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general description the max9728a/max9728b stereo headphone ampli- fiers are designed for display and notebook applica- tions or portable equipment where board space is at a premium. these devices use a unique directdrive architecture to produce a ground-referenced output from a single supply, eliminating the need for large dc- blocking capacitors, saving cost, board space, and component height. the max9728a offers an externally adjustable gain, while the max9728b has an internally preset gain of -1.5v/v. the max9728a/max9728b deliver up to 60mw per channel into a 32 load and have low 0.02% thd+n. an 80db at 1khz power-sup- ply rejection ratio (psrr) allows these devices to oper- ate from noisy digital supplies without an additional linear regulator. comprehensive click-and-pop circuitry suppresses audible clicks and pops on startup and shutdown. the max9728a/max9728b operate from a single 4.5v to 5.5v supply, consume only 3.5ma of supply current, feature short-circuit and thermal-overload protection, and are specified over the extended -40? to +85? temperature range. the devices are available in tiny 12- pin thin qfn (3mm x 3mm x 0.8mm) and 14-pin tssop packages (5mm x 4.4mm x 1.1mm). features ? no bulky dc-blocking capacitors required ? low-power shutdown mode, < 0.1 a ? adjustable gain (max9728a) or fixed -1.5v/v gain (max9728b) ? low 0.02% thd+n ? high psrr (80db at 1khz) eliminates ldo ? integrated click-and-pop suppression ? 4.5v to 5.5v single-supply operation ? low quiescent current (3.5ma) ? available in space-saving packages 12-pin thin qfn (3mm x 3mm x 0.8mm) 14-pin tssop (5mm x 4.4mm x 1.1mm) max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown ________________________________________________________________ maxim integrated products 1 ordering information 19-3963; rev 1; 7/09 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. evaluation kit available part gain (v/v) pin-package top mark MAX9728AETC+ adj. 12 tqfn-ep* abc max9728aeud+ adj. 14 tssop max9728betc+ -1.5 12 tqfn-ep* abd max9728beud+ -1.5 14 tssop note: all devices specified over the -40? to +85? operating range. + denotes lead(pb)-free/rohs-compliant package. * ep = exposed pad. notebook pcs dvd players lcd/pdp displays crt tvs multimedia monitors left audio input right audio input shdn max9728a left audio input right audio input max9728b shdn directdrive outputs eliminate dc-blocking capacitors directdrive outputs eliminate dc-blocking capacitors fixed gain eliminates external resistor network block diagrams pin configurations appear at end of data sheet. applications directdrive is a registered trademark of maxim integrated product, inc.
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 2 _______________________________________________________________________________________ absolute maximum ratings 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. v dd to pgnd............................................................-0.3v to +6v pv ss to sv ss .........................................................-0.3v to +0.3v pgnd to sgnd .....................................................-0.3v to +0.3v c1p to pgnd..............................................-0.3v to (v dd + 0.3v) c1n to pgnd............................................(pv ss - 0.3v) to +0.3v pv ss and sv ss to pgnd..........................................-6v to +0.3v in_ to sgnd (max9728a)..........................-0.3v to (v dd + 0.3v) in_ to sgnd (max9728b) .............(sv ss - 0.3v) to (v dd + 0.3v) out_ to sv ss (note 1) ....