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general description the MAX98307/max98308 fully differential mono class dg multilevel power amplifiers with integrated inverting charge pumps offer highly efficient, high-power audio solutions for portable applications. class dg multilevel modulation extends the dynamic range of the output signal by employing a charge-pump - generated negative rail as needed to extend the supply range. this scheme results in high efficiency over a wide output power range. the ics combine maxims active emissions limiting edge rate and overshoot control circuitry with multilevel output modulation to greatly reduce emi. these features elimi - nate the need for output filtering as compared to tradition - al class d devices, reducing component count and cost. the MAX98307s 16-pin tqfn package features an adjustable gain set by external resistors. the max98308s space-saving 12-bump wlp package features an inter - nally fixed gain of 8.5db, 11.5db, 14.5db, 17.5db, and 20.5db set by a single gain input. both devices operate over the extended -40c to +85c temperature range. applications beneits and features high efficiency combined with high output power ? class dg multilevel modulation ensures maximum eficiency over wide output power range improves battery life ? low 1.85ma quiescent current high output power at 1% thd+n ? 1.54w at v pvdd = 3.6v, 8 + 68h load ? 2.85w at v pvdd = 5v, 8 + 68h load high output power at 10% thd+n ? 1.77w at v pvdd = 3.6v, 8 + 68h load ? 3.3w at v pvdd = 5v, 8 + 68h load 84% efficiency (v pvdd = 3.6v, at 500mw output) active emissions limiting and class dg multilevel output modulation eliminates emi output filtering requirement integrated charge pump and high efficiency results in small solution size excellent rf immunity click-and-pop suppression thermal and overcurrent protection low-current shutdown mode ordering information appears at end of data sheet. 19-5848; rev 6; 6/16 cellular phones smartphones notebook computers voip phones portable audio tablet pcs pvddgnd fb- fb+ in- in+ shdn pvss pgnd svss c1pc1n out+ out- v cc charge pump class dg amplifier MAX98307 pvdd gnd in- in+ shdn pvss pgnd c1pc1n out+ out- gain charge pump class dg amplifier max98308 simpliied block diagrams MAX98307/max98308 3.3w mono class dg multilevel audio amplifier evaluation kit available downloaded from: http:///
pvddgnd fb- fb+ 20k ? 20k ? 10k ? 0.33f0.33f 10k ? 12 1 7 13 3 14 1615 45 8 6 2 1110 9 *system bulk capacitor in- in+ shdn svss pvss pgnd c1pc1n out+ out- n.c. v cc 10f* 10f 4.7f 0.1f 2.6v to 5.25 charge pump class dg amplifier MAX98307 0.1f pvddgnd gain b3 0.33f0.33f b2 a3 c1 a1b1 a4 b4 c4 a2 c3 c2 *system bulk capacitor in- in+ shdn pvss pgnd c1pc1n out+ out- 10f* 10f 4.7f 0.1f 2.6v to 5.25 charge pump class dg amplifier max98308 MAX98307 typical application circuit max98308 typical application circuit MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 2 downloaded from: http:///
pvdd to gnd ......................................................... -0.3v to +6v pgnd to gnd ...................................................... -0.3v to +0.3v c1n to gnd ......................................... (v pvss - 0.3v) to +0.3v in+, in- (MAX98307) ................................ -0.3v to (v cc + 0.3v) v cc to pvdd (MAX98307) .................................. -0.3v to +0.3v pvss to svss (max97307) ................................ -0.3v to +0.3v pvss, svss to gnd (MAX98307) ......................... -6v to +0.3v in+, in- (max98308) ............................................... -0.3v to +6v pvss to gnd (max98308) .................................... -6v to +0.3v all other pins to gnd .......................... -0.3v to (v pvdd + 0.3v) continuous current into/out of pvdd, v cc , pgnd, gnd, out+, out-, c1p, c1n, pvss, svss ...................... 800ma continuous current (all other pins) .................................. 20ma duration of out+/out- short circuit to pgnd or pvdd ................................................................ continuous short-circuit duration between out+ and out- pins ............................................ continuous continuous power dissipation (t a = +70c) for multilayer board tqfn (derate 20.8mw/c above +70c) ..................1667mw wlp (derate 13.7mw/c above +70c) .................... 1100mw junction temperature ...................................................... +150c operating temperature range ........................... -40c to +85c storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) (tqfn-ep) .............. +300c soldering temperature (reflow) ....................................... +260c tqfn junction-to-ambient thermal resistance ( ja ) .......... 48c/w junction-to-case thermal resistance ( jc ) ............... 10c/w wlp junction-to-ambient thermal resistance ( ja ) .......... 73c/w junction-to-case thermal resistance ( jc ) ............... 30c/w (note 1) (v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-. [MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k] c in+ = c in- = 0.33f, a v = 14.5db, ac measurement bandwidth 20hz to 20khz, t a = t min to t max , unless otherwise noted. typical values are at t a = +25c.) (notes 2, 3) note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . absolute maximum ratings 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 of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. package thermal characteristicselectrical characteristics parameter symbol conditions min typ max units power-supply range v pvdd , v cc guaranteed by psrr test 2.6 5.25 v quiescent current i dd v pvdd = 3.6v 1.85 2.7 ma shutdown current i shdn shdn = gnd 0.225 10 a power-supply rejection ratio (note 4) psrr v pvdd = 2.6v to 5.25v 78 db f = 217hz, 200mv p-p ripple 78 f = 10khz, 200mv p-p ripple 67 turn-on time t on time from shutdown or power-on to full operation max98308 25 40 ms MAX98307, r in = 10k? 50 80 input dc bias voltage v bias 1.3 v input resistance (max98308) r in a v = 20.5db (maximum gain) 15 22 k? a v = 17.5db 22 a v = 14.5db 22 a v = 11.5db 28 a v = 8.5db 40 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 3 downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-. [MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k] c in+ = c in- = 0.33f, a v = 14.5db, ac measurement bandwidth 20hz to 20khz, t a = t min to t max , unless otherwise noted. typical values are at t a = +25c.) (notes 2, 3) electrical characteristics (continued) parameter symbol conditions min typ max units voltage gain (max98308) a v gain = short to gnd 20 20.5 21 db gain = 100k? pulldown to gnd 17 17.5 18 gain = short to pvdd 14 14.5 15 gain = 100k? pullup to pvdd 11 11.5 12 gain = unconnected 8 8.5 9 common-mode rejection ratio (max98308) cmrr f in = 1khz 65 db output power (MAX98307) p out f in = 1khz, thd+n = 1% z l = 8? + 68h, v pvdd = 3.6v 1.54 w z l = 8? + 68h, v pvdd = 4.2v 2 z l = 8? + 68h, v pvdd = 5.0v 2.85 f in = 1khz, thd+n = 10% z l = 8? + 68h, v pvdd = 3.6v 1.77 z l = 8? + 68h, v pvdd = 4.2v 2.3 z l = 8? + 68h, v pvdd = 5.0v 3.3 output power (max98308) p out thd+n 1% z spk = 8? + 68h, v pvdd = 3.6v 1.4 w z spk = 8? + 68h, v pvdd = 4.2v 1.92 z spk = 8? + 68h, v pvdd = 5.0v 2.7 thd+n 10% z spk = 8? + 68h, v pvdd = 3.6v 1.57 z spk = 8? + 68h, v pvdd = 4.2v 2.13 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 4 downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-. [MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k] c in+ = c in- = 0.33f, a v = 14.5db, ac measurement bandwidth 20hz to 20khz, t a = t min to t max , unless otherwise noted. typical values are at t a = +25c.) (notes 2, 3) note 2: 100% production tested at t a = +25c. specifications over temperature limits are guaranteed by design. note 3: testing performed with a resistive load in series with an inductor to simulate an actual speaker. fo r r l = 8 , l = 68h. note 4: amplifier inputs ac-coupled to gnd. note 5: specified at room temperature with an 8 resistive load in series with a 68h inductive load connect ed across the btl outputs. mode transitions controlled