MD4255

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierGeneral DescriptionThe MD4255 is a 15W(per channel) efficient, Class-D audio power amplifier for driving bridged-tied stereo speakers.Advanced EMI Suppression Technology enables the use of inexpensive ferrite bead filters at the outputs while meeting EMC requirements.SpeakerGuard speaker protection circuitry includes an adjustable power limiter and a DC detection circuit.The adjustable power limiter allows the user to set a “virtual” voltage rail lower than the chip supply to limit the amount of current through the speaker.The DC detect circuit measures the frequency and amplitude of the PWM signal and shuts off the output stage if the input capacitors are damaged or shorts exist on the inputs.The MD4255 can drive stereo speakers as low as 4W.The high efficiency of the MD4255,90%,eliminates the need for an external heat sink when playing music.The outputs are also fully protected against shorts to GND,Vcc,and output-to-output.The short-circuit protection and thermal protection includes an auto-recovery feature.Features15-W/ch into an 8-Ω Loads at 10% THD+NFrom a 16-V Supply10-W/ch into 8-Ω Loads at 10% THD+N From a13-V Supply30-W into a 4-Ω Mono Load at 10% THD+NFrom a 16-V Supply90% Efficient Class-D Operation EliminatesNeed for Heat SinksWide Supply Voltage Range Allows Operationfrom 8 V to 26 VFilter-Free OperationSpeakerGuard™ Speaker ProtectionIncludesAdjustable Power Limiter plus DC ProtectionFlow Through Pin Out Facilitates Easy BoardLayoutRobust Pin-to-Pin Short Circuit Protection andThermal Protection with Auto Recovery OptionExcellent THD+N / Pop-Free PerformanceFour Selectable, Fixed Gain SettingsDifferential InputsApplicationsTelevisionsConsumer Audio Equipment地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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1June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierFunction Block DiagramGVDDPVCCLPVCCLBSPLPBTL SelectGateDriveOUTPL FBOUTPL FBOUTPLLINPGainControlLINNPLIMITPWMLogicGVDDPVCCLPVCCLPGNDBSNLOUTNL FBFAULTGateDriveSDTTLBufferOUTPL FBOUTNLGAIN0GAIN1SC DelectGainControlRampGeneratorPGNDBiases andReferenceDC DelectStartup ProtectionLogicPLMITPLIMITReferenceThermalDelectUVLO/OVLO AVCCLDORegulatorAVDD GVDDPVCCLPVCCLBSNRGVDD GVDDOUTNN FBGateDriveOUTNROUTPL FBRINNGainControlRINPPLIMITPWMLogicPGNDGVDDPVCCLOUTNN FBPVCCLBSPRGateDrivePBTLTTLBufferPBTLSelectPBTLSelectOUTPL FBBSPR AGNDPGND地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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2June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierPin Configuration TSSOP_28L1 2 3 4 5 6 7 8 9 1011 1213142827262524232221201918171615Top View 3地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierPin DescriptionsPin #1 SymbolSDDescriptionShutdown signal for audio amp(low = outputs Hi-Z, high = outpus enabled).TTL logic levels with compliance to AVCC.Open drain output used to display short circuitor dc detect fault status.Voltage compliantto AVCC.Short circuit faults can be set to auto-recoveryby connecting FAULT pin to SD pin.Otherwise,both short circuit faults and dc detect faults must be reset by cycling PVCC.Positive audio input for left channel.Biased at 3V.Negative audio input for left channel.Biased at 3V.Gain select least significant bit.TTL logic levels with compliance to AVCC.Gain select most significant bit.TTL logic levels with compliance to AVCC.Analog supplyAnalog signal ground.Connect to the thermal pad.High-side FET gate drive supply.Nominal voltage is 7V.Also should be used as supply for PLIMIT function.Power limit level adjust.Connect a resistor divider from GVDD to GND to set power limit.Connect directly to GVDD for no power limit.Negative audio input for right channel.Biased at 3V.Positive audio input for right channel.Biased at 3V.Not connected Parallel BTL mode switchPower supply for right channel H-bridge.Right channel and left channel powersupply inputs are connect internally.Power supply for right channel H-bridge.Right channel and left channel powersupply inputs are connect internally.Bootstrap I/O for right channel,positive high-side FET.Class-D H-bridge positive output for right channel.Power ground for the H-bridges. Class-D H-bridge negative output for right channel. Bootstrap I/O for right channel,negative high-side FET. Bootstrap I/O for left channel,negative high-side FET. Class-D H-bridge negative output for left channel. Power ground for the H-bridges. Class-D H-bridge positive output for left channel. Bootstrap I/O for left channel,positive high-side FET. Power supply for left channel H-bridge.Right channel and left channel powersupply inputs are connect internally.Power supply for left channel H-bridge.Right channel and left channel powersupply inputs are connect internally.2 3 4 5 6 7 8 9 10111213141516171819202122232425262728FAULT LINPLINNGAIN0 GAIN1 AVCCAGNDGVDDPLIMITRINNRINPNCPBTLPVCCR PVCCR BSPROUTPR PGND OUTNR BSNRBSNLOUTNL PGNDOUTPL BSPLPVCCL PVCCL 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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4June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Application Circuit P V C C 1 0 0 m F 0 . 1 m F 1 0 0 0 p F C o n t r o l S y s te m 1 0 0 k W1 k W1 2 S D F A U L T L I N P L I N N G A I N0 G A I N1 A V C C A G N D P V C C P V C C B S N O U T N P G N D O U T N 2 8 2 7 2 6 2 5 1 0 0 0 p F 0 .2 2 m F 1 F 1 F 3 4 5 F B 2 4 2 3 2 2 0 . 2 2 m F 1 0 0 0 p F P V C C 6 1 0 W7 1 F MD4255B S N B S P O U T P P G N D O U T P B S P P V C C F B F B 1 0 0 0 p F 8 2 1 2 0 1 9 1 8 1 7 0 . 2 2 m F

