70 dB VSDIH Shutdown Voltage Input High 0.8 x VDD V (min) VSDIL Shutdown Voltage Input Low 0.2 x VDD V (max) Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Note 3: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor. Note 5: Typical specifications are specified at +25OC and represent the most likely parametric norm. Note 6: Tested limits are guaranteed to National’s AOQL (Average Outgoing Quality Level). Note 7: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. Note 8: Machine Model ESD test is covered by specification EIAJ IC-121-1981. A 200pF cap is charged to the specified voltage, then discharged directly into the IC with no external series resistor (resistance of discharge path must be under 50Ohms). Note 9: The given θJA is for an LM4809 packaged in an LDA08B wit the Exposed-Dap soldered to a printed circuit board copper pad with an area equivalent to that of the Exposed-Dap itself. Note 10: The given θJA is for an LM4809 packaged in an LDA08B with the Exposed-Dap not soldered to any printed circuit board copper. External Components Description Components (Figure 1) Functional Description 1. Ri The inverting input resistance, along with Rf, set the closed-loop gain. Ri, along with Ci, form a high pass filter with fc = 1/(2πRiCi). 2. Ci The input coupling capacitor blocks DC voltage at the amplifier’s input terminals. Ci, along with Ri, create a highpass filter with fC = 1/(2πRiCi). Refer to the section, Selecting Proper External Components, for an explanation of determining the value of Ci. 3. Rf The feedback resistance, along with Ri, set closed-loop gain. 4. CS This is the supply bypass capacitor. It provides power supply filtering. Refer to the Application Information section for proper placement and selection of the supply bypass capacitor. 5. CB This is the BYPASS pin capacitor. It provides half-supply filtering. Refer to the section, Selecting Proper External Components, for information concerning proper placement and selection of CB. 6. CO This is the output coupling capacitor. It blocks the DC voltage at the amplifier’s output and forms a high pass filter with RL at fO = 1/(2πRLCO) 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ LM4809 Typical Performance Characteristics THD+N vs Frequency THD+N vs Frequency 20009003 20009004 THD+N vs Frequency THD+N vs Frequency 20009005 20009006 THD+N vs Frequency THD+N vs Frequency 20009007 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 20009008 5 LM4809 Typical Performance Characteristics THD+N vs Frequency (Continued) THD+N vs Frequency 20009009 THD+N vs Frequency 20009010 THD+N vs Frequency 20009011 THD+N vs Output Power THD+N vs Output Power 20009013 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 20009012 20009014 (Continued) THD+N vs Output Power THD+N vs Output Power 20009015 20009016 THD+N vs Output Power THD+N vs Output Power 20009017 20009018 THD+N vs Output Power THD+N vs Output Power 20009019 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ LM4809 Typical Performance Characteristics 20009020 7 LM4809 Typical Performance Characteristics (Continued) Output Power vs Load Resistance THD+N vs Output Power 20009022 20009021 Output Power vs Load Resistance Output Power vs Load Resistance 20009023 Output Power vs Supply Voltage Output Power vs Power Supply 20009025 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 20009024 20009026 (Continued) Output Power vs Power Supply Dropout Voltage vs Supply Voltage 20009028 20009027 Power Dissipation vs Output Power Power Dissipation vs Output Power 20009029 20009030 Power Dissipation vs Output Power Channel Separation 20009031 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ LM4809 Typical Performance Characteristics 20009033 9 LM4809 Typical Performance Characteristics Noise Floor (Continued) Power Supply Rejection Ratio 20009034 20009035 Open Loop Frequency Response Open Loop Frequency Response 20009051 20009050 Open Loop Frequency Response Supply Current vs Supply Voltage 20009038 20009044 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ MICRO-POWER SHUTDOWN The voltage applied to the SHUTDOWN pin controls the LM4809’s shutdown function. Activate micro-power shutdown by applying a logic low voltage to the SHUTDOWN pin. The logic threshold is typically VDD/2. When active, the LM4809’s micro-power shutdown feature turns off the amplifier’s bias circuitry, reducing the supply current. The low 0.4µA typical shutdown current is achieved by applying a voltage that is as near as GND as possible to the SHUTDOWN pin. A voltage that is above GND may increase the shutdown current. There are a few ways to control the micro-power shutdown. These include using a single-pole, single-throw switch, a microprocessor, or a microcontroller. When using a switch, connect an external 100kΩ pull-down resistor between the SHUTDOWN pin and GND. Connect the switch between the SHUTDOWN pin and VDD. Select normal amplifier operation by closing the switch. Opening the switch connects the SHUTDOWN pin to GND through the pull-down resistor, activating micro-power shutdown. The switch and resistor