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general description the MAX16824/max16825 three-channel led drivers operate over a 6.5v to 28v input voltage range. these devices provide three open-drain constant-current-sink- ing outputs that are rated to 36v and deliver up to 150ma of current to each string of high-brightness leds (hb leds). the current at each output is programmable by means of an external current-sense resistor. the MAX16824 features three pwm inputs that control the duty cycle of the output current, allowing a wide led dimming range to be implemented. the pwm inputs also function as on/off control for each corresponding output. the max16825 offers a 2mbps, 4-wire serial interface, a 3-bit shift register, and a 3-bit transparent latch. the serial interface allows a microcontroller to configure the output channels using four inputs (din, clk, le, oe ) and a data output (dout). dout allows multiple drivers to be cascaded and operated together. the MAX16824/max16825? on-board pass elements minimize the need for external components, while at the same time, providing ?% led current accuracy. additional features include a +5v (?%) regulated output with 4ma output current capability and thermal protection. the MAX16824/max16825 are available in a thermally enhanced 16-pin tssop-ep package and specified over the -40? to +85? temperature range. applications industrial lighting architectural and decorative lighting mood lighting indoor and outdoor led video displays automotive lighting lcd display backlighting features ? 6.5v to 28v operating range ? outputs connected to 36v supply for long led strings ? three 36v-rated output channels with independently adjustable led current ? 150ma output current per channel ? ?% led current accuracy ? pwm dimming three independent dimming control inputs (MAX16824) 4-wire serial interface led current chopping (max16825) ? +5v (?%) regulated output with 4ma source capability ? fast transient dimming response ? 200mv current-sense reference reduces power loss ? thermal shutdown ? -40? to +85? operating temperature range ? thermally enhanced, 16-pin tssop exposed paddle package MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers ________________________________________________________________ maxim integrated products 1 19-1107; rev 0; 11/07 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim's website at www.maxim-ic.com. out1 out3 out2 cs1 cs2 cs3 in 1 16 3 7 8 9 4 11 12 2 15 13 pwm1 pwm2 pwm3 reg gnd c reg c in v in up to 36v r cs2 r cs1 r cs3 MAX16824 typical operating circuits ordering information part temp range pin package pkg code MAX16824 eue+ -40? to +85? 16 tssop-ep* u16e-3 max16825 eue+ -40? to +85? 16 tssop-ep* u16e-3 + denotes a lead-free package. * ep = exposed paddle. pin configurations appear at end of data sheet. out1 out3 out2 cs1 cs2 cs3 in clk din le reg gnd c reg c in v in r cs2 r cs1 r cs3 oe microcontroller max16825 1 16 3 6 7 8 9 4 11 12 2 15 13 up to 36v
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers 2 _______________________________________________________________________________________ absolute maximum ratings 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 to gnd ...............................................................-0.3v to +30v out1, out2, out3 to gnd ..................................-0.3v to +40v cs1, cs2, cs3, reg to gnd...................................-0.3v to +6v pwm1, pwm2, pwm3 to gnd .................................-0.3v to +6v din, clk, le, oe , dout to gnd ............................-0.3v to +6v maximum current into any pin (except out1, out2, out3) ........................................?0ma maximum current into out1, out2, out3......................160ma continuous power dissipation (t a = +70?) 16-pin tssop-ep (derate 18.9mw/? above +70?) ....1500mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? electrical characteristics (v in = 12v, c reg = 1? to gnd, i reg = 0, r cs_ = 2 from cs_ to gnd, t j = t a = -40? to +85?, unless otherwise noted. typical values are at t j = t a = +25?.) (note 1) parameter symbol conditions min typ max units supply voltage range v in 6.5 28.0 v gnd current i gnd i out1 = i out2 = i out3 =100ma 5 10 ma 10ma < i out_ < 100ma, 0? t j 85? 5 led current-sense accuracy (note 2) 10ma < i out_ < 100ma, -40? t j 85? 7 % i out_ = 100ma (current pulsed) 0.75 1.5 dropout voltage (note 3) v do i out_ = 150ma (current pulsed) 1.2 2.25 v output current slew rate current rising, v out = 4v 100 ma/? output current leakage i leak pwm1 = pwm2 = pwm3 = 0v 1 a current sense v cs1 = v cs2 = v cs3 , 0? t j +85? 190 200 210 regulated cs_ voltage v cs_ v cs1 = v cs2 = v cs3 , -40? t j +85? 186 200 214 mv overtemperature protection thermal shutdown temperature 165 ? thermal shutdown hysteresis 23 ? +5v regulator (reg) output voltage v reg i reg = 0ma (note 4) 4.75 5 5.25 v reg output current i reg 4.75v < v reg 4ma reg short-circuit current i regsc v reg = 0v (note 5) 15 40 90 ma logic input (pwm1, pwm2, pwm3) pwm_ input bias current i pwm v pwm1 = v pwm2 = v pwm3 = 5v 1 a pwm_ input-voltage high v ih 4v pwm_ input-voltage low v il 0.6 v pwm_ turn-on delay 50% of v pwm_ to 50% of v out_ 475 ns pwm_ turn-off delay 50% of v pwm_ to 50% of v out_ 150 ns
