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general description the MAX16823 three-channel led driver operates from a 5.5v to 40v input voltage range and delivers up to 70ma per channel to one or more strings of high-brightness leds (hbleds). each channel? current is programmable using an external current-sense resistor in series with the leds. three dim inputs allow a wide range of indepen- dent pulsed dimming in addition to providing the on and off control of the outputs. wave-shaping circuitry reduces emi while providing fast turn-on and turn-off times. the MAX16823 is well suited for automotive applications requiring a high-voltage input and is able to withstand load-dump events up to 45v. on-board pass elements minimize external components while providing 5% led current accuracy. additional features include an active- high, open-drain ledgood output for open led detec- tion, a +3.4v (?%) regulated output with 4ma output current capability, short-circuit and thermal protections. the MAX16823 is available in thermally enhanced 5mm x 5mm, 16-pin tqfn-ep and 16?in tssop-ep packages and is specified over the -40? to +125? automotive temperature range. applications automotive exterior: rear combination lights (rcls), chmsl automotive interior: rgb ambient lighting, cluster lighting, and lcd backlighting emergency vehicle warning lights navigation and marine indicators architectural and industrial lighting features 5.5v to 40v operating range adjustable constant output current (5ma to 70ma and up to 2a with external bjt) ?% output current accuracy open led detection three independent high-voltage dim inputs three integrated pass elements with low dropout voltage (0.7v max) undervoltage lockout output short-circuit protection 3.4v voltage regulator with 4ma capability accurate, low 203mv current sense overtemperature shutdown -40? to +125? operating temperature range MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection ________________________________________________________________ maxim integrated products 1 cs1 cs2 cs3 out3 cs1 cs2 cs3 gnd ledgood dim2 dim1 v in c in in in in r ledgood c lgc reg c reg lgc dim3 reg out2 out1 MAX16823 ordering information typical operating circuit 19-0733; rev 1; 3/07 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. pin configurations appear at end of data sheet. evaluation kit available part temp range pin- package pkg code MAX16823ate+ -40? to +125? 16 tqfn-ep* t1655-3 MAX16823aue+ -40? to +125? 16 tssop-ep* u16e-3 + denotes a lead-free package. * ep = exposed pad.
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = 12v, c reg = 0.1?, i reg = 0, c lgc = 15nf, v dim1 = v dim2 = v dim3 = 3.4v, r cs_ = 2.85 from cs_ to gnd, t j = t a = -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. parameter symbol conditions min typ max units supply voltage range v in 5.5 40 v v in rising 4.4 4.9 5.4 undervoltage lockout uvlo v in falling 4.0 4.6 5.2 v ground current i g i out1 = i out2 = i out3 = 70ma 1.5 3 ma guaranteed output current i out 70 ma led current-sense accuracy 5ma i out_ 70ma 5 % i out_ = 70ma, 6.5v v in 40v 0.3 0.7 dropout voltage (note 2) vdo i out_ = 70ma, 5.5v v in 6.5v 0.3 0.8 v output current slew rate 8 ma/? short-circuit current v out_ = 0v 180 ma ledgood ledgood output logic low v ol i sink = 2ma 0.4 v lgc pullup resistor 65 100 135 k lgc input upper threshold v uth 2.53 v lgc input lower threshold v lth 0.8 v lgc pulldown current v lgc > v uth 20 ma lgc clock period c lgc = 15nf 0.77 1.5 2.3 ms dimming input (dim1, dim2, dim3) dim_ logic-input bias current i dim_ -0.1 +0.1 a dim_ input-voltage high 2.4 v in v dim_ input-voltage low 0.6 v dim_ frequency 0 3 khz outputs (out1, out2, and out3) (note 3) turn-on time dim_ rising edge to 90% of out_ current 12 28 ? turn-off time dim_ falling edge to 10% of out_ current 8 18 s output current rise time 10% to 90% 7 18 s output current fall time 90% to 10% 6 15 s in to gnd ...............................................................-0.3v to +45v out1, out2, out3, dim1, dim2, dim3 to gnd ...........................................-0.3v to (v in + 0.3v) reg, lgc, ledgood to gnd ................................-0.3v to +6v cs1, cs2, cs3 to gnd .........................................-0.3v to +0.5v out1, out2, out3 short circuited to gnd duration (v in + 16v) ..........................................60min maximum current into any pin (except in, out1, out2, out3)..................................?0ma continuous power dissipation (t a = +70?) 16-pin tqfn 5mm x 5mm (derate 33.3mw/? above +70?) .........................2666mw 16-pin tssop (derate 26.1mw/? above +70?) ....2088.8mw operating temperature range .........................-40? to +125? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300?
