MAXIM MAX9703/MAX9704 handbook
Contents
1. TOTAL HARMONIC DISTORTION PLUS TOTAL HARMONIC DISTORTION PLUS TOTAL HARMONIC DISTORTION PLUS NOISE vs FREQUENCY NOISE vs FREQUENCY NOISE vs FREQUENCY 10 10 8 1 1 a e E E 0 1 0 1 0 01 0 01 10 100 1 10k 100k 10 100 1 10k 100k Ok FREQUENCY Hz FREQUENCY Hz FREQUENCY Hz TOTAL HARMONIC DISTORTION PLUS TOTAL HARMONIC DISTORTION PLUS TOTAL HARMONIC DISTORTION PLUS NOISE vs FREQUENCY NOISE vs OUTPUT POWER NOISE vs OUTPUT POWER 10 A 100 2 10 Vpp 20V 8 Vpp 15V E Vpp 15V E 8Q 4Q 5 RL 8Q 8 Ay 16dB Ay 1698 Ay 1648 3 Pour 8W 10 1 1 10kHz g SS f 10kHz E X 1 ES f 1kHz 0 1 0 1 i 04 FF S f 100Hz f 100Hz 0 01 0 01 0 01 10 00 1k 10k 100k 0 23 4 5 6 7 8 9 10 01234567 8 9 1011 1213 14 15 FREQUENCY Hz OUTPUT POWER W OUTPUT POWER W TOTAL HARMONIC DISTORTION PLUS TOTAL HARMONIC DISTORTION PLUS NOISE vs OUTPUT POWER NOISE vs OUTPUT POWER EFFICIENCY vs OUTPUT POWER 10 10 Vpp 20V _ 8 E 8Q 90 8Q Ay 1608 3 8 2 f 1kHz 1 7 SSM 62. REV 70 44 27 SEN mr um max wax 1577 5 4551420 45 455 4701485 4 075 o7 25 so 028 os ers E emen em em pen e o oos mems f a8 0 es aie uses faofa jun 48 lalala il o m EJ Ex fz ozs Jos jam oz a oka e ess oso oe ose oss 030 oo oso aas ose ons osa 75 75 177156 2 u a 4 s ee 50 5 60 540 5 50 seo se ss sm se sm aaa rme7 2 540 550 5 60 540 5501580 NOTE 4877 1 IS A CUSTOM 48L PKG WITH 4 LEADS DEPOPULATED TOTAL NUMBER OF LEADS ARE 44 1 DIMENSIONING amp TOLERANCING CONFORM TO ASME Y14 5M 1994 2 ALL DIMENSIONS ARE IN MILUMETERS ANGLES ARE IN DEGREES 3 N IS THE TOTAL NUMBER OF TERMINALS THE TERMINAL 1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95 1 5 012 DETAILS OF TERMINAL 1 IDENTIFIER ARE OPTIONAL BUT MUST BE LOCATED WITHIN THE ZONE INDICATED THE TERMINAL 1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE DIMENSION b APPUES TO METALLIZED Me AND IS MEASURED BETWEEN 0 25 mm AND 0 30 mm FROM TERM TIP ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND
3. MAXIM 1 MAXIM MAX9703 1 MAX9704 21314519 5 3114115116 mU Ge gt gt c 7 g 2 oz 5 in d i c TQFN 5mm 5mm TQFN 7mm x 7mm Chip Information MAX9703 TRANSISTOR COUNT 3093 MAX9704 TRANSISTOR COUNT 4630 PROCESS BiCMOS P0Z6XVW E0Z6XVIMW 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers OC Package Information The package drawing s in this data sheet may not reflect the most current specifications For the latest package outline information go to www maxim ic com packages DETAIL A NE 1 X E 32 44 48L QFN EPS MAX9703 MAX9704 R IS OPTIONAL te TERMINAL eer DALLAS VIAXAL VI me PACKAGE OUTLINE 32 44 48 56L THIN QFN 7x7x0 8mm WAARD COSNROL IO REL 1 18 MAKLM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Package Information continued The package drawing s in this data sheet may not reflect the most current specifications For the latest package outline information go to www maxim ic com packages 6 0 7 00 7 10 6 90 7 0 7 10 690 7 00 7 10 6 90 720 7 10 6 90 700 7 10 60 7 00 7 10 6 90 7 00 1o 6 90 00 7 10 680 7 00 17 10 60 700 14877 5 0 50 BSC BSE ne 0 65 BSC COMMON DIMENSIONS EXPOSED PAD VARIATIONS CUSTOM 1 DEPOPULK oaz utc T4877 1 cope
4. FS2 PGND fs 660kHz RL connected between OUTL and OUTL and OUTR and OUTR Ta TMIN to Tmax unless otherwise noted Typical values are at Ta 25 C Notes 1 2 PARAMETER SYMBOL CONDITIONS MIN TYP MAX THD N 10 Vpp 40 10 Continuous Output Power 16V f 1kHz Ta 2 PCONT 80 MAX9703 25 C tcont 15min Note 4 160 Vpp 24V THD N 10 Continuous Output Power 16V f 1kHz Ta 80 MAX9704 25 15min Note 4 16Q Vpp 24V Total Harmonic Distortion Plus 1kHz either FFM or SSM RL 80 Noise Pour 4W BW 22Hz to RL 8Q Pout 22kHz 10W f 1kHz Signal to Noise Ratio A weighted Crosstalk Left to right right to left 80 load fin 10kHz FS12L FS22L FS1 L FS2 H Oscillator Frequency FS1 H FS2 L FS1 H FS2 H spread spectrum mode Pout 15W f 1kHz RL 8Q Pout 10W f 1kHz RL 160 Efficiency Regulator Output DIGITAL INPUTS SHDN FS_ G_ Input Thresholds Input Leakage Current Note 1 All devices are 100 production tested at 25 C All temperature limits are guaranteed by design Note 2 Testing performed with a resistive load in series with an inductor to simulate an actual speaker load For RL 80 L 68uH For RL 4Q L 33UH Note 3 PSRR is specified with the amplifier inputs connected to AGND throug
