is31bl3212 integrated silicon solution, inc. ? www.issi.com 1 rev. c, 06/24/2014 four channel constant current led driver june 2014 general description the is31bl3212 provides four regulated current sources, delivers up to 23ma of load current to accommodate four white leds. it requires no charge pump, has no noise and significantly improved the efficiency. the serial digital input is used to enable, disable, and set current for each led with 16 settings down to 0.69ma. a low-current shut down feature disconnects the load from the input and reduces quiescent current typically 1.0ma. the is31bl3212 is available in a pb-free, space-saving 2mm2mm dfn-8 and sot23-6 package. features ? ultra low headroom voltage ? cost effective led driver ? four channel constant current output ideal for driving leds ? best noise and efficiency performance ? ultra low quiescent supply current: 1.0ma (typ.) ? highly integrated design, minimal component ? low shutdown current: 1.0 a (typ.) applications ? white led display backlights ? white led keypad backlights ? cell li-ion battery-operated equipment including pdas, hand-held pcs, cellular phone typical application circuit figure 1 typical application circuit figure 2 application circuit for less than 4 leds note: if less than four leds connected, the left pin can be float ing or connected to gnd. conn ecting to gnd is recommended.
is31bl3212 integrated silicon solution, inc. ? www.issi.com 2 rev. c, 06/24/2014 pin configuration package pin configuration (top view) dfn-8 sot23-6 1 2 34 5 6 vcc d2 d1 d3 gnd en/set pin description no. pin description dfn-8 sot23-6 1 - d4 white led channel. 2~4 6~4 d3~d1 white led channel. 5 3 vcc power supply input. 6 2 gnd ground. 7 1 en/set serial digital input, control the output current. internal 500k ? pull down resistor. 8 - nc no connection. - thermal pad connect to gnd.
is31bl3212 integrated silicon solution, inc. ? www.issi.com 3 rev. c, 06/24/2014 ordering information industrial range: -40c to +85c order part no. package qty/reel is31bl3212-dls2-tr IS31BL3212-STLS2-TR dfn-8, lead-free sot23-6, lead-free 3000 copyright ? ? ? 2014 ? 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
is31bl3212 integrated silicon solution, inc. ? www.issi.com 4 rev. c, 06/24/2014 absolute maximum ratings supply voltage, v cc - 0.3v ~ +6.0v en/set voltage to gnd, v en/set - 0.3v ~ v cc +0.3v maximum junction temperature, t jmax 150c storage temperature range, t stg - 65c ~ +150c operating temperature range, t a ? 40c ~ +85c esd (hbm) esd (cdm) 3kv 1kv note: stresses beyond those listed under ?absolute ma ximum 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 indicat ed in the operational sections of the sp ecifications is not implied. exposure to absolute maximu m rating conditions for extended peri ods may affect device reliability. electrical characteristics t a = 25c, unless otherwise noted. typical values are t a = 25c, v cc = 3.6v. (note 1) symbol parameter condition min. typ. max. unit input power supply v cc operation range 2.7 5.5 v i in operating current 3.0 v cc 5.5, active no load, current data = 1 (note 2) 1.0 ma i shdn shutdown current v en/set = 0v 1.0 2.6 a v hr minimum headroom voltage (dx) i dx = 15ma, v cc = 3.3v 49 mv v hr minimum headroom voltage (dx) i dx = 20ma, v cc = 3.3v 60 mv i dx output current regulation data = 1 (note 2) 23 ma en/set v en/set(l) enable threshold low v cc = 2.7v 0.4 v v en/set(h) enable threshold high v cc = 5.5v 1.4 v t en/set lo en/set low time 0.3 75 s t en/set_hi_min minimum en/set high time (note 3) 1.0 s t en/set_hi_max maximum en/set high time (note 3) 92 s t off en/set off timeout 500 s t lat en/set latch timeout 500 s r en/set down en/set pull down resistor (note 3) 500 k ? note 1: the is31bl3212 is production tested at room temperature but guaran teed to meet performance specifications over other temperatu re range by design, characterization, and correla tion with statistical process controls. note 2: see pcc wire serial interface secti on in application information for more. note 3: guaranteed by design.
