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product structure silicon monolithic integrated circuit this product is not designed prot ection against radioactive rays 1/30 tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 14? 001 datashee t bd6142amuv ch 1 ch 2 ch 3 ch 4 ch 5 ch 6 ch 7 ch 8 ov p 10 serial x 8 parallel (80pcs) 20ma abc lx lx 2.2f/50v fau lt vin 10h 10f enab le pwm 2.1v to vin co mp 1k ? iset 36k ? gnd pgnd pwm f pw m =100hz~25khz vdc pgnd 22n f 2.2m ? 68k ? vout 2.2f gnd pgnd fset test 56k ? 1nf 7v to 27v reset 8-channel white led driver with integrated fet for up to 80 leds bd6142amuv general description this ic is white led driver ic with pwm step-up dc/dc converter that can boost max 41v and current driver that can drive max 30ma. the wide and precision brightness can be controlled by external pwm pulse. this ic has very accurate current drivers, and it has few current errors between each strings. so, it will be helpful to reduce brightness spots on the lcd panel. small package is suited for saving space. features ? high accuracy & good matching current drivers 8ch (max30ma/ch) ? integrated 50v power nch mosfet ? soft start function ? drive up to 11 leds in series, 8 strings in parallel ? rich safety functions ? over-voltage protection ? external sbd open detect / output short protection ?over current limit ? ch terminal open / gnd short protect ? ch over voltage protect / led short protect ? thermal shutdown ?uvlo ? analog brightness control typical application circuit (8 parallel) key specifications ? operating power supply voltage range: 4.2v to 27.0v ? led maximum current: 30ma (max.) ? quiescent current: 1.6 a (typ.) ? switching frequency: 1.25mhz(typ.) ? operating temperature range: -40 to +85 package w(typ.) x d (typ.) x h(max.) vqfn024v4040 4.00mm x 4.00mm x 1.00mm applications all medium sized lcd equipments, backlight of notebook pc, net book, monitor, light, portable dvd player, light source etc. figure 2. typical application circuit figure 1. package vqfn024v4040
2/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 absolute maximum ratings (ta=25 ) parameter symbol ratings unit condition terminal voltage 1 vmax1 7 v vdc, iset, abc, comp, fset, test, fault terminal voltage 2 vmax2 45 v ch1 to ch8, lx, ovp terminal voltage 3 vmax3 30.5 v vin, enable terminal voltage 4 vmax4 15 v pwm power dissipation 1 pd1 500 *1 mw power dissipation 2 pd2 780 *2 mw power dissipation 3 pd3 1510 *3 mw operating temperature r ange topr -40 to +85 storage temperature range tstg -55 to+150 *1 reduced 4.0mw/ with ta>25 when not mounted on a heat radiation board. *2 1 layer (rohm standard board) has been mounted. copper foil area 0mm 2 , when it?s used by more than ta=25 , it?s reduced by 6.2mw/ . *3 4 layer (jedec compliant board) has been mounted. copper foil area 1layer 6.28mm 2 , copper foil area 2 to 4layers 5655.04mm 2 , when it?s used by more than ta=25 , it?s reduced by 12.1mw/ . recommended operating rating (ta=-40 to +85 ) parameter symbol limits unit conditions min. typ. max. power supply voltage vin 4.2 12.0 27.0 v electrical characteristics (unless otherwise specified, vin=12v, ta = +25 ) parameter symbol limits unit conditions min. typ. max. [general] quiescent current iq - 1.6 4.4 a enable=0v current consumption idd - 3.6 5.4 ma ovp=0v,iset=36k ? max. output voltage mov - - 41 v under voltage lock out uvlo 3. 1 3.7 4.1 v vin falling edge [enable terminal] low input voltage range enl 0.0 - 0.8 v high input voltage range1 enh 2.0 - vin v pull down resistor enr 100 300 500 k ? enable=3v output current eniout - 0 2 a enable=0v [pwm terminal] low input voltage range pwml 0.0 - 0.8 v high input voltage range2 pwmh 1.3 - 12.0 v pull down resistor pwmr 100 300 500 k ? pwm=3v output current pwmiout - 0 2 a pwm=0v [fault] nch ron ffcr - - 3 k ? enable =pwm=3v, ovp=2v [regulator] vdc voltage vreg 4.2 5.0 6.0 v no load, vin > 6v 3/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 electrical characteristics ? continued (unless otherwise specified, vin=12v, ta = +25 ) parameter symbol limits unit conditions min. typ. max. [switching regulator] led control voltage vled 0.64 0.80 0.96 v switching frequency accuracy fs w 1.00 1.25 1.50 mhz fset=56k ? duty cycle limit duty 91.0 95.0 99.0 % ch1-8=0.3v, fset=56k ? lx nch fet ron ron - 0.48 0.58 ? ilx=80ma [protection] over current limit ocp 1.5 2.5 - a *1 over voltage limit input ovp 1.16 1.20 1.24 v detect voltage of ovp output short protect ovpfault 0.02 0. 