A u d i o S o u r c e 1 F 1 F 1 0 k W1 F 9 G V D D 1 0 1 1 1 2 P L I M I T R I N N R I N P N C P B T L 1 0 k W1 0 0 0 p F F B 0 .2 2 m F 1 F 1 3 1 4 1 6 1 5 1 0 0 m F 0 . 1 m F 1 0 0 0 p F P V C C G N D 2 9 P o w e r PA D P V C C Figure1. StereoClass-D Amplifier withBTL Outputand Single-EndedInputs地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼

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5June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Application Circuit P V C C F 1 0 0 m 0 . 1 m F 1 00 0 p F 1 0 0 k WC o n t r o l S y s t e m 1 1 k WS D F A U LT L I N P L I N N G A I N0 G A I N1 A V C C A G N D P V C C P V C C B S N O U T N P G N D O U T N 2 8 2 7 2 6 0 . 4 7 m F 2 3 4 5 6 2 5 2 4 2 3 2 2 2 1 2 0 1 9 0 .4 7 m F 1 0 00 p F F B 1 00 0 p F P V C C 7 1 0 W1 F MD4255B S N B S P O U T P P G N D O U T P B S P P V C C 8 9 1 F 1 F G V D D 1 0 F B 1 1 1 2 1 3 1 4 P L I M I T R I N N R I N P N C P B T L G N D 1 8 1 7 1 6 1 5 1 0 0 m F 0 .1 m F 1 0 00 p F A u d io S o u r c e 1 F A V C C P V C C 2 9 P o w e r PA D P V C C Figure2. StereoClass-D Amplifier withPBTLOutputand Single-EndedInput 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼

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6June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierAbsolute Maximum Ratings1 SymbolDescription Value -0.3 to 30-0.3 to Vcc+0.3 UnitV V V °C°C°CV CCV IV INT J T SDRT STGSupply Voltage at no Input SignalLogic Input VoltageAnalog Input VoltageOperating Junction Temperature Range Maximum Lead Soldering Temperature , 10 Seconds Storage Temperature Range-0.3 to 7-40 to 150260 -65 to 150Recommended Operating ConditionsSymbolVccTATJDescription Supply VoltageAmbient Temperature RangeJunction Temperature RangeValue8~26-40~85-40~125UnitV°C°CThermal Information 2SymbolJADescription Thermal Resistance-Junction to AmbientValueUnit°C/WOrdering and Marking InformationDeviceMD3110Package Type TSSOP_28Device MarkingReel Size13’’Tape Width12mmQuantity3000 units.MD4255 XXXXX ESD SusceptibilityESD Susceptibility-HBM -------------------------------------------------------------------2kV ESD Susceptibility-MM -------------------------------------------------------------------200V 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device.Functional operation atconditions other than the operating conditions specified is not implied.Only one Absolute Maximum Rating should be applied atone time. 2. The ThermalPad on the bottom of the IC should soldered directly to the PCB’s ThermalPad area that with several thermal vias connect to the ground plan,and the PCB is a 2-layer,5-inch square area with 2oz copper thickness.地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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7June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierElectrical CharacteristicsDC CharacteristicsT C,V noted)A = 25° CC= 24V,R L = 8 W(unless otherwise PARAMETER TESTCONDITIONSMIN TYP MAX UNIT| V OS| I CCI CC(SD)r DS(on)Class-D outputoffsetvoltage (measured differentially) Quiescent supplycurrent Quiescent supplycurrent inshutdownmodeDrain-sourceon-stateresistanceV I = 0 V,Gain= 36dBSD= 2 V,noload, PVCC= 24V SD= 0.8 V,noload, PVCC= 24V V CC= 12V,I O = 500 mA, T = 25° C J GAIN1 = 0.8 V HighSideLow sideGAIN0 = 0.8 V GAIN0 = 2 V GAIN0 = 0.8 V GAIN0 = 2 V 192531351.5 32250 240 240 20263236142 6.4 6.9 420 1550400 mVmAµ A m W21273337dBdBmss G GainGAIN1 = 2 V t ont OFF GVDDt DCDET Turn-on timeTurn-offtimeGateDrive SupplyDCDetecttimeSD= 2 V SD= 0.8 V I GVDD= 100 A V (RINN)= 6V, VRINP = 0V7.4 V msDC CharacteristicsT C,V noted)A = 25° CC= 12V,R L = 8 W(unless otherwise PARAMETER TESTCONDITIONSMIN TYP MAX UNIT I CC| V OS| Class-D outputoffsetvoltage (measured differentially) V = 0 V,Gain= 36dB I HighSideLow sideGAIN0 = 0.8 V GAIN0 = 2 V GAIN0 = 0.8 V GAIN0 = 2 V 192531351.5 20200 240 240 20263236142 6.4 6.756.9 7.901535mVmAµ A m WQuiescent supplycurrent Quiescent supplycurrent inshutdownmodeSD= 2 V,noload, PVCC= 12V I CC(SD)r DS(on) Drain-sourceon-stateresistance V SD= 0.8 V,noload, PVCC= 12V = 12V,I O = 500 mA, T C J = 25° CCGAIN1 = 0.8 V G GainGAIN1 = 2 V t ONt OFF GVDDV O Turn-on timeTurn-offtimeGateDrive SupplyOutputVoltage maximum under PLIMITcontrol SD= 2 V SD= 0.8 V I GVDD= 2mA V (PLIMIT)= 2 V;V I = 1Vrms 21273337dBdBmss 7.4 8.75V V 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼

