View MAX4409EUD_4489392.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

general description the max4409 stereo headphone amplifier combines maxim? directdrive architecture and a common- mode sense input, which allows the amplifier to reject common-mode noise. conventional headphone ampli- fiers require a bulky dc-blocking capacitor between the headphone and the amplifier. directdrive produces a ground-referenced output from a single supply, elimi- nating the need for large dc-blocking capacitors, which saves cost, board space, and component height. the common-mode voltage sensing corrects for any difference between sgnd of the amplifier and the headphone return. this feature minimizes ground-loop noise when the hp socket is used as a line out connec- tion to other grounded equipment, for example, a pc connected to a home hi-fi system. the max4409 draws only 5ma of supply current, deliv- ers up to 80mw per channel into a 16 load, and has a low 0.002% thd+n. a high 86db power-supply rejec- tion ratio allows this device to operate from noisy digital supplies without additional power-supply conditioning. the max4409 includes ?kv esd protection on the headphone outputs. comprehensive click-and-pop cir- cuitry eliminates audible clicks and pops on startup and shutdown. a low-power shutdown mode reduces supply current draw to only 6?. the max4409 operates from a single 1.8v to 3.6v sup- ply, has short-circuit and thermal overload protection, and is specified over the extended -40? to +85? tem- perature range. the max4409 is available in tiny 20-pin thin qfn (4mm x 4mm x 0.8mm) and 14-pin tssop packages. applications features ? no bulky dc-blocking capacitors required ? ground-referenced outputs eliminate dc-bias voltages on headphone ground pin ? common-mode voltage sensing eliminates ground-loop noise ? 96db cmrr ? no degradation of low-frequency response due to output capacitors ? 80mw per channel into 16 ? low 0.002% thd+n ? high 86db psrr ? integrated click-and-pop suppression ? 1.8v to 3.6v single-supply operation ? low quiescent current ? low-power shutdown mode ? short-circuit and thermal-overload protection ? 8kv esd-protected amplifier outputs ? available in space-saving packages 14-pin tssop 20-pin thin qfn (4mm x 4mm x 0.8mm) max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ________________________________________________________________ maxim integrated products 1 left audio input right audio input shdn com max4409 directdrive outputs eliminate dc-blocking capacitors common-mode sense input eliminates ground-loop noise functional diagram ordering information 19-2842; rev 2; 11/07 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com part temp range pin-package max4409etp -40? to +85? 20 thin qfn-ep* MAX4409EUD -40? to +85? 14 tssop notebooks desktop pcs cellular phones pdas mp3 players tablet pcs portable audio equipment pin configurations and typical application circuit appear at end of data sheet. * ep = exposed paddle.
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (pv dd = sv dd = 3v, pgnd = sgnd = 0v, shdn = sv dd , c1 = c2 = 2.2?, r in = r f = r1 = r2 = 10k , r l = , t a = t min to t max , unless otherwise noted. typical values are at t a = +25?.) (note 2) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. pgnd to sgnd .....................................................-0.3v to +0.3v pv dd to sv dd ................................................................. -0.3v to +0.3v pv ss to sv ss .........................................................-0.3v to +0.3v pv dd and sv dd to pgnd or sgnd .........................-0.3v to +4v pv ss and sv ss to pgnd or sgnd ..........................-4v to +0.3v in_ and com to sgnd.................................sv ss to (sv dd - 1v) in_ to com .....................................(com + 2v) to (com - 0.3v) shdn_ to sgnd........................(sgnd - 0.3v) to (sv dd + 0.3v) out_ to sgnd ............................(sv ss - 0.3v) to (sv dd + 0.3v) c1p to pgnd.............................(pgnd - 0.3v) to (pv dd + 0.3v) c1n to pgnd .............................(pv ss - 0.3v) to (pgnd + 0.3v) output short circuit to gnd or v dd ...........................continuous thermal limits (note 1) continuous power dissipation (t a = +70?) 20-pin thin qfn multilayer (derate 25.6mw/? above +70?).............................................................2051mw ja ................................................................................39?/w jc ...............................................................................5.7?/w 14-pin tssop multilayer (derate 10mw/? above +70?)...............................................................797mw ja ..............................................................................100?/w jc ................................................................................30?/w junction temperature ......................................................+150? operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol conditions min typ max units supply voltage range v dd guaranteed by psrr test 1.8 3.6 v quiescent supply current i dd 5 8.4 ma shutdown supply current i shdn shdn = gnd 6 10 a v ih 0.7 x sv dd shdn thresholds v il 0.3 x sv dd v shdn input leakage current -1 +1 ? shdn to full operation t son 175 ? charge pump oscillator frequency f osc 272 320 368 khz amplifiers input offset voltage v os r l = 32 v com +500mv, r source 10 75 96 db 1.8v v dd 3.6v dc (note 3) 75 86 f ripple = 1khz 76 power-supply rejection ratio psrr v dd = 3.0v, 200mv p-p ripple (note 4) f ripple = 20khz 48 db r l = 32 65 output power p out thd+n = 1%, t a = +25? r l = 16 55 80 mw note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a 4-layer board. for detailed information on package thermal considerations see www.maxim-ic.com/thermal-tutorial .