-0.3v to min (v dd - sv ss + 0.3v, +9v) out_ to v dd (note 2) ......+0.3v to max (sv ss - v dd - 0.3v, -9v) shdn to _gnd.........................................................-0.3v to +6v out_ short circuit to sgnd ......................................continuous short circuit between outl and outr ....................continuous continuous input current into pv ss ..................................260ma continuous input current (any other pin) .........................?0ma continuous power dissipation (t a = +70?) 12-pin tqfn (derate 14.7mw/? above +70?) .........1177mw 14-pin tssop (derate 9.1mw/? above +70?) ...........727mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? junction temperature ......................................................+150? lead temperature (soldering, 10s) .................................+300? electrical characteristics (v dd = 5v, pgnd = sgnd, shdn = 5v, c1 = c2 = 1?, r l = , resistive load reference to ground; for max9728a gain = -1.5v/v (r in = 20k , r f = 30k ); for max9728b gain = -1.5v/v (internally set), t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units general supply voltage range v dd 4.5 5.5 v quiescent current i cc 3.5 5.5 ma shutdown current i shdn shdn = sgnd = pgnd < 0.1 1 a shutdown to full operation t son 180 ? input impedance r in max9728b, measured at in_ 15 19 25 k output offset voltage v os ?.5 ?0 mv v dd = 4.5v to 5.5v 86 f = 1khz, 100mv p-p 80 power-supply rejection ratio psrr f = 20khz, 100mv p-p 65 db r l = 32 , thd+n = 1% 30 63 output power p out r l = 16 , thd+n = 1% 42 mw voltage gain a v max9728b (note 4) -1.52 -1.5 -1.48 v/v channel-to-channel gain tracking max9728b ?.15 % r l = 1k , v out = 2v rms , f in = 1khz 0.003 r l = 32 , p out = 50mw, f in = 1khz 0.02 total harmonic distortion plus noise thd+n r l = 16 , p out = 35mw, f in = 1khz 0.04 % note 1: outr and outl should be limited to no more than 9v above sv ss , or above v dd + 0.3v, whichever limits first. note 2: outr and outl should be limited to no more than 9v below v dd , or below sv ss - 0.3v, whichever limits first.
max9728a/max9728b 60mw, directdrive, stereo headphone amplifier with shutdown _______________________________________________________________________________________ 3 electrical characteristics (continued) (v dd = 5v, pgnd = sgnd, shdn = 5v, c1 = c2 = 1?, r l = , resistive load reference to ground; for max9728a gain = -1.5v/v (r in = 20k , r f = 30k ); for max9728b gain = -1.5v/v (internally set), t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units bw = 22hz to 22khz 102 r l = 1k , v out = 2v rms a-weighted 105 bw = 22hz to 22khz 98 signal-to-noise ratio snr r l = 32 , p out = 50mw a-weighted 101 db slew rate sr 0.5 v/? capacitive drive c l no sustained oscillations 100 pf crosstalk l to r, r to l, f = 10khz, r l = 16 , p out = 15mw -70 db charge-pump oscillator frequency f osc 190 270 400 khz into shutdown -67 click-and-pop level k cp r l = 32 , peak voltage, a-weighted, 32 samples per second (note 5) out of shutdown -64 db digital inputs ( shdn ) input voltage high v inh 2v input voltage low v inl 0.8 v input leakage current ? ? note 3: all specifications are 100% tested at t a = +25?; temperature limits are guaranteed by design. note 4: gain for the max9728a is adjustable. note 5: test performed with a 32 resistive load connected to sgnd. mode transitions are controlled by shdn . k cp level is calcu- lated as 20log[(peak voltage during mode transition, no input signal)/(peak voltage under normal operation at rated power level)]. units are expressed in db.