05 0.08 v detect voltage of ovp ovp leak current ovil - 0.1 1.0 a ch terminal over voltage protect accuracy vsc -15 0 +15 % vsc=5v [current driver] led maximum current ilmax - - 30 ma led current accuracy ila ccu - - 2.5 % iled=20ma (36k ? ) led current matching ilmat - - 2.5 % (max led current ? min led current)/ ideal current (20ma) iled=20ma led current matching2 ilmat2 - - 1.5 % ? each led current/average (ch1- 8) ? iled=20ma led current limiter ilocp - 0 0.1 ma current limit value at iset resistance 1k ? setting iset voltage iset - 0.733 - v led current accuracy2 ilaccu2 - 3.0 - % iled=20ma, abc=0.733v *1 this parameter is tested with dc measurement. 4/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 pin vdc gnd a pin vin pgnd b pin gnd c pin vin gnd d pin gnd e 5.5v clump pin pgnd f pin pgnd g gnd pin descriptions pin esd type pin no. pin name io function terminal diagram 1 enable in pwm input pin for power on/off or power control e 2 test in test signal (pull down 100k ? within ic) e 3 fset in resister connection for frequency setting a 4 abc in analog brightness control c 5 gnd - gnd for switching regulator b 6 pwm in pwm input pin for power on/off only driver e 7 ch8 in current sink for ch8 c 8 ch7 in current sink for ch7 c 9 ch6 in current sink for ch6 c 10 ch5 in current sink for ch5 c 11 iset in resister connection for led current setting a 12 ch4 in current sink for ch4 c 13 ch3 in current sink for ch3 c 14 ch2 in current sink for ch2 c 15 ch1 in current sink for ch1 c 16 ovp in detect input for sbd open and ovp c 17 pgnd - pgnd for switching tr d 18 19 lx out switching tr drive terminal f 20 out switching tr drive terminal f 21 fault out fault signal c 22 comp out erramp output a 23 vin in battery input g 24 vdc out regulator output / internal power-supply c - thermal pad - heat radiation pad of back side connect to gnd figure 3. pin esd type 5/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 block diagram pin number 24pin figure 4. block diagram enable lx lx pgnd pgnd vin vdc reg tsd internal powe r supply clam p internal power control uvlo internal reset faul t detecto r fault output short protect output over voltage protect led terminal open/short detector led return select ch1 ch 2 ch 3 ch 4 ch 5 ch 6 ch 7 ch 8 ovp + - current sense over current protect soft start control sense osc + erramp pwm co mp 8ch gnd current driver + - pwm iset iset resistor driver comp test fset abc clamp 6/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 typical performance curves 7/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 application example figure 11, figure 12 and figure 13 are application examples (15.4inch and 12inch and 10.1inch model). recommended schematics and layout are shown in p22. figure 11. bd6142amuv application example (8 parallel) 8/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15? 001 figure 12. bd6142amuv application example (6 parallel) figure 13. bd6142amuv application example (3 parallel) bd6142amuv ch 1 ch 2 ch 3 ch 4 ch 5 ch 6 ch 7 ch 8 ov p 10 serial x 3 parallel (30pcs) 20ma abc lx lx 2.2f/50v fault vin 10h 10f 4.2v to 27v enab le reset pwm 2.1v to vin co mp 1k ? iset 36k ? gnd pgnd pwm f pw m =100hz~25khz vdc pgnd 22nf 2.2m ? 68k ? vout 2. 2 f gnd pgnd fset test 11 0 k ? 1nf bd6142amuv ch1 ch2 ch 3 ch 4 ch 5 ch 6 ch 7 ch 8 ov p 9 serial x 6 parallel (54pcs) 20ma abc lx lx 2.2f/50v fault vin 10h 10f 7v to 27v enab le reset pwm 2.1v to vin co mp 1k ? iset 36k ? gnd pgnd pw m f pw m =100hz~25khz vdc pgnd 22nf 2.2m ? 73.2k ? vout 2. 2 f gnd pgnd fset test 56k ? 