is31bl3212 integrated silicon solution, inc. ? www.issi.com 5 rev. c, 06/24/2014 functional block diagram bg output d1~d4 en data vcc gnd ibias en/set
is31bl3212 integrated silicon solution, inc. ? www.issi.com 6 rev. c, 06/24/2014 application information output current capability in order for the output currents to be regulated properly, sufficient headroom voltage (v hr ) is required. the headroom voltage refers to the minimum amount of voltage that must be present across the current source in order to ensure the desir ed current is realizable. to ensure the desired current is obtained, apply the following equations to find the minimum input voltage required: v cc - v ledx v hr notice that if less than four leds connected, the left pin can be floating or connected to gnd. functional description the four constant current source outputs (d1 to d4) can drive four individual leds with a maximum current of 23ma each. the pcc wire serial interface enables the is31bl3212 and sets the current source magnitudes. constant current output level settings the constant current source levels for d1 to d4 are set via the serial interface accord ing to a logarithmic scale. for the whole 16 codes, each code is approximately 1.5db lower than the previous code. in this manner, led brightness appears linear with each increasing code count. because the outputs d1 to d4 are true independent constant current sources, the voltage observed on any single given output will be determined by the actual forward voltage (v f ) for the led being driven. since the output current sources of the is31bl3212 are programmable, no pwm (pulse width modulation) or additional control circuitry is needed to control led brightness. this feature gr eatly reduces the burden on a microcontroller or system ic to manage led or display brightness, allowing the user to "set it and forget it." with its high-speed serial interface (1mhz data rate), the output curr ent of the is31bl3212 can be changed successively to brighten or dim leds, in smooth transitions (e.g., to fade-out) or in abrupt steps, giving the user complete programmability and real-time control of led brightness. pcc wire serial interface the current level magnitude is controlled by pulse count control (pcc wire) serial interface. the interface records rising edges of the en/set pin and decodes them into 16 different states. the 16 current level settings available are indicated in table 1. table 1: current level setting data output(ma/ch) data output(ma/ch) 1 23.0 9 5.8 2 19.6 10 4.8 3 16.1 11 4.1 4 13.8 12 3.5 5 11.8 13 2.8 6 9.9 14 2.1 7 8.1 15 1.4 8 6.9 16 0.7 the pcc wire serial interface has flexible timing. after data is submitted, en/set is held high to latch the data. once en/set has been held in the logic high state for time t lat , the programmed current becomes active and the internal data register is reset to zero. for subsequent current level programming, the number of rising edges corresponding to the desired code must be entered on the en/set pin. pcc wire serial interface timing when en/set is held low for an amount of time greater than t off , the is31bl3212 enters into shutdown mode and draws 1.0a typically from v cc . the internal data register is reset to zero during shutdown.
is31bl3212 integrated silicon solution, inc. ? www.issi.com 7 rev. c, 06/24/2014 led selection the is31bl3212 has low headroom voltage and it is designed to drive white-leds. the drive current will automatically scale down to reduce the led current consumption. input capacitor selection the is31bl3212 is designed to run off of a fixed input voltage. depending on the stability and condition of this voltage rail, it may be necessary to add a small input capacitor to help filter out any noise that may be present on the line. in the ev ent that filtering is needed, ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the is31bl3212. ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. a ceramic capacitor typically has very low esr, is lowest cost, has a smaller pcb footprint, and is non-polarized. low esr ceramic capacitors help to maximi ze charge pump transient response. since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. thermal protection the is31bl3212 has a thermal protection circuit that will shut down the chip if the die temperature rises above the thermal limit. although the is31bl3212 is designed for driving white leds, the device also can be used to drive most types of leds with forward voltage specifications ranging from 2.0v to 4.7v. led applications may include main and sub-lcd display backlighting, camera photo-flash applications, color (rgb) leds, infrared (ir) diodes for remotes, and other loads benefiting from a controlled output current generated from a varying input voltage. since the d1 to d4 output current sources are matched with negligible voltage dependence, the led brightness will be matched regardless of the specific led forward voltage (v f ) levels. in some instances (e.g., in high luminous output applications such as photo flash), it may be necessary to drive high-v f type leds. the low dropout current sources in the is31bl3212 make it capable of driving leds with forward voltages as high as 4.7v at full current from an input supply of 2.7v to 5.0v. outputs can be paralleled to drive high-current leds without complication
is31bl3212 integrated silicon solution, inc. ? www.issi.com 8 rev. c, 06/24/2014 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 3 classification profile
is31bl3212 integrated silicon solution, inc. ? www.issi.com 9 rev. c, 06/24/2014 package information dfn-8
is31bl3212 integrated silicon solution, inc. ? www.issi.com 10 rev. c, 06/24/2014 sot23-6 note: all dimensions in millimet ers unless otherwise stated.
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