by shdn active-low shutdown control. electrical characteristics (continued) parameter symbol conditions min typ max units total harmonic distortion plus noise thd+n f in = 1khz, p out = 1w 0.05 % output offset voltage v os t a = +25c 1 5 mv click-and-pop level k cp peak voltage, a-weighted, 32 samples per second (notes 4, 5) into shutdown -65 dbv out of shutdown -65 output switching frequency 340 khz efficiency f in = 1khz, p out at 500mw, thd+n = 0.02% 84 % f in = 1khz, p out at 1w, thd+n = 0.05% 82 current limit i lim 2 a rms output noise v n a-weighted 52 v rms logic input ( shdn ) input voltage high v ih 1.4 v input voltage low v il 0.4 v input leakage current t a = +25c 10 a MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 5 downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics total harmonic distortion plus noise vs. output power (MAX98307) MAX98307 toc01 output power (w) 2.0 1.5 1.0 0.5 0 2.5 thd+n (%) 0.01 0.1 1 10 100 0.001 v pvdd = 3.6v f in = 1khz f in = 100hz f in = 6khz total harmonic distortion plus noise vs. output power (max98308) MAX98307 toc04 output power (w) 2.0 1.5 1.0 0.5 0 2.5 thd+n (%) 0.01 0.1 1 10 100 0.001 v pvdd = 3.6v f in = 1khz f in = 100hz f in = 6khz total harmonic distortion plus noise vs. output power (MAX98307) MAX98307 toc02 output power (w) 3.0 2.5 2.0 1.5 1.0 0.5 0 3.5 thd+n (%) 0.01 0.1 10 100 0.001 1 v pvdd = 4.2v f in = 1khz f in = 100hz f in = 6khz MAX98307 toc05 2.5 2.0 1.5 1.0 0.5 0 3.0 thd+n (%) 0.01 0.1 10 100 0.001 1 total harmonic distortion plus noise vs. output power (max98308) v pvdd = 4.2v f in = 1khz f in = 100hz f in = 6khz output power (w) total harmonic distortion plus noise vs. output power (MAX98307) MAX98307 toc03 output power (w) 4 3 2 1 0 5 thd+n (%) 0.01 0.1 1 10 100 0.001 v pvdd = 5v f in = 1khz f in = 100hz f in = 6khz MAX98307 toc06 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 4.0 thd+n (%) 0.01 0.1 10 100 0.001 1 total harmonic distortion plus noise vs. output power (max98308) v pvdd = 5v f in = 1khz f in = 100hz f in = 6khz output power (w) MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 6 www.maximintegrated.com downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics (continued) MAX98307 toc07 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (MAX98307) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 3.6v p out = 300mw p out = 1.3w MAX98307 toc10 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (max98308) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 3.6v p out = 300mw p out = 1.1w MAX98307 toc08 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (MAX98307) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 4.2v p out = 500mw p out = 1.6w MAX98307 toc11 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (max98308) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 4.2v p out = 500mw p out = 1.6w MAX98307 toc09 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (MAX98307) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 5v p out = 700mw p out = 2.4w MAX98307 toc12 0.01 0.1 1 10 0.001 10 total harmonic distortion plus noise vs. frequency (max98308) frequency (khz) thd+n (%) 10k 1k 100 100k v pvdd = 5v p out = 700mw p out = 2.4w MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 7 www.maximintegrated.com downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics (continued) output power vs. load resistance (MAX98307) MAX98307 toc13 load resistance ( ? ) output power (w) 100 10 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0 1 1k v pvdd = 3.6v f in = 1khz thd+n = 1% thd+n = 10% MAX98307 toc16 0.2 0.6 0.8 0 1.0 1.2 1.4 1.6 0 output power (w) load resistance ( ? ) 100 10 1 1k v pvdd = 3.6v f in = 1khz thd+n = 1% thd+n = 10% output power vs. load resistance (max98308) output power (w) 0.5 1.0 1.5 2.0 2.5 0 MAX98307 toc14 load resistance ( ? ) 100 10 1 1k v pvdd = 4.2v f in = 1khz thd+n = 1% thd+n = 10% output power vs. load resistance (MAX98307) output power vs. load resistance (max98308) load resistance ( ? ) output power (w) 100 10 0.5 