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8June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierElectrical CharacteristicsAC CharacteristicsT C,V noted)A = 25° CC= 24V,R L = 8 W(unless otherwise PARAMETER TESTCONDITIONSMIN TYP MAX UNITK SVR P O Power Supplyripplerejection Continuousoutputpower 200 mVPPrippleat1 kHz,Gain= 20dB, Inputsac-coupledtoAGNDTHD+N = 10%,f = 1 kHz,V CC= 16V V CC= 16V,f = 1 kHz,P O = 7.5 W (half-power)20Hzto22kHz,A-weightedfilter, Gain= 20dBV O = 1 Vrms, Gain= 20dB, f = 1 kHz Maximum outputatTHD+N < 1%, f = 1 kHz,Gain= 20dB, A-weighted250 - 70150.1 65- 80- 100 102 310 150 15350 dBW % µ V dBV dBdBkHz ° C ° C THD+N Total harmonicdistortion+ noise V n Outputintegratednoise Crosstalk SNR f OSC Signal-to-noise ratio Oscillatorfrequency Thermal trippoint Thermal hysteresisAC CharacteristicsT C,V noted)A = 25° CC= 12V,R L = 8 W(unless otherwise PARAMETER TESTCONDITIONSMIN TYP MAX UNITK SVR P O Supplyripplerejection Continuousoutputpower 200 mVPPripplefrom20Hz- 1 kHz,Gain= 20dB, Inputsac-coupledtoAGNDTHD+N = 10%,f = 1 kHz;V CC= 13V - 70100.0665- 80- 100 102 250 310 150 15350 dBW % µ V dBV dBdBkHz ° C ° C THD+N Total harmonicdistortion+ noise V n Outputintegratednoise Crosstalk SNR f OSC Signal-to-noise ratio Oscillatorfrequency Thermal trippoint Thermal hysteresisR L = 8 W, f = 1 kHz,P O = 5 W (half-power)20Hzto22kHz,A-weightedfilter, Gain= 20dBP o = 1 W,Gain= 20dB, f = 1 kHz Maximum outputatTHD+N < 1%, f = 1 kHz,Gain= 20dB, A-weighted 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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9June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsTOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) TOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) 10Gain = 20 dBV C C = 12 V Z = 8 + 66 H L 1 10Gain = 20 dBV C C = 18 V Z = 8 + 66 H L 1 THD-TotalHarmonicDistortion-% 0.1 P = 5 WO THD-TotalHarmonicDistortion-% 0.1 P = 10 W O P = 1 WO 0.01P = 0.5 WO P = 2.5 WO 0.01P = 5 WO 0.001 200.001 20100 1kf - Frequency - HzFigure3.10k 20k 100 1kf - Frequency - HzFigure4.10k 20k TOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) TOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) 10Gain = 20 dBV = 24 V C C Z = 8 + 66 H L 1 10Gain = 20 dBV C C = 12 V Z = 6 + 47 H L 1 THD-TotalHarmonicDistortion-%0.1 P = 10 W O THD-TotalHarmonicDistortion-%0.1 P = 5 WO P = 1 WO 0.010.01P = 0.5 WO P = 2.5 WO

P = 5 WO 0.001 20100 1kf - Frequency - HzFigure5.10k 20k 0.001 20100 1kf - Frequency - HzFigure6.10k 20k TOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) TOTAL HARMONICDISTORTIONvsFREQUENCY (BTL) 10Gain = 20 dBV = 18 V C C Z = 6 + 47 H L 1 10Gain = 20 dBV C C = 12 V Z = 4 + 33 H L 1 THD-TotalHarmonicDistortion-%0.1 P = 10 W O THD-TotalHarmonicDistortion-%0.1 P = 10 W O P = 1 WO 0.01P = 1 WO P = 5 WO 100 1kf - Frequency - HzFigure7.0.01P = 5 WO 0.001 20 0.001 20

1k10k 20k 10k 20k 100 f - Frequency - HzFigure8.地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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10

