general description the max16819/MAX16820, step-down constant-current high-brightness led (hb led) drivers provide a cost- effective solution for automotive interior/exterior lighting, architectural and ambient lighting, led bulbs such as mr16 and other led illumination applications. the max16819/MAX16820 operate from a 4.5v to 28v input voltage range and feature a 5v/10ma on-board regulator. a high-side current-sense resistor adjusts the output current and a dedicated pwm input (dim) enables a wide range of pulsed dimming. the max16819/MAX16820 are well suited for applica- tions requiring a wide input voltage range. the high-side current-sensing and an integrated current-setting circuit- ry minimize the number of external components while delivering an led current with ?% accuracy. a hys- teretic control algorithm ensures excellent input-supply rejection and fast response during load transients and pwm dimming. the max16819 features a 30% inductor current ripple and the MAX16820 features a 10% current ripple. these devices operate up to 2mhz switching fre- quency, thus allowing for small component size. the max16819/MAX16820 operate over the -40? to +125? automotive temperature range and are avail- able in 3mm x 3mm x 0.8mm, 6-pin tdfn packages. applications architectural, industrial, and ambient lighting automotive rcl, drl, and fog lights mr16 and other led bulbs indicators and emergency lighting features ? high-side current sense ? dedicated dimming control input ? 20khz maximum dimming efficiency ? hysteretic control: no compensation ? up to 2mhz switching frequency ? ?% led current accuracy ? adjustable constant led current ? 4.5v to 28v input voltage range ? over 25w output power ? 5v, 10ma on-board regulator ? -40? to +125? operating temperature range note: all devices are specified over the -40? to +125? oper- ating temperature range. + denotes lead-free package. * ep = exposed paddle. max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming ________________________________________________________________ maxim integrated products 1 1 + 23 654 dim csn in gnd drv v cc max16819 MAX16820 tdfn top view part pin-package pkg code top mark max16819 att+t 6 tdfn?p* t633-2 +atb MAX16820 att+t 6 tdfn-ep* t633-2 +atc pin configuration ordering information max16819 MAX16820 in csn dim v cc c in drv gnd c vcc v in l r sense typical operating circuit 19-0706; rev 0; 12/06 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com.
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = 12v, v dim = v in , c vcc = 1?, r sense = 0.5 ? , t a = t j = -40? to +125?, unless otherwise noted. typical values are at t a = +25?.) (note 1) stresses beyond those listed under ?bsolute maximum 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 conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in, csn, dim to gnd .............................................-0.3v to +30v v cc , drv to gnd ....................................................-0.3v to +6v csn to in...............................................................-0.3v to +0.3v maximum current into any pin (except in, v cc , and drv)............................................?0ma continuous power dissipation (t a = +70?) 6-pin tdfn (derate 18.17mw/ o c * above +70?).......1454mw operating temperature range .........................-40? to +125? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? pin-to-pin esd ratings (hb model).....................................2.5kv *as per jedec51 standard (single-layer board). parameter symbol conditions min typ max units input voltage range v in 4.5 28.0 v maximum current regulator switching frequency f sw 2 mhz ground current i gnd drv open 1.5 ma supply current i in v dim < 0.6v 425 ? v in = v csn = v dim , v in rising from 4v until v drv > v cc - 0.5v 4.7 5.0 undervoltage lockout uvlo v in = v csn = v dim , v in falling from 6v, v drv < 0.5v 4.5 v undervoltage lockout hysteresis 0.5 v sense comparator (v in - v csn ) rising from 0v until v drv < 0.5v (MAX16820) 195 210 225 sense voltage threshold high v snshi (v in - v csn ) rising from 0v until v drv < 0.5v (max16819) 213 230 246 mv (v in - v csn ) falling from 0.26v until v drv > (v cc - 0.5v) (MAX16820) 176 190 204 sense voltage threshold low v snslo (v in - v csn ) falling from 0.26v until v drv > (v cc - 0.5v) (max16819) 158 170 182 mv propagation delay to output high t dpdh falling edge of (v in - v csn ) from 0.26v to 0v to drv high, c drv = 1nf 82 ns propagation delay to output low t dpdl rising edge of (v in - v csn ) from 0v to 0.26v to drv low, c drv = 1nf 82 ns current-sense input current i csn (v in - v csn ) = 200mv 1 a max16819 56 70 mv current-sense threshold hysteresis cs hys MAX16820 17 35 mv
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming _______________________________________________________________________________________ 3 parameter symbol conditions min typ max units gate driver gate driver source current v csn = v in , v drv = 0.5 x v cc 0.5 a gate driver sink current v csn = v in - 250mv, v drv = 0.5 x v cc 1a gate driver output-voltage high v oh i drv = 10ma v cc - 0.5 v gate driver output-voltage low v ol i drv = -10ma 0.5 v dim input maximum dim frequency f dim 20 khz dim input-voltage high v ih v csn = v in , increase dim until v drv > (v cc - 0.5v) 2.8 v dim input-voltage low v il v csn = v in , decrease dim until v drv < 0.5v 0.6 v dim hysteresis dim hys 200 mv dim turn-on time t dimon dim rising edge to v drv = 0.5 x v cc , c drv = 1nf 100 ns dim turn-off time t dimoff dim falling edge to v drv = 0.5 x v cc , c drv = 1nf 100 ns dim input leakage high v dim = v in 10 ? dim input leakage low v dim = 0v -1 +1 ? v cc regulator i vcc = 0.1ma to 10ma, v in = 5.5v to 28v 4.5 5.5 v regulator output voltage v cc i vcc = 0.1ma to 10ma, v in = 4.5v to 28v 4.0 5.5 v load regulation i vcc = 0.1ma to 10ma, v in = 12v 4 ? line regulation v in = 6v to 28v, i vcc = 10ma 11 mv power-supply rejection ratio psrr v in = 12v, i vcc = 5ma, f in = 10khz -35 db v in = 4.5v, v cc = 0v 45 ma current limit i lim v in = 4.5v, v cc = 4v 18 ma regulator startup time t strat v cc = 0 to 4.5v 350 ? electrical characteristics (continued) (v in = 12v, v dim = v in , c vcc = 1?, r sense = 0.5 ? , t a = t j = -40? to +125?, unless otherwise noted. typical values are at t a = +25?.) (note 1) note 1: all devices are 100% production tested at t j = +25? and +125?. limits to -40? are guaranteed by design.
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming 4 _______________________________________________________________________________________ typical operating characteristics (v in = v dim = 12v, c vcc = 1?, r sense = 0.5 ? connected between in and csn. typical values at t a = +25?, unless otherwise noted.) efficiency vs. v in max16819 toc01 v in (v) efficiency (%) 25 20 10 15 65 70 75 80 90 85 95 100 60 530 led 5 led 4 led 3 led 2 led 1 l = 47 h drv switching frequency vs. v in max16819 toc02 v in (v) drv switching frequency (khz) 24 20 16 12 8 100 200 300 400 600 500 700 800 900 1000 1100 1200 1300 1400 1500 0 428 l = 47 h led 5 led 4 led 3 led 1 led 2 led current variation vs. v in max16819 toc03 v in (v) led current variation from set current (%) 25 20 10 15 -1.5 -1.0 -0.5 0 1.0 0.5 1.5 2.0 -2.0 530 led 5 led 4 led 3 led 2 led 1 i led(nominal) = 400ma l = 47 h v cc vs. v in max16819 toc04 v in (v) v cc (v) 25.0 22.5 17.5 20.0 10.0 12.5 15.0 7.