RT9368 1 ds9368-07 april 2011 www.richtek.com ordering information general description the RT9368 is a high efficiency and cost effective charge pump white led driver. it supports up to 4 white leds with regulated constant current for uniform intensity. the RT9368 maintains the highest efficiency by utilizing a x1/ x1.5/x2 charge pump and low dropout current regulators. user can easily configure each led current from 1.25ma to 20ma by a pwm dimming control. the dimming of white leds current can be achieved by applying a pwm signal to the en pin. RT9368 is available i n a wqfn 3x3-16l pa ckage. features z z z z z very high efficiency over 80% of battery life z z z z z support up to 4 white leds z z z z z support up to 80ma output current z z z z z 1% typical led current matching z z z z z soft start function z z z z z auto charge pump mode selection z z z z z 250khz fixed frequency oscillator z z z z z output over voltage protection z z z z z pwm dimming control z z z z z low input noise and emi z z z z z rohs compliant and 100% lead (pb)-free 4-channel charge pump white led driver with low dropout current source applications z mobile phone, dsc, mp3 z white led backlighting z lcd display supply pin configurations (top view) wqfn-16l 3x3 marking information for marking information, contact our sales representative directly or through a richtek distributor located in your area. note : richtek products are : ` rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ` suitable for use in snpb or pb-free soldering processes. led4 en 12 11 10 9 13 14 15 16 1 2 3 4 8 7 6 5 c1p gnd nc c2p gnd iset vout vin c2n c1n vin led3 led2 led1 17 RT9368 package type qw : wqfn-16l 3x3 (w-type) lead plating system p : pb free g : green (halogen free and pb free)
RT9368 2 ds9368-07 april 2011 www.richtek.com typical application circuit vout led4 led2 led1 led3 iset en vin c1n c2p c2n c out c in r set RT9368 gnd 2.2uf c1p c pump2 c pump1 2.2uf gpio + vout led4 led2 led1 led3 iset en vin c1n c2p c2n c out c in r set RT9368 gnd 2.2uf c1p c pump2 c pump1 2.2uf gpio + vout led4 led2 led1 led3 iset en vin c1n c2p c2n c out c in r set RT9368 gnd 2.2uf c1p c pump2 c pump1 2.2uf gpio + figure 1. 4-wleds application circuit with pwm dimming function figure 2. 3-wleds application circuit with pwm dimming function figure 3. 2-wleds application circuit with pwm dimming function c pump1 c pump2 maximum output current (total) 0.22uf 0.22uf 60ma 0.47uf 0.47uf 100ma 1uf 1uf 160ma
RT9368 3 ds9368-07 april 2011 www.richtek.com functional pin description pin no. pin name pin function 1 led 4 output current for led4. (if not in use, this pin must be connected to gnd). 2, 17 (exposed pad) nc no internal connection. 3, 10 gnd ground. 4 c1p positive terminal of bucket capacitor 1. 5 vin power input voltage. 6 c2n negative terminal of bucket capacitor 2. 7 c1n negative terminal of bucket capacitor 1. 8 vout output voltage source. 9 c2p positive terminal of bucket capacitor 2. 11 iset led current is set by the value of the resistor r set connected from the iset pin to ground. do not short the iset pin to gnd directly. 12 en chip enable (active high). note that this pin is high impedance. 13 vin power input voltage. 14 led 1 output current for led1. (if not in use, this pin must be connected to gnd). 15 led 2 output current for led2. (if not in use, this pin must be connected to gnd). 16 led 3 output current for led3. (if not in use, this pin must be connected to gnd). function block diagram en led1 led4 led2 led3 250khz osc 16 steps pulse dimming controller soft start circuit current source shutdown delay vin vout gate driver uvlo ovp min vds + - c1p c2p c2n c1n mode decision current bias vr2 gnd iset
RT9368 4 ds9368-07 april 2011 www.richtek.com electrical characteristics (v in = 3.6v, c in = c out = c fly = 1uf (esr = 30m ), t a = 25 c, unless otherwise specification) to be continued absolute maximum ratings (note 1) z supply input voltage ------------------------------------------------------------------------------------------------------ ? 0.3v to 6v z other i/o pin voltage ----------------------------------------------------------------------------------------------------- ? 0.3v to 6v z power dissipation, pd @ t a = 25 c wqfn-16l 3x3 ------------------------------------------------------------------------------------------------------------ 1.47w z package thermal resistance (note 2) wqfn-16l 3x3, ja ------------------------------------------------------------------------------------------------------- 68 c/w z junction temperature ----------------------------------------------------------------------------------------------------- 150 c z lead temperature (soldering, 10 se c.) ------------------------------------------------------------------------------- 260 c z storage temperature range -------------------------------------------------------------------------------------------- ? 