LM4899 Boomer ® Audio Power Amplifier Series 1 Watt Fully

LM48991 Watt Fully Differential Audio Power Amplifier WithShutdown Select and Fixed 6dB GainGeneral DescriptionThe LM4899 is a fully differential audio power amplifierprimarily designed for demanding applications in mobilephones and other portable communication device applica-tions. It is capable of delivering 1 watt of continuous averagepower to an 8Ω load with less than 1% distortion (THD+N)from a 5VDC power supply.

Boomer audio power amplifiers were designed specifically toprovide high quality output power with a minimal amount ofexternal components. The LM4899 does not require outputcoupling capacitors or bootstrap capacitors, and therefore isideally suited for mobile phone and other low voltage appli-cations where minimal power consumption is a primary re-quirement.

The LM4899 features a low-power consumption shutdownmode. To facilitate this, Shutdown may be enabled by eitherlogic high or low depending on mode selection. Driving theshutdown mode pin either high or low enables the shutdownselect pin to be driven in a likewise manner to enable Shut-down. Additionally, the LM4899 features an internal thermalshutdown protection mechanism.

The LM4899 contains advanced pop & click circuitry whichvirtually eliminates noises which would otherwise occur dur-ing turn-on and turn-off transitions.

The LM4899 has an internally fixed gain of 6dB.

Key Specificationsj Improved PSRR at 217Hz 83dB

j Power Output at 5.0V & 1% THD 1.0W(typ.)

j Power Output at 3.3V & 1% THD 400mW(typ.)

j Shutdown Current 0.1µA(typ.)

Featuresn Fully differential amplificationn Internal-gain-setting resistorsn Available in space-saving packages micro SMD, MSOP

and LLPn Ultra low current shutdown moden Can drive capacitive loads up to 500pFn Improved pop & click circuitry which virtually eliminates

noises during turn-on and turn-off transitionsn 2.4 - 5.5V operationn No output coupling capacitors, snubber networks or

bootstrap capacitors requiredn Shutdown high or low selectivity

Applicationsn Mobile phonesn PDAsn Portable electronic devices

Connection Diagrams9 Bump micro SMD Package 9 Bump micro SMD Marking

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Top ViewOrder Number LM4899ITL, LM4899ITLX

See NS Package Number TLA09AAA

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X - Date CodeT - Die Run Traceability

G - Boomer FamilyC1 - LM4899ITL

Boomer® is a registered trademark of National Semiconductor Corporation.

July 2003LM

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Connection Diagrams (Continued)

Mini Small Outline (MSOP) Package MSOP Marking

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Top ViewOrder Number LM4899MM

See NS Package Number MUB10A

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Z - Assembly CodeX - Date Code

TT - Die Run TraceabilityG - Boomer Family

B1 - LM4899MM

LD Package LD Marking

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Top ViewOrder Number LM4899LD

See NS Package Number LDA10B

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Z - Assembly CodeXY - Date Code

TT - Die Run TraceabilityL4899 - LM4899LD

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Typical Application

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FIGURE 1. Typical Audio Amplifier Application Circuit

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Absolute Maximum Ratings (Note 2)

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 −65˚C to +150˚C

Input Voltage −0.3V to VDD +0.3V

Power Dissipation (Note 3) Internally Limited

ESD Susceptibility (Note 4) 2000V

ESD Susceptibility (Note 5) 200V

Junction Temperature 150˚C

Thermal Resistance

θJC (LD) 12˚C/W

θJA (LD) 63˚C/W

θJA (micro SMD) 220˚C/W

θJC (MSOP) 56˚C/W

θJA (MSOP) 190˚C/W

Soldering Information

See AN-1112 "microSMD Wafers Level Chip ScalePackage".

Operating RatingsTemperature Range

TMIN ≤ TA ≤ TMAX −40˚C ≤ TA ≤ +85˚C

Supply Voltage 2.4V ≤ VDD ≤ 5.5V

Electrical Characteristics VDD = 5V (Notes 1, 2, 8)The following specifications apply for VDD = 5V and 8Ω load unless otherwise specified. Limits apply for TA = 25˚C.

