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BD60A60NUX 1/22 www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. led drivers for lcd backlights white backlight led drivers for small to medium lcd panels (switching regulator type) bd60a00nux, BD60A60NUX description this ic is boost dc/dc converter that c an drive white led with constant curren t. more stabled white led lighting can be achieved by direct current connection without electric tole rance and high-speed response by current mode. moreover, separating ic power supply (2.7v~5.5v) and coil power supply (2.3v~20v) makes it possible to widen input range, which will be helpful to be applied to various kinds of applications . over voltage setting can be selected corresponding to the number of led lightings. bd60a00nux is for max 11 lightings, BD60A60NUX is for max 6 lightings. features 1) boost dc/dc converter 2) drive led 11 lightings (vout=3.6v1 1+0.7v=40.3v ) bd60a00nux 3) brightness control by outside pwm signal (pwm frequency =100hz~30khz, 25khz 1% dimming application) 4) brightness control by dc input 5) soft start function (1ms typ.) 6) over voltage protection 42v typ. ( bd60a00nux), 28vtyp.( BD60A60NUX) 7) sbd open protection and output short protection 8) over current protection 9) led terminal over voltage protection 10) uvlo 11) vson008x2030 package (2.0mm 3.0mm 0.6mm max) applications digital video cameras, digital single-lens reflexes, digital st ill cameras, digital photo fram es, personal navigations (pnd), mobile phones, smart phones, mid, pda, hand-held computers, mp3 players, gps, digital media players, etc. absolute maximum ratings parameter symbol ratings unit condition maximum applied voltage 1 vmax1 7 v vin, en, pwm, iset terminals maximum applied voltage 2 vmax2 45 v fb, sw, vout terminals bd60a00nux maximum applied voltage 2 vmax3 31 v fb, sw, vout terminals BD60A60NUX operating temperature range topr -40 ~ +85 storage temperature range tstg -55 ~ +150 power dissipation 1 pd1 2000 mw *1 *1 4 layer (rohm standard board) has been mounted. when it?s used by more than ta=25 , it?s reduced by 20mw/ ? c. recommended operating range (ta=-40 ~ +85 ) parameter symbol ratings unit conditions operating power supply voltage vin 2.7 ~ 5.5 * v vin terminal operating coil voltage vcoil 2.3 ~ 20 v coil voltage *when the operating supply voltage is over 4.61v for bd60a00nux, please refer the application p.17 no.11040eat42
technical note 2/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. electrical characteristics (unless otherwise specified, ta=25 , vin=3.6v) parameter symbol limits unit conditions min. typ. max. quiescent current iq - 0.1 1.0 a en=0v current consumption (no boost) iddnb - 1.5 3.0 ma en=2.8 v, pwm=0v current consumption (boost) iddb - 2.5 5.0. ma en=2.8 v, pwm=2.8 v [en, pwm terminal] low input voltage range vthl - - 0.5 v high input voltage range vthh 1.4 - - v pull down register rcnt 65 100 135 k ? [switching regulator] fb terminal control voltage fb 0.56 0.70 0.84 v switching frequency fsw - 600 - khz max duty duty 90 95 - % fb=0v sw transistor on resistor ronn - 0.5 - ? isw=80ma sw transistor leak current iqsw - 0.1 2.0 a en=0v [protection] over current limit icoil - 750 - ma *1 over voltage limit bd60a00nux ovp1 40 42 44 v detect voltage of vout terminal over voltage limit BD60A60NUX ovp2 26 28 30 v detect voltage of vout terminal over voltage limit hysteresis ovphy - 1 - v vout terminal leak current iqvout - 0.1 1.0 a en=0v shot key diode open protection sop - 0. 2 - v detect voltage of vout terminal led terminal over voltage protection ledovp 4.4 5.9 6.4 v pwm=2.8v detect voltage of low voltage uvlo - 2.2 - v vin falling edge [current driver] led maximum current ilmax - - 30 ma vin=4v, cout=1f led current accuracy ila ccu - - 3.0 % iled=20ma led current limit ilocp - 0 0.1 ma current limit value at iset resistor 1k ? setting led leak current iqled - 0.1 2.0 a en=0v iset terminal voltage iset - 0.6 - v *1 this parameter is tested with dc measurement.
