LM4838 Stereo 2W Audio Power Amplifiers with DC Volume Control and Selectable Gain General Description Key Specifications The LM4838 is a monolithic integrated circuit that provides DC volume control, and stereo bridged audio power amplifiers capable of producing 2W into 4Ω (Note 1) with less than 1.0% THD or 2.2W into 3Ω (Note 2) with less than 1.0% THD. Boomer ® audio integrated circuits were designed specifically to provide high quality audio while requiring a minimum amount of external components. The LM4838 incorporates a DC volume control, stereo bridged audio power amplifiers and a selectable gain or bass boost, making it optimally suited for multimedia monitors, portable radios, desktop, and portable computer applications. The LM4838 features an externally controlled, low-power consumption shutdown mode, and both a power amplifier and headphone mute for maximum system flexibility and performance. n PO at 1% THD+N n into 3Ω (LQ & MTE) n into 4Ω (LQ & MTE) n into 8Ω (MT, MTE, ITL, & LQ) n Single-ended mode - THD+N at 85mW into 32Ω n Shutdown current Note 1: When properly mounted to the circuit board, the LM4838LQ and LM4838MTE will deliver 2W into 4Ω. The LM4838MT and LM4838ITL will deliver 1.1W into 8Ω. See Application Information section Exposed-DAP package PCB Mounting Considerations for more information. Note 2: An LM4838LQ and LM4838MTE that have been properly mounted to the circuit board and forced-air cooled will deliver 2.2W into 3Ω. 2.2W (typ) 2.0W (typ) 1.1W (typ) 1.0%(typ) 0.7µA (typ) Features n n n n n n DC Volume Control Interface System Beep Detect Stereo switchable bridged/single-ended power amplifiers Selectable internal/external gain and bass boost “Click and pop” suppression circuitry Thermal shutdown protection circuitry Applications n Portable and Desktop Computers n Multimedia Monitors n Portable Radios, PDAs, and Portable TVs Block Diagram 20013301 FIGURE 1. LM4838 Block Diagram Boomer ® is a registered trademark of NationalSemiconductor Corporation. © 2003 National Semiconductor Corporation DS200133 www.national.com LM4838 Stereo 2W Audio Power Amplifiers with DC Volume Control and Selectable Gain January 2003 LM4838 Connection Diagrams LLP Package 20013335 Top View Order Number LM4838LQ See NS Package Number LQA028AA for Exposed-DAP LLP TSSOP Package 20013302 Top View Order Number LM4838MT See NS Package Number MTC28 for TSSOP Order Number LM4838MTE See NS Package Number MXA28A for Exposed-DAP TSSOP www.national.com 2 LM4838 Connection Diagrams (Continued) 36 Bump micro SMD 20013388 Top View Order Number LM4838ITL, LM4838ITLX See NS Package Number TLA36AAA micro SMD Marking 20013387 Top View X - Date Code T - Die Traceability G - Boomer Family A4 - LM4838ITL 6 NC Right Out - VDD Right Out + GND NC 5 GND Right Gain 2 Right Gain 1 Gain Select Shutdown Mode 4 Bypass NC NC DC Vol Mute VDD 3 HP Sense NC NC Beep In Right Dock GND 2 GND Left Gain 2 Left Gain 1 Left In Left Dock Right In 1 NC Left Out - VDD Left Out + GND NC Pin Designator A B C D E F 3 www.national.com LM4838 Absolute Maximum Ratings (Note 10) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage -65˚C to +150˚C −0.3V to VDD +0.3V Input Voltage Power Dissipation (Note 11) Internally limited ESD Susceptibility (Note 12) 2000V ESD Susceptibility (Note 13) 200V Junction Temperature 20˚C/W θJA (typ) — MTC28 80˚C/W θJC (typ) — MXA28A 6.0V Storage Temperature θJC (typ) — MTC28 150˚C 2˚C/W θJA (typ) — MXA28A (exposed DAP) (Note 4) 41˚C/W θJA (typ) — MXA28A (exposed DAP) (Note 3) 54˚C/W θJA (typ) — MXA28A (exposed DAP) (Note 5) 59˚C/W θJA (typ) — MXA28A (exposed DAP) (Note 6) 93˚C/W θJA (typ) — ITL36AAA Soldering Information Small Outline Package Vapor Phase (60 sec.) 215˚C Infrared (15 sec.) 220˚C 100˚C/W θJC (typ) — ITL36AAA (Note 16) Operating Ratings See AN-450 “Surface Mounting and their Effects on Product Reliability” for other methods of soldering surface mount devices. θJC (typ) — LQA028AA 3˚C/W θJA (typ) — LQA028AA 42˚C/W 65˚C/W Temperature Range TMIN ≤ TA ≤TMAX −40˚C ≤TA ≤ 85˚C Supply Voltage 2.7V≤ VDD ≤ 5.5V Electrical Characteristics for Entire IC (Notes 7, 10) The following specifications apply for VDD = 5V unless otherwise noted. Limits apply for TA = 25˚C. LM4838 Symbol VDD Parameter Conditions Typical (Note 14) Limit (Note 15) Supply Voltage Units (Limits) 2.7 V (min) 5.5 V (max) mA (max) IDD Quiescent Power Supply Current VIN = 0V, IO = 0A 15 30 ISD Shutdown Current Vshutdown = VDD 0.7 2.0 VIH Headphone Sense High Input Voltage 4 V (min) VIL Headphone Sense Low Input Voltage 0.8 V (max) µA (max) Electrical Characteristics for Volume Attenuators (Notes 7, 10) The following specifications apply for VDD = 5V. Limits apply for TA = 25˚C. LM4838 Symbol CRANGE Parameter Attenuator Range Conditions Typical (Note 14) Limit (Note 15) Gain with VDCVol = 5V, No Load Attenuation with VDCVol = 0V (BM & SE) AM Mute Attenuation Units (Limits) ± 0.75 dB (max) -75 dB (min) Vmute = 5V, Bridged Mode (BM) -78 dB (min) Vmute = 5V, Single-Ended Mode (SE) -78 dB (min) Electrical Characteristics for Single-Ended Mode Operation (Notes 7, 10) The following specifications apply for VDD = 5V. Limits apply for TA = 25˚C. LM4838 Symbol PO Parameter Output Power www.national.com Conditions Typical (Note 14) Limit (Note 15) Units (Limits) THD = 1.0%; f = 1kHz; RL = 32Ω 85 mW THD = 10%; f = 1 kHz; RL = 32Ω 95 mW 4 LM4838 Electrical Characteristics for Single-Ended Mode Operation (Notes 7, 10) (Continued) The following specifications apply for VDD = 5V. Limits apply for TA = 25˚C. LM4838 Symbol Parameter Units (Limits) Conditions Typical (Note 14) 0.065 % Limit (Note 15) THD+N Total Harmonic Distortion+Noise VOUT = 1VRMS, f=1kHz, RL = 10kΩ, AVD = 1 PSRR Power Supply Rejection Ratio CB = 1.0 µF, f =120 Hz, VRIPPLE = 200 mVrms 58 dB SNR Signal to Noise Ratio POUT =75 mW, R Filter 102 dB Xtalk Channel Separation f=1kHz, CB = 1.0 µF 65 dB L = 32Ω, A-Wtd Electrical Characteristics for Bridged Mode Operation (Notes 7, 10) The following specifications apply for VDD = 5V, unless otherwise