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection _______________________________________________________________________________________ 3 note 1: all devices 100% production tested at t j = +25?. limits over the operating temperature range are guaranteed by design. note 2: dropout is measured as follows: connect a resistor from out_ to cs_. connect r cs_ = 2.85 ? from cs_ to gnd. set v in = v out + 3v (record v out as v outa ). reduce v in until v out = 0.97 x v outa (record as v inb and v outb ). vdo = v inb - v outb . note 3: output current rise and fall times are measured with a 62 ? series resistor from out_ to cs_. note 4: overtemperature protection does not function if the output of the 3.4v reference (reg) is shorted to ground. parameter symbol conditions min typ max units current sense regulated cs_ voltage v cs_ 5ma i out _ 70ma 193 203 213 mv input current (cs1, cs2, cs3) current out of cs_ +1.2 a overtemperature protection (note 4) thermal shutdown temperature 155 ? thermal shutdown hysteresis 23 ? 3.4v regulator (reg) 3.275 3.41 3.547 output voltage v reg 0 i reg 4ma 3.221 3.38 3.547 v reg short-circuit current v reg = 0v 13 ma electrical characteristics (continued) (v in = 12v, c reg = 0.1?, i reg = 0, c lgc = 15nf, v dim1 = v dim2 = v dim3 = 3.4v, r cs_ = 2.85 from cs_ to gnd, t j = t a = -40? to +125?, unless otherwise noted. typical values are at t a = +25?.) (note 1) typical operating characteristics (v in = 12v, c reg = 0.1?, i reg = 0, v lgc = unconnected, connect r cs_ = 2.85 from cs_ to gnd. connect out_ to cs_ through a resistor, t j = -40? to +125?, unless otherwise noted. typical values are at t a = +25?.) v cs_ vs. output current output current (ma) v cs_ (v) MAX16823 toc02 0 10203040506070 0.200 0.201 0.202 0.203 0.204 0.205 0.206 0.207 0.208 0.209 0.210 output current vs. input voltage input voltage (v) output current (ma) MAX16823 toc03 0 5 10 15 20 25 30 35 40 0 10 20 30 40 50 60 70 80 90 100 i out = 70ma i out = 5ma output current vs. temperature temperature ( c ) output current (ma) MAX16823 toc01 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 10 20 30 40 50 60 70 80 90 100 i load = 5ma i load = 35ma i load = 70ma
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 4 _______________________________________________________________________________________ supply current vs. temperature temperature ( c) supply current (ma) MAX16823 toc05 -40-25-105 203550658095110125 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 v in = 5.5v v in = 12v v in = 20v v in = 40v v dim1 = v dim2 = v dim3 = 0v v reg vs. temperature temperature ( c) v reg (v) MAX16823 toc06 -40 -25 -10 5 20 35 50 65 80 95 110 125 3.0 3.1 3.2 3.3 3.4 3.5 i load = 4ma i load = 1ma i load = 0 v cs_ vs. i reg i reg (ma) v cs_ (v) MAX16823 toc07 012345678910 0.195 0.196 0.197 0.198 0.199 0.200 0.201 0.202 0.203 0.204 0.205 0.206 0.207 0.208 0.209 0.210 i load = 70ma v reg vs. v in v in (v) v reg (v) MAX16823 toc08 0 5 10 15 20 25 30 35 40 3.35 3.36 3.37 3.38 3.39 3.40 3.41 3.42 3.43 3.44 3.45 i reg = 0 i reg = 1ma i reg = 4ma 330hz dimmed operation MAX16823 toc09 20 s/div v