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MP3306 30v, 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 1 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. the future of analog ic technology description the MP3306 is a stepup converter designed for driving white leds from 3v to 12v power supply. the MP3306 uses current mode, fixed frequency architecture to regulate the led current, which is measured through an external highside current sense resistor. the low 202mv feedback voltage and synchronous rectification reduces power loss and improves efficiency. the MP3306 is turned off if an overvoltage condition is present due to an open circuit condition. the output disconnect feature allows the output to be completely discharged. the MP3306 includes undervoltage lockout, current limiting, output short protection and thermal overload protection. the MP3306 is available in small 12pin qfn (2mm x 2mm) package. features ? 3v~12v input voltage ? analog dimming and pwm dimming ? outputtoinput disconnect in shutdown mode ? programmable open load shutdown ? output short protection ? low 202mv feedback voltage with +/3% accuracy ? uvlo, thermal shutdown ? available in 2mm x 2mm qfn12 package applications ? smart phone, mid, pda ? digital still cameras ? small lcd displays all mps parts are lead free and adhere to the rohs directive. for mps green status, please visit mps website under quality assu rance. mps and the future of analog ic technology are registered trad emarks of monolithic power systems, inc. typical application led 1 led 6 sw en g n d m p3306 l1 c 1 c 2 vin en g n d r 1 vc c in pw mo c 5 o vp r 2 r 3 l c 3 pm wi pw mi b st o u t c 4 fb
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 2 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. ordering information part number* package top marking MP3306eg qfn12 (2x2mm) 3y * for tape & reel, add suffix Cz (e.g. MP3306egCz). for rohs compliant packaging, add suffix Clf (e.g. MP3306egClfCz) package reference pw m o en fb o vp 1 2 3 4 7 8 9 10 bs t g n d sw in 5 12 l pw m i 11 o u t vc c 6 absolute maximum ratings (1) v sw, v out, v fb ....................................0.5v to 35v v bst ................................. ................. .... v sw +6v v in, v l, ............................................ 0.5v to 14v v en, v ovp, v pwmi, v pwmo, v cc ........... 0.3v to 6.5v continuous power dissipation (t a = +25c) (2) ....1.6w storage temperature ............... 55 c to +150 c recommended operating conditions (3) in supply voltage v in ........................ 3v to 12v v sw ................................................ 0.5v to 30v operating junct. temp (t j ) ...... 40 c to +125 c thermal resistance (4) ja jc qfn12 (2 x 2mm) ................... 80 ...... 16 .. . c/w notes: 1) exceeding these ratings may damage the device. 2) the maximum allowable power dissipation is a functi on of the maximum junction temperature t j (max), the junctionto ambient thermal resistance ja , and the amb ient temperature t a . the maximum allowable continuous power dissipatio n at any ambient temperature is calculated by p d (max) = (t j (max)t a )/ ja . exceeding the maximum allowable power dissipation will cause excessive die temperature, a nd the regulator will go into thermal shutdown. internal thermal shutdown circuitry protects the device from permane nt damage. 3) the device is not guaranteed to function outside of its operating conditions. 4) measured on jesd517, 4layer pcb.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 3 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. electrical characteristics v in = v en = 5v, t a = +25 c, all voltages with respect to gnd, unless otherwi se noted. parameters symbol condition min typ max units operating input voltage v in 3 12 v vcc voltage v vcc v in > 5.5v, v en = 3v 3.7 3.9 4.1 v supply current (shutdown) i sd v en = 0v 0.1 1 a supply current (quiescent) i qs v en = 5v, v out v fb = 0.5v 300 380 460 a switching frequency f sw 550 690 830 khz maximum duty cycle d max v fb = v out 93 % under voltage lockout in under voltage lockout uvlo v in rising 2.5 2.7 2.9 v under voltage lockout hysteresis 130 mv protection ovp threshold v ov p th 1.18 1.22 1.26 v sw current limit ( 5 ) duty cycle = 60% 1.8 a thermal shutdown ( 5 ) 150 c enable en off threshold v enlo v en falling 0.6 v en on threshold v enhi v en rising 1.1 v dimming pwmi low threshold v pwmi lo v pmwi falling 0.8 v pwmi high threshold v pwmi hi v pmwi rising 1.2 v pwmi input frequency f pwmi 0.1 50 khz minimum pwmo dimming threshold v pwmomin v fb = v out 25 mv maximum pwmo dimming threshold v pwmomax v out v fb = 0.2v 850 mv feedback fb voltage v fb v en = 3v 196 202 208 mv fb input bias current i fb v en = 3v 3 7 11 a disconnect switch onresistance ( 5 ) r nd on 0.5 output switch highside nmos onresistance ( 5 ) r n h on 0.6 lowside nmos onresistance ( 5 ) r nl on 0.6 notes: 5) guaranteed by design