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 4 _______________________________________________________________________________________ 100 020 60 40 80 100 10 1 0.1 0.01 0.001 total harmonic distortion plus noise vs. output power max9728a/28b toc01 output power (mw) thd+n (%) v dd = 5v r l = 16 f in = 1khz f in = 20hz f in = 10khz 100 020 60 40 80 120 10 1 0.1 0.01 0.001 total harmonic distortion plus noise vs. output power max9728a/28b toc02 output power (mw) thd+n (%) 100 v dd = 5v r l = 32 f in = 1khz f in = 20hz f in = 10khz 10 1k 100 10k 100k total harmonic distortion plus noise vs. frequency max9728a/28b toc03 frequency (hz) thd+n (%) 1 0.1 0.001 0.01 v dd = 5v r l = 16 p out = 20mw p out = 37mw 10 1k 100 10k 100k total harmonic distortion plus noise vs. frequency max9728a/28b toc04 frequency (hz) thd+n (%) 1 0.1 0.001 0.01 v dd = 5v r l = 32 p out = 50mw p out = 30mw 0 20 10 40 30 60 50 70 4.5 5.0 5.5 output power vs. supply voltage max9728a/28b toc05 supply voltage (v) output power (mw) f in = 1khz r l = 16 thd+n = 1% thd+n = 10% 0 40 20 80 60 100 120 4.5 5.0 5.5 output power vs. supply voltage max9728a/28b toc06 supply voltage (v) output power (mw) f in = 1khz r l = 32 thd+n = 1% thd+n = 10% typical operating characteristics (v dd = 5v, pgnd = sgnd = 0v, shdn = v dd , c1 = c2 = 1?, r l = , gain = -1.5v/v (r in = 20k , r f = 30k for the max9728a), thd+n measurement bandwidth = 22hz to 22khz, both outputs driven in phase, t a = +25?, unless otherwise noted.)
max9728a/max9728b 0 -120 10 100 10k 100k power-supply rejection ratio vs. frequency -100 -80 -40 -60 -20 max9728a/28b toc08 frequency (hz) psrr (db) 1k r l = 32 v dd = 5v 0 -120 10 100 10k 100k crosstalk vs. frequency -100 -80 -40 -60 -20 max9728a/28b toc09 frequency (hz) crosstalk (db) 1k right to left left to right p out = 15mw r l = 16 60mw, directdrive, stereo headphone amplifiers with shutdown _______________________________________________________________________________________ 5 20 40 30 60 50 70 80 0 200 300 100 50 150 250 output power vs. load resistance and charge-pump capacitor size max9728a/28b toc10 load resistance ( ) output power (mw) c1 = c2 = 2.2 f c1 = c2 = 1 f c1 = c2 = 0.47 f v dd = 5v f in = 1khz thd+n = 1% 3.20 3.25 3.40 3.30 3.45 3.35 3.50 4.5 5.0 5.5 supply current vs. supply voltage max9728a/28b toc11 supply voltage (v) supply current (ma) no load inputs ground 0 3 1 7 5 9 2 6 4 8 10 4.5 5.0 5.5 shutdown current vs. supply voltage max9728a/28b toc12 supply voltage (v) shutdown current (na) no load inputs ground 100 0 10 100 1000 output power vs. load resistance 10 max9728a/28b toc07 load resistance ( ) output power (mw) 30 20 50 70 90 40 60 80 v dd = 5v f in = 1khz thd+n = 10% thd+n = 1% typical operating characteristics (continued) (v dd = 5v, pgnd = sgnd = 0v, shdn = v dd , c1 = c2 = 1?, r l = , gain = -1.5v/v (r in = 20k , r f = 30k for the max9728a), thd+n measurement bandwidth = 22hz to 22khz, both outputs driven in phase, t a = +25?, unless otherwise noted.)