noted. Limits apply for TA = 25˚C. LM4838 Symbol Parameter Conditions Typical (Note 14) Limit (Note 15) 5 ± 50 Units (Limits) VOS Output Offset Voltage VIN = 0V, No Load PO Output Power THD + N = 1.0%; f=1kHz; RL = 3Ω (Note 8) 2.2 W THD + N = 1.0%; f=1kHz; RL = 4Ω (Note 9) 2 W THD = 1% (max);f = 1 kHz; RL = 8Ω 1.1 mV (max) 1.0 W (min) THD+N = 10%;f = 1 kHz; RL = 8Ω 1.5 W THD+N Total Harmonic Distortion+Noise PO = 1W, 20 Hz < f < 20 kHz, RL = 8Ω, AVD = 2 0.3 % PO = 340 mW, RL = 32Ω 1.0 % PSRR Power Supply Rejection Ratio CB = 1.0 µF, f = 120 Hz, VRIPPLE = 200 mVrms; RL = 8Ω 74 dB SNR Signal to Noise Ratio VDD = 5V, POUT = 1.1W, RL = 8Ω, A-Wtd Filter 93 dB Xtalk Channel Separation f=1kHz, CB = 1.0 µF 70 dB Note 3: The θJA given is for an MXA28A package whose exposed-DAP is soldered to an exposed 2in 2 piece of 1 ounce printed circuit board copper. Note 4: The θJA given is for an MXA28A package whose exposed-DAP is soldered to a 2in2 piece of 1 ounce printed circuit board copper on a bottom side layer through 21 8mil vias. Note 5: The θJA given is for an MXA28A package whose exposed-DAP is soldered to an exposed 1in 2 piece of 1 ounce printed circuit board copper. Note 6: The θJA given is for an MXA28A package whose exposed-DAP is not soldered to any copper. Note 7: All voltages are measured with respect to the ground pins, unless otherwise specified. All specifications are tested using the typical application as shown in Figure 1. Note 8: When driving 3Ω loads from a 5V supply the LM4838LQ, LM4838ITL and LM4838MTE must be mounted to the circuit board and forced-air cooled. Note 9: When driving 4Ω loads from a 5V supply the LM4838LQ, LM4838ITL and LM4838MTE must be mounted to the circuit board. Note 10: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance. Note 11: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θ JA, and the ambient temperature TA. The maximum allowable power dissipation is PDMAX = (TJMAX − TA )/θJA. For the LM4838, TJMAX = 150˚C, and the typical junction-to-ambient thermal resistance for each package can be found in the Absolute Maximum Ratings section above. Note 12: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Note 13: Machine Model, 220 pF–240 pF discharged through all pins. Note 14: Typicals are measured at 25˚C and represent the parametric norm. Note 15: Limits are guaranteed to National’s AOQL ( Average Outgoing Quality Level). Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. 5 www.national.com LM4838 Electrical Characteristics for Bridged Mode Operation (Notes 7, 10) (Continued) Note 16: All bumps have the same thermal resistance and contribute equally when used to lower thermal resistance. The LM4838ITL demo board (views featured in the Application Information section) is a four layer board with two inner layers. The second inner layer is a VDD plane with the bottom outside layer a GND plane. The planes measure 1,900mils x 1,750mils (48.26mm x 44.45mm) and aid in spreading heat due to power dissipation within the IC. Typical Application 20013303 FIGURE 2. Typical Application Circuit ( LQ Package Pinout ) Truth Table for Logic Inputs (Note 17) Gain Sel Mode Headphone Sense Mute Shutdown Output Stage Set To DC Volume Output Stage Configuration 0 0 0 0 0 0 0 1 0 0 Internal Gain Fixed BTL Internal Gain Fixed 0 1 0 0 0 SE Internal Gain Adjustable BTL 0 1 1 0 1 0 0 0 0 Internal Gain Adjustable SE 0 External Gain Fixed BTL 1 0 1 0 0 External Gain Fixed SE 1 1 1 1 0 0 0 External Gain Adjustable BTL 1 0 0 External Gain Adjustable X SE X X 1 0 Muted X Muted X X X X 1 Shutdown X X Note 17: If system beep is detected on the Beep In pin, the system beep will be passed through the bridged amplifier regardless of the logic of the Mute and HP sense pins. www.national.com 6 LM4838 Typical Performance Characteristics MTE Specific Characteristics LM4838MTE THD+N vs Output Power LM4838MTE THD+N vs Frequency 20013371 20013370 LM4838MTE THD+N vs Output Power LM4838MTE THD+N vs Frequency 20013372 20013373 LM4838MTE Power Dissipation vs Output Power LM4838MTE (Note 18) Power Derating Curve 20013365 20013364 Note 18: These curves show the thermal dissipation ability of the LM4838MTE at different ambient temperatures given these conditions: 500LFPM + 2in2: The part is soldered to a 2in2, 1 oz. copper plane with 500 linear feet per minute of forced-air flow across it. 2in2on bottom: The part is soldered to a 2in2, 1oz. copper plane that is on the bottom side of the PC board through 21 8 mil vias. 2in2: The part is soldered to a 2in2, 1oz. copper plane. 1in2: The part is soldered to a 1in2, 1oz. copper plane. Not Attached: The part is not soldered down and is not forced-air cooled. 7 www.national.com LM4838 Non-MTE Specific Characteristics THD+N vs Frequency THD+N vs Frequency 20013358 20013357 THD+N vs Frequency THD+N vs Frequency 20013314 20013315 THD+N vs Frequency THD+N vs Frequency 20013317 20013316 www.national.com 8 LM4838 Non-MTE Specific Characteristics (Continued) THD+N vs Frequency THD+N vs Frequency 20013318 20013319 THD+N vs Frequency THD+N vs Frequency 20013321 20013320 THD+N vs Frequency THD+N vs Output Power 20013324 20013322 9 www.national.com LM4838 Non-MTE Specific Characteristics (Continued) THD+N vs Output Power THD+N vs Output Power 20013325 20013326 THD+N vs Output Power THD+N vs Output Power 20013327 20013328 THD+N vs Output Power THD+N vs Output Power 20013330 20013329 www.national.com 10 LM4838 Non-MTE Specific Characteristics (Continued) THD+N vs Output Power THD+N vs Output Power 20013331 20013332 THD+N vs Output Power THD+N vs Output Power 20013334 20013333 THD+N vs Output Voltage Docking Station Pins THD+N vs Output Voltage Docking Station Pins 20013360 20013359 11 www.national.com LM4838 Typical Performance Characteristics Output Power vs Load Resistance Dropout Voltage 20013362 20013353 Output Power vs Load Resistance Output Power vs Load Resistance 20013306 20013307 Power Supply Rejection Ratio Output Power vs Load Resistance 20013339 20013308 www.national.com 12 LM4838 Typical Performance