1nf 9/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 functional descriptions 1) pwm current mode dc/dc converter while this ic is power on, the lowest vo ltage of ch1, 2, 3, 4, 5, 6, 7, 8 is detected, pwm duty is decided to be 0.8v and output voltage is kept invariably. as for the inputs of the pwm comparator as the feature of the pwm current mode, one is overlapped with error components from the error amplifier, and the other is overlapped with a current sense signal that controls the inductor current into slope waveform to prevent s ub harmonic oscillation. this output controls internal nch tr via the rs latch. in the period where inte rnal nch tr gate is on, energy is accumulated in the external inductor, and in the period where internal nch tr gate is off, energy is transferred to the output capacitor via external sbd. this ic has many safety functions, and their det ection signals stop switching operation at once. 2) pulse skips control this ic regulates the output voltage using an improved pulse-skip. in ?pulse-ski p? mode the error amplifier disables ?switching? of the power stages when it detects low outp ut voltage and high input voltage. the oscillator halts and the controller skip switching cycles. the error amplifier reactivate s the oscillator and starts switching of the power stages again when this ic detects low input voltage. at light loads a conventional ?pulse-skip? regulation mode is used. the ?pulse- skip? regulation minimizes the operating current because this ic does not switch continuously and h ence the losses of the switchi ng are reduced. when the error amplifier disables ?switching?, the load is also isolated from the input. this improved ?pulse-skip? control is also referred t o as active-cycle control. figure 14. pulse-skip 3) soft start this ic has soft start function. the soft start function prevents large coil current. rush current at turning on is prevented by the soft start function. after enable, pwm is changed ?l? ? ?h?, and uvlo is detected, so ft start becomes effective for within typ 4.3ms and soft start doesn't become effective even if enable is changed ?l? ? ?h? after that. figure 15. soft start 4) fault when the error condition occurs, boost operating is stopped by the protection function, and t he error condition is outputted from fault. after power on, when the protection functi on is operating under about 4.3ms(typ.) have passed. once enable change to ?l?, fault status is reset object of protect function is as shown below. - over-voltage protection (ovp) - thermal shut down (otp) - over current limit (ocp) - output short protect - led short (latch) - led open (latch) figure 16. fault operating description off normal boost stop normal off normal un-detection detect un-detect typ4.3 ms faul t protection function(ovp, tsd, ocp) boost operating vdc pwm ?x? ?x? ?h? ?l? ?h? ?l? ?h? mask un-detect protection function(led open, led short) detect un-detect latch typ100 s enable pwm vout led current lx 20ma duty 20% @1.25mhz(typ) pulse skip pwm uvl o enable max 1ms typ 4.3ms off on off on vdc soft star t enable max 1ms off on off on vdc soft start pwm uvl o off t1 t2 s oft star t time=t1+t2=4.3ms typ. 10/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 protection protection table case failure mode detection mode fail channel good channel vout regulated by fault terminal 1 led short connected ch1 ch1 > vsc(5v) led current stop and dc/dc feedback doesn?t return ch2 to ch8 normal highest vf of ch2 to ch8 ?h? ? ? l ? (latch) 2 led open connected ch1 ch1 < 0.2v and vout > vovp led current stop and dc/dc feedback doesn?t return ch2 to ch8 normal highest vf of ch2 to ch8 ?h? ? ? l ? (latch) 3 vout/lx gnd short ovp < 50mv fault change from l to h, and switching is stopped. when ovp>50mv, fault return l - ?h? ? ? l ? 4 output led stack voltage too high vout > vovp fault change from l to h, and switching is stopped. even if ovp<1.2v, fault don?t return l - ?h? ? ? l ? 5 lx current too high ocp > 2.5a or otp > 130 ?c fault change from l to h, and switching is stopped. even if ic return normal status, fault don?t return l - ?h? ? ? l ? ? over voltage protection (ovp) at such an error of output op en as the output dc/dc and the led is not c onnected to ic, the dc/dc will boost too much and the ovp terminal exceed the absolute maximum ratings, and may destruct the ic. therefore, when ovp terminal becomes sensing voltage or higher, the over voltage limit pr otection works, and turns off t he switching tr, and dc/dc will be stopped. at this moment, the ic changes from activation into non-ac tivation, and the output voltage goes down slowly. and, when the feedback of ch1 isn?t returned, so t hat vout will return normal voltage. figure 17. ovp operating description vout ch1 volta g e ch1 connection ch2 connection feedbac k enable, pwm connec t ch1 ch1 ch2 connect open ch1 curren t 20m a 0m a ch2 curren t 20m a 0m a ovp signal hysteresis(typ 