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max16929 automotive tft-lcd power supply with boost coverter te olte eultors ????????????????????????????????????????????????????????????????? maxim integrated products 1 general description the max16929 is a highly integrated power supply for automotive tft-l appliations the devie integrates one u onverter one oost onverter one 1 regulator ontroller and two gate voltage regulators the devie omes in several versions to satisfy om- mon automotive power-supply reuirements see the ordering information/selector guide tale esigned to operate from a single to 2 supply or to 2 supply the devie is ideal for automotive tft-l appliations oth the u and oost onverters use spread-spe- trum modulation to redue pea interferene and to opti- mie m performane the seuening input allows fleile seuening of the positive-gate and negative-gate voltage regulators the power-good indiator indiates a failure on any of the onverters or regulator outputs ntegrated thermal shutdown iruitry protets the devie from over- heating the max16929 is availale in a 2-pin t pa- age with eposed pad and operates over the - n to 1 n temperature range applications automotive ashoards automotive entral nformation isplays automotive avigation ystems features s operating voltage range of 4v to 28v (buck) or 3v to 5.5v (boost) s inepenent 28v input buck onerter oers bias uppl ircuitr an ternal ircuitr s igoer (p to ) boost output roiing p to 18v s 1.8v or 3.3v regulator roies 5 it ternal npn ransistor s one ositieate voltage regulator apale of eliering 2 at 28v s one egatieate voltage regulator s igreuenc operation ? 2.1 (buck onerter) ? 2.2 (boost onerter) s leile tanlone euencing s rue uton? boost onerter s ourrent uton oe (buck) s internal ofttart s oerteperature uton s 4 n to 15 n operation 19-5857; rev 2; 1/12 true sutdon i a trademar of aim integrated roduct inc typical application circuit appears at end of data sheet. ordering information/selector guide appears at end of data sheet. or related art and recommended roduct to ue it ti art refer to .maximic.com/ma.related a l a t t a a l a b l or pricing elier an orering inforation please contact ai irect at 18882442 or isit ais esite at .aiic.co. downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products 2 max16929 automotive tft-lcd power supply with boost coverter te olte eultors to - to 2 t to - to t to lx - to 6 lx to -6 to 2 al to - to 6 f to - to 12 to - to 1 to a - to 29 lx to - to 2 to -2 to a m f to - to 6 f at m f fl f to - to a to - to ontinuous ower issipation t a n t derate 2m n aove n 2162m perating temperature ange - n to 1 n untion temperature ange - n to 1 n torage temperature ange -6 n to 1 n lead temperature soldering 1s n oldering temperature reflow 26 n t untion-to-amient thermal esistane b a n untion-to-ase thermal esistane b 2 n bo i ri ote 1 aage thermal resistanes were otained using the method desried in speifiation 1- using a four- layer oard for detailed information on paage thermal onsiderations refer to .aiic.coteraltutorial stree eond toe lited under olute aimu m rating ma caue ermanent damage to te device tee are tre rating onl and functional oe ra- tion of te device at tee or an oter condition eond toe indicated in te oerational ection of te ecification i not imlied oure to aolute maimum rating condition for etended eriod ma affect device reliailit r rrii (ote 1) ri rrii 12 a t a t - n to 1 n typial values are at t a 2 n unless otherwise noted ote 2 rr bo oiio i i b ovrr upply oltage ange t ote 2 t ote 2 t ms 2 upply urrent 6 9 f a no load t a 2 n ndervoltage loout l al rising 1 ndervoltage loout ysteresis m withing freueny f 19 21 2 m pread-petrum ange 6 utput-oltage auray t 6 p p 1 la full load ontinuous mode - sip mode - 6 ontinuous mode - sip mode - 6 igh-ide m lx lx 1a 1 m i ip-urrent threshold 16 max urrent-limit threshold max t 12a option 16 2 2 a t 2a option 2 downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products 3 max16929 automotive tft-lcd power supply with boost coverter te olte eultors ri rrii (continue) 12 a t a t - n to 1 n typial values are at t a 2 n unless otherwise noted ote 2 rr bo oiio i i oft-tart amp time 9 ms maimum uty yle ontinuous mode minimum uty yle ontinuous mode 2 maimum uty yle in ropout ropout 9 thermal hutdown temperature 1 n thermal hutdown ysteresis 1 n or oo (oo) threshold ising 9 falling 9 92 9 eoune time 1 f s utput igh-leaage urrent 2 f a utput low level oi v threshold rising 1 1 22 ysteresis 2 nput urrent 9 f a boo oiiv () iv () 1.8v3.3v ovrr a nput upply ange a a upply urrent a f f 1 fl lx not swithing 1 2 ma a ndervoltage loout threshold al a rising hysteresis 2m t a 2 n 2 2 29 a hutdown urrent t a 2 n f a thermal hutdown temperature t temperature rising 16 n thermal hutdown ysteresis t 1 n uration to trigger fault ondition f f or fl elow its thresh- old 2 ms autoretry time 19 s rr (r) f utput oltage f o output urrent 126 12 126 f load egulation f f a f souring -2 2 f ndervoltage loout threshold ising edge hysteresis 2m 116 oior nternal sillator freueny f t a 2 n 96 m pread-petrum modulation freueny f f 2 m downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products 4 max16929 automotive tft-lcd power supply with boost coverter te olte eultors ri rrii (continue) 12 a t a t - n to 1 n typial values are at t a 2 n unless otherwise noted ote 2 rr bo oiio i i pread-petrum fator as a perentage of swithing freueny f q boo ovrr withing freueny f 19 22 22 m maimum uty yle 2 9 lx urrent limit lm uty yle m 22pf low oost urrent- limit option 62 a igh oost urrent- limit option 12 16 1 lx n-esistane lx lx 2ma 11 2 m i lx leaage urrent llx lx 2 t a 2 n 2 f a oft-tart time ote ms utput oltage ange a 1 f egulation oltage f a to la full load t a 2 n 9 1 11 t a - n to 1 n 9 1 12 threshold f measured at f 96 f load egulation la full load -1 f line egulation a to 1 f nput ias urrent f 1 t a 2 n q 1 f a f to m transondutane d q 2 f a at m t a 2 n f oiiv vo ror () utput oltage ange ith eternal harge pump t a 2 n maimum 29 29 vervoltage threshold t a 2 n ote 6 29 f egulation oltage f 1ma 9 1 1 threshold f measured at f f load egulation to 2ma 2 f line egulation 12 to 2 at 1 1ma 2 f nput ias urrent f 1 t a 2 n q 1 f a utput urrent - 2 2 ma urrent limit lm 6 ma oft-tart time ms iv vo ror () utput oltage ange -2 -2 fl egulation oltage fl 1 f a 212 22 21 downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products 5 max16929 automotive tft-lcd power supply with boost coverter te olte eultors ri rrii (continue) 12 a t a t - n to 1 n typial values are at t a 2 n unless otherwise noted ote 2 ote 2 peifiations over temperature are guaranteed y design and not prodution tested ote 3 peration in light-load onditions or at etreme duty yles result in sipped yles resulting in lower operating freueny and possily limited output auray and load response ote 4 of the soft-start voltage time is due to the s oft-start ramp and the other is due to the set tling of the output voltage ote 5 uaranteed y design not prodution tested ote after the voltage at eeeds this overvoltage threshold the entire iruit swithes off and autoretry is started ote f power good is indiated y the ondition f f does not shutdownrestart the devie rr bo oiio i i threshold fl measured at fl 2 fl nput ias urrent fl 2 q 1 f a oure urrent fl -1 2 ma oure urrent limit 2 ma l oft-tart time ms 1.8v3.3v ror oror utput oltage f f regulator option 1 1 regulator option 16 1 1 f threshold f measured at f otes regulator option f rising 2 2 2 1 regulator option 16 1 196 f nput ias urrent f 1 2 f a f rive urrent f 1 6 ma i ri i oro p-hannel ft at in urrent at f a at oltage threshold measured at at elow this voltage the eternal p-hannel ft is onsidered on 12 ii oi nput ulldown esistor alue i nput-oltage low l a nput-oltage igh a leaage urrent l t a 2 n q 1 f a utput-oltage low l 2ma sin urrent t a 2 n downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products max16929 automotive tft-lcd power supply with boost coverter te olte eultors typical operating characteristics a 12 measurements taen on a version unless otherwise noted 12 1 l -6 t t a 2 n unless otherwise noted load-transient response (buck) max16929 toc06 i outb 1a/div 1.8a0.2a v outb (ac-coupled100v/div 00/div startup waveforms (buck) max16929 toc05 v enb 5v/divi lxb 2a/div v outb 2v/div 1ms/div load regulation (buck) max16929 toc04 load current (a) error (%) 1.6 1.2 0.8 0.4 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 -6 0 2.0 v inb = 28v v inb = 18v v inb = 12v line regulation (buck) max16929 toc03 input voltage (v) error (%) 26 24 20 22 8 10 12 14 16 18 6 -3.2 -2.4 -1.6 -0.8 0 0.8 1.6 2.4 3.2 4.0 -4.0 4 28 i outb = 0a i outb = 1a i outb = 2a efficiency vs. load current (buck) max16929 toc02 load current (a) 1.6 1.2 0.8 0.4 0 2.0 efficiency (%) 10 20 30 40 0 60 0 80 90 100 0 in 12 in 18 in 28 shutdown supply current (buck) max16929 toc01 supply voltage (v) supply current (a) 24 20 16 12 8 2 4 6 8 10 12 14 16 18 20 0 4 28 downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products max16929 automotive tft-lcd power supply with boost coverter te olte eultors typical operating characteristics (continued) a 12 measurements taen on a version unless otherwise noted 12 1 l -6 t t a 2 n unless otherwise noted line regulation (boost) max16929 toc13 error (%) -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 input voltage (v) .0 4. 4.0 3. 3.0 . i loa 0a load regulation (boost) max16929 toc12 load current (ma) 400 300 200 100 0 500 error (%) -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 na 3.3 na 5 efficiency vs. load current (boost) max16929 toc11 load current (ma) 400 300 200 100 0 500 efficiency (%) 10 20 30 40 50 60 0 0 90 100 0 ina 33 ina 5 ina shutdown supply current max16929 toc10 input voltage (v) 5.0 4.5 4.0 3.5 3.0 5.5 supply cuent (a) 1 2 3 4 5 6 9 10 0 load dump response max16929 toc09 v inb 20v/divi lxb 2a/div v outb 5v/div 100ms/div 42v12v short-circuit behavior (buck) max16929 toc08 v outb 5v/divi lxb 2a/div v pgood 5v/div 100ms/div line-transient response (buck) max16929 toc07 v inb 10v/div 28v12v v outb (ac-couple0v/div 1/div downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products 8 max16929 automotive tft-lcd power supply with boost coverter te olte eultors typical operating characteristics (continued) a 12 measurements taen on a version unless otherwise noted 12 1 l -6 t t a 2 n unless otherwise noted line regulation (gh regulator) max16929 toc19 v cp voltage (v) error (%) 29 28 26 27 20 21 22 23 24 25 19 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 18 30 loa 10a loa 20a load regulation (gh regulator) max16929 toc18 load current (ma) error (%) 18 16 12 14 4 6 8 10 2 -3.6 -3.2 -2.6 -2.4 -2.0 -1.6 -1.2 -0.8 -0.4 0 -4.0 0 20 supply sequencing waveforms (v seq = v ina ) max16929 toc17 v enp 5v/divv sh 5v/div v gh 5v/divv gl 5v/div v reg 5v/div 10ms/div supply sequencing waveforms (v seq = 0v) max16929 toc16 v enp 5v/divv sh 5v/div v gh 5v/divv gl 5v/div v reg 5v/div 10ms/div load-transient response (boost) max16929 toc15 i sh 500ma/div v sh 100mv/div 100s/div 450ma 50ma startup waveforms (boost) max16929 toc14 v enp 5v/divv lxp 10v/divv sh 10v/div i lxp 1a/div 4ms/div downloaded from: http:///
????????????????????????????????????????????????????????????????? maxim integrated products max16929 automotive tft-lcd power supply with boost coverter te olte eultors typical operating characteristics (continued) a 12 measurements taen on a version unless otherwise noted 12 1 l -6 t t a 2 n unless otherwise noted load-transient response (3.3v linear regulator) max16929 toc23 i outb 500ma/div v reg (ac-coue100mv/div 100/div 50ma 50ma load regulation (3.3v linear regulator) max16929 toc22 load current (ma) error (%) 450 400 300 350 100 150 200 250 50 -0.18 -0.16 -0.14 -0.12 -0.10 -0.08 -0.06 -0.04 -0.02 0 -0.20 0 500 line regulation (gl regulator) max16929 toc21 v cn voltage (v) error (%) -8 -10 -14 -12 -20 -18 -16 -22 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 -24 -6 i load = 20ma i load = 10ma load regulation (gl regulator) max16929 toc20 load current (ma) error (%) 18 16 12 14 4 6 8 10 2 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 0 0 20 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 1 max16929 automotive tft-lcd power supply with boost coverter te olte eultors pin configuration pin description i io 1 oost iruitry and 1 egulator ontroller nale nput has an internal i pulldown resistor rive high for normal operation and drive low to plae the devie eept u onverter in shutdown 2 1 or egulator utput has a ma min drive apaility for greater output urrent apa- ility use an eternal npn ipolar transistor whose ase is onneted to f 1 or egulator feeda nput f is regulated to 1 or onnet f to when power- ing loads demanding less than ma for greater output urrent apaility use an eternal npn ipo- lar transistor whose emitter is onneted to f at ternal p-hannel ft ate rive at is an open-drain driver onneted to the gate of the eternal input series p-hannel ft onnet a pullup resistor