IS31BL3231 integrated silicon solution, inc. ? www.issi.com 1 rev. a, 01/03/2011 flash led driver january 2012 general description the IS31BL3231 is a current-regulated charge pump and ideal for powering high brightness leds for camera flash and torch applications. the charge pump can be set to regulate two current levels for flash and torch modes. the IS31BL3231 automatically switches between linear and boost modes ensuring that led current does not depend on the led forward voltage. IS31BL3231 provides low cost, space saving solution for driving led. it also integrates thermal and short circuit protection function. IS31BL3231 is available in dfn-10 (3mm 3mm). it operates from 2.7v to 5.5v over the temperature range of -40c to +85c. features ? operates from 2.7v to 5.5v ? up to 90% efficiency in torch mode ? output current up to 750ma ? adjustable output current in flash mode ? minimum external components, no external inductor required ? automatic boost mode ? less than 1a shutdown current ? low ripple and emi ? over voltage protection on output ? short and over temperature protections ? available in dfn-10 (3mm 3mm) package applications ? white led backlighting ? cellular phones ? generic lighting/flash/strobe applications typical application circuit figure 1 typical application circuit copyright ? ? ? 2011 ? integrated ? silicon ? solution, ? inc. ? all ? rights ? reserved. ? issi ? reserves ? the ? right ? to ? make ? changes ? to ? this ? specification ? and ? its ? products ? at ? any ? time ? without ? notice. ? issi ? assumes ? no ? liability ? arising ? out ? of ? the ? application ? or ? use ? of ? any ? information, ? products ? or ? services ? described ? herein. ? customers ? are ? advised ? to ? obtain ? the ? latest ? version ? of ? this ? device ? specification ? before ? relying ? on ? any ? published ? information ? and ? before ? placing ? orders ? for ? products. ? integrated ? silicon ? solution, ? inc. ? does ? not ? recommend ? the ? use ? of ? any ? of ? its ? products ? in ? life ? support ? applications ? where ? the ? failure ? or ? malfunction ? of ? the ? product ? can ? reasonably ? be ? expected ? to ? cause ? failure ? of ? the ? life ? support ? system ? or ? to ? significantly ? affect ? its ? safety ? or ? effectiveness. ? products ? are ? not ? authorized ? for ? use ? in ? such ? applications ? unless ? integrated ? silicon ? solution, ? inc. ? receives ? written ? assurance ? to ? its ? satisfaction, ? that: ? a.) ? the ? risk ? of ? injury ? or ? damage ? has ? been ? minimized; ? b.) ? the ? user ? assume ? all ? such ? risks; ? and ? c.) ? potential ? liability ? of ? integrated ? silicon ? solution, ? inc ? is ? adequately ? protected ? under ? the ? circumstances
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 2 rev. a, 01/03/2011 pin configuration package pin configuration (top view) dfn-10 pin description no. pin description 1 vcc power supply. 2 cp positive input for external flying cap. 3 cn negative input for external flying cap. 4 flash input pin to toggle operation between flash mode and tor c h m od e. 5 en shutdown control input and torch reference select pin. 6 rset set the fb voltage in flash mode. ?? ? ? ? k r v v set fb 2 . 11 / 25 . 1 7 fb feedback input for the current control loop. fb fb led r v i / ? 8 sgnd internal ground pin. 9 pgnd power ground pin. 10 vout charge pump output voltage. thermal pad connect to gnd.
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 3 rev. a, 01/03/2011 ordering information industrial range: -40c to +85c order part no. package qty/reel IS31BL3231-dls2-tr dfn-10, lead-free 2500
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 4 rev. a, 01/03/2011 absolute maximum ratings supply voltage, v dd - 0.3v ~ +6.0v voltage at en pin 0v ~ 7v output current pulse (flash mode) 1a output current pulse (torch mode) 0.4a maximum j unction temperature, t jmax 150c storage temperature range, t stg - 65c ~ +150c operating temperature range, t a ? 40c ~ +85c esd (hbm) 7kv note: stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress rating s only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the sp ecifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. dc characteristics t a = +25c, v cc = 2.7v ~ 5.5v, unless otherwise stated. typical value are t a = +25c, v cc = 4.2v. symbol parameter condition min. typ. max. unit v cc supply voltage 2.7 5.5 v i cc quiescent current v cc = 4.2v v flash = 0v 0.6 ma i sd shutdown current v cc = 5.5v v en = 0v 1 a t on charge pump soft start time 550 s v fb fb reference voltage v flash = v cc r set = 88.7k ? 150 mv v flash = 0v 50 t ovp over temperature protection 160 c v ih input logic high 1.4 v v il input logic low 0.4 v t lo en low time (note 1) 0.3 75 s t hi en high time (note 1) 0.1 75 s t off en shutdown timeout (note 1) 500 s t lat en latch timeout (note 1) 500 s note 1: guaranteed by design.
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 5 rev. a, 01/03/2011 typical performance characteristics output current(ma) supply voltage(v) 0 50 100 150 200 250 3 3. 2 3. 4 3. 6 3. 8 4 4. 2 torch mode i led = 200ma v out = 3.45v figure 2 supply voltage vs. output current (torch mode) en pin 5v/div v out 1v/div i in 500ma/div v cc = 3.6v torch mode i led = 200ma r fb = 0.22 ? figure 4 en on (torch mode) flash pin 5v/div v out 1v/div i out 1a/div v fb 0.2v/div v cc = 3.6v torch mode to flash mode figure 6 torch mode to flash mode output current(ma) supply voltage(v) 0 100 200 300 400 500 600 700 800 3 3.2 3.4 3.6 3.8 4 4.2 flash mode i led = 700ma v out = 3.73v figure 3 supply voltage vs. output current (flash mode) en pin 5v/div v out 1v/div i in 500ma/div v cc = 3.6v flash mode i led = 700ma figure 5 en on (flash mode) flash pin 5v/div v out 1v/div i out 1a/div v fb 0.2v/div v cc = 4.2v torch mode to flash mode figure 7 torch mode to flash mode
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 6 rev. a, 01/03/2011 application information general description the IS31BL3231 is a current-regulated charge pump and ideal for powering high brightness leds for camera flash and torch applications. charge pump the charge pump converter boosts input supply voltage (v cc ) up to a higher output voltage (v out ) to drive led. the charge pump converter only requires three external components: supply decoupling capacitor, output bypass capacitor and flying capacitor. choose low esr capacitors to ensure the best operating performance and place the capacitors as close as possible to the IS31BL3231. the charge pump will start up automatically to offer a higher output voltage when v fb is lower than the setting value. current setting the led current is set by the external resister, r fb , following the equation (1) below. fb fb led r v i / ? (1) v fb is calculated by the equation (2) when IS31BL3231 operates in the flash mode. v fb is set in the table 1 when IS31BL3231 operates in the torch mode. operating mode flash mode by pulling the flash pin to high, IS31BL3231 operates in the flash mode. v fb is set by the r set . ?? ? ? ? k r v v set fb 2 . 11 / 25 . 1 (2) for example, in figure 1, r fb = 0.22 ? , r set = 88.7k ? , so, ?? mv k k v v fb 158 2 . 11 7 . 88 / 25 . 1 ? ? ? ? ? ma mv i led 718 22 . 0 / 158 ? ? ? torch mode by pulling the flash pin to low, IS31BL3231 operates in the torch mode. the v fb is controlled by pulse count control (pcc wire) serial interface. the interface records rising edges of the en pin and decodes them into 8 different states. the 8 voltage level settings available are indicated in table 1. table 1 v fb control (r fb = 0.22 ? ) pulse v fb (typ.) i led (typ.) 1 50mv 227ma 2 60mv 273ma 3 70mv 318ma 4 85mv 386ma 5 100mv 455ma 6 120mv 545ma 7 140mv 636ma 8 170mv 773ma timing control the en pin should be configured as the figure 8. t lat is the latch time. high level should be at last t lat to active the pulse signal. t off is the shutdown time. en pin is pulled low at last t off the ic will be shutdown. figure 8 en pin timing thermal protection the IS31BL3231 has a thermal protection circuit that will shut down the chip if the die temperature rises above the thermal limit until the temperature falls down.
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 7 rev. a, 01/03/2011 classification reflow profiles profile feature pb-free assembly preheat & soak temperature min (tsmin) temperature max (tsmax) time (tsmin to tsmax) (ts) 150c 200c 60-120 seconds average ramp-up rate (tsmax to tp) 3c/second max. liquidous temperature (tl) time at liquidous (tl) 217c 60-150 seconds peak package body temperature (tp)* max 260c time (tp)** within 5c of the specified classification temperature (tc) max 30 seconds average ramp-down rate (tp to tsmax) 6c/second max. time 25c to peak temperature 8 minutes max. figure 9 classification profile
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 8 rev. a, 01/03/2011 tape and reel information
IS31BL3231 integrated silicon solution, inc. ? www.issi.com 9 rev. a, 01/03/2011 package information dfn-10 note: all dimensions in millimeters unless otherwise stated.
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