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pam8803 document number: dsxxxxx rev. 1 - 4 1 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated 3w filterless stereo class-d audio amplifier with digital volume control description the pam8803 is a 3w, class-d audio amplifier with 64-step digital volume control. it offers low thd+n, allowing it to produce high- quality sound reproduction. the new f ilterless architecture allows the device to drive the speaker directly, without needing low-pass output filters which will save 30% system cost and 75% pcb area. with the same numbers of external components, the efficiency of the pam8803 is much better than class-ab cousins. it extends battery life, making it ideal for portable applications. the pam8803 is available in a ssop-24 package. features ? 3w output at 10% thd with a 4 ? load and 5v power supply ? filterless, low quiescent current and low emi ? low thd+n ? 64-step digital volume control ? superior low noise ? low pop noise ? efficiency up to 90% ? short circuit protection ? thermal shutdown ? few external components to save space and cost ? pb-free packages pin assignments applications ? lcd monitors/tv projectors ? notebook computers ? portable speakers ? portable dvd players, game machines ? cellular phones/speaker phones typical applications circuit
pam8803 document number: dsxxxxx rev. 1 - 4 2 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated pin descriptions pin number pin name function 1 -out_l left channel negative output 2 pgnd power gnd 3 pgnd power gnd 4 +out_l left channel positive output 5 pvdd power vdd 6 mute mute control input (active low), pull-up 7 vdd analog vdd 8 inl left channel input 9 nc no connect 10 vref internal analog reference, connect a bypass capacitor from vref to gnd 11 nc no connect 12 nc no connect 13 dn volume down control (active low) 14 up volume up control (active low) 15 rst volume controller reset (active low) 16 nc no connect 17 inr right channel input 18 gnd analog gnd 19 shdn shutdown control input (active low), pull-down 20 pvdd power vdd 21 +out_r right channel positive output 22 pgnd power gnd 23 pgnd power gnd 24 -out_r right channel negative output functional block diagram
pam8803 document number: dsxxxxx rev. 1 - 4 3 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated absolute maximum ratings (@t a = +25c, unless otherwise specified.) these are stress ratings only and functional operation is not im plied. exposure to absolute maximum ratings for prolonged time periods may affect device reliability. all voltages are with respect to ground. parameter rating unit supply voltage at no input signal 6.0 v input voltage -0.3 to v dd +0.3 maximum junction temperature 150 c storage temperature -65 to +150 soldering temperature 300, 5sec recommended operating conditions (@t a = +25c, unless otherwise specified.) parameter rating unit supply voltage range 2.2 to 5.5 v ambient temperature range -40 to +85 c junction temperature range -40 to +125 c thermal information parameter package symbol max unit thermal resistance (junction to ambient) ssop-24 ja 96 c/w
pam8803 document number: dsxxxxx rev. 1 - 4 4 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated electrical characteristics (@t a = +25c, v dd = 5v, gain = 18db, r l = 8 ? , unless otherwise specified.) parameter symbol test conditions min typ max units supply voltage range v dd 2.2 5.5 v quiescent current i q no load 7 15 ma r l = 8 ? 8 r l = 4 ? 8.5 mute current i mute v mute = 0v 2.5 4 ma shutdown current i shdn v shdn = 0v 0.5 10 a shdn input high v sh 1.2 v shdn input low v sl 0.5 mute input high v mh 1.2 v mute input low v ml 0.5 output offset voltage v os no load 120 300 mv drain-source on-state resistance r ds(on) i ds = 0.5a pmosfet 0.3 0.40 ? n mosfet 0.22 0.35 output power p o f =1khz r l = 8 ? , thd =1% 1.1 1.3 w r l = 8 ? , thd = 10% 1.5 1.7 r l = 4 ? , thd = 1% 1.9 2.1 r l = 4 ? , thd = 10% 2.8 3.0 total harmonic distortion plus noise thd+n r l = 8 ? , p o = 0.5w 0.19 % r l = 8 ? , p o = 1.0w 0.22 r l = 4 ? , p o = 1.0w 0.17 r l = 4 ? , p o = 2.0w 0.25 power supply ripple rejection psrr no input, f = 1khz, v pp = 200mv 45 55 db channel separation cs p o = 1w, r l = 4 ? 60 80 db oscillator frequency f osc 170 210 250 khz efficiency p o = 1.7w, f = 1khz, r l = 8 ? 85 89 % p o = 3.0w, f = 1khz, r l = 4 ? 80 83 % signal noise ratio snr f = 22 to 22khz thd = 1% r l = 4 ? 85 db r l = 8 ? 87 db under voltage lock-out uvlo 1.95 v over temperature protection otp 150 c over temperature hysteresis oth 60 c
pam8803 document number: dsxxxxx rev. 1 - 4 5 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated typical performance characteristics (@t a = +25c, unless otherwise specified.)