guarantee that the SHUTDOWN pin will not float. This prevents unwanted state changes. In a system with a microprocessor or a microcontroller, use a digital output to apply the control voltage to the SHUTDOWN pin. Driving the SHUTDOWN pin with active circuitry eliminates the pull-down resistor. PDMAX = (TJMAX − TA) / θJA For package MUA08A, θJA = 210˚C/W. TJMAX = 150˚C for the LM4809. Depending on the ambient temperature, TA, of the system surroundings, Equation 2 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 1 is greater than that of Equation 2, then either the supply voltage must be decreased, the load impedance increased or TA reduced. For the typical application of a 5V power supply, with a 32Ω load, the maximum ambient temperature possible without violating the maximum junction temperature is approximately 133.2˚C provided that device operation is around the maximum power dissipation point. Power dissipation is a function of output power and thus, if typical operation is not around the maximum power dissipation point, the ambient temperature may be increased accordingly. Refer to the Typical Performance Characteristics curves for power dissipation information for lower output powers. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. Applications that employ a 5V regulator typically use a 10µF in parallel with a 0.1µF filter capacitors to stabilize the regulator’s output, reduce noise on the supply line, and improve the supply’s transient response. However, their presence does not eliminate the need for a local 1.0µF tantalum bypass capacitance connected between the LM4809’s supply pins and ground. Keep the length of leads and traces that connect capacitors between the LM4809’s power supply pin and ground as short as possible. Connecting a 4.7µF capacitor, CB, between the BYPASS pin and ground improves the internal bias voltage’s stability and improves the amplifier’s PSRR. The PSRR improvements increase as the bypass pin capacitor value increases. Too large, however, increases the amplifier’s turn-on time. The selection of bypass capacitor values, especially CB, depends on desired PSRR requirements, click and pop performance (as explained in the section, Selecting Proper External Components), system cost, and size constraints. EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATION The LM4809’s exposed-Dap (die attach paddle) package (LD) provides a low thermal resistance between the die and the PCB to which the part is mounted and soldered. This allows rapid heat transfer from the die to the surrounding PCB copper traces, ground plane, and surrounding air. The LD package should have its DAP soldered to a copper pad on the PCB. The DAP’s PCB copper pad may be connected to a large plane of continuous unbroken copper. This plane forms a thermal mass, heat sink, and radiation area. However, since the LM4809 is designed for headphone applications, connecting a copper plane to the DAP’s PCB copper pad is not required. The LM4809’s Power Dissipation vs Output Power Curve in the Typical Performance Characteristics shows that the maximum power dissipated is just 45mW per amplifier with a 5V power supply and a 32Ω load. Further detailed and specific information concerning PCB layout, fabrication, and mounting an LD (LLP) package is available from National Semiconductor’s Package Engineering Group under application note AN1187. SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4809’s performance requires properly selecting external components. Though the LM4809 operates well when using external components with wide tolerances, best performance is achieved by optimizing component values. The LM4809 is unity-gain stable, giving a designer maximum design flexibility. The gain should be set to no more than a given application requires. This allows the amplifier to achieve minimum THD+N and maximum signal-to-noise ratio. These parameters are compromised as the closed-loop gain increases. However, low gain demands input signals with greater voltage swings to achieve maximum output power. Fortunately, many signal sources such as audio POWER DISSIPATION Power dissipation is a major concern when using any power amplifier and must be thoroughly understood to ensure a successful design. Equation 1 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (VDD) 2 / (2π2RL) (1) Since the LM4809 has two operational amplifiers in one package, the maximum internal power dissipation point is twice that of the number which results from Equation 1. Even with the large internal power dissipation, the LM4809 does 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ (2) 11 LM4809 not require heat sinking over a large range of ambient temperature. From Equation 1, assuming a 5V power supply and a 32Ω load, the maximum power dissipation point is 40mW per amplifier. Thus the maximum package dissipation point is 80mW. The maximum power dissipation point obtained must not be greater than the power dissipation that results from Equation 2: Application Information LM4809 Application Information (Continued) CODECs have outputs of 1VRMS (2.83VP-P). Please refer to the Audio Power Amplifier Design section for more information on selecting the proper gain. Input and Output Capacitor Value Selection Amplifying the lowest audio frequencies requires high value input and output coupling capacitors (CI and CO in Figure 1). A high value capacitor can be expensive and may compromise space efficiency in portable designs. In many cases, however, the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150Hz. Applications using speakers with this limited frequency response reap little improvement by using high value input and output capacitors. Besides affecting system cost and size, Ci has an effect on the LM4809’s click and pop performance. The magnitude of the pop is directly proportional to the input capacitor’s size. Thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired −3dB frequency. Please refer to the Optimizing Click and Pop Reduction Performance section for a more detailed discussion on click and pop performance. As shown in Figure 1, the input resistor, RI and the input capacitor, CI, produce a −3dB high pass filter cutoff frequency that is found using Equation (3). In addition, the output load RL, and the output capacitor CO, produce a -3db high pass filter cutoff frequency defined by Equation (4). fI-3db =1/2πRICI fO-3db =1/2πRLCO the BYPASS pin is stable, the device becomes fully operational. During device turn-on, a transient (pop) is created from a voltage difference between the input and output of the amplifier as the voltage on the BYPASS pin reaches 1/2 VDD. For this discussion, the input of the amplifier refers to the node between RI and CI. Ideally, the input and output track the voltage applied to the BYPASS pin. During turn-on, the buffer-configured amplifier output charges the input capacitor, CI, through the input resistor, RI. This input resistor delays the charging time of CI thereby causing the voltage difference between the input and output that results in a transient (pop). Higher value capacitors need more time to reach a quiescent DC voltage (usually 1/2 VDD) when charged with a fixed current. Decreasing the value of CI and RI will minimize turn-on pops at the expense of the desired -3dB frequency. Although the BYPASS pin current cannot be modified, changing the size of CB alters the device’s turn-on time and the magnitude of “clicks and pops”. Increasing the value of CB reduces the magnitude of turn-on pops. However, this presents a tradeoff: as the size of CB increases, the turn-on time increases. There is a linear relationship between the size of CB and the turn-on time. Here are some typical turn-on times for various values of CB: (3) (4) Also, careful consideration must be taken in selecting a certain type of capacitor to be used in the system. Different types of capacitors (tantalum, electrolytic, ceramic) have unique performance characteristics and may affect overall system performance. CB TON 0.1µF 80ms 0.22µF 170ms 0.33µF 270ms 0.47µF 370ms 0.68µF 490ms 1.0µF 920ms 2.2µF 1.8sec 3.3µF 2.8sec 4.7µF 3.4sec 10µF 7.7sec Bypass Capacitor Value Selection Besides minimizing the input capacitor size, careful consideration should be paid to the value of CB, the capacitor connected to the BYPASS pin. Since CB determines how fast the LM4809 settles to quiescent operation, its value is critical when minimizing turn-on pops. The slower the LM4809’s outputs ramp to their quiescent DC voltage (nominally 1/2 VDD), the smaller the turn-on pop. Choosing CB equal to 4.7µF along with a small value of Ci (in the range of 0.1µF to 0.47µF), produces a click-less and pop-less shutdown function. As discussed above, choosing Ci no larger than necessary for the desired bandwith helps minimize clicks and pops. In order eliminate “clicks and pops”, all capacitors must be discharged before turn-on. Rapidly switching VDD may not allow the capacitors to fully discharge, which may cause “clicks and pops”. In a single-ended configuration, the output is coupled to the load by CO. This capacitor usually has a high value. CO discharges through internal 20kΩ resistors. Depending on the size of CO, the discharge time constant can be relatively large. To reduce transients in single-ended mode, an external 1kΩ–5kΩ resistor can be placed in parallel with the internal 20kΩ resistor. The tradeoff for using this resistor is increased quiescent current. OPTIMIZING CLICK AND POP REDUCTION PERFORMANCE The LM4809 contains circuitry that minimizes turn-on and shutdown transients or “clicks and pop”. For this discussion, turn-on refers to either applying the power supply voltage or when the shutdown mode is deactivated. During turn-on, the LM4809’s internal amplifiers are configured as unity gain buffers. An internal current source charges up the capacitor on the BYPASS pin in a controlled, linear manner. The gain of the internal amplifiers remains unity until the voltage on the BYPASS pin reaches 1/2 VDD . As soon as the voltage on Design a Dual 70mW/32Ω Audio Amplifier 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ AUDIO POWER AMPLIFIER DESIGN Given: Power