June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsTOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) THD+N-TotalHarmonicDistortion+Noise-%Gain = 20 dBV C C = 12 V Z = 8 + 66 H L 1 THD+N-TotalHarmonicDistortion+Noise-%1010Gain = 20 dBV C C = 18 V Z = 8 + 66 H L 1 f = 20 Hz 0.1 f = 1 kHz f = 1 kHz 0.1 f = 20 Hz 0.010.01f = 10 kHz0.001 0.010.1 1 1050f = 10 kHz0.001 0.010.1 1 1050P - Output Power - W O Figure9.TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) P - Output Power - W O Figure10.TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) THD+N-TotalHarmonicDistortion+Noise-%10Gain = 20 dBV = 24 V C C Z = 8 + 66 H L 1 THD+N-TotalHarmonicDistortion+Noise-%10Gain = 20 dBV C C = 12 V Z = 6 + 47 H L 1 0.1 f = 1 kHz 0.1 f = 20 Hz f = 1 kHz 0.001 0.010.010.01f = 20 Hz f = 10 kHz0.1 1 1050f = 10 kHz0.001 0.010.1 1 P - Output Power - W O Figure12. TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) 1050P - Output Power - W O Figure11. TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (BTL) THD+N-TotalHarmonicDistortion+Noise-%Gain = 20 dBV C C = 18 V Z = 6 + 47 H L 1 f = 1 kHz 0.1 f = 20 Hz THD+N-TotalHarmonicDistortion+Noise-%1010Gain = 20 dBV C C = 12 V Z = 4 + 33 H L 1 f = 1 kHz 0.1 0.010.01f = 20 Hz f = 10 kHz0.001 0.010.1 1 1050f = 10 kHz0.001 0.010.1 1 1050P - Output Power - W O Figure13. P - Output Power - W O Figure14. 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼

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11June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsMAXIMUM OUTPUTPOWER vsPLIMITVOLTAGE (BTL) OUTPUTPOWER vsPLIMITVOLTAGE (BTL) 161412108 6 4 2 0 0.0 PO-OutputPower-WGain = 20 dBV = 24 V C C Z = 8 + 66 H L 3530252015105 0 0.5 1.0 1.5 2.0 2.5 3.0 0 1 2 3 4 5 6 V oltage - VP L I MI T - PLIMIT V Figure15. GAIN/PHASEvsFREQUENCY (BTL) PO(Max)-MaximumOutputPower-WGain = 20 dBV C C = 12 V Z = 4 + 33 H L V P L I M I T - PLIMIT V oltage - VFigure16. OUTPUTPOWER vsSUPPLYVOLTAGE (BTL) 4035Phase 3025 100 500 Phase-PO-OutputPower-W30Gain = 20 dBZ = 8 + 66 H L 25 20THD = 10% 15THD = 1%10-50 Gain-100-150C = 1 F I Gain = 20 dBFilter = Audio Precision AUX-0025 V = 12 V C C V = 0.1 Vrms I Z = 8 + 66 H L 100 1kf - Frequency - Hz10k -200Gain-dB2015105 0 205 -250-300100k0 6 8 101214161820222426V - Supply V oltage - VC C Figure17. Figure18. OUTPUTPOWER vsSUPPLYVOLTAGE (BTL) EFFICIENCYvsOUTPUTPOWER (BTL) 25Gain = 20 dBZ = 4 + 33 H L 20PO-OutputPower-W100 908070V = 12 V C C V C C = 18 V V C C = 24 V 15-Efficiency-%THD = 10% 60504030THD = 1%105 20 0 6 8 10121416V - Supply V oltage - VC C Note: DashedLines represent thermally limited regions.Figure19. 18 0 0 5 10152010Gain = 20 dBZ = 8 + 66 H L 30253540 12P - Output Power - W O Note: DashedLines represent thermally limited regions.Figure20. 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsEFFICIENCYvsOUTPUTPOWER (BTLwithLCFILTER) EFFICIENCYvsOUTPUTPOWER (BTL) 100 908070-Efficiency-%6050403020100 0 5 10152025P - Output Power - W O Figure21. Gain = 20 dBLC Filter = 22 H + 0.68 F R = 8 L V C C = 24 V -Efficiency-%V = 12 V C C V = 18 V C C 100 9080706050403020100 0 5 10152025P - Output Power - W O Figure22. V C C = 12 V V = 18 V C C Gain = 20 dBZ = 6 + 47 H L EFFICIENCYvsOUTPUTPOWER (BTLwithLCFILTER) EFFICIENCYvsOUTPUTPOWER (BTL) 100 908070-Efficiency-%6050V C C = 18 V -Efficiency-%V C C = 12 V 100 90V C C = 12 V 80706050403020100 0 5 101520250 3 6 9 121518P - Output Power - W O Figure23. 3020100 40 Gain = 20 dBLC Filter = 22 H + 0.68 F R = 6 L Gain = 20 dBZ = 4 + 33 H L P - Output Power - W O Figure24. EFFICIENCYvsOUTPUTPOWER (BTLwithLCFILTER) . SUPPLYCURRENT vsTOTAL OUTPUTPOWER (BTL) 100 908070-Efficiency-%6050403020100 0 5 10152025P - Output Power - W O Figure25. 2.6 2.4 V = 12 V C C ICC-SupplyCurrent-A2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 Gain = 20 dBLC Filter = 22 H + 0.68 F R = 4 L 0.4 0.2 0.0 0 5 10152025303540P - Total Output Power - W O ( To t ) Figure26. V C C = 18 V V C C = 12 V V C C = 24 V Gain = 20 dBZ = 8 + 66 H L 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼

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13

June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsSUPPLYCURRENT vsTOTAL OUTPUTPOWER (BTL) CROSSTALK vsFREQUENCY (BTL) 3.2 2.8 2.4 Crosstalk-dB2.0 V C C = 12 V 1.6 1.2 0.8 0.4 0.0 0 5 1015202530P - Total Output Power - W O ( To t ) Figure27. Gain = 20 dBZ = 4 + 33 H L -20 -30 -40 Gain = 20 dBV C C = 12 V V = 1 Vrms O Z = 8 + 66 H L ICC-SupplyCurrent-A-50 -60 -70 -80 -90 -100-110-120-13020100 1kf - Frequency - Hz10k 20k Left to Right Right to Left 0 KSVR-SupplyRippleRejectionRatio-dBSUPPLYRIPPLEREJECTION RATIO vsFREQUENCY (BTL) THD-TotalHarmonicDistortion-%10Figure28. TOTAL HARMONICDISTORTIONvsFREQUENCY (PBTL) -20 Gain = 20 dBV = 200 mV r i p p l e p p Z = 8 + 66 H L Gain = 20 dBV C C = 24 V Z = 4 + 33 H L 1 P = 5 WO -40 -60 V C C = 12 V 0.1 P = 0.5 WO 0.01P = 2.5 WO -80 -100-12020100 1kf - Frequency - HzFigure29. 10k 20k 0.001 20100 1kf - Frequency - HzFigure30. 10k 20k TOTAL HARMONICDISTORTION+ NOISE vsOUTPUTPOWER (PBTL)THD+N-TotalHarmonicDistortion+Noise-%10Gain = 20 dBV = 24 V C C Z = 4 + 33 H L 1 f = 1 kHz GAIN/PHASEvsFREQUENCY (PBTL)4035Phase 3025Gain-dB0 -50 Gain-100-150C = 1 F I Gain = 20 dBFilter = Audio Precision AUX-0025 V = 24 V C C V = 0.1 Vrms I Z = 8 + 66 H L 100 1kf - Frequency - Hz10k -200-250-300100k100 500.1 20150.01f = 20 Hz f = 10 kHz0.001 0.010.1 1 1050105 0 20P - Output Power - W O Figure31. Figure32. 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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14