1.0 1.5 2.0 2.5 0 1 1k thd+n = 10% thd+n = 1% MAX98307 toc17 v pvdd = 4.2v f in = 1khz MAX98307 toc15 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 output power (w) load resistance ( ? ) 100 10 1 1k v pvdd = 5v f in = 1khz thd+n = 1% thd+n = 10% output power vs. load resistance (MAX98307) output power vs. load resistance (max98308) load resistance ( ? ) output power (mw) 100 10 1 1k thd+n = 10% thd+n = 1% MAX98307 toc18 v pvdd = 5v f in = 1khz 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 8 www.maximintegrated.com downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics (continued) output power vs. supply voltage (MAX98307) MAX98307 toc19 supply voltage (v) output power (w) 5.0 4.6 3.0 3.4 3.8 4.2 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 2.6 5.4 thd+n = 10% thd+n = 1% f in = 1khz efficiency vs. output power (MAX98307) MAX98307 toc22 output power (w) efficiency (%) 1.0 0.8 0.6 0.4 0.2 10 20 30 40 50 60 70 80 90 0 0 1.2 v pvdd = 3.6v f in = 1khz output power vs. supply voltage (max98308) MAX98307 toc20 supply voltage (v) output power (w) 5.0 4.6 4.2 3.8 3.4 3.0 0.5 1.0 1.5 2.0 3.0 2.5 3.5 0 2.6 5.4 f in = 1khz thd+n = 1% thd+n = 10% thermally limited efficiency vs. output power (MAX98307) MAX98307 toc23 output power (w) efficiency (%) 10 20 30 40 50 60 70 80 90 0 v pvdd = 4.2v f in = 1khz 1.4 1.2 0.8 1.0 0.4 0.6 0.2 0 1.6 gain vs. frequency (max98308) MAX98307 toc21 frequency (khz) amplitude (db) 10k 1k 100 -10 0 10 20 30 -20 10 100k gain = unconnected gain = 100k ? to v pvdd gain = pgnd gain = v pvdd gain = 100k ? to pgnd efficiency vs. output power (MAX98307) MAX98307 toc24 output power (w) efficiency (%) 10 20 30 40 50 60 70 80 90 0 v pvdd = 5v f in = 1khz 2.0 1.5 1.0 0.5 0 2.5 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 9 www.maximintegrated.com downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics (continued) efficiency vs. output power (max98308) MAX98307 toc25 output power (w) efficiency (%) 1.0 0.8 0.6 0.4 0.2 10 20 30 40 50 60 70 80 90 0 0 1.2 v pvdd = 3.6v f in = 1khz supply current vs. supply voltage MAX98307 toc28 supply voltage (v) supply current (ma) 5.0 4.5 4.0 3.5 3.0 0.5 1.0 1.5 2.0 2.5 3.0 0 2.5 5.5 v pvdd = 3.6v f in = 1khz efficiency vs. output power (max98308) MAX98307 toc26 output power (w) efficiency (%) 10 20 30 40 50 60 70 80 90 0 v pvdd = 4.2v f in = 1khz 1.4 1.2 0.8 1.0 0.4 0.6 0.2 0 1.6 shutdown current vs. supply voltage MAX98307 toc29 supply voltage (v) shutdown current (na) 5.0 4.5 3.0 3.5 4.0 50 100 150 200 250 300 350 400 0 2.5 5.5 efficiency vs. output power (max98308) MAX98307 toc27 output power (w) efficiency (%) 10 20 30 40 50 60 70 80 90 0 v pvdd = 5v f in = 1khz 2.0 1.5 1.0 0.5 0 2.5 power-supply rejection ratio vs. frequency MAX98307 toc30 frequency (hz) psrr (db) 10k 1k 100 -80 -70 -60 -50 -40 -30 -20 -10 0 -90 10 100k v ripple = 200mv p-p MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 10 www.maximintegrated.com downloaded from: http:///
(v pvdd = v cc = v shdn = 3.6v, v pgnd = v gnd = 0v, z l = 8 + 68h between out+ and out-, a v = 14.5db (MAX98307 r in+ = r in- = 10k, r fb+ = r fb- = 20k), c in+ = c in- = 0.33f, ac measurement bandwidth 20hz to 20khz.) typical operating characteristics (continued) startup response MAX98307 toc33 i speaker 100ma /div 20ms/div v shdn 2v/div shutdown response MAX98307 toc34 i speaker 100ma /div 20ms/div v shdn 2v/div common-mode rejection ratio vs. frequency (MAX98307) MAX98307 toc31 frequency (hz) cmrr (db) 10k 1k 100 -80 -70 -60 -50 -40 -30 -20 -10 0 -90 10 100k f in = 1khz common-mode rejection ratio vs. frequency (max98308) MAX98307 toc32 frequency (hz) cmrr (db) 10k 1k 100 -70 -60 -50 -40 -30 -20 -10 0 -80 10 100k wideband vs. frequency MAX98307 toc35 frequency (hz) output magnitude (dbv) 10g 1g -160 -140 -120 -100 -80 -60 -40 -20 0 -180 100k 100g v pvdd = 3.6v inband output spectrum MAX98307 toc36 frequency (hz) output magnitude (dbv) 10k 1k 100 -120 -100 -80 -60 -40 -20 0 -140 10 100k v pvdd = 3.6v clipping waveform 10% thd+n MAX98307 toc37 out-1v/div 200s/div out+1v/div MAX98307/max98308 3.3w mono class dg multilevel audio ampliier maxim integrated 11 www.maximintegrated.com downloaded from: http:///