Characteristics (Continued) Noise Floor Noise Floor 20013342 20013341 Volume Control Characteristics External Gain/ Bass Boost Characteristics 20013340 20013361 Power Dissipation vs Output Power Power Dissipation vs Output Power 20013351 20013352 13 www.national.com LM4838 Typical Performance Characteristics (Continued) Power Derating Curve Crosstalk 20013363 20013349 Output Power vs Supply voltage Output Power vs Supply Voltage 20013354 20013356 Supply Current vs Supply Voltage LM4838ITL (Note 19) Power Derating Curve 20013394 20013309 Note 19: These curves show the thermal dissipation of the LM4838ITL at different ambient temperatures with a thermal plane of size shown on an outside PCB layer using 1oz. copper. www.national.com 14 EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATIONS The LM4838’s exposed-DAP (die attach paddle) packages (MTE, LQ) provide 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, finally, surrounding air. The result is a low voltage audio power amplifier that produces 2.1W at ≤ 1% THD with a 4Ω load. This high power is achieved through careful consideration of necessary thermal design. Failing to optimize thermal design may compromise the LM4838’s high power performance and activate unwanted, though necessary, thermal shutdown protection. The MTE and LQ packages must have their exposed DAPs soldered to a grounded copper pad on the PCB. The DAP’s PCB copper pad is connected to a large grounded plane of continuous unbroken copper. This plane forms a thermal mass heat sink and radiation area. Place the heat sink area on either outside plane in the case of a two-sided PCB, or on an inner layer of a board with more than two layers. Connect the DAP copper pad to the inner layer or backside copper heat sink area with 32(4x8) (MTE) or 6(3x2) (LQ) vias. The via diameter should be 0.012in–0.013in with a 1.27mm pitch. Ensure efficient thermal conductivity by platingthrough and solder-filling the vias. Best thermal performance is achieved with the largest practical copper heat sink area. If the heatsink and amplifier share the same PCB layer, a nominal 2.5in2 (min) area is necessary for 5V operation with a 4Ω load. Heatsink areas not placed on the same PCB layer as the LM4838 MTE and LQ packages should be 5in2 (min) for the same supply voltage and load resistance. The last two area recommendations apply for 25˚C ambient temperature. Increase the area to compensate for ambient temperatures above 25˚C. In systems using cooling fans, the LM4838MTE can take advantage of forced air cooling. With an air flow rate of 450 linear-feet per minute and a 2.5in2 exposed copper or 5.0in2 inner layer copper plane heatsink, the LM4838MTE can continuously drive a 3Ω load to full power. The LM4838LQ achieves the same output power level without forced air cooling. In all circumstances and conditions, the junction temperature must be held below 150˚C to prevent activating the LM4838’s thermal shutdown protection. The LM4838’s power de-rating curve in the Typical Performance Characteristics shows the maximum power dissipation versus temperature. Example PCB layouts for the exposed-DAP TSSOP and LQ packages are shown in the Demonstration Board Layout section. Further detailed and specific information concerning PCB layout, fabrication, and mounting an LQ (LLP) package is available in National Semiconductor’s AN1187. The micro SMD package (LM4838ITL) thermals work in a similar way to the LQ and MTE packages in that a thermal plane increases the heat transfer from the die. The thermal plane can be any electrical potential but needs to be below the package to aid in the spreading the heat from the die out to surrounding PCB areas to reduce the thermal resistance of the micro SMD package. The thermal plane is most effective when placed on the top or first internal PCB layers. The traces connecting the bumps also contribute to spreading heat away from the die. The same recommendations for the size of the thermal plane as given above apply for the ITL package, namely 2.5in2 minimum for top layer thermal plane and 5in2 minimum for internal or bottom layers. BRIDGE CONFIGURATION EXPLANATION As shown in Figure 2, the LM4838 output stage consists of two pairs of operational amplifiers, forming a two-channel (channel A and channel B) stereo amplifier. (Though the following discusses channel A, it applies equally to channel B.) Figure 2 shows that the first amplifier’s negative (-) output serves as the second amplifier’s input. This results in both amplifiers producing signals identical in magnitude, but 180˚ out of phase. Taking advantage of this phase difference, a load is placed between −OUTA and +OUTA and driven differentially (commonly referred to as “bridge mode”). This results in a differential gain of AVD = 2 * (Rf/R i) (1) Bridge mode amplifiers are different from single-ended amplifiers that drive loads connected between a single amplifier’s output and ground. For a given supply voltage, bridge mode has a distinct advantage over the single-ended configuration: its differential output doubles the voltage swing across the load. This produces four times the output power when compared to a single-ended amplifier under the same conditions. This increase in attainable output power assumes that the amplifier is not current limited or that the output signal is not clipped. To ensure minimum output signal clipping when choosing an amplifier’s closed-loop gain, refer to the Audio Power Amplifier Design section. Another advantage of the differential bridge output is no net DC voltage across the load. This is accomplished by biasing channel A’s and channel B’s outputs at half-supply. This eliminates the coupling capacitor that single supply, singleended amplifiers require. Eliminating an output coupling capacitor in a single-ended configuration forces a single-supply amplifier’s half-supply bias voltage across the load. This increases internal IC power dissipation and may permanently damage loads such as speakers. 