5. 10 2160 10 5 5 n E 8 8 6 2 6 THD N 1 4 4 Ay 1648 2 THD N 10 2 0 2 4 6 8 10 12 14 16 18 20 40 13 1 19 22 25 10 00 OUTPUT POWER W SUPPLY VOLTAGE V LOAD RESISTANCE OUTPUT POWER COMMON MODE REJECTION RATIO POWER SUPPLY REJECTION RATIO vs LOAD RESISTANCE vs FREQUENCY vs FREQUENCY Av 16d8B e 8 8 RL 8Q 3 200mVp p 8 Vpp 15V 5 B 5 5 53 1 10 100 10 100 10k 100k 10 00 1k 10k 100k LOAD RESISTANCE FREQUENCY Hz FREQUENCY Hz CROSSTALK vs FREQUENCY OUTPUT FREQUENCY SPECTRUM OUTPUT FREQUENCY SPECTRUM 0 20 2 FFM MODE SSM MODE 8 8 Ay 16dB 0 Ay 1608 gt 3 NWEIGHTED E UNWEIGHTED 18 2 1kHz 6 20 fin 1kHz o amp 4 m Pout 5W Pout 5W S c a S 40 RL 8Q x E z 8 60 5 6 2 3 3 55 80 80 em 5 100 m 120 120 140 0 00k 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 10 12 14 16 18 20 FREQUENCY Hz FREQUENCY kHz FREQUENCY kHz MAXIM 5 P0Z6XVW E0OZ6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Typical Operating Characteristics continued with 40 68uH with 8Q part in SSM mode 136uH with 160 measurement BW 22Hz to 22kHz unless otherwise noted WIDEBAND OUTPUT SPECTRUM WIDEBAND OUTPUT SPECTRUM OUTPUT FREQUENCY SPECTRUM FFM MODE SSM MODE 20 2 0 2 a SSMMODE 3 3 3 Ay 16dB RB
6. E SIDE RESPECTIVELY DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS DRAWING CONFORMS TO JEDEC MO220 EXCEPT THE EXPOSED PAD DIMENSIONS OF BDALLAS 14877 1 3 4 5 6 amp 15677 1 non AVIALAL VI WARPAGE SHALL NOT EXCEED 0 10 mm A MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY me PACKAGE OUTLINE 12 NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY 32 44 48 56L THIN QFN 7x7x0 8mm DRAWING NOT TO SCALE MAKIM DOCUMENT Ra 2 19 26 0 6 MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers The package drawin Package Information continued 9 5 in this data sheet may not reflect the most current specifications For the latest package outline information go to www maxim ic com packages SEATING DRAWING NOT TO SCALE COMMON DIMENSIONS 16L 5x5 20L 5 5 5 zer sso s os oe aaa 2 elos 01 0 20 025 0 30 ou or 0 20 REF 0 20 0 25 0 30 0 15 0 20 0 25 IT BSC 5 10 4 90 5 00 Ed 4 90 5 00 510 500 510 90 500 4 500 540 050 BSC 0 50 BSC os 10 25 E faao oe jose oaslass ses os ss 28 0 40 BSC 025 10231 ss a aaa asa oan ano NOTES 1 DIMENSIONING amp TOLERANCING CONFORM TO ASME Y14 5M 19
7. drain of 8uW Due to the high efficiency of the Class D amplifier this represents an additional quiescent current draw of 8uW Vpp 100 x n which is in the order of a few microamps Input Amplifier Differential Input The MAX9703 MAX9704 feature a differential input struc ture making them compatible with many CODECs and offering improved noise immunity over a single ended input amplifier In devices such as PCs noisy digital sig nals can be picked up by the amplifier s input traces The signals appear at the amplifiers inputs as common mode noise A differential input amplifier amplifies the difference of the two inputs any signal common to both inputs is canceled Single Ended Input The MAX9703 MAX9704 can be configured as single ended input amplifiers by capacitively coupling either input to AGND and driving the other input Figure 4 Component Selection Input Filter An input capacitor CIN in conjunction with the input impedance of the MAX9703 MAX9704 forms a high pass filter that removes the DC bias from an incoming signal The AC coupling capacitor allows the amplifier to bias the signal to an optimum DC level Assuming 0 47 UF SINGLE ENDED AUDIO INPUT bul MAXI MAX9703 IN MAX9704 Figure 4 Single Ended Input zero source impedance the 3dB point of the highpass filter is given by 1 f o SdB 2nRiNCIN Choose CIN so is well below the lowest frequency of int