2.5%) 11/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 this section is especially mentioned here because the spec sh own electrical characteristic is necessary to explain this section. over voltage limit min 1.16v typ 1.20v max 1.24v led control voltage min 0.64v typ 0.80v max 0.96v led terminal over voltage protect min 4.25v typ 5.00 v max 5.75v 1. calculate the conditions that the total value of led vf is max. example) in the case of serial 8 leds with vf=2.9v(min), 3.2v(typ), 3.5v(max) => 3.5v x 8=28v 2. then calculate the biggest value of output with the following formula. the biggest value of output = the biggest value calculated for 1 + the biggest value of led terminal voltage. (0.96v) example) the biggest value of output = 28v + 0.96v =28.96v 3. set the smallest value of over voltage larger than the biggest value of output. if over voltage is closer to the total value of vf, it could be occurred to detect over voltage by ripple, noise, and so on. it is recommended that some margins should be left on the difference between over voltage and the total value of vf. this time around 6% margin is placed. example) against the biggest value of output = 28.96v, the smallest value of over voltage = 28.96v x 1.06 = 30.70v ic over voltage limit min=1.16v, typ=1.20v, max=1.24v typ = 30.70v (1.20v/1.16v) = 31.76v max = 31.76v (1.26v/1.20v) = 33.35v 4. the below shows how to control resistor setting over voltage please fix resistor high between ovp te rminal and output and then set over voltage after changing resistor between ovp terminal and gnd. while pwm is off, output voltage decreas es by minimizing this resistor. due to the decrease of output voltage, ripple of output voltage increases, and singing of output condenser also becomes bigger. example) selecting ovp resistor. ? ovp resistor selection (example. 1) vf=3.5v max, serial = 7 led ovp = 1.2v, r1 = 2.2m ? , r2 = 95.3k ? vout = 1.2 (2.2m ? + 95.3k ? )/ 95.3k ? = 28.90v (example. 2) vf=3.5v max, serial = 8 led ovp = 1.2v, r1 = 2.2m ? , r2 = 82k ? vout = 1.2 (2.2m ? + 82k ? )/ 82k ? = 33.40v (example. 3) vf=3.5v max, serial = 9 led ovp = 1.2v, r1 = 2.2m ? , r2 = 73.2k ? vout = 1.2 (2.2m ? + 73.2k ? )/ 73.2k ? = 37.27v (example. 4) vf=3.5v max, serial = 10 led ovp = 1.2v, r1 = 2.2m ? , r2 = 68k ? vout = 1.2 (2.2m ? + 68k ? )/ 68k ? = 40.02v ? external sbd open detect / output short protection in the case of external sbd is not connected to ic, or vout is shorted to gnd, the coil or internal tr may be destructed. therefore, at such an error as ovp becoming 50mv(typ.) or below, turns off the output tr, and prevents the coil and the ic from being destructed. and the ic changes from activation into non-activation, and current does not flow to the coil (0ma). ? thermal shut down this ic has thermal shut down function. the thermal shut down works at 130 ? c (typ.) or higher, and the ic changes from activation into non-activation. ovp terminal vout r1 r2 12/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 operating of the application deficiency 1)when 1 led or 1string open during the operating the led string which became open isn't lighting, but other led strings are lighting. then led terminal is 0voutput boosts up to the over voltage pr otection voltage. when over voltage is detected, the feedback of open string isn?t returned, so that vout will return normal voltage. 2)when led short-circuited in the plural all led strings is turned on unless ch1 to 8 terminal voltage is more than 5v(typ.). when it was more than 5v only the st rings which short-circuited is turn ed off normally and led current of other lines continue to turn on. short line(ch1) current is chang ed from 20ma to 0.05ma(typ.), so ch1 terminal don?t heat. 3)when schottky diode remove all led strings aren?t turned on. also, ic and a switching tr ansistor aren't destroyed because boost operating stops by the schottky diode open protected function. ch 1 ch 2 ch 1 ch 2 figure 18. led open protect figure 19. led short protect vout ch1 voltage ch1 connection ch2 connection feedback enable, pwm ch1 curren t connect ch1 off ch2 connect o p en 20ma 0ma ch2 curren t 20ma 0ma ch1 ovp ch1 enable 100 s ch1terminal feedback ch1 current ch1 ch2 ch2 current 20ma 20ma 0.05ma(typ.) vout 0.8v led short ch2 terminal 0.8v typ 5v ch1>c 100 s( typ.) 