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________________________________________________________________ _ maxim integrated products _ _ 1 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com. MAX13301 4-channel, automotive class d audio amplifier 19-5955; rev 0; 6/11 general description the MAX13301 combines four high-efficiency class d amplifiers with integrated diagnostic hardware for reli - able automotive audio systems, and delivers up to 80w at 10% thd+n per channel into 4 i when operating from a 24v supply. the internal diagnostics evaluate each channels output impedance to check for shorts across the outputs, to the battery, or to ground. the i 2 c interface allows the sys - tem to query critical device parameters such as device temperature and output clipping. the device is program - mable to four different i 2 c addresses. the audio amplifiers feature single-ended analog inputs with a common negative input. the MAX13301 has a fixed gain of 26db. the class d amplifier has 10 programmable switching frequencies between 300khz and 750khz. the btl outputs are protected against short circuits and thermal overload. the outputs can be configured as a 2-, 3-, or 4-channel amplifier. the device provides 50v load-dump protection, and is offered in the thermally enhanced, 48-pin tssop-epr package operating over the -40 n c to +125 n c temperature range. applications car stereo rear-seat entertainment units discrete amplifier modules active loudspeaker systems radio head units mobile surround systems features s high_ output_ power_ (10%_ thd+n) ? 2_ x_ 160w_ into_ 2 i _ at_ 24v ? 4_ x_ 80w_ into_ 4 i _ at_ 24v s 2_ channels_ can_ be_ paralleled s feedback_ after_ the_ filter ? improves_ thd+n ? low_ output_ impedance ? high-frequency_ response ? improved_ damping_ of_ complex_ loads ? enables_ low-cost_ inductors s 102db_ snr s low_ 0.04%_ thd+n s 70db_ psrr s on-board_ diagnostics ? short-to-battery/gnd ? open/shorted_ load ? tweeter_ detect s protection_ and_ monitoring_ functions: ? short-circuit_ protection ? 50v_ load-dump_ protection ? programmable_ clip_ detection ? dc_ offset_ detection ? open_ battery/gnd_ tolerant ? thermal-overload_ protection ? thermal_ warning_ indication s four-address_ i 2 c_ control_ interface s low-power_ shutdown_ mode s up_ to_ 90.5%_ efficiency s -40c_ to_ +125c_ ambient_ operating_ temperature s 48-pin _ tssop-epr _ (top _ side _ exposed _ pad) _ package s aec-q100_ qualified ordering information note: the device operates over the -40 c to +125 c operating temperature range. /v denotes an automotive qualified part. + denotes a lead(pb)-free/rohs-compliant package. * epr = top side exposed pad. typical operating circuit appears at end of data sheet. evaluation_kit available part pin-package supply_ voltage_ range_ (v) MAX13301aum/v+ 48 tssop-epr* 6 to 25.5
MAX13301 4-channel, automotive class d audio amplifier 2 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. pvdd to pgnd ...................................................... -0.3v to +30v pvdd to pgnd (t < 200ms) .................................. -0.3v to +50v pvdd ramp rate ........................................................... 25v/ms v dd5 , cm to pgnd ................................................. -0.3v to +6v cp to pgnd ........................ (v pvdd - 0.3v) to (v chold + 0.3v) chold to pvdd ..................................................... -0.3v to +6v out_ to pgnd, fb_ to pgnd .............. -0.3v to (v pvdd + 0.3v) v dd to gnd ............................................................ -0.3v to +6v ref to gnd ............................................................. -0.3v to +6v scl, sda, sync to gnd ........................................ -0.3v to +6v mute_cl1 , cl0 , flt_ot , en to gnd ................... -0.3v to +6v in_ to gnd .............................................................. -0.3v to +6v gnd to pgnd ...................................................... -0.3v to +0.3v continuous power dissipation (notes 1 and 2) tssop (derate 16.7mw/ n c above 70 n c) ............... 1333.3mw operating temperature range ........................ -40 n c to +125 n c junction temperature range ........................... -40 n c to +150 n c storage temperature range ............................ -65 n c to +150 n c lead temperature (soldering, 10s) ................................ +300 n c soldering temperature (reflow) ...................................... +240 n c tssop junction-to-ambient thermal resistance ( b ja ) .......... 60 n c/w junction-to-case thermal resistance ( b jc ) ................. 1 n c/w electrical_ characteristics (v pvdd = 14.4v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = (see table 20 for applicable setting), t a = -40 n c to +125 n c; typical values are at t a = +25 n c, unless otherwise noted.) (note 3) absolute_ maximum_ ratings package_ thermal_ characteristics_ (notes_ 1_ and_ 2) 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.maxim-ic.com/thermal-tutorial . note_ 2: the 48-pin tssop-epr package has a top side exposed pad for enhanced thermal management. connect this exposed pad to an external heatsink to ensure the device is adequately cooled. the maximum power dissipation in the device is a function of this external heatsink and other system parameters. see the thermal information section for more information. parameter symbol conditions min typ max units amplifier_ dc_ characteristics supply voltage range v pvdd 8 25.5 v operational 6 v dd5 4.75 5 5.5 v dd 4.5 5 5.5 pvdd uvlo threshold falling 5.2 5.35 5.6 v pvdd ovlo threshold rising 26 27 30 v pvdd ovlo response timing rising 4 14 55 f s out_ and fb_ voltage ov active v pvdd /2 v v dd uv threshold falling 4.2 4.35 v rising 4.5 4.6 v dd uv threshold hysteresis 0.1 0.2 v v dd uv threshold deglitch 1 f s quiescent supply current i pvdd r l = j , play mode (ctrl2 = 0x0f) 70 f a i vdd5 60 72 ma i vdd 50 75
MAX13301 4-channel, automotive class d audio amplifier 3 electrical_ characteristics_ (continued) (v pvdd = 14.4v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = (see table 20 for applicable setting), t a = -40 n c to +125 n c; typical values are at t a = +25 n c, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units pvdd shutdown supply current i pvdd_ shdn t a = +25 n c, v en = 0v 7 f a t a = t min to +85 n c, v en = 0v 17 v dd5 shutdown supply current i vdd5_ shdn t a = +25 n c, v en = 0v 0.1 f a t a = t min to +85 n c, v en = 0v 2 v dd shutdown supply current i vdd_shdn t a = +25 n c, v en = 0v 0.1 f a t a = t min to +85 n c, v en = 0v 2 standby supply current i vdd5 ctrl2 = 0x20, v en = 5v 1 ma i vdd 10 output leakage v out_ = 14.4v 200 f a v out_ = 0v 1 output discharge current ctrl3.dis = 1 8 ma r ds(on) per output excluding wire bond resistance 70 m i fb_ resistance 310 k i output offset v os t a = +25 n c, mute mode (ctrl2 = 0x00), no input signal 15 mv t a = t min to t max 100 out_ output impedance 100 m i amplifier_ ac_ characteristics output power p out thd+n = 1%, r l = 4 i , v pvdd = 24v 66 w thd+n = 10%, r l = 4 i , v pvdd = 24v 80 thd+n = 10%, r l = 2 i , v pvdd = 24v, parallel mode 160 signal-path gain 26 db channel-to-channel gain tracking -1 +0.1 +1 db input resistance in0+, in1+, in2+, in3+ 20 k i in- 5 mute attenuation guaranteed by design, test is functional only 90 100 db precharge current ctrl1.pre = 1 in- 5 10 ma in_+ 1 2 power-supply rejection ratio v dd = 4.5v to 5.5v 70 db v pvdd = 1v p-p ripple, 100hz to 10khz 60 v pvdd = 8v to 25.5v 68 ref voltage c ref(min) = 1f 2.224 v ref output impedance dc 800 i input voltage range ac-coupled 1.2 v rms
MAX13301 4-channel, automotive class d audio amplifier 4 electrical_ characteristics_ (continued) (v pvdd = 14.4v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = (see table 20 for applicable setting), t a = -40 n c to +125 n c; typical values are at t a = +25 n c, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units total harmonic distortion plus noise thd+n p out = 10w, r l = 4 i , bw = 22hz to 20khz aes17 filter, f = 1khz 0.04 0.14 % p out = 1w to 10w, r l = 4 i , bw = 22hz to 20khz aes17 filter, f = 1khz 0.1 noise n a-weighted, v pvdd = 24v 100 f v rms 22hz to 22khz, v pvdd = 24v 140 a-weighted, ctrl5.ss[2:0] = 110, ssen = 1, v pvdd = 24v 100 crosstalk p out_ = 4w, f = 1khz to 10khz 60 db efficiency e r l = 4 i , p out = 20w/channel, v dd5 , v dd supplied from a switching power supply 88 % internal switching frequency adjust range 6 to 15 clock-divider range 300 750 khz one-time_ diagnostics short-to-ground detection ctrl2.stby = 0, ctrl3.sdet = 1 75 i short-to-pvdd detection threshold ctrl2.stby = 1, ctrl3.sdet = 1 6 v open-load detection ctrl3.ldm = 1, power amplifier mode 70 100 i ctrl3.ldm = 0, line-driver mode 200 300 low-current threshold 15khz < f < 25khz, t a = +25 n c, ctrl3.tw = 1 ctrl3.hcl = 0 160 291 500 ma ctrl3.hcl = 1 200 364 625 high-current threshold f < 20hz, ctrl3.tw = 0 ctrl3.hcl = 0 0.65 1.15 1.85 a ctrl3.hcl = 1 0.9 1.65 2.15 continuous_ diagnostics differential output offset voltage threshold no audio in play mode 0.56 1.04 1.6 v clip-detect threshold r l = 4 i ctrl1.clvl[1:0] = 11 1 %thdn ctrl1.clvl[1:0] = 01 3 ctrl1.clvl[1:0] = 10 5 ctrl1.clvl[1:0] = 00 10