technical note 3/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. block diagram and application fig.1 block diagram and application ? pin assignment table pin no. pin name in/out f unction terminal diagram 1 en in enable control b 2 vin in battery input c 3 pwm in pwm input b 4 iset in led current setting terminal a 5 fb in feedback voltage input b 6 vout in over voltage protection input b 7 gnd - gnd c 8 sw out switching terminal b terminal diagram fig.2 terminal diagram gnd c vin gnd pin b gnd pin a vin l1 10 h + + - osc control + - s q r tsd sw en gnd pwmcomp erramp fb vin th erma l shutdown c urrent sense over current protect cbat 4.7 f cout 2.2. f coil power 2.3v to 20 v d1 q1 vout + - over & under voltage protect cin 1 f 11 leds pwm pwm control ic power 2.7v to 5.5v current driver iset uvlo enable control
technical note 4/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. main characteristics examples 1) efficiency BD60A60NUX led 6series, coil : vlf302512mt-100m bd60a00nux led 10series, coil : vlf302512mt-100m coil : vlf302512mt-100m
technical note 5/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. ic power=5.0v, coil power=4v to 16v ? bd60a00nux ic power=5.0v, coil power=2.7v to 20v, led 8serial, led current =25ma, coil 1094as-10m(toko), sbd rb060m-60tr(rohm) ? BD60A60NUX ic power=5.0v, coil power=2.7v to 20v, led 6serial, led current =25ma, coil 1094as-10m(toko), sbd rb521a-40tr(rohm) bd60a00nux vcoil vs efficiency vin=5vta=25 led 8(26v) coil 1094as-10m(toko) sbd rb060m-60tr(rohm) l edO2 5 ma pwm=100% eff1=(vout*iled)/(vcoil*icoil)*100 eff2=(vout*iled)/(vcoil*icoil+vin+ivin)*100 70 75 80 85 90 95 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 vcoil (v) efficiency (%) eff1 eff2 bd60a60 vcoil vs efficiency vin=5vta=25 led 6(20v) coil 1094as-10m(toko) sbd rb521s-40(rohm) for bd60a60 ledO25ma pwm=100% eff=(vout*iled)/(vcoil*icoil+vini*vin)*100 70 75 80 85 90 95 234567891011121314 vcoil (v) efficiency (%)
technical note 6/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. pwm 20khz dut y 50% vout led current pwm vout led current pwm pwm 20khz dut y 1% 100mv/div 100mv/div 40s/div 200ns/div
technical note 7/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. ? bd60a00nux pwm duty ? led current ic power=5.0v, led 8serial, led current =25ma, pwm frequency = 20khz, ta=25deg coil 1094as-10m(toko), sbd rb060m-60tr(rohm) bd60a00nux vcoil vs efficiency vin=5vta=25 led 8 (26v) coil 1094as-10m(toko) sbd rb060m-60tr(rohm) led current 25ma pwm frequency 20khz 0.01 0.10 1.00 10.00 100.00 0.1 1.0 10.0 100.0 pwm duty (%) led current (ma) possible to duty 0.4% at pwm=20khz 0.4%
technical note 8/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. functional descriptions 1) pwm current mode dc/dc converter this ic keeps output voltage invariably by setting pwm duty to make fb terminal 0.7v when the power is on. as for the inputs of the pwm comparator as the f eature 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 sub harmonic oscillatio n. this output controls internal nch tr via the rs latch. in the period where internal nch tr gate is on, energy is accumulated in the ex ternal 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) soft start this ic has soft start function, which prevents rush current at turning on. after en and pwm are changed l ? h, soft start becomes effective within 1ms. soft start doesn't become effective even if enable is changed l ? h, after that. by changing en and pwm l ? h, soft start can become effective. since a soft start function stops working at the time of following pwm=h when en=h is held with pwm=l after en=h should input a pwm signal within 10ms. pwm off on on off off off on off off en soft star t soft star t rese t reset reset soft start time finish pwm en within 10ms fig.3 soft start
technical note 9/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. protection ? over voltage protection at such an error of output open as t he output dc/dc and the led is not connected to ic, t he dc/dc boosts too much and the vout terminal exceeds the absolute maximum ratings , and may destruct the ic. therefore, when the vout becomes sensing voltage or higher, the over voltage limit pr otection works, turns off the switching tr, dc/dc will be stopped, and the output voltage goes down sl owly. when output voltage becomes be low the hysteresis voltage of over voltage protection, a boost function works and out put voltage reaches detection voltage again. this operation is repeated unless the abnor malities in application are recovered. ? schottky diode