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense _______________________________________________________________________________________ 3 electrical characteristics (continued) (pv dd = sv dd = 3v, pgnd = sgnd = 0v, shdn = sv dd , c1 = c2 = 2.2?, r in = r f = r1 = r2 = 10k , r l = , t a = t min to t max , unless otherwise noted. typical values are at t a = +25?.) (note 2) note 2: all specifications are 100% tested at t a = +25?; temperature limits are guaranteed by design. note 3: inputs are connected to ground and com. note 4: inputs are ac-coupled to ground. com is connected to ground. parameter symbol conditions min typ max units r l = 32 , p out = 50mw 0.002 total harmonic distortion plus noise thd+n f in = 1khz r l = 16 , p out = 60mw 0.005 % signal-to-noise ratio (note 4) snr r l = 32 , p out = 20mw, f in = 1khz 95 db slew rate sr 0.8 v/? maximum capacitive load c l no sustained oscillations 150 pf crosstalk r l = 16 , p out = 1.6mw, f in = 10khz 55 db thermal shutdown threshold 140 ? thermal shutdown hysteresis 15 ? esd protection human body model (outr, outl) ? kv typical operating characteristics ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. ) 10 100 10k 1k 100k total harmonic distortion plus noise vs. frequency max4409 toc01 frequency (hz) thd+n (%) 1 0.1 0.001 0.01 v dd = 3v r l = 16 p out = 10mw p out = 60mw 1 0.001 total harmonic distortion plus noise vs. frequency 0.01 0.1 max4409 toc02 thd+n (%) 10 100 10k 1k 100k frequency (hz) v dd = 3v r l = 32 p out = 50mw p out = 10mw total harmonic distortion plus noise vs. frequency max4409 toc03 thd+n (%) 1 0.1 0.001 0.01 v dd = 1.8v r l = 16 p out = 5mw p out = 15mw 10 100 10k 1k 100k frequency (hz)
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 4 _______________________________________________________________________________________ typical operating characteristics (continued) ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. ) 1 total harmonic distortion plus noise vs. frequency 0.001 0.01 0.1 max4409 toc04 v dd = 1.8v r l = 32 thd+n (%) p out = 15mw p out = 5mw 10 100 10k 1k 100k frequency (hz) 100 10 1 0.1 0.01 0.001 090 120 150 30 60 180 total harmonic distortion plus noise vs. output power max4409 toc05 output power (w) thd+n (%) v dd = 3v f = 20hz r l = 16 outputs out of phase outputs in phase 100 10 1 0.1 0.01 0.001 090 120 150 30 60 180 total harmonic distortion plus noise vs. output power max4409 toc06 output power (w) thd+n (%) v dd = 3v f = 1khz r l = 16 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 090 60 120 150 30 180 total harmonic distortion plus noise vs. output power max4409 toc07 output power (w) thd+n (%) v dd = 3v f = 10khz r l = 16 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0.0001 0 40 60 80 20 120 100 total harmonic distortion plus noise vs. output power max4409 toc08 output power (w) thd+n (%) v dd = 3v f = 20hz r l = 32 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0 40 100 60 80 20 120 total harmonic distortion plus noise vs. output power max4409 toc09 output power (w) thd+n (%) v dd = 3v f = 1khz r l = 32 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0 40 100 80 60 20 120 total harmonic distortion plus noise vs. output power max4409 toc10 output power (w) thd+n (%) v dd = 3v f = 10khz r l = 32 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0204050 30 10 60 total harmonic distortion plus noise vs. output power max4409 toc11 output power (w) thd+n (%) v dd = 1.8v f = 20hz r l = 16 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0204050 30 10 60 total harmonic distortion plus noise vs. output power max4409 toc12 output power (w) v dd = 1.8v f = 1khz r l = 16 thd+n (%) outputs in phase outputs out of phase
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense _______________________________________________________________________________________ 5 100 10 1 0.1 0.01 0.001 0204050 30 10 60 total harmonic distortion plus noise vs. output power max4409 toc13 output power (w) v dd = 1.8v f = 10khz r l = 16 thd+n (%) outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 03040 20 10 total harmonic distortion plus noise vs. output power max4409 toc14 output power (w) thd+n (%) v dd = 1.8v f = 20hz r l = 32 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 02040 30 10 total harmonic distortion plus noise vs. output power max4409 toc15 output power (w) thd+n (%) v dd = 1.8v f = 1khz r l = 32 outputs in phase outputs out of phase 100 10 1 0.1 0.01 0.001 0 20 30 40 10 total harmonic distortion plus noise vs. output power max4409 toc16 output power (w) thd+n (%) v dd = 1.8v f = 10khz r l = 32 outputs in phase outputs out of phase 10 