15 www.national.com LM4838 PCB LAYOUT AND SUPPLY REGULATION CONSIDERATIONS FOR DRIVING 3Ω AND 4Ω LOADS Power dissipated by a load is a function of the voltage swing across the load and the load’s impedance. As load impedance decreases, load dissipation becomes increasingly dependent on the interconnect (PCB trace and wire) resistance between the amplifier output pins and the load’s connections. Residual trace resistance causes a voltage drop, which results in power dissipated in the trace and not in the load as desired. For example, 0.1Ω trace resistance reduces the output power dissipated by a 4Ω load from 2.1W to 2.0W. This problem of decreased load dissipation is exacerbated as load impedance decreases. Therefore, to maintain the highest load dissipation and widest output voltage swing, PCB traces that connect the output pins to a load must be as wide as possible. Poor power supply regulation adversely affects maximum output power. A poorly regulated supply’s output voltage decreases with increasing load current. Reduced supply voltage causes decreased headroom, output signal clipping, and reduced output power. Even with tightly regulated supplies, trace resistance creates the same effects as poor supply regulation. Therefore, making the power supply traces as wide as possible helps maintain full output voltage swing. Application Information LM4838 Application Information The above examples assume that a device is a surface mount part operating around the maximum power dissipation point. Since internal power dissipation is a function of output power, higher ambient temperatures are allowed as output power or duty cycle decreases. If the result of Equation (2) is greater than that of Equation (3), then decrease the supply voltage, increase the load impedance, or reduce the ambient temperature. If these measures are insufficient, a heat sink can be added to reduce θJA. The heat sink can be created using additional copper area around the package, with connections to the ground pin(s), supply pin and amplifier output pins. External, solder attached SMT heatsinks such as the Thermalloy 7106D can also improve power dissipation. When adding a heat sink, the θJA is the sum of θJC, θCS, and θSA. (θJC is the junction-to-case thermal impedance, θCS is the case-to-sink thermal impedance, and θSA is the sink-to-ambient thermal impedance.) Refer to the Typical Performance Characteristics curves for power dissipation information at lower output power levels. (Continued) POWER DISSIPATION Power dissipation is a major concern when successful single-ended or bridged amplifier. states the maximum power dissipation point ended amplifier operating at a given supply driving a specified output load. PDMAX = (VDD)2/(2π2RL) designing a Equation (2) for a singlevoltage and Single-Ended (2) However, a direct consequence of the increased power delivered to the load by a bridge amplifier is higher internal power dissipation for the same conditions. The LM4838 has two operational amplifiers per channel. The maximum internal power dissipation per channel operating in the bridge mode is four times that of a single-ended amplifier. From Equation (3), assuming a 5V power supply and a 4Ω load, the maximum single channel power dissipation is 1.27W or 2.54W for stereo operation. POWER SUPPLY BYPASSING PDMAX = 4 * (VDD)2/(2π2RL) Bridge Mode 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 10 µF in parallel with a 0.1 µF filter capacitor 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 LM4838’s supply pins and ground. Do not substitute a ceramic capacitor for the tantalum. Doing so may cause oscillation. Keep the length of leads and traces that connect capacitors between the LM4838’s power supply pin and ground as short as possible. Connecting a 1µF capacitor, CB, between the BYPASS pin and ground improves the internal bias voltage’s stability and the amplifier’s PSRR. The PSRR improvements increase as the BYPASS pin capacitor value increases. Too large a capacitor, however, increases turn-on time and can compromise the amplifier’s click and pop performance. The selection of bypass capacitor values, especially CB, depends on desired PSRR requirements, click and pop performance (as explained in the following section, Selecting Proper External Components), system cost, and size constraints. (3) The LM4838’s power dissipation is twice that given by Equation (2) or Equation (3) when operating in the single-ended mode or bridge mode, respectively. Twice the maximum power dissipation point given by Equation (3) must not exceed the power dissipation given by Equation (4): PDMAX' = (TJMAX − TA)/θJA (4) The LM4838’s TJMAX = 150˚C. In the LQ package soldered to a DAP pad that expands to a copper area of 5in2 on a PCB, the LM4838’s θJA is 20˚C/W. In the MTE package soldered to a DAP pad that expands to a copper area of 2in2 on a PCB, the LM4838MTE’s θJA is 41˚C/W. For the LM4838MT package, θJA = 80˚C/W. At any given ambient temperature TA, use Equation (4) to find the maximum internal power dissipation supported by the IC packaging. Rearranging Equation (4) and substituting PDMAX for PDMAX' results in Equation (5). This equation gives the maximum ambient temperature that still allows maximum stereo power dissipation without violating the LM4838’s maximum junction temperature. TA = TJMAX – 2*PDMAX θJA SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4838’s performance requires properly selecting external components. Though the LM4838 operates well when using external components with wide tolerances, best performance is achieved by optimizing component values. The LM4838 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 circuits demand input signals with greater voltage swings to achieve maximum output power. Fortunately, many signal sources such as audio 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. (5) For a typical application with a 5V power supply and an 4Ω load, the maximum ambient temperature that allows maximum stereo power dissipation without exceeding the maximum junction temperature is approximately 99˚C for the LQ package and 45˚C for the MTE package. TJMAX = PDMAX θJA + TA (6) Equation (6) gives the maximum junction temperature TJMAX. If the result violates the LM4838’s 150˚C TJMAX, reduce the maximum junction temperature by reducing the power supply voltage or increasing the load resistance. Further allowance should be made for increased ambient temperatures. www.national.com 16 (Continued) CB INPUT CAPACITOR VALUE SELECTION Amplifying the lowest audio frequencies requires a high value input coupling capacitor (0.33µF in Figure 2), but high value capacitors 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 150 Hz. Applications using speakers with this limited frequency response reap little improvement by using a large input capacitor. 