etween at and a uring a fault ondition the gate driver turns off and the pullup resistor turns off the ft oost onverter ower round 6 lx oost onverter withing ode onnet lx to the indutor and ath diode of the oost onverter a oost iruitry and 1 egulator ontroller ower nput onnet a to a to supply m oost rror amplifier ompensation onnetion onnet a ompensation networ etween m to 9 f oost onverter feeda nput f is regulated to 1 onnet f to the enter of a resistive divid- er onneted etween the oost output and + top view tssop 25 4 fbgh gate 26 3 fbgl fb 27 2 ref dr 28 1 seq enp 22 7 drvn ina 23 6 gnd lxp 21 8 gh compv 20 cp fbp 1 10 pgood fbb 18 11 gnd avl 17 12 enb bst 16 13 inb lxb 24 5 compi pgndp 15 14 inb lxb ep max16929 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 11 max16929 automotive tft-lcd power supply with boost coverter te olte eultors pin description (continued) i io 1 f u onverter feeda nput f is regulated to either or onnet f to the output-volt- age node t as shown in the tical lication ircuit 11 al u onverter nternal egulator onnet a 1 f f apaitor etween al and the analog ground plane o not use al to power eternal iruitry 12 t u onverter ootstrap apaitor onnetion onnet a 1 f f apaitor etween t and lx 1 1 lx u onverter ndutor onnetion onnet the indutor oost apaitor and ath diode at this node 1 16 u onverter ower nput onnet to a to 2 supply onnet a 1 f f or larger erami apai- tor in parallel with a f f ul apaitor from to the power ground plane onnet oth power inputs together 1 u onverter nale nput is a high-voltage ompatile input onnet to for normal opera- tion and onnet to ground to disale the u onverter 1 2 analog round 19 pen-rain ower-ood utput onnet to a through an eternal pullup resistor 2 ositive-ate oltage egulator ower nput onnet to the positive output of the eternal harge pump nsure that does not eeed the overvoltage threshold as given in the lectrical aracteritic tale 21 ositive-ate oltage egulator utput 22 egative-ate oltage egulator river utput is the open drain of an internal p-hannel ft onnet to the ase of an eternal npn pass transistor 2 m oost lope ompensation onnetion onnet a apaitor etween m and to set the slope ompensation 2 f ositive-ate oltage egulator feeda nput f is regulated to 1 onnet f to the enter of a resistive divider onneted etween and 26 fl egative-ate oltage egulator feeda nput fl is regulated to 2 onnet fl to the enter of a resistive divider onneted etween f and the output of the negative-gate voltage regulator 2 f 12 eferene utput ypass f to with a 1 f f erami apaitor 2 euening nput has an internal i pulldown resistor determines the seuene in whih and l power-up ee tale 1 for supply seuening options posed ad onnet to a large ontiguous opper ground plane for optimal heat dissipation o not use as the only eletrial ground onnetion downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 12 max16929 automotive tft-lcd power supply with boost coverter te olte eultors detailed description the max16929 is a highly integrated power supply for automotive tft-l appliations the devie integrates one u onverter one oost onverter one 1 regulator ontroller one positive-gate voltage regulator and one negative-gate voltage regulator the devie ahieves enhaned m performane through spread-spetrum modulation igital input ontrol allows the devie to e plaed in a low-urrent shutdown mode and provides fleile seuening of the gate voltage regulators nternal thermal shutdown iruitry protets the devie from overheating the u onverter is designed to shut down when its die temperature reahes 1 n typ while the oost iruitry does so at 16 n typ ah resumes normal operation one its die temperature has fallen 1 n elow its respetive thermal shutdown temperature the devie is fatory-trimmed to provide a variety of power options to meet the most ommon automotive tft-l display power reuirements as outlined in the ordering information/selector guide tale buck converter the devie features a urrent-mode u onverter with an integrated high-side ft whih reuires no eternal ompensation networ the u onverter regulates the output voltage to within q in ontinuous mode over line and load onditions the high 21m typ swithing freueny allows for small eternal omponents redued output ripple and guarantees no am interferene a power-good indiator is availale to moni- tor output-voltage uality the enale input allows the devie to e plaed in shutdown reduing supply ur- rent to f a the u onverter omes with a preset output voltage of either or and an deliver either 12a or 2a to the output nale onnet to for always-on operation is also ompatile with logi systems and an e on- trolled through a miroontroller or y automotive or a inhiit signals internal egulator a al is an internal regulator that supplies power to the u ontroller and harges the oost apaitor after enaling the u onverter al egins to rise ne al eeeds the undervoltage loout voltage of ma lx starts swithing ypass al to with a 1 f f erami apaitor spreadspectrum modulation the u onverter features spread-spetrum operation that varies the internal operating freueny of the u onverter y 6 relative to the swithing freueny of 21m typ softstart the u onverter features an internal soft-start timer the output voltage taes 9ms to ramp up to its set voltage f a short iruit or undervoltage is enountered after the soft-start timer has epired the devie enters hiup mode during whih soft-start is reattempted every 16ms this proess repeats until the short iruit has een removed overcurrent protection the devie enters hiup mode in one of three ways f eight onseutive urrent limits are deteted and the out- put is elow of its nominal value the u onverter enters hiup mode the onverter enters hiup mode immediately if the output is short iruited to ground output elow 1 additionally the devie enters hiup mode if 26 onseutive overurrent events are deteted when the output is greater than of its nominal value n hiup mode the u ontroller idles for 16ms efore reattempting soft-start poer good (pgood) hen an overurrent ondition auses the u output to fall elow 92 of its set voltage the open-drain power- good indiator output asserts low deasserts one the output voltage has risen aove 9 of its set voltage serves as a general fault indiator for all the onverters and regulators esides indiating an under- voltage on the u output it also indiates any of the faults listed in the ault ondition and goo setion boost converter the oost onverter employs a urrent-mode fied- freueny m arhiteture to maimie loop andwid th and provide fast transient