100 10k 1k 100k power-supply rejection ratio vs. frequency max4409 toc17 frequency (hz) psrr (db) 0 -30 -40 -20 -10 -90 -70 -80 -50 -60 v dd = 3v v in = 200mv p-p r l = 16 10 100 10k 1k 100k power-supply rejection ratio vs. frequency max4410 toc18 frequency (hz) psrr (db) 0 -40 -10 -20 -30 -90 -70 -80 -50 -60 v dd = 3v v in = 200mv p-p r l = 16 10 100 10k 1k 100k power-supply rejection ratio vs. frequency max4410 toc19 frequency (hz) psrr (db) 0 -40 -10 -20 -30 -90 -70 -80 -50 -60 v dd = 1.8v v in = 200mv p-p r l = 16 10 100 10k 1k 100k power-supply rejection ratio vs. frequency max4410 toc20 frequency (hz) psrr (db) 0 -40 -10 -20 -30 -90 -70 -80 -60 -50 v dd = 1.8v v in = 200mv p-p r l = 32 crosstalk vs. frequency max4410 toc21 frequency (hz) crosstalk (db) 10k 1k 100 -80 -60 -70 -40 -50 -10 -20 -30 0 -90 10 100k left to right right to left v in = 200mv p-p typical operating characteristics (continued) ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. )
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 6 _______________________________________________________________________________________ typical operating characteristics (continued) ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. ) common-mode rejection ratio vs. frequency max4409 toc22 frequency (hz) cmrr (db) 10k 1k 100 -90 -70 -80 -40 -50 -60 -10 -20 -30 0 -100 10 100k v in = 500mv p-p output power vs. supply voltage max4409 toc23 supply voltage (v) output power (mw) 3.3 3.0 2.7 2.4 2.1 20 40 60 80 100 120 140 160 180 200 0 1.8 3.6 f in = 1khz r l = 16 thd+n = 1% inputs in phase inputs 180 out of phase output power vs. supply voltage max4409 toc24 supply voltage (v) output power (mw) 3.3 3.0 2.7 2.4 2.1 50 100 150 200 250 300 0 1.8 3.6 f in = 1khz r l = 16 thd+n = 10% inputs in phase inputs 180 out of phase output power vs. supply voltage max4409 toc25 supply voltage (v) output power (mw) 3.3 3.0 2.7 2.4 2.1 20 40 60 80 100 120 140 0 1.8 3.6 f in = 1khz r l = 32 thd+n = 1% inputs 180 out of phase inputs in phase output power vs. supply voltage max4409 toc26 supply voltage (v) output power (mw) 3.3 3.0 2.7 2.4 2.1 40 20 60 80 100 120 140 160 180 0 1.8 3.6 f in = 1khz r l = 32 thd+n = 10% inputs in phase inputs 180 out of phase output power vs. load resistance max4409 toc27 load resistance ( ) output power (mw) 10k 1k 100 40 20 60 80 100 120 140 160 0 10 100k v dd = 3v f in = 1khz thd+n = 1% inputs 180 out of phase inputs in phase output power vs. load resistance max4409 toc28 load resistance ( ) output power (mw) 10k 1k 100 50 100 150 200 250 0 10 100k inputs in phase inputs 180 out of phase v dd = 3v f in = 1khz thd+n = 10% output power vs. load resistance max4409 toc29 load resistance ( ) output power (mw) 10k 1k 100 5 10 15 20 25 30 35 40 45 0 10 100k inputs 180 out of phase inputs in phase v dd = 1.8v f in = 1khz thd+n = 1% output power vs. load resistance max4409 toc30 load resistance ( ) output power (mw) 10k 1k 100 10 20 30 40 50 60 70 0 10 100k inputs 180 out of phase inputs in phase v dd = 1.8v f in = 1khz thd+n = 10%
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense _______________________________________________________________________________________ 7 power dissipation vs. output power max4409 toc31 output power (mw) power dissipation (mw) 160 120 40 80 50 100 150 200 250 300 350 400 0 0 200 inputs 180 out of phase f in = 1khz r l = 16 v dd = 3v p out = p outl + p outr inputs in phase power dissipation vs. output power max4409 toc32 output power (mw) power dissipation (mw) 160 120 40 80 20 40 60 80 120 100 140 160 180 0 0200 inputs 180 out of phase f in = 1khz r l = 32 v dd = 3v p out = p outl + p outr inputs in phase power dissipation vs. output power max4409 toc33 output power (mw) power dissipation (mw) 50 40 30 10 20 20 40 60 80 100 120 140 0 060 inputs 180 out of phase f in = 1khz r l = 16 v dd = 1.8v p out = p outl + p outr inputs in phase power dissipation vs. output power max4409 toc34 output power (mw) power dissipation (mw) 50 40 30 10 20 10 20 30 40 50 60 70 0 060 inputs 180 out of phase f in = 1khz r l = 32 v dd = 1.8v p out = p outl + p outr inputs in phase 80 60 40 100 10k 100k 1m 10m 20 0 -20 -40 -60 -80 -100 -180 -120 -140 -160 gain and phase vs. frequency max4409 toc35 frequency (hz) gain/phase (db/degrees) v dd = 3v a v = 1000v/v r l = 16 1k gain phase 10 10 1k 10k 1m 100k 10m 0 -10 -20 -30 -50 -40 gain flatness vs. frequency max4410 toc36 frequency (hz) gain (db) v dd = 3v a v = -1v/v r l = 16 100 charge-pump output resistance vs. supply voltage max4409 toc37 supply voltage (v) output resistance ( ) 3.3 3.0 2.7 2.4 2.1 2 4 6 8 10 0 1.8 3.6 v in_ = gnd i pvss = 10ma no load output power vs. charge-pump capacitance and load resistance max4409 toc38 load resistance ( ) output power (mw) 40 30 20 20 10 30 40 50 60 70 80 90 0 10 50 f in = 1khz thd+n = 1% inputs in phase c1 = c2 = 1 f c1 = c2 = 0.47 f c1 = c2 = 0.68 f c1 = c2 = 2.2 f frequency (hz) 10k 1k 100 100k output spectrum vs. frequency max4409 toc39 output spectrum (db) -100 -80 -60 -40 -20 0 -120 v in = 1v p-p f in = 1khz r l = 32 a v = -1v/v typical operating characteristics (continued) ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. )