open protection in the case of external sbd is not connecte d to ic, or vout is shorted to gnd, t he coil or internal tr may be destructed. therefore, at such an error as vout becoming 0.2v 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-activa tion, 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 175 ? c or higher, and the ic changes from activation into non-activation. ? over current protection over current flows the current detection re sistor that is connected to between in ternal switching transistor source and gnd. current sense voltage turns more than detection voltage, over current protec tion is operating and it is prevented from flowing more than detection current by reduci ng on duty of switching tr without stopping boost. as over current detector of this ic is detected peak curren t, current more than over current setting value does not flow. < the estimate of the current value which need for the normal operation> as over current detector of this ic is detected the peak curr ent, it has to estimate peak cu rrent to flow to the coil by operating condition. in case of, switching frequency = fsw typ=0.6mhz supply voltage of coil = vin inductance value of coil = l output voltage = vout total led current = iout average current of coil = iave peak current of coil = ipeak efficiency = eff on time of switching transistor = ton ipeak = (vin / l) (1 / fsw) (1-(vin / vout)) iave=(vout iout / vin) / eff ton=(iave (1-vin/vout) (1/fsw) (l/vin) 2) 1/2 as peak current varies according to whether there is the direct current superposed, the next is decided. (1-vin/vout) (1/fsw) < ton ? peak current = ipeak /2 + iave (continuous mode ccm) (1-vin/vout) (1/fsw) > ton ? peak current = (vin / l)ton (discontinuous mode dcm) (example 1) in case of, vin=6.0v, l=10h, fsw=0.6mhz , vout=32.5v, iout=25ma, current =85% ipeak = (6.0v / 10h) (1 / 0.6mhz) (1-(6.0v / 32.5v)) =0.82 a iave = (32.5v 25ma / 6.0v) / 85% = 0.16a ton = (0.16a (1-6.0v / 32.5v) (1 / 0.75mhz) (10h /6.0v) 2) 1/2 = 0.85s (1- vin/vout) (1/fsw)=1.36s > ton peak current = (6.0v / 10h)0.85s =0.51a + - sw
technical note 10/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. ? led terminal over voltage protection when fb terminal becomes higher than 5.9v(typ), ic senses the situation trouble after 100us and then stops constant current driver and dc/dc. ther efore ic becomes never heated, even if output and fb are both shorted. moreover, if fb terminal becomes lower than 5.9v(typ), ic senses no rmal condition and activates constant current driver. ? prevention of led terminal over voltage protection malfunction as the below diagrams show, voltage drop of fb terminal becomes slow when pwm operates by connecting capacitor on a parallel with led and decreasing led current. at that time , led terminal voltage protection works after condition of fb terminal > 5.9v keeps more than 100us. led terminal voltage pr otection might stop current driver and dc/dc and also turns off leds, so that please set up coil selection and led cu rrent setting less than 100us until fb terminal < 5.9v. ? low voltage detect protection (uvlo) supply voltage(vin) becomes lower than low voltage detect voltage 2.2v(typ), ic stop s dc/dc and constant current driver. moreover, this function can be off by boosting supply voltage up to more than hysteresis voltage. dc/dc current driver vin reset 2.20 v 5% 0v a ctive a ctive 2.32 v current driver fb reset 5.9 v 0v a ctive a ctive dc/dc a ctive a ctive a ctive fb vou t current driver fb reset 5.9 v a ctive dc/dc a ctive 100us reset reset reset pwm l h en l h
technical note 11/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. operating of the application deficiency 1) when 1 led or 1string open during the operating since fb terminal is set to 0v when set to open, output b oosts up to the over voltage protection voltage. when over voltage is detected, the boosti ng operation stops and then output voltage goes down slowly. later, if output voltage becomes less than hysteresis of over cu rrent protection, output voltage keeps boos ting up to over voltage protection voltage again. fig. 8 led open detect 2) when led short-circuited in the plural even if one led short-circuits during boos t operation, it usually passes along le d and it is turned on. by making led shorted, fb terminal voltage increases by led vf. t herefore output voltage becomes lower by led vf, and the condition turns to be normal. fig. 9 one led shorted fig.10 fb terminal ? vout terminal shorted fb fb output vout fb voltage led connection normal open led current 20ma 0ma hysteresis voltage 0.7v+ vf of led f b vou t led curren t 20ma 0.7v led short vf of led vf of led fb vou t f b vou t led curren t 20ma 0.7v led short vin 5.9v 0.1ma 100us
