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1/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. led drivers for lcd backlights backlight led driver for small lcd panels (charge pump type) BD1204GWL description BD1204GWL is 3ch or 4ch parallel led driver for the portable instruments. this ic is equipped with an automatic transition charge pump and 16-step led drivers. hence this ic realizes high efficiency and high accuracy drive of leds. additionally, this ic can synchronize led drive with external pwm signal. this ic is best suited to turn on white leds that requ ire high-accuracy led brightness control. features 1) 3ch or 4ch parallel led driver is mounted 2) 16-step led current adjust function 3) led current matching is 5: 5% or less 4) driving control via a single -line digital control interface 5) automatic transition charge pump type dc/dc converter (1, 1.5, 2) 6) high efficiency achieved (maximum over 93%) 7) it transits for the most suitable power operating by t he led terminal processof the 4th light when 3 light driving 8) various protection functions such as output voltag e protection and thermal shutdown circuit are mounted. 9) the input external pwm is possible and the back light control interlocked with the motion picture is possible. 10) package: ucsp50l1 (thick 0.55mm max, pin pitch 0.4mm) csp14pin package absolute maximum ratings (ta=25 ) parameter symbol ratings unit power supply voltage vmax 7 v input voltage ( en , pwmin ) vdin gnd-0.3 ~ vbat+0.3 v power dissipation pd 840 mw operating temperature range topr -30 ~ +85 storage temperature range tstg -55 ~ +150 note 1) the measurement value whic h was mounted on the pcb by rohm. when a glass epoxy substrate (70mm 70mm 1.6mm) has been mount ed, this loss will decrease 6.72mw/ if ta is higher than or equal to 25 . operating conditions (ta = -30 ~ 85 ) parameter symbol limits unit operating power supply voltage vbat 2.7 ~ 5.5 v *this chip is not designed to protect itself against radioactive rays. *this material may be changed on its way to designing. *this material is not the official specification. no.10040eat07
technical note 2/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL electrical characteristics (unless otherwise noted, ta = +25 o c, vbat=3.6v) parameter symbol limits units conditions min. typ. max. current consumption quiescent current i q - 0.1 1 a en=0v current consumption1 i dd1 - 41.3 42.5 ma x 1.0 mode include led current (40ma) current consumption2 i dd2 - 82.6 83.9 ma x 2.0 mode include led current (40ma) charge pump oscillator frequency f osc 0.56 0.85 1.14 mhz current source led maximum current i led-max 18 20 22 ma vbat 3.0v led current accuracy i led-diff - - 10.0 % led current setting is 10.0ma, led terminal voltage is 1.0v led current matching i led-match - 0.5 5.0 % led current setting is 10.0ma, led terminal voltage is 1.0v led control voltage v led - 0.15 0.25 v minimum voltage from led1 to led4 pins logic control terminal low threshold voltage v il - - 0.4 v en , pwmin high threshold voltage v ih 1.4 - - v en , pwmin high level input current i ih - 0 1 a en = vbat, pwmin = vbat low level input current i il -1 0 - a en = 0v, pwmin = 0v minimum en high time t hi 0.05 - 100 s described in fig.5 minimum en low time t lo 0.3 - 100 s described in fig.5 en off timeout t off 1 - - ms described in fig.5 latch time t lat 1 - - ms described in fig.5 access available time tacc 1 - 5 ms described in fig.5
technical note 3/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL block diagram pin number 14pin fig. 1 block diagram pin configuration [bottom view] d led2 led1 vbat c1n c led3 en c1p bled4 index pwmin c2p a gnd iset vout c2n 1 2 3 4 fig. 2 pin configuration 1, 1.5, 2 charge pump over voltage protect osc tsd enable/ brightness control vout control charge pump mode control current dac gnd led1 led2 led3 en vbat vout c1n c1p c2n c2p 4 led4 det led4 pwmin iset
technical note 4/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL package outline (unit: mm) fig. 3 package dimension 2 p=0.43 14- 0.20.05 1.850.05 d 3 b 1pin mark s c 1 a a 0.05 0.55max b p=0.43 b 1.850.05 4 s 0.06 a ( 0.15)index post 0.3250.05 0.10.05 0.3250.05 lot no. 1204
technical note 5/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL pin descriptions pin no. terminal no. pin name in/out type function 1 d3 vbat - a power supply 2 c4 c1p in/out a flying capacitor pin positive (+) side 3 d4 c1n in/out b flying capa citor pin negative (-) side 4 b4 c2p in/out a flying capacitor pin positive (+) side 5 a4 c2n in/out b flying capa citor pin negative (-) side 6 a3 vout out a charge pump output 7 c2 en in c on/off and dimming control 8 d2 led1 out a led current driver output 1 9 d1 led2 out a led current driver output 2 10 c1 led3 out a led current driver output 3 11 b1 led4 out a led current driver output 4 12 b3 pwmin in c pwm control 13 a1 gnd - d gnd 14 a2 iset out b led standard current pin esd type fig. 4 pin esd type pad v bat type d pad gnd type c vbat pad gnd type b vbat pad gnd type a
technical note 6/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL t lo t off t lat t hi en n 0 0 led current setting 12 n (n ? 16) t acc n-1 t pulse t off en 1 0 0 led current setting t accmax en 16pulse 15pulse 14pulse t lat t acc t lat t lat 13pulse t lat 0.125ma 0.25ma 0.5ma 1ma led current off separate function description (1) led driver a) register access control protocol led current is controlled by only en terminal. it is possible to access the register inside of this chip by using the protocol below. accessing the registers with using this pr otocol operates led driver on/off and selecting the mode. moreover, max current can be outputted wi thout clock input to en terminal by holding h zone of fixed time after en terminal starting. < when setting current level > (notes) t accmin < t pulse < t accmax please input a pulse on this condition < when starting by max setup > fig.5 register access protocol fig.6 slope control example ( note ) ? in the case of n > 16, BD1204GWL selects the mode of n = 16. ? led current is changed by the pulse of en pin. be careful to noise of en signal. ? reset BD1204GWL when the set is unusual. (keep en=l over toff time.)