MAX13301 4-channel, automotive class d audio amplifier 5 electrical_ characteristics_ (continued) (v pvdd = 14.4v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = (see table 20 for applicable setting), t a = -40 n c to +125 n c; typical values are at t a = +25 n c, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units short-to-ground/pvdd out__ shorted to ground/pvdd, ctrl1.cl_th = 1 ctrl3.hcl = 0 1.03 a ctrl3.hcl = 1 1.28 out__ shorted to ground/pvdd, ctrl1.cl_th = 0 ctrl3.hcl = 0 3.09 ctrl3.hcl = 1 3.86 level 1 output current limit i lim1 ctrl3.hcl = 0 5.5 7 a level 2 output current limit i lim2 ctrl3.hcl = 1 7 8.75 a thermal_ protection thermal warning range 1 guaranteed monotonic 110 n c thermal warning range 2 guaranteed monotonic 120 n c thermal warning range 3 guaranteed monotonic 130 n c thermal warning range 4 guaranteed monotonic 140 n c thermal shutdown level guaranteed monotonic 150 165 n c thermal warning hysteresis 5 n c thermal shutdown hysteresis 15 n c charge_ pump switching frequency f cp = f sw 300 750 khz soft-start time 100 f s charge-pump output impedance guaranteed by fet r ds(on) measurement 1.8 i output voltage v pvdd + 5 v internal_ oscillator sync i/o frequency range 2x switching frequency 0.6 1.5 mhz frequency spread-spectrum disabled 17.1 18 18.9 mhz digital_ interface_ (scl,_ sda,_ addr,_ cl0 ,_ mute_cl1 ,_ en,_ sync,_ flt_ot ) sync high ctrl1.cm[1:0] = 01, i source = 3ma 4.5 v sync low ctrl1.cm[1:0] = 01, i sink = 3ma 0.4 v input voltage high v inh 2.0 v input voltage low v inl 0.8 v input voltage hysteresis 300 mv input leakage current sda, scl, cl0 , mute_cl1 , flt_ot q 10 f a output low voltage sda, cl0 , mute_cl1 , i sink = 3ma, flt_ot 0.4 v pulldown current mute_cl1 5 13 f a en 10 18
MAX13301 4-channel, automotive class d audio amplifier 6 note_ 3: all units are 100% production tested at t a = +25 n c. all temperature limits are guaranteed by design. electrical_ characteristics_ (continued) (v pvdd = 14.4v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = (see table 20 for applicable setting), t a = -40 n c to +125 n c; typical values are at t a = +25 n c, unless otherwise noted.) (note 3) parameter symbol conditions min typ max units i 2 c_ timing output fall time t of c bus = 10pf to 400pf 250 ns pin capacitance 10 pf clock frequency f scl 400 khz scl low time t low 1.3 f s scl high time t high 0.6 f s start condition hold time t hd:sta repeated start condition 0.6 f s start condition setup time t su:sta repeated start condition 0.6 f s data hold time t hd:dat 0 900 ns data setup time t su:dat 100 ns input rise time t r scl, sda 300 ns input fall time t f scl, sda 300 ns stop condition setup time t su:sto 0.6 f s bus free time t buf between start and stop conditions 1.3 f s maximum bus capacitance c bus per bus line 400 pf
MAX13301 4-channel, automotive class d audio amplifier 7 typical operating characteristics (v pvdd = 24v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = 011, see table 32 for lc filter value, t a = +25 n c, unless otherwise noted.) output frequency spectrum MAX13301 toc09 frequency (khz) amplitude (dbv) 15 10 5 -100 -80 -60 -40 -20 0 -120 0 20 mute mode r l = 4 i frequency (khz) crosstalk (db) 10 1 0.1 -90 -80 -70 -60 -50 -40 -100 0.01 100 crosstalk MAX13301 toc08 p out = 4w r l = 4 i out0 to out1 out0 to out3 out0 to out2 output power per channel(w) 10 20 30 40 50 60 70 80 90 100 0 output power vs. supply voltage MAX13301 toc07 v pvdd (v) 10 15 20 25 5 30 r l = 4 i f in = 1khz 1% thd+n 10% thd+n power dissipation vs. output power per channel MAX13301 toc06 output power per channel (w) power dissipation (w) 80 70 50 60 20 30 40 10 5 10 15 20 25 30 35 40 45 50 0 0 90 f in = 1khz r l = 4i 10% thd+n bw = 22hz to 20khz aes17 power dissipation vs. output power per channel MAX13301 toc05 output power per channel (w) power dissipation (w) 5 10 15 20 30 25 35 40 0 45 40 5 1 0 1 5 2 5 3 0 20 35 0 50 r l = 2i f in = 1khz 10% thd+n bw = 22hz to 20khz aes17 efficiency vs. output power per channel MAX13301 toc04 output power per channel (w) efficiency (%) 80 70 50 60 20 30 40 10 10 20 30 40 50 60 70 80 90 100 0 0 90 f in = 1khz r l = 4i 10% thd+n bw = 22hz to 20khz aes1 efficiency vs. output power per channel MAX13301 toc03 output power per channel (w) efficiency (%) 10 20 30 40 50 60 70 80 90 100 0 f in = 1khz 10% thd+n bw = 22hz to 20khz aes17 2-channel parallel mode r l = 1i r l = 4i r l = 2i 90 80 10 20 30 50 60 40 70 0 100 MAX13301 toc02 output power (w) 140 120 100 80 60 40 20 0 160 thd+n vs. output power thd+n (%) 0.1 1 10 0.01 f = 1khz bw = 22hz to 20khz aes17 parallel mode r l = 2 i r l = 4 i thd+n vs. output power MAX13301 toc01 output power (w) thd+n (%) 60 40 20 0.1 1 10 0.01 0 80 f = 1khz bw = 22hz to 20khz aes17 r l = 4 i
MAX13301 4-channel, automotive class d audio amplifier 8 typical operating characteristics (continued) (v pvdd = 24v, v dd = v dd5 = 5v, v gnd = v pgnd = 0v, f sw = 500khz, map.comp[2:0] = 011, see table 32 for lc filter value, t a = +25 n c, unless otherwise noted.) frequency (mhz) 10 1 0.1 100 spread-spectrum modulation wideband output spectrum MAX13301 toc13 ctrl5 = 0xb9 measured at out__ with -20db attenuation amplitude (dbv) -80 -70 -60 -50 -40 -30 -20 -10 -90 0 frequency (mhz) 10 1 0.1 100 spread-spectrum modulation wideband output spectrum MAX13301 toc12 ctrl5 = 0x09 measured at out__ with -20db attenuation amplitude (dbv) -80 -70 -60 -50 -40 -30 -20 -10 -90 0 frequency (mhz) 10 1 0.1 100 fixed-frequency modulation wideband output spectrum MAX13301 toc11 measured at out__ with -20db attenuation amplitude (dbv) -80 -70 -60 -50 -40 -30 -20 -10 -90 0 frequency response MAX13301 toc10 frequency (khz) response (db) 10 1 0.1 -2 -1 0 1 2 3 -3 0.01 100 p out = 30w r l = 2i c2 = 1f p out = 1w and 10w r l = 4i
MAX13301 4-channel, automotive class d audio amplifier 9 pin description pin configuration 48 47 46 45 44 43 42 41 40 39 1 2 3 4 5 6 7 8 9 10 pvdd cp chold cm fb3+ fb2- fb2+ pvdd top view MAX13301 v dd5 pgnd out1+ out1- out3- out3+ fb3- pgnd pgnd pgnd pgnd 38 37 36 35 34 33 32 31 30 29 pgnd pgnd out0+ out0- fb0+ fb0- fb1+ fb1- sda 11 12 13 14 15 16 17 18 19 out2- out2+ pgnd pgnd v dd gnd in- in1+ in0+ tssop 20 21 pvdd ref 24 28 25 scl 22 in2+ 27 en 23 in3+ 26 sync pvdd mute_cl1 flt_ot + epr cl0 pin name function 1, 24, 25, 48 pvdd audio output power-supply input. bypass each pvdd to its pgnd pair locally with 0.1 f f and 4.7 f f ceramic capacitors. each pvdd/pgnd pair consists of one pvdd and two pgnds. the pvdd/ pgnd pairs are 1 and 9-10, 48 and 39-40, 24 and 11-12, and 25 and 37-38. bypassing pvdd locally minimizes the area of di/dt loops. an additional 1000 f f, low-esr electrolytic capacitor should be placed from 1 and 48 to pgnd and 24 and 25 to pgnd. 2 fb2+ output 2 positive feedback. connect to the lc filters positive output through a 150 i 1% resistor. 3 fb2- output 2 negative feedback. connect to the lc filters negative output through a 150 i 1% resistor.
MAX13301 4-channel, automotive class d audio amplifier 10 pin description (continued) pin name function 4 fb3+ output 3 positive feedback. connect to the lc filters positive output through a 150 i 1% resistor. 5 fb3- output 3 negative feedback. connect to the lc filters negative output through a 150 i 1% resistor. 6 cl0 active-low open-drain clip 0 output. cl0 is configurable to provide clipping indication for outputs 0 and 1 or for all four outputs. 7 out3+ channel 3 power amplifier positive output 8 out3- channel 3 power amplifier negative output 9C12, 37C40, 43 pgnd audio output power ground 13 out2+ channel 2 power amplifier positive output 14 out2- channel 2 power amplifier negative output 15 mute_cl1 mute input or active-low open-drain clip 1 output. mute_cl1 is configurable as a mute input or as an open-drain clip indicator output. when configured as an input, drive mute_cl1 low to mute all four outputs. as an output, mute_cl1 provides clipping indication for outputs 2 and 3. this pin also selects the low bit of the i 2 c address and is latched upon the rising edge of the en pin. mute_cl1 has an internal 5 f a pulldown. 16 in- common audio negative input. in- has 5k i of input resistance. bypass to analog ground with 2f or 4 x c in_+ . 17 gnd analog ground 18 v dd 5v analog power-supply input. bypass with a 2.2 f f or larger ceramic capacitor to gnd. v dd provides power to the analog and digital circuitry. 19 in0+ channel 0 audio input. in0+ has 20k i of input resistance. connect a series capacitor of at least 0.47 f f to in0+. 20 in1+ channel 1 audio input. in1+ has 20k i of input resistance. connect a series capacitor of at least 0.47 f f to in1+. 21 ref 2.2v reference output. bypass ref to gnd with a 1 f f ceramic capacitor. 22 in2+ channel 2 audio input. in2+ has 20k i of input resistance. connect a series capacitor of at least 0.47 f f to in2+. 23 in3+ channel 3 audio input. in3+ has 20k i of input resistance. connect a series capacitor of at least 0.47 f f to in3+. 26 sync sync i/o. in master mode, sync outputs a clock signal that is synchronized to that of the modulator. in slave mode, sync is a clock input and serves as the clock source for the modulator. 27 en enable input. connect en to v dd for normal operation. connect en to gnd to place the device in a low-power mode. there is an internal 10a pulldown on en. 28 scl i 2 c serial-clock input 29 sda i 2 c serial-data input and output 30 fb1- output 1 negative feedback. connect to the lc filters negative output through a 150 i 1% resistor. 31 fb1+ output 1 positive feedback. connect to the lc filters positive output through a 150 i 1% resistor. 32 fb0- output 0 negative feedback. connect to the lc filters negative output through a 150 i 1% resistor. 33 fb0+ output 0 positive feedback. connect to the lc filters positive output through a 150 i 1% resistor.