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 8 _______________________________________________________________________________________ pin description pin tssop thin qfn name function 118 com common-mode voltage sense input 219 pv dd charge-pump power supply. powers charge-pump inverter, charge-pump logic, and oscillator. 3 1 c1p flying capacitor positive terminal 42 pgnd power ground. connect to sgnd. 5 3 c1n flying capacitor negative terminal 65 pv ss charge-pump output 77 sv ss amplifier negative power supply. connect to pv ss . 89 outl left-channel output 910 sv dd amplifier positive power supply. connect to pv dd . 10 13 inl left-channel audio input 11 11 outr right-channel output 12 14 shdn active-low shutdown. connect to v dd for normal operation. 13 15 inr right-channel audio input 14 17 sgnd signal ground. connect to pgnd. 4, 6, 8, 12, 16, 20 n.c. no connection. not internally connected. ep exposed paddle. leave unconnected. do not connect to v dd or gnd. typical operating characteristics (continued) ( c1 = c2 = 2.2f, r in = r f = r1 = r2 = 10k , thd+n measurement bandwidth = 22hz to 22khz, t a = +25?, unless otherwise noted. ) supply current vs. supply voltage max4409 toc40 supply voltage (v) supply current (ma) 2.7 1.8 0.9 2 4 6 8 10 0 03.6 shutdown supply current vs. supply voltage max4409 toc41 supply voltage (v) supply current ( a) 2.7 1.8 0.9 2 4 6 8 10 0 03.6 shdn = gnd power-up/down waveform max4409 toc42 out_ out_fft v dd 3v 20db/div 10mv/div 0v 200ms/div fft: 25hz/div r l = 32 v in_ = gnd -100db
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense _______________________________________________________________________________________ 9 detailed description the max4409 stereo headphone driver features maxim? directdrive architecture, eliminating the large output- coupling capacitors required by traditional single-supply headphone drivers. the device consists of two 80mw class ab headphone drivers, undervoltage lockout (uvlo)/shutdown control, charge-pump, and compre- hensive click-and-pop suppression circuitry (see typical application circuit ). the charge pump inverts the posi- tive supply (pv dd ), creating a negative supply (pv ss ). the headphone drivers operate from these bipolar sup- plies with their outputs biased about gnd (figure 1). the drivers have almost twice the supply range compared to other 3v single-supply drivers, increasing the available output power. the benefit of this gnd bias is that the dri- ver outputs do not have a dc component typically v dd /2. thus, the large dc-blocking capacitors are unnecessary, improving frequency response while con- serving board space and system cost. the max4409 also features a common-mode voltage sense input that corrects for mismatch between the sgnd of the device and the potential at the headphone jack return. a low-power shutdown mode reduces sup- ply current to 6?. the device features an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop suppression that elim- inates audible transients on startup and shutdown. additionally, the max4409 features thermal overload and short-circuit protection and can withstand 8kv esd strikes on the output pins. common-mode sense when the headphone jack is used as a line out to inter- face between other equipment (notebooks, desktops, and stereo receivers), potential differences between the equipment grounds can create ground loops and excessive ground current flow. the max4409 com input senses and corrects for the difference between the headphone return and device ground. connect com through a resistive voltage-divider between the headphone jack return and sgnd of the device (see typical application circuit). for optimum common- mode rejection, use the same value resistors for r2 and r in , and r1 and r f . improve dc cmrr by adding a capacitor in between with sgnd and r2 (see typical application circuit). if ground sensing is not required, connect com directly to sgnd through a 5k resistor. directdrive traditional single-supply headphone drivers have their outputs biased about a nominal dc voltage (typically half the supply) for maximum