8. muted the outputs stop switching muting the speaker Mute only affects the output stage and does not shut down the device To mute the MAX9703 MAX9704 drive SS to PGND by using a MOSFET pulldown Figure 3 Driving SS to PGND during the power up down or shutdown turn on cycle optimizes click and pop suppression 10 SS MAXIM MAX9703 MAX9704 GPIO MUTE SIGNAL Figure 3 MAX9703 MAX9704 Mute Circuit Applications Information Filterless Operation Traditional class D amplifiers require an output filter to recover the audio signal from the amplifier s PWM out put The filters add cost increase the solution size of the amplifier and can decrease efficiency The tradi tional PWM scheme uses large differential output swings 2 x Vpp peak to peak and causes large ripple currents Any parasitic resistance in the filter compo nents results in a loss of power lowering the efficiency The MAX9703 MAX9704 do not require an output filter The devices rely on the inherent inductance of the speaker coil and the natural filtering of both the speak er and the human ear to recover the audio component of the square wave output Eliminating the output filter results in a smaller less costly more efficient solution Because the frequency of the MAX9703 MAX9704 out put is well beyond the bandwidth of most speakers voice coil movement due to the square wave frequency is very small Although this movement is small a speak er not des
9. 0 5 RL 4Q Z E 4 0 1 30 FFM 335 2 2 Vpp 12V 1 Ay 1608 1kHz 0 01 0 0 2 4 6 8 10 12 14 16 18 20 0123456 78 9 10111213141516171819 20 012 3 4 5 6 7 8 9 10 OUTPUT POWER W OUTPUT POWER W OUTPUT POWER W 4 MAKLM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Typical Operating Characteristics continued 33uH with 40 68uH with 80 part in SSM mode 136uH with 160 measurement BW 22Hz to 22kHz unless otherwise noted OUTPUT POWER OUTPUT POWER EFFICIENCY vs OUTPUT POWER vs SUPPLY VOLTAGE vs LOAD RESISTANCE 20 20 2 E E Vpp 15V 3 18 Ar 1608 THD N 10 8 3 16 2 16 3 AE 14 8Q 14 12 12 e z 5
10. 00 600 FREQUENCY MHz Figure 1 MAX9704 EMI Spectrum 9in PC Board trace 3in Twisted Pair Speaker Cable MAXIM 9 P0Z6XVW E0Z6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers EFFICIENCY vs OUTPUT POWER gt ce i L 6 8 10 1 OUTPUT POWE 4 16 18 20 Figure 2 MAX9704 Efficiency vs Class AB Efficiency Shutdown The MAX9703 MAX9704 have a shutdown mode that reduces power consumption and extends battery life Driving SHDN low places the device in low power 0 20A shutdown mode Connect SHDN to a logic high for normal operation Click and Pop Suppression The MAX9703 MAX9704 feature comprehensive click and pop suppression that eliminates audible transients on startup and shutdown While in shutdown the H bridge is pulled to PGND through 330kQ During start up power up the input amplifiers are muted and internal loop sets the modulator bias voltages to the cor rect levels preventing clicks and pops when the H bridge is subsequently enabled Following startup a soft start function gradually unmutes the input amplifiers The value of the soft start capacitor has an impact on the click pop levels For optimum performance Css should be at least 0 18uF with a voltage rating of at least 7V Mute Function The MAX9703 MA9704 features a clickless popless mute mode When the device is
11. 19 3160 Rev 7 3 06 MAKINI 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers General Description The MAX9703 MAX9704 mono stereo Class D audio power amplifiers provide Class AB amplifier performance with Class D efficiency conserving board space and eliminating the need for a bulky heatsink Using a Class D architecture these devices deliver up to 15W while offering up to 78 efficiency Proprietary and protected modulation and switching schemes render the traditional Class D output filter unnecessary The MAX9703 MAX9704 offer two modulation schemes a fixed frequency mode FFM and a spread spectrum mode SSM that reduces EMl radiated emissions due to the modulation frequency The device utilizes a fully differential architecture a full bridged output and com prehensive click and pop suppression The MAX9703 MAX9704 feature high 80dB PSRR low 0 07 THD N and SNR in excess of 95dB Short cir cuit and thermal overload protection prevent the devices from being damaged during a fault condition The MAX9703 is available in a 32 pin TQFN 5mm 5mm x 0 8mm package The MAX9704 is available in a 32 pin TQFN 7mm x 7mm x 0 8mm package Both devices are specified over the extended 40 C to 85 C temperature range Applications LCD TVs Hands Free Car LCD Monitors Phone Adaptors Automotive Desktop PCs LCD Projectors Features 9 Filterless Class D Amplifier Unique Spread Spectrum Mode Offe