technical note 12/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. 3) when schottky diode(sbd) remove in the situation that connection is opened and also dc/dc is activated, sw terminal voltage becomes more than rated voltage due to a lack of parts that c an accept the current accumulated inside the coil. consequently ic might be destroyed. to prevent the ic destruction, sbd open protecti on is functioned. sw terminal is never destroyed as boosting operation is stopped after vout terminal detects less than 0.2v. 4) when resistance linked to an iset terminal short-circuits since resistor connected to iset terminal becomes 0 , led current setting value becomes more than rating. in order to avoid this trouble, this ic has led current limit protection. by using this function, setti ng current of rating current driver becomes 0ma, and the current flow of led is almost same as leak current. control signal input timing when input control signals such as enable and pwm without completing the standup of supply voltage (vin), be careful of the following points. input each control signal after vin exceeds 2.2v and uvlo is off. when input enable and pwm, the standup time should be plac ed as min.100s from 2.2v to stable voltage for vin. since a soft start function stops working at the time of following pwm=h when en=h is held with pwm=l. after en=h should input a pwm signal within 10ms. start control (en) and select led current driver (pwm) this ic can control the ic system by en terminal and also tu rns off compulsorily by setting ?l? level input voltage 0.4v or below. it also powers on when en becomes more than ?h? level in put voltage 1.4v. in the case of en=h, led current fixed by iset resistor with pwm=h flows. when it is selected at pwm=l, led current stop to flow. en pwm ic led current l l off off h l on off l h off off h h on current fixed by iset led current setting range led current sets up normal current by resi ster (riset) connected to iset voltage. each setting current is shown as below. normal current = 600/riset [a] normal current setting range is 10ma~30ma, and also led current at off setting is max 2a of leak current. iset normal current setting example riset led current 20.0k ? (e96) 30.0ma 24.0k ? (e24) 25.0ma 30.0k ? (e24) 20.0ma 56.0k ? (e24) 10.7ma vin 2.2v en min. 100 s pwm dc/dc vout fig.11 control signal input timing vin en min. 10 ms pwm dc/dc vout
technical note 13/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. brightness control there are two dimming method available; the first method is analog dimming that applies analog voltage to iset terminal, and the second method is digital dimming that inputs pwm to pwm terminal. since each method has the different merits, please choose a suitable method for the application of use. 1) current driver pwm control is controlled by pr oviding pwm signal to pwm, as it is shown fig.12. the current set up with iset is chosen as the h section of pwm and the current is off as t he l section. therefore, the average led current increases in proportion to duty cycle of pwm signal. this method that internal circuit and dc/dc work, because it becomes to switch the driver, the current tolerance is a few when the pwm brightness is adjusted, so it makes it possible to brightness control until 0.4s (mi n1% at 25khz). and, don't use for the brightness control, because effect of iset changeover is big under 0.4s on time and under 3s off time. typical pwm frequency is 100hz~25khz. 2) analog dimming can be operated by applying voltage to iset terminal via resistor as the below figure shows. iset terminal voltage works to become 0.6v regardless of the connected resistor. led current increases iset terminal current 600 times, so that led current can be minimized by decreasing flow current into iset terminal using external dc input led current = 1000 x 0.6v 470k ? + 22k ? 1000 0.6v - dac output pwm led current coil current ic?s active current on off on off on off on fig.12 pwm sequence sw vin cin 4.7 f r1 24k ? cout 2.2 f 25ma vin 2.7v to 4.6 v vout fb l1 10 h iset gnd en pwm reset pwm input 0 5 10 15 20 25 30 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 dc voltage [v] led current [ma] 0 5 10 15 20 25 30 0 20406080100 pwm hi duty [%] led current [ma] sw vin cin 4.7 f r1 470k ? cout 2.2 f vin 2.7v to 4.6v vout fb l1 10 h iset gnd en pwm led on/off reset dc r2 22k ?