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v dd = 5v, pgnd = sgnd = 0v, shdn = v dd , c1 = c2 = 1?, r l = , gain = -1.5v/v (r in = 20k , r f = 30k for the max9728a), thd+n measurement bandwidth = 22hz to 22khz, both outputs driven in phase, t a = +25?, unless otherwise noted.) pin description pin tqfn tssop name function 1 3 c1p flying capacitor positive terminal. connect a 1? ceramic capacitor from c1p to c1n. 2 4 pgnd power ground. connect to sgnd. 3 5 c1n flying capacitor negative terminal. connect a 1? ceramic capacitor from c1p to c1n. 47pv ss charge-pump output. connect to sv ss and bypass with a 1? ceramic capacitor to pgnd. 58 shdn active-low shutdown input 6 9 inl left-channel input 7 10 sgnd signal ground. connect to pgnd. 8 11 inr right-channel input 912sv ss amplifier negative supply. connect to pv ss . 10 14 outr right-channel output 11 1 outl left-channel output 12 2 v dd positive power-supply input. bypass with a 1? capacitor to pgnd. 6,13 n.c. no connection. not internally connected. ep ep exposed paddle. leave this connection floating or connect it to sv ss . exiting shutdown max9728a/28b toc13 v shdn 5v/div v out_ 500mv/div v in_ 1v/div 40 s/div entering shutdown max9728a/28b toc14 v shdn 5v/div v out_ 500mv/div v in_ 1v/div 20 s/div
max9728a/max9728b detailed description the max9728a/max9728b stereo headphone ampli- fiers feature maxim? directdrive architecture, eliminat- ing the large output-coupling capacitors required by conventional single-supply headphone amplifiers. these devices consist of two 60mw class ab head- phone amplifiers, undervoltage lockout (uvlo)/shut- down control, charge pump, and comprehensive click-and-pop suppression circuitry (see the functional diagram/typical operating circuits ). the charge pump inverts the positive supply (v dd ), creating a negative supply (pv ss ). the headphone amplifiers operate from these bipolar supplies with their outputs biased about sgnd (figure 1). the benefit of this sgnd bias is that the amplifier outputs do not have a dc component. the large dc-blocking capacitors required with convention- al headphone amplifiers are unnecessary, conserving board space, reducing system cost, and improving fre- quency response. the max9728a/max9728b feature an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop sup- pression that eliminates audible transients on startup and shutdown. the max9728a/max9728b also feature thermal-overload and short-circuit protection. directdrive conventional single-supply headphone amplifiers have their outputs biased about a nominal dc voltage (typical- ly half the supply) for maximum dynamic range. large- coupling capacitors are needed to block this dc bias from the headphone. without these capacitors, a signifi- cant amount of dc current flows to the headphone, resulting in unnecessary power dissipation and possible damage to both headphone and headphone amplifier. maxim? directdrive architecture uses a charge pump to create an internal negative supply voltage, allowing the max9728a/max9728b outputs to be biased about sgnd. with no dc component, there is no need for the large dc-blocking capacitors. the max9728a/ max9728b charge pumps require two small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the head- phone amplifier. see the output power vs. load resistance and charge-pump capacitor size graph in the typical operating characteristics for details of the possible capacitor sizes. there is a low dc voltage on the amplifier outputs due to amplifier offset. however, the offsets of the max9728a/max9728b are typically 1.5mv, which, when combined with a 32 load, results in less than 47? of dc current flow to the head- phones. charge pump the max9728a/max9728b feature a low-noise charge pump. the 270khz switching frequency is well beyond the audio range and does not interfere with audio sig- nals. the switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. the di/dt noise caused by the para- sitic bond wire and trace inductance is minimized by limiting the switching speed of the charge pump. although not typically required, additional high-fre- quency noise attenuation can be achieved by increas- ing the value of c2 (see the functional diagram/typical operating circuits ). click-and-pop suppression in conventional single-supply audio amplifiers, the out- put-coupling capacitor contributes significantly to audi- ble clicks and pops. upon startup, the amplifier charges the coupling capacitor to its bias voltage, typically half the supply. likewise, on shutdown, the capacitor is dis- charged. this results in a dc shift across the capacitor, which appears as an audible transient at the speaker. 