0.1µF 20ms 0.22µF 44ms 0.47µF 94ms 1.0µF 200ms Applications such as notebook computers can take advantage of a docking station to connect to external devices such as monitors or audio/visual equipment that sends or receives line level signals. The LM4838 has two outputs, Right Dock and Left Dock, which connect to outputs of the internal input amplifiers that drive the volume control inputs. These input amplifiers can drive loads of > 1kΩ (such as powered speakers) with a rail-to-rail signal. Since the output signal present on the RIGHT DOCK and LEFT DOCK pins is biased to VDD/2, coupling capacitors should be connected in series with the load when using these outputs. Typical values for the output coupling capacitors are 0.33µF to 1.0µF. If polarized coupling capacitors are used, connect their "+" terminals to the respective output pin, see Figure 2. Since the DOCK outputs precede the internal volume control, the signal amplitude will be equal to the input signal’s magnitude and cannot be adjusted. However, the input amplifier’s closed-loop gain can be adjusted using external resistors. These 20k resistors (RFR, RFL) are shown in Figure 2 and they set each input amplifier’s gain to -1. Use Equation 7 to determine the input and feedback resistor values for a desired gain. (8) - AVR = RFR/RIR and - AVL = RFL/RIL Adjusting the input amplifier’s gain sets the minimum gain for that channel. Although the single ended output of the Bridge Output Amplifiers can be used to drive line level outputs, it is recommended that the R & L Dock Outputs simpler signal path be used for better performance. (7) As an example when using a speaker with a low frequency limit of 150Hz, the input coupling capacitor, using Equation (7), is 0.053µF. The 0.33µF input coupling capacitor shown in Figure 2 allows the LM4838 to drive a high efficiency, full range speaker whose response extends below 30Hz. BEEP DETECT FUNCTION Computers and notebooks produce a system “beep“ signal that drives a small speaker. The speaker’s auditory output signifies that the system requires user attention or input. To accommodate this system alert signal, the LM4838’s beep input pin is a mono input that accepts the beep signal. Internal level detection circuitry at this input monitors the beep signal’s magnitude. When a signal level greater than VDD/2 is detected on the BEEP IN pin, the bridge output amplifiers are enabled. The beep signal is amplified and applied to the load connected to the output amplifiers. A valid beep signal will be applied to the load even when MUTE is active. Use the input resistors connected between the BEEP IN pin and the stereo input pins to accommodate different beep signal amplitudes. These resistors (RBEEP) are shown as 200kΩ devices in Figure 2. Use higher value resistors to reduce the gain applied to the beep signal. The resistors must be used to pass the beep signal to the stereo inputs. The BEEP IN pin is used only to detect the beep signal’s magnitude: it does not pass the signal to the output amplifiers. The LM4838’s shutdown mode must be deactivated before a system alert signal is applied to BEEP IN pin. OPTIMIZING CLICK AND POP REDUCTION PERFORMANCE The LM4838 contains circuitry that minimizes turn-on and shutdown transients or “clicks and pops”. For this discussion, turn-on refers to either applying the power supply voltage or when the shutdown mode is deactivated. While the power supply is ramping to its final value, the LM4838’s internal amplifiers are configured as unity gain buffers. An internal current source changes the voltage of the BYPASS pin in a controlled, linear manner. Ideally, the input and outputs track the voltage applied to the BYPASS pin. 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 the BYPASS pin is stable, the device becomes fully operational. 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: 0.01µF TON DOCKING STATION INTERFACE Besides effecting system cost and size, the input coupling capacitor has an affect on the LM4838’s click and pop performance. When the supply voltage is first applied, a transient (pop) is created as the charge on the input capacitor changes from zero to a quiescent state. The magnitude of the pop is directly proportional to the input capacitor’s size. Higher value capacitors need more time to reach a quiescent DC voltage (usually VDD/2) when charged with a fixed current. The amplifier’s output charges the input capacitor through the feedback resistor, Rf. Thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired −6dB frequency. As shown in Figure 2, the input resistor (RIR, RIL = 20k) ( and the input capacitor (CIR, CIL = 0.33µF) produce a −6dB high pass filter cutoff frequency that is found using Equation (7). CB LM4838 Application Information TON 2ms 17 www.national.com LM4838 Application Information (Continued) MICRO-POWER SHUTDOWN The voltage applied to the SHUTDOWN pin controls the LM4838’s shutdown function. Activate micro-power shutdown by applying VDD to the SHUTDOWN pin. When active, the LM4838’s micro-power shutdown feature turns off the amplifier’s bias circuitry, reducing the supply current. The logic threshold is typically VDD/2. The low 0.7 µA typical shutdown current is achieved by applying a voltage that is as near as VDD as possible to the SHUTDOWN pin. A voltage that is less than VDD 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 10kΩ pull-up resistor between the SHUTDOWN pin and VDD. Connect the switch between the SHUTDOWN pin and ground. Select normal amplifier operation by closing the switch. Opening the switch connects the SHUTDOWN pin to VDD through the pull-up 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 need for a pull up resistor. 