pam8803 document number: dsxxxxx rev. 1 - 4 6 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated typical performance characteristics (cont.) (@t a = +25c, unless otherwise specified.)
pam8803 document number: dsxxxxx rev. 1 - 4 7 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated typical performance characteristics (cont.) (@t a = +25c, unless otherwise specified.) gain setting (v dd = 5v) step gain (db) step gain (db) step gain (db) step gain (db) 1 -75.0 17 4.8 33 11.2 49 17.6 2 -39.7 18 5.1 34 11.6 50 18.0 3 -34.0 19 5.5 35 12.0 51 18.4 4 -28.2 20 5.9 36 12.3 52 18.8 5 -22.4 21 6.3 37 12.7 53 19.2 6 -16.5 22 6.7 38 13.2 54 19.6 7 -10.5 23 7.1 39 13.6 55 20.0 8 -8.0 24 7.5 40 14.0 56 20.4 9 -5.5 25 7.9 41 14.4 57 20.9 10 -2.9 26 8.3 42 14.8 58 21.3 11 -0.4 27 8.7 43 15.2 59 21.7 12 1.1 28 9.1 44 15.6 60 22.1 13 2.6 (note 1) 29 9.6 45 16.0 61 22.5 14 3.6 30 10.0 46 16.4 62 22.9 15 4.0 31 10.4 47 16.8 63 23.4 16 4.4 32 10.7 48 17.2 64 23.8 note: 1.power on gain or gain after reset. gain could have 1db deviation device to device.
pam8803 document number: dsxxxxx rev. 1 - 4 8 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated application information maximum gain as shown in block diagram (page 2),the pam8803 has two internal amplifiers stage. the first stage's gain is externally configur able, while the second stage's is internally fixed in a fi xed-gain, inverting configuration. the cl osed-loop gain of the first stage is set by selecting the ratio of r f to r j while the second stage's gain is fixed at 2x. consequently, the differential gain for the ic is: a vd = 20*log [2*(r f /r j )] the pam8803 sets maximum r f = 218k ? minimum r j = 27k ? , thus the maximum closed gain is 24db. digital volume control (dvc) the pam8803 features a digital volume control which consists of the up, dn and rst pins. an internal clock is used where the cl ock frequency value is determined from the following formula: f clk = f osc /2 13 the oscillator frequency f osc value is 200khz typical, with 20% tolerance.t he dvc?s clock frequency is 33hz (cycle time) typical. volume changes are then effected by toggling either the up or dn pins with a logic low. after a period of 3.5 clocks pulses wit h either the up or dn pins held low, the volume will change to the next specified st ep, either up or dn, and followed by a short delay. this delay decreases the longer the line is held low, eventually reaching a delay of zero. th e delay allows the user to pull the up or dn terminal low o nce for one volume change, or hold down to ramp several volume changes. the delay is optimally configured for push button volume control. if either the up or dn pin remains low after the first volume transition the volume will change again, but this time after 9.5 clock pulses. the followed transition occurs at 2 clock pulses for each volume trans ition. this is intended to provide the user with a volume con trol that pauses briefly after initial application, and then slowly increases the ra te of volume change as it is continuously applied. this cycl e is shown in the timing diagram shown in figure 1. there are 64 discrete gain settings ranging from +24db maximum to -75db minimum. upon device power on or applied a logic low to the rst pin, the amplifier's gain is set to a default value of 2.6db. however, when coming out of mute mode, the pam8803 will revert ba ck to its previous gain setting. volume levels for each step vary an d are specified in gain setting table on page 7. if both the up and dn pins are held high, no volume change will o ccur. trigger points for the up and dn pins are at 70% of v dd minimum for a logic high, and 20% of v dd maximum for a logic low. it is recommended, however, to toggle up and dn between v dd and gnd for best performance. figure 1.timming diagram mute operation the mute pin is an input for controlling the output state of t he pam8803. a logic low on this pi n disables the outputs, and a l ogic 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 pull-up internal. shutdown operation in order to reduce power consumption while not in use, the pam 8803 contains shutdown ci rcuitry that is used to turn off the amp lifier's bias circuitry. this shutdown feature turns the amplifier off when logic low is placed on the shdn pi n. by switching the shdn pin co nnected to gnd, the pam8803 supply current draw will be minimized in idle mode. the shdn pin cannot be left floating due to the pull-down inter nal.