MAX13301 4-channel, automotive class d audio amplifier 11 pin description (continued) functional diagram osc v dd5 analog audio interface class d output stage 0 and diags analog modulator and diagnostics registers and system control in_+ in- v dd gnd ref v dd5 pgnd i 2 c control interface gate driver 0 scl sda fb0+ fb0- lpf feedback diff. amp pvdd out0+ out0- pgnd en sync clo mute_cl1 flt_ot v dd5 class d output stage 3 and diags gate driver 3 pvdd out3+ out3- pgnd fb3+ fb3- lpf feedback diff. amp cp cm charge pump chold MAX13301 pin name function 34 flt_ot active-low open-drain fault and overtemperature output. flt_ot provides indication of faults, overtemperature, and thermal shutdown status. 35 out0- channel 0 power amplifier negative output 36 out0+ channel 0 power amplifier positive output 41 out1- channel 1 power amplifier negative output 42 out1+ channel 1 power amplifier positive output 44 v dd5 5v power-supply input. bypass with a 0.1 f f capacitor to pgnd. v dd5 provides power to the gate drivers and charge pump. 45 cm charge-pump capacitor negative terminal 46 chold charge-pump output. connect a 1 f f capacitor from chold to pvdd. 47 cp charge-pump capacitor positive terminal epr top side exposed pad. connect this exposed pad to an external heatsink to ensure the device is adequately cooled. the maximum power dissipation in the device is a function of this external heatsink and other system parameters. see the thermal information section for more information. the top side exposed pad is electrically isolated from the die.
MAX13301 4-channel, automotive class d audio amplifier 12 detailed description the MAX13301 4-channel, class d audio power ampli - fiers is specifically designed for automotive applications. integrated feedback from the lc filters output improves the thd+n by reducing the distortion, providing class ab performance while achieving efficiency up to 90.5%. the devices also support spread-spectrum modulation for am radio compatibility. description of operation the device emulates current-mode controllers with digital feed-forward (figure 1). the internal oscillator creates an 18mhz square wave. the i 2 c controls a clock divider that divides down this high-frequency clock to a usable fre - quency. the resulting square wave is integrated to create a triangle wave. a 3-bit adc converts the pvdd voltage into a code that adjusts the resistors used in the triangle- wave integrator. the triangle-wave amplitude becomes progressively larger as pvdd increases. the triangle wave is fed into the pwm comparator. the two differential amplifiers provide both analog and digital feedback. the feedback is summed with the out - put of the preamplifier at the error amplifier. the output of the error amplifier is an ac replica of the inductor cur - rent (emulated current mode) and the triangle wave is therefore the slope compensation. the pwm comparator controls the full-bridge operation, turning on and off each fet pair (double-edge modulation). to ensure that the devices switch at the desired frequency, it is important to ensure that the triangle wave is greater than the error- figure 1. detailed block diagram of the MAX13301 audio path pwm logic triangle wave i 2 c comp preamplifier osc ref ref ref ref ref audio in pvdd 3-bit adc feed- forward error amplifier pwm comparator i 2 c comp
MAX13301 4-channel, automotive class d audio amplifier 13 amplifier ramp. the design equation that must be met to ensure constant frequency is as follows: error-amplifier ramp < 2/3 triangle-wave ramp the error-amplifier ramp is fixed by the gain of the dif - ferential amplifiers used in the feedback loop and by the error-amplifier compensation capacitor programmed through i 2 c. to ensure the design equation for fixed fre - quency is met, the error-amplifier compensation capaci - tor tracks the integrator capacitor used to generate the triangle wave. for optimal noise shaping, the error-amplifier capaci - tor should be set to a small value. this results in a broadband spectrum where the error amplifier pushes the noise created by the clock jitter and pwm sam - pling above the audio range. however, there is a limit. because the triangle-wave capacitor tracks the error- amplifier capacitor, small capacitor values can clip the triangle wave as it runs out of supply. this effect is aggravated at high pvdd voltages by the adc action that decreases the integrator resistor at higher supply voltages. tables 20 and 21 are lookup tables to facili - tate choosing the optimal setting for the error-amplifier capacitance (map.comp[2:0]). it is possible to change this setting instantaneously while playing music, but if there is no music, a slight audible click is heard at the speakers. systems that monitor the input voltage can take advantage of this instanta - neous programmability and use a smaller error-amplifier capacitor at lower pvdd voltages. higher switching frequencies also allow the use of a smaller integrator capacitor, and thus help improve the noise performance of the amplifier. do not set the error-amplifier capacitor to a value less than 18pf. doing so results in extreme distortion, as the triangle wave clips. the map.comp[2:0] settings that result in this behavior are listed as reserved (table 19). advantage of feedback after the filter high-fidelity audio amplifiers require very low output impedance. the device achieves this by using a dual- feedback approach. the digital feedback (feedback from out__ outputs) emulates current-mode enabling on chip compensation. the analog feedback (fb__ inputs) significantly reduces the output impedance of the ampli - fier and at the same time, compensates for the nonideal characteristics of the output filter. if the characteristics of the speaker and/or output filter change with age or temperature, the analog feedback compensates accord - ingly. further inductor matching is less critical because the inductors are inside the feedback loop. because the inductors are inside the feedback loop, the loop can dampen out any lc ringing that might occur when the amplifier is used as a line driver. the analog feedback is differential so it does not help with common-mode ring - ing. thus, the zobel (rc) networks are required on each speaker connection to damp any common-mode ringing associated with the lc output filter and speaker. operating modes configure the device for one of three states of activity: normal, standby, or shutdown. normal in normal mode, the device is ready for play. placing the device in standby reduces power consumption while keeping fault monitors and the i 2 c interface on to com - municate fault conditions. in shutdown, the device is completely disabled and draws minimal current from the battery. to reset the device and clear all register contents to their reset values, set ctrl5.rst to 1. after reset, this bit is automatically cleared back to 0. standby in standby, all circuitry is disabled except the fault moni - tors and the i 2 c interface. the i 2 c registers retain their content and are still interactive. to place the device in standby, set the ctrl2.stby bit to 1. in standby, the device draws 11ma from all power-supply inputs. before exiting standby, always set the ctrl1.cl_th (cur - rent-limit threshold setting) bit to 1. after exiting standby, clear ctrl1.cl_th back to 0. table_ 1._ operating_ modes x = dont care mode en ctrl2.stby i 2 c fault_ monitors all_ other_ circuitry normal high 0 enabled on on standby high 1 enabled on off shutdown low x off off off
MAX13301 4-channel, automotive class d audio amplifier 14 shutdown in shutdown, all circuitry including the fault monitors and i 2 c interface is disabled to reduce power consumption and extend battery life. connect en to logic-high for nor - mal operation. connect en to gnd to place the device in a low-power shutdown mode. in shutdown, the devices draw 17ma (typ) from the battery. clock source the device supports fixed-frequency modulation with an internal or external clock. the modulation mode is select - ed through ctrl1.cm[1:0] (operating mode select bits). master configuration in master mode, 10 modulation frequencies are avail - able in fixed-frequency modulation mode. program ctrl0.mdiv[3:0] (master clock-divide ratio bits) for the desired frequency. slave configuration configuring the device as a slave allows an external clock source to provide the switching frequency. in this case, apply the external clock signal at sync at double the desired switching frequency. fixed-frequency modulation mode the devices supports a fixed-frequency modulation mode with 10 different selectable frequencies between 300khz and 750khz. the frequency is selectable through the i 2 c interface. the frequency spectrum consists of the fundamental switching frequency and its associated harmonics (see the wideband output spectrum graphs in the typical operating characteristics ). for applications where exact spectrum placement of the switching funda - mental is important, program the switching frequency so that the harmonics do not fall within a sensitive frequency band. spread spectrum the device features a unique spread-sprectrum mode that flattens the wideband spectral components, improv - ing emi emissions that can be radiated by the speaker and cables. this feature is only available in master clock mode and is enabled by setting the ctrl5.ss[2:0] and ctrl5.ssen bits. in spread-spectrum mode, the switch - ing frequency vaies linearly by up to 7% depending on ctrl5.ss[2:0] setting. the modulation scheme remains the same, but the period of the triangle waveform changes from cycle to cycle. instead of a large amount of spectral energy present at multiples of the switching frequency, the energy is now spread over a bandwidth that increases with frequency. above a few megahertz, the wideband spectrum looks like white noise for emi purposes. a proprietary amplifier topology ensures this does not significantly increase the noise floor in the audio bandwidth. efficiency the high efficiency of a class d amplifier is due to the switching operation of the output stage transistors. in a class d amplifier, the output transistors act as current- steering switches and consume negligible additional power. any power loss associated with the class d output stage is mostly due to the i 2 r loss of the mosfet on-resistance and quiescent current overhead. the theoretical best efficiency of a linear amplifier is 78% at peak output power. under normal operating levels (typi - cal music reproduction levels), the efficiency falls below 30%, whereas the device exhibits > 80% efficiency under the same conditions (figure 2). current limit the current limit of the outputs is selectable between 7a (typ) and 8.75a (typ) through the ctrl3.hcl bit. when the current limit is exceeded, the affected output is latched off and its corresponding overcurrent indica - tor bit ostat0. oc[3:0] is set to 0. the device does not attempt to activate the output until instructed by the microcontroller to do so. after eliminating the cause of the current limit, reactivate the output by setting ostat0. oc[3:0] to 1. short to either ground or battery causes the output to be latched off and its corresponding ostat0. oc[3:0] bit to be set to 0. after removing the short, reactivate the output by setting ostat0. oc[3:0] to 1. figure 2. efficiency vs. output power of class ab amplifier and the MAX13301 MAX13301 efficiency vs. ideal class ab amplifier efficiency output power per channel (w) efficiency (%) 20 15 10 5 10 20 30 40 50 60 70 80 90 100 0 0 25 v pvdd = 14.4v r l = 4i MAX13301 ideal class ab amplifier
