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| toshiba bicd digital integrated circuit silicon monolithic t b 6 2 7 3 2 f u toshiba t b 6 2 7 3 2 f u feature the TB62732FU is a led driver by the high efficiency step up type dc-dc converter that 2-4 serial white led can be turned on. this ic builds in the nchmos fet transistor to switch the coil, and builds in the function which derate the led current corresponding to the rise in temperature. and, the average led current can be set up easily by the resistance with the outside. this ic is the most suitable as a driver of the led liquid crysta back light of the pda, the cellular phone and the the handy terminal. characteristics *maximum output voltage vo =< 17v *the variable setup of the average led current value by the resistance with the outside. 18 ma (typ) @ r_sens = 2.7 ohms 20 ma (typ) @ r_sens = 2.4 ohms *supply electric power it is turned on to the 320 mw load. *compact package ssop6 - p - 0.95b ( sot23-6pin ) *the led current derating function is built in. the derating of led current vs set temperature, on the automatic operation. *high efficiency 80% of the efficiency. @ 2-3leds turn on. if=20ma (typ) ) ron=2.0 ohms (standard) @ vin = 3.0 - 5.5v the power mos transistor building in of low ron. *pin assignment (top view) note 1: be careful of handling because there is a terminal which is poor at esd in this product. the step up type dc-dc converter only for white led driver lighting weight: 0.016 g (typ) t b 6 2 7 3 2 f u ssop6-p-0.95b k gnd shdn a gnd vcc v company headquarters 3 northway lane north latham, new york 12110 toll free: 800.984.5337 fax: 518.785.4725 web: www.marktechopto.com | email: info@marktechopto.com california sales office: 950 south coast drive, suite 265 costa mesa, california 92626 toll free: 800.984.5337 fax: 714.850.9314 company headquarters 3 northway lane north latham, new york 12110 toll free: 800.984.5337 fax: 518.785.4725 web: www.marktechopto.com | email: info@marktechopto.com california sales office: 950 south coast drive, suite 265 costa mesa, california 92626 toll free: 800.984.5337 fax: 714.850.9314
toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) block diagram no name function explanation 1 k it is the connection terminal with cathode and if setup resistance of led. it is the feedback terminal of the charge voltage wave form for the led current control. 2, 5 gnd it is the ground terminal of the logic part. 3 shdn it is the enable terminal. it becomes the standby mode with "l", and the led is turned off. the lighting operation is given with "h". 4 vcc it is the input terminal of the operation voltage for the ic. the operating voltage is 3.0 to 5.5v. 6 a it is the switch terminal of the coil for the dc/dc converter. the switch is a nch mosfet transistor. this is low ron. 2 fig 1 : block diagram terminal explanation note 2 : connect all the gnd terminals to the ground electric potencial. k 0 - 0.12v osc r s q stb a i(sub) i(add) 1.0mhz vcc gnd shdn a 0.35 gnd ref buffer toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) characteristics symbol rating unit supply voltage vcc - 0.3 to + 6.0 v input voltage vin - 0.3 to vcc + 0.3 a(anode) terminal current io(a) + 380 ma a(anode) terminal voltage vo(a) - 0.3 to + 17 v power dissipation pd 0.41 ( not on pcb ) w 0.47 (on pcb) *note 3 saturation heat resistance rth(j-a)1 300 ( not on pcb ) degree/w rth(j-a)2 260 ( onpcb ) operation temperature topr - 40 to + 85 storage temperature tstg - 40 to + 150 degree maximum juction temperature tj 125 note 3 : when every time the ambient temperature gets over 25 degrees with 1 degree, the allowable loss must reduce 3.8mw/degree more than maximum rated value. ( when on pcb.) absolute maximum rating ( unless otherwised notice topr = 25 degree ) characeristics symbol test condition min typ max unit supply voltage vcc - 3.0 - 4.3 v shdn terminal h-level input voltage vih - vcc -0.5 - vcc v shdn terminal l-level input voltage vil - 0 - 0.5 shdn terminal "h"level input pulse width tpw shdn - 0.5 - - ms setup led current (mean) io maximum