Symbol Parameter Conditions

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(Limits)Typical Limit

(Note 6) (Note 7)

IDD Quiescent Power Supply Current VIN = 0V, no LoadVIN = 0V, RL = 8Ω

35

610

mA (max)

ISD Standby Current VSDMODE = VSHUTDOWN = GND 0.1 1 µA (max)

Po Output Power

THD = 1% (max); f = 1 kHz

LM4899LD, RL = 4Ω (Note 11) 1.4W (min)

LM4899, RL = 8Ω 1 0.9

THD+N Total Harmonic Distortion+Noise Po = 0.4 Wrms; f = 1kHz 0.05 %

PSRR Power Supply Rejection Ratio

Vripple = 200mV sine p-p

f = 217Hz (Note 9) 83

dB (min)f = 1kHz (Note 9) 90

f = 217Hz (Note 10) 83 71

f = 1kHz (Note 10) 83 71

CMRR Common-Mode Rejection Ratio f = 217Hz, VCM = 200mVpp 50 dB

VOS Output Offset VIN = 0V 2 mV

VSDIH Shutdown Voltage Input High SD Mode = GND 0.9 V

VSDIL Shutdown Voltage Input Low SD Mode = GND 0.7 V

VSDIH Shutdown Voltage Input High SD Mode = VDD 0.9 V

VSDIL Shutdown Voltage Input Low SD Mode = VDD 0.7 V

Electrical Characteristics VDD = 3V (Notes 1, 2, 8)The following specifications apply for VDD = 3V and 8Ω load unless otherwise specified. Limits apply for TA = 25˚C.


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(Note 6) (Note 7)

IDD Quiescent Power Supply Current VIN = 0V, no LoadVIN = 0V, RL = 8Ω

2.54

5.59

mA (max)

ISD Standby Current VSDMODE = VSHUTDOWN = GND 0.1 1 µA (max)

Po Output PowerTHD = 1% (max); f = 1kHzLM4899, RL = 8Ω

0.35 W

THD+N Total Harmonic Distortion+Noise Po = 0.25Wrms; f = 1kHz 0.3 %

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Electrical Characteristics VDD = 3V (Notes 1, 2, 8)The following specifications apply for VDD = 3V and 8Ω load unless otherwise specified. Limits apply for TA =25˚C. (Continued)


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(Note 6) (Note 7)

PSRR Power Supply Rejection Ratio

Vripple = 200mV sine p-p

f = 217Hz (Note 9) 83

dBf = 1kHz (Note 9) 84

f = 217Hz (Note 10) 83

f = 1kHz (Note 10) 83

CMRR Common-Mode Rejection Ratio f = 217Hz, VCM = 200mVpp 50 dB

VOS Offset Voltage VIN = 0V 2 mV

VSDIH Shutdown Voltage Input High SD Mode = GND 0.8 V

VSDIL Shutdown Voltage Input Low SD Mode = GND 0.6 V

VSDIH Shutdown Voltage Input High SD Mode = VDD 0.8 V

VSDIL Shutdown Voltage Input Low SD Mode = VDD 0.6 V

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device isfunctional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions whichguarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limitis given, however, the typical value is a good indication of device performance.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature TA. The maximumallowable power dissipation is PDMAX = (TJMAX–TA)/θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4899, see power deratingcurrents for additional information.

Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor.

Note 5: Machine Model, 220pF–240pF discharged through all pins.

Note 6: Typicals are measured at 25˚C and represent the parametric norm.

Note 7: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

Note 8: For micro SMD only, shutdown current is measured in a Normal Room Environment. Exposure to direct sunlight will increase ISD by a maximum of 2µA.

Note 9: Unterminated input.

Note 10: 10Ω terminated input.

Note 11: : When driving 4Ω loads from a 5V power supply, the LM4899LD must be mounted to a circuit board with the exposed-DAP area soldered down to a 1sq.in plane of 1oz. copper.

External Components Description (Figure 1)

Components Functional Description

1. CS Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassingsection for information concerning proper placement and selection of the supply bypass capacitor.

2. CB Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of ExternalComponents, for information concerning proper placement and selection of CB.