dynamic range. large coupling capacitors are needed to block this dc bias from the headphone. without these capacitors, a signif- icant amount of dc current flows to the headphone, resulting in unnecessary power dissipation and possi- ble damage to both headphone and headphone driver. maxim? directdrive architecture uses a charge pump to create an internal negative supply voltage. this allows the outputs of the max4409 to be biased about gnd, almost doubling dynamic range while operating from a single supply. with no dc component, there is no need for the large dc-blocking capaci- tors. instead of two large (220?, typ) tantalum capacitors, the max4409 charge pump requires two small ceramic capacitors, thereby conserving board space, reducing cost, and improving the frequency response of the headphone driver. see the output power vs. charge-pump capacitance and load resistance graph in the typical operating char- acteristics for details of the possible capacitor sizes. there is a low dc voltage on the driver outputs due to amplifier offset. however, the offset of the max4409 is +v dd -v dd gnd v out conventional driver-biasing scheme directdrive biasing scheme v dd /2 v dd gnd v out figure 1. traditional driver output waveform vs. max4409 output waveform
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 10 ______________________________________________________________________________________ typically 0.5mv, which, when combined with a 32 load, results in less than 16? of dc current flow to the headphones. previous attempts to eliminate the output-coupling capac- itors involved biasing the headphone return (sleeve) to the dc-bias voltage of the headphone amplifiers. this method raises some issues: when combining a microphone and headphone on a single connector, the microphone bias scheme typically requires a 0v reference. the sleeve is typically grounded to the chassis. using this biasing approach, the sleeve must be isolated from system ground, complicating product design. during an esd strike, the driver? esd structures are the only path to system ground. thus, the driver must be able to withstand the full esd strike. when using the headphone jack as a line out to other equipment, the bias voltage on the sleeve may con- flict with the ground potential from other equipment, resulting in possible damage to the drivers. low-frequency response in addition to the cost and size disadvantages of the dc- blocking capacitors required by conventional head- phone amplifiers, these capacitors limit the amplifier? low-frequency response and can distort the audio signal: the impedance of the headphone load and the dc- blocking capacitor form a highpass filter with the -3db point set by: where r l is the headphone impedance and c out is the dc-blocking capacitor value. the highpass filter is required by conventional single-ended, single power-supply headphone drivers to block the midrail dc bias component of the audio signal from the headphones. the drawback to the filter is that it can attenuate low-frequency signals. larger values of c out reduce this effect but result in physically larg- er, more expensive capacitors. figure 2 shows the relationship between the size of c out and the result- ing low-frequency attenuation. note that the -3db point for a 16 headphone with a 100? blocking capacitor is 100hz, well within the normal audio band, resulting in low-frequency attenuation of the reproduced signal. the voltage coefficient of the dc-blocking capacitor contributes distortion to the reproduced audio signal as the capacitance value varies as a function of the voltage change across the capacitor. at low fre- quencies, the reactance of the capacitor dominates at frequencies below the -3db point and the voltage coefficient appears as frequency-dependent distor- tion. figure 3 shows the thd+n introduced by two different capacitor dielectric types. note that below 100hz, thd+n increases rapidly. the combination of low-frequency attenuation and fre- quency-dependent distortion compromises audio reproduction in portable audio equipment that empha- sizes low-frequency effects such as multimedia lap- f rc db l out - 2 3 1 = lf roll off (16 load) max4409 fig02 frequency (hz) attenuation (db) 100 -30 -25 -20 -10 -3db corner for 100 f is 100hz -15 -5 -3 0 -35 10 1k 33 f 330 f 220 f 100 f figure 2. low-frequency attenuation for common dc-blocking capacitor values additional thd+n due to dc-blocking capacitors max4409 fig03 frequency (hz) thd+n (%) 10k 1k 100 0.001 0.01 0.1 1 10 0.0001 10 100k tantalum alum/elec figure 3. distortion contributed by dc-blocking capacitors