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 4.5 5.0 27.5 i led = 0 v cc vs. temperature max16819 toc05 temperature ( c) v cc (v) 110 95 65 80 -10 5 20 35 50 -25 5.31 5.32 5.33 5.34 5.35 5.36 5.37 5.38 5.39 5.40 5.30 -40 125 v in = 24v v in = 12v v dim = 0v supply current vs. v in max16819 toc06 v in (v) supply current ( a) 24.5 12.5 20.5 16.5 8.5 50 100 150 200 250 300 0 4.5 28.5 v dim = 0v pwm dimming at 200hz (10% duty cycle) max16819 toc07 1ms/div v dim 2v/div 0v 0a i led 200ma/div v in = 12v, l = 47 h, 1 led max16819 pwm dimming at 200hz (90% duty cycle) max16819 toc08 1ms/div v dim 2v/div 0v 0a i led 200ma/div v in = 12v, l = 47 h, 1 led max16819
max16819/MAX16820 pwm dimming at 20khz (10% duty cycle) max16819 toc12 10 s/div v dim 2v/div 0v 0a i led 200ma/div v in = 24v, l = 47 h, 4 leds MAX16820 pwm dimming at 20khz (90% duty cycle) max16819 toc13 10 s/div v dim 2v/div 0v 0a i led 200ma/div v in = 24v, l = 33 h, 4 leds MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming _______________________________________________________________________________________ 5 pwm dimming at 200hz (1% duty cycle) max16819 toc09 10 s/div v dim 2v/div 0v 0a i led 200ma/div v in = 12v, l = 47 h, 1 led max16819 pwm dimming expanded (50% duty cycle) max16819 toc10 1 s/div v dim 2v/div 0v 0a i led 200ma/div v in = 24v, l = 33 h, 4 leds MAX16820 pwm dimming expanded (50% duty cycle) max16819 toc11 4 s/div v dim 2v/div 0v 0a i led 200ma/div v in = 12v, l = 47 h, 1 led max16819 i led variation vs. temperature max16819 toc14 temperature ( c) led current variation from set current (%) 110 95 -25 -10 5 35 50 65 20 80 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 -2.0 -40 125 v in = 24v v in = 12v v dim = 0v i led(nominal) = 400ma l = 47 h typical operating characteristics (continued) (v in = v dim = 12v, c vcc = 1?, r sense = 0.5 ? connected between in and csn. typical values at t a = +25?, unless otherwise noted.)
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming 6 _______________________________________________________________________________________ max16819 MAX16820 regulator cs comparator uvlo comparator 1.23v bandgap ref gate driver dim buffer v cc drv gnd + - - + csn in dim pin description functional diagram pin name function 1 in positive supply voltage input. bypass with a 1? or higher value capacitor to gnd. 2 csn current-sense input 3 dim logic-level dimming input. drive dim low to turn off the current regulator. drive dim high to enable the current regulator. 4 gnd ground 5 drv gate drive output. connect to the gate of an external n-channel mosfet. 6v cc voltage regulator output. connect a 1? capacitor from v cc to gnd. ep exposed paddle. connect to a large-area ground plane for improved power dissipation. do not use as the only ground connection for the device. detailed description the max16819/MAX16820 are step-down, constant- current, high-brightness led (hb led) drivers. these devices operate from a 4.5v to 28v input voltage range and provide up to 0.5a of source and 1a of sink drive capability to the gate of an external mosfet. a high- side current-sense resistor sets the output current and a dedicated pwm dimming input (dim) allows for a wide range of independent pulsed dimming. the high-side current-sensing scheme and on-board current-setting circuitry minimize the number of exter- nal components while delivering led current with a ?% accuracy, using a 1% sense resistor. see the functional diagram .