response to pulsed loads typial of tft-l panel soure drivers the 22m swithi ng freueny allows the use of low-profile indutors a nd erami apaitors to minimie the thiness of l panel designs the integrated low on-resistane mft and downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 13 max16929 automotive tft-lcd power supply with boost coverter te olte eultors the devies uilt-in digital soft-start funtions redue the numer of eternal omponents reuired while ontrol- ling inrush urrents the output voltage an e set from a to 1 with an eternal resistive voltage-divider the regulator ontrols the output voltage y modulat- ing the duty yle of the internal power mft in eah swithing yle the duty yle of the mft is approimated y 1 ? where is the voltage at a the oost output voltage and e is the effiieny of the oost on- verter as shown in the tical oerating aracteritic figure 1 shows the funtional diagram of the oost regulator an error amplifier ompares the signal at f to 1 and hanges the m output the voltage at m sets the pea indutor urrent as the load var- ies the error amplifier soures or sins urrent to the m output aordingly to produe the pea indu- tor urrent neessary to servie the load to maintain staility at high duty yles a slope-ompensation sig- nal set y the apaitor at m is summed with the urrent-sense signal n the rising edge of the internal lo the ontroller turns on the n-hannel mft and applies the input voltage aross the indutor the urrent through the indutor ramps up linearly storing energy in its magneti field ne the sum of the urrent feeda signal and the slope ompensation eeeds the m voltage the ontroller turns off the mft the indutor urrent then flows through the diode to the output the mft remains off for the rest of the lo yle igure 1 oot onverter unctional iagram logic and driver lxp clock pgndp v limit fbp compicompv error amp 1v 0.85v fault comparator to fault logic 2.2mhz oscillator pwm comparator i lim comparator soft- start current sense slope comp max16929 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 14 max16929 automotive tft-lcd power supply with boost coverter te olte eultors the eternal p-hannel ft ontrolled y at protets the output during fault onditions and provides true hutdown of the onverter onnet a pullup resistor etween at and a see the oot onverter setion to selet the value for the pullup resistor nder normal operation at turns on the p-hannel ft onneting the supply to the oost input uring a fault ondition or in shutdown at is off and the pullup resistor turns off the p-hannel ft disonneting the supply from the oost input spreadspectrum modulation the high-freueny 22m operation of the oost on- verter eeps swithing noise outside of the am and the devie ahieves enhaned m performane y modu- lating the swithing freueny y q the modulating signal is pseudorandom and hanges eah swithing period ie f 22m startup mmediately after power-up oming out of shutdown or going into autoretry the oost onverter performs a short-iruit detetion test on the output y onneting the input a to the swithing node lx through an internal i resistor f the resulting voltage on lx eeeds 12 the devie turns on the eternal pm swith y pulling at low the oost output ramps to its final value in 1ms an overloaded or shorted output is deteted if the result- ing voltage on lx is elow 12 the eternal pm swith remains off and the onverter does not swith after the fault laning period of 2ms the devie pulls low and starts the autoretry timer the short-iruit detetion feature plaes a lower limit on the output load of approimately 6 i when the input voltage is ault conditions and pgoo signals whether all the regulators and the oost onverter are operating normally is an open- drain output that pulls low if any of the following faults our 1 the oost output voltage falls elow of its set value 2 the positive-gate voltage regulator output falls elow of its set value the negative-gate voltage regulator output l falls elow of its set value the lx voltage is greater than 21 typ the positive harge-pump voltage is greater than typ 6 the 1 regulator output voltage falls elow of its nominal value the u output voltage falls elow 92 of its nominal value f any of the first three fault onditions persists for longer than the 2ms fault laning period the devie pulls low turns off all outputs and starts the autoretry timer f either ondition or ours the devie pulls low and turns off all outputs immediately the devie initi- ates startup only after the fault has leared f ondition 6 ours the devie pulls low ut does not turn off any of the outputs uring startup is mased and goes high as soon as the 1 regulator ontroller turns on this regulator turns on as soon as a eeeds the a undervoltage loout threshold autoretry hen the autoretry ounter finishes inrementing af ter 19s the devie attempts to turn on the oost onv erter and gate voltage regulators in the order shown in tale 1 the devie ontinues to autoretry as long as the fault ondition persists a fault on the 1 regulator output auses to go low ut does not result in the devie shutting down and going into autoretry current iit the effetive urrent limit of the oost onverter is redued y the internally ineted slope ompensation y an amount dependent on the duty yle of the onverter the effetive urrent limit is given y -12 lmff lm m 192 1 where lmff is the effetive urrent limit lm 11a or 22a depending on the oost onverter urre nt- limit option is the duty yle of the oost onv erter and m is the value of the apaitor at the m input stimate the duty yle of the onverter usi ng the formulas shown in the eign rocedure setion downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 15 max16929 automotive tft-lcd power supply with boost coverter te olte eultors egulator controller the 1 regulator ontroller delivers ma min to an eternal load onnet f to for a regulated 1 output for higher output apaility use an eternal npn transis- tor as shown in the tical lication ircuit the drive apaility of the regulator is then inreased y the ur- rent gain of the transistor h f hen using an eternal transistor use as the ase drive and onnet f to the transistors emitter ypass the ase to ground with a 1 f f erami apaitor f the oost output urrent is greater than ma on- net a i resistor etween and positivegate oltage egulator (g) the positive-gate voltage regulator inludes a p-hannel ft output stage to generate a regulated output etween and - 2 the regulator maintains auray over wide line and load onditions t is apale of at least 2ma of output urrent and