technical note 14/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. 3) the brightness control to set large current over ic max setting current is made by giving dc control voltage to vfb pin of ic via a series resistor as shown in under figure. led luminance (current) changed by giving dc voltage to vfb directly. dc voltage is given from filtered one of da c signal, or pwm signal shown in under figure. led current (iled) is next expression. iled = [[(fb-dc) / r1] * r2 + fb ] / rfb sw vin cin 4.7 f cout 2.2 f vin 2.7v to 4.6v vout fb l1 10 h iset gnd en pwm reset dc rfb 6.49 ? r2 6.8k ? 3s7p r1 22k ? sw vin cin 4.7 f cout 2.2 f vin 2.7v to 4.6v vout fb l1 10 h iset gnd en pwm reset pwm 5 ? 33k ? 3s7p 47k ? 100k ? 47nf 0 - 3.3v BD60A60NUX 3ledx7pararel iled tota l ( ma ) dc (v)
technical note 15/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. the 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. output capacitor selection output capacitor smoothly keeps output voltage and supplies led current. if led current is set more than 20ma with vcoil=2.3v 5.5v, please make output capaci tor more than 2.2f. otherwise phase margin of dc/dc decreases and might oscillate. 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 = c out - output capacitor (real value) = c real - decreasing ratio of capacitor = c error c real = c out c error (capacitor value is decreased by bias, so) c real = i led (1-d) t / v ripple c out = i led (1-d) t / v ripple / c error (example 1) in case of, v in =5.0v, fsw = 0.6mhz, v out =32.5v, i led =20ma, c out = 2.2f, c error = 50% t = 1 / 0.6mhz d = 1 ? v in / v out = 1 ? 5/32.5 v ripple = i led (1-d) t / (c out c error ) = 20ma (5/32.5) (1 / 0.6mhz) / (2.2f0.5) = 4.7mv led selection please select led vf that input voltage is smaller than output voltage (vout). 0v 35v 50v output voltage capa [f] c out c real
technical note 16/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. the separation 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 5.5v. that application is shown in below fig.14. the coil power suppl y is connected to high voltage source applied from adapters. then the ic power supply is connected to the power supply that should be different fr om the coil power supply. fig.14 application at the time of power supply separation fig.15 application at the ti me of power supply common the number of available leds by each power supply voltage condition sw vin cin 1 f r1 24k ? cout 2.2 f 25ma coil power 2.3v to 20v vout fb l1 10 h iset gnd en pwm reset pwm input ic power 2.7v to 4.6 v step down dc/dc 2,3cell battery ccoil 4.7 f sw vin cin 4.7 f r1 24 k ? cout 2.2 f 25ma vout fb l1 10 h iset gnd en pwm reset pwm input ic power 2.3v to 4.6 v cell battery dimmingled current setting25ma) 2.7v 3v v 5v 6v 7v 8v 9v 10v 11v 12v 13v 14v 15v 16v 17v 18v 19v 20v 2 cscscscs 3 cs cs cs cs s s 4 cs cs cs cs s s s s s 5 cs cs cs cs s s s s s s s 6 cs cs cs cs s s s s s s s s s 7 cs cs cs cs s s s s s s s s s s s 8 cscscscssssssssss sss 9 cscscscsssssssssssssss 10 cscscscssssssssssssssss c???vcoil-vin common power supply s???vcoil-vin separated power supply ???no use due to led terminal over voltage protection vin leds 3
technical note 17/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. about the order of a power supply injection at the time of power supply separation even if the ic power supply is 0v, leak channel is blocked as pull down resistor for power off is placed inside the ic. the resistor intercepts leak channel from coil power supply. additionally, there is no order for standing up and down of coil and ic power supply. ? at the time of starting it doesn?t matter whether coil power or ic power becomes activated first. ? at the time of power supply off please turn off after make en terminal ?l?. if power supply voltage of coil power becomes low, coil current increases due to high boosting, which leads to over current limit. in order to avoid this state, before turning off a power supply it is necessary to su rely set en to l. input voltage 5v bd60a00nux the gnd noise become big by impedance of pcb boards, so t hat wake up characteristics might become unstable. to select input voltage to 5v(input voltage 4.61v ove r), we recommend under application to insert 4.7 between input voltage line and vin terminal sw vin cin 4.7 f riset 24 k ? cout 2.2 f 25ma vin 2.7v to 5.5v vout fb l1 10 h iset gnd en pwm reset pwm input 4.7 ? ic power en pwm vout coil power free