60mw, directdrive, stereo headphone amplifier with shutdown _______________________________________________________________________________________ 7 v dd -v dd sgnd v out conventional driver-biasing scheme directdrive biasing scheme v dd /2 v dd v dd sgnd v out 2v dd figure 1. conventional driver output waveform vs. max9728a/max9728b output waveform
max9728a/max9728b since the max9728a/max9728b do not require output- coupling capacitors, this problem does not arise. additionally, the max9728a/max9728b feature exten- sive click-and-pop suppression that eliminates any audible transient sources internal to the device. typically, the output of the device driving the max9728a/max9728b has a dc bias of half the supply voltage. at startup, the input-coupling capacitor is charged to the preamplifier? dc-bias voltage through the input and feedback resistors of the max9728a/ max9728b, resulting in a dc shift across the capacitor and an audible click/pop. delay the rise of shdn 4 to 5 time constants based on r in and c in , relative to the startup of the preamplifier, to eliminate clicks-and-pops caused by the input filter. shutdown the max9728a/max9728b feature a < 0.1?, low- power shutdown mode that reduces quiescent current consumption and extends battery life for portable appli- cations. drive shdn low to disable the amplifiers and the charge pump. in shutdown mode, the amplifier out- put impedance is set to 14k ||r f (r f is 30k for the max9728b). the amplifiers and charge pump are enabled once shdn is driven high. 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 tempera- ture, and ja is the reciprocal of the derating factor in ?/w as specified in the absolute maximum ratings section. for example, ja of the thin qfn package is +68?/w, and +110?/w for the tssop package. the max9728a/max9728b have two power dissipation sources: a charge pump and the two output amplifiers. if power dissipation for a given application exceeds the maximum allowed for a particular package, reduce v dd , increase load impedance, decrease the ambient temperature, or add heatsinking to the device. large output, supply, and ground traces decrease ja , allow- ing more heat to be transferred from the package to the surrounding air. thermal-overload protection limits total power dissipa- tion in the max9728a/max9728b. when the junction temperature exceeds +150?, the thermal-protection circuitry disables the amplifier output stage. the ampli- fiers are enabled once the junction temperature cools by approximately 12?. this results in a pulsing output under continuous thermal-overload conditions. output dynamic range dynamic range is the difference between the noise floor of the system and the output level at 1% thd+n. determine the system? dynamic range before setting the maximum output gain. output clipping occurs if the output signal is greater than the dynamic range of the system. the directdrive architecture of the max9728a/ max9728b has increased the dynamic range compared to other single-supply amplifiers. maximum output swing internal device structures limit the maximum voltage swing of the max9728a/max9728b. the output must not be driven such that the peak output voltage exceeds the opposite supply voltage by 9v. for example, if v dd = 5v, the charge pump sets pv ss = -5v. therefore, the peak output swing must be less than ?v to prevent exceeding the absolute maximum ratings. component selection input-coupling capacitor the input capacitor (c in ), in conjunction with the input resistor (r in ), forms a highpass filter that removes the dc bias from an incoming signal (see the functional diagram/typical operating circuits ). the ac-coupling capacitor allows the device to bias the signal to an optimum dc level. assuming zero-source impedance, the -3db point of the highpass filter is given by: choose the c in such that f -3db is well below the lowest frequency of interest. setting f -3db too high affects the device? low-frequency response. use capacitors whose dielectrics have low-voltage coefficients, such as tantalum or aluminum electrolytic. capacitors with high-voltage coefficients, such as ceramics, can result in increased distortion at low frequencies. f rc db in in ? = 3 1 2 p tt disspkg max j max a ja () () = ? 60mw, directdrive, stereo headphone amplifiers with shutdown 8 _______________________________________________________________________________________