13/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 control signal input timing timing sequence1 referring to figure 20, the recommended turn ?on? sequence is vin followed by enable and pwm. the recommended turn ?off? sequence is enable and pwm followed by vin. this sequence is recommendation. timing sequence2 referring to figure 21, the recommended turn ?on? sequence is vin, enable followed by pwm. the recommended turn ?off? sequence is followed enable and vin by pwm. enable, pwm vin power on power off led ic timing sequence for pwm control turn-on vin 2 to 5v min 0 s pwm enable min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0v led ic timing sequence for pwm control turn-off pw m 2 to 5v min 0 s vin enable min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0v figure 20. timing sequence1 pwm vin, enable power on power off enable 2 to 5v min 0 s vin pwm min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0 v vin 2 to 5v min 0 s enable pwm min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0v led ic timing sequence for pwm control turn-on figure 21. timing sequence2 led ic timing sequence for pwm control turn-off *other signal is input after a signal turned on. *other signal is input after a signal turned off. *other signal is input after a signal turned off. *other signal is input after a signal turned on. 14/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 timing sequence3 referring to figure 22, the recommended turn ?on? sequence is vin, pwm followed by enable. the recommended turn ?off? sequence is followed enable and vin by pwm. vin wake up speed figure 23. control signal timing in case, there is pwm off status (min: 10ms) during operation as figure 24, enable should turn from ?h? to ?l? as figure 24. if pwm stops and vout voltage is dropped, this ic will be conditi on of current limiter when pwm starts (no soft start). if soft start isn?t needed, reset is no need. vin min. 100s 4.1 v 1 2 figure 24. pwm stop and enable turn ?off? pwm off vin enable min 10ms reset pwm pwm enable vin, pwm power on power off pwm 2 to 5v min 0 s vin enable min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0 v vin 2 to 5v min 0 s pwm enable min 0 s 4.2 to 27v 2 to 5v 0 to 0.8v 0 to 0.8v 0v led ic timing sequence for pwm control turn-on figure 22. timing sequence3 led ic timing sequence for pwm control turn-off *other signal is input after a signal turned on. *other signal is input after a signal turned off. 15/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 how to activate please be careful about the following when being activated. - regulator (vdc) operates after enable=h. inside circui t operates after releasing uvlo. when ic boosts after releasing uvlo, soft start function operates. (ref er to figure 15, 9p). soft start circuit needs t 15 (more than 15s) as figure 25. shows. soft start operates for t soft time. please make h width of pwm more than 15s until soft start finishes. - please input pwm signal according to figure 26. after soft start finishes. figure 25. soft start example) time until soft start finishes at pwm frequency 25khz and pwm=h time16s according to soft start time typ4.3ms t soft = 16s ? 15s = 1s soft start time/ t soft /pwm frequency = 4300s / 1s /25khz = 4300 / 25khz = 172ms figure 26. input timing (after soft start) name unit min. typ. max. t1 power supply rising time s 100 - - t2 power supply-enable time s 0 - - t3 enable rising time s 0 - 100 t4 enable falling time s 0 - 100 t5 enable low width s 50 - - t6 power supply-pwm time s 0 - - t7 pwm rising time s 0 - 100 t8 pwm high width s 5 - - t9 pwm falling time s 0 - 100 t10 pwm low width s 5 - - t11 pwm frequency s 40 5000 10000 t12 enable (h)->pwm (h) time s 0 - - t13 enable (l)->pwm (l) time s 0 - - t14 pwm (l)->enable (l) time s 0 - - t15 pwm high width (while soft start) s 15 - - h operating voltage v 4.2 12 27 l non operating voltage v - - 4.2 l[v] vin vdc enable t1 h[v] t2 t3 t14 t6 t10 t11 t7 t9 t8 t4 t5 h[v] pwm t14 t3 a t light dimming of pwm terminal (after soft start finishes) vin vdc enabl e uvlo pwm soft start over current value increases.. t t soft t soft t soft 16/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 how to select the number of led strings of the current driver when the number of led strings of the current driver is reduc ed, the un-select can be set