inludes urrent-limit prote- tion is typially used to provide the tft-l gate drivers gate-on voltage the regulator derives its positive supply voltage from a noninverting harge pump a single-stage eample of whih is shown in the tical lication ircuit a high- er voltage using a multistage harge pump is possile as desried in the arge um setion egativegate oltage egulator (g) the negative-gate voltage regulator is an analog gain lo with an open-drain p-hannel output t drives an eternal npn pass transistor with a 6 i ase-to-emitter resistor see the a tranitor selection setion ts guaranteed ase drive soure urrent is at least 2ma l is typially used to provide the tft-l gate driv- ers gate-off voltage the output of the negative-gate voltage regulator ie the olletor of the eternal npn pass transistor has load- dependent ypassing reuirements onnet a erami apaitor etween the olletor and ground with the value shown in tale the regulator derives its negative supply voltage from an inverting harge pump a single-stage eample of whih is shown in the tical lication ircuit a more nega- tive voltage using a multistage harge pump is possile as desried in the arge um setion the eternal npn transistor is not short-iruit proteted to maintain proper pulldown apaility of eternal npn transistor and optimal regulation a minimum load of at least a is reommended on the output of the l regulator nale (p) se the enale input to enale and disale the oost setion of the devie onnet to a for normal operation and to to plae the devie in shut- down n shutdown the a supply urrent is redued to f a ofttart and upply euencing () hen enaled the oost output ramps up from a to its set voltage ne the oost output reahes of the set voltage and the soft-start timer epires the gate volt- age regulators turn on in the order shown in tale 1 the 1 regulator ontroller is enaled at the eginning of the oost onverters soft-start oth gate voltage regulators have a ms soft-start time the seond one turns on as soon as the output of the first reahes of its set voltage theral hutdon nternal thermal shutdown iruitry shuts down the devie immediately when the die temperature eeeds 16 n a 1 n thermal shutdown hysteresis prevents the devie from resuming normal operation until the die temperature falls elow 1 n ale 1. uppl euencing oro i i ir o ir x evie is in shutdown 1 l 1 1 l downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 1 max16929 automotive tft-lcd power supply with boost coverter te olte eultors design procedure buck converter inductor selection three ey indutor parameters must e speified for operation with the devie indutane value l indu- tor saturation urrent at and resistane to determine the indutane value selet the ratio of indutor pea-to-pea ripple urrent to average output urrent l first for l values that are too high the m urrents are high and therefore 2 losses are high se high-valued indutors to ahieve low l values typially indutane is proportional to resistane for a given paage type whih again maes 2 losses high for very low l values a good ompromise etween sie and loss is to selet a -to-6 pea-to-pea ripple urrent to average-urrent ratio f etremely thin high-resistane indutors are used as is ommon for l-panel appliations the est l an inrease etween and 1 the sie of the indutor is deter- mined as follows - l and l f = = where is the input voltage is the output volt- age is the output urrent e is the effiieny of the u onverter is the duty yle and f is 21m the swithing freueny of the u onverter the effiieny of the u onverter an e estimated from the tical oerating aracteritic and aounts for losses in the internal swith ath diode indutor and apaitor to ensure the u onverter does not shut down during load dump input-voltage transients to 2 an indutor value larger than alulated aove should e used tale 2 lists the minimum indutane that should e used for proper operation during load dump the saturation urrent rating at must e high enough to ensure that saturation an our only aove the mai- mum urrent-limit value find a low-loss indutor having the lowest possile resistane that fits in the allotted dimensions capacitor selection the input and output filter apaitors should e of a low- type tantalum erami or low- eletrolyti and should have m ratings greater than 2 m l 1- 12 = + for the input apaitor tm l 12 = for the output apaitor where is the duty yle given aove the output voltage ontains a ripple omponent whose pea-to-pea value depends on the value of the and apaitane of the output apaitor and is approi- mately given y d l d d a d l a l f ? = iode selection the ath diode should e a hotty type to minimie its voltage drop and maimie effiieny the diode must e apale of withstanding a reverse voltage of at least the maimum input voltage in the appliation the diode should have an average forward urrent rating greater than 1- where is the duty yle given aove n addition ensure that the pea urrent rating of the diode is greater than t l 1 2 ? ? + ? ? ? ? ale 2. iniu buck inuctor value reuire for oral operation uring oa up b v ob (v) b i ob () i () 12 2 6 12 2 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 1 max16929 automotive tft-lcd power supply with boost coverter te olte eultors boost converter inductor selection three ey indutor parameters must e speified for operation with the devie indutane value l indu- tor saturation urrent at and resistane to determine the indutane value selet the ratio of indutor pea-to-pea ripple urrent to average input urrent l first for l values that are too high the m urrents are high and therefore 2 losses are high se high-valued indutors to ahieve low l values typially indutane is proportional to resistane for a given paage type whih again maes 2 losses high for very low l values a good ompromise etween sie and loss is to selet a -to-6 pea-to-pea ripple urrent to average-urrent ratio f etremely thin high-resistane indutors are used as is ommon for l-panel appliations the est l an inrease etween and 1 the sie of the indutor is deter- mined as follows a a l and l f a 1 ? where a is the input voltage is the output voltage is the output urrent is the average oost input urrent e is the effiieny of the oost onverter is the duty yle and f is 22m the swithing freueny of the oost onverter the effiieny of the oost onverter an e estimated from the tical oerating aracteritic and aounts for losses in the internal swith ath diode indutor and apaitor capacitor selection the input and output filter apaitors should e of a low- type tantalum erami or low- eletrolyti and should