pin/bump description pin/bump conigurations 1516 14 13 65 7 gnd out+ 8 in+fb- fb+ 1 2 pvss 4 12 11 9 c1n c1p ep n.c.svss pgnd out- + pvdd in- 3 10 v cc tqfn MAX98307 top view top view (bumps side down) wlp pgnd pvss out- c1n max98308 + 1 2 3 4 a in+ in- gain b c shdn shdn out+ c1p gnd pvdd pin bump name function MAX98307 max98308 1 b2 shdn active-low shutdown. connect to gnd for shutdown. connect to pvdd for normal operation. 2 a2 gnd substrate and signal ground 3 a3 pvdd power and charge-pump supply. bypass to pgnd with a 0.1f capacitor. 4 a4 out+ positive ampliier output 5 b4 out- negative ampliier output 6 c4 pgnd power ground 7 svss ampliier negative power supply. connect to pvss (MAX98307). 8 n.c. no connection. not internally connected. connect to gnd or leave unconnected. 9 fb- negative ampliier feedback 10 c3 in- negative ampliier input 11 c2 in+ positive ampliier input 12 fb+ positive ampliier feedback b3 gain see table 1 max98308 gain coniguration for more information. 13 v cc signal supply 14 c1 pvss charge-pump output. connect a 10f capacitor between pvss and pgnd. 15 b1 c1n charge-pump flying capacitor negative terminal. connect a 4.7f capacitor between c1n and c1p. 16 a1 c1p charge-pump flying capacitor positive terminal. connect a 4.7f capacitor between c1n and c1p. ep exposed pad (tqfn only). internally connected to gnd. connect to a large ground plane with multiple vias to maximize thermal performance. not intended as an electrical connection point. MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 12 downloaded from: http:///
detailed description the MAX98307/max98308 fully differential mono class dg multilevel power amplifiers with integrated inverting charge pumps offer highly efficient, high-power audio solutions for portable applications. the new class dg multilevel modulation scheme extends the dynamic range of the output signal by employing a charge-pump-generated negative rail, which is used as needed to extend the supply range. when the negative rail is not needed, the output is drawn entirely from the standard supply. this scheme results in high efficiency over a wide output power range. the power amplifier incorporates active emissions limiting edge rate and overshoot control circuitry in combination with the multilevel output modulation scheme to greatly reduce emi. these features eliminate the need for output filtering as compared to traditional class d amplifiers, which reduces an applications component count. the MAX98307 has an adjustable gain set by external resistors. the max98308 has preset fixed gains of 8.5db, 11.5db, 14.5db, 17.5db, and 20.5db set by a gain select input (gain). class dg multilevel operation the ics filterless class dg multilevel amplifiers feature a proprietary maxim output stage that offers higher effi - ciency over a greater output power range than previous amplifiers. the amplifier combines class d switching output efficiency and class g supply level shifting with a multilevel output modulation scheme that with a 5v supply has efficiency better than 80% efficiency over the 0.35w to 2.2w output range. the class dg multilevel output stage uses pulse-width modulation (pwm), a rail-to-rail digital output signal with variable duty cycle, to approximate an analog input signal as in a class d amplifier. rail-to-rail operation ensures that any dissipation at the output is due solely to the r ds(on) of the power output mosfets. the class dg multilevel output stage also senses the magnitude of the output signal and switches the supply rails as needed to more efficiently supply the required signal power. for a low output signal swing requirement (below the bat - tery supply rail v pvdd ), the output range is between v pvdd and ground. when output swing above v pvdd is required, v pvss , an internal inverting charge-pump- generated negative rail replaces ground as the lower sup - ply. the high output swing range is then v pvdd to v pvss , approximately double the low swing range. this approach efficiently manages power consumption by switching the operating rails as needed according to the output swing requirements. additionally, multilevel output modulation is employed in to draw the maximum possible power from the lower impedance battery supply rail, v pvdd , rather than the higher impedance charge-pump-generated rail v pvss . this is accomplished by generating pwm sig - nals that swing from ground to v pvdd or from ground to v pvss at either end of the bridge tied load (btl) rather than continually swinging from v pvdd to v pvss . the sig - nals are modulated in such a way that v pvss is used only as necessary to generate low-end signal swing. these combined operations ensure that power dissipation due to r ds(on) loss and charge-pump impedance is min - imized, and that efficiency and output power is maximized across the audio range. class dg multilevel operation is shown as figure 1 . figure 1. class dg multilevel operation MAX98307 fig01 400s /div out+5v/div out- 5v/div out+ - out- 10v/div MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 13 downloaded from: http:///
the class dg multilevel efficiency compares favor - ably with class ab and class g amplifiers as shown in figure 2 . note that efficiency at 1w is 85%. emi filterless output stage traditional class d amplifiers require the use of external lc filters, or shielding, to meet electromagnetic-interfer - ence (emi) regulation standards. the active emissions limiting edge-rate control circuitry and class dg multilevel modulation scheme reduce emi emissions without the need for external filtering components, while maintaining high efficiency (see figure 3 ). ampliier current limit if the output current of the speaker amplifier exceeds the current limit, the ics disable the outputs for approximately 100s. after 100s, the outputs are reenabled. if the fault condition still exists, the ics continue to disable and reen - able the outputs until the fault condition is removed. figure 2. class dg multilevel vs. typical class g and class ab amplifier efficiency figure 3. emi performance with v pvdd = 5v, 12in of speaker cable, no output filter efficiency vs. output power output power (w) efficiency (%) 1.8 1.6 1.2 1.4 0.4 0.6 0.8 1.0 0.2 10 20 30 40 50 60 70 80 90 0 0 2.0 MAX98307/max98308 class dg multilevel amplifier class ab amplifier class g amplifier v pvdd = 5v f in = 1khz 100 0 -10 10 30 50 70 90 200 300 400 500 en55022b limit horizontal vertical 600 700 800 900 1000 frequency (mhz) emissions level (dbv/m) MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 14 downloaded from: http:///
click-and-pop suppression the speaker amplifier features maxims comprehensive click-and-pop suppression. during startup, the click-and- pop suppression circuitry reduces any audible transient sources internal to the device. when entering shutdown, the differential speaker outputs quickly and simultane - ously ramp down to pgnd.thermal and short circuit protection the ics automatically enter thermal shutdown when the die temperature is greater than +160c and reactivate at less than +135c. additionally, if the outputs are shorted to each other or either rail, the amplifier prevents cata - strophic loss by disabling the outputs. shutdown the ics feature a low-power shutdown mode, drawing less than 0.225a (typ) supply current. drive shdn low to put the ic into the shutdown state. applications information filterless class dg operation traditional class dg amplifiers require an output filter. the filter adds cost and size, as well as decreases effi - ciency and thd+n performance. the ics active emis - sions limiting and class dg multilevel output modulation allow for filterless operation while reducing external com - ponent count, and thereby, cost. because the switching frequency of the ics is well beyond the bandwidth of most speakers, voice coil movement due to the switching frequency is very small. use a speaker