the matter that the unnecessary ch1 to 8 terminal is opened. when it uses with 6 lines and so on, it can correspond to it by becoming 2 unnecessary lines to open. when vout wake up, vout boost up until ovp voltage. once ic detect ovp, vout don?t boost up until ovp from next start up. to set pwm and enable to l, ic reset ch7, 8 status as figure 27. when vout wake up, ch8 (open terminal) and ch1 are selected as figure 28. figure 27. select the number of ch lines 1 figure 28. select the number of ch lines 2 (wake up) ch 1 ch 2 ch 3 ch 4 ch 5 ch 7 ch 6 ch 8 pwm enabl e vout ch1 to 6 ch7 to 8 ov p normal volta g e 0.8v(typ.) 0v 0v reset mask open ch1 curren t ch8 terminal ch8 curren t 20ma vo u t soft start: typ 4.3ms enable stable pwm ch1 terminal 0ma 0ma feedback terminal typ 0.8v over voltage protect signal ?unmask ter m in al s el e c t ( led open protect ) ch1 ch 8 normal condition o ver volta ge protect 10 0 s(ty p .) 17/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 start control (enable) and select led current driver (pwm) this ic can control the ic system by enable, and ic can power off compulsory by setting 0.8v or below. also, it powers on enable is at more than 2.0v. after it?s selected to enable=h, when it is selected at pwm=h, led current decided with iset resistance flow. next, when it is selected at pwm=l, led current stop to flow. enable pwm ic led current 0 0 off off 1 0 on off 0 1 off off 1 1 on current decided with iset led current setting range led current can set up normal current by resistance value (riset) connecting to iset voltage. setting of each led current is given as shown below. riset = 720/iledmax also, normal current setting range is 10ma to 30ma. led cu rrent becomes a leak current max 2a at off setting. iset normal current setting example riset led current 24k ? (e24) 30.0ma 30k ? (e24) 24.0ma 36k ? (e24) 20.0ma 43k ? (e24) 16.7ma 68k ? (e12) 10.6ma frequency setting range switching frequency can be set up by resistance value (rfset) connecting to fset port. setting of frequency is given as shown below. also, frequency setting range is 0.60mhz to 1.60mhz. fset frequency setting example rfset frequency 130k ? (e96) 0.57mhz 56k ? (e24) 1.25mhz 43k ? (e24) 1.59mhz max duty example frequency max duty[%] min typ max 0.57mhz - 96.0 - 1.25mhz 91.0 95.0 99.0 1.59mhz - 92.0 - min duty example frequency min duty[%] min typ max 1.25mhz - 20 - frequency [mhz] 1.25 56k ? 130 k ? fset[k ? ] 0.57 1.59 43 k ? 18/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 pwm dimming current driver pwm control is controlled by providing pwm signal to pwm port, as it is show in figure 29. the current set up with iset is chosen as the h section of pwm and the current is off as the l section. therefore, the average led current is increasing in proportion to duty cycle of pwm signal. this method that it lets internal circuit and dc/dc to work, because it becomes to switch the driver, the current tolerance is a few when the pwm brightness is adjusted, it makes it possible to brightness control until 5s (min 0.1% at 200hz). and, don't use for the brightness control, because effect of iset changeover is big under 1s on time and under 1s off time. typical pwm frequency is 100hz to 25khz. conditions 8serial 6parallel, led current=20ma/ch, vin=7v, ta=25 , output capacitor=2.2 f(50v/b3) analog dimming bd6142amuv control led current according analog input (abc terminal). for abc voltage = typ 0.733v, led current can set up normal current by resistance value (riset) connecting to iset voltage. to decrease abc voltage, led current decrease, and to increase abc voltage, led current increase. please set max led current to check led current setting range of p.17 please care that abc voltage of max led current is 0.733v abc input range is 0.05v to 0.9v(target). this dimming is effected by iset tolerance as follows. when you don?t use analog dimming, please set condenser to abc terminal. until the condenser of abc terminal is finished to charge, led current increase with that speed. the resister between 1.2v and abc terminal is 120.9k ? . please select the capacitor to care charge time. pwm led current coil current ic?s active current on off on off on off on figure 29. pwm sequence iset + - iset resistor driver abc 1.2v 0.733v dc input 120.9k ? 36k ? 