40 c to 150 c z esd susceptibility (note 3) hbm (human body mode) ---------------------------------------------------------------------------------------------- 2kv mm (ma chine mode) ------------------------------------------------------------------------------------------------------ 200v recommended operating conditions (note 4) z junction temperature range -------------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range -------------------------------------------------------------------------------------------- ? 40 c to 85 c parameter symbol test condition min typ max units input input supply voltage v in 2.8 -- 5.0 v under-voltage lockout threshold v in rising 1.6 2.1 2.5 v under-voltage lockout hysteresis -- 100 -- mv quiescent of x1 mode i q_x1 x1 mode, no load, all led pins connected to gnd, v in = 4v 0.5 1 2 ma quiescent of x2 mode i q_x2 x2 mode, no load, all led pins floating, v in = 3.5v 1.5 2.5 5 ma shutdown current i shdn v en = 0.4v, v in = 2.8v to 5.5v 0 0.1 10 a x1 mode to x1.5 mode transition voltage (v in falling) v ts_x1.5 v f = 3.5v, i out = 80ma, i ledx = 20ma -- 3.7 -- v x1.5 mode to x2 mode transition voltage (v in falling) v ts_x2 v f = 3.5v, i out = 80ma, i ledx = 20ma -- 3.0 -- v hysteresis of mode transition -- 100 -- mv output current range of i ledx 2.8 < v in < 5.5@v f = 3.2, i out = 60ma 3.0 < v in < 5.5@v f = 3.4, i out = 80ma 3.3 < v in < 5.5@v f = 3.8, i out = 80ma 1.25 -- 20 ma i ledx accuracy i led-err 100% setting ? 8 -- +8 % current matching ? 5 -- +5 %
RT9368 5 ds9368-07 april 2011 www.richtek.com note 1. stresses listed as the above "absolute maximum ratings" may cause permanent damage to the device. these are for stress ratings. functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. note 2. ja is measured in the natural convection at t a = 25 c on a low effective thermal conductivity test board of jedec 51-3 thermal measurement standard. note 3. devices are esd sensitive. handling precaution is highly recommended. note 4. the device is not guaranteed to function outside its operating conditions. parameter symbol test condition min typ max units enable logic-high v ih 1.5 -- -- v e n threshol d voltage logic-low v il -- -- 0.4 v logic-high i ih v ih = v in -- 1 10 a en current logic-low i il v il = gnd -- 1 10 a en low time for shut down t shdn pwm dimming -- 8 -- ms frequency pwm dimming frequency f pwm minimum turn on > 30 s 250 -- 32k hz oscillator fr equency f osc -- 250 -- khz
RT9368 6 ds9368-07 april 2011 www.richtek.com typical operating characteristics v in = 3.6v en pin shutdown response v in ac (100mv/div) time (5ms/div) v out (2v/div) en (1v/div) i led (10ma/div) v in = 3.3v x1.5 mode inrush current response v in ac (200mv/div) time (50us/div) v out (2v/div) en (1v/div) i in (200ma/div) output voltage v s. input voltage 3 3.5 4 4.5 5 5.5 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 input voltage (v) output voltage (v) led current vs. input voltage 15 16 17 18 19 20 21 22 2.6 3 3.4 3.8 4.2 4.6 5 5.4 input voltage (v) led current (ma) led1 led2 led3 led4 efficiency vs. input voltage 50 55 60 65 70 75 80 85 90 95 2.6 3 3.4 3.8 4.2 4.6 5 5.4 5.8 input voltage (v) efficiency (%) x1 x2 x1.5 input current vs. input voltage 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 2.6 3.1 3.6 4.1 4.6 5.1 5.6 input voltage (v) input current (ma) x2 mode x1 mode
RT9368 7 ds9368-07 april 2011 www.richtek.com v in = 3.0v, c in = c out = 2.2 f x2 mode ripple & spike v in (200mv/div) time (1us/div) v out (200mv/div) c2n (2v/div) v in = 3.1v, c in = c out = 2.2 f x1.5 mode ripple & spike v in (200mv/div) time (1us/div) v out (200mv/div) c2n (2v/div)