20013304 FIGURE 3. Headphone Sensing Circuit HP SENSE FUNCTION ( Head Phone In ) Applying a voltage between 4V and VDD to the LM4838’s HP-IN headphone control pin turns off the amps that drive the Left out "+" and Right out "+" pins. This action mutes a bridged-connected load. Quiescent current consumption is reduced when the IC is in this single-ended mode. Figure 3 shows the implementation of the LM4838’s headphone control function. With no headphones connected to the headphone jack, the R1-R2 voltage divider sets the voltage applied to the HP SENSE pin at approximately 50mV. This 50mV puts the LM4838 into bridged mode operation. The output coupling capacitor blocks the amplifier’s half supply DC voltage, protecting the headphones. The HP-IN threshold is set at 4V. While the LM4838 operates in bridged mode, the DC potential across the load is essentially 0V. Therefore, even in an ideal situation, the output swing cannot cause a false single-ended trigger. Connecting headphones to the headphone jack disconnects the headphone jack contact pin from R2 and allows R1 to pull the HP Sense pin up to VDD through R4. This enables the headphone function, turns off both of the "+" output amplifiers, and mutes the bridged speaker. The remaining single-ended amplifiers then drive the headphones, whose impedance is in parallel with resistors R2 and R3. These resistors have negligible effect on the LM4838’s output drive capability since the typical impedance of headphones is 32Ω. Figure 3 also shows the suggested headphone jack electrical connections. The jack is designed to mate with a threewire plug. The plug’s tip and ring should each carry one of the two stereo output signals, whereas the sleeve should carry the ground return. A headphone jack with one control pin contact is sufficient to drive the HP-IN pin when connecting headphones. A microprocessor or a switch can replace the headphone jack contact pin. When a microprocessor or switch applies a voltage greater than 4V to the HP-IN pin, a bridge-connected speaker is muted and the single ended output amplifiers 1A and 2A will drive a pair of headphones. MODE FUNCTION The LM4838’s MODE function has 2 states controlled by the voltage applied to the MODE pin. Mode 0, selected by applying 0V to the MODE pin, forces the LM4838 to effectively function as a "line-out," unity-gain amplifier. Mode 1, which uses the internal DC controlled volume control is selected by applying VDD to the MODE pin. This mode sets the amplifier’s gain according to the DC voltage applied to the DC VOL CONTROL pin. Unanticipated gain behavior can be prevented by connecting the MODE pin to VDD or ground. Note: Do not let the mode pin float. MUTE FUNCTION The LM4838 mutes the amplifier and DOCK outputs when VDD is applied to the MUTE pin. Even while muted, the LM4838 will amplify a system alert (beep) signal whose magnitude satisfies the BEEP DETECT circuitry. Applying 0V to the MUTE pin returns the LM4838 to normal, unmuted operation. Prevent unanticipated mute behavior by connecting the MUTE pin to VDD or ground. Do not let the mute pain float. www.national.com 18 In some cases a designer may want to improve the low frequency response of the bridged amplifier or incorporate a bass boost feature. This bass boost can be useful in systems where speakers are housed in small enclosures. A resistor, RLFE, and a capacitor, CLFE, in parallel, can be placed in series with the feedback resistor of the bridged amplifier as seen in Figure 4. (Continued) GAIN SELECT FUNCTION (Bass Boost) The LM4838 features selectable gain, using either internal or external feedback resistors. Either set of feedback resistors set the gain of the output amplifiers. The voltage applied to the GAIN SELECT pin controls which gain is selected. Applying VDD to the GAIN SELECT pin selects the external gain mode. Applying 0V to the GAIN SELECT pin selects the internally set unity gain. 20013311 FIGURE 4. Low Frequency Enhancement The LM4838 volume control consists of 31 steps that are individually selected by a variable DC voltage level on the volume control pin. The range of the steps, controlled by the DC voltage, are from 0dB - 78dB. Each gain step corresponds to a specific input voltage range, as shown in table 2. To minimize the effect of noise on the volume control pin, which can affect the selected gain level, hysteresis has been implemented. The amount of hysteresis corresponds to half of the step width, as shown in Volume Control Characterization Graph (DS200133-40). For highest accuracy, the voltage shown in the ’recommended voltage’ column of the table is used to select a desired gain. This recommended voltage is exactly halfway between the two nearest transitions to the next highest or next lowest gain levels. The gain levels are 1dB/step from 0dB to -6dB, 2dB/step from -6dB to -36dB, 3dB/step from -36dB to -47dB, 4dB/step from -47db to -51dB, 5dB/step from -51dB to -66dB, and 12dB to the last step at -78dB. At low, frequencies CLFE is a virtual open circuit and at high frequencies, its nearly zero ohm impedance shorts RLFE. The result is increased bridge-amplifier gain at low frequencies. The combination of RLFE and CLFE form a -6dB corner frequency at fC = 1/(2πRLFEC LFE) (9) The bridged-amplifier low frequency differential gain is: AVD = 2(RF + RLFE) / R i (10) Using the component values shown in Figure 1 (RF = 20kΩ, RLFE = 20kΩ, and CLFE = 0.068µF), a first-order, -6dB pole is created at 120Hz. Assuming R i = 20kΩ, the low frequency differential gain is 4. The input (Ci) and output (CO) capacitor values must be selected for a