MAX13301 4-channel, automotive class d audio amplifier 15 the device has real-time current limit for shorted outputs, outputs shorted to battery, outputs shorted to ground, and outputs shorted to adjacent channels. for shorted outputs, the devices enter cycle-by-cycle current limit. in a btl configuration, current flows diagonally through two of the four fets at any instant in time. if the current in either of these fets reaches the current-limit threshold, then both turn off and the other pair of diagonal fets turns on for a fixed time. this creates distortion, as the music clips. the internal logic of the device counts the cycle-by-cycle current- limit events, and if too many happen in a fixed amount of time, the devices latch off the faulted channel. current limit is programmable with the i 2 c. when ctrl3.hcl = 1, the peak current is limited to 8.75a (typ). with ctrl3.hcl = 0, peak current is limited to 7a (typ). short-to-battery and short-to-ground take advantage of the diagonal flow of current in a full bridge to detect fault conditions. the load current during normal opera - tion should be equal in the two diagonal fets that are actively conducting current. when an output is shorted to battery or ground, the current is no longer equal and the degree of mismatch is a measure of the severity of the fault. if the mismatch threshold is exceeded in any channel, that channel is immediately shut down and an overcurrent fault is reported. the level of mismatch is programmable through i 2 c. when ctrl1.cl_th = 0, the mismatch threshold is 3.09a with ctrl3.hcl = 0 and 3.86a with ctrl3.hcl = 1. when ctrl1.cl_th = 1, the mismatch threshold is 1.03a with ctrl3.hcl = 0 and 1.28a with ctrl3.hcl = 1. the lower setting is pre - ferred in that it can detect a misconfigured speaker. for example, the lower setting issues a fault if a 4 i speaker is incorrectly connected between one of the outputs and ground. at startup, when a large snubber capacitor is present, the higher setting is sometimes required to avoid false trips. when the bridge starts switching, both snubber capacitors must be charged to half the battery. the charging current mimics a short to ground. following the startup procedure is the best way to avoid issues with overcurrent faults. mute/precharging the device features a clickless/popless mute mode. when muted, the volume at the speaker is reduced to an inaudible level. to mute the device, configure mute_cl1 as a mute input by setting map.mclp (clip output map - ping bit) to 0. then drive the mute input low. use the mute function during system power-up and power-down to ensure optimum click-and-pop performance. it is also advisable to set ctrl1.pre (precharge bit) to 1 after taking the device out of standby mode to pre - charge the input dc-blocking capacitors. this action should be part of any startup routine. precharging the dc-blocking capacitors enhances click-and-pop perfor - mance. capacitors that are 0.47f/2f in series with the inputs take about 1ms to be charged. output configuration the four fets forming the full-bridge output of each channel can be programmed into one of four states: high-impedance (default), forced overvoltage, mute, and play through the ctrl2.md01_[1:0] (channels 0 and 1 output mode) and ctrl2.md23_[1:0] (channels 2 and 3 output mode) bits. channels 0 and 1 and channels 2 and 3 always share the same configuration. in high-impedance mode, all four fets are turned off. in forced overvoltage state, each half-bridge output is reg - ulated to 1/2 v pvdd . in mute mode, the outputs continue to switch but the volume is kept to an inaudible level. in play mode, the fets switch normally. i 2 c interface the device features an i 2 c, 2-wire serial interface con - sisting of a serial-data line (sda) and a serial-clock line (scl). sda and scl facilitate communication between the device and the master at clock rates up to 400khz. when the device is used on an i 2 c bus with multiple devices, the v dd supply must stay powered on to ensure proper i 2 c bus operation. the master, typically a micro - controller, generates scl and initiates data transfer on the bus. figure 3 shows the 2-wire interface timing diagram. a master device communicates to the ic by transmitting the proper address followed by the data word. each transmit sequence is framed by a start (s) or repeated start (sr) condition, and a stop (p) condition. each word transmitted over the bus is 8 bits long and is always followed by an acknowledge clock pulse. the sda line operates as both an input and an open- drain output. a pullup resistor, greater than 500 i , is required on the sda bus. the scl line operates as an input only. a pullup resistor, greater than 500 i , is required on scl if there are multiple masters on the bus, or if the master in a single-master system has an open- drain scl output. series resistors in line with sda and scl are optional. the scl and sda inputs suppress noise spikes to ensure proper device operation even on a noisy bus.
MAX13301 4-channel, automotive class d audio amplifier 16 bit transfer one data bit is transferred during each scl cycle. the data on sda must remain stable during the high period of the scl pulse. changes in sda while scl is high are control signals (see the start and stop conditions sec - tion). sda and scl idle high when the i 2 c bus is not busy. stop and start conditions a master device initiates communication by issuing a start condition. a start condition is a high-to-low transition on sda with scl high. a stop condition is a low-to-high transition on sda while scl is high (figure 4). a start condition from the master signals the beginning of a transmission to the device. the master terminates transmission and frees the bus by issuing a stop condi - tion. the bus remains active if a repeated start condi - tion is generated instead of a stop condition. early stop condition the device recognizes a stop condition at any point dur - ing data transmission, except if the stop condition occurs in the same high pulse as a start condition. slave address each time the device is enabled, the state of the mute_cl1 input is latched and determines the devices slave address. table 2 shows the two possible hard - ware-defined slave addresses of the devices. once the device is enabled, it is programmable to one of four i 2 c slave addresses through ctrl4.addr[1:0] (i 2 c slave address setting bits), as shown in table 3. when initially setting the slave address, use the default slave address as discussed in the previous paragraph and shown in table 2. after setting the slave address, set the ctrl5.addr_def (i 2 c slave address definition bit) to 1. for subsequent reads and writes, use the new software- defined address. these slave addresses are unique device ids. the address is defined as the 7 most significant bits (msbs) followed by the r/ w bit. set the r/ w bit to 1 to configure the device to read mode. set the r/ w bit to 0 to configure the device to write mode. the address is the first byte of information sent to the device after the start condition. figure 3. 2-wire serial-interface timing diagram figure 4. start, stop, and repeated start conditions scl sda start condition stop condition repeated start condition start condition t hd:sta t su:sta t hd:sta t sp t buf t su:sto t low t su:dat t hd:dat t high t r t f s p sr scl sda
MAX13301 4-channel, automotive class d audio amplifier 17 acknowledge the acknowledge bit (ack) is a clocked 9th bit that the device uses to handshake receipt each byte of data (figure 5). the device pulls down sda during the mas - ter-generated 9th clock pulse. the sda line must remain stable and low during the high period of the acknowl - edge clock pulse. monitoring ack allows for detection of unsuccessful data transfers. an unsuccessful data transfer occurs if a receiving device is busy or if a system fault has occurred. in the event of an unsuccessful data transfer, the bus master can reattempt communication. write data format a write to the device includes transmission of a start con - dition, the slave address with the write bit set to 0, one byte of data to register address, one byte of data to the com - mand register, and a stop condition. figure 6 illustrates the proper format for one frame. read data format a read from the device includes transmission of a start condition, the slave address with the write bit set to 0, one byte of data to register address, restart condition, the slave address with read bit set to 1, one byte of data to the com - mand register, and a stop condition. figure 6 illustrates the proper format for one frame. table_ 2._ default_ slave_ address table_ 3._ i 2 c_ programmable_ slave_ address figure 5. acknowledge condition figure 6. data format of i 2 c interface write mode read mode 1 2 8 9 acknowledge scl s sda slave address (write address) slave address (write address) register address data s a a p a slave address (read address) s = start condition, a = acknowledge, na = not acknowledge sr = repeated start condition, p = stop condition register address s a a s r p a data na mute_cl1 a6 a5 a4 a3 a2 a1 a0 r/ w write read low 1 1 0 1 1 0 1 x 0xda 0xdb high 1 1 0 1 1 0 0 x 0xd8 0xd9 ctrl4. _ addr[1:0] a6 a5 a4 a3 a2 a1 a0 r/ w write read 00 1 1 0 1 1 0 0 x 0xd8 0xd9 01 1 1 0 1 1 1 0 x 0xdc 0xdd 10 1 1 0 1 1 0 1 x 0xda 0xdb 11 1 1 0 1 1 1 1 x 0xde 0xdf
MAX13301 4-channel, automotive class d audio amplifier 18 register map table_ 4._ register_ map table_ 5._ control_ register_ 0 table_ 6._ control_ register_ 0_ bit_ description register bit_ 7 bit_ 6 bit_ 5 bit_ 4 bit_ 3 bit_ 2 bit_ 1 bit_ 0 address r/w power-on_ reset_ (por) ctrl0 mdiv3 mdiv2 mdiv1 mdiv0 tw1 tw0 0x00 r/w 0x24 ctrl1 cl_th clvl1 clvl0 pre cm1 cm0 0x01 r/w 0x00 ctrl2 stby md23_1 md23_0 md01_1 md01_0 0x02 r/w 0x20 ctrl3 tw rdet sdet dis hcl ldm 0x03 r/w 0x00 ctrl4 addr1 addr0 0x04 r/w 0xc0 ctrl5 ssen rst ss2 ss1 ss0 par1 par0 addr_def 0x05 r/w 0x01 map comp2 comp1 comp0 otwm lctm mclp otm fltm 0x06 r/w 0x40 stat ot otw ov uv oc cpuv clip 0x07 r ostat0 oc3 oc2 oc1 oc0 clip3 clip2 clip1 clip0 0x08 r ostat1 ldok3 ldok2 ldok1 ldok0 load3 load2 load1 load0 0x09 r ostat2 sbat3 sbat2 sbat1 sbat0 sgnd3 sgnd2 sgnd1 sgnd0 0x0a r ostat3 ver vos3 vos2 vos1 vos0 0x0b r ctrl0 bit_ # 7 6 5 4 3 2 1 0 name mdiv3 mdiv2 mdiv1 mdiv0 tw1 tw0 por 0 0 1 0 0 1 0 0 bit bit_ description mdiv[3:0] master clock-divide ratio. in master mode, the modulation and charge-pump frequencies are each set to 4.5mhz/(mdiv[3:0]). the device is in standby mode for mdiv[3:0] 3. the valid operating frequencies are 750khz, 642.9khz, 562.5khz, 500khz, 450khz, 409.1khz, 375khz, 346.2khz, 321.4khz, and 300khz. switching frequencies below 450khz compromises noise, as a larger integrator and triangle-wave capacitor trim setting is required. in slave mode, the modulation and charge-pump frequency are always set to f sync /2, where f sync is the frequency of the clock signal applied to the sync input. tw[1:0] thermal warning threshold. this threshold determines the temperature at which the status bit stat. otw asserts. 00 = junction temperature exceeds 110 n c. 01 = junction temperature exceeds 120 n c. 10 = junction temperature exceeds 130 n c. 11 = junction temperature exceeds 140 n c.