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Typical Performance CharacteristicsLD Specific Characteristics

THD+N vs Output PowerVDD = 5V, RL = 4Ω

THD+N vs FrequencyVDD = 5V, RL = 4Ω, PO = 1W

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LM4899LDPower Dissipation vs Output Power

LM4899LDPower Derating Curve

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Typical Performance CharacteristicsNon-LD Specific Characteristics

THD+N vs FrequencyVDD = 5V, RL = 8Ω, PO = 400mW


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THD+N vs FrequencyVDD = 2.6V, RL = 8Ω, PO = 150mW

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THD+N vs FrequencyVDD = 2.6V, RL = 4Ω, PO = 150mW


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Typical Performance CharacteristicsNon-LD Specific Characteristics (Continued)



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THD+N vs Output PowerVDD = 2.6V, RL = 8Ω

THD+N vs Output PowerVDD = 2.6V, RL = 4Ω

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PSRR vs FrequencyVDD = 5V, RL = 8Ω, Input 10Ω Terminated

PSRR vs FrequencyVDD = 3V, RL = 8Ω, Input 10Ω Terminated

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Output Power vs Supply VoltageRL = 8Ω

Output Power vs Supply VoltageRL = 4Ω

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Power Dissipation vsOutput Power


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Output Power vsLoad Resistance

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Supply Current vs Shutdown VoltageShutdown Low

Supply Current vs Shutdown VoltageShutdown High

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Clipping (Dropout) Voltage vsSupply Voltage Open Loop Frequency Response

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Power Derating CurveNoise Floor

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CMRR vs FrequencyVDD = 5V, RL = 8Ω, 200mVpp

CMRR vs FrequencyVDD = 3V, RL = 8Ω, 200mVpp

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PSRR vs Common Mode VoltageVDD = 5V

PSRR vs Common Mode VoltageVDD = 3V, RL = 8Ω, 217Hz, 200mVpp

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Application Information

DIFFERENTIAL AMPLIFIER EXPLANATION

The LM4899 is a fully differential audio amplifier that fea-tures differential input and output stages. Internally this isaccomplished by two circuits: a differential amplifier and acommon mode feedback amplifier that adjusts the outputvoltages so that the average value remains VDD/2. TheLM4899 features precisely matched internal gain-setting re-sistors, thus eliminating the need for external resistors andfixing the differential gain at AVD = 6dB.

A differential amplifier works in a manner where the differ-ence between the two input signals is amplified. In mostapplications, this would require input signals that are 180˚out of phase with each other.

The LM4899 provides what is known as a "bridged mode"output (bridge-tied-load, BTL). This results in output signalsat Vo1 and Vo2 that are 180˚ out of phase with respect toeach other. Bridged mode operation is different from thesingle-ended amplifier configuration that connects the loadbetween the amplifier output and ground. A bridged amplifierdesign has distinct advantages over the single-ended con-figuration: it provides differential drive to the load, thus dou-bling maximum possible output swing for a specific supplyvoltage. Four times the output power is possible comparedwith a single-ended amplifier under the same conditions.This increase in attainable output power assumes that theamplifier is not current limited or clipped.

A bridged configuration, such as the one used in theLM4899, also creates a second advantage over single-ended amplifiers. Since the differential outputs, Vo1 and Vo2,are biased at half-supply, no net DC voltage exists acrossthe load. BTL configuration eliminates the output couplingcapacitor required in single-supply, single-ended amplifierconfigurations. If an output coupling capacitor is not used ina single-ended output configuration, the half-supply biasacross the load would result in both increased internal ICpower dissipation as well as permanent loudspeaker dam-age. Further advantages of bridged mode operation specificto fully differential amplifiers like the LM4899 include in-creased power supply rejection ratio, common-mode noisereduction, and click and pop reduction.

EXPOSED-DAP PACKAGE PCB MOUNTINGCONSIDERATIONS

The LM4899’s exposed-DAP (die attach paddle) package(LD) provide a low thermal resistance between the die andthe PCB to which the part is mounted and soldered. Thisallows rapid heat transfer from the die to the surroundingPCB copper traces, ground plane and, finally, surroundingair. The result is a low voltage audio power amplifier thatproduces 1.4W at ≤ 1% THD with a 4Ω load. This high poweris achieved through careful consideration of necessary ther-mal design. Failing to optimize thermal design may compro-mise the LM4899’s high power performance and activateunwanted, though necessary, thermal shutdown protection.The LD package must have its DAP soldered to a copperpad on the PCB. The DAP’s PCB copper pad is connected toa large plane of continuous unbroken copper. This planeforms a thermal mass and heat sink and radiation area.Place the heat sink area on either outside plane in the caseof a two-sided PCB, or on an inner layer of a board with more

than two layers. Connect the DAP copper pad to the innerlayer or backside copper heat sink area with 4 (2x2) vias.The via diameter should be 0.012in - 0.013in with a 0.050inpitch. Ensure efficient thermal conductivity by plating-through and solder-filling the vias.