technical note 18/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. pcb layout in order to make the most of the performance of this ic, its pc b layout is very important. characteristics such as efficiency and ripple and the likes change greatly with pcb layout, which please note carefully connect input capacitor cin (1 f) as close as possible between coil l1 and gnd. connect schottky barrier diode sbd as close as possible between coils l1and sw pin. connect output capacitor cout between cathode of sbd and gnd. make both gnd sides of cin and cout as close as possible. > connect led current setting resistor riset(24k ) as close as possible between iset pin and gnd. there is possibility to oscillate when capacity is added to iset terminal, so pay attention that capacity isn?t added. pad is used for improving the efficiency of ic heat radiation. solder pad to gnd pin. moreover, connect ground plane of board using via as shown in the patterns of next page. the efficiency of heat radiation improves according to the area of ground plane. when those pins are not connec ted directly near the chip, influence is gi ve to the performance of bd60a00nux, and may limit the current drive performance. as for the wire to the inductor, make its resistance component small so as to reduce electric power consumption a nd increase the entire efficiency. the pcb layout in consideration of these is shown in the next page. sw vin cin 4.7 f riset 24k ? cout 2.2 f 25ma vin 2.7v to 4.6v vout fb l1 10 h iset gnd en pwm reset pwm input
technical note 19/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. recommended pcb layout
technical note 20/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. selection of external parts recommended external parts are as shown below. when to use other parts than these, se lect the following equivalent parts. l1: this coil is for boosting. recommended capacity value is 10uh. please use the coil with adequate direct current capacity and also low direct current resistor. value manufacturer product number size dc current (ma) dcr ( ? ) vertical horizontal height 10h tdk vlf4012at-100mr79 4.0 3.8 1.2 800 0.30 10h tdk vlf302512mt-100m 3. 0 2.5 1.2 690 0.25 10h toko 1094as-100m 3.5 3.7 1.2 760 0.18 10h toko 1229as-h-100m 3.5 3.7 1.2 750 0.24 cin: this is bypath capacitor for power supply, which removes power supply noise occurred instantly and provides stable power supply for ic. in order to obtain better quality, please use low esr products such as ceramic capacitors. recommended capacity value is more than 1f. c0: this is output smoothing capacitor. recommended capacity value is 2.2f. when choosing capacitors such as cin and c0, please be careful of pressure. the base line of pressure is about 2 times of actual applying voltage. if pressure margin decreases, it might be happened that capacity value becomes almost a half of nominal value. value pressur e manufactur e product number size vertical horizontal height [ cin : power supply voltage capacitor] 1.0f 10v. murata grm185b 31a105 1.6. 0.8. 0.5. [ c0 : output capacitor ] 1.0f 50v murata grm 31mb31h105 3.2 1.6 1.15 2.2f 50v murata grm31cb31h225 3.2 1.6 1.6 r1: led current i led should be decided when activated. value tolerance manufacturer product number size i led (ma) vertical horizontal height [ r1 : resistor used for deciding led current] 20k ? 0.5% rohm mcr03pzpzd 2002 1.6 0.8 0.45 30 24k ? 0.5% rohm mcr03pzpzd 2402 1.6 0.8 0.45 25 30k ? 0.5% rohm mcr03pzpzd 3002 1.6 0.8 0.45 20 56k ? 0.5% rohm mcr03pzpzd 5602 1.6 0.8 0.45 10.7 d1: this schottky diode (sbd) is for output re ctification. in order to obtain higher switching efficiency, please use low vf, l ow reverse leak, and high current capacity. pressure manufacturer product number size vertical horizontal height 60v rohm rb160m-60 3.5 1.6 0.8 40v rohm rb521s-40 1.6 0.8 0.6 60v rohm rb060m-60 3.5 1.6 0.8