max9728a/max9728b 60mw, directdrive, stereo headphone amplifier with shutdown _______________________________________________________________________________________ 9 charge-pump capacitor selection use ceramic capacitors with a low esr for optimum performance. for optimal performance over the extend- ed temperature range, select capacitors with an x7r dielectric. table 1 lists suggested manufacturers. flying capacitor (c1) the value of the flying capacitor (see the functional diagram/typical operating circuits ) affects the charge pump? load regulation and output resistance. 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 resis- tance to an extent. see the output power vs. load resistance and charge-pump capacitor size graph in the typical operating characteristics . above 1?, the on-resistance of the switches and the esr of c1 and c2 dominate. hold capacitor (c2) the hold capacitor value (see the functional diagram/typical operating circuits ) and esr directly affect the ripple at pv ss . increasing the value of c2 reduces output ripple. likewise, decreasing the esr of c2 reduces both ripple and output resistance. lower capacitance values can be used in systems with low maximum output power levels. see the output power vs. load resistance and charge-pump capacitor size graph in the typical operating characteristics . power-supply bypass capacitor (c3) the power-supply bypass capacitor (see the functional diagram/typical operating circuits ) lowers the output impedance of the power supply, and reduces the impact of the max9728a/max9728bs?charge-pump switching transients. bypass v dd with c3, the same value as c1, and place it physically close to the v dd and pgnd pins. amplifier gain the gain of the max9728b amplifier is internally set to -1.5v/v. all gain-setting resistors are integrated into the device, reducing external component count. the inter- nally set gain, in combination with directdrive, results in a headphone amplifier that requires only five small capacitors to complete the amplifier circuit: two for the charge pump, two for audio input coupling, and one for power-supply bypassing (see the functional diagram/typical operating circuits ). the gain of the max9728a amplifier is set externally as shown in figure 2, the gain is: a v = -r f /r in (v/v) choose feedback resistor values in the tens of k range. lower values may cause excessive power dissi- pation and require impractically small values of r in for large gain settings. the high-impedance state of the outputs can also be degraded during shutdown mode if an inadequate feedback resistor is used since the equivalent output impedance during shutdown is 14k ||r f (r f is equal to 30k for the max9728b). the source resistance of the input device may also need to be taken into consideration. since the effective value of r in is equal to the sum of the source resistance of the input device and the value of the input resistor connect- ed to the inverting terminal of the headphone amplifier (20k for the max9728b), the overall closed-loop gain of the headphone amplifier can be reduced if the input resistor is not significantly larger than the source resis- tance of the input device. 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 murata 770-436-1300 770-436-3030 www.murata.com table 1. suggested capacitor manufacturers