RT9368 8 ds9368-07 april 2011 www.richtek.com applications information the RT9368 is a high efficiency charge pump white led driver. it provides 4 channels low dropout voltage current source to regulated 4 white leds current. for high efficiency, the RT9368 implements x1/x1.5/x2 mode charge pump. an external r set is used to set the current of white led. RT9368 has input current regulation to reduce the input ripple. soft start the RT9368 includes a soft start circuit to limit the inrush current at power on and mode switching. soft start circuit holds the input current level long enough for output capacitor c out reaching a desired voltage level. when the soft start off, the RT9368 won ? t sink spike current from v in . mode decision the RT9368 uses a smart mode decision method to select the working mode for maximum efficiency. mode decision circuit senses the output and led voltage for up/down selection. dimming control when an external pwm signal is connected to the en pin, brightness of white led is adjusted by the duty cycle. led current setting the current of white led connected to RT9368 can be set by r set . every current flows through the white led is 250 times greater than the current of r set . the white led can be estimated by following equation : where v set = 1.2v, and r set is the resistor connected from iset to gnd. if the led is not used, the leds pin should be connected to gnd. figure 4 shows the connection for 3leds application, led4 pin is connection to gnd directly. led4 led2 led1 led3 figure 4. application for 3 leds layout consideration the RT9368 is a low dropout current source for white led driver. careful pcb layout is necessary. for best performance, place all peripheral components as close to the ic as possible. a short connection is highly recommended. the following guidelines should be strictly followed when designing a pcb layout for the RT9368. ` all the traces of led pins running from chip to leds should be wide and short to reduce the parasitic connection resistance. ` input capacitor (c in ) should be placed close to vin (pin 5) and connected to ground plane. the trace of vin in the pcb should be placed far away the sensitive devices or shielded by the ground. ` the gnd should be connected to a strong ground plane for heat sinking and noise protection. ` the connection of r set should be isolated from other noisy traces. the short wire is recommended to prevent emi and noise coupling. ` output capacitor (c out ) should be placed close to v out and connected to ground plane to reduce noise coupling from charge pump to leds. ` 6. the traces running from pins to flying capacitor should be short and wide to reduce parasitic resistance and prevent noise radiation. 250 ) r v ( i set set led =
RT9368 9 ds9368-07 april 2011 www.richtek.com figure 5 c in c2 battery ground plane r set 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 c out nc gnd c1p led4 c2p gnd iset en c2n c1n vout vin led3 led2 led1 vin c1 all the traces of led pins running from chip to leds should be wide and short to reduce the parasitic connection resistance. input capacitor (c in ) should be placed close to v in (pin 5) and connected to ground plane. the trace of v in in the pcb should be placed far away the sensitive devices or shielded by the ground. the gnd should be connected to a strong ground plane for heat sinking and noise protection. the connection of r set should be isolated from other noisy traces. the short wire is recommended to prevent emi and noise coupling. output capacitor (c out ) should be pla ced close to v out and connected to ground plane to reduce noise coupling from charge pump to leds. the traces running from pins to flying capacitor should be short and wide to re duce parasitic resistance and prevent noise radiation.
RT9368 10 ds9368-07 april 2011 www.richtek.com richtek technology corporation headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 richtek technology corporation taipei office (marketing) 5f, no. 95, minchiuan road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)86672399 fax: (8862)86672377 email: marketing@richtek.com information that is provided by richtek technology corporation is believed to be accurate and reliable. richtek reserves the ri ght to make any change in circuit design, specification or other related things if necessary without notice at any time. no third party intellectual property inf ringement of the applications should be guaranteed by users when integrating richtek products into any application. no legal responsibility for any said applications i s assumed by richtek. outline dimension a a1 a3 d e 1 d2 e2 l b e see detail a w-type 16l qfn 3x3 package note : the configuration of the pin #1 identifier is optional, but must be located within the zone indicated. det ail a pin #1 id and tie bar mark options 1 1 2 2 dimensions in millimeters dimensions in inches symbol min max min max a 0.700 0.800 0.028 0.031 a1 0.000 0.050 0.000 0.002 a3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 d 2.950 3.050 0.116 0.120 d2 1.300 1.750 0.051 0.069 e 2.950 3.050 0.116 0.120 e2 1.300 1.750 0.051 0.069 e 0.500 0.020 l 0.350 0.450 0.014 0.018
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