MAX13301 4-channel, automotive class d audio amplifier 19 table_ 8._ control_ register_ 1_ bit_ description table_ 7._ control_ register_ 1 ctrl1 bit_ # 7 6 5 4 3 2 1 0 name cl_th clvl1 clvl0 pre cm1 cm0 por 0 0 0 0 0 0 0 0 bit bit_ description cl_th selects the current threshold for the real-time short-to-ground and short-to-battery detection diagnostics. set this bit to 0 before exiting high-z mode to prevent false triggering of short-to-ground and short-to-battery faults during startup. set this bit to 1 after the device has entered mute or play mode. 0 = high threshold 1 = normal threshold clvl[1:0] clip level. the clip level provides an indication of the amount of total harmonic distortion in the output signal. 00 = thd exceeds 10% 10 = thd exceeds 5% 01 = thd exceeds 3% 11 = thd exceeds 1% pre precharge. use pre to precharge the input dc-blocking capacitors. set this bit to 1 as part of the startup procedure. a 2 f f capacitor for in- and 0.47 f f input blocking capacitors require a 1ms precharge to avoid startup pop. 0 = disable precharging 1 = enable precharging cm[1:0] clock mode. before selecting the operating mode, three-state all outputs. 00 = master fixed frequency, switching frequency set by the master clock-divide ratio (ctrl0.mdiv[3:0]) bits, sync output disabled 01 = master fixed frequency, switching frequency set by the master clock-divide ratio (ctrl0.mdiv[3:0]) bits, sync output enabled 10 = reserved 11 = slave fixed frequency, sync input enabled
MAX13301 4-channel, automotive class d audio amplifier 20 table_ 9._ control_ register_ 2 table_ 10._ control_ register_ 2_ bit_ description ctrl2 bit_ # 7 6 5 4 3 2 1 0 name stby md23_1 md23_0 md01_1 md01_0 por 0 0 1 0 0 0 0 0 bit bit_ description stby standby mode. wait 50ms after exiting standby mode to allow the charge pump and reference to stabilize before entering mute or play mode. 0 = normal mode 1 = standby mode. the charge pump, preamplifier, and modulator are disabled. fault monitors and i 2 c are still active. md23_[1:0] channels 2 and 3 output mode. channels 2 and 3 are always in the same configuration. md23_[1:0] determines the state of outputs 2 and 3. 00 = high-z 01 = mute 10 = forced overvoltage. in this state, both differential outputs are charged to 1/2 v pvdd . 11 = play md01_[1:0] channels 0 and 1 output mode. channels 0 and 1 are always in the same mode. md01_[1:0] determines the state of outputs 0 and 1. 00 = high-z 01 = mute 10 = force overvoltage. in this state, both differential outputs are charged to 1/2 v pvdd . 11 = play
MAX13301 4-channel, automotive class d audio amplifier 21 table_ 11._ control_ register_ 3 table_ 12._ control_ register_ 3_ bit_ description ctrl3 bit_ # 7 6 5 4 3 2 1 0 name tw rdet sdet dis hcl ldm por 0 0 0 0 0 0 0 0 bit bit_ description tw tweeter-detect current threshold setting 0 = the current threshold at which ostat1. load[3:0] (load indicator bit) asserts is set equal to the shorted- load current threshold (see the electrical characteristics table). use this setting when running shorted-load diagnostic. 1 = the current threshold at which ostat1. load[3:0] asserts is set equal to the tweeter detect current threshold. this threshold is approximately 25% of the default value to facilitate tweeter detection. use this setting when the running tweeter diagnostic or for detecting the presence of a speaker. rdet open-load diagnostic enable. upon detecting an open load on any of the outputs, the corresponding ostat1. ldok[3:0] (load ok indicator bit) asserts. always perform short-to-ground and short-to-battery diagnosis before entering rdet mode. if a short-to-battery is detected, do not enter rdet mode. after performing the short-to-battery test, discharge both outputs by setting ctrl3.dis to 1 for 200s, then reset ctrl3.dis back to 0. failure to follow this procedure can result in a loud pop at the speaker. because the results are not latched, read ldok[3:0] before clearing rdet. wait a minimum of 200s before reading these status bits. rdet can only be set after three-stating all four outputs. when performing the open-load diagnostic, set the ctrl3.sdet (short-to-ground/battery enable) bit to 0. 0 = disable open-load diagnostic 1 = enable open-load diagnostic sdet short-to-ground/battery diagnostic enable. upon detecting a short-to-ground or battery on any of the outputs, the corresponding ostat2. sbat[3:0] (short-to-battery) and ostat2. sgnd[3:0] (short-to-ground) bits assert. because the results are not latched, read ostat2. sbat[3:0] and ostat2. sgnd[3:0] before clearing sdet. wait a minimum of 200s before reading these status bits. before setting sdet to 1, three-state all four out - puts and set the ctrl3.dis (discharge output enable) bit to 1 and then reset back to 0. before performing the short-to-ground/battery diagnostic, set the ctrl3.rdet (open-load diagnostic enable) bit to 0. to test for short-to-ground, set ctrl2.stby to 0, and to test for short-to-battery, set ctrl2.stby to 1. 0 = disable short-to-ground/battery diagnostic 1 = enable short-to-ground/battery diagnostic dis discharge output enable. set dis to 1 to discharge all outputs with 15ma current sources. use dis to dis - charge all outputs before performing the short-to-ground/battery diagnostic (sdet) to avoid a loud pop on the speaker. dis can only be set to 1 after three-stating all four outputs. 0 = output discharge is disabled. 1 = output discharge is enabled. hcl current-limit level. hcl sets the current-limit threshold of the outputs during normal operation. 0 = 7a (typ) current limit 1 = 8.75a (typ) current limit ldm line-driver mode. use ldm to set the load resistance threshold required to assert the ostat1. ldok[3:0] (load-okay indicator bit). any load with a resistance greater than the threshold is interpreted as an open output. 0 = line-driver mode, ostat1. ldok[3:0] = 1 if r l > 300 i 1 = power amplifier mode, ostat1. ldok[3:0] = 1 if r l > 100 i
MAX13301 4-channel, automotive class d audio amplifier 22 table_ 13._ control_ register_ 4 table_ 14._ control_ register_ 4_ bit_ description ctrl4 bit_ # 7 6 5 4 3 2 1 0 name addr1 addr0 por 1 1 0 0 x x x x bit bit_ description addr[1:0] i 2 c slave address setting. use addr[1:0] to set the slave address of the device. after setting the slave address, set ctrl5.addr_def (i 2 c slave address definition bit) to 1 to make the new address effective. 00 = slave address set to 1101100 r/ w 01 = slave address set to 1101110 r/ w 10 = slave address set to 1101101 r/ w 11 = slave address set to 1101111 r/ w
MAX13301 4-channel, automotive class d audio amplifier 23 table_ 15._ control_ register_ 5 table_ 16._ control_ register_ 5_ bit_ description table_ 17._ spread-spectrum_ modulation_ table ctrl5 bit_ # 7 6 5 4 3 2 1 0 name ssen rst ss2 ss1 ss0 par1 par0 addr_def por 0 0 0 0 0 0 0 1 bit bit_ description ssen spread-spectrum modulation enable. 0: spread-spectrum disabled; ssen = 1 and ss[2:0] > 0: spread-spectrum enabled rst reset. setting rst to 1 resets the device. in reset, all register bits are reset to their por values. rst is auto - matically cleared back to 0 after device reset. 0 = not in reset 1 = reset ss[2:0] spread-spectrum modulation control. spread-spectrum modulation is enabled when ssen = 1 and ss[2:0] > 0, once enabled the switching frequency varies from +2% to +7% (see table 17). par[1:0] parallel mode. the four outputs can be paralleled in one of four ways. to parallel outputs, connect the posi - tive outputs together and connect the negative outputs together. in parallel mode, only the feedback inputs corresponding to the slaved input in0+ or in2+ are used. connect the other feedback inputs to ground. 00 = 4-channel output 01 = 2.1-channel output. outputs 0 and 1 are paralleled and slaved to input in0+. channels 2 and 3 are unaffected. 10 = 2.1-channel output. outputs 2 and 3 are paralleled and slaved to input in2+. channels 0 and 1 are unaffected. 11 = 2-channel output. outputs 0 and 1 are paralleled and slaved to input in0+. outputs 2 and 3 are paral - leled and slaved to input in2+. addr_def i 2 c slave address definition. this bit determines whether the i 2 c slave address is hardware or software- defined. 0 = slave address is defined by ctrl4.addr[1:0] (i 2 c slave address setting bits). 1 = slave address is set to the default address as defined by the state of the mute_cl1 input when the enable input en is pulled high. ssen ss2 ss1 ss0 spread_ (%) 0 x x x disabled 1 0 0 0 0 1 0 0 1 2 1 0 1 0 3 1 0 1 1 4 1 1 0 0 5 1 1 0 1 6 1 1 1 0 7 1 1 1 1 reserved
MAX13301 4-channel, automotive class d audio amplifier 24 table_ 18._ mapping_ register table_ 19._ mapping_ register_ bit_ description map bit_ # 7 6 5 4 3 2 1 0 name comp2 comp1 comp0 otwm lctm mclp otm fltm por 0 1 0 0 0 0 0 0 bit bit_ description comp[2:0] integrator and triangle-wave capacitor trim. a smaller integrator capacitor pushes noise out of the audio band yielding the lowest noise. if distortion rises at high output powers, lower switching frequencies, or higher pvdd voltages then use a larger capacitor setting. see table 20 for choosing minimum capacitor settings based on pvdd and the switching frequency. larger capacitor values can be used. if all 4 channels of the amplifier are used to drive subwoofers, the capacitor settings can be relaxed because a smaller capacitor setting helps to eliminate high-frequency noise (greater than 10khz). systems with multiple tweeters benefit the most from proper comp[2:0] selection. lower switching frequencies are possible when this high-frequency noise is not a concern as with systems that lack tweeters. 000 = 43pf 001 = 37pf 010 = 31pf 011 = 25pf 100 = 18pf 101 = reserved 110 = reserved 111 = reserved otwm overtemperature warning mapping bit 0 = stat. otw (overtemperature warning bit) is unmapped to the flt_ot open-drain output. 1 = stat. otw is mapped to flt_ot when map.otm = 1. lctm low-current threshold mapping bit. the current thresholds used in tweeter and shorted load diagnostics are lower than the current limit. when the threshold is exceeded in running either diagnostic, ostat1. load[3:0] (load indicator bit) asserts. hardware indication is also possible by using lctm to map ostat1. load[3:0] to the cl0 and mute_cl1 outputs. 0 = ostat1. load[3:0] (load indicator bit used for tweeter and shorted load diagnostics) is unmapped to the cl0 and mute_cl1 outputs. 1 = ostat1. load[3:0] is mapped to the cl0 and mute_cl1 outputs. use this setting only when running tweeter or shorted load diagnostic. mclp clip output mapping. mclp determines which open-drain outputs ( cl0 and mute_cl1 ) are used to indi - cate clipping on an audio output. cl0 is always used as a clip indicator, while mute_cl1 is configurable as a clip indicator output or as a mute input. 0 = cl0 provides clip indication for all audio outputs; mute_cl1 is configured as a mute input. 1 = cl0 provides clip indication for audio outputs 0 and 1; mute_cl1 is configured as a clip indicator out - put for audio outputs 2 and 3. otm overtemperature shutdown map 0 = stat. ot (overtemperature shutdown bit) is unmapped to the open-drain flt_ot output. 1 = stat. ot is mapped to the flt_ot output. fltm fault mapping bit 0 = faults are unmapped to the open-drain flt_ot output. 1 = any fault condition (as indicated by the status bits ov , uv , oc ) causes flt_ot to assert low.