have m ratings greater than m l 12 for the input apaitor 2 m l 12 1 ? for the output apaitor where and are the input urrent and duty yle given aove the output voltage ontains a ripple omponent whose pea-to-pea value depends on the value of the and apaitane of the output apaitor and is approimately given y d l d d a l 1 2 ? a t f ? where and are the input urrent and duty yle given aove ectifier iode the ath diode should e a hotty type to minimie its voltage drop and maimie effiieny the diode must e apale of withstanding a reverse voltage of at least the diode should have an average forward urrent rating greater than 1- where and are the input urrent and duty yle given aove n addition ensure that the pea urrent rat- ing of the diode is greater than l 1 2 ? ? ? ? ? ? outputoltage selection the output voltage of the oost onverter an e adust- ed y using a resistive voltage-divider formed y t and ttm onnet t etween the output and f and onnet ttm etween f and elet ttm in the 1 i to i range alulate t with the following euation t ttm f 1 ? where f the oost onverters feeda set point is 1 lae oth resistors as lose as possile to th e devie and onnet ttm to the analog ground plane oop compensation hoose m to set the high-freueny integrator gain for fast transient response hoose m to set the integrator ero to maintain loop staility for low- output apaitors use tale to selet the initial values for m and m se a 22pf apaitor in paral- lel with m m downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 18 max16929 automotive tft-lcd power supply with boost coverter te olte eultors ale 3. opensation oponent values to further optimie transient response vary m in 2 steps and m in steps while oserv- ing transient-response waveforms the ideal transient response is ahieved when the output settles uily with little or no overshoot onnet the ompensation networ to the analog ground plane se the following formula to alulate the value fo r m m 9 1 -6 l tt - a pchannel t selection the p-hannel ft used to gate the oost onverters input should have low on-resistane onnet a resistor etween the soure and gate of the ft nder normal operation arries a gate drive urrent of f a and the resulting gate soure voltage turns on the ft hen the gate drive is removed under a fault ondition or in shutdown leeds off harge to turn off the ft ie to produe the needed to turn on the ft egulator controller npn ipolar transistor selection there are two important onsiderations in seleting the pass npn ipolar transistor urrent gain h f and power dissipation elet a transistor with an h f high enough to ensure adeuate drive apaility this ondition is satis- fied when h f 1 is greater than the maimum load urrent the regulator an soure ma min the transistor should e apale of dissipating a - t lamax where t 1 or ypass to ground with a 1 f f erami apaitor for appliations in whih the oost output urrent eeeds ma onnet a i resistor from to ground supply considerations a needs to e at least for the regulator to operate properly charge pups selecting the umer of chargepump stages for most appliations a single harge-pump stage is suffiient as shown in the tical lication ircuit onnet the flying apaitors to lx the output voltages generated on the storage apaitors are given y 2 tt - 2 - tt - 2 where is the positive supply for the positive-gate volt- age regulator and is the negative supply for the neg- ative-gate voltage regulator here larger output v oltages are needed use multistage harge pumps however t he maimum harge-pump voltage is limited y the asol ute maimum ratings of and figure 2 and figure show the onfiguration of a multistage harge pump for oth positive and negative output voltages for mutistage harge pumps the output voltages are n tt - 2 -n tt - 2 for highest effiieny hoose the lowest numer of harge-pump stages that meets the output reuirement igure 2 ultitage arge um for oitive outut oltage igure ultitage arge um for egative outut oltage v (v) 1 i () 2 2 v i (v) i () 1 () r ov (k i ) 9 ov (p) 22 1 oi (p) 2 v sh v cp lxp v cn lxp downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 1 max16929 automotive tft-lcd power supply with boost coverter te olte eultors the numer of positive harge-pump stages needed is given y t tt n 2 ? ? and the numer of negative harge-pump stages is given y l t tt n 2 + ? where n is the numer of positive harge-pump stag- es n is the numer of negative harge-pump stages is the positive-gate voltage regulator output volt- age l is the negative-gate voltage regulator output voltage is the oost onverters output voltage is the forward-voltage drop of the harge-pump diode tt is the forward drop of the hotty diode of the oost onverter and t is the dropout margin for the regulator se t for the negative voltage regulator and t 2 at 2ma for the positive-gate voltage regulator lying capacitors nreasing the flying apaitor x value lowers the effetive soure impedane and inreases the output urrent apaility nreasing the apaitane indefi- nitely has a negligile effet on output urrent apaility eause the internal swith resistane and the diode impedane plae a lower limit on the soure impedane a 1 f f erami apaitor wors well in most low-urrent appliations the voltage rating of the flying apaitors for the positive harge pump should eeed and that for the negative harge pump should eeed the magnitude of chargepump output capacitor nreasing the output apaitane or dereasing the redues the output-ripple voltage and the pea-to-pea transient voltage ith erami apaitors the output- voltage ripple is dominated y the apaitane value se the following euation to approimate the reuired output apaitane for the noninverting harge pump onneted to la t l f where t is the output apaitor of the harge pump is the duty yle of the oost onverter la is the load urrent of the harge pump f is the swithing freueny of the oost onverter and l is the pea-to-pea value of the output ripple for the inverting harge pump onneted to use the following euation to approimate the reuired output apaitane la t l 1- f where t is the output apaitor of the harge pump is the duty yle of the oost onverter la is the load urrent of the harge pump f is the swithing freueny of the oost onverter and l is the pea-to-pea value of the output ripple chargepump ectifier iodes se high-speed silion swithing diodes with a urrent rating eual to or greater than two times the average harge-pump input urrent f it helps avoid an etra stage some or all of the diodes an e replaed with hotty diodes with an euivalent urrent rating positivegate oltage egulator