technical note 21/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. cautions on use (1) absolute maximum ratings an excess in the absolute maximum ratings, such as supply voltage (vin), temperature r ange of operating conditions (topr), etc., can break down dev ices, thus making impossible to identify breaking mode such as a short circuit or an open circuit. if any special mode exceeding the absolute maxi mum ratings is assumed, consideration should be given to take physical safety measures including the use of fuses, etc. (2) operating conditions these conditions represent a range within which characteri stics can be provided approx imately as expected. the electrical characteristics are guaranteed under the conditions of each parameter. (3) reverse connection of power supply connector the reverse connection of power supply connector can br eak down ics. take protec tive measures against the breakdown due to the reverse connection, such as mounting an external diode between the power supply and the ic?s power supply terminal. (4) power supply line design pcb pattern to provide low impedance for the wiring between the power supply and the gnd lines. furthermore, for all power supply terminals to ics, mount a capacitor between the power supply and the gnd terminal. at the same time, in order to use an electrolytic capacito r, thoroughly check to be sure the characteristics of the capacitor to be used present no problem including the occu rrence of capacity dropout at a low temperature, thus determining the constant. (5) gnd voltage make setting of the potential of the gnd terminal so that it will be maintained at the minimum in any operating state. furthermore, check to be sure no terminals are at a potentia l lower than the gnd voltage including an actual electric transient. (6) short circuit between terminals and erroneous mounting in order to mount ics on a set pcb, pay thorough attention to the direction and offset of the ics. erroneous mounting can break down the ics. furthermore, if a short circuit occurs due to foreign matters entering between terminals or between the terminal and the power supply or the gnd terminal, the ics can break down. (7) operation in strong electromagnetic field be noted that using ics in the strong elec tromagnetic field can malfunction them. (8) inspection with set pcb on the inspection with the set pcb, if a capacitor is connect ed to a low-impedance ic terminal, the ic can suffer stress. therefore, be sure to discharge from t he set pcb by each process. furthermore, in order to mount or dismount the set pcb to/from the jig for the inspection process, be sure to turn off the power supply and then mount the set pcb to the jig. after the completion of the inspection, be sure to tu rn off the power supply and then dismount it from the jig. in addition, for protection against static electricity, establis h a ground for the assembly process and pay thorough attention to the transportation and t he storage of the set pcb. (9) input terminals in terms of the construction of ic, parasitic elements are in evitably formed in relation to potential. the operation of the parasitic element can cause interference with circuit operati on, thus resulting in a malf unction and then breakdown of the input terminal. therefore, pay thorou gh attention not to handle the input te rminals, such as to apply to the input terminals a voltage lower than the gnd respectively, so t hat any parasitic element wi ll operate. furthermore, do not apply a voltage to the input terminals when no power supply voltage is applied to the ic. in addition, even if the power supply voltage is applied, apply to the input terminals a voltage lower than the power supply voltage or within the guaranteed value of electrical characteristics. (10) ground wiring pattern if small-signal gnd and large-current gnd are provided, it will be recommended to separate the large-current gnd pattern from the small-signal gnd pattern and establish a si ngle ground at the reference poi nt of the set pcb so that resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal gnd. pay att ention not to cause fluctuations in the gnd wiring pattern of external parts as well. (11) external capacitor in order to use a ceramic capacitor as the external capacitor, determine the c onstant with consideration given to a degradation in the nominal capacitance due to dc bias and c hanges in the capacitance due to temperature, etc. (12) thermal shutdown circuit (tsd) when junction temperatures become 175 (typ) or higher, the thermal shutdown circuit operates and turns a switch off. the thermal shutdown circuit, which is aimed at isolat ing the lsi from thermal runaway as much as possible, is not aimed at the protection or guarantee of the lsi. therefor e, do not continuously use the lsi with this circuit operating or use the lsi assuming its operation. (13) thermal design perform thermal design in which there ar e adequate margins by taking into account the permissible dissipation (pd) in actual states of use. (14) selection of coil select the low dcr inductors to decrease power loss for dc/dc converter.