MAX13301 4-channel, automotive class d audio amplifier 25 table_ 20._ comp[2:0]_ setting_ lookup_ table table_ 21._ status_ register table_ 22._ status_ register_ bit_ description f sw /v pvdd <_ 8v 8v_ to_ 9.5v 9.5v_ to_ 12.65v 12.65v_ to_ 15.6v 15.6v_ to_ 18.65v 18.65v_ to_ 21.1v >_ 21.1v 300k 100 100 100 011 011 010 001 320k 100 100 100 011 011 010 010 346k 100 100 100 100 011 010 010 375k 100 100 100 100 011 011 010 409k 100 100 100 100 100 011 011 450k 100 100 100 100 100 011 011 475k 100 100 100 100 100 100 011 500k 100 100 100 100 100 100 011 530k 100 100 100 100 100 100 011 562k 100 100 100 100 100 100 100 600k 100 100 100 100 100 100 100 643k 100 100 100 100 100 100 100 675k 100 100 100 100 100 100 100 700k 100 100 100 100 100 100 100 725k 100 100 100 100 100 100 100 750k 100 100 100 100 100 100 100 stat bit_ # 7 6 5 4 3 2 1 0 name ot otw ov uv oc cpuv clip bit bit_ description ot overtemperature shutdown. the device goes into thermal shutdown when the junction temperature exceeds +150 n c. 0 = device is in thermal shutdown. 1 = device is not in thermal shutdown. otw overtemperature warning. otw asserts when the junction temperature exceeds the thermal warning thresh - old programmed in ctrl0.tw[1:0]. 0 = junction temperature is greater than the programmed thermal warning threshold. 1 = junction temperature is less than the programmed thermal warning threshold. ov overvoltage indicator 0 = v pvdd is greater than the pvdd overvoltage lockout (ovlo) threshold as defined in the electrical characteristics table. 1 = v pvdd is less than the ovlo threshold. uv undervoltage indicator 0 = v pvdd is less than the pvdd undervoltage lockout (uvlo) threshold as defined in the electrical characteristics table. 1 = v pvdd is greater than the uvlo threshold.
MAX13301 4-channel, automotive class d audio amplifier 26 table_ 23._ status_ register_ 0 table_ 24._ status_ register_ 0_ bit_ description table_ 22._ status_ register_ bit_ description_ (continued) ostat0 bit_ # 7 6 5 4 3 2 1 0 name oc3 oc2 oc1 oc0 clip3 clip2 clip1 clip0 bit bit_ description oc[3:0] overcurrent indicator. an overcurrent condition such as a short-to-ground/battery on any of the outputs causes the corresponding 0em bit to latch to 0. write a 1 to this bit to clear it. reset also clears this bit. an overcurrent indicator is available for each output: oc3 is for output 3, oc2 is for output 2, etc. 0 = there is an overcurrent condition on the output. 1 = there is no overcurrent condition on the output. clip[3:0] clip indicator. 0em is a real-time clip indicator for each output. this bit asserts only during the times when an overdriven output is actually clipping. a clip indictor is available for each output: clip3 is for output 3, clip2 is for output 2, etc. 0 = output is clipping. 1 = output is not clipping. bit bit_ description oc general overcurrent indicator. oc asserts when there is an overcurrent condition on any of the outputs such as a short-to-ground/battery. to identify which output(s) is experiencing an overcurrent condition, read the ostat0. 0em (overcurrent indicator bit). 0 = an overcurrent condition exists on one or more of the outputs. 1 = no overcurrent condition. cpuv charge-pump undervoltage indicator. cpuv asserts when the voltage on the hold capacitor of the charge pump (c hold ) falls below 3.87v. it deasserts once the voltage rises above 4.1v. 0 = undervoltage on c hold 1 = adequate voltage on c hold clip general clip indicator. clip asserts when any of the outputs is clipping. to identify which output(s) is clip - ping, read the ostat0. 0em (clip indicator) bits. 0 = one or more outputs are clipping. 1 = none of the outputs are clipping.
MAX13301 4-channel, automotive class d audio amplifier 27 table_ 26._ status_ register_ 1_ bit_ description table_ 27._ status_ register_ 2 table_ 28._ status_ register_ 2_ bit_ description table_ 25._ status_ register_ 1 bit bit_ description ldok[3:0] load okay indicator. when running the open-load diagnostic, 0em = 1 if the load resistance is greater than the resistance threshold set by ctrl3.ldm (line driver mode bit), indicating that the output is properly loaded and not open. a load okay indicator is available for each output: ldok3 is for output 3, ldok2 is for output 2, etc. 0 = output is loaded. 1 = output is open. load[3:0] load indicator. when running shorted load or tweeter diagnostic, 0em asserts if there is a short across the load or if a tweeter is connected. see the shorted-load diagnostic and tweeter diagnostic sections for information on the use of 0em in performing load diagnostics. w 0em is available for each output: load3 is for output 3, load2 is for output 2, etc. 0 = load threshold exceeded. 1 = load threshold not exceeded. ostat2 bit_ # 7 6 5 4 3 2 1 0 name sbat3 sbat2 sbat1 sbat0 sgnd3 sgnd2 sgnd1 sgnd0 bit bit_ description sbat[3:0] short-to-battery indicator. when running a short-to-ground/battery diagnostic, 0em provides indica - tion of any short-to-battery for each output. use 0em to ensure that there is no short-to-battery before turning on the device. this indicator is available for each output: sbat3 is for output 3, sbat2 is for output 2, etc. 0 = output is shorted to the battery. 1 = output is not shorted to the battery. sgnd[3:0] short-to-ground indicator. when running a short-to-ground/battery diagnostic, 0em provides indi - cation of any short-to-ground for each output. use 0em to ensure that there is no short-to-ground before turning on the device. this indicator is available for each output: sgnd3 is for output 3, sgnd2 is for output 2, etc. 0 = output is shorted to ground. 1 = output is not shorted to ground. ostat1 bit_ # 7 6 5 4 3 2 1 0 name ldok3 ldok2 ldok1 ldok0 load3 load2 load1 load0
MAX13301 4-channel, automotive class d audio amplifier 28 table_ 29._ status_ register_ 3 fault detection the device integrates fault detection and protection circuitry. table 31 lists all fault events that each device can encounter, the modes in which they are detected, the method with which they are reported, the devices' response to them, and whether they cause the outputs to latch into a high-impedance state. load diagnostics the device incorporates built-in diagnostics to detect external wire harness faults that can occur during instal - lation or over time. load diagnostics include short circuit to ground or battery, shorted or open speaker, and open tweeter. load diagnostics can be run at any time when the device is in normal mode (i.e., not in standby mode) with the outputs three-stated. the presence of any of these faults is indicated by software through the status registers and by hardware through the cl0 and mute_cl1 open-drain outputs if the status bits have been mapped to the outputs. short-to-ground/battery diagnostic the diagnostic for short-to-battery and ground is done with ctrl3.sdet = 1. none of the results are latched so the ostat2 register must be read while running this diagnostic to get a valid status. if the load is present, a short on either of the differential outputs results in a short on the other output. therefore, table_ 30._ status_ register_ 3_ bit_ description table_ 31._ fault_ conditions ostat3 bit_ # 7 6 5 4 3 2 1 0 name ver vos3 vos2 vos1 vos0 bit bit_ description ver version indicator. 0 = reserved 1 = MAX13301 vos[3:0] offset voltage indicator. 0em indicates whether an offset voltage exists between the differential outputs. read this bit in play mode after precharge with no signal on the input. this bit is not latched and is not a valid indicator of offset when an input signal is present. an offset voltage indicator is available for each out - put: vos3 is for output 3, vos2 is for output 2, etc. 0 = the differential offset voltage between out_+ and out_- exceeds q 1v (typ). 1 = the differential offset voltage between out_+ and out_- is within q 1v (typ). fault monitoring_ state reporting_ method action latched overvoltage all i 2 c, flt_ot out_ to 1/2 v pvdd no undervoltage (pvdd) normal, standby i 2 c, flt_ot high-z all no charge-pump undervoltage normal i 2 c high-z all no overtemperature shutdown normal, standby i 2 c, flt_ot high-z all no overtemperature warning normal i 2 c, flt_ot none no open load normal i 2 c none no shorted load normal i 2 c high-z channel yes short-to-ground/battery normal i 2 c, flt_ot high-z channel yes clip output normal i 2 c, cl0 , mute_cl1 none no overcurrent normal i 2 c, flt_ot high-z channel yes dc offset normal, no music i 2 c none no
MAX13301 4-channel, automotive class d audio amplifier 29 the status register only indicates which channels output is shorted and not which of its differential outputs is short - ed. the i 2 c status register can indicate, for example, that output 1 is shorted to battery, but it cannot differentiate between an out1+ and out1- short-to-battery. before running the short-to-ground/battery diagnostic, perform steps 1 to 3 of the shutdown procedure out - lined in the startup and shutdown section. before set - ting ctrl3.sdet to 1, discharge the output by set - ting ctrl3.dis to 1 for 200s and reset ctrl3.dis to 0. run the short-to-ground/battery diagnostic by setting ctrl3.sdet (short-to-ground/battery diagnos - tic enable bit) to 1. to test for short-to-ground, set ctrl2.stby to 0; to test short-to-battery, set ctrl2.stby to 1. with ctrl2.stby = 0, 6v is developed at each output. an output voltage > _ 6v is interpreted as a short-to-battery. an output voltage < 150mv is inter - preted as a short to ground. results of the diagnostic are reported in the ostat2. sbat[3:0] (short-to-bat - tery indicator) and ostat2. sgnd[3:0] (short-to-ground indicator) bits. wait a minimum of 200 f s after setting ctrl3.sdet for valid results. after running the short-to- ground/battery diagnostic, clear the ctrl3.sdet bit to 0. because no latch is set, a short-to-ground or battery does not prevent the device from powering up. therefore, the microcontroller can enable the device into a short although it is discouraged. should the device be enabled into a short, the real-time overcurrent latches the shorted channel off. the device offers real-time protection for short-to-battery, short-to-ground, and shorted load to pre - vent damage to the device. open-load diagnostic this diagnostic detects an open between out_+ and out_- of > 100 i or > 300 i , depending on the value of ctrl3.ldm (line driver mode bit). before running the open-load diagnostic, perform steps 1 to 3 of the shutdown procedure outlined in the startup and shutdown section. run the open-load diagnos - tic test by setting ctrl3.rdet (open-load diagnostic