low frequency response that covers the range of frequencies affected by the desired bass-boost operation. DC VOLUME CONTROL The LM4838 has an internal stereo volume control whose setting is a function of the DC voltage applied to the DC VOL CONTROL pin. 19 www.national.com LM4838 Application Information LM4838 Application Information (Continued) VOLUME CONTROL TABLE ( Table 2 ) Gain (dB) Voltage Range (% of Vdd) Low Voltage Range (Vdd = 3) Recommended Low High Recommended Low High Recommended 0 77.5% 100.00% 100.000% 3.875 5.000 5.000 2.325 3.000 3.000 -1 75.0% 78.5% 76.875% 3.750 3.938 3.844 2.250 2.363 2.306 -2 72.5% 76.25% 74.375% 3.625 3.813 3.719 2.175 2.288 2.231 -3 70.0% 73.75% 71.875% 3.500 3.688 3.594 2.100 2.213 2.156 -4 67.5% 71.25% 69.375% 3.375 3.563 3.469 2.025 2.138 2.081 -5 65.0% 68.75% 66.875% 3.250 3.438 3.344 1.950 2.063 2.006 -6 62.5% 66.25% 64.375% 3.125 3.313 3.219 1.875 1.988 1.931 -8 60.0% 63.75% 61.875% 3.000 3.188 3.094 1.800 1.913 1.856 -10 57.5% 61.25% 59.375% 2.875 3.063 2.969 1.725 1.838 1.781 -12 55.0% 58.75% 56.875% 2.750 2.938 2.844 1.650 1.763 1.706 -14 52.5% 56.25% 54.375% 2.625 2.813 2.719 1.575 1.688 1.631 -16 50.0% 53.75% 51.875% 2.500 2.688 2.594 1.500 1.613 1.556 -18 47.5% 51.25% 49.375% 2.375 2.563 2.469 1.425 1.538 1.481 -20 45.0% 48.75% 46.875% 2.250 2.438 2.344 1.350 1.463 1.406 -22 42.5% 46.25% 44.375% 2.125 2.313 2.219 1.275 1.388 1.331 -24 40.0% 43.75% 41.875% 2.000 2.188 2.094 1.200 1.313 1.256 -26 37.5% 41.25% 39.375% 1.875 2.063 1.969 1.125 1.238 1.181 -28 35.0% 38.75% 36.875% 1.750 1.938 1.844 1.050 1.163 1.106 -30 32.5% 36.25% 34.375% 1.625 1.813 1.719 0.975 1.088 1.031 -32 30.0% 33.75% 31.875% 1.500 1.688 1.594 0.900 1.013 0.956 -34 27.5% 31.25% 29.375% 1.375 1.563 1.469 0.825 0.937 0.881 -36 25.0% 28.75% 26.875% 1.250 1.438 1.344 0.750 0.862 0.806 -39 22.5% 26.25% 24.375% 1.125 1.313 1.219 0.675 0.787 0.731 -42 20.0% 23.75% 21.875% 1.000 1.188 1.094 0.600 0.712 0.656 -45 17.5% 21.25% 19.375% 0.875 1.063 0.969 0.525 0.637 0.581 -47 15.0% 18.75% 16.875% 0.750 0.937 0.844 0.450 0.562 0.506 -51 12.5% 16.25% 14.375% 0.625 0.812 0.719 0.375 0.487 0.431 -56 10.0% 13.75% 11.875% 0.500 0.687 0.594 0.300 0.412 0.356 -61 7.5% 11.25% 9.375% 0.375 0.562 0.469 0.225 0.337 0.281 -66 5.0% 8.75% 6.875% 0.250 0.437 0.344 0.150 0.262 0.206 -78 0.0% 6.25% 0.000% 0.000 0.312 0.000 0.000 0.187 0.000 www.national.com High Voltage Range (Vdd = 5) 20 (Continued) The last step in this design example is setting the amplifier’s −6dB frequency bandwidth. To achieve the desired ± 0.25dB pass band magnitude variation limit, the low frequency response must extend to at least 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 AUDIO POWER AMPLIFIER DESIGN Audio Amplifier Design: Driving 1W into an 8Ω Load The following are the desired operational parameters: Power Output: 1 WRMS Load Impedance: 8Ω Input Level: 1 VRMS Input Impedance: Bandwidth: 20 kΩ 100 Hz−20 kHz ± 0.25 dB fL = 100Hz/5 = 20Hz (14) fH = 20kHz x 5 = 100kHz (15) and an The design begins by specifying the minimum supply voltage necessary to obtain the specified output power. One way to 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 (10), 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 (10). The result is Equation (11). As mentioned in the Selecting Proper External Components section, Ri (Right & Left) and Ci (Right & Left) create a highpass filter that sets the amplifier’s lower bandpass frequency limit. Find the input coupling capacitor’s value using Equation (14). Ci≥ 1/(2πRifL) (16) 1/(2π*20kΩ*20Hz) = 0.397µF (17) The result is (11) VDD ≥ (VOUTPEAK+ (VODTOP + VODBOT)) Use a 0.39µF capacitor, the closest standard value. (12) The product of the desired high frequency cutoff (100kHz in this example) and the differential gain AVD, determines the upper passband response limit. With AVD = 3 and fH = 100kHz, the closed-loop gain bandwidth product (GBWP) is 300kHz. This is less than the LM4838’s 3.5MHz GBWP. With this margin, the amplifier can be used in designs that require more differential gain while avoiding performance,restricting bandwidth limitations. The Output Power vs Supply Voltage graph for an 8Ω load indicates a minimum supply voltage of 4.6V. This is easily met by the commonly used 5V supply voltage. The additional voltage creates the benefit of headroom, allowing the LM4838 to produce peak output power in excess of 1W without clipping or other audible distortion. The choice of supply voltage must also not create a situation that violates of maximum power dissipation as explained above in the Power Dissipation section. After satisfying the LM4838’s power dissipation requirements, the minimum differential gain needed to achieve 1W dissipation in an 8Ω load is found using Equation (12). Recommended Printed Circuit Board Layout The following figures show the recommended PC board layouts that are optimized for the different package options of the LM4838 and associated external components. This circuit is designed for use with an external 5V supply and 4Ω speakers. This circuit board is easy to use. Apply 5V and ground to the board’s VDD and GND pads, respectively. Connect 4Ω speakers between the board’s −OUTA and +OUTA and OUTB and +OUTB pads. (13) Thus, a minimum overall gain of 2.83 allows the LM4838’s to reach full output swing and maintain low noise and THD+N performance. 