12. 55 6 315 325 335 315 3 35 855 7 2 60 2 70 2 80 2 60 2 70 280 eesse _ ais 333 3 5 aes 335 1 315 315 335 T3255 3 3 00 A gt 3 00 am 320 3255 4 3 00 3 00 310 20 4 300 310 E 300 310 320 13255 5 3 10 300 310 320 T3eSSN 1 3 00 340 3 00 310 380 1 340 350 240 aso 260 raoss 2 340 350 260 340 aso 360 Tassu 340 350 250 260 PACKAGE OUTLINE 16 20 28 32 40L THIN QFN 5x5x0 80mm Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product No circuit patent licenses are implied Maxim reserves the right to change the circuitry and specifications without notice at any time 20 2006 Maxim Integrated Products MAXIM Maxim Integrated Products 120 San Gabriel Drive Sunnyvale CA 94086 408 737 7600 is a registered trademark of Maxim Integrated Products Inc
13. 94 2 ALL DIMENSIONS ARE IN MILLIMETERS ANGLES ARE IN DEGREES 3 15 THE TOTAL NUMBER OF TERMINALS THE TERMINAL 1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95 1 012 DETAILS OF TERMINAL 1 IDENTIFIER ARE OPTIONAL BUT MUST BE LOCATED WITHIN THE ZONE INDICATED THE TERMINAL 1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 025 mm AND 0 30 mm FROM TERMINAL TIP ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY 7 DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS 9 DRAWING CONFORMS TO JEDEC M0220 EXCEPT EXPOSED PAD DIMENSION FOR 855 3 T2855 6 T4055 1 AND T4055 2 Ads WARPAGE SHALL NOT EXCEED 040 mm 11 MARKING 1 FOR PACKAGE ORIENTATION REFERENCE ONLY 12 NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION 50605 14 ALL DIMENSIONS APPLY TO BOTH LEADED AND PbFREE PARTS DRAWING NOT TO SCALE A b 4 0 10 3 QFN THIN EPS PIN 1 LD 0 35x45 A R IS OPTIONAL PACKAGE DUTLINE 16 20 28 32 40L THIN QFN 5 5 0 80 MAX 3 20 320 320 320 320 335 T2855 3 315 315 335 En 2 80 um 260 270 20 260 270 280 128
14. V Internal Regulator Output Bypass with a 0 01uF capacitor to AGND Analog Ground Negative Input Positive Input Soft Start Connect a 0 47uF capacitor from SS to PGND to enable soft start feature Active Low Shutdown Connect SHDN to PGND to disable the device Connect to a logic high for normal operation Gain Select Input 1 Gain Select Input 2 Frequency Select Input 1 27 28 Frequency Select Input 2 Negative Audio Output 29 30 Positive Audio Output Left Channel Negative Input 9 10 INL Left Channel Positive Input 15 Right Channel Negative Input 16 Right Channel Positive Input 25 26 Right Channel Negative Audio Output Right Channel Positive Audio Output Left Channel Negative Audio Output MAXIM OUTL EP Left Channel Positive Audio Output Exposed Paddle Connect to GND P0Z6XVW E0OZ6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Detailed Description The MAX9703 MAX9704 filterless Class D audio power amplifiers feature several improvements to switch mode amplifier technology The MAX9703 is a mono amplifier the MAX9704 is a stereo amplifier These devices offer Class AB performance with Class D effi ciency while occupying minimal board space A unique filterless modulation scheme and spread spec trum switching mode create a compact flexible low noise efficient audio power ampl
15. W 10Hz A WEIGHTED 2 20 5 2 00 5 20 fin 1kHz 3 Pour 5W 40 280 OUTPUT MAGNITUDE dB OUTPUT AMPLITUDE dBV OUTPUT AMPLITUDE 420 100 100 140 120 120 0 2 4 6 8 10 12 14 16 18 20 100k 1 10M 00M 100k 1 10M 00M FREQUENCY kHz FREQUENCY Hz FREQUENCY Hz SUPPLY CURRENT SHUTDOWN CURRENT TURN ON TURN OFF RESPONSE vs SUPPLY VOLTAGE vs SUPPLY VOLTAGE MAX9703 04 toc22 mE 35 0 35 Css 180pF u 30 S _ 5 3 SHDN 5V div 5 0 m ce 20 0 20 a z gt 15 0 15 1V dv 8 OUTPUT B 10 040 72 5 0 05 0 0 20ms div 10 13 1 19 22 25 10 12 14 16 18 20 SUPPLY VOLTAGE V SUPPLY VOLTAGE V 6 MAKLM PIN Spread Spectrum Class D Amplifiers MAX9703 MAX9704 10W Stereo 15W Mono Filterless Pin Description FUNCTION 1 2 23 24 3 4 21 22 1 2 23 24 3 4 21 22 Power Ground Power Supply Input Charge Pump Flying Capacitor Negative Terminal 8 17 20 25 26 31 32 Charge Pump Flying Capacitor Positive Terminal Pump Hold Capacitor Connect a 1uF capacitor from CHOLD to Vpp No Connection Not internally connected 9 6