Output Load Impedance Input Level Input Impedance 70 mW 32Ω 1 Vrms (max) 20kΩ Bandwidth 100 Hz–20 kHz ± 0.50dB The design begins by specifying the minimum supply voltage necessary to obtain the specified output power. One way to (Continued) AV = Rf/Ri find the minimum supply voltage is to use the Output Power vs Supply Voltage curve in the Typical Performance Characteristics section. Another way, using Equation (5), is to calculate the peak output voltage necessary to achieve the desired output power for a given load impedance. To account for the amplifier’s dropout voltage, two additional voltages, based on the Dropout Voltage vs Supply Voltage in the Typical Performance Characteristics curves, must be added to the result obtained by Equation (5). For a single-ended application, the result is Equation (6). (8) The value of Rf is 30kΩ. The last step in this design is setting the amplifier’s −3db frequency bandwidth. To achieve the desired ± 0.25dB pass band magnitude variation limit, the low frequency response must extend to at lease one−fifth the lower bandwidth limit and the high frequency response must extend to at least five times the upper bandwidth limit. The gain variation for both response limits is 0.17dB, well within the ± 0.25dB desired limit. The results are an fL = 100Hz/5 = 20Hz (9) fH = 20kHz*5 = 100kHz (10) (5) and a VDD ≥ (2VOPEAK + (VODTOP + VODBOT)) (6) The Output Power vs Supply Voltage graph for a 32Ω load indicates a minimum supply voltage of 4.8V. This is easily met by the commonly used 5V supply voltage. The additional voltage creates the benefit of headroom, allowing the LM4809 to produce peak output power in excess of 70mW without clipping or other audible distortion. The choice of supply voltage must also not create a situation that violates maximum power dissipation as explained above in the Power Dissipation section. Remember that the maximum power dissipation point from Equation (1) must be multiplied by two since there are two independent amplifiers inside the package. Once the power dissipation equations have been addressed, the required gain can be determined from Equation (7). As stated in the External Components section, both Ri in conjunction with Ci, and Co with RL, create first order highpass filters. Thus to obtain the desired low frequency response of 100Hz within ± 0.5dB, both poles must be taken into consideration. The combination of two single order filters at the same frequency forms a second order response. This results in a signal which is down 0.34dB at five times away from the single order filter −3dB point. Thus, a frequency of 20Hz is used in the following equations to ensure that the response is better than 0.5dB down at 100Hz. Ci ≥ 1 / (2π * 20kΩ * 20Hz) = 0.397µF; use 0.39µF.(11) Co ≥ 1 / (2π * 32Ω * 20Hz) = 249µF; use 330µF. (12) (7) The high frequency pole is determined by the product of the desired high frequency pole, fH, and the closed-loop gain, AV. With a closed-loop gain of 1.5 and fH = 100kHz, the resulting GBWP = 150kHz which is much smaller than the LM4809’s GBWP of 900kHz. This figure displays that if a designer has a need to design an amplifier with a higher gain, the LM4809 can still be used without running into bandwidth limitations. Thus, a minimum gain of 1.497 allows the LM4809 to reach full output swing and maintain low noise and THD+N perfromance. For this example, let AV =1.5. The amplifiers overall gain is set using the input (Ri ) and feedback (Rf ) resistors. With the desired input impedance set at 20kΩ, the feedback resistor is found using Equation (8). 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 13 LM4809 Application Information LM4809 Demonstration Board Schematic 20009057 FIGURE 2. LM4809 Demonstration Board Schematic 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ LM4809 Demonstration Board Layout 20009058 FIGURE 3. Recommended MSOP PC Board Layout Component-Side Silkscreen 20009059 FIGURE 4. Recommended MSOP PC Board Layout Component-Side Layout 20009060 FIGURE 5. Recommended MSOP PC Board Layout Bottom-Side Layout 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 15 LM4809 Demonstration Board Layout (Continued) 20009062 FIGURE 6. Recommended LD PC Board Layout Component-Side Silkscreen 20009063 FIGURE 7. Recommended LD PC Board Layout Component-Side Layout 20009064 FIGURE 8. Recommended LD PC Board Layout Bottom-Side Layout 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ inches (millimeters) unless otherwise noted Order Number LM4809MM NS Package Number MUA08A Order Number LM4809MA NS Package Number M08A 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 17 LM4809 Physical Dimensions LM4809 Dual 105mW Headphone Amplifier with Active-Low Shutdown Mode Physical Dimensions inches (millimeters) unless otherwise noted (Continued) Order Number LM4809LD NS Package Number LDA08B LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems 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. 深圳市森利威尔电子有限公司 李生：１３５ １０２９ ４４０６ 2. A critical component is any component of 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.