outputoltage selection the output voltage of the positive-gate voltage regula- tor an e adusted y using a resistive voltage-divider formed y t and ttm onnet t etween the output and f and onnet ttm etween f and elet ttm in the 1 i to i range alulate t with the following euation t ttm f 1 = ? where is the desired output voltage and f 1 the regulated feeda voltage for the regulator lae oth resistors as lose as possile to the devie avoid eessive power dissipation within the internal pm devie of the regulator y paying attention to the voltage drop aross the drain and soure the amount of power dissipation is given y l - lamax where is the noninverting harge-pump output volt- age applied to the drain is the regulated output voltage and lamax is the maimum load urrent staility euirements the positive-gate voltage regulator reuires a minimum output apaitane for staility for an ou tput downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 2 max16929 automotive tft-lcd power supply with boost coverter te olte eultors voltage of to - 2 and an output urrent of 1ma to 1ma use a minimum apaitane of f f egativegate oltage egulator outputoltage selection the output voltage of the negative-gate voltage regula- tor an e adusted y using a resistive voltage-divider formed y t and ttm onnet t etween f and fl and onnet ttm etween fl and the olletor of the eternal npn transistor elet t greater than 2 i to avoid loading down the ref- erene output alulate ttm with the following euation fl l ttm t f fl ? = ? where l is the desired output voltage f 12 and fl 2 the regulated feeda voltage of the regulator pass transistor selection the pass transistor must meet speifiations for urrent gain h f input apaitane olletor-emitter saturation voltage and power dissipation the transistors urrent gain limits the guaranteed maimum output urrent to lamax fm h = ? where is the minimum guaranteed ase-drive ur- rent is the transistors ase-to-emitter forward volt- age drop and is the pulldown resistor onneted etween the transistors ase and emitter furthermore the transistors urrent gain inreases the regulators loop gain see the stailit reuirement setion so eessive gain destailies the output the transistors saturation voltage at the maimum output urrent determines the minimum input-to-output volt- age differential that the regulator an support also the paages power dissipation limits the usale maimum input-to-output voltage differential the maimum power- dissipation apaility of the transistors paage and mounting must eeed the atual power dissipated in the devie the power dissipated euals the maimum load urrent lamaxl multiplied y the maimum input-to-output voltage differential l l - lamaxl where l is the regulated output voltage on the olle- tor of the transistor is the inverting harge-pump output voltage applied to the emitter of the transistor and lamaxl is the maimum load urrent ote that the eternal transistor is not short-iruit proteted staility euirements the devies negative-gate voltage regulator uses an internal transondutane amplifier to drive an eternal pass transistor the transondutane amplifier th e pass transistor the ase-emitter resistor and the output apaitor determine the loop staility the transondutane amplifier regulates the output volt- age y ontrolling the pass transistors ase urrent the total loop gain is approimately a f l f t la h a 1 ? + where t is 26m at room temperature and a is the urrent through the ase-to-emitter resistor for the devie the ias urrent for the negative-gate voltage regulator is 1ma therefore the ase-to-emitter resistor should e hosen to set 1ma ias urrent 1ma 1ma = = = ? se the losest standard resistor value of 6 i the output apaitor and the load resistane reate the dominant pole in the system owever the internal amplifier delay pass transistors input apaitan e and the stray apaitane at the feeda node reate additional poles in the system and the output apaitors generates a ero for proper operation use the fol- lowing euations to verify that the regulator is properly ompensated 1 first determine the dominant pole set y the regula- tors output apaitor and the load resistor lamaxl ll tl tl f 2 = the unity-gain rossover freueny of the regulator is f a l f ll 2 the pole reated y the internal amplifier delay is approimately 1m f lam 1m et alulate the pole set y the transistors input apaitane the transistors input resistane and the ase-to-emitter pullup resistor downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 21 max16929 automotive tft-lcd power supply with boost coverter te olte eultors l 1 f 2 = where m f t m g h 2 f g = = g m is the transondutane of the pass transistor and f t is the transition freueny oth parameters an e found in the transistors data sheet eause is muh greater than the aove euation an e simplified l 1 f 2 = ustituting for and yields t l f f f h = et alulate the pole set y the regulators feed- a resistane and the apaitane etween fl and inluding stray apaitane lfl fl t ttm 1 f 2 = where fl is the apaitane etween fl and and is eual to pf t is the upper resistor of the regulators feeda divider and ttm is the lower resistor of the divider et alulate the ero aused y the output apai- tors tl 1 f 2 = where is the euivalent series resistane of tl to ensure staility mae tl large enough so the rossover ours well efore the pole s and ero alulated in steps 2 to the poles in s teps and generally our at several m and using erami apaitors ensures the ero also ours at several m laing the rossover freueny el ow is suffiient to avoid the amplifier delay p ole and generally wors well unless unusual omponent hoies or etra apaitanes move one of the other poles or the ero elow 1m tale is a list of reommended minimum output apai- tane for the negative-gate voltage regulator and a re appliale for output urrents in the 1ma to 1ma range applications nforation poer dissipation an s maimum power dissipation depends on the ther- mal resistane from the die to the amient environment and the amient temperature the thermal resistane depends on the paage opper area other thermal mass and airflow more opper ooler amient air and more airflow inrease the possile dis- sipation while less opper or warmer air dereases the s dissipation apaility the maor omponents of power dissipation are the power dissipated in the u onverter oost onverter positive-gate voltage regula- tor negative-gate voltage regulator and the 1 regulator ontroller uc conerter n the u onverter ondution and swithing losses in the internal mft are dominant stimate these losses using the