MP4600 high-voltage wled driver for large panel tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 1 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. the future of analog ic technology description the MP4600 is an integrated white led driver. it can be applied with mps patent pending technology to drive up to 55 inch lcd tv backlighting, in which the led string voltage can be up to 300v. the novel technology can leverage the led drive power by regulating only a small part of the led drive voltage. as a result, working together with a fixed high voltage source, a low voltage led driver can be used to drive the high voltage led strings with super high power density, high efficiency and low cost due to the low voltage stress, high switching frequency, and smaller size of passive components. MP4600 is a current mode controlled buck- boost regulator. with a 12v input v inl and a high voltage source v inh , it can deliver a regulated voltage (v inh to v inh +43v) to drive a led string with up to 85 leds. it incorporates both dc and pwm dimming onto a single control pin. fault protection includes led open strings protection, output short circuit protection, input over voltage protection, cycle-by-cycle peak current limiting, and thermal shutdown. the MP4600 is available in 10-pin 3x3mm qfn packages. features ? novel power leverage control technology ? unique step-up/down operation ? 0.28 ? internal power mosfet switch ? adjustable switching frequency ? analog and pwm dimming ? 0.198v reference voltage ? 5 a shutdown mode ? stable with low esr output ceramic capacitors ? cycle-by-cycle over current protection ? thermal shutdown protection ? open strings protection ? input over voltage protection ? output short circuit protection ? available in 10-pin 3x3mm qfn packages applications ? tv backlighting ? large lcd panels backlighting ?mps? and ?the future of analog ic technology? are trademarks of monolithic power systems, inc.
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 2 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. ordering information for tape & reel, add suffix ?z (e.g. MP4600dq?z); for rohs compliant packaging, add suffix ?lf (e.g. 4600dq?lf?z) package reference absolute maxi mum ratings (1) supply voltage v dd ? v ss ............................. 60v v sw ? v ss ..............................-0.3v to v in + 0.3v v bst ...................................................... v sw + 6v v ovp ? v ss .......................................-0.3v to +6v v en ? v ingnd .....................................-0.3v to +6v v dim ? v ingnd ....................................-0.3v to +6v v ingnd ? v ss .....................................-0.3v to 60v continuous power dissipation (t a = +25c) (2) ............................................................. 2.5w junction temperature ...............................150 c lead temperature ....................................260 c storage temperature............... -65 c to +150 c recommended operating conditions (3) supply voltage v dd ? v ss .................4.5v to 55v ambient junct. temp (t j ) ........ -40 c to +125 c thermal resistance (4) ja jc 3x3 qfn10 ............................. 50 ...... 12... c/w notes: 1) exceeding these ratings may damage the device. 2) the maximum allowable power dissipation is a function of the maximum junction temperature t j (max), the junction-to- ambient thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous power dissipation at any ambient temperature is calculated by p d (max) = (t j (max)-t a )/ ja . exceeding the maximum allowable powe r dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. internal thermal shutdown circuitry protects the device from permanent damage. 3) the device function is not guaranteed outside of the recommended operating conditions. 4) measured on jesd5 1-7, 4-layer pcb. part number* package top marking free air temperature (t a ) MP4600dq qfn10 (3x 3mm) 9m -40 c to +85 c top view vdd vss ovp fb comp 1 2 3 4 5 sw bst ingnd en/dim rset 10 9 8 7 6 exposed pad on backside (connect to vss)
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 3 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. electrical characteristics v dd = 12v, t a = +25 c, all voltages with respect to v ss , unless otherwise noted. parameters symbol condition min typ max units feedback voltage v fb v dd =4.5v to 55v 0.188 0.198 0.208 v feedback current i fb v fb = 0.22v -50 50 na switch-on resistance r ds(on) 0.28 ? switch leakage i sw-lk v en = 0v, v sw = 0v 1 a current limit i limit 3.0 a oscillator frequency f s v fb = 0.1v, rst=100k 0.5 mhz default oscillator frequency f s-default v fb = 0.1v, rst open 1.35 mhz fold-back frequency f s-fb v fb = 0v, v ovp =0v 250 khz maximum duty cycle d max v fb = 0.1v 90 % minimum on-time t on 100 ns under voltage lockout threshold rising v dd-th 3.0 3.3 3.6 v under voltage lockout threshold hysteresis v dd-hys 100 mv v en = 2v 2.1 en input current i en v en = 0v 0.1 a en off threshold (w/respect to ingnd) v enl v en falling 0.4 v en on threshold (w/respect to ingnd) v enh v en rising 0.6 v minimum en dimming threshold v diml 0.6 0.7 0.8 v maximum en dimming threshold v dimh 1.25 1.4 1.5 v pwm dimming frequency (5) f pwm 100 20k hz supply current (quiescent) i q v en = 2v, v fb = 1v 0.8 1.0 ma supply shut down current i off v en = 0v 3.4 15 a thermal shutdown t th 150 c thermal shutdown hysteresis t hys 20 c open led ov threshold v ovp-th 1.1 1.2 1.3 v open led ov hysteresis v ovp-hys 60 mv note: 5) guaranteed by design.
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 4 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. pin functions pin # name description 1 vdd positive voltage input pin. a decoupling cap is needed to prevent large voltage spikes from appearing at the input. 2 vss negative voltage output pin. this pin is the voltage reference for ovp, fb, comp and rset pins. this node should be placed away fr om switching noise sources. the exposed pad is connected to this pin. 3 ovp over voltage protection pin. use one external resistor voltage divider across ingnd and vss to program ovp threshold. its voltage is referred to vss. when the ovp pin voltage reaches the shutdown th reshold 1.2v, the switch will be tu rned off and will recover when ovp voltage decreases sufficiently. when the ovp pin voltage is lower than 0.4v and fb pin voltage is lower than 0.1v, the chip frequen cy will be folded back. program the ovp pin voltage from 0.4v to 1.2v for normal operation. 4 fb led current feedback input. MP4600 regulates the voltage across the current sensing resistor between fb and vss. connec t the current sensing resist or from the bottom of the led strings to vss. the fb pin is connected to the bottom of the led strings. the regulation voltage is 0.198v. 5 comp output of error amplifier. connect a 1nf or la rger capacitor on comp to improve the stability and to provide a soft on at start up or pwm dimming. 6 rset connect to a resistor to vss to set the switching frequency. 7 en/dim on/off control input and dimming command in put. its voltage is referred to ingnd. a voltage greater than 0.7v will turn on the chip. when the en/dim pin voltage rises from 0.7v to 1.4v, the led current will change from 0% to 100% of the maximum led current. to use pwm dimming, apply a 100hz to 20khz square wave signal with amplitude greater than 1.5v to this pin. 8 ingnd input ground reference. this pin is the reference for the en/dim signal. 9 bst bootstrap. a capacitor is connected between sw and bst pins to form a floating supply across the power switch driver. 10 sw switch output. sw is the source of the in ternal mosfet switch. connect to the power inductor and cathode of the schottky rectifier. exposed pad should be connected to vss.
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 5 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. operation the MP4600 is a current mode controlled buck- boost regulator. the sensing resistor senses the led current and feeds it back to an error amplifier, which regulates it to 198mv with an inside compensation network. the comp pin is the output of the error amplifier. the inductor peak current is proportional to the comp pin voltage. an increase of the comp voltage increases the current delivered to the output. open led protection if the led is open, there is no voltage on the fb pin. the duty cycle will increase until v dd - v ss reaches to 55v or v ovp -v ss reaches the shutdown threshold set by the external resistor. the top switch will turn off until the voltage v dd - v ss and v ovp -v ss decreases sufficiently. dimming control the MP4600 allows both dc and pwm dimming. when the voltage on en is <0.6v, the chip is turned off. for analog dimming, when the voltage on en is from 0.7v to 1.4v, the led current will change from 0% to 100% of the maximum led current. if the voltage on en pin is higher than 1.4, maximum led current will be generated. for pwm dimming, its amplitude (v dim ? v ingnd ) must exceed 1.5v. the pwm waveform is internally clamped to 0.198v. comp figure 1?functional block diagram
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 6 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. application information setting the led current an external resistor r sense is used to set the maximum led current through the use of the equation: led sense i 0.198v r = setting the switching frequency an external resistor r set is used to set the switching frequency f s according to the following curve: frequency vs. rset 0 200 400 600 800 1000 1200 1400 0 50 100 150 200 250 frequency (khz) series1 if rset pin is floating, the setting frequency is the default value 1.35mhz. selecting the inductor inductor selection is related to the input voltage, output voltage, and led current. select the inductor to make the circuit always operate in continuous current mode (ccm). the inductance is designed as: i n o u t s i n o u t l v v l f ( v v ) i ? = ?+ ? , where i l is the inductor peak-to-peak current ripple. design i l as about 40% to 60% of the inductor average current, which is: o u t l _ a v g l e d i n v i i ( 1 ) v =?+ . make sure the inductor is not saturated at the maximum peak current, which is: l _ p k l _ a v g l i i 0 . 5 i =+? . selecting the input capacitor the input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. ceramic capacitors with x5r or x7r dielectrics are highly recommended because of their low esr and small temperature coefficients. enough capacitance is required for limited input voltage ripple v in , which should be normally less than 5~10% of the dc value. l _ a v g o u t i n s i n i n o u t i v c f v ( v v ) ? > ? ? + selecting the output capacitor the output capacitor keeps the output voltage ripple v out small (normally less than 1~5% of the dc value) and ensures feedback loop stable. the output capacitor impedance should be low at the switching frequency. ceramic capacitors with x5r or x7r dielectrics are recommended for their low esr characteristics. l e d o u t o u t s o u t i n o u t i v c f v ( v v ) ? > ? ? + pc board layout the high current paths (vss, vdd and sw) should be aced very close to the device with short, direct and wide traces. the input capacitor needs to be as close as possible to the vdd and vss pins. the external feedback resistors should be placed next to the fb pin. keep the switch node traces short and away from the feedback network.
MP4600 ? white led driver for up to 55 inch tv backlighting MP4600 rev. 0.91 www.monolithicpower.com 7 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical application circuits 1 1 1 2 2 2 3 3 3 figure 2?white led driver application for tv applications
MP4600 ? white led driver for up to 55 inch tv backlighting notice: the information in this document is subject to change wi thout notice. please contact m ps for current specifications. users should warrant and guarantee that third party intellectual property rights ar e not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. MP4600 rev. 0.91 www.monolithicpower.com 8 1/6/2012 mps proprietary information. unaut horized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. package information 3mm x 3mm qfn10 side view top view 1 10 6 5 bottom view 2.90 3.10 1.45 1.75 2.90 3.10 2.25 2.55 0.50 bsc 0.18 0.30 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.70 0.50 0.25 recommended land pattern 2.90 note: 1) all dimensions are in millimeters. 2) exposed paddle size does not include mold flash. 3) lead coplanarity shall be 0.10 millimeter max. 4) drawing conforms to jedec mo-229, variation veed-5. 5) drawing is not to scale. pin 1 id see detail a 2.50 0.70 pin 1 id option b r0.20 typ. pin 1 id option a r0.20 typ. detail a 0.30 0.50 pin 1 id index area
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