technical note 7/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL b) led current level the interface records rising edges of the en pin and decodes them into 16 different indicated in following table. data output current [ma] data output current [ma] 1 20.0 9 5.0 2 17.0 10 4.0 3 14.0 11 3.0 4 12.0 12 2.0 5 10.0 13 1.0 6 8.5 14 0.5 7 7.0 15 0.25 8 6.0 16 0.125 (riset=120 k ? ) moreover, led current can be set up with the resistance riset connected to iset terminal, and the maximum current is decided by the following formula. i ledmax [a] = 2.4/ r iset [k ? ] (typ) (2) charge pump a) description of operations pin voltage comparison takes place at vout control sect ion, and then vout generation ta kes place so that the led cathode voltage with the highest vf is set to 0.15v. a bo ost rate is changed automatically to a proper one at the charge pump mode control section so that operation can take place at possible low boost rate. in addition, when the vout output is short-circuited to g nd, the leak current is suppressed vi a the overcurrent protection function. b) soft start function BD1204GWL have a soft start function that prevents the rush current. soft start ordinal mode en/led* vout i led t off * en/led is an internal enable fig.7 soft start c) automatic boost rate change the boost rate automatically switches to the best mode. * (1 mode ? 1.5 mode) or (1.5 mode ? 2 mode) if a battery voltage drop occurs BD1204GWL cannot mainta in the led constant curr ent, and then mode transition begins. * (1.5 mode ? 1 mode) or (2 mode ? 1.5 mode) if a battery voltage rise occurs, vout and vbat detecti on are activated, and then mode transition begins. (3) uvlo (under voltage lock out) if the input voltage falls below 2.2v(typ.), BD1204GWL is shut down to prevent malfunction due to ultra-low voltage. (4) ovp (over voltage protection) this circuit protects this ic against damage when the c/p output voltage (vout) rises extremely for some external factors. (5) thermal shutdown (tsd) to protect this ic against thermal damage or heat-driven unc ontrolled operations, this circuit turns off the output if the chip temperature rises over 175oc. in addition, it turns on the output if the temperature returns to the normal temperature. because the built-in thermal protection circuit is intended to protect the ic itself, the thermal shutdown detection temperature must be set to below 175oc in thermal design.
technical note 8/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL (6) power sequence en signal must be released after vbat voltage enough rise up. prohibit the vbat rise up during en=?h?. v bat en fig.8 power sequence (7) pwm control pwm control by the external terminal (pwmin) is possible. it becomes pwm operation that used led cu rrent by a register setup as the base and is the best for the brightness compensation by external control. if the application wi th is not use pwm, pwmin pin must be short to vbat. fig.9 external pwm input solution it is possible to make it a pwmin input before en/led* is ?h?. a pwm drive becomes effective after the time of led current standup. when rising during pwm operation, as for the standup time of vout, only the rate of pwm duty becomes late. appearance may be influenced when extremely late frequency and extremely low duty are inputted. please secure over 120 s ?h? sections at the time of pwm pulse force. en/led* is an internal enable signal pwmin led current l compulsion off h normal operation en/led* vout pw min input led current in te rn a l s o ft-sta rt tim e non-pw m pw min input led current
technical note 9/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL application circuit example (4 light with pwm) fig.10 application circuit example 1 application circuit example (3 light with pwm) fig.11 application circuit example 2 1, 1.5, 2 charge pump over voltage protect osc tsd enable/ brightness control vout control charge pump mode control current dac gnd led1 led2 led3 en battery vbat vout c1n c1p c2n c2p c1=1 f c2=1 f cin =1 f cout =1 f 4 from cpu led4 det pwmin from lcm led4 iset 120k ? 1, 1.5, 2 charge pump over voltage protect osc tsd enable/ brightness control vout control charge pump mode control current dac gnd led1 led2 led3 en battery vbat vout c1n c1p c2n c2p c1=1 f c2=1 f cin =1 f cout =1 f 4 from cpu led4 det pwmin from lcm led4 iset 120k ?