undervoltage lockout (uvlo) the max16819/MAX16820 include a 4.5v undervoltage lockout (uvlo) with 500mv hysteresis. when v in falls below 4.5v, drv goes low, turning off the external n-chan- nel mosfet. drv goes high once v in is 5v or higher. 5v regulator v cc is the output of a 5v regulator capable of sourcing 10ma. bypass v cc to gnd with a 1? capacitor. dim input the max16819/MAX16820 allow dimming with a pwm signal at the dim input. a logic level below 0.6v at dim forces the max16819/MAX16820? drv output low, turning off the led current. to turn the led current on, the logic level at dim must be at least 2.8v. applications information selecting r sense to set the led current the max16819/MAX16820 feature a programmable led current using a resistor connected between in and csn. use the following equation to calculate the sense resistor: for the values of v snshi and v snslo, see the electrical characteristics . current regulator operation the max16819/MAX16820 regulate the led output current using an input comparator with hysteresis (figure 1). as the current through the inductor ramps up and the voltage across the sense resistor reaches the upper threshold, the voltage at drv goes low, turn- ing off the external mosfet. the mosfet turns on again when the inductor current ramps down through the freewheeling diode until the voltage across the sense resistor equals the lower threshold. use the fol- lowing equation to determine the operating frequency: where n = number of leds, v led = forward voltage drop of one led, and ? v = (v snshi - v snslo ). for proper component selection, please use the design tool available at: http://www.maxim-ic.com/max16819- 20-too l. f vnv nv r vvl sw in led led sense in = ? () ? r vvv ia sense snshi snslo led ? () = + ()() () 1 2 max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming _______________________________________________________________________________________ 7 hysteretic mode avg. led current 1 f sw t sw = i led t t v dim ? i figure 1. current regulator operation
max16819/MAX16820 mosfet selection the max16819/MAX16820? gate driver is capable of sourcing 0.5a and sinking 1a of current. mosfet selec- tion is based on the maximum input operating voltage v in , output current i led , and operating switching fre- quency. choose a mosfet that has a higher break- down voltage than the maximum operation voltage, low r ds(on) , and low total charge for better efficiency. mosfet threshold voltage must be adequate if operat- ed at the low end of the input-voltage operating range. freewheeling diode selection the forward voltage of the freewheeling diode should be as low as possible for better efficiency. a schottky diode is a good choice as long as the breakdown volt- age is high enough to withstand the maximum operat- ing voltage. the forward current rating of the diode must be at least equal to the maximum led current. led current ripple the led current ripple is equal to the inductor current ripple. in cases when a lower led current ripple is needed, a capacitor can be placed across the led ter- minals. pcb layout guidelines careful pcb layout is critical to achieve low switching losses and stable operation. use a multilayer board whenever possible for better noise immunity. minimize ground noise by connecting high-current ground returns, the input bypass-capacitor ground lead, and the output-filter ground lead to a single point (star ground configuration). in normal operation, there are two power loops. one is formed when the mosfet is on and the high current flows through in? sense leds?nductor?osfet?nd. the other loop is formed when the mosfet is off when the high current circulates through r sense ?eds?nductor?ree- wheeling diode. to minimize noise interaction, each loop area should be as small as possible. place r sense as close as possible to the input filter and in. for better noise immunity, a kelvin connection is strongly recommended between csn and r sense . connect the exposed paddle to a large-area ground plane for improved power dissipation. 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming 8 _______________________________________________________________________________________ chip information process: bicmos
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming _______________________________________________________________________________________ 9 package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) 6, 8, &10l, dfn thin.eps h 1 2 21-0137 package outline, 6,8,10 & 14l, tdfn, exposed pad, 3x3x0.80 mm
max16819/MAX16820 2mhz high-brightness led drivers with high-side current sense and 5000:1 dimming maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2006 maxim integrated products is a registered trademark of maxim integrated products, inc. package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2006 maxim integrated products is a registered trademark of maxim integrated products, inc. common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.300.10 1.500.10 6 t633-1 0.95 bsc mo229 / weea 1.90 ref 0.400.05 1.95 ref 0.300.05 0.65 bsc 2.300.10 8 t833-1 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.05 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.10 1.500.10 mo229 / weec mo229 / weed-3 0.40 bsc - - - - 0.200.05 2.40 ref t1433-2 14 2.300.10 1.700.10 t633-2 6 1.500.10 2.300.10 0.95 bsc mo229 / weea 0.400.05 1.90 ref t833-2 8 1.500.10 2.300.10 0.65 bsc m o229 / weec 0.300.05 1.95 ref t833-3 8 1.500.10 2.300.10 0.65 bsc m o229 / weec 0.300.05 1.95 ref -drawing not to scale- h 2 2 21-0137 package outline, 6,8,10 & 14l, tdfn, exposed pad, 3x3x0.80 mm 2.300.10 mo229 / weed-3 2.00 ref 0.250.05 0.50 bsc 1.500.10 10 t1033-2
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