step up condition. vo (a) is change from 3v to 16v 5 - 20 ma recommended operation condition (unless otherwise notice topr = -40 to 85 degree) 3 toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) characteristics symbol test condition min typ max unit supply voltage vcc 3.0 - 5.5 v operation supply current icc(on) vcc = 3.6v - 0.9 ma stand-by supply current icc(shdn) shdn = 0 v - 0.5 1.2 ua shdn terminal current i_shdn shdn = vcc, built in pull-down resisance - 4.2 7 ua mos-tr on resistance ron io(a) <= 380 ma, detection resistance value is contained. - 2.0 2.5 ohms mos-tr switching frequency fosc 0.7 1.0 1.3 mhz a terminal voltage vo(a) 17 - - v a terminal current io(a) 320 350 380 ma a terminal leakage current ioz(a) - 0.5 1 ua set up led current (mean) io vcc = 3 - 4.3v, r_sens = 2.7 ohms, 19.6 ma led current vcc dependence dio l = 6.8uh, topr = 25 degree (note 4) +/-5 +/-10 % derating start ambient temperature tdel r_sens = 2.7 ohms, l = 10uh, vo = 16v (note 5) - 45 - degr ee electric characteristics ( unless otherwised notice, topr = -40 to 85 degree & vcc = 3.0 to 5.5 v) note 4 : the derating function carries out the measurement in ta= 25 degree not to work. the specifications don't contain the dispersion of the r_sens resistor. io has the possibility to be different from the specifications by the inductance value and the relations of the load. note 5 : it is a specifications guarantee by the design. 4 toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) basic operation the step up type dc/dc converter is applied, and the basic circuit of the TB62732FU adopts peak control of the current pulse. the internal mos transistor nmos is turned on in the fixed frequency fosc =1mhz, and the charge has the energy in the inductance. inductance electric current il turns off nmos when it reaches 80% of 1/1mhz when it increased from il = 0 and it reached il = ilpeak = 380 (ma, typ). the shot key diode is turned on, and il = ic2 flows, because the coil may keep il = ilpeak. after that, ic2 is decrease, and become il = 0. this operation is repeated, and ic2 is fully done as to the charge, and it becomes io, and flows to led. the details of a basic pulse to use for the current control are shown in fig 3. 5 t = 1/fosc, fosc = 1mhz(typ) muximum duty 80 % ilpeak= 380(ma, max) when fitness inductance il = il peak when un-fitness inductance fig 3 : the switching wave form of the inductance fig 2 : the application circuit (example) k a gnd 0 - 0.12v osc buffer r sq ref a 0.35 i(sub) i(add) 1.0 mhz r_sens il, ilpeak io ic2 nmos c2 6.8 uh vcc c1 shdn vin stb il becomes 0 in the time. il doesn't become 0 in the time. toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) 6 fig 4 : burst control wave form the stae of the peak current control the peak current control is repeat in the control the waveform which showed it in the fig 3. the current pulse of the fig 3 is a charging current on the output capacitor c2. it is supplied to led as a discharge current on the output side capacitor, and it through the r_sens to gnd. and, as for the charging voltage waveform of the output capacitor c2, it returns in the ic from the k terminal. the internal circuit which the k terminal should be input from controls the current pulses so that the average voltage value of the voltage wave form which it could get may become 53 mv (typ). the constant current is controlled as a result as an average electric current value. therefore, when r_sens = 2.7 ohm is connected, the average current value of (53 mv /2.7 ohms) = 19.6 ma can get it. this ic is designed for the purpose of supplying the power 320 mw (min). generally it is a step up inductance 6.8 uh to the load power 320 mw. and, when the load electric power is small, it can be done small for the inductance. as a condition about the led load between the generator terminal and the k terminal, please keep the condition in vin (vcc) < led vf total. there are no relations with the control of the ic, and led is always turned on. standby mode operation the shdn terminal set-up the normal operation and the