dim 2v/div 0v 0a i led 50ma/div v in = 12v, dim pulsed at 33hz (1% duty cycle) i load = 70ma 200hz dimmed operation (expanded) MAX16823 toc10 10 s/div v dim 2v/div 0v 0a i load 50ma/div v in = 12v, dim pulsed at 200hz (50% duty cycle) i load = 70ma 200hz dimmed operation (expanded) MAX16823 toc11 10 s/div v dim 2v/div 0v 0a i load 50ma/div v in = 12v, dim pulsed at 200hz (50% duty cycle) i load = 70ma dropout voltage vs. temperature temperature ( c) dropout voltage (mv) MAX16823 toc04 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 i load = 70ma typical operating characteristics (continued) (v in = 12v, c reg = 0.1?, i reg = 0, v lgc = unconnected, connect r cs_ = 2.85 from cs_ to gnd. connect out_ to cs_ through a resistor, t j = -40? to +125?, unless otherwise noted. typical values are at t a = +25?.) ledgood response times MAX16823 toc12 2ms/div v dim v ledgood 5v/div 5v/div 0v 0v 0v v lgc 5v/div v in = 12v c lgc = 15nf
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection _______________________________________________________________________________________ 5 pin description pin tqfn tssop name function 1 3 dim1 d i m m i ng inp ut 1. d im 1 i s a l ow - fr eq uency d i m m i ng i np ut for channel 1. a l og i c- l ow tur ns off o u t1 and a l og i c- hi g h tur ns on o u t1. 2 4 dim2 d i m m i ng inp ut 2. d im 2 i s a l ow - fr eq uency d i m m i ng i np ut for channel 2. a l og i c- l ow tur ns off o u t2 and a l og i c- hi g h tur ns on o u t2. 3 5 dim3 d i m m i ng inp ut 3. d im 3 i s a l ow - fr eq uency d i m m i ng i np ut for channel 3. a l og i c- l ow tur ns off o u t3 and a l og i c- hi g h tur ns on o u t3. 4 6 ledgood open led output. ledgood is an open-drain output. a logic-high indicates the led connection i s g ood i n al l thr ee channel s. a l og i c- l ow i nd i cates an op en le d connecti on. s ee the le d go od secti on. 5, 6, 7 7, 8, 9 in p osi ti ve inp ut s up p l y. byp ass w i th a 0.1f ( m i n) cap aci tor to g n d . c onnect al l in p i ns tog ether . 810lgc le d d etecti on- ti m i ng s etti ng . c onnect a cap aci tor fr om lgc to g r ound to set the d el ay ti m e for le d g oo d . 9 11 reg 3.4v v ol tag e reg ul ator . c onnect a 0.1f cap aci tor fr om re g to g n d . 10 12 gnd g r ound 11 13 cs3 c hannel 3 s ense am p l i fi er p osi ti ve inp ut. c onnect the cur r ent- sense r esi stor b etw een c s 3 and g n d to p r og r am the outp ut cur r ent l evel for channel 3. 12 14 cs2 c hannel 2 s ense am p l i fi er p osi ti ve inp ut. c onnect the cur r ent- sense r esi stor b etw een c s 2 and g n d to p r og r am the outp ut cur r ent l evel for channel 2. 13 15 cs1 c hannel 1 s ense am p l i fi er p osi ti ve inp ut. c onnect the cur r ent- sense r esi stor b etw een c s 1 and g n d to p r og r am the outp ut cur r ent l evel for channel 1. 14 16 out3 c ur r ent reg ul ator o utp ut 3 15 1 out2 c ur r ent reg ul ator o utp ut 2 16 2 out1 c ur r ent reg ul ator o utp ut 1 ep ep ep e xp osed p ad . c onnect e p to a l ar g e- ar ea g r ound p l ane for effecti ve p ow er d i ssi p ati on. d o not use as the ic g r ound connecti on.