180k iset + - iset resistor driver abc 1.2v 0.733v 120.9k ? 180k ? 36k ? figure 30. analog dimming application figure 31. pwm dimming application iled [ma] 20ma 0.733 v 0.9v abc[v] figure 32. iled vs abc voltage pwm vout led current vout pwm 400ns/div 10ma/div led current 40ns/div 10ma/div 19/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 coil selection the dc/dc is designed by more than 4.7h. when l value sets to a lower value, it is possibility t hat the specific sub-harmonic oscillation of current mode dc / dc will be happened. please do not let l value to 3.3h or below. and, l value increases, the phase margin of dc / dc becomes to zero. please enlarge the output capacitor value when you increase l value. please select lower dc resistance (dcr) type, efficiency still relies on the dcr of inductor. please estimate peak current of coil. peak current can be calculated as following. peak current calculation 20/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 output capacitor selection output capacitor smoothly keeps output voltage and supplies led current. output voltage consists of charge (fet on) and discharge (led current). so output voltage has output ripple voltage every fet switching. output ripple voltage is calculated as following. output ripple voltage - switching cycle = t - total led current = i led - switching on duty = d - output ripple voltage = v ripple - output capacitor = cout - output capacitor (real value) = c real - decreasing ratio of capacitor = c error c real = cout c error (capacitor value is decreased by bias, so) c real = i led d t / v ripple cout = i led d t / v ripple / c error (example 1) in case of, v in =12.0v, fsw = 1.2mhz, vout =32v, i led =120ma, cout = 8.8f, c error = 50% t = 1 / 1.2mhz d = 1 ? v in / vout = 1 ? 12/32 v ripple = i led d t / (coutc error ) = 120ma (1-12/32) / 1.2mhz / (8.8f0.5) = 14.2mv 0v 35v 50v output voltage capa [f] cout c real figure 33. bias characteristics of capacitor 21/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 the separations of the ic power supply and coil power supply this ic can work in separating the power source in both ic power supply and coil power supply. with this application, it can obtain that decrease of ic power consumption, and the applied voltage exceeds ic rating 27v. that application is shown in below figure 34. the higher voltage source is applied to the power source of coil that is connected from an adapter etc. next, the ic power supply is connected with a different coil power supply. under the conditions for inputting from 4.2v to 5.5v into ic vin, please follow the recommend design in figure 34. it connects vin terminal and vdc terminal together at icoutside. when the coil power supply is applied, it is no any problem even though ic power supply is the state of 0v. although ic power supply is set to 0v, pull-down resistance is arranged for the power off which cuts off the leak route from coil power supply in ic inside, the leak route is cut off. and, ther e is no power on-off sequence of coil power supply and ic power supply. separate vin and coil power supply connect vin and vdc terminals figure 34. application at the time of power supply isolation bd6142amuv ch1 ch 2 ch 3 ch 4 ch 5 ch 6 ch 7 ch 8 ovp 10 serial x 6 parallel (60pcs) 20ma abc lx lx 2.2f/50v fa ult vin 10h 10f 7v to 27v enable reset pwm 2.1v to vin co mp 1k ? iset 36k ? gnd pgnd pwm f pw m =100hz~25khz vdc pgnd 22 n f 2. 2m ? 68k ? vout 2.2f gnd pgnd fset 4.2v to 30v test 1nf 56 k ? bd6142amuv ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8 ov p 10 serial x 6 par allel (60pcs ) 20ma abc lx lx 2.2f/50v fault vin 10h 10f 4.2v to 5.5v enable reset pwm 2.1v to vin comp 1k ? iset 36k ? gnd pgnd pwm f pwm =100hz~25khz vdc pgnd 22n f 2.2m ? 68k ? vout 2.2f gnd pgnd fset 4.2v to 30v test 56k ? 1nf 22/30 bd6142amuv datasheet tsz02201-0g3g0c400340-1-2 03.dec.2012 rev.001 www.rohm.com ? 2011 rohm co., ltd. all rights reserved. tsz22111 ? 15 ? 001 layout in order to make the most of the performance of this ic, its pcb layout is very important. characteristics such as efficiency and ripple and the likes change greatly with layout patterns, which please note carefully. figure 35. schematic put input bypath capacitor cin (10 f) as close as possible between coill1 and pgnd pin. |
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