standby operation. the lighting operation is possible in the "l" level in the stop (at the standby mode), the "h" level. still, consumption supply current in the standby mode is 1.2ua (max). a-terminal voltage a-terminal current (external inductor current) k-terminal voltage (waveform of current for cap. charge) maximum on pulse width = 85% i a( peak ) led vf switching frequency fosc = 1mhz it stabilizes it in the set io with lowering ia (peak). it stabilizes it in the set io with lowering ia (peak). toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) 7 the setup on the output side capacitor the c2 is upper 0.47(uf) above is recommended from the consideration to the if peak. the setup on the inductance the minimum inductance with the outside is calculated with the next formula. l(uh) = ((k*po)-vin min.*io)*(1/fosc min.)*2*(1/(ip min.*ip min.)) - - - form 2 each clause is as mentioned in the following. po (w) : output power (the electric energy which should be necessary the led load) po (w) = (vf led*if led)+(vf schottky*if led)+(r_sens*if led*if led) ( forward current of led is if led (ma) = setup currnet io (ma), forward voltage of led is vf led (v), forward voltage of schottky diode is vf schottky (v), setup resistance of output currnet is r_sens (ohms) ) vin min (v) : minimum input voltage(battely voltage) when there is a resistance element on the input voltage side, that one for the voltage descent is taken into consideration to the minimum input voltage. the input iin is estimated roughly in form 3. iin (ma) = vo / vin * if --- form 3 example, the voltage drop of 1(v) occurs when it becomes iin = 0.1(a) and has the line resistance of 1 (ohms). at this time, vin=3.1 (v) becomes minimum vin value because the minimum vcc specifications of spec is vcc=3.0 (v). io (a) : the average current value established with r_sens. show the fig-5 on next page. fosc(hz) : the switching frequency of the internal mos transistor. the specification of fosc(mhz) = 0.7 min, 1.0 typ and 1.3 max. ip (a) : peak current value to supply to the inductance. the specification of ip (ma) = 320 min, 350 typ, 380 max. for example, the following condition is substituted for the formula. it is supposed under condition. input voltage vin : vin=3.0-4.3(v), output side capacitance c2 : c2=0.47(uf) - - - c2 is ignored by the calculation. vf led = 16(v), schottly diode vf: vf schottky = 0.3(v), setup resistence r_sens : r_sens = 2.7(ohms), setup current io : io = 19.6(ma). l (uh) = ((16*0.0196+0.3*0.0196+2.7*0.0196*0.0196)- vin *0.0196)*(1/700e3)*2*(1/(0.32*0.32)) = 7.19(uh, vin = 3.0v) and 6.59 (uh,vin = 4.3v) therefore, 7.19(uh) in vcc=3.0v whose input voltage is low is chosen. it is sufficient by the above calculation on the standard condition. if the worst case is taken into consideration, the coil of about 1.1 times of the calculation is chosen. l(uh)=7.19(uh)*1.1 >= 7.90 (uh) capacitor c2 (uf) ripple current (ma) note 0.01 15-25 0.1 5-8 0.47 2-4 recommend 1 1-3 toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) 1 10 1.2 1.5 1.8 2 2.2 2.7 3.3 4.7 5.6 6.8 8.2 9.1 setup resistance r_sens(ohm) 0 5 10 15 20 25 30 35 setup current ?ho(ma) 4leds add 3leds range add 2leds range setup current io vs setup resistance r_sens (typical value. vcc=3.6v ta = 25 degree) choice of the r_sens the resistance r_sens (ohm) in the k terminal - gnd is of the outout current io for the setup. the average outout current io(ma) can be set up by a resistance value. average setup electric current io (ma) is estimated roughly in the following. io (ma) = 53(mv) / r_sens (ohm) for example, r_sens = 2.7 (ohm) becomes io = 19.6 (ma). the absolute value accuracy of the current is to take the +/-12 percent into consideration. (the accuracy of r_sens isn't contained.) when 320 (mw) is output, this ic recommends l=10 (uh). example, when the output power gets over 320 (mw), the setup current io has the possibility that io doesn't meet the set point. and, this ic can get the setup current io even if the output side capacitor c2 isn't connected. in this case, be careful in the rush