with a series inductance > 10h. typical 8 speakers exhibit series inductances in the 20h to 100h range. differential input ampliier the ics feature a differential input configuration, making the device compatible with many codecs and offering improved noise immunity as compared to single-ended input amplifiers. in devices such as mobile phones, noisy digital signals can be picked up by an amplifiers input traces. a differential amplifier amplifies the difference of the two inputs, while signals common to both inputs, such as switching noise, are rejected. while both ics feature differential amplifiers, their voltage gain is set in differing manners. the MAX98307 employs external feedback resistors as shown in figure 4 . voltage gain of the input amplifier is set as: ( ) fb v in r a 20log db 8.5 db r ?? = + ?? ?? where a v is the desired voltage gain in decibels. r in+ should be equal to r in- , and r fb+ should be equal to r fb- . in differential input configurations, the common-mode rejection ratio (cmrr) is primarily limited by the external resistor and capacitor matching. ideally, to achieve the highest possible cmrr, the following external compo - nents should be selected where: fb fb- in in- in in- rr rr and cc + + + = = the gain of the max98308 is selectable by connecting the gain-select bump gain as described in table 1 . figure 4. setting the voltage gain of the MAX98307 class dg output stage fb+ in+ in- fb- r fb- r fb+ r in+ r in- MAX98307 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 15 downloaded from: http:///
component selectionpower-supply input (pvdd) pvdd powers the speaker amplifier and has a range of 2.6v to 5.25v. bypass pvdd with 0.1f and 10f capacitors in parallel to pgnd. apply additional bulk capacitance at the device if long input traces between pvdd and the supply are used. input coupling capacitors the ac-coupling capacitors (c in ) and input resistors (r in ) form highpass filters that remove any dc bias from an input signal. see the MAX98307 typical application circuit and max98308 typical application circuit . c in prevents any dc components from the input signal source appearing at the amplifier outputs. the -3db point of the highpass filter, assuming zero source impedance due to the input signal source, is given by: 3 db in in 1 f 2r c ? = choose c in so that f -3db is well below the lowest frequen - cy of interest. setting f -3db too high affects the amplifiers low-frequency response. use capacitors with adequately low voltage coefficient (x5r or x7r recommended) for best low frequency thd+n performance. charge-pump capacitor selection use capacitors with an equivalent series resistance (esr) less than 50m for optimum performance. low-esr ceramic capacitors minimize the output resistance of the charge pump. for best performance over the extended temperature range, select capacitors with an x7r dielec - tric and a rated voltage of at least 6.3v. charge-pump flying capacitor the value of the charge-pump flying capacitor affects the load regulation and output resistance of the charge pump. a charge-pump flying capacitor value that is too small (less than 1f) degrades the amplifiers ability to provide sufficient current drive. increasing the value of this flying capacitor and decreasing the esr improves load regula - tion and reduces the charge-pump output impedance, which improves the output power and efficiency of the amplifier. a 4.7f or greater value, low-esr capacitor is recommended. charge-pump hold capacitor the charge-pump hold capacitor value and esr directly affect the ripple at the charge-pump rail, pvss. increasing the charge-pump hold capacitor value reduces output ripple. likewise, decreasing the esr of this capacitor reduces both ripple and output resistance. a 10f or greater value, low-esr capacitor is recommended. layout and grounding proper layout and grounding are essential for optimum performance. good grounding improves audio perfor - mance and prevents switching noise from coupling into the audio signal. use wide, low-resistance