G027

June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierTypical Performance CharacteristicsOUTPUTPOWER vsSUPPLYVOLTAGE (PBTL)EFFICIENCYvsOUTPUTPOWER (PBTL) 403530PO-OutputPower-W100 Gain = 20 dBZ = 4 + 33 H L 908070V C C = 18 V V = 12 V C C 25THD = 10% 201510THD = 1%-Efficiency-%60504030205 0 6 8 101214161820V oltage - VC C - Supply V Figure33. 100 0 5 10152025Gain = 20 dBZ = 4 + 33 H L 30354045P - Output Power - W O Figure34. SUPPLYCURRENT vsOUTPUTPOWER (PBTL)SUPPLYRIPPLEREJECTION RATIO vsFREQUENCY (PBTL)2.8 2.4 2.2 ICC-SupplyCurrent-A2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 0 5 1015202530P - Output Power - W O Figure35. 0 KSVR-SupplyRippleRejectionRatio-dBGain = 20 dBZ = 4 + 33 H L Gain = 20 dBV = 200 mV r i p p l e p p Z = 8 + 66 H L 2.6 -20 -40 V C C = 12 V V = 18 V C C -60 V C C = 12 V -80 -10035 4045 -12020100 1k10k 20k f - Frequency - HzFigure36. 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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15June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierApplication InformationGain setting via GAIN0 and GAIN1 inputsThe gain of the MD4255 is set by two input terminals,GAIN0 and GAIN1.The gains listed in Table 1 are realized by changing the taps on the input resistors and feedback resistors inside the amplifier. This causes the input impedance (Zi) to be dependent on the gain setting. The actual gain settings are controlled by ratios of resistors, so the gain variation from part-to-part is small. However, the input impedance from part-to-part at the same gain may shift by ±20% due to shifts in the actual For design purposes, the input network (discussed in the next section) should be designed assuming an input impedance of 7.2 kΩ, which is the absolute minimum input impedance of the MD3110. At the lower gainsettings, the input impedance could increase as high as 72 kΩ.Table 1 Gain SettingInput ImpedanceAmplifierGain (dB)(kΩ)G1G0TYPTYP00206002630132015136911The PLIMIT circuit sets a limit on the output peak-to-peak voltage. The limiting is done by limiting the duty cycle to fixed maximum value. This limit can be thought of as a \"virtual\" voltage rail which is lower than the supply connected to PVCC. This \"virtual\" rail is 4 times the voltage at the PLIMIT pin. This output voltage can be used to calculate the maximum output power for a given maximum input voltage and speaker impedance.R L 2 P O U T = R L + 2 x R S 2 x R L x V P for unclipped powerWhere:RS is the total series resistance including RDS(on)And any resistance in the output filter.RL is the load resistance.VP is the peak amplitude of the output possible VP = 4 × PLIMIT voltage if PLIMIT < 4 × VPPOUT (10%THD) = 1.25 × POUT (unclipped)Table 2. PLIMIT Typical OperationTestConditions()PLIMITOutputOutputVoltage Voltage Power (W) Amplitude (VP-P ) PVCC=24V, Vin=1Vrms,RL=8W, Gain=26dB PVCC=24V, Vin=1Vrms,RL=8W, Gain=26dB PVCC=24V, Vin=1Vrms,RL=8W, Gain=26dB PVCC=24V, Vin=1Vrms,RL=8W, Gain=26dB 6.972.9436.1(thermallylimited)15105 12.1105 10.55 5 4325.2SHUTDOWN OperationThe MD4255 employs a shutdown mode of operation designed to reduce supply current (ICC) to the absolute minimum level during periods of nonuse for power conservation. The SD input terminal should be held high (seespecification table for trip point) during normal operation when the amplifier is in use. Pulling SD low causes the outputs to mute and the amplifier to enter a low-current state. Never leave SD unconnected, because amplifier operation would be unpredictable.For the best power-off pop performance, place the amplifier in the shutdown mode prior to removing the power supply voltage. 2.34 1.62 6.973.001.866.971.76 201427.72314.823.515 PVCC=24V, Vin=1Vrms,RL=8W, Gain=20dB PVCC=24V, Vin=1Vrms,RL=8W, Gain=20dB PVCC=24V, Vin=1Vrms,RL=8W, Gain=20dB PVCC=12V, Vin=1Vrms,RL=8W, Gain=20dB PVCC=12V, Vin=1Vrms,RL=8W, Gain=20dB PLIMITThe voltage at pin 10 can used to limit the power to levels below that which is possible based on the supply rail.Add a resistor divider from GVDD to ground to set the voltage at the PLIMIT pin. An external reference may also be used if tighter tolerance is required. Also add a 1mF capacitor from pin 10 to ground.GVDD SupplyThe GVDD Supply is used to power the gates of the output full bridge transistors. It can also be used to supply the PLIMIT voltage divider circuit. Add a 1mF capacitor to ground at this pin.地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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16June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierDC DetectMD4255 has circuitry which will protect the speakers from DC current which might occur due to defective capacitors on the input or shorts on the printed circuit board at the inputs. A DC detect fault will be reported on the FAULT pin as a low state. The DC Detect fault will also cause the amplifier to shutdown by changing the state of the outputs to Hi-Z. To clear the DC Detect it is necessary to cycle the PVCC supply. Cycling SD will NOT clear a DC detect fault.A DC Detect Fault is issued when the output differential duty-cycle of either channel exceeds 14% (for example,+57%, -43%) for more than 420 msec at the same polarity. This feature protects the speaker from large DC currents or AC currents less than 2Hz. To avoid nuisance faults due to the DC detect circuit, hold the SD pin low at power-up until the signals at the inputs are stable. Also, take care to match the impedance seen at the positive and negative inputs to avoid nuisance DC detect faults.The minimum differential input voltages required to trigger the DC detect are show in table 2. The inputs must remain at or above the voltage listed in the table for more than 420 msec to trigger the DC detect.Table 3. DC Detect ThresholdAV(dB)Vin (mV,differential) Short-Circuit Protection and Automatic Recovery FeatureMD4255 has protection from overcurrent conditions caused by a short circuit on the output stage. The short circuit protection fault is reported on the FAULT pin as a low state. The amplifier outputs are switched to a Hi-Z state when the short circuit protection latch is engaged. The latch can be cleared