current ifp (ma) to led because the led current becomes the pulse current of the maximum peak magnitude 380 (ma). shortening circuit board wiring by using the part whose reactance element is small as much as possible is recommended with the r_sens resistor. and, mounting it near here as much as possible is recommended with each part in application circuit as well. 8 fig 5 : the graph of the setup current io and the setup resistance r_sens toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) 9 about the current derating function as for the led current, generally the current derating recommended against the rise in the ambient temperature. the TB62732FU aims at turning on white led of the back light illuminant of the color lcd safely and efficiently, and builds in the current derating function which set temperature was presumed. this ic has the character which makes the current 100(%) in the case of tjs=45 (degree) and which makes the current 0(%) again in the case of tjs=100 (degree) corresponding to internal detection temperature tjs. when it is seen from set temperature ta (degree), the temperature that self-fever temperature tup (degree) in the operation was reduced from tjs = 45 (degree) becomes a starting temperature ts (degree). starting temperature ts (degree) = 45 (degree) - self-fever temperature tup (degree) --- form 4 therefore, the derating character functions as the figure 6, and shows internal detection temperature tjs and the rate of change of the outout current. self-fever temperature tup (degree) in the operation is calculated with the form 5. self-fever temperature tup (degree) ---- ceremony 5 = (p loss (w) - p parts(w))*rth(j-a) (degree/w) it is described in the following about each clause. dc resistance of the inductance : rdc(ohm), forward current of led : if led(a), total forward voltage of led : vf led(v), forward voltage : vf schottky(v), setup resistance : r_sens(ohm), power loss of lighting circuit : p loss(w)=(po/efficiency)-po(w), power loss of parts : p parts(w)=rdc*iin+vf schottky*if led+r_sens*if led*if led, saturation thermal resistance of package : rth(j-a) (degree/w) =< 260 - - - when on board, muximum output power : po(w) = vf led*io(a) input power : pi(w) = vin (v)*iin(a) efficiency : efficiency(%)=100*(po/pi) example : when the measurement of the lighting circuit tightened each following value. rdc=0.5(ohm), po=320(mw), iin=0.1(a), io=20(ma), r_sens=1.8(ohm), vf schottky=0.3(v), efficiency=70(%) in this case, self-fever temperature tup tup (degree)= ((0.32-(0.32*0.7))-(0.5*0.1+0.3*0.0196+2.7*0.0196*0.0196))*260 =10.16 (degree) start temperatue ts(degree)=45(degree)-10.16(degree)=33.4(degree) io is controlled as the fig 6 as a result within the recommendation current area of led. the saturation thermal resistance rth(j-a) = 260 (degree /w) is maximum value. they sometimes become the rth(j-a) = 210 - 260 (degree /w) by mounting. and, the individual difference is formed in the starting temperature with the character of the ic and the influence of the difference in the environment of the use. fig 6 : the derating function of the setup current 0 25 50 75 100 ts/tjs (degree) 0 20 40 60 80 100 120 rate of the outout current. the change of ts=34.4(degree) (20ma=100%) the recommendation current area of led (25ma conversion) the change by tjs toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) supply current in the operation icc (on) 3 3.5 4 4.5 5 5.5 vcc (v) 0 100 200 300 400 500 600 700 800 900 supply current (ua) 43 1 2 5 6 TB62732FU vcc suppy current in the shut-down mode icc(shdn) 3 3.5 4 4.5 5 5.5 vcc (v) 0 0.1 0.2 0.3 0.4 0.5 supply current (ua) 43 1 2 5 6 TB62732FU vcc 43 1 2 5 6 TB62732FU vcc switching frequency of inductanse 3 3.5 4 4.5 5 5.5 vcc (v) 300 320 340 360 380 400 switching frequency fosc 10 toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) application evaluation circuit example 1 (the evaluation result example by the small coil. : coil = ldr304612t-6r8) 6.8uh is the most suitable when serial 3-4led are turned on by if= 20m a. 4.7uh is recommended when serial 