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 4 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. pin functions pin # name pin function 1 in input supply pin. it provides the power for interna l driver an d logic circuit. must be locally bypassed. 2 vcc the internal linear regulator output. vcc provides power supply for the internal mosfet switch gate driver and the internal control circuit ry .bypass vcc to gnd with a ceramic capacitor. 3 en en control input. a voltage greater than 1.1v turns the part on and less than 0.6 v turns the part off. 4 pwmi apply a pwm signal on this pin for brightness contr ol. this signal is uniformed and filtered at pwmo pin with an internal 100k resistance. with a capacitor at pwmo pin, the dut y cycle from 0% to 100% at pwmi pin is converted to 0v to 1 .2v dc voltage at pwmo pin. 5 pwmo pwm filter output. connect a capacitor from pwmo t o gnd. the voltage on this pin range 0v to 1.2v linearly controls the feedback voltage f rom 0v to 0.2v. to use pwm dimming, connect the pwm input signal to pwmi pin. to use analog dimming, connect the analog input vol tage to pwmo pin. 6 ovp over voltage protection pin. use one external resistor voltage d ivider to program ovp threshold. when the ovp pin voltage reaches the shu tdown threshold 1.22 v, the ic will be turned off and latch up until en is toggled again. 7 fb feedback input. the MP3306 regulate s the voltage across the current sense resistor between fb and vout. connect a current sense resist or from vout to the led string. connect the anode of the led string to fb. the regu lation voltage is 202mv. 8 gnd ground. 9 out the output terminal. connec t the output cap on this pin, the output capacitor must be ceramic type and be placed as short as possible bet ween out pin and gnd pin. 10 sw power switch node. sw is the drain of the internal low side mosfet switch. connect the power inductor to sw. 11 bst bootstrap. a capacitor is connected between sw and bst pins to form a floating supply to drive the high side mosfet. 12 l power input pin. l is the source of internal disconnection mosfet. connect the induc tor to this pin.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 5 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical performance characteristics v in =5v, v en =5v, 8 leds in series, 20ma, unless otherwise noted . v sw 10v/div. i induc tor 200ma/div. v ou t 10v/div. steady statev in = 3v v sw 10v/div. v en 5v/div. i l 100ma/div. i led 20ma/div. en startup en shutdown v sw 10v/div. v out 10v/div. i led 20ma/div. v pwm 5v/div. v sw 10v/div. v out 5v/div. i led 10ma/div. v pwm 5v/div. v sw 10v/div. v ou t 10v/div. i led 20ma/div. v ov p 500mv/div. v sw 10v/div. v ou t 10v/div. i l 500ma/div. i ou t 200ma/div. v sw 10v/div. v ou t 10v/div. i l 100ma/div. i led 20ma/div. efficiency v in (v) 78 80 82 84 86 88 90 92 94 2 4 6 8 10 12 14 v sw 10v/div. v en 5v/div. i l 100ma/div. i led 20ma/div.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 6 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. function diagram figure 1functional block diagram
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 7 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. operation the MP3306 uses a constant frequency, peak current mode step up regulator architecture to regulate the current flowing through series string of white leds. the operation of the MP3306 can be understood by referring to the block diagram of figure 1. at the start of each oscillator cycle the low side fet (m2) is turned on through the control circuitry. to prevent subharmonic oscillations at duty cycles greater than 50 percent, a stabilizing ramp is adde d to the output of the current sense amplifier and th e result is fed into the positive input of the pwm comparator. when this voltage equals the output voltage of the error amplifier the power fet is turned off. then the inductor current flows into th e output capacitor and led load through internal high side nchannel mosfet (m3), which forces the inductor current to decrease. the voltage at the output of the error amplifier is an amplified version of the difference between the 200mv reference voltage and the feedback voltage. in this way the led current is regulated accurately . if the feedback voltage starts to drop, the output of the error amplifier increases. this result in more current flowing through the high side power fet, thus increasing the power charged in inductor and delivered to the output. MP3306 provides the analog and pwm dimming solution, the internal resistor and external capaci tor one pwmo pin filters the pwm dimming signal on pwmi pin to dc level that program the internal reference to accomplish the analog dimming function. when floating the pwmo pin, pwm dimming function works. open load protection shuts off the MP3306 if the output voltage goes too high. in some cases an led may fail, this results in the feedback voltage always being zero. the part then runs at maximum duty cycle boosting the output voltage up. if the output ever exceeds the programmable ovp threshold, the MP3306 will shut down. the part does not switch again until the en pin or v in is toggled. during shutdown mode when en is low, the ic keeps the internal highside nchannel mosfet (m1) off to disconnect the output from input. MP3306 has cycle by cycle current limit to protect the load and ic from over current. and the internal mosfet (m1) limits the input current to prevent system damage when short v out condition occurs.