16. ance when driving higher load impedance see the Typical Operating Characteristics If a 120 to 160 load is not available select a lower supply voltage when dri ving 6Q to 100 loads P0Z6XVW E0Z6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Functional Diagrams 10V TO 25V MAXIM MAX9703 CHARGE PUMP LOGIC INPUTS SHOWN FOR Ay 1608 SSM Vin LOGIC HIGH gt 2 5 CHOOSE CAPACITOR VOLTAGE RATING gt Vpp SYSTEM LEVEL REQUIREMENT 14 MAXIM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Functional Diagrams continued 10V TO 25V MAXIM GAIN MAX9704 18 rom CONTROL SHUTDOWN CHARGE PUMP CONTROL LOGIC INPUTS SHOWN FOR Ay 16dB SSM Vin LOGIC HIGH gt 2 5V CHOOSE CAPACITOR VOLTAGE RATING gt Vpp SYSTEM LEVEL REQUIREMENT MAXIM 15 P0Z6XVW E0Z6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers System Diagram SHDN OUTL INL OUTL MAXIM MAX9704 INR OUTR 100 SHDN MAXIM MAX9722B OU TL L LOGIC INPUTS SHOWN FOR 1608 SSM BULK CAPACITANCE IF NEEDED MAXIM TOP VIEW MAKIN 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Pin Configurations
17. erest Setting f 3dB too high affects the low fre quency response of the amplifier Use capacitors with dielectrics that have low voltage coefficients such as tantalum or aluminum electrolytic Capacitors with high voltage coefficients such as ceramics may result in increased distortion at low frequencies Charge Pump Capacitor Selection Use capacitors with an ESR less than 100mQ for opti mum performance Low ESR ceramic capacitors mini mize the output resistance of the charge pump For best performance over the extended temperature range select capacitors with an X7R dielectric Flying Capacitor C1 The value of the flying capacitor C1 affects the load regulation and output resistance of the charge pump A C1 value that is too small degrades the device s ability to provide sufficient current drive Increasing the value of C1 improves load regulation and reduces the charge pump output resistance to an extent Above 1uF the on resistance of the switches and the ESR of C1 and C2 dominate Hold Capacitor C2 The output capacitor value and ESR directly affect the rip ple at CHOLD Increasing C2 reduces output ripple Likewise decreasing the ESR of C2 reduces both ripple and output resistance Lower capacitance values can be used in systems with low maximum output power levels Output Filter The MAX9703 MAX9704 do not require an output filter and can pass FCC emissions standards with unshield ed speaker cables However outpu
18. f the specifications is not implied Exposure to absolute maximum rating conditions for extended periods may affect device reliability ELECTRICAL CHARACTERISTICS Vpp 15V AGND PGND OV SHDN gt Av 16dB Css Cin 0 47uF CREG 0 01uF C1 100nF C2 1uF FS1 FS2 PGND fs 660 2 RL connected between OUTL and OUTL and OUTR and OUTR TA TMIN to Tmax unless otherwise noted Typical values are at Ta 25 C Notes 1 2 PARAMETER GENERAL SYMBOL CONDITIONS Supply Voltage Range Inferred from PSRR test Quiescent Current Shutdown Current IDD ISHDN MAX9703 MAX9704 RL OPEN Turn On Time Amplifier Output Resistance in Shutdown Css 470nF Css 180nF SHDN PGND Input Impedance Av 13dB Av 16dB Av 19 1dB Av 29 6dB 10 15 Voltage Gain 01 1 02 1 01 02 1 29 4 18 9 29 6 19 1 G1 H G2 H Gain Matching Output Offset Voltage Between channels MAX9704 Common Mode Rejection Ratio fin 1kHz input referred Power Supply Rejection Ratio Note 3 Vpp 10V to 25V fRIPPLE 1 2 200mvVP p ripple ils fRIPPLE 20kHz MAXI 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers ELECTRICAL CHARACTERISTICS continued Vpp 15V AGND PGND OV SHDN gt Av 16dB Css CiN 0 47uF CREG 0 01uF C1 100nF C2 1pF FS1
19. fiers ABSOLUTE MAXIMUM RATINGS All voltages referenced to PGND Continuous Power Dissipation TA 70 C VDD to PGND AGND l terit tenet 30V Single Layer Board OUTR_ OUTL_ C1N 0 3V to Vpp 0 3V MAX9703 32 Pin TQFN derate 21 3mW C Vpp 0 3V to CHOLD 0 3V above ul e alis 1702 1mW E Vpp 0 3V to 40V MAX9704 32 Pin TQFN derate 27mW C All Other Pins to PGND aa 0 3V to 12V ADOVE u task ans ele 2162 2mW Duration of OUTR_ OUTL_ Multilayer Board Short Circuit to PGND MAX9703 32 Pin TQFN derate 34 5mW C Continuous Input Current Vpp PGND E above x 0 lusto sh s Mas huku 2758 6mW Continuous Input MAX9704 32 Pin TQFN derate 37mW C Continuous Input Current all other pins 21616 1 2 2400 E 2963 0mW Junction Temperature a a a 150 C Operating Temperature Range Storage Temperature Range Lead Temperature soldering 10s Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections o