2led is turned on steadily in the range of vin>4.5v. 11 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 4led efficiency 4led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 3led efficiency 3led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 2led efficiency 2led if vin - efficiency/if l1 6.8uh s-di vin 3.2-4.2v c1 2.2uf c2 0.47uf on off r_sens 2.6 l1: tdk ldr304612t-6r8 s-di: toshiba 1ss404 20v/1a led: nichia nscw215t 2-4leds 0.01uf k a vcc shdn gnd gnd efficiency (%) ave efficiency(%) 2led 79.0-83.8 81.6 3led 75.1-80.9 78.3 4led 72.0-78.3 75.7 if (ma) vcc dependence (%) 2led 19.5-21.1 7.8 3led 19.5-20.5 4.9 4led 19.6-20.7 5.3 the efficiency of the vin=3.0-4.3v range the if of the vin=3.0-4.3v range toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) application evaluation circuit example 2 (the evaluation result example by the small coil. : coil = cxml321610-7r0) 6.8uh is the most suitable when serial 3-4led are turned on by if= 20m a. 4.7uh is recommended when serial 2led is turned on steadily in the range of vin>4.5v. 12 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 4led efficiency 4led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 3led efficiency 3led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 2led efficiency 2led if vin - efficiency/if l1 6.8uh s-di vin 3.2-4.2v c1 2.2uf c2 0.47uf on off r_sens 2.6 l1: sumitomo cxml321610-7r0 s-di: toshiba 1ss404 20v/1a led: nichia nscw215t 2-4leds 0.01uf k a vcc shdn gnd gnd efficiency (%) ave efficiency(%) 2led 78.2-84.1 81.3 3led 72.0-79.1 75.8 4led 66.9-71.1 74.6 if (ma) vcc dependence (%) 2led 19.8-21.6 8.1 3led 20.0-21.0 4.8 4led 20.4-21.5 4.9 the efficiency of the vin=3.0-4.3v range the if of the vin=3.0-4.3v range toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) application evaluation circuit example 3 (the evaluation result example by the small coil. : coil = 976as-6r8) 6.8uh is the most suitable when serial 3-4led are turned on by if= 20m a. 4.7uh is recommended when serial 2led is turned on steadily in the range of vin>4.5v. 13 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 4led efficiency 4led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 3led efficiency 3led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 2led efficiency 2led if vin - efficiency/if l1 6.8uh s-di vin 3.2-4.2v c1 2.2uf c2 0.47uf on off r_sens 2.6 l1: toko 976as-6r8 s-di: toshiba 1ss404 20v/1a led: nichia nscw215t 2-4leds 0.01uf k a vcc shdn gnd gnd efficiency (%) ave efficiency(%) 2led 79.7-84.4 82.3 3led 76.7-82.1 79.5 4led 73.1-79.7 74.0 if (ma) vcc dependence (%) 2led 19.4-21.1 8.1 3led 19.5-20.5 5.1 4led 19.6-20.7 5.3 the efficiency of the vin=3.0-4.3v range the if of the vin=3.0-4.3v range toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) application evaluation circuit example 4 (the evaluation result example by the small coil. : coil = cxld140-6r8) 6.8uh is the most suitable when serial 3-4led are turned on by if= 20m a. 4.7uh is recommended when serial 2led is turned on steadily in the range of vin>4.5v. 14 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 4led efficiency 4led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 3led efficiency 3led if vin - efficiency/if 3 3.2 3.4 3.6 3.8 4 4.2 vin (v) 15 20 25 led current if (ma) 65 70 75 80 85 efficiency (%) 2led efficiency 2led if vin - efficiency/if l1 6.8uh s-di vin 3.2-4.2v c1 2.2uf c2 0.47uf on off r_sens 2.6 l1: sumitomo cxld140-6r8 s-di: toshiba 1ss404 20v/1a led: nichia nscw215t 2-4leds 0.01uf k a vcc shdn gnd gnd efficiency (%) ave efficiency(%) 2led 80.3-84.9 82.9 3led 77.2-82.8 80.2 4led 74.1-80.4 77.6 if (ma) vcc dependence (%) 2led 19.4-21.0 7.6 3led 19.5-20.5 5.1 4led 19.6-20.7 5.3 the efficiency of the vin=3.0-4.3v range the if of the vin=3.0-4.3v range toshiba t b 6 2 7 3 2 f u 27, feb 2002 (ver.04) package 15 ssop6-p-0.95b 1.6 + 0.2 - 0.1 1.9 + 0.2 - 0.2 0.95 0.95 2.9 + 0.2 - 0.2 2.8 + 0.2 - 0.3 0.40 + 0.1 - 0.1 1.1 + 0.1 - 0.1 0.125 + 0.1 - 0.05 0~0.15 0.1 0.20 min 0.8 + 0.1 - 0.1 unit : mm |
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