output traces. as load imped - ance decreases, the current drawn from the device increases. at higher current, the resistance of the output traces decreases the power delivered to the load. for example, if 2w is delivered from the device output to an 8 load through 100m of total speaker trace, 1.97w is delivered to the speaker. if power is delivered through 10m of total speaker trace, 1.998w is delivered to the speaker. wide output, supply, and ground traces also improve the power dissipation of the device. the ics are inherently designed for excellent rf immu - nity. for best performance, add ground fills around all signal traces on top or bottom pcb planes. note: for both ics, the class dg output stage has a fixed gain of 8.5db. any gain or attenuation set by the external input stage resistors adds to or subtracts from this fixed gain. table 1. max98308 gain configuration gain preamplifier gain (db) overall gain (db) unconnected 0 8.5 100k? to v pvdd 3 11.5 short to v pvdd 6 14.5 100k? to pgnd 9 17.5 short to pgnd 12 20.5 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 16 downloaded from: http:///
thermal considerations class dg multilevel amplifiers provide much better effi - ciency and thermal performance than a comparable class ab or class g amplifier. however, the systems thermal performance must be considered with realistic expecta - tions and include consideration of many parameters. this section examines class dg multilevel amplifiers using general examples to illustrate good design practices. MAX98307 (tqfn) applications information the exposed pad is the primary route of keeping heat away from the ic. with a bottom-side exposed pad, the pcb and its copper becomes the primary heatsink for the class dg multilevel 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 amplifier as well as to any adjacent components, provided these con - nections are at the same potential. these copper paths must be as wide as possible. each of these paths con - tributes 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 pcb. make this polygon as large as possible within the sys - tems constraints for signal routing. max98308 (wlp) applications information for the latest application details on wlp construction, dimensions, tape carrier information, pcb techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability test - ing results, refer to application note 1891: wafer-level packaging (wlp) and its applications . note: all devices operate over the -40c to +85c temperature range.+ denotes a lead(pb)-free/rohs-compliant package. /v denotes an automotive qualified part. * ep = exposed pad. ordering information part gain set pin-package MAX98307 ete+ external 16 tqfn-ep* MAX98307ete/v+ external 16 tqfn-ep* max98308 ewc+ internal 12 wlp MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 17 downloaded from: http:///
package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different su ffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 16 tqfn-ep t1633+5 21-0136 90-0032 12 wlp w121a1+1 21-0542 refer to application note 1891 MAX98307/max98308 3.3w mono class dg multilevel audio ampliier www.maximintegrated.com maxim integrated 18 downloaded from: http:///
revision history revision number revision date description pages changed 0 6/11 initial release 1 8/11 updated output power conditions in the electrical characteristics table 4 2 9/11 updated electrical characteristics table and toc 20 2, 4, 8 3 9/11 added ep to the pin description section and removed future product reference for the max98308 12, 17 4 3/12 added r in typical values for all gains and corrected error on tocs 1C6 3, 6 5 3/15 added MAX98307ete/v+ to ordering information 17 6 6/16 updated package code and outline number in package information table 18 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. MAX98307/max98308 3.3w mono class dg multilevel audio ampliier ? 2014 maxim integrated products, inc. 19 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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