by cycling the SD pin through the low state.If automatic recovery from the short circuit protection latch is desired, connect the FAULT pin directly to the SD pin. This allows the FAULT pin function to automatically drive the SD pin low which clears the short-circuit protection latch.Thermal ProtectiomThermal protection on the MD4255 prevents damage to the device when the internal die temperature exceeds 150°C. There is a ±15°C tolerance on this trip point from device to device. Once the die temperature exceeds the thermal set point, the device enters into the shutdown state and the outputs are disabled. This is nota latched fault. The thermal fault is cleared once the temperature of the die is reduced by 15°C. The device begins normal operation at this point with no external system interaction.Thermal protection faults are NOT reported on the FAULT terminal.MD3110 Modulation SchemeThe MD4255 uses a modulation scheme that allows operation without the classic LC reconstruction filter when the amp is driving an inductive load. Each output is switching from 0 volts to the supply voltage. The OUTP and OUTN are in phase with each other with no input so that there is little or no current in the speaker. The duty cycle of OUTP is greater than 50% and OUTN is less than 50% for positive output voltages. The duty cycle of OUTP is less than 50% and OUTN is greater than 50% for negative output voltages. The voltage across the loadsits at 0V throughout most of the switching period, greatly reducing the switching current, which reduces any I2R losses in the load.20263236112 562817PBTL SelectMD4255 offers the feature of parallel BTL operation with two outputs of each channel connected directly. If the PBTL pin (pin 14) is tied high, the positive and negative outputs of each channel (left and right) are synchronized and in phase. To operate in this PBTL (mono) mode, apply the input signal to the RIGHT input andplace the speaker between the LEFT and RIGHT outputs. Connect the positive and negative output together for best efficiency. For an example of the PBTL connection, see the schematic in the application information section.For normal BTL operation, connect the PBTL pin to local ground.地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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17June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierOUTPOUTN0VOUTPOUTP-OUTN Speaker Current OUTPOUTNPVCCOUTP-OUTN 0VSpeaker Current 0APositive Output No Output OUTPOUTNOUTP- OUTN0V-PVCC 0ASpeaker Current . Negative Output Figure 37. The MD4255 Output Voltage and Current Waveforms Into an Inductive Load Ferrite Bead Filter Considerations Using the Advanced Emissions Suppression Technology in the MD4255 amplifier it is possible to design a high efficiency Class-D audio amplifier while minimizing interference to surrounding circuits. It is also possible toaccomplish this with only a low-cost ferrite bead filter. In this case it is necessary to carefully select the ferrite bead used in the filter.One important aspect of the ferrite bead selection is the type of material used in the ferrite bead. Not all ferrite material is alike, so it is important to select a material that is effective in the 10 to 100 MHz range which is key tothe operation of the Class D amplifier. Many of the specifications regulating consumer electronics have emissions limits as low as 30 MHz. It is important to use the ferrite bead filter to block radiation in the 30 MHZ and above range from appearing on the speaker wires and the power supply lines which are good antennas forthese signals. The impedance of the ferrite bead can be used along with a small capacitor with a value in the range of 1000 pF to reduce the frequency spectrum of the signal to an acceptable level. For best performance,the resonant frequency of the ferrite bead/ capacitor filter should be less than 10 MHz.Also, it is important that the ferrite bead is large enough to maintain its impedance at the peak currents expected for the amplifier. Some ferrite bead manufacturers specify the bead impedance at a variety of current levels. In this case it is possible to make sure the ferrite bead maintains an adequate amount of impedance at the peakcurrent the amplifier will see. If these specifications are not available, it is also possible to estimate the bead current handling capability by measuring the resonant frequency of the filter output at very low power and atmaximum power. A change of resonant frequency of less than fifty percent under this condition is desirable.Examples of ferrite beads which have been tested and work well with the MD4255 include 28L0138-80R-10 and HI1812V101R-10 from Steward and the 742792510 from Wurth Electronics.A high quality ceramic capacitor is also needed for the ferrite bead filter. A low ESR capacitor with good temperature and voltage characteristics will work best.Additional EMC improvements may be obtained by adding snubber networks from each of the class D outputs to ground. Suggested values for a simple RC series snubber network would be 10Ω in series with a 330 pF capacitor although design of the snubber network is specific to every application and must be designed takinginto account the parasitic reactance of the printed circuit board as well as the audio amp. Take care to evaluate the stress on the component in the snubber network especially if the amp is running at high PVCC. Also, makesure the layout of the snubber network is tight and returns directly to the PGND or the PowerPad™ beneath the chip.706050403020100 30M FCC Class B 230M430M630M 830Mf - Frequency - HzFigure 38.MD4255 EMC spectrum with FCC Class B LimitsEfficiency: LC Filter Required With the Traditional Class-D Modulation SchemeThe main reason that the traditional class-D amplifier needs an output filter is that the switching waveform results in maximum current flow. This causes more loss in the load, which causes lower efficiency. The ripple current islarge for the traditional modulation scheme, because the ripple current is proportional to 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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18