Best thermal performance is achieved with the largest prac-tical copper heat sink area. If the heatsink and amplifiershare the same PCB layer, a nominal 2.5in2 (min) area isnecessary for 5V operation with a 4Ω load. Heatsink areasnot placed on the same PCB layer as the LM4899 should be5in2 (min) for the same supply voltage and load resistance.The last two area recommendations apply for 25˚C ambienttemperature. In all circumstances and conditions, the junc-tion temperature must be held below 150˚C to prevent acti-vating the LM4899’s thermal shutdown protection. TheLM4899’s power de-rating curve in the Typical PerformanceCharacteristics shows the maximum power dissipation ver-sus temperature. Example PCB layouts for the exposed-DAP TSSOP and LLP packages are shown in the Demon-stration Board Layout section. Further detailed and specificinformation concerning PCB layout, fabrication, and mount-ing an LLP package is available from National Semiconduc-tor’s package Engineering Group under application note AN-1187.

PCB LAYOUT AND SUPPLY REGULATIONCONSIDERATIONS FOR DRIVING 3Ω AND 4Ω LOADS

Power dissipated by a load is a function of the voltage swingacross the load and the load’s impedance. As load imped-ance decreases, load dissipation becomes increasingly de-pendent on the interconnect (PCB trace and wire) resistancebetween the amplifier output pins and the load’s connec-tions. Residual trace resistance causes a voltage drop,which results in power dissipated in the trace and not in theload as desired. For example, 0.1Ω trace resistance reducesthe output power dissipated by a 4Ω load from 1.4W to1.37W. This problem of decreased load dissipation is exac-erbated as load impedance decreases. Therefore, to main-tain the highest load dissipation and widest output voltageswing, PCB traces that connect the output pins to a loadmust be as wide as possible.

Poor power supply regulation adversely affects maximumoutput power. A poorly regulated supply’s output voltagedecreases with increasing load current. Reduced supplyvoltage causes decreased headroom, output signal clipping,and reduced output power. Even with tightly regulated sup-plies, trace resistance creates the same effects as poorsupply regulation. Therefore, making the power supplytraces as wide as possible helps maintain full output voltageswing.

POWER DISSIPATION

Power dissipation is a major concern when designing asuccessful amplifer, whether the amplifier is bridged orsingle-ended. Equation 2 states the maximum power dissi-pation point for a single-ended amplifier operating at a givensupply voltage and driving a specified output load.

PDMAX = (VDD)2 / (2π2RL) Single-Ended (1)

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Application Information (Continued)

However, a direct consequence of the increased power de-livered to the load by a bridge amplifier is an increase ininternal power dissipation versus a single-ended amplifieroperating at the same conditions.

PDMAX = 4*(VDD)2 / (2π2RL) Bridge Mode (2)

Since the LM4899 has bridged outputs, the maximum inter-nal power dissipation is 4 times that of a single-ended am-plifier. Even with this substantial increase in power dissipa-tion, the LM4899 does not require additional heatsinkingunder most operating conditions and output loading. FromEquation 3, assuming a 5V power supply and an 8Ω load,the maximum power dissipation point is 625mW. The maxi-mum power dissipation point obtained from Equation 3 mustnot be greater than the power dissipation results from Equa-tion 4:

PDMAX = (TJMAX - TA) / θJA (3)