pam8803 document number: dsxxxxx rev. 1 - 4 9 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated application information (cont.) power supply decoupling the pam8803 is a high performance cmos audio amplifier that r equires adequate power supply decoupling to ensure the output thd and psrr are as low as possible. power supply decoupling is affecting low frequency respons e. optimum decoupling is achieved by usi ng two capacitors of different types that target different types of noise on the power supply leads. for higher frequency transients, spikes, or digital hash on the line, a good low equivalent-seriesresis tance (esr) ceramic capacitor, typically 1.0 f, placed as close as possible to the device v dd terminal works best. for filtering lowerfrequency noise signals, a larger capacitor of 10f (cer amic) or greater placed near th e audio power amplifier is recommended. input capacitor (c j ) large input capacitors are both expensive and space hungry for portable des igns. clearly, a certain sized capacitor is needed t o couple in low frequencies without severe attenu ation. but in many cases the sp eakers 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 performance. in t his case, input capacitor (c j ) and input resistance (r j ) of the amplifier form a high-pass filter with the corner frequency determined equation below, c r 2 1 f j j c ? ? in addition to system cost and size, click and pop performance is affected by the size of the input coupling capacitor, c j . 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 upon device enable. thus, by mi nimizing the capacitor size ba sed on necessary low frequency response, turn-on pops can be minimized. analog reference bypass capacitor (c byp ) the analog reference bypass capacitor (c byp ) is the most critical capacitor and serves severa l important functions. during start-up or recovery from shutdown mode, c byp determines the rate at which the amplifier starts up. t he second function is to reduce noise produced by the power supply caused by coupling into the output dr ive signal. this noise is from the inter nal analog reference to the amplifier, whic h appears as degraded psrr and thd+n. bypass capacitor (c byp ) values of 0.47 f to 1.0 f ceramic is recommended for the best thd and noise performance. increasing the bypass capacitor reduces clicking and popping noise from power on/off and entering and leaving shutdown. under voltage lock-out (uvlo) the pam8803 incorporates circuitry designed to detect when the s upply voltage is low. when the supply voltage drops to 1.85v or below, the pam8803 outputs are disable, and the device comes out of this stat e and starts to normal functional when the supply voltage inc reases. short circuit protection (scp) the pam8803 has short circuit protection ci rcuitry on the outputs that prevents damage to the device during output-to-output an d output-to- gnd short. when a short circuit is detected on t he outputs, the outputs are disable immediat ely. if the short was removed, the devi ce activates again. over temperature protection thermal protection on the pam8803 prevents damage to the device when the internal die temperature exceeds +150c. there is a 15 degree tolerance on this trip point from device to device. once the die temperature exceeds the thermal set point, the device outputs are disabled. this is not a latched fault. the thermal fault is cleared once the temper ature of the die is reduced by +60c. this large hysteresis will prevent motor boating sound well and the device begins normal operation at th is point with no external system interaction. how to reduce emi (electro magnetic interference a simple solution is to put an additional capacitor 1000f at po wer supply terminal for power li ne coupling if the traces from amplifier to speakers are short (<20cm).