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ______________________________________________________________________________________ 11 tops, as well as mp3, cd, and dvd players. by elimi- nating the dc-blocking capacitors through directdrive technology, these capacitor-related deficiencies are eliminated. charge pump the max4409 features a low-noise charge pump. the 320khz switching frequency is well beyond the audio range, and thus does not interfere with the audio sig- nals. the switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. by limiting the switching speed of the switches, the di/dt noise caused by the parasitic bond wire and trace inductance is minimized. although not typically required, additional high-frequency noise atten- uation can be achieved by increasing the size of c2 (see typical application circuit ). shutdown the max4409 features an active-low shdn control. driving shdn low disables the charge pump and amplifiers, sets the amplifier output impedance to approximately 1k , and reduces supply current draw to less than 6?. click-and-pop suppression in traditional single-supply audio drivers, the output- coupling capacitor is a major contributor of audible clicks and pops. upon startup, the driver charges the coupling capacitor to its bias voltage, typically half the supply. likewise, on shutdown the capacitor is dis- charged to gnd. this results in a dc shift across the capacitor, which in turn, appears as an audible transient at the speaker. since the max4409 does not require output-coupling capacitors, this does not arise. additionally, the max4409 features extensive click-and- pop suppression that eliminates any audible transient sources internal to the device. the power-up/down waveform in the typical operating characteristics shows that there are minimal spectral components in the audible range at the output upon startup or shutdown. in most applications, the output of the preamplifier dri- ving the max4409 has a dc bias of typically half the supply. at startup, the input-coupling capacitor is charged to the preamplifier? dc-bias voltage through the r f of the max4409, resulting in a dc shift across the capacitor and an audible click/pop. delaying the rise of the shdn_ signals 4 to 5 time constants (40ms to 50ms) based on r in and c in relative to the start of the preamplifier eliminates this click/pop caused by the input filter. applications information power dissipation under normal operating conditions, linear power ampli- fiers can dissipate a significant amount of power. the maximum power dissipation for each package is given in the absolute maximum ratings section under continuous power dissipation or can be calculated by the following equation: where t j(max) is +150?, t a is the ambient temperature, and ja is the reciprocal of the derating factor in ?/w as specified in the absolute maximum ratings section. for example, ja of the tssop package is +109.9?/w. the max4409 has two sources of power dissipation, the charge pump and two drivers. if the power dissipa- tion for a given application exceeds the maximum allowed for a given package, either reduce v dd , increase load impedance, decrease the ambient tem- perature, or add heat sinking to the device. large out- put, supply, and ground traces improve the maximum power dissipation in the package. thermal overload protection limits total power dissipa- tion in the max4409. when the junction temperature exceeds +140?, the thermal-protection circuitry dis- ables the amplifier output stage. the amplifiers are enabled once the junction temperature cools by 15?. this results in a pulsing output under continuous ther- mal-overload conditions. output power the device has been specified for the worst-case sce- nario?hen both inputs are in phase. under this con- dition, the drivers simultaneously draw current from the charge pump, leading to a slight loss in headroom of v ss . in typical stereo audio applications, the left and right signals have differences in both magnitude and phase, subsequently leading to an increase in the max- imum attainable output power. figure 4 shows the two extreme cases for in and out of phase. in reality, the available power lies between these extremes. powering other circuits from a negative supply an additional benefit of the max4409 is the internally generated, negative supply voltage (pv ss ). this volt- age is used by the max4409 to provide the ground-ref- erenced output level. it can, however, also be used to power other devices within a design. current draw from this negative supply (pv ss ) should be limited to 5ma; exceeding this affects the operation of the headphone p tt disspkg max j max a ja () () = ?