technical note 22/22 bd60a00nux, BD60A60NUX www.rohm.com 2011.12 - rev. a ? 2011 rohm co., ltd. all rights reserved. ordering part number b d 6 0 a 0 0 n u x - t r rohm t yp e name part no. bd60a00:60a00 bd60a60:60a60 package nux: vson008x2030 packaging and forming specification tr: embossed tape and reel ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tape quantity direction of feed the direction is the 1pin of product is at the upper right when you hold reel on the left hand and you pull out the tape on the right hand 4000pcs tr () direction of feed reel 1pin (unit : mm) vson008x2030 5 1 8 4 1.4 0.1 0.25 1.5 0.1 0.5 0.3 0.1 0.25 +0.05 ? 0.04 c0.25 0.6max (0.12) 0.02 +0.03 ? 0.02 3.0 0.1 2.0 0.1 1pin mark 0.08 s s
r1120 a www.rohm.com ? 2011 rohm co., ltd. all rights reserved. notice rohm customer support system http://www.rohm.com/contact/ thank you for your accessing to rohm product informations. more detail product informations and catalogs are available, please contact us. notes no copying or reproduction of this document, in part or in whole, is permitted without the consent of rohm co.,ltd. the content specified herein is subject to change for improvement without notice. the content specified herein is for the purpose of introducing rohm's products (hereinafter "products"). if you wish to use any such product, please be sure to refer to the specifications, which can be obtained from rohm upon request. examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the products. the peripheral conditions must be taken into account when designing circuits for mass production. great care was taken in ensuring the accuracy of the information specified in this document. however, should you incur any damage arising from any inaccuracy or misprint of such information, rohm shall bear no responsibility for such damage. the technical information specified herein is intended only to show the typical functions of and examples of application circuits for the produc ts. rohm does not grant you, explicitly or implicitly, any license to use or exercise intellectual property or other rights held by rohm and other parties. rohm shall bear no responsibility whatsoever for any dispute arising from the use of such technical information. the products specified in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, office-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specified in this document are not designed to be radiation tolerant. while rohm always makes efforts to enhance the quality and reliability of its products, a product may fail or malfunction for a variety of reasons. please be sure to implement in your equipment using the products safety measures to guard against the possibility of physical injury, fire or any other damage caused in the event of the failure of any product, such as derating, redundancy, fire control and fail-safe designs. rohm shall bear no responsibility whatsoever for your use of any product outside of the prescribed scope or not in accordance with the instruction manual. the products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel- controller or other safety device). rohm shall bear no responsibility in any way for use of any of the products for the above special purposes. if a product is intended to be used for any such special purpose, please contact a rohm sales representative before purchasing. if you intend to export or ship overseas any product or technology specified herein that may be controlled under the foreign exchange and the foreign trade law, you will be required to obtain a license or permit under the law.

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