20. h Cin Note 4 The MAX9704 continuous 8Q and 16Q power measurements account for thermal limitations of the 32 pin TQFN EP package Continuous 4Q power measurements account for short circuit protection of the MAX9703 MAX9704 devices MAXIM 3 26 0 6 MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Typical Operating Characteristics with 4Q 68uH with 8Q part in SSM mode 136uH with 160 measurement BW 22Hz to 22kHz unless otherwise noted
21. ifier The differential input architecture reduces common mode noise pick up and can be used without input coupling capacitors The devices can also be configured as a single ended input amplifier Comparators monitor the device inputs and compare the complementary input voltages to the triangle wave form The comparators trip when the input magnitude of the triangle exceeds their corresponding input voltage Operating Modes Fixed Frequency Modulation FFM Mode The MAX9703 MAX9704 feature three FFM modes with different switching frequencies Table 1 In FFM mode the frequency spectrum of the Class D output consists of the fundamental switching frequency and its associated harmonics see the Wideband Output Spectrum FFM Mode graph in the Typical Operating Characteristics The MAX9703 MAX9704 allow the switching frequency to be changed by 35 should the frequency of one or more of the harmonics fall in a sensitive band This can be done at any time and does not affect audio reproduction Spread Spectrum Modulation SSM Mode The MAX9703 MAX9704 feature a unique spread spec trum mode that flattens the wideband spectral compo nents improving EMI emissions that may be radiated Table 1 Operating Modes SWITCHING MODE kHz L 670 L 940 H L H L 470 by the speaker and cables This mode is enabled by setting FS1 FS2 H In SSM mode the switching fre quency varies randomly by 7 around the center fre quenc
22. igned to handle the additional power can be damaged For optimum results use a speaker with a series inductance gt Typical 8Q speakers exhibit series inductances in the range of 30uH to 100UH Optimum efficiency is achieved with speaker induc tances gt Internal Regulator Output VREG The MAX9703 MAX9704 feature an internal 6V regula tor output VREG The MAX9703 MAX9704 REG output pin simplifies system design and reduces system cost by providing a logic voltage high for the MAX9703 MAX9704 logic pins G_ FS VREG is not available as a logic voltage high in shutdown mode Do not apply VREG as a 6V potential to surrounding system components Bypass REG with a 6 3V 0 01uF capacitor to AGND MAXIM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Gain Selection The MAX9703 MAX9704 feature an internally set logic selectable gain The G1 and G2 logic inputs set the gain of the MAX9703 MAX9704 speaker amplifier Table 2 Table 2 Gain Selection GAIN dB Output Offset Unlike a Class AB amplifier the output offset voltage of Class D amplifiers does not noticeably increase quies cent current draw when a load is applied This is due to the power conversion of the Class D amplifier For example an 8mV DC offset across an 8Q load results in 1mA extra current consumption in a class AB device In the Class D case an 8mV offset into 8Q equates to an additional power
23. nnected to the exposed paddle of the MAX9704 TQFN package Additionally can be reduced by attaching a heatsink adding a fan or mount ing a vertical PC board Load Impedance The on resistance of the MOSFET output stage in Class D amplifiers affects both the efficiency and the peak cur rent capability Reducing the peak current into the load reduces the I2R losses in the MOSFETs thereby increas ing efficiency To keep the peak currents lower choose the highest impedance speaker which can still deliver the desired output power within the voltage swing limits of the Class D amplifier and its supply voltage Although most loudspeakers are either 4Q or 8Q there are other impedances available which can provide a more thermally efficient solution Another consideration is the load impedance across the audio frequency band A loudspeaker is a complex electromechanical system with a variety of resonances In other words an 8Q speaker is usually only 8Q imped ance within a very narrow range and often extends well below 8O reducing the thermal efficiency below what is expected This lower than expected impedance can be further reduced when a crossover network is used in a multi driver audio system Optimize MAX9703 MAX9704 Efficiency with Load Impedance and Supply Voltage To optimize the efficiency of the MAX9703 MAX9704 load the output stage with 120 to 160 speakers The MAX9703 MAX9704 exhibits highest efficiency perfor m