technical note 10/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL application circuit example (4 light without pwm) fig.12 application circuit example 3 1, 1.5, 2 charge pump over voltage protect osc tsd enable/ brightness control vout control charge pump mode control current dac gnd led1 led2 led3 en battery vbat vout c1n c1p c2n c2p c1=1 f c2=1 f cin =1 f cout =1 f 4 from cpu led4 det pwmin led4 battery iset 120k ?
technical note 11/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL notes for use (1) absolute ma ximum ratings an excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can break down devices, thus making impossible to identify break ing mode such as a short circuit or an open circuit. if any special mode exceeding the absolute maximum ratings is assu med, consideration should be given to take physical safety measures including the use of fuses, etc. (2) power supply and ground line design pcb pattern to provide low impedance for the wiring between the power supply and t he ground lines. pay attention to the interference by common impedance of layout pattern when there are plural power supplies and ground lines. especially, when there are ground pattern for small signal and ground pattern for large current included the external circuits, please separate each ground pattern. furthermore, for all power supply pins to ics, mount a capacitor between the power supply and the ground pin. at the same time, in order to use a capacitor, thoroughly check to be sure the characteristics of the capacitor to be used present no prob lem including the occurrence of capacity dropout at a low temperature, thus determining the constant. (3) ground voltage make setting of the potential of the ground pin so that it will be maintain ed at the minimum in any operating state. furthermore, check to be sure no pins are at a potential lo wer than the ground voltage including an actual electric transient. (4) short circuit between pins and erroneous mounting in order to mount ics on a set pcb, pay thorough attention to the direction and offset of t he ics. erroneous mounting can break down the ics. furthermore, if a short circuit occurs due to foreign matters entering between pins or between the pin and the power supply or the groun d pin, the ics can break down. (5)operation in strong electromagnetic field be noted that using ics in the strong elec tromagnetic field can malfunction them. (6)input pins in terms of the construction of ic, parasitic elements are inev itably formed in relation to potential. the operation of the parasitic element can cause interference with circuit operation, thus resulting in a malfunct ion and then breakdown of the input pin. therefore, pay thorough attentio n not to handle the input pins, such as to apply to the input pins a voltage lower than the ground respectively, so that an y parasitic element will operate. furthe rmore, do not apply a voltage to the input pins when no power supply voltage is applied to the ic. in addition, even if the power supply voltage is applied, apply to the input pins a voltage lower than the power supply voltage or within the guaranteed value of electrical characteristics. (7) external capacitor in order to use a ceramic capacitor as the external capaci tor, determine the constant with consideration given to a degradation in the nominal capacitance due to dc bias and c hanges in the capacitance due to temperature, etc. (8)thermal shutdown circuit this lsi builds in a thermal shutdown circuit. when junction temperatures become detection temperature or higher, the thermal shutdown circuit operates and turns a switch off. t he thermal shutdown circuit, whic h is aimed at isolating the lsi from thermal runaway as much as possible, is not aim ed at the protection or guarantee of the lsi. ther efore, do not continuously use the lsi with this circuit operating or use the lsi assuming its operation. (9) thermal design perform thermal design in which there are adequate margins by taking into account the permissible dissipation (pd)in actual states of use. (10) about the pin for the test, the un-use pin prevent a problem from being in the pin for the test and the un-use pin under the state of actual use. please refer to a function manual and an application notebook. and, as for t he pin that doesn't specially have an explanation, ask our company person in charge. (11) about the rush current for ics with more than one power supply, it is possible that rush current may flow instantaneously due to the internal powering sequence and delays. therefore, give special consideration to power coupling capacitance, power wiring, width of ground wiring, and routing of wiring. (12) about this document this document is the design materials to design a set. so, the contents of the materials aren't always guaranteed. please design application by having fully examination and evaluation include the external elements.
technical note 12/12 www.rohm.com 2010.02 - rev.a ? 2010 rohm co., ltd. all rights reserved. BD1204GWL ordering part number b d 1 2 0 4 g w l - e 2 part no. part no. package gwl:ucsp50l1 packaging and forming specification e2: embossed tape and reel (unit : mm) ucsp50l1 (BD1204GWL) 1.850.05 1pin mark 1.850.05 0.55max 0.10.05 s 0.06 s 3 0.3250.05 2 (0.15)index post 4 c 1 0.3250.05 b a p=0.43 p=0.43 d 14- 0.2 0.05 a b ba 0.05 ? 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 left when you hold reel on the left hand and you pull out the tape on the right hand 3000pcs e2 () direction of feed reel 1pin
r1010 a www.rohm.com ? 2010 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 products. 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, redunda ncy, 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, aerospac e 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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