max9728a/max9728b lineout amplifier and filter block the max9728a can be used as an audio line driver capable of providing 2v rms into 10k loads with a sin- gle 5v supply (see figure 3 for the rms output voltage vs. supply voltage plot). 2v rms is a popular audio line level, first used in cd players, but now common in dvd and set-top box (stb) interfacing standards. a 2v rms sinusoidal signal equates to approximately 5.7v p-p , which means that the audio system designer cannot simply run the lineout stage from a (typically common) 5v supply?he resulting output swing would be inade- quate. a common solution to this problem is to use op amps driven from split supplies (?v typically), or to use a high-voltage supply rail (9v to 12v). this can mean adding extra cost and complexity to the system power supply to meet this output level requirement. having the ability to derive 2v rms from a 5v supply can often sim- plify power-supply design in some systems. when the max9728a is used as a line driver to provide outputs that feed stereo equipment (receivers, stbs, notebooks, and desktops) with a digital-to-analog con- verter (dac) used as an audio input source, it is often desirable to eliminate any high-frequency quantization noise produced by the dac output before it reaches the load. this high-frequency noise can cause the input stages of the line-in equipment to exceed slew-rate lim- itations or create excessive emi emissions on the cables between devices. to suppress this noise, and to provide a 2v rms stan- dard audio output level from a single 5v supply, the max9728a can be configured as a line driver and active lowpass filter. figure 4 shows the max9728a connected as 2-pole rauch/multiple feedback filter with a passband gain of 6db and a -3db (below passband) cutoff frequency of approximately 27khz (see figure 5 for the gain vs. frequency plot). 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 pv ss to sv ss and bypass with a 1? capacitor. place the power-sup- ply bypass capacitor and the charge-pump hold capacitor as close to the max9728 as possible. route pgnd and all traces that carry switching transients away from sgnd and the audio signal path. the thin qfn package features an exposed paddle that improves thermal efficiency. ensure that the exposed paddle is electrically isolated from pgnd, sgnd, and v dd . connect the exposed paddle to sv ss only when the board layout dictates that the exposed paddle cannot be left floating. 60mw, directdrive, stereo headphone amplifiers with shutdown 10 ______________________________________________________________________________________ left audio input right audio input outl inl inr outr max9728a r in r in r f r f figure 2. gain setting for the max9728a rms output voltage vs. supply voltage max9728a/28b fig03 supply voltage (v) rms output voltage (v) 5.0 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 2.5 4.5 5.5 f in = 1khz r l = 10k 1% thd+n r l = 1k 1% thd+n figure 3. rms output voltage vs. supply voltage
max9728a/max9728b 60mw, directdrive, stereo headphone amplifier with shutdown ______________________________________________________________________________________ 11 max9728a active filter gain vs. frequency frequency (hz) gain (db) 100k 10k -30 -25 -20 -15 -10 -5 0 5 10 -35 1k 1m r l = 10k figure 5. frequency response of active filter of figure 4 left audio input right audio input outl inl inr outr max9728a 7.5k 7.5k 7.5k 7.5k 15k 10k 10k 15k 1.2nf 1.2nf 220pf 220pf line-in device stereo dac 1 f 1 f figure 4. max9728a line-out amplifier and filter block configuration
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 12 ______________________________________________________________________________________ max9710 outr+ outr- outl- outl+ inr inl bias pv dd v dd shdn 15k 15k 15k 15k v dd 0.1 f 1 f 0.1 f 1 f max9728b 0.1 f outl outr sgnd c1p c1n pgnd pv ss sv ss v dd shdn 1 f o.47 f o.47 f inl inr controller stereo dac 1 f 100k 100k v dd 1 f v dd mute pgnd gnd system diagram
max9728a/max9728b 60mw, directdrive, stereo headphone amplifier with shutdown ______________________________________________________________________________________ 13 charge pump uvlo/ shutdown control click-and-pop suppression c1n c1p pv ss sv ss pgnd sgnd *r in and r f values are chosen for a gain -1.5v/v. ( ) tssop package inr v dd shdn on off sv ss v dd sgnd inl r f * 30k r in * 20k r in * 20k outr left audio input right audio input headphone jack 5 (8) 12 (2) 1 (3) 2 (4) 3 (5) 4 (7) 9 (12) 11 (1) 6 (9) 10 (14) 7 (10) c1 1 f c2 1 f 4.5v to 5.5v c3 1 f c in 0.47 f sv ss v dd outl c in 0.47 f 8 (11) r f * 30k max9728a functional diagram/typical operating circuits