24. nuous sine wave the actual thermal impact on the Class D amplifier is highly reduced If the thermal performance of a system is being evaluated it is important to use actual audio sig nals instead of sine waves for testing If sine waves must be used the thermal performance will be less than the System s actual capability PC Board Thermal Considerations The exposed pad is the primary route of keeping heat away from the IC With a bottom side exposed pad the PC board and its copper becomes the primary heatsink for the Class D amplifier Solder the exposed pad to a large copper polygon Add as much copper as possible from this polygon to any adjacent pin on the Class D amplifier as well as to any adjacent components provid ed these connections are at the same potential These copper paths must be as wide as possible Each of these paths contributes to the overall thermal capabilities of the system The copper polygon to which the exposed pad is attached should have multiple vias to the opposite side of the PC board where they connect to another copper polygon Make this polygon as large as possible within the system s constraints for signal routing 20ms div Figure 5 RMS Comparison of Sine Wave vs Audio Signal MAXIM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers Additional improvements are possible if all the traces from the device are made as wide as possible Although the IC pins are not the p
25. rimary thermal path of the pack age they do provide a small amount The total improve ment would not exceed about 10 but it could make the difference between acceptable performance and ther mal problems Auxiliary Heatsinking If operating in higher ambient temperatures it is possible to improve the thermal performance of a PC board with the addition of an external heatsink The thermal resis tance to this heatsink must be kept as low as possible to maximize its performance With a bottom side exposed pad the lowest resistance thermal path is on the bottom of the PC board The topside of the IC is not a significant thermal path for the device and therefore is not a cost effective location for a heatsink Thermal Calculations The die temperature of a Class D amplifier can be esti mated with some basic calculations For example the die temperature is calculated for the below conditions e TA 40 C e POUT 2x8W 16W e RL 160 e Efficiency n 87 e 0JA 27 C W First the Class D amplifiers power dissipation must be calculated 16W Ppiss Pout gg 16W 24W Then the power dissipation is used to calculate the die temperature Tc as follows Tc TA PDISS 40 C 2 4W x 27 C W 104 8 C Decreasing the ambient temperature or reducing 0JA will improve the die temperature of the MAX9704 0JA can be reduced by increasing the copper size weight of the ground plane co
26. rs 5dB Emissions Improvement Over Conventional Methods Up to 78 Efficient RL 80 Up to 88 Efficient RL 160 15W Continuous Output Power into 80 MAX9703 2x10W Continuous Output Power into 80 MAX9704 Low 0 07 THD N High PSRR 804 at 1 2 10V to 25V Single Supply Operation Differential Inputs Minimize Common Mode Noise Pin Selectable Gain Reduces Component Count Industry Leading Click and Pop Suppression Low Quiescent Current 24mA Low Power Shutdown Mode 0 2uA Short Circuit and Thermal Overload Protection oof 9 99 9 9 Available in Thermally Efficient Space Saving Packages 32 Pin TQFN 5mm x 5mm x 0 8mm MAX9703 32 Pin TQFN 7mm x 7mm x 0 8mm MAX9704 Ordering Information PIN PACKAGE 32 TQFN EP 32 TQFN EP AMP Mono Stereo PART PKG CODE MAX9703ETJ T3255 3 MAX9704ETJ T3277 2 Note All devices specified for over 40 C to 85 C operating temperature range EP Exposed paddle Denotes lead free package Block Diagrams MAXIM MAX9703 Pin Configurations appear at end of data sheet MAXIM MAXIM MAX9704 H BRIDGE Maxim Integrated Products 1 For pricing delivery and ordering information please contact Maxim Dallas Direct at 1 888 629 4642 or visit Maxim s website at www maxim ic com P0Z6XVW E0OZ6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Ampli