following formula lx t d 2 lx t t t f f where t is the output urrent is the duty yle of the u onverter lx is the on-resistane of the internal high-side ft is the input voltage t t f is the time is taes for the swith urrent and voltage to settle to their final values during the rising and falling transitions and f is the swithing freueny of the u onverter lx is 1m i typ and t t f is ns 6ns 9ns at 12 ale 4. iniu output apacitance s. output voltage range for egatieate voltage regulator (i o 1 to 15) o vo r ii o i () -2 r l r - 22 - r l r - 1 - r l r -1 1 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 22 max16929 automotive tft-lcd power supply with boost coverter te olte eultors oost conerter ower dissipation in the oost onverter is primarily due to ondution and swithing losses in the low-side ft ondution loss is produed y the indutor urrent flowing through the on-resistane of the ft during the on-time withing loss ours during swithing transi- tions and is a result of the finite time needed to fully turn on and off the ft ower dissipation in the oost on- verter an e estimated with the following formula lx max d 2 lx max f t - t f- t - t f- where max is the maimum epeted average input ie indutor urrent is the duty yle of the oost onverter lx is the on-resistane of the internal low-side ft is the output voltage and f is the swithing freueny of the oost onverter lx is 11m i typ and f is 22m the voltage and urrent rise and fall times at the lx node are eual to t - voltage rise time t f- voltage fall time t - urrent rise time and t f- urrent fall time and are determined as follows tt - - t + tt f- f- t + max - - t max f- f- t - f- - and f- are the voltage and urrent slew rates of the lx node and are supply dependent se tale to determine their values positiegate oltage egulator se the lowest numer of harge-pump stages possile in supplying power to the positive-gate voltage regulator oing so minimies the drain-soure voltage of the inte- grated pm swith and power dissipation the power dissipated in the swith is given as - lamax nsure that the voltage on does not eeed the overvoltage threshold as given in the lectrical aracteritic tale egatiegate oltage egulator se the lowest numer of harge-pump stages possile to provide the negative voltage to the negative-gate voltage regulator stimate the power dissipated in the negative-gate voltage regulator using the following l a - where is the ase-emitter voltage of the eternal npn ipolar transistor and is the urrent soured from to the ias resistor and to the ase of the transistor whih is given y l f h 1 + ./. egulator controller the power dissipated in the 1 regulator ontroller is given y a - t - where t 1 or is the ase-emitter voltage of the eternal npn ipolar transistor and is the urrent soured from to the ase of the transistor is given y la f h 1 + where la is load urrent of the 1 regulator ontroller and h f is the urrent gain of the transistor ale 5. voltage an urrent le rates s. uppl voltage v i (v) vo rr r rii vo r rv (vns) i vo r v (vns) rii rr r ri (ns) i rr r i (ns) 2 1 1 1 2 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 23 max16929 automotive tft-lcd power supply with boost coverter te olte eultors total poer issipation the total power dissipated in the paage is the sum of the losses previously alulated therefore total power dissipation an e estimated as follows t lx lx l ahieve maimum heat transfer y onneting the ep osed pad to a thermal landing pad and onneting the the rmal landing pad to a large ground plane through thermal vias ayout considerations areful layout is ritial in ahieving stale and optimied performane follow the following guidelines for good layout 1 lae deoupling apaitors as lose as possile to the devie onnet the power ground planes and the analog ground plane together at one point lose to the devie 2 onnet input and output apaitors to the power ground planes onnet all other apaitors to the analog ground plane eep the high-urrent paths as short and wide as possile eep the path of swithing urrents short lae the feeda resistors as lose to the as possile onnet the negative end of the resistive divider and the ompensation networ to the analog ground plane oute the high-speed swithing node lx and lx away from sensitive analog nodes f f f fl f and f efer to the max16929 valuation it data sheet for a reommended layout ordering nforationelector guide ote ll device are ecified over te - to 15 oerating temerature range / denote an automotive ualified art enote a lead-free/ros-comliant acage oed ad chip nforation im package nforation for the latest paage outline information and land patterns footprints go to .aiic.copackages ote that a or - in the paage ode indiates o status only aage drawings may show a different suffi harater ut the drawing pertains to the paage regardless of o status r ror v r (v) b v ob (v) b i ob () boo i i () i max16929a 2 1 2 t- max16929 1 2 1 2 t- max16929 1 2 1 2 t- max16929 2 2 t- max16929 12 2 t- max16929f 1 2 2 t- max16929 1 12 2 t- max16929 1 2 2 t- max16929 1 12 2 t- o oi o. r o. 2 t- 2m1 2118 14 downloaded from: http:///
???????????????????????????????????????????????????????????????? maxim integrated products 24 max16929 automotive tft-lcd power supply with boost coverter te olte eultors typical application circuit drvn v cn v gl ina pgood fbgl gh fbgh 4v to 28v outb bst inb lxbfbb enb avl gnd cp lxp optional v reg 1.8v/3.3v ina outb compi compv gate lxppgndp fbp l p v sh c compv c compi r compv refgnd positive gate voltage regulator negative gate voltage regulator bandgap reference 3.3v/5v buck oscillator v sh v gh v cn 1.8v/3.3v regulator controller dr fb v in a to 18v boost control enp seq max16929 downloaded from: http:///
max16929 automotive tft-lcd power supply with boost coverter te olte eultors aim cannot aume reoniilit for ue of an circuitr oter tan circuitr entirel emodied in a aim roduct o circuit atent licene are imlied aim reerve te rigt to cange te circuitr and ecification itout notice at an time te arametric value min and ma limit on in te lectrical aracteritic tale are guaranteed oter arametric value uoted in ti data eet are rovided for guidance ai ntegrated products an gariel drive unnyvale ca 25 ? 212 maim ntegrated roduts maim is a registered trademar of maim ntegrated roduts n evision istory rviio br rviio riio 11 nitial release 1 911 emoved from the f to range in the olute aimum rating 2 2 112 orreted the m formula in the oo omenation setion 1 downloaded from: http:///

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