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 12 ______________________________________________________________________________________ driver. the negative supply voltage appears on the pv ss pin. a typical application is a negative supply to adjust the contrast of lcd modules. when considering the use of pv ss in this manner, note that the charge-pump voltage at pv ss is roughly pro- portional to -v dd and is not a regulated voltage. the charge-pump output impedance plot appears in the typical operating characteristics . component selection gain-setting resistors external feedback components set the gain of the max4409. resistors r f and r in (see typical application circuit ) set the gain of each amplifier as follows: choose feedback resistor values of 10k . values other than 10k increase v os due to the input bias current, which in turn increases the amount of dc current flow to the load. resistors r in , r2, r f , and r1 must be of equal value for best results. use high-tolerance resis- tors for best matching and cmrr. for example, the worst-case cmrr attributed to a 1% resistor mismatch is -34db. this is the worst case, and typical resistors do not affect cmrr as drastically. the effect of resistor mismatch is shown in figure 5. if all resistors match exactly, then any voltage applied to node a should be duplicated on out so no net differential voltage appears between node a (normally the hp jack socket gnd) and out. for resistors with a tolerance of n%, the worst mismatch is found when r in and r1 are at +n%, and r f and r2 are at -n%. if all four resistors are nominally the same value, then 2n% of the voltage at a appears between a and out. packaged resistor arrays can provide well-matched components for this type of application. although their absolute tolerance is not well controlled, the internal matching of resistors can be very good. at higher fre- quencies, the rejection is usually limited by pc board layout; care should be taken to make sure any stray capacitance due to pc board traces on node n1 match- es those on node n2. ultimately, cmrr performance is limited by the amplifier itself (see electrical characteristics) . compensation capacitor the stability of the max4409 is affected by the value of the feedback resistor (r f ). the combination of r f and the input and parasitic trace capacitance introduces an additional pole. adding a capacitor in parallel with r f compensates for this pole. under typical conditions with proper layout, the device is stable without the additional capacitor. input filtering the input capacitor (c in ), in conjunction with r in, forms a highpass filter that removes the dc bias from an incom- ing signal (see typical application circuit ). the ac-cou- pling capacitor allows the amplifier to bias the signal to an optimum dc level. assuming zero-source impedance, the -3db point of the highpass filter is given by: f rc db in in - 2 3 1 = a v = ? ? ? ? ? ? ? r r f in max4409 r1 n2 n1 r2 r in r f a out figure 5. common-mode sense equivalent circuit 100 10 1 0.1 0.01 0.001 0 100 150 50 200 total harmonic distortion plus noise vs. output power max4409 fig04 output power (mw) v dd = 3v a v = -1v/v r l = 16 f in = 10khz thd+n (%) outputs in phase one channel outputs 180 out of phase figure 4. output power vs. thd+n with inputs in/out of phase
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ______________________________________________________________________________________ 13 choose r in according to the gain-setting resistors sec- tion. choose the c in such that f -3db is well below the lowest frequency of interest. setting f -3db too high affects the low-frequency response of the amplifier. use capacitors whose dielectrics have low-voltage coeffi- cients, such as tantalum or aluminum electrolytic. capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low fre- quencies. charge-pump capacitor selection use capacitors with an esr less than 100m 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. table 1 lists suggested manufacturers. 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? ability to provide sufficient current drive, which leads to a loss of output voltage. increasing the value of c1 improves load regulation and reduces the charge-pump output resistance to an extent. see the output power vs. charge-pump capacitance and load resistance graph in the typical operating characteristics . above 2.2?, the on-resistance of the switches and the esr of c1 and c2 dominate. output capacitor (c2) the output capacitor value and esr directly affect the ripple at pv ss . increasing the value of c2 reduces out- put ripple. likewise, decreasing the esr of c2 reduces both ripple and output resistance. lower capacitance values can be used in systems with low maximum out- put power levels. see the output power vs. charge- pump capacitance and load resistance graph in the typical operating characteristics. power-supply bypass capacitor the power-supply bypass capacitor (c3) lowers the out- put impedance of the power supply, and reduces the impact of the max4409? charge-pump switching tran- sients. bypass pv dd with c3, the same value as c1, and place it physically close to the pv dd and pgnd pins. common-mode noise rejection figure 6 shows a theoretical connection between two devices, for example, a notebook computer (transmit- ter, on the left) and an amplifier (receiver, on the right). the application includes the headphone socket used as a line output to a home hi-fi system, for example. in the upper diagram, any difference between the two gnd references (represented by v noise ) causes cur- rent to flow through the screen of cable between the two devices. this can cause noise pickup at the receiv- er due to the potential divider action of the audio screen cable impedance and the gnd wiring of the amplifier. introducing impedance between the jack socket and gnd of the notebook helps (as shown in the lower dia- gram). this has the following effect: current flow (from gnd potential differences) in the cable screen is reduced, which is a safety issue. it allows the max4409 differential sensing to reduce the gnd noise seen by the receiver (amplifier). the other side effect is the differential hp jack sensing corrects the headphone crosstalk (from introducing the resistance on the jack gnd return). only one channel is depicted in figure 6. figure 6 has some example numbers for resistance, but the audio designer has control over only one series resistance applied to the headphone jack return. note that this resistance can be bypassed for esd purposes at frequencies much higher than audio if required. the upper limit for this added resistance is the amount of output swing the headphone amplifier tolerates when driving low-impedance loads. any headphone return current appears as a voltage across this resistor. layout and grounding proper layout and grounding are essential for optimum performance. connect pgnd and sgnd together at a single point on the pc board. connect all components associated with the charge pump (c2 and c3) to the pgnd plane. connect pv dd and sv dd together at the device. connect pv ss and sv ss together at the device. bypassing of both supplies is accomplished by charge-pump capacitors c2 and c3 (see typical table 1. suggested capacitor manufacturers supplier phone fax website taiyo yuden 800-348-2496 847-925-0899 www.t-yuden.com tdk 847-803-6100 847-390-4405 www.component.tdk.com note: please indicate you are using the max4409 when contacting these component suppliers.