27. t filtering can be 11 P0Z6XVW E0OZ6XVIMW MAX9703 MAX9704 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers used if a design is failing radiated emissions due to board layout or cable length or the circuit is near EMI sensitive devices Use a ferrite bead filter when radiat ed frequencies above 10MHz are of concern Use an LC filter when radiated frequencies below 10MHz are of concern or when long leads connect the amplifier to the speaker Refer to the MAX9704 Evaluation Kit schematic for details of this filter Sharing Input Sources In certain systems a single audio source can be shared by multiple devices speaker and headphone ampli fiers When sharing inputs it is common to mute the unused device rather than completely shutting it down preventing the unused device inputs from distorting the input signal Mute the MAX9703 MAX9704 by driving SS low through an open drain output or MOSFET see the System Diagram Driving SS low turns off the Class D output stage but does not affect the input bias levels of the MAX9703 MAX9704 Be aware that during normal operation the voltage at SS can be up to 7V depending on the MAX9703 MAX9704 supply Supply Bypassing Layout Proper power supply bypassing ensures low distortion operation For optimum performance bypass Vpp to PGND with a 0 1uF capacitor as close to each Vpp pin as possible A low impedance high current power sup ply connection to Vpp is ass
28. umed Additional bulk capacitance should be added as required depending on the application and power supply characteristics AGND and PGND should be star connected to system ground Refer to the MAX9704 Evaluation Kit for layout guidance Class D Amplifier Thermal Considerations Class D amplifiers provide much better efficiency and thermal performance than a comparable Class AB ampli fier However the system s thermal performance must be considered with realistic expectations and include con sideration of many parameters This section examines Class D amplifiers using general examples to illustrate good design practices Continuous Sine Wave vs Music When a Class D amplifier is evaluated in the lab often a continuous sine wave is used as the signal source While this is convenient for measurement purposes it repre sents a worst case scenario for thermal loading on the amplifier It is not uncommon for a Class D amplifier to enter thermal shutdown if driven near maximum output power with a continuous sine wave 12 Audio content both music and voice has a much lower RMS value relative to its peak output power Figure 5 shows a sine wave and an audio signal in the time domain Both are measured for RMS value by the oscillo scope Although the audio signal has a slightly higher peak value than the sine wave its RMS value is almost half that of the sine wave Therefore while an audio sig nal may reach similar peaks as a conti
29. y 670kHz The modulation scheme remains the same but the period of the triangle waveform changes from cycle to cycle Instead of a large amount of spec tral energy present at multiples of the switching fre quency the energy is now spread over a bandwidth that increases with frequency Above a few megahertz the wideband spectrum looks like white noise for EMI purposes see Figure 1 Efficiency Efficiency of a Class D amplifier is attributed to the region of operation of the output stage transistors In a Class D amplifier the output transistors act as current steering switches and consume negligible additional power Any power loss associated with the Class D out put stage is mostly due to the I2R loss of the MOSFET on resistance and quiescent current overhead The theoretical best efficiency of a linear amplifier is 78 however that efficiency is only exhibited at peak output powers Under normal operating levels typical music reproduction levels efficiency falls below 30 whereas the MAX9704 still exhibits gt 78 efficiency under the same conditions Figure 2 MAXIM 10W Stereo 15W Mono Filterless Spread Spectrum Class D Amplifiers MAXIM MAX9704 L1 L4 0 050 DCR 70Q AT 100MHz FAIR RITE FERRITE BEAD 2512067007Y3 A7 CE LIMIT AMPLITUDE dBuV m MAX9704 OUTPUT SPECTRU 400 5
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MAXIM MAX9703/MAX9704 handbook