PAM8406 Alternative 5W Stereo Audio Amplifier Key Features General Description Alternative Output: Class-D or Class-AB 5W Output at 10% THD with a 2 Load and 5V Power Supply at Class D mode 3W Output at 10% THD with a 4 Load and 5V Power Supply Filterless, Low Quiescent Current and No EMI Low THD+N at Fully Output Range Superior Low Noise Efficiency up to 90% with Class D Mode No Pop At Turn-on/off Fully Short Circuit Protection With Auto Recovery Thermal Shutdown Few External Components to Save the Space and Cost SOP-16L/SOP-16(EP) Package The PAM8406 is a 5W audio amplifier with an alternative option between Class-D and Class-AB output which makes PAM8406 very ideally for the applications efficiency-EMI compatible. PAM8406 offers low THD+N, high SNR allowing it to achieve high-quality sound reproduction. The f u ll y d i ff e r e n ti a l o u t p u t w it h n e w f i lt e r le s s architecture(Class D mode) allows the device to drive the speaker directly , requiring no low-pass output filters and DC blocking capacitors, thus to save the system cost and PCB area. The efficiency of the PAM8406 is up to 90%. It can e xte nd th e ba tter y life , id ea lly for p or table applications. The PAM8406 is fully protected against faults with short circuit protection and thermal protection. Applications The PAM8406 is available in SOP-16L/ SOP16(EP) package. LCD TVs Mutimedia Speakers AM/FM System DABs Typical Application VCC 1 uF VDD Cin Rin INL INL INR INR 1uF PVDDL 1uF PVDDR +OUT_L PGNDL Cin Rin MO DE H: Class D(default) L: Class AB -OUT_L SHDN -OUT_R MUTE PGNDR MODE VREF GND +OUT_R 1uF 11/2011 Rev1.0 1 PAM8406 Alternative 5W Stereo Audio Amplifier Block Diagram + + - - CURRENT PROTECTION - - + + PV DD L Pin Configuration & Marking Information Top View SOP-16/SOP-16(EP) 1 16 2 15 3 14 4 13 5 12 6 11 7 10 8 9 X: Internal Code A: Assembly Code T: Testing Code Y: Year WW: Week LL: Internal Code 11/2011 Rev1.0 2 PAM8406 Alternative 5W Stereo Audio Amplifier Pin Descriptions Pin Number Pin Name Description 1 +OUT_L Left Channel Positive Output 2 PGNDL Power GND 3 -OUT_L Left Channel N egative Output 4 PVDDL Power VDD 5 MUTE Mute Control Input 6 VDD Analog VDD 7 INL Left Channel Input 8 VREF Internal analog reference, connect a bypass capacitor from VREF to GND 9 MODE High: Class-D ; Low: Class-AB 10 INR Right Channel Input 11 GND Analog GND 12 SH DN Shutdown Control Input (active low) 13 PVDDR Power VDD 14 -OUT_R Right Channel Negative Output 15 PGNDR Power GND 16 +OUT_R Right Channel Positive Output active low Absolute Maximum Ratings These are stress ratings only and functional operation is not implied Exposure to absolute maximum ratings for prolonged time periods may affect device reliability All voltages are with respect to ground Supply Voltage ...........................................6.0V Input Voltage.............................-0.3V to V D D+0.3V Operation Temperature Range.........-40¡C to 85 ¡C Maximum Junction Temperature..................150¡C Operation Junction Temperature.....-40 ¡C to 125¡C Storage Temperature.....................-65 ¡C to 150¡C Soldering Temperature....................... 300¡C, 5sec Recommended Operating Conditions Supply voltage Range........................ 2.5V to 5.5V Operation Temperature Range.........-40 ¡C to 85 ¡C Junction Temperature Range.........-40 ¡C to 125¡C Thermal Information Par ameter Sym bol Package Maximum Unit Thermal Resistance (Junction to Ambient) JA SOP-16 110 ¡ C/W Thermal Resis tance (Junction to Case) JC SOP-16 23 ¡ C/W 11/2011 Rev1.0 3 PAM8406 Alternative 5W Stereo Audio Amplifier Electrical Characteristic V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted. Symbol Parameter VIN Supply Po wer Te st Condit ions (Class D) THD+N=1 %,f=1kHz, RL =2 (Class D) THD+N=10%,f=1kHz, R L=4 Output Power THD+N=1 %,f=1kHz, RL =4 THD+N=10%,f=1kHz, R L=8 THD+N=1 %,f=1kHz, RL =8 VDD=5.0V,Po=0.1W ~1 W,R L=8 5 .0 VDD=3.6V 2 .6 VDD=2.5V 1 .3 VDD=5.0V 4 .0 VDD=3.6V 2 .0 VDD=2.5V 1 .0 VDD=5.0V 3.14 VDD=3.6V 1 .5 VDD=2.5V 0.76 VDD=5.0V 2.55 VDD=3.6V 1.45 VDD=2.5V 0.63 VDD=5.0V 1 .8 VDD=3.6V 0.92 VDD=2.5V 0.44 VDD=5.0V 1 .6 VDD=3.6V 0.76 VDD=2.5V 0.36 f=1kHz VDD=5.0V,Po=0.1W ~2 W,R L=4 Total Harmonic Distortion Plus V DD=3.6V,Po=0.05W~1W,RL =4 No ise VDD=5.0V,Po=0.1W ~2 W,R L=2 (Class D) PSRR Power Sup ply R ip ple Rejection 0.11 W W W W W % % 0.15 f=1kHz % 0.11 24 V DD=5 .0V, Inpu ts ac- grounded with W 0.15 f=1kHz (Class D) Gain 0.15 V 0.11 V DD=3.6V,Po=0.05W~1W,RL =2 Gv MAX UNIT 5.5 VDD=5.0V VDD=3.6 V,Po=0.05W~0.5W ,RL=8 THD+N TYP 2.5 THD+N=10%,f=1kHz, R L=2 Po MIN f=10 0Hz -7 0 f=1kHz -6 5 dB dB Cs Crosstalk VDD=5V,Po=0.5W,R L=8 ,Gv=24d B f=1kHz -9 5 dB SNR Sig nal- to-noise ratio VD D =5V, THD=1%,Gv=24dB f=1kHz 90 dB 11/2011 Rev1.0 4 PAM8406 Alternative 5W Stereo Audio Amplifier Electrical Characteristic V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted. Symbol Para meter Vn Outpu t Noise Test Conditions VDD=5V, Inputs ac-g rounded RL =8 , THD=1 0% Efficiency RL =4 , THD=1 0% RL =2 , THD=1 0% Quiescent Cu rrent ( Cla ss D) IQ Quiescent Cu rrent (Class AB) MIN A-weig hting 100 No A-we ighting 150 UNIT uV 85 F=1kHz % 80 10 No L oad 8 VD D=2.5V 6 VD D=5.0V 25 VD D=3.6V MAX 90 Class D Mode VD D=5.0V VD D=3.6V TYP No L oad mA 15 VD D=2.5V mA 10 IMUTE Muting Current VD D=5.0V VMUT E=0.3V 2.4 mA ISD Shu tdown Curr ent VDD=2.5V to 5.5V Vsd=0.3V <1 µA PMOS 180 NMOS 140 Class D 250 kHz 10 mV Rdson Static Drain-to-source On-state Resistor I DS=500mA,Vgs=5V fsw Switching Frequency VDD=2.5V to 5.5V Vos Output Offset Volta ge Inp ut AC-GND, V DD=5 V VI H En abl e Input High Voltage VD D=5.0V VIL Enable VD D=5.0V Input Low Vol tage VI H MUTE Inpu t High Voltage VD D=5.0V VIL MUTE Input Low Voltage VD D=5.0V VI H MODE Input High Voltage VD D=5.0V VIL MODE Input Lo w Voltage VD D=5.0V OTP Ove rTemp eratu re Protection OTH Over Temp erature Hysterisis m 1.4 0.4 1.4 0.4 V V 1.4 0.4 V 150 No Load, Jun ction Temperature VD D=5V 30 ¡C 11/2011 Rev1.0 5 PAM8406 Alternative 5W Stereo Audio Amplifier Typical Operating Characteristics (TA =25¡C) V D D =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted. 1. THD+N vs Output Power 2. THD+N vs Output Power 60 60 20 20 V DD=3.6V % V DD=3.6V 10 10 5 5 2 % V DD=2.5V 1 2 V DD=2.5V 1 V DD=5V 0.5 VDD =5V 0.5 0.2 0.2 0.1 0.06 1m 2m 5m 10m 20m 50m 100m 200m 500m 1 0.08 1m 2 2m 5m 10m 20m 50m W 100m 200m Class D, R L=8 , f=1kHz 1 2 5 Class D, R L =4 , f=1kHz 3. THD+N vs Output Power 4. THD+N vs Output Power 60 60 20 V DD=3.6V 20 % 500m W VDD =5V 10 10 5 5 2 % 2 1 VDD =2.5V 0.5 VDD =2.5V 1 V DD=3.6V 0.2 0.5 VDD =5V 0.1 0.05 0.2 0.02 0.08 1m 2m 5m 10m 20m 50m 100m 200m 500m 1 2 0.01 1m 56 2m 5m 10m 20m 50m Class D, R L=2 , f=1kHz 5. THD+N vs Output Power 2 10k 20k +22. 5 +20 d B g 2 V DD=2.5V +17. 5 C IN =0.47uF +15 +12. 5 VDD =3.6V 0.5 A 0.2 +10 C IN =0.1uF +7. 5 0.1 +5 0.05 0.02 1m 1 C IN =1uF +25 V DD=5V 5 1 500m 6. Frequency Response +27. 5 10 % 200m Class AB, RL =8 , f=1kHz 60 20 100m W W +2. 5 2m 5m 10m 20m 50m 100m 200m 500m 1 2 +0 20 5 W 50 100 200 500 1k 2k 5k Hz Class AB, R L=4 , f=1kHz 11/2011 Rev1.0 6 PAM8406 Alternative 5W Stereo Audio Amplifier Typical Operating Characteristics (continued) V DD =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted. 8. THD+N vs Output Power (Class AB) 7. THD+N vs Frequency (Class D) 10 10 5 5 2 2 1 0.5 1 Po=0.5W 0.5 % 0.2 Po=0.3W 0.2 Po=0.5W 0.1 % Po=0.3W 0.05 0.1 0.02 Po=1W 0.05 0.01 Po=1W 0. 005 0.02 0. 002 0.01 20 50 100 200 500 1k 2k 5k 10k 0. 001 20 20k 50 100 200 Hz 1k 2k 5k 10k 20k 2k 5k 10k 20k Hz 9.Noise Floor (Class D) 10. Noise Floor (Class AB) -50 -50 -60 -60 -70 d B r 500 -70 d B r -80 -80 -90 -90 A A -100 -100 -110 -110 -120 20 50 100 200 500 1k 2k 5k 10k -120 20 20k 50 100 200 500 1k H R L=4 ,Vin=2.5V/3.3V/3.6V/4.2/5V/5.5V R L=4 ,Vin=2.5V/3.3V/3.6V/4.2/5V/5.5V 11. PSRR (Class D) +0 T 12. PSRR (Class AB) +0 TT TT TTT T -10 -10 -20 -20 -30 -30 -40 d B T -40 d B -50 -50 -60 -60 -70 -70 -80 -80 -90 -90 -100 20 TT 50 100 200 500 1k 2k 5k 10k -100 20 20k Hz 50 100 200 500 1k 2k 5k 10k 20k Hz 11/2011 Rev1.0 7 PAM8406 Alternative 5W Stereo Audio Amplifier Typical Operating Characteristics (continued) V DD =5V, Gain=24dB, R L =8 , both Class D and Class AB mode,T A =25 ¡C , unless otherwise noted. 14. Frequency vs Supply Voltage 13. Quiescent Current vs Supply Voltage 29. 0 270. 0 Clas s D Clas s A B 265. 0 24. 0 260. 0 19. 0 255. 0 14. 0 250. 0 9. 0 245. 0 240. 0 4. 0 2.0 3.0 4 .0 5.0 2. 0 6.0 3.0 Sup ply Volt age(V ) 15.Rds(on) vs Iload 4.0 Supply Volt age(V) 5.0 6. 0 16. Efficiency vs Output Power(Class D) 100 2 70 .0 2 50 .0 P MOS 90 NMOS 80 70 2 30 .0 60 50 2 10 .0 40 1 90 .0 30 20 1 70 .0 2ohm 4ohm 8ohm 10 1 50 .0 0 0 500 1000 1 50 0 2000 0 1000 200 0 3 000 4000 5 000 Ila od(mA ) Po(mW ) 17. Output Power vs Power Supply 7000 8ohm 4ohm 2ohm 6000 5000 4000 3000 2000 1000 0 2 3 4 Supply Voltage(V) 5 6 11/2011 Rev1.0 8 PAM8406 Alternative 5W Stereo Audio Amplifier Application Notes higher than its operation voltage, which will probably damage the device. Therefore, it's recommended to use either 4 Ni-MH (Nickel Metal Hydride) rechargeable batteries or 3 dry or alkaline batteries. 1. When the PAM8406 works in class D mode with LC filters, it should be connected with the speaker before it's powered on, otherwise it will be damaged easily. 4. One should not make the input signal too large. Large signal can cause the clipping of output signal when increasing the volume. This will damage the device b ecause of big gain of the PAM8406 . 2. When the PAM8406 works without LC filters, it's better to add a ferrite chip bead at the outgoing line of speaker for suppressing the possible electromagnetic interference. 3. The re co mmend ed o pera tin g voltage is 5.5V. When the PAM8406 is powered with 4 battery cells, it should be noted that the voltage of 4 new dry or alkaline batteries is over 6.0V, Test Setup for Performance Testing Notes 1. The AP AUX-0025 low pass filter is necessary for class-D amplifier measurement with AP analyzer . 2. Two 22µH inductors are used in series with load resistor to emulate the small speaker for effic iency measurement. 11/2011 Rev1.0 9 PAM8406 Alternative 5W Stereo Audio Amplifier Application Information Maximum Gain capacitors of different types targeting to different types of noise on the power supply leads. For higher frequency transients, spikes, or digital hash on the line, a good low equivalent-seriesresistance (ESR) ceramic capacitor, typically 1.0µF, works best, placing it as close as possible to the device VD D terminal. For filtering lowerfrequency noise signa ls, a large capacitor of 20µF (ceramic) or greater is recommended, placing it near the audio power amplifier. As sh own in b lock dia gram (pag e 2), the PAM8406 has two internal amplifier stages. The first stage's gain is externally con figurable, while the second stage's is internally fixed. The closed-loop gain of the first stage is set by selecting the ratio of Rf to R i while the second stage's gain is fixed at 2x.The output of amplifier 1 serves as the input to amplifier 2, thus the two amplifiers produce signals identical in magnitude, but different in phase by 180¡. Consequently, the differential gain for the IC is Input Capacitor (Ci ) Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain sized capacitor is needed to couple in low frequencies without severe attenu ation. But in many cases the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 100Hz to 150Hz. Thus, using a large input capacitor may not increase actual system perfor mance. In this case, input capacitor (C i ) and input resistance (R i) of the amplifier form a high-pass filter with the corner frequency determined by equation below, 1 f C= 2 Ri Ci A VD =20*log [2*(R f /R i )] T h e PA M 8 4 0 6 s e t s m a x i m u m R f = 1 4 2 k , minimum Ri =18k , so the maximum closed-gain is 24dB. Mode Selection When mode pin high,it features classD; mode pin low, it¡s class AB. Mode pin can¡t be floating. Mute Operation The MUTE pin is an input for controlling the output state of the PAM8406. A logic low on this pin disables the outputs, and a logic high on this pin enables the outputs. This pin may be used as a quick disable or enable of the outputs without a volume fade. Quiescent current is listed in the electrical characteristic table. The MUTE pin can be left floating due to the internal pull-up. In addition to system cost and size, click and pop perfor mance is affected by the size of the input coupling capacitor, C i. A larger input coupling capacitor requires more charge to reach its quiescent DC voltage (nominally 1/2 V DD ). This charge comes from the internal circuit via the feedback and is apt to create pops upo n device enable. Thus, by minimizing the capacitor size based on necessary low frequency response, turn-on pops can be minimized. Shutdown operation In order to reduce power consumption while not in use, the PAM8406 contains shutdown circuitry to turn off the amplifier's bias circuitry. This shutdown feature turns the amplifier off when logic low is applied to the SHDN pin. By switching the SHDN pin connected to GND, the PAM8406 supply current draw will be minimized in idle mode. The SHDN pin can be left floating due to the internal pull-up. Analog Reference Bypass Capacitor (C BYP ) The Analog Reference Bypass Capacitor (C BYP) is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, C BYP determines the rate at which the amplifie r sta rts up. Th e se cond function is to reduce noise caused by the power supply coupling into the output drive signal. This noise is from the internal analog reference to the amplifier, which appears as degraded PSRR and THD+N. Power supply decoupling The PAM8406 is a high performance CMOS audio amplifier that requires adequate power supply decoupling to ensure the output THD and P S R R a s l o w a s p o s s ib le . P o w e r s u p p l y decoupling affects low frequ ency response. Optimum decoupling is achieved by using two 11/2011 Rev1.0 10 PAM8406 Alternative 5W Stereo Audio Amplifier 11/2011 Rev1.0 11