enable bit) to 1, and in the same command, dis - charge the output capacitors by setting ctrl3.dis (discharge bit) to 1. during the diagnostic, all low-side fets of the negative outputs (out_-) are turned on, while all other fets are turned off. the device sources a 2ma current from out_+ to out_-. if a load is not present, out_+ swings high and is interpreted as an open output. results of the diagnostic are reported in ostat1. ldok[3:0] (load ok indicator bit). wait a minimum of 200 f s for valid results after setting ctrl3.rdet. after running the open-load diagnostic, clear ctrl3.rdet and ctrl3.dis to 0. shorted-load diagnostic this diagnostic detects shorted loads on any of the outputs. to detect shorted loads, the device should be in play mode. set ctrl3.tw (tweeter-detect current threshold setting bit) to 0 and apply a low-frequency (typically < 20hz) sinusoidal signal to all the inputs. the device compares the load current to the shorted- load current threshold. if the load current exceeds the threshold, the corresponding ostat1. load[3:0] (load indicator bit) is set to 1, indicating that there is a shorted load. the shorted-load current threshold depends on the programmed current limit as set by the ctrl3.hcl. see the high-current threshold parameter in the electrical characteristics table. note that the ostat1. load[3:0] bits do not latch high upon detecting a short. during zero crossings, the load current does not exceed the threshold and the ostat1. load[3:0] bits are cleared to 0. there are two ways to obtain the results of the shorted load diagnostic: 1) continuously read the ostat1. load[3:0] bits to determine if any have been set high. 2) the open-drain cl0 output can also be monitored if map.lctm (low-current threshold map bit) is set to 1 (setting this bit to 1 maps the ostat1. load[3:0] bits to the cl0 output). because cl0 is the nored func - tion of the ostat1. load[3:0] bits, cl0 pulls low if a short exists on any of the outputs. after running the diagnostic, clear map.lctm to 0 to unmap ostat1. load[3:0] to the cl0 output. doing so prevents cl0 from being asserted when the shorted- load current threshold is exceeded during play. shorted-load diagnostic is done on all outputs. a shorted load is traceable to the output on which it exists by examining the ostat1. load[3:0] bits. a shorted load on output 3 causes load3 to go low, a shorted load on output 2 causes load2 to go low, etc. missing speaker diagnostic using the same technique outlined above, it is possible to detect the absence of a speaker. set ctrl3.tw to 1 to decrease the shorted-load current threshold by a fac - tor of 4. apply a low-frequency sine wave (< 20hz) to the inputs and monitor the load indicator either through the i 2 c registers or the cl0 output. by using the appropriate input signal, a 2 i , 4 i , or 8 i speaker can be detected.
MAX13301 4-channel, automotive class d audio amplifier 30 tweeter diagnostic this diagnostic detects whether a tweeter is properly connected when a passive crossover is used. to detect the presence of a tweeter load, the device should be in play mode. set ctrl3.tw (tweeter-detect current threshold setting bit) to 1 and apply a 15khz to 25khz sinusoidal signal to all the inputs. the devices compare the load current to the tweeter-detect current threshold. if the load current exceeds the threshold, the correspond - ing ostat1. load[3:0] (load indicator bit) is set to 1, indicating that there is a tweeter. the amplitude of the input signal depends on the impedance vs. frequency characteristics of the tweeter. correct tweeter detec - tion requires that the amplitude be large enough to trip the tweeter-detect current threshold when a tweeter is present. the tweeter-detect current threshold depends on the programmed current limit as set by ctrl3.hcl bit. see the low-current threshold parameter in the electrical characteristics table. note that the ostat1. load[3:0] bits do not latch high upon detecting a tweeter. during zero crossings, the load current does not exceed the threshold and the ostat1. load[3:0] bits are cleared to 0. there are two ways to obtain the results of the tweeter diagnostic: 1) continuously read the ostat1. load[3:0] bits to determine if any have been set high. 2) the open-drain cl0 output can also be monitored if map.lctm (low-current threshold map bit) is set to 1 (setting this bit to 1 maps ostat1. load[3:0] to the cl0 output). because cl0 is the nored function of the ostat1. load[3:0] bits, cl0 pulls low if a short exists on any of the outputs. after running the diagnostic, clear ctrl3.tw to 0 to disable tweeter diagnostic and clear map.lctm to 0 to unmap the ostat1. load[3:0] bits to the cl0 output. doing so prevents cl0 from being asserted when the tweeter-detect current threshold is exceeded during play. tweeter diagnostic is done on all outputs. the presence of a tweeter is traceable to any output by examining the ostat1. load[3:0] bits. the presence of a tweeter on output 3 causes load3 to go high, the presence of a tweeter on output 2 causes load2 to go high, etc. continuous diagnostics the device constantly monitors critical performance and safety parameters such as output offset voltages, output clipping, thermal faults, and undervoltage and overvoltage conditions. the results are reported and continuously updated in the status registers (stat and ostat[3:0]). offset diagnostic run the offset diagnostic to determine if there is an offset between the differential outputs. to do so, place the device in play mode and apply no input signals. the results of this diagnostic are reported in ostat3. vos[3:0] (offset voltage indicator bits). ostat3. vos[3:0] indicates whether the offset voltage is less than or greater than the offset voltage threshold. the differential offset threshold is q 1v (typ) for the MAX13301. clipping diagnostic use the clipping diagnostic to detect clipping outputs. program ctrl1.clvl[1:0] (clip level bit) for a threshold of either 1%, 3%, 5%, or 10% thd+n. clip indication is provided by ostat0. clip[3:0] (clip indicator bit). these bits are set to 0 only during the times when an overdriven output is actually clipping. a clipping output indicator is available for each output: clip3 is for output 3, clip2 is for output 2, etc. the open-drain outputs, cl0 and mute_cl1 , also provide clip indication. thermal warning diagnostic and thermal shutdown if the junction temperature exceeds the programmed temperature limit, then a temperature warning is set immediately (i.e., stat. otw goes low). the device does not act upon a temperature fault to the programmed limit. the temperature fault self clears when the temperature drops below the threshold. the programmed tem - perature limit is set by ctrl0.tw[1:0] (thermal warning threshold bits) from +110 n c to +140 n c in 10 n c incre - ments. overtemperature warning by the hardware is also possible by setting both the map.otwm (overtem - perature warning map) and map.otm (overtemperature shutdown mask) to 1 to map the stat. otw (overtem - perature warning) bit to the flt_ot output. if the junction temperature exceeds +150 n c, the device disables all channels and the stat. ot (overtemperature shutdown) bit asserts low. the digital interface remains active and the contents of the registers are unchanged. when the die temperature drops below +140 n c, normal operation is restored. thermal shutdown indication by hardware is also possible by setting map.otm (over - temperature shutdown map bit) to 1 to map the stat. ot (overtemperature shutdown bit) to the flt_ot output. charge-pump undervoltage diagnostic the device drives the high-side fets with the aid of a charge pump. the charge pump charges the hold capacitor c hold to 5v at the end of each switching cycle. when the voltage on c hold falls below 3.87v, the devices assert stat. cpuv (charge-pump under - voltage indicator bit) and three-state all outputs. the
MAX13301 4-channel, automotive class d audio amplifier 31 device deasserts the bit only after the voltage on the hold capacitor rises above 4.1v. undervoltage diagnostic an undervoltage monitor detects low voltages on pvdd (< 6v). during an undervoltage condition, the devices three-state all outputs, set the stat. uv (undervoltage indicator) bit to 0, and assert the open-drain output flt_ot . overvoltage diagnostic the device detects overvoltage and load-dump condi - tions on pvdd and protect the dmos outputs from damage. during an overvoltage condition, the devices set stat. ov (overvoltage indicator bit) to 0, assert the open-drain output flt_ot , and are latched into standby mode. all differential outputs are regulated to 1/2 v pvdd to minimize the drain-source voltage of the low- and high-side fets. once the overvoltage condi - tion is removed, bring the devices out of standby mode by clearing ctrl2.stby (standby bit). the device can withstand 50v load-dump voltage spikes. battery char - ger voltages from 26v to 35v can be withstood for up to 1 hour. figure 7 illustrates the behavior of the device during a load dump. fault indication faults discovered during load diagnostic and continuous diagnostic are indicated through software and hardware. the appropriate status indicator bits (found in the stat and ostat[3:0] registers) assert upon detection of a fault. the host is made aware of the fault through the fault indicator outputs cl0 , mute_cl1 , and flt_ot . the host then reads the appropriate status registers to determine which specific fault has occurred. cl0 , mute_cl1 cl0 is an open-drain output that indicates clipping on the audio outputs. mute_cl1 can be configured as an open-drain output that also indicates clipping on the audio outputs. cl0 also finds use in shorted load and tweeter diagnostics. flt_ot the device asserts the flt_ot open-drain output upon detecting a fault. a fault is any of the following events: overvoltage, undervoltage, temperature exceeds the programmed overtemperature warning threshold, over - temperature shutdown, and overcurrent. figure 7. behavior during load dump 200ms max max ramp rate 25v/ms overvoltage protection up to 50v standby mode high-z all channels v pvdd 50v 28.8v 26v 14.4v operating range 6v to 25.5v ready to exit standby mode time