June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio Amplifierbecause the ripple current is proportional to voltage multiplied by the time at that voltage. The differential voltage swing is 2 × VCC, and the time at each voltage is half the period for the traditional modulation scheme. An ideal LC filter is needed to store the ripple current from each half cycle for the next half cycle, while any resistance causes power dissipation. The speaker is both resistive and reactive,whereas an LC filter is almost purely reactive.The MD4255 modulation scheme has little loss in the load without a filter because the pulses are short and the change in voltage is VCC instead of 2 × VCC. As the output power increases, the pulses widen, making the ripple current larger. Ripple current could be filtered with an LC filter for increased efficiency, but for most applications the filter is not needed.An LC filter with a cutoff frequency less than the class-D switching frequency allows the switching current to flow through the filter instead of the load. The filter has less resistance but higher impedance at the switching frequency than the speaker, which results in less power dissipation, therefore increasing efficiency.OUTP33uHL133uHL2●C2●1uFOUTNC31uFFigure 39. Typical LC Output Filter, Cutoff Frequency of 27 kHz, Speaker Impedance = 8 ΩOUTP15uHL115uHL2●C2●2.2uFOUTNC32.2uFFigure 40. Typical LC Output Filter, Cutoff Frequency of 27 kHz, Speaker Impedance = 4 ΩFerriteChip BeadOUTPFerriteChip Bead●1nFOUTN●When to Use an Output Filter for EMI SuppressionThe MD4255 has been tested with a simple ferrite bead filter for a variety of applications including long speaker wires up to 125 cm and high power. The MD4255 EVM passes FCC Class B specifications under these conditions using twisted speaker wires. The size and type of ferrite bead can be selected to meet application requirements. Also, the filter capacitor can be increased if necessary with some impact on efficiency.There may be a few circuit instances where it is necessary to add a complete LC reconstruction filter. These circumstances might occur if there are nearby circuits which are very sensitive to noise. In these cases a classic second order Butterworth filter similar to those shown in the figures below can be used.Some systems have little power supply decoupling from the AC line but are also subject to line conducted interference (LCI) regulations. These include systems powered by \"wall warts\" and \"power bricks.\" In these cases, it LC reconstruction filters can be the lowest cost means to pass LCI tests. Common mode chokes using low frequency ferrite material can also be effective at preventing line conducted interference.1nFFigure 41. Typical Ferrite Chip Bead Filter (Chip Bead Example: ) CopyrightInput ResistanceChanging the gain setting can vary the input resistance of the amplifier from its smallest value, 9 kΩ±20% largest value, 60 kΩ± 20%As a result, if a single capacitor is used in the input high-pass filter, the -3dB or cutoff frequency may change when changing gain steps.ZfCiInputSignalINZiThe -3dB frequency can be calculated using Equation 2. Use the Zi values given in Table 1.f =1 2 Z i C i Input Capacitor, CIIn the typical application, an input capacitor (Ci) is required to allow the amplifier to bias the input signal to the proper dc level for optimum 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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19June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio Amplifierimpedance of the amplifier (Zi) form a high-pass filter with the corner frequency determined in Equation 3.-3dBfcf c = 1 2 Z i C i The value of Ci is important, as it directly affects the bass (low-frequency) performance of the circuit. Consider the example where Zi is 60 kΩ and the specification calls for a flat bass response down to 20 Hz. Equation 3 isC i = 1 2 Z i f c In this example, Ci is 0.13 μF; so, one would likely choose a value of 0.15 mF as this value is commonly used. If the gain is known and is constant, use Zi from Table 1 to calculate C. iA further consideration for this capacitor is the leakage path from the input source through the input network (Ci) and the feedback network to the load. This leakage current creates a dc offset voltage at the input to the amplifier that reduces useful headroom, especially in high gain applications. For this reason, a low-leakage tantalum or ceramic capacitor is the best choice. When polarized capacitors are used, the positive side of the capacitor should face the amplifier input in most applications as the dc level there is held at 3 V, which is likely higher than the source dc level. Note that it is important to confirm the capacitor polarity in the application. Additionally, lead-free solder can create dc offset voltages and it is important to ensure that boards are as bond wire and copper trace inductances as well as lead frame capacitance, a good quality low equivalent-series-resistance (ESR)ceramic capacitor of value between 220 pF and 1000 pF works well. This capacitor should be placed as close to the device PVCC pins and system ground (either PGND pins or PowerPad) as possible. For mid-frequency noise due to filter resonances or PWM switching transients as well as digital hash on the line, another good qualitycapacitor typically 0.1 mF to 1 μF placed as close as possible to the device PVCC leads works best For filtering lower frequency noise signals, a larger aluminum electrolytic capacitor of 220 mF or greater placed near the audio power amplifier is recommended. The 220 mF capacitor also serves as a local storage capacitor for supplying current during large signal transients on the amplifier outputs. The PVCC terminals provide the power to the output transistors, so a 220 μF or larger capacitor should be placed on each PVCC terminal. A 10 μF capacitor on the AVCC terminal is adequate. Also, a small decoupling resistor between AVCC and PVCC can be used to keep high frequency class D noise from entering the linear input amplifiers.BSN and BSP CapacitorsThe full H-bridge output stages use only NMOS transistors. Therefore, they require bootstrap capacitors for the high side of each output to turn on correctly. A 0.22 mF ceramic capacitor, rated for at least 25 V, must be connected from each output to its corresponding bootstrap input. Specifically, one 0.22 mF capacitor must beconnected from OUTPx to BSPx, and one 0.22 mF capacitor must be connected from OUTNx to BSNx. (See the application circuit diagram in Figure 1.)The bootstrap capacitors connected between the BSxx pins and corresponding output function as a floating power supply for the high-side N-channel power MOSFET gate drive circuitry. During each high-side switching cycle, the bootstrap capacitors hold the gate-to-source voltage high enough to keep the high-side MOSFETs turned on.Power Supply Decoupling, CSThe MD4255 is a high-performance CMOS audio amplifier that requires adequate power supply decoupling to ensure that the output total harmonic distortion (THD) is as low as possible. Power supply decoupling also prevents oscillations for long lead lengths between the amplifier and the speaker. Optimum decoupling is achieved by using a network of capacitors of different types that target specific types of noise on the power supply leads. For higher frequency transients due to parasitic circuit elements such Differential InputsThe differential input stage of the amplifier cancels any noise that appears on both input lines of the channel. To use the MD4255with a differential source, connect the positive lead of the audio source to the INP input and the negative lead from the audio source to the INN input. To use the MD4255with a single-ended source, ac ground the INP or INN input through a capacitor equal in value to the input capacitor on 地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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20June,2010 Rev.1.0

深圳市瑞信集成电路有限公司Shenzhen Megapower Integrated Circuit Co.,ltdMD425515W Stereo Class D Audio AmplifierINN or INP and apply the audio source to either input. In a single-ended input application, the unused input should be ac grounded at the audio source instead of at the device input for best noise performance. For good transient performance, the impedance seen at each of the two differential inputs should be the same.The impedance seen at the inputs should be limited to an RC time constant of 1 ms or less if possible. This is to allow the input dc blocking capacitors to become completely charged during the 14 ms power-up time. If the input capacitors are not allowed to completely charge, there will be some additional sensitivity to component matching which can result in pop if the input components are not well matched.Using Low-ESR CapacitorsLow-ESR capacitors are recommended throughout this application section. A real (as opposed to ideal) capacitor can be modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistorminimizes the beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance,the more the real capacitor behaves like an ideal capacitor.地址:深圳市龙华民治大道2号华通源物流中心A5栋北座5楼网址:www.megapower.com.cn

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21June,2010 Rev.1.0