max4409 application circuit ). place capacitors c2 and c3 as close to the device as possible. route pgnd and all traces that carry switching transients away from sgnd and the traces and components in the audio signal path. ensure that the com traces have the same trace length and width as the amplifier input and feedback traces. route com traces away from noisy signal paths. the thin qfn package features an exposed paddle that improves thermal efficiency of the package. however, the max4409 does not require additional heatsinking. ensure that the exposed paddle is isolated from gnd or v dd . do not connect the exposed paddle to gnd or v dd . 80mw, directdrive, stereo headphone amplifier with common-mode sense 14 ______________________________________________________________________________________ v noise v noise 0.1 0.1 0.1 0.1 v ref_in = (v noise x 0.99) v in = v audio + (v noise x 0.98) resistor is inserted between the jack sleeve and gnd = 9.8 v audio v audio gnd noise component in output = v noise /100 example connection: improvement from adding max4409 with series resistance 9.8 resistor adds to hp crosstalk, but differential sensing at the jack sleeve corrects for this (one channel only shown). current flow (in signal cable screen) due to v noise is greatly reduced. noise component in the receiver output is reduced by 34db over the previous example with the values shown. 9.8 0.10 resistance from cable screen 0.10 resistance due to gnd cabling at receiver v noise represents the potential difference between the two gnds v ref_in = v noise /2 v in = v audio gnd noise component in output = v noise /2 max4409 figure 6. common-mode noise rejection
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ______________________________________________________________________________________ 15 typical application circuit charge pump click-and-pop suppression c1n c1p pv ss sv ss pgnd sgnd pv dd sv dd shdn sv ss sv dd inl inr outr left channel audio in right channel audio in headphone jack 12 2 3 4 5 6 7 8 9 10 11 com 1 14 max4409 c1 1 f c2 1 f 1.8v to 3.6v c3 1 f c in 1 f r in 10k r f 10k sv ss sv dd outl c in 1 f r in 10k r f 10k 13 r 1 10k r 2 10k uvlo/ shutdown control *pin numbers are for the tssop package.
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 16 ______________________________________________________________________________________ system diagram max9710 max961 outr+ outr- outl- outl+ inr inl bias pv dd v dd shdn 15k 15k 100k 100k v cc 15k 15k v dd 0.1 f 0.1 f 0.1 f 1 f max4060 max4409 q q in+ 0.1 f outl outr c1p cin com shdn 1 f 1 f 1 f inl inr pv ss sv ss aux_in bias in+ in- 2.2k 0.1 f 0.1 f 0.1 f codec out 10k 10k 10k 10k 10k 1 f 10k 1 f v cc 1 f pv dd sv dd v cc 10k 10k v cc in-
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ______________________________________________________________________________________ 17 20 19 18 17 12 13 14 15 n.c. inl shdn inr 4 3 2 1 n.c. cin pgnd c1p 11 outr 5 p v ss max4409 n.c. pv dd com sgnd n.c. sv ss n.c. outl 16 6 7 8 9 10 n.c. sv dd thin qfn top view 14 13 12 11 10 9 8 1 2 3 4 5 6 7 sgnd inr shdn outr pgnd c1p pv dd com max4409 inl sv dd outl sv ss pv ss c1n tssop pin configurations chip information transistor count: 4295 process: bicmos
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense 18 ______________________________________________________________________________________ 24l qfn thin.eps package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense ______________________________________________________________________________________ 19 tssop4.40mm.eps package outline, tssop 4.40mm body 21-0066 1 1 i package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .
max4409 80mw, directdrive, stereo headphone amplifier with common-mode sense maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 20 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2007 maxim integrated products is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 4/03 initial release 1 6/04 replaced 5mm x 5mm tqfn package information with 4mm x 4mm tqfn package information 1, 18 2 11/07 replaced continuous power dissipation in absolute maximum ratings section, changed ec table notes, updated pin description and package outlines 1, 2, 3, 8, 9, 18, 19

▲Up To Search▲

Price & Availability of MAX4409EUD

	To Download MAX4409EUD Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .