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MP4601 white led driver for large size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 1 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology description the MP4601 is an integrated white led driver. it can be applied with mps patent pending technology to drive up to 60 inch or larger size lcd tv backlighting, in which the led string voltage can be up to 350v. the novel technology can leverage the led drive power by regulating only small portion 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. MP4601 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 +63v) to drive a led string with up to 100 leds. it can drive an external switch, which is in series with the led string, to achieve over 1:1000 dimming ratio. analog dimming can be applied in the same time to further improve the dimming ratio. fault protection includes led open strings protection, output short circuit protection, cycle-by-cycle peak current limiting, and thermal shutdown. MP4601 is available in tssop16-ep and soic16 packages. features ? novel power leverage control technology ? unique step-up/down operation ? up to 99.5% efficiency ? 0.5 ? internal power mosfet switch ? switching frequency synchronization ? over 1:1000 dimming ratio ? analog and pwm dimming ? 5% 200mv reference voltage ? 850a quiescent current ? 10a shutdown mode ? programmable cycle-by-cycle over current protection ? thermal shutdown protection ? led string open and short protection ? fault output for short led protection ? output short circuit protection ? available in tssop16-ep and soic16 packages applications ? tv backlighting ? large lcd panels backlighting for mps green status, please visit mps website under quality assurance. ?mps? and ?the future of analog ic technology? are trademarks of monolithi c power systems, inc.
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 2 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical application 120v clk/syn dim en vout vin 12v c1 10 rfst 60k rsc 60k rocp 100k ccomp 100pf rfb 2 r1 800k r2 12k cbst 100nf l1 22 vin ocp ingnd en slope dim syn fst comp vss fb dgd ovp fault bst sw MP4601 c out 2.2 r3 100k efficiency (%) external voltage (v) efficiency vs. external bus voltage v inl =12v, v led =240v, i led =100ma, external bus voltage, v inh =180~236v 90 91 92 93 94 95 96 97 98 99 100 180 190 200 210 220 230 240
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 3 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. ordering information part number package top marking free air temperature (t a ) MP4601ef* tssop16-ep MP4601ef -20 c to +85 c MP4601es soic16 MP4601es * for tape & reel, add suffix ?z (e.g. MP4601ef?z); for rohs compliant packaging, add suffix ?lf (e.g. MP4601ef?lf?z) package reference absolute maxi mum ratings (1) v vin ? v ss ........................................ -0.3v to 85v v ingnd ? v ss ..................................... -0.3v to 85v v sw ? v ss ............................ -0.3v to v vin + 0.3v v bst ...................................................... v sw + 6v v dgd ? v ss ..................................... -0.3v to +12v v slope, v ocp ? v ss ........................... -0.3v to +6v v ovp , v fb , v com , v fst ? v ss ............. -0.3v to +6v v fault , v dim , v syn , v en ? v ingnd ....... -0.3v to +6v continuous power dissipation (t a = +25c) (2) tssop16-ep ............................................. 2.7w soic16 ...................................................... 1.6w junction temperature ............................... 150 c lead temperature .................................... 260 c storage temperature ............... -65 c to +150 c recommended operating conditions (3) supply voltage v vin ? v ss ................ 4.5v to 75v v dim , v en , v syn ? v ingnd ......................... 0v to 5v operating junct. temp (t j ). ..... -40 c to +125 c thermal resistance (4) ja jc tssop16-ep ......................... 45 ...... 10 ... c/w soic16 .................................. 80 ...... 30 ... 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. 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 top view exposed pad for tssop20f only vin ocp ingnd en slope dim syn fst comp vss fb dgd ovp fault bst sw 1 2 3 4 16 15 14 13 12 11 10 9 5 6 7 8 top view pin 1 id vin ingnd en slope dim syn fst fault ocp comp vss fb dgd ovp bst sw tssop16-ep soic16
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 4 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. electrical characteristics v vin = 12v, pwm and ad pins floating, r fst =51k ? , t a = +25 c, v vss =v ingnd =0v, unless otherwise noted. parameters symbol condition min typ max units fb feedback voltage v fb 190 200 210 mv fb input current i fb v fb = 0.2v -0.1 0.1 a vin uvlo rising v vinth 2.7 3.5 4.1 v vin uvlo hysteresis v vinhys 70 mv shut down current i off v en =0v 10 a supply current (quiescent) i q v pwm = 0v, v fb = 250mv 850 1000 a switch-on resistance r ds ( on ) 0.5 ? switch leakage i swlk v vin =80v, v en =0v, v pwm =0v, v sw =0v 10 a switch current limit i s_max ocp pin open 2.5 a ocp output voltage v ocp 1.1 1.2 1.3 v oscillator frequency f sw fst pin open 0.8 0.95 1.2 mhz rfst = 200k ? 200 280 390 khz fst output voltage v fst 1 1.1 1.2 v fold-back frequency f swfb v fb = v ovp = 0v, fst pin open 160 khz v fb = v ovp = 0v, rfst = 200k ? 36 slope compensation s slope slope pin open 1 1.2 1.4 v/s r slope = 200k ? 0.3 0.39 0.47 slope pin output voltage v slope 1 1.1 1.2 v maximum duty cycle d max v fb = 0.15v,fst pin open 95 % minimum on-time t on 100 ns syn input current i syn v syn = 3.3v 400 a v syn = 0v -700 frequency synchronization range ( 5 ) f sw syn r fst >620k ? 0.1 2 mhz pwm dimming off threshold v diml v dim falling 0.6 v pwm dimming on threshold v dimh v dim rising 1.7 v dim input current v dim = 3.3v 36 a v dim = 0v -3.5 pwm dimming frequency 100 50k hz minimum analog dimming threshold v admin v fb = 5mv 0.7 v maximum analog dimming threshold v admax v fb = 200mv 1.5 v en off threshold v enl v en falling 0.6 v en on threshold v enh v en rising 1.7 v en input current i en v en = 3.3v 3.8 a dim gate driver sourcing current i dgd+ v dgd -v ss =10v, v dim =0v -25 ma dim gate driver sinking current i dgd- v dgd -v ss =0v v dim =2v 45 ma
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 5 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. electrical characteristics ( continued ) v vin = 12v, pwm and ad pins floating, r fst =51k ? , t a = +25 c, v vss =v ingnd =0v, unless otherwise noted. parameters symbol condition min typ max units led open ov threshold v ovpth 1.2 v led open ov hysteresis v ovphys 0.1 v led short threshold for immediate latch-off v fbs 600 mv led short delay for latch-off t d_fbs 300mv < v fbs < 600mv 480 s thermal shutdown 150 c thermal shutdown hysteresis 20 c note: 5) guaranteed by design.
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 6 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. pin functions pin # soic16 pin # tssop 16-ep name description 2 1 vin positive voltage input pin. a decoupling cap is needed to prevent large voltage spikes from appearing at the input. 1 2 fault fault condition output, open drain with reference to ingnd. fault is high-z during normal operation, and pulled to ingnd when short led protection is triggered. 3 3 ingnd input ground reference. this pi n is the reference for the en/dim signal. 4 4 syn frequency synchronization input pin. the switching frequency can be synchronized with an exte rnal clock, which frequency is higher than the set frequency with fst resistor. multiple ics? frequencies can also be synchronized without the external clock by connecting all syn pins together. they follow the highest set frequency. 5 5 dim pwm dimming and analog dimming input pin. for digital dimming, apply a 100hz to 50khz square wave signal with amplitude greater than 1.5v to dim pin. for analog dimming, apply a voltage between 0.7v and 1.5v to dim pin. when dim voltage changes from 0.7v to 1.5v, the internal reference for fb regulation changes from 0 to 200mv. a voltage higher than 1.5v at this pin doesn?t modify the internal reference anymore. for combined pwm and analog dimming to get a further high dimming ratio, apply a 100hz to 50khz square wave signal wi th amplitude from 0.7v to 1.5v to dim pin. dim pin voltage is high (about 3.3v) if it is floating. 6 6 en enable input pin. a voltage greater than 0.6v will turn on the chip. 7 7 fst frequency setting pin. a resistor fr om fst to vss setting the switching frequency if there is no syn input. if left open, switching frequency will be set to internal default value. 8 8 slope programmable slope compensation pin. connect a resistor from slope pin to vss sets slope compensati on peak amplitude. if left open, slope compensation will be set internal default value. 9 9 ocp over current protection pin. connect a resistor r ocp from ocp pin to vss sets the cycle-by-cycle current limit of the in side power fet. if left open, the current limit is the default value of 2.5a. 10 10 comp output of error amplifier. connect a 1nf or larger capacitor on comp pin to vss to improve the stability and to provi de a soft on at start up or pwm dimming. 11 11 fb led current feedback input. MP4601 regul ates the voltage across the current sensing resistor between fb and vss with 200mv. if fb voltage is higher than 300mv for 480us or fb voltage is higher than 600mv, it triggers the led short protection. 12 12 ovp over voltage protection pin. use one ex ternal resistor voltage divider across ingnd and vss to program ovp threshold. its voltage is referred to vss. when the ovp pin voltage reaches 1.2v threshold, the switch is turned off and will recover when ovp voltage decreases below 1.1v. when the ovp pin voltage is lower than 0.4v and fb pin voltage is lower than 0.1v, the chip frequency will be folded back. program t he ovp pin voltage from 0.4v to 1.2v for normal operation.
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 7 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. pin functions (continued) pin # soic16 pin # tssop 16-ep name description 13 13 dgd led dimming switch gate drive output pin. 14 14 vss negative voltage output pin. this pin is the voltage reference for ovp, fb, comp, sc, dgd and fst pins. this node should be placed away from switching noise sources. 15 15 sw switch output. sw is the source of the internal mosfet switch. connect to the power inductor and cathode of the schottky rectifier. 16 16 bst bootstrap. a capacitor is connected between sw and bst pins to form a floating supply across the power switch driver.
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 8 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics v in =12v, v out =20v, i led =200ma, fpwm=200hz, ovp point=25v, t a =+25c, unless otherwise noted. analog dimming curve efficiency (%) v in (v) efficiency vs. v in 0 0.2 0.4 0.6 0.8 1 51525354555 pwm dimming curve 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 pwm dimming duty 0 20 40 60 80 100 120 140 160 180 200 0.6 0.8 1 1.2 1.4 1.6 analog dimming voltage (v)
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 9 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics (continued) v in =12v, v out =20v, i led =200ma, fpwm=200hz, ovp point=25v, t a =+25c, unless otherwise noted. v sw 20v/div. v out 20v/div. i led 200ma/div. i l 500ma/div. v sw 20v/div. v out 20v/div. i led 100ma/div. i l 500ma/div. v sw 20v/div. v out 20v/div. i led 100ma/div. i l 1a/div. v sw 20v/div. v pwm 5v/div. i led 200ma/div. i l 1a/div. v sw 20v/div. v en 2v/div. i led 200ma/div. i l 1a/div. v sw 20v/div. v en 2v/div. i led 200ma/div. i l 1a/div. v sw 10v/div. v in 10v/div. i short 2a/div. i l 1a/div. steady state 2 m s/div. pwm dimming 1m s/div. en on en off 2 m s/div. ovp 1 m s/div. short led+ to led- (short recover) short led+ to vss
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 10 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. block diagram figure 1?functional block diagram
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 11 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. operation the MP4601 is a current mode regulator. the sensing resistor senses the led current and feeds it back to an error amplifier, which regulates it to 200mv 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. led open protection if the led is open, there is no voltage on the fb pin. the duty cycle will increase until v ovp - v vss reaches the shutdown threshold. the top switch will turn off until the voltage v ovp -v vss decreases sufficiently. system enjoys auto- recovery for the led open protection. led short protection if the fb voltage is higher than 600mv, immediately ic is latched off and dgd is pulled low. if fb voltage is higher than 300mv for 480 s, ic is also latched off and dgd is pulled low. the en needs reset to restart the ic. the fault pin is pulled low when ic is latched off. dimming control the MP4601 allows both analog and pwm dimming. for analog dimming, when the voltage on dim is from 0.7v to1.5v, the led current will change from 0% to 100% of the maximum led current. if the voltage on dim pin is higher than 1.5v or dim pin is floated, maximum led current will be generated. for pwm dimming, a pwm signal with 100hz to 50khz frequency, amplitude over 1.5v should be applied to dim pin. for combined pwm and analog dimming to get a further high dimming ratio, apply a 100hz to 50khz pwm signal with its amplitude from 0.7v to 1.5v to dim pin. dim pin floated will deliver the maximum led current. at pwm dimming off interval, an internal switch disconnects the comp pin capacitor from the output of the error amplifier. therefore, the comp voltage is hold at pwm off interval. this feature improves the response speed of the led current and helps to achieve high dimming ratio. digital dimming can achieve over 1:1000 dimming ratio with dim frequency less than 200hz.
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 12 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. application information MP4601 is a buck-boost mode led driver. its novel power leverage control technology provides a high efficiency, low cost solution for tv led driver. with a high bus voltage v inh and a low supply voltage v inl (typical 12v or 24v, not recommend higher than 60v), MP4601 can drive over 60 inch or larger size panel for over 350v led string voltage. setting the led current an external resistor r fb is used to set the maximum led current through the use of the equation: fb led 0.200v r i = setting the switching frequency an external resistor r fst can be used to set the switching frequency f s through the use of the equation: s fst 60k f0.95mhz r =? the equation is effective only for 200khz to 2mhz frequency programming range. if fst pin is floating or r fst is larger than 500k ? , the setting frequency is the default value 0.95mhz. setting the current limit an external resistor r ocp can be used to set the cycle-to-cycle current limit i lim through the use of the equation: lim ocp 100k i4.1a 1.1a r =? ? the equation is effective only for a range from 30k to 500k for the programming resistor r ocp . if ocp pin is floating or r ocp is larger than 500k ? , the current limit is the default value of 2.5a. setting the slope compensation MP4601 employs peak current mode control, which will need slope compensation to avoid sub-harmonic oscillation when duty cycle exceeds 50%. the current loop has effective sense resistor of 0.4 ? . given a desired input, output voltage relationship, one can estimate the sense current ramp down slope as: l down v s0.4 l =? v/s where vl is the voltage across the inductor, and l is the inductor value. to ensure current loop stability, a compensation slope of at least half of the ramp down slope is needed: sc down 1 ss 2 >= an external resistor r slope can be used to set the slope compensation for the current loop through the use of the equation: sc slope 60k v s1.2 s r =? the equation is effective only for a range from 20k to 500k for the programming resistor r slope . if slope pin is floating or r slope is larger than 500k ? , the slope compensation is set to default value of 1.2v/s. fault condition output MP4601 has an open drain output to indicate fault condition. during normal operation, fault is high-z output and user can pull it up to any desired voltage with an external resistor. however, if for some reason, fb is greater than 600mv above vss, or fb is greater than 300mv above vss for a pre-determined time of ~480 s, fault will be pulled low to ingnd level. the rdson for this pull down switch is ~100 ? . 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: in out sin out l vv l f(v v ) i ? = ? +??
MP4601 ? white led driver for la rge size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 13 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. 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: out l _ avg led in v ii(1) v =?+ . make sure the inductor is not saturated at the maximum peak current, which is: l_pk l_avg l ii 0.5i =+?? . 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_avg out in sininout iv c fv(vv) ? > ?? ? + 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. led out out soutinout iv c fv (vv) ? > ?? ? + pc board layout the high current paths (vss, vdd and sw) should be placed 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.
MP4601 ? white led driver for large size backlighting MP4601 rev. 1.0 www.monolithicpower.com 14 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical application circuits fault ingnd vin syn vss ovp dgd fb com sw bst ocp rsc 60k rocp 100k dim en fst slope figure 2?white led driver application for tv applications
MP4601 ? white led driver for large size tv backlighting MP4601 rev. 1.0 www.monolithicpower.com 15 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. package information tssop16-ep note: 1) all dimensions are in millimeters. 2) package length does not include mold flash, protrusion or gate burr. 3) package width does not include interlead flash or protrusion. 4) lead coplanarity (bottom of leads after forming) shall be 0.10 millimeters max. 5) drawing conforms to je dec mo-153, variation abt. 6) drawing is not to scale. 0.19 0.30 4.90 5.10 seating plane 0.65 bsc pin 1 id 4.30 4.50 6.20 6.60 18 9 16 0.80 1.05 1.20 max 0.00 0.15 top view front view side view 0.09 0.20 recommended land pattern 5.80 typ 1.60 typ 0.40 typ 0.65 bsc 2.80 typ 3.30 typ detail a 0.45 0.75 0 o -8 o 0.25 bsc gauge plane see detail "a"
MP4601 ? white led driver for la rge size 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. MP4601 rev. 1.0 www.monolithicpower.com 16 1/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. soic16 0.016(0.41) 0.050(1.27) 0 o -8 o detail "a" 0.010(0.25) 0.020(0.50) x 45 o see detail "a" 0.0075(0.19) 0.0098(0.25) 0.150 (3.80) 0.157 (4.00) pin 1 id 0.050(1.27) bsc 0.013(0.33) 0.020(0.51) seating plane 0.004(0.10) 0.010(0.25) 0.386( 9.80) 0.394(10.00) 0.053(1.35) 0.069(1.75) top view front view 0.228 (5.80) 0.244 (6.20) side view 1 8 16 9 recommended land pattern 0.213 (5.40) 0.063 (1.60) 0.050(1.27) 0.024(0.61) note: 1) control dimension is in inches. dimension in bracket is in millimeters. 2) package length does not include mold flash, protrusions or gate burrs. 3) package width does not include interlead flash or protrusions. 4) lead coplanarity (bottom of leads after forming) shall be 0.004" inches max. 5) drawing conforms to jedec ms-012, variation ac. 6) drawing is not to scale. 0.010(0.25) bsc gauge plane

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