pam8803 document number: dsxxxxx rev. 1 - 4 10 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated application information (cont.) how to reduce emi (electro magnetic interference most applications require a ferrite bead filter which shows at figure 3. the ferrite filter reduces emi around 1 mhz and higher . when selecting a ferrite bead, choose one with high impedance at high frequencies, but low impedance at low frequencies. figure 3. ferrite bead filter to reduce emi pcb layout guidelines grounding at this stage it is paramount t h a t we acknowledge the need for separate grounds. noise currents in the output power stage ne ed to be returned to output noise ground and nowhere else. were these currents to circulate elsewhere, they may get into the power supply, the si gnal ground, etc, worse yet, they may form a loop and radiate noise. any of thes e instances results in degraded amplifier performance. the logica l returns for the output noise currents associated with class d switching are the respective pgnd pins for each c hannel. the switch state diagram illustrates that pgnd is instrumental in nearly every switch state. this is t he perfect point to which the output noise ground trace should retu rn. also note that output noise ground is channel specific. a two channels amplifier has two mutually exclusive c hannels and consequently must hav e two mutually exclusive output noise ground traces. the layout of the pam8803 o ffers separate pgnd connections fo r each channel and in some c ases each side of the bridge. output noise grounds must tie to system gr ound at the power in exclusively. signal currents for the inputs, reference, etc need to be returned to quite ground. this ground only ties to the si gnal components and the gnd pin. gnd then ties to system ground. power supply line as same to the ground, v dd and each channel pv dd need to be separated and tied together at the system power supply. recommend that all the trace could be routed as short and thick as possible. for the power line layout, just imagine water stream, any barricade p laced in the trace (shows in figure 4) could result in the bad performance of the amplifier. figure 4 componemts placement the power supply decoupling capacitor s need to be placed as close to v dd and pv dd pins as possible. the inputs need to be routed away from the noisy trace. the v ref bypass capacitor also needs to be close to the pin of ic very much. pcb top layer pcb bottom layer figure 5. layout example
pam8803 document number: dsxxxxx rev. 1 - 4 11 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated application notice 1. when pam8803 works without filter, we must connect the speak er before turn on. else, it will be easy to damage the chip. 2. when pam8803 works without filter, it will be best that addi ng a ferrite chip bead at the outgoing line of speaker in order to suppress possible electromagnetic interference . 3. the absolute maximum rating of operation voltage is 6.0v. while using 6v power regulator, even the chip can deliver 4w sine wave with a 4 ? speaker, it is not recommended for l ong term using due to the heat dissipation. bu t if the input signal is a music signal, then it can work in long term since the average power output is much less than 4w. when using dry battery cell, we should notice that if the battery cell is 4 new dry batteries or alkaline batteries, ev en the voltage will be over 6v, it still can work safety. since the output voltage of th e 4 pack of new dry batteries will be reduced very quickly after turn on due to the internal resistance of the battery. there is no dangerous o f damaging the chip when playing music or speech, even us e 4 new dry batteries. to reduce the effect of the increasing of internal resistance o f battery after long term discharging, it is recomm ended to connect a 1000f electrol ytic capacitor between the power supply and the ground. 4. because digital volume control has big gain, we can not make input signal too hi gh to cause the clipping of the output signa l when increase volume, also it may damage the chip. test setup for application testing notes: 2. the ap aux-0025 low pass filter is necessary fo r every class-d amplifier measurement done by ap analyzer. 3. two 22 h inductors are used in series with load resistor to emulate the small speaker fo r efficiency and quiescent current measurement.
pam8803 document number: dsxxxxx rev. 1 - 4 12 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated ordering information part number part marking package type standard package PAM8803NHR pam8803 xxxywwll ssop-24 2500 units/tape&reel marking information
pam8803 document number: dsxxxxx rev. 1 - 4 13 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated package outline dimensions (all dimensions in mm.) ssop-24
pam8803 document number: dsxxxxx rev. 1 - 4 14 of 14 www.diodes.com november 2012 ? diodes incorporated pam8803 a product line o f diodes incorporated important notice diodes incorporated makes no warranty of any kind, express or implied, with regards to this document, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries rese rve the right to make modifications, enhanc ements, improvements, corrections or ot her changes without further notice to this document and any product descri bed herein. diodes incorporated does not assume any liability ari sing out of the application or use of this document or an y product described herein; neither does di odes incorporated convey any license under its patent or trademark rights, nor the rights of others. any customer or us er of this document or products described herein in such applica tions shall assume all risks of such use and will agree to hold diodes incorporated a nd all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability w hatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes inco rporated products for any unintended or una uthorized application, customers shall i ndemnify and hold diodes incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death a ssociated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or foreign patents pending. product names and markings noted herein may also be covered by one or more united states, international or foreign trademarks. this document is written in english but may be translated into multiple languages for reference. only the english version of t his document is the final and determinative format released by diodes incorporated. life support diodes incorporated products are specifically not authorized for use as critical component s in life support devices or systems without the express written approval of the chief executive offi cer of diodes incorporated. as used herein: a. life support devices or syst ems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when proper ly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support devic e or system whose failure to perform can be reasonably expect ed to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifi cations of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-rel ated requirements concerning the ir products and any use of diodes incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or s ystems-related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporate d and its representatives against any damages arisi ng out of the use of diodes incorporated pr oducts in such safety-critical, life suppor t devices or systems. copyright ? 2012, diodes incorporated www.diodes.com

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