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 6 _______________________________________________________________________________________ detailed description the MAX16823 three-channel current regulator operates from a 5.5v to 40v input voltage range and delivers up to 70ma per channel to one or more strings of hbleds. the output currents are programmable using external current-sense resistors in series with the leds. three dim inputs allow a wide range of independent pulsed dimming in addition to providing the on and off control of the outputs. the MAX16823 offers an ledgood output that indicates an open-circuit condition when one or more led channels are open. integrated pass elements minimize external compo- nents while providing 5% output current accuracy. additional features include a 3.4v (?%) voltage regula- tor with 4ma output current capability, short-circuit and thermal protection. the MAX16823 uses a feedback loop to linearly control the current from each output. the voltage across each sense resistor is compared to a fixed reference voltage and the error is amplified to drive the internal power pass device for a particular channel. see the block diagram . the regulation point is factory-set at 203mv. the regulated current is adjusted by the value of r cs__ . the MAX16823 is a constant-current led driver inter- nally optimized for driving the impedance range expected from one or more hbleds. 3.4v regulator (reg) the MAX16823 includes a fixed 3.4v voltage regulator that delivers up to 4ma of load current for auxiliary applications throughout the 5.5v to 40v input voltage range. connect a 0.1? compensation capacitor from reg to ground. shorting reg to ground disables the thermal shutdown. thermal protection the MAX16823 enters a thermal-shutdown mode in the event of overheating. this typically occurs in overload or output short-circuit conditions. when the junction temper- ature exceeds t j = +155?, the internal thermal protec- tion circuitry turns off the series pass elements. the MAX16823 recovers from thermal-shutdown mode once the junction temperature drops by 23?. the part will therefore protect itself by low-frequency thermal cycling in the event of a short-circuit or overload condition. applications information programming the led current the MAX16823 uses sense resistors to set the output current for each channel. to set the led current for a particular channel, connect a sense resistor across the corresponding current-sense input (cs_) and gnd. for optimal accuracy, connect the low-side of the current- sense resistors to the ic? ground pin with short traces. the value needed for the sense resistor for a given cur- rent can be calculated with the equation below: where v cs_ is 203mv and i out_ is the desired led current (i led ). input-voltage considerations for proper operation, the minimum input voltage must always be: where v ft(max) is the total forward voltage of all series- connected leds. the minimum operating voltage of the device is 5.5v. ledgood the MAX16823 features an active-low, open-drain ledgood output that goes low either when one or more led channels are open or when a signal at any of the dimming inputs remains low for a period greater than the programmed ledgood delay time t delay . program t delay with a capacitor connected between lgc and ground. the ledgood output goes low after the programmed delay period t delay has elapsed. use the following formula to set the delay period: where c lgc is the capacitor connected between lgc and ground. the ledgood output goes low during the thermal shutdown. tcf delay lgc = 257 900 ,() () vv v v in min cs max ft max do max ( ) _( ) ( ) ( ) ++ r vv ia cs cs out _ _ _ () () () =
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection _______________________________________________________________________________________ 7 pulse-dimming inputs (dim_) the MAX16823 features pulsed or chopped-current dimming inputs (dim_) to chop the led current and to adjust the brightness. dim_ also serves as an active- high enable input. a logic-low at dim_ turns off out_ and a logic-high turns on out_. if the signal at dim stays low more than the programmed ledgood delay time, ledgood goes low (figure 1). two brightness levels for tail/stop lights figure 2 shows the pwm dimming operation for the MAX16823 with an icm7555 timer. the icm7555 pro- vides an adjustable duty cycle using two external resis- tors and a capacitor. in tail operation, the output of the icm7555 feeds into dim and lights up the leds. the led? brightness depends on the duty cycle of the i_reg MAX16823 i_reg i_reg in in in out1 cs1 out2 out3 uvlo thermal shutdown lgc ledggood dim3 dim2 dim1 gnd in in in bandgap ledgood detector cs2 cs3 reg block diagram