21 www.national.com LM4838 Application Information LM4838 Recommended Printed Circuit Board Layout (Continued) 20013377 FIGURE 5. Recommended LQ PC Board Layout: Component-Side Silkscreen 20013378 FIGURE 6. Recommended LQ PC Board Layout: Component-Side Layout www.national.com 22 LM4838 Recommended Printed Circuit Board Layout (Continued) 20013379 FIGURE 7. Recommended LQ PC Board Layout: Upper Inner-Layer Layout 20013380 FIGURE 8. Recommended LQ PC Board Layout: Lower Inner-Layer Layout 23 www.national.com LM4838 Recommended Printed Circuit Board Layout (Continued) 20013381 FIGURE 9. Recommended LQ PC Board Layout: Bottom-Side Layout www.national.com 24 LM4838 Analog Audio LM4838 LLP28 Eval Board Assembly Part Number: 980011368-100 Revision: A1 Bill of Material Item Part Number Part Description Qty Ref Designator 1 551011368-001 LM4838 Eval Board PCB etch 001 1 10 482911368-001 LM4838 28L LLP 1 U4 20 151911368-001 Cer Cap 0.068µF 50V 10% 1206 2 CBS1, CBS2 25 152911368-001 Tant Cap 0.1µF 10V 10% Size = A 3216 3 CS1, CS2, CV 26 152911368-002 Tant Cap 0.33µF 10V 10% Size = A 3216 3 Cin1, Cin2, Cin3 27 152911368-003 Tant Cap 1µF 16V 10% Size = A 3216 3 CB, C01, C02 28 152911368-004 Tant Cap 10µF 10V 10% Size = C 6032 1 CS3 29 152911368-005 Tant Cap 220µF 16V 10% Size = D 7343 2 Cout1, Cout2 30 472911368-001 Res 1.5K Ohm 1/8W 1% 1206 2 RL1, RL2 31 472911368-002 Res 20k Ohm 1/8W 1% 1206 10 Rin1, Rin2, RF1, RF2 Remark Rl1, Rl2, RBS1, RBS2 Rdock1, Rdock2 32 472911368-003 Res 100k Ohm 1/8W 1% 1206 2 RS, RPU 33 472911368-004 Res 200k Ohm 1/16W 1% 0603 2 Rbeep1, Rbeep2 40 131911368-001 Stereo Headphone Jack W/ Switch 1 U2 Mouser # 161-3500 41 131911368-002 Slide Switch 4 Mode, Mute, Gain, SD Mouser # 10SP003 42 131911368-003 Potentiometer 1 U1 Mouser # 317-290-100K 43 131911368-004 RCA Jack 3 RightIn, BeepIn, LeftIn Mouser # 16PJ097 44 131911368-005 Banana Jack, Black 3 GND, Right Out-, Left Out- Mouser # ME164-6219 45 131911368-006 Banana Jack, Red 3 Vdd, Right Out+, Left Out+ Mouser # ME164-6218 25 www.national.com LM4838 LM4838 MT & MTE Demo Board Artwork 20013382 Top Layer SilkScreen 20013383 Top Layer TSSOP www.national.com 26 LM4838 LM4838 MT & MTE Demo Board Artwork (Continued) 20013385 Inner Layer (2) LM4838MT/MTE 20013386 Inner Layer (3) LM4838MT/MTE 27 www.national.com LM4838 LM4838 MT & MTE Demo Board Artwork (Continued) 20013384 Bottom Layer TSSOP Analog Audio LM4838 TSSOP Eval Board Assembly Part Number: 980011373-100 Revision: A Bill of Material Item Part Number Part Description Qty 1 551011373-001 LM4838 Eval Board PCB etch 001 1 10 482911373-001 LM4838 TSSOP 1 20 151911368-001 Cer Cap 0.068µF 50V 10% 1206 2 25 152911368-001 Tant Cap 0.1µF 10V 10% 3 Size = A 3216 CS, CS, CV 26 152911368-002 Tant Cap 0.33µF 10V 10% Size = A 3216 3 CIN 27 152911368-003 Tant Cap 1µF 16V 10% Size = A 3216 3 CB, CO1, CO2 28 152911368-004 Tant Cap 10µF 10V 10% Size = C 6032 1 CS1 29 152911368-005 Tant Cap 220µF 16V 10% 2 Size = D 7343 CoutL, R 30 472911368-001 Res 1.5K Ohm 1/8W 1% 1206 2 RL 31 472911368-002 Res 20K Ohm 1/8W 1% 1206 10 RIN(4), RF(2), RDOCK(2), RBS(2) 32 472911368-003 Res 100K Ohm 1/8W 1% 1206 2 RPU, RS 33 472911368-004 Res 200K Ohm 1/16W 1% 0603 2 RBEEP www.national.com 28 Ref Designator CBS Remark LM4838 Analog Audio LM4838 TSSOP Eval Board Assembly Part Number: 980011373-100 Revision: A Bill of Material (Continued) Item Part Number Part Description Qty 40 131911368-001 Stereo Headphone Jack W/ Switch 1 Mouser # 161-3500 41 131911368-002 Slide Switch 4 mute, mode, Gain, Mouser # SD 10SP003 42 131911368-003 Potentiometer 1 Volume Control Mouser # 317-2090-100K 43 131911368-004 RCA Jack 3 Right-In, Beep-In, Left-In Mouser # 16PJ097 44 131911368-005 Banana Jack, Black 3 Mouser # ME164-6219 45 131911368-006 Banana Jack, Red 3 Mouser # ME164-6218 29 Ref Designator Remark www.national.com LM4838 LM4838 ITL Demo Board Artworks 20013392 FIGURE 10. LM4838 micro SMD Silk Screen 20013389 FIGURE 11. LM4838 micro SMD Top Layer www.national.com 30 LM4838 LM4838 ITL Demo Board Artworks (Continued) 20013390 FIGURE 12. LM4838 micro SMD Upper Inner Layer 20013391 FIGURE 13. LM4838 micro SMD Lower Inner Layer 31 www.national.com LM4838 LM4838 ITL Demo Board Artworks (Continued) 20013393 FIGURE 14. LM4838 micro SMD Bottom Layer www.national.com 32 LM4838 Analog Audio LM4838 TLA36 Board Bill of Material Part Description µΩ Qty Reference Designator LM4838 TLA36 Evaluation Board PCB 1 P/N: 551011755 - 002 rev A LM4838ITL 1 U1 Ceramic Capacitor 0.068µF 50V 10% Size = 1206 2 CBS1, CBS2 Tantalum Capacitor 0.1µF 10V 10% Size = 1206 3 CS1, CS2, CV Tantalum Capacitor 0.33µF 10V 10% Size = 1206 3 CIN1, CIN2, CIN3 Tantalum Capacitor 1.0µF 16V 10% Size = 1210 4 CS3, CB, CO1, CO2 Tantalum Capacitor 220µF 16V 10% Size = 7343 2 COUT1, COUT2 Resistor 1.5kΩ 1/10W 1% Size = 0805 2 RL1, RL2 Resistor 20kΩ 1/10W 1% Size = 0805 10 RIN1, RIN2, RF1, RF2, Rl1, Rl2, RBS1, RBS2, RDOCK1, RDOCK2 Resistor 100kΩ 1/10W 1% Size = 0805 2 RS, RPU Resistor 120kΩ 1/10W 1% Size = 0805 2 RBEEP1, RBEEP2 Resistor 1MΩ 1/10W 1% Size = 0805 1 RV Jumper Header Vertical Mount 0.100” spacing 1 J1 (Docking RT LF) RCA Jack PCB mount 3 J2 (LeftIn), J3 (Beep In), J4 (Right In) Banana Jack, Black 3 J5B (GND), J6A (Right Out -), J7A (Left Out -) Banana Jack, Red 3 J5A (VDD), J6B (Right Out +), J7B (Left Out +) Stereo Headphone Jack W/Switch 1 J8 Single Turn Potentiometer 100kΩ 20% 1 J9 Jumper Header Vertical Mount 0.100” spacing 3x4 1 Mute, SD, Gain, Mode Jumper Header Vertical Mount 0.100” spacing 1x3 1 DC IN 33 www.national.com LM4838 Physical Dimensions inches (millimeters) unless otherwise noted LLP Package Order Number LM4838LQ NS Package Number LQA028AA For Exposed-DAP LLP www.national.com 34 LM4838 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) TSSOP Package Order Number LM4838MT NS Package Number MTC28 for TSSOP Exposed-DAP TSSOP Package Order Number LM4838MTE NS Package Number MXA28A for Exposed-DAP TSSOP 35 www.national.com LM4838 Stereo 2W Audio Power Amplifiers with DC Volume Control and Selectable Gain Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 36-Bump micro SMD Order Number LM4838ITL, LM4838ITLX NS Package Number TLA36AAA X1 = 3.000 ± 0.03 X2 = 3.000 ± 0.03 X3 = 0.600 ± 0.075 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. National Semiconductor Americas Customer Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 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. National Semiconductor Asia Pacific Customer Support Center Fax: 65-6250 4466 Email: [email protected] Tel: 65-6254 4466 National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: [email protected] Tel: 81-3-5639-7560 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.