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 8 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. application information vin en dim gnd led+ led- tp6 tp5 tp4 tp3 tp2 tp1 u1 MP3306 l 12 3 4 5 6 8 7 10 11 9 12 sw bs t ou t invcc en pwmi pwmo ov p gnd fb jp1 c6 10nf r1 51k r50 r3 51k r8 205k r9 10k c5 ns r7 ns r2 0 r4 ns figure 23v~12v input, typical application driving 8 wleds in series figure 2 shows a typical application circuit that can drive up to 8 white leds with 20ma. a 0.22~2.2f output capacitor is sufficient for most applications. the inductor with low dc inductor resistance (dcr) will improve efficiency. two 4.7f ceramic capacitors provide sufficient input decoupling. selecting the inductor the inductor forces a higher output voltage driven from a lower input voltage. a larger inductor value results in less ripple current, a lower peak inductor current, and reduces stress on the internal nchannel mosfet. however, largervalue inductor has a larger physical footprint, higher series resistance, and lower saturation current. choose an inductor that does not saturate under the worstcase load conditions. calculate the required inductance value using the following equations: 2 out sw load v d (1 d) l 2 f i ? in out v d 1 v = ? where v in and v out are the input and output voltages, f sw is the switching frequency, i load is the led load current, and is the efficiency. setting the led current the led current is controlled by the current setting resistor, r1. the current through the leds is given by: i led = 202mv/r1. table 1 shows the selection of resistors for a given led current. table 1i led vs. r1 r set i led (ma) r1 ( ) 1 200 5 40 10 20 20 10 60 3.33 180 1.11 200 1 the internal ramped compensation voltage added to the current sense amplifier reduces the maximum output current as the duty cycle increases. as more leds are added, the output voltage rises but the maximum current delivered to the load falls as well. figure 3 shows the current limit curve, and the max led current is gotten as the formula. in load(max) pk sw v d i (i ) (1 d) 0.8 2 l f = ? ? where, i pk is the peak current corresponding duty cycle from current limit curve, the l is inductor, the 0.8 means the margin coefficient.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 9 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. current limit vs. duty 0 10 20 30 40 50 60 70 80 90100 0 0.5 1 1.5 2 figure 3current limit curve analog and pwm dimming MP3306 provides 2 types of dimming solutions, analog dimming and pwm dimming. for analog, connect an external capacitor on pwmo pin to form the low pass filter with internal resistor r, the pwm dimming signal on pwmi pin is filtered to dc signal to set the internal reference to accomplish the analog dimming. the time constant should be ten times greater than a pwm waveform cycle: pwm rc 10 t > ? for pwm dimming, floating pwmo pin and apply the pwm dimming signal on pwmi pin. setting over voltage protection threshold open load protection will shut off the MP3306 if the output voltage goes too high. in some cases an led may fail, this will result in the feedback voltage always being zero. the part boots the output voltage higher and higher. if the output voltage ever exceeds the programmed ovp threshold as the formula, ovp v =1.22 (1 r2 / r3) + the MP3306 will shut down. the part will not switch again until the power is recycled. layout considerations careful attention must be paid to the pcb board layout and components placement. proper layout of the high frequency switching path is critical to prevent noise and electromagnetic interference problems. the loop of MP3306s internal low side mosfet, synchronous mosfet, and output capacitor is flowing with high frequency ripple current, it must be minimized. so the output capacitor should be placed to ic as close as possible.
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 10 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. typical application circuit figure 4 4 leds in series 20ma figure 5 4 leds in series 20ma
MP3306 - -- - 30v 700khz synchronous stepup white led driver MP3306 rev.1.0 www.monolithicpower.com 11 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. figure 6 6 leds in series with pwm dimming figure 7 3 leds in series 20ma with 5~10v input vo ltage
MP3306 - -- - 30v 700khz synchronous stepup white led driver notice: the information in this document is subject to cha nge without notice. users should warrant and guaran tee that third party intellectual property rights are not infringe d upon when integrating mps products into any appli cation. mps will not assume any legal responsibility for any said applic ations. MP3306 rev.1.0 www.monolithicpower.com 12 3/6/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibi ted. ? 2013 mps. all rights reserved. package information qfn12 (2x2mm)

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