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 8 _______________________________________________________________________________________ icm7555. when v stop is present, dim is pulled up to v stop . the pwm dimming operation is disabled and the leds light up to full brightness. see the icm7555 data sheet for formulas to calculate the dimming fre- quency and the duty cycle. outputs latch-off figure 3 shows a circuit with dim1, dim2, dim3, and ledgood connected through a resistor to v reg . this circuit is useful for applications that require all outputs to latch off when one of the leds opens. the MAX16823 resumes current regulation again through power cycling, once the fault condition is removed. other applications the application circuit in figure 4 implements a two- level brightness current for tail/stop lights. in tail operation, q1 is off and r cs1 sets the output current. in stop operation, q1 turns on and the output current is set by a parallel combination of r cs1 and r2. figure 5 shows an application circuit with the MAX16823 using a single bjt to provide high output current. for proper operation: for minimized dropout, the leds can be placed in the collector. vv v vv in min be max ft max cs do max () () () _ () >+++ dim t on ledgood ledgood goes low when t off > t delay t off figure 1. ledgood timing delay in dim2 cs1 reg out1 gnd r cs1 r cs2 r cs3 leds 0.1 f th trg gnd out in dis icm7555 r3 c2 r2 r1 d1 d4 c1 d2 d3 tail stop dim1 dim3 out2 out3 cs2 cs3 MAX16823 100k figure 2. pwm dimming operation with icm7555
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection _______________________________________________________________________________________ 9 in dim3 dim2 cs1 out1 gnd r cs1 r cs2 r cs3 leds leds leds c in c reg v in dim1 v reg ledgood reg out2 out3 cs2 cs3 MAX16823 r1 figure 3. output_ latch-off in dim3 dim2 cs1 out1 gnd r cs1 r cs2 r cs3 leds r2 r3 q1 leds leds dim1 stop tail c in out2 out3 cs2 cs3 MAX16823 reg c reg d1 d2 stop/tail tail tail *r1 = 100k r1* figure 4. two-brightness level with current level switch for tail/stop lights
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 10 ______________________________________________________________________________________ preload current figure 6 shows the MAX16823 with a preload circuit. in the circuit, the bjt, r preload , and reg generate a preset load current. the preset load current i preset is determined with the following formula: this circuit is used with older body controllers that monitor minimum rcl current to detect failures. i vv r preset reg preload = ? 07 . in dim_ gnd r cs_ leds q1 c in v in out_ cs_ MAX16823 reg c2 pwm dimming figure 5. increased led current (amper range) with a single bjt r cs1 r cs2 r cs3 out3 cs1 cs2 cs3 gnd dim2 dim1 stop tail in in in c in r preload c lgc c reg lgc dim3 reg out2 out1 MAX16823 tail tail stop 100k 100k figure 6. preload current setting
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection ______________________________________________________________________________________ 11 chip information process: bicmos-dmos pin configurations 15 16 14 13 6 5 7 dim2 ledgood 8 dim1 cs3 reg cs2 12 out3 4 12 11 9 out2 out1 lgc in in in *ep MAX16823 dim3 gnd 3 10 cs1 tqfn + top view 16 15 14 13 12 11 10 1 2 3 4 5 6 7 out3 cs1 cs2 cs3 dim2 dim1 out1 out2 top view *ep = exposed pad. MAX16823 gnd reg lgc in ledgood 9 8in in dim3 tssop + *ep
qfn thin.eps MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 12 ______________________________________________________________________________________ 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 .)
MAX16823 high-voltage, 3-channel linear high-brightness led driver with open led detection 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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 13 2007 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 .) tssop 4.4mm body.eps e 1 1 21-0108 package outline, tssop, 4.40 mm body, exposed pad xx xx revision history pages changed at rev 1: 1, 13

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