MAX13301 4-channel, automotive class d audio amplifier 32 fault mapping the map register contains the compensation capacitor, clip output mapping, overtemperature mapping, low- current threshold mapping, and fault mapping bits. the map.comp[2:0] bits set the internal inte - grator and triangle-wave capacitor. the value of map.mclp (clip output mapping bit) determines whether mute_cl1 is a mute input or clip indicator output. map.otwm and map.otm map the overtemperature warning bit stat. otw and overtemperature shutdown bit stat. ot to the flt_ot output. map.lctm enables the low-current threshold mapping when running tweeter and shorted load diagnositics. the fault map is enabled by setting map.fltm to 1, this maps the status register bits stat. ov , stat. uv , and stat. oc to the flt_ot output. applications information startup and shutdown follow these procedures for starting up and shutting down the device. for startup: 1) set the state of mute_cl1 to select the i 2 c slave address (see table 2). 2) pull the enable input en high. 3) release mute_cl1 . 4) if more than two i 2 c addresses are needed, then write to ctrl4.addr[1:0] to set the new address. the new address can be set to one of the four addresses shown in table 3. 5) write ctrl5.addr_def = 0 to enable the new address, if more than two i 2 c addresses are needed. 6) set ctrl0, ctrl1.clvl[1:0], ctrl1.cm[1:0], ctrl3.hcl, ctrl3.ldm, ctrl4, and ctrl5 to the desired values based on application requirements. 7) set ctrl1.cl_th = 1. 8) set ctrl2.stby = 0 to enable the device. 9) wait 50ms for the charge pump and reference to stabilize. 10) set ctrl2.md23_[1:0] = ctrl2.md01_[1:0] = 01 to mute the outputs. delay at least 50 f s before proceed - ing. 11) wait 200 f s and then clear ctrl1.cl_th back to 0. 12) set ctrl2.md23_[1:0] = ctrl2.md01_[1:0] = 11 to set the outputs to play mode. for shutdown: 1) set ctrl2.md23_[1:0] = ctrl2.md01_[1:0] = 01 to mute the outputs. 2) wait at least 25ms to ensure that there is no click-and- pop noise from a 20hz signal. 3) set ctrl2.md23_[1:0] = ctrl2.md01_[1:0] = 00 to three-state the output. 4) set ctrl2.stby = 1 to go into standby mode. 5) pull the enable input en low. before running open-load diagnostic or short-to-ground/ battery diagnostic, follow steps 1 to 3 of the shutdown procedure to prevent click-and-pop noise. class d operation class d amplifiers differ from analog amplifiers such as class ab in that their output waveform is composed of high-frequency pulses from ground to the supply rail. when viewed with an oscilloscope, the audio signal is not seen; instead, the high-frequency pulses dominate. to evaluate the output of a class d amplifier requires taking the difference from the positive and negative out - puts, then lowpass filtering the difference to recover the amplified audio signal. gain the gain for all 4 channels on the device is fixed at 26db. output configuration the device offers flexible output configurations for either 4-channel, 2.1 or high-power, 2-channel sound systems. the configurations are selected using ctrl5.par[1:0] (parallel mode bit). in a 2.1 configura - tion, either outputs 0 and 1 are paralleled together and slaved to input 0, or outputs 2 and 3 are paralleled together and slaved to input 2. in a high-power, 2-chan - nel configuration, outputs 0 and 1 are paralleled and slaved to input 0, while outputs 2 and 3 are paralleled and slaved to input 2. see the control register 5 bit description table (table 16) for more information about programming the desired output configuration. feedback connect the speaker inputs to the feedback inputs through 150 i q 1% resistors as shown in the typical operating circuit . integrated feedback from the lc fil - ters output improves the thd+n by reducing distortion.
MAX13301 4-channel, automotive class d audio amplifier 33 external filters the class d amplifiers work with external filters. the filter requirement is due to the unshielded wiring harness. this is common for longer speaker lead lengths, and to gain increased margin to emc limits. see figure 8 for the cor - rect connections of these components. the component selection is based on the load imped - ance of the speaker. table 32 lists suggested values for a variety of load impedances. inductors l1 and l2 and capacitor c2 form the primary output filter. in addition to these primary filter components, other components in the filter improve its functionality. rc networks r1-c4 and r2-c5 form zobels at the output. a zobel corrects the output loading to compensate for the rising impedance of the loudspeaker. without a zobel, the filter has a peak in its response near the cutoff frequency. capacitors c1 and c3 provide additional high-frequency bypass to reduce radiated emissions. power supplies the devices use different supplies for each portion of the device, allowing for the optimum combination of headroom, power dissipation, and noise immunity. the speaker amplifiers are powered from pvdd and can range from 6v to 25.5v. the remainder of the device is powered by v dd (analog and digital blocks) and v dd5 (gate drivers and charge-pump circuit). power supplies are independent of each other so sequencing is not necessary. power can be supplied by separate sources or derived from a single higher source using a linear regulator to reduce the voltage, as shown in figure 9. component selection input filter the device has four positive inputs and one common negative input. the input resistance of each positive input is 20k i , while the input resistance of the negative input is 5k i . an input capacitor, c in , in conjunction with the input resistance forms a highpass filter that removes the dc bias from an incoming signal. the dc-blocking capacitor allows the amplifier to automati - cally bias the signal to an optimum dc level. assuming zero-source impedance, the -3db point of the highpass filter is given by: f 0 = 1/2 g r in c in figure 8. output filter figure 9. using a linear regulator to produce 5v from a 24v power supply table_ 32._ suggested_ values_ for_ lc_ filters * parallel channel operation: at 14.4v (for r l = 1 i ), at 24v (for r l = 2 i ). MAX13301 out_+ out_- l1 l2 c5 r1 r2 rl c1 c4 c3 c2 shdn gnd in pvdd 5v 2i 0.1f v dd5 24v v dd 1f 4.7f out max16910 MAX13301 22f gnd pgnd r l _ ( i ) l1,_ l2_ (h) c1,_ c3_ (f) c2_ (f) c4,_ c5_ (nf) r1,_ r2_ ( i ) 8 10 0.15 0.47 220 10 4 10 0.15 0.47 220 10 2* 10 0.15 0.68 220 10 1* 10 0.15 1 220 10
MAX13301 4-channel, automotive class d audio amplifier 34 charge-pump capacitor selection use capacitors with an esr less than 100m i 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. the typical value is 1 f f. flying capacitor (c fly ) the value of the flying capacitor (c fly ) affects the load regulation and output resistance of the charge pump. a c fly value that is too small degrades the devices ability to provide sufficient current drive. increasing the value of c fly improves load regulation and reduces the charge- pump output resistance to an extent. use a 50v, 1 f f ceramic capacitor for c fly . supply bypassing, layout, and grounding proper layout and grounding are essential for optimum performance. use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. large traces also aid in moving heat away from the package. proper ground - ing improves audio performance, minimizes crosstalk between channels, and prevents any switching noise from coupling into the audio signal. connect pgnd and gnd together at a single point on the pcb. route all traces that carry switching transients away from gnd and the traces/components in the audio signal path. bypass v dd to gnd with a 10 f f ceramic capacitor and v dd5 to pgnd with a 0.1 f f ceramic capacitor. each pvdd is paired with two pgnds for local supply bypassing. bypass each pvdd-pgnd pair with 0.1 f f and 4.7 f f ceramic capacitors. table 35 shows the four pvdd-pgnd pairs. place an additional 1000 f f low-esr electrolytic capaci - tor from pins 1 and 48 to pgnd and from pins 24 and 25 to pgnd. use large, low-resistance output traces. current drawn from the outputs increases as load impedance decreas - es. high output trace resistance decreases the power delivered to the load. large output, supply, and pgnd traces allow more heat to move from the device to the air, decreasing the thermal impedance of the circuit. the feedback connections are sensitive to inductor mag - netic field interference, so route these traces away from the inductors and noisy traces connected to out_ and the charge pump. refer to the MAX13301 evaluation kit for a pcb layout example. thermal information the device requires external heatsinking for applica - tions that dissipate more than 1333.3mw. the top side exposed pad is the primary heat conduction path on the device. the thermal resistance of the heatsink is calcu - lated from the following equation: j a hs jc ch diss t - t p ? ? ? ? ? ? ? ? where: t j = +150c t a = ambient operating temperature b jc = 1c/w b ch = thermal resistance of the thermal interface used between the top side exposed pad and the heatsink p diss = estimated power dissipation of the device the estimated power dissipation can be calculated from the following equation based on the desired continuous output power, p out , of the application, the typical effi - ciency, e , and the number of output channels used, n. diss out 1 p 1 n p ? ? ? ? ? ? ? table_ 33._ pvdd_ and_ pgnd_ pairs pvdd_ pin_ number pgnd_ pin_ number 1 9 and 10 48 39 and 40 24 11 and 12 25 37 and 38
MAX13301 4-channel, automotive class d audio amplifier 35 typical operating circuit 1f 1f 4 x 0.47f 4.7f single- ended analog audio inputs out0+ out0- 2i fb0+ fb0- cp pgnd pgnd pgnd pgnd pvdd pvdd pgnd 1nf 10h 10h pgnd pgnd pgnd pvdd pvdd chold cm in0+ in1+ in2+ in3+ in- ref 2.0f 0.1f 10f 5v supply 5v supply 2.2f v l i/o control and status v l v l v l clo flt_ot mute_cl1 en sync scl v dd5 pgnd 1.5ki 1.5ki sda MAX13301 4.7f v bat 0.1f 1000f 4.7f 4.7f v bat 0.1f 1000f v dd gnd 2i 1nf 0.68f 150nf 150nf 0.22f 0.22f 10i 150i, 1% 10i 150i, 1% out1+ out1- 2i fb1+ fb1- 1nf 10h 10h 2i 1nf 0.68f 150nf 150nf 0.22f 0.22f 10i 150i, 1% 10i 150i, 1% out2+ out2- 2i fb2+ fb2- 1nf 10h 10h 2i 1nf 0.68f 150nf 150nf 0.22f 0.22f 10i 150i, 1% 10i 150i, 1% out3+ out3- 2i fb3+ fb3- 1nf 10h 10h 2i 1nf 0.68f 150nf 150nf 0.22f 0.22f 10i 150i, 1% 10i 150i, 1%
MAX13301 4-channel, automotive class d audio amplifier 36 chip information process: bicmos 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. package_ type package_ code outline_ no. land_ pattern_ no. 48 tssop-epr u48er+1 21-0444 90-0273
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit 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 37 ? 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. MAX13301 4-channel, automotive class d audio amplifier revision history revision number revision date description pages changed 0 6/11 initial release

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