The LM4899’s θJA in an MUA10A package is 190˚C/W.Depending on the ambient temperature, TA, of the systemsurroundings, Equation 4 can be used to find the maximuminternal power dissipation supported by the IC packaging. Ifthe result of Equation 3 is greater than that of Equation 4,then either the supply voltage must be decreased, the loadimpedance increased, the ambient temperature reduced, orthe θJA reduced with heatsinking. In many cases, largertraces near the output, VDD, and GND pins can be used tolower the θJA. The larger areas of copper provide a form ofheatsinking allowing higher power dissipation. For the typicalapplication of a 5V power supply, with an 8Ω load, themaximum ambient temperature possible without violating themaximum junction temperature is approximately 30˚C pro-vided that device operation is around the maximum powerdissipation point. Recall that internal power dissipation is afunction of output power. If typical operation is not around themaximum power dissipation point, the LM4899 can operateat higher ambient temperatures. Refer to the Typical Per-formance Characteristics curves for power dissipation in-formation.

POWER SUPPLY BYPASSING

As with any power amplifier, proper supply bypassing iscritical for low noise performance and high power supplyrejection ratio (PSRR). The capacitor location on both the

bypass and power supply pins should be as close to thedevice as possible. A larger half-supply bypass capacitorimproves PSRR because it increases half-supply stability.Typical applications employ a 5V regulator with 10µF and0.1µF bypass capacitors that increase supply stability. This,however, does not eliminate the need for bypassing thesupply nodes of the LM4899. Although the LM4899 willoperate without the bypass capacitor CB, although the PSRRmay decrease. A 1µF capacitor is recommended for CB. Thisvalue maximizes PSRR performance. Lesser values may beused, but PSRR decreases at frequencies below 1kHz. Theissue of CB selection is thus dependant upon desired PSRRand click and pop performance.

SHUTDOWN FUNCTION

In order to reduce power consumption while not in use, theLM4899 contains shutdown circuitry that is used to turn offthe amplifier’s bias circuitry. In addition, the LM4899 con-tains a Shutdown Mode pin, allowing the designer to desig-nate whether the part will be driven into shutdown with a highlevel logic signal or a low level logic signal. This allows thedesigner maximum flexibility in device use, as the ShutdownMode pin may simply be tied permanently to either VDD orGND to set the LM4899 as either a "shutdown-high" deviceor a "shutdown-low" device, respectively. The device maythen be placed into shutdown mode by toggling the Shut-down Select pin to the same state as the Shutdown Modepin. For simplicity’s sake, this is called "shutdown same", asthe LM4899 enters shutdown mode whenever the two pinsare in the same logic state. The trigger point for eithershutdown high or shutdown low is shown as a typical valuein the Supply Current vs Shutdown Voltage graphs in theTypical Performance Characteristics section. It is best toswitch between ground and supply for maximum perfor-mance. While the device may be disabled with shutdownvoltages in between ground and supply, the idle current maybe greater than the typical value of 0.1µA. In either case, theshutdown pin should be tied to a definite voltage to avoidunwanted state changes.

In many applications, a microcontroller or microprocessoroutput is used to control the shutdown circuitry, which pro-vides a quick, smooth transition to shutdown. Another solu-tion is to use a single-throw switch in conjunction with anexternal pull-up resistor (or pull-down, depending on shut-down high or low application). This scheme guarantees thatthe shutdown pin will not float, thus preventing unwantedstate changes.

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Physical Dimensions inches (millimeters)unless otherwise noted

9-Bump micro SMDOrder Number LM4899ITL

NS Package Number TLA09AAAX1 = 1.514±0.03 X2 = 1.514±0.03 X3 = 0.600±0.075

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

LLPOrder Number LM4899LD

NSPackage Number LDA10B

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

Mini Small Outline (MSOP)Order Number LM4899MM

NSPackage Number MUB10A

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORTDEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERALCOUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices orsystems which, (a) are intended for surgical implantinto the body, or (b) support or sustain life, andwhose failure to perform when properly used inaccordance with instructions for use provided in thelabeling, can be reasonably expected to result in asignificant injury to the user.

2. A critical component is any component of a lifesupport device or system whose failure to performcan be reasonably expected to cause the failure ofthe life support device or system, or to affect itssafety or effectiveness.

National SemiconductorAmericas CustomerSupport CenterEmail: [email protected]: 1-800-272-9959

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Fax: +49 (0) 180-530 85 86Email: [email protected]

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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.

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LM4899 Boomer ® Audio Power Amplifier Series 1 Watt Fully