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 14 ______________________________________________________________________________________ charge pump uvlo/ shutdown control click-and-pop suppression c1n c1p pv ss sv ss pgnd sgnd ( ) tssop package inr v dd shdn sv ss v dd sgnd inl r f 30k r in 20k r in * 20k outr left audio input right audio input headphone jack 5 (8) 12 (2) 1 (3) 2 (4) 3 (5) 4 (7) 9 (12) 11 (1) 6 (9) 10 (14) 7 (10) c1 1 f c2 1 f 4.5v to 5.5v c3 1 f c in 0.47 f v ss v dd outl c in 0.47 f 8 (11) r f * 30k max9728b on off functional diagram/typical operating circuits (continued)
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown ______________________________________________________________________________________ 15 top view 12 11 10 4 5 6 123 987 max9728a max9728b tqfn c1p pgnd c1n pv ss shdn inl sgnd inr sv ss outr outl + v dd 14 13 12 11 10 9 8 1 2 3 4 5 6 7 outr n.c. sv ss inr pgnd c1p v dd outl top view max9728a max9728b sgnd inl shdn pv ss n.c. c1n tssop + pin configurations chip information transistor count: 993 process: bicmos
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 16 ______________________________________________________________________________________ package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. 12x16l qfn thin.eps 0.10 c 0.08 c 0.10 m c a b d d/2 e/2 e a1 a2 a e2 e2/2 l k e (nd - 1) x e (ne - 1) x e d2 d2/2 b l e l c l e c l l c l c package outline 21-0136 2 1 i 8, 12, 16l thin qfn, 3x3x0.8mm marking aaaa package type package code document no. 12 tqfn-ep t1233-1 21-0136 14 tssop u14-1 21-0066
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown ______________________________________________________________________________________ 17 exposed pad variations codes pkg. t1233-1 min. 0.95 nom. 1.10 d2 nom. 1.10 max. 1.25 min. 0.95 max. 1.25 e2 12 n k a2 0.25 ne a1 nd 0 0.20 ref - - 3 0.02 3 0.05 l e e 0.45 2.90 b d a 0.20 2.90 0.70 0.50 bsc. 0.55 3.00 0.65 3.10 0.25 3.00 0.75 0.30 3.10 0.80 16 0.20 ref 0.25 - 0 4 0.02 4 - 0.05 0.50 bsc. 0.30 2.90 0.40 3.00 0.20 2.90 0.70 0.25 3.00 0.75 3.10 0.50 0.80 3.10 0.30 pkg ref. min. 12l 3x3 nom. max. nom. 16l 3x3 min. max. 0.35 x 45 pin id jedec weed-1 t1233-3 1.10 1.25 0.95 1.10 0.35 x 45 1.25 weed-1 0.95 t1633f-3 0.65 t1633-4 0.95 0.80 0.95 0.65 0.80 1.10 1.25 0.95 1.10 0.225 x 45 0.95 weed-2 0.35 x 45 1.25 weed-2 t1633-2 0.95 1.10 1.25 0.95 1.10 0.35 x 45 1.25 weed-2 package outline 21-0136 2 2 i 8, 12, 16l thin qfn, 3x3x0.8mm weed-1 1.25 1.10 0.95 0.35 x 45 1.25 1.10 0.95 t1233-4 t1633fh-3 0.65 0.80 0.95 0.225 x 45 0.65 0.80 0.95 weed-2 notes: 1. dimensioning & tolerancing conform to asme y14.5m-1994. 2. all dimensions are in millimeters. angles are in degrees. 3. n is the total number of terminals. 4. the terminal #1 identifier and terminal numbering convention shall conform to jesd 95-1 spp-012. details of terminal #1 identifier are optional, but must be located within the zone indicated. the terminal #1 identifier may be either a mold or marked feature. 5. dimension b applies to metallized terminal and is measured between 0.20 mm and 0.25 mm from terminal tip. 6. nd and ne refer to the number of terminals on each d and e side respectively. 7. depopulation is possible in a symmetrical fashion. 8. coplanarity applies to the exposed heat sink slug as well as the terminals . 9. drawing conforms to jedec mo220 revision c. 10. marking is for package orientation reference only. 11. number of leads shown are for reference only. 12. warpage not to exceed 0.10mm. 0.25 0.30 0.35 2 0.25 0 0.20 ref - - 0.02 0.05 0.35 8 2 0.55 0.75 2.90 2.90 3.00 3.10 0.65 bsc. 3.00 3.10 8l 3x3 min. 0.70 0.75 0.80 nom. max. tq833-1 1.25 0.25 0.70 0.35 x 45 weec 1.25 0.70 0.25 t1633-5 0.95 1.10 1.25 0.35 x 45 weed-2 0.95 1.10 1.25 package information (continued) for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status.
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 18 ______________________________________________________________________________________ package information (continued) for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. tssop4.40mm.eps
max9728a/max9728b 60mw, directdrive, stereo headphone amplifiers with shutdown 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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 19 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 1/06 initial release 1 7/09 corrected top mark designations 1

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