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers _______________________________________________________________________________________ 3 electrical characteristics (continued) (v in = 12v, c reg = 1? to gnd, i reg = 0, r cs_ = 2 from cs_ to gnd, t j = t a = -40? to +85?, unless otherwise noted. typical values are at t j = t a = +25?.) (note 1) parameter symbol conditions min typ max units outputs (out1, out2, out3) turn-on time t r pwm_ rising time, t r , is measured from 20% to 80% of i out 1s turn-off time t f pwm_ falling time, t f , is measured from 80% to 20% of i out 1s spi interface (clk, le, oe , din, dout) (figures 3 and 4) din, clk, le, oe input bias current din = clk = le = oe = 0 or 5v 1 a din, clk, le, oe input-voltage high v ih 2.2 v din, clk, le, oe input-voltage low v il 0.5 v clk clock period t cp 50% of clk rising to 50% of next clk rising, figure 3 50 ns clk pulse-width high t ch 50% of clk rising to 50% of clk falling, figure 3 24 ns clk pulse-width low t cl 50% of clk falling to 50% of clk rising, figure 3 24 ns din setup time t ds 50% of din rising to 50% of clk rising, figure 3 5ns din hold time t dh 50% of clk rising to 50% of din falling, figure 3 10 ns dout propagation delay t do 50% of clk rising to 50% of dout rising/ falling, figure 3 5ns dout rise/fall time t dr /t df c dout = 10pf, 10% to 90% of dout rising/falling edge (note 6) 15 ns dout voltage high v doh i source = 4ma 4.5 v dout voltage low v dol i sink = 4ma 0.5 v le pulse-width high t lw 50% of le rising to 50% of le falling, figure 3 20 ns le setup time t ls 50% of clk rising to 50% of le rising, figure 3 15 ns le rising to out_ rising delay t lrr 50% of le rising to 50% of out_ rising, figure 4 150 ns le rising to out_ falling delay t lrf 50% of le rising to 50% of out_ falling, figure 4 475 ns
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers 4 _______________________________________________________________________________________ electrical characteristics (continued) (v in = 12v, c reg = 1? to gnd, i reg = 0, r cs_ = 2 from cs_ to gnd, t j = t a = -40? to +85?, unless otherwise noted. typical values are at t j = t a = +25?.) (note 1) parameter symbol conditions min typ max units clk rising to out_ rising delay t crr 50% of clk rising to 50% of out_ rising, figure 4 150 ns clk rising to out_ falling delay t crf 50% of clk rising to 50% of out_ falling, figure 4 475 ns oe rising to out_ rising delay t oeh 50% of oe rising to 50% of out_ rising, figure 3 150 ns oe falling to out_ falling delay t oel 50% of oe falling to 50% of out_ falling, figure 3 475 ns note 1: all devices are 100% production tested at t j = +25? and t j = +85?. limits to -40? are guaranteed by design. note 2: this specification does not include sense resistor tolerance and ground error. note 3: dropout is measured as follows: r sc_ = 1.21 from cs_ to gnd. force 100ma into out_ and measure the dropout voltage from out_ to cs_. dvdo = ( out_ - v cs_ ). note 4: out? current regulation varies with load across reg (see the typical operating characteristics ). note 5: overtemperature protection does not function if the output of the 5v reference (reg) is shorted to ground. note 6: guaranteed by design, not production tested. 0 0.2 0.1 0.5 0.4 0.3 0.6 0.7 0.9 0.8 1.0 -40 -10 5 -25 203550658095110125 dropout voltage vs. temperature MAX16824toc01 temperature ( c) dropout voltage (v) i load = 100ma 0.182 0.192 0.187 0.197 0.202 0.207 060 45 15 30 75 90 105 120 135 150 cs_ voltage vs. output current MAX16824 toc02 output current (ma) v cs_ (v) output current vs. input voltage MAX16824 toc03 v in (v) output current (ma) 26 24 20 22 6 8 10 12 14 16 18 2 4 10 30 50 70 90 110 130 150 170 190 -10 028 i load = 150ma i load = 100ma typical operating characteristics (v in = 12v, c reg = 1? to gnd, i reg = 0, r cs_ = 2 from cs_ to gnd, t a = +25?, unless otherwise noted. typical values are at t a = +25?.)
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 5 0 40 20 100 80 60 120 140 180 160 200 -40 -10 5 -25 203550658095110125 output current vs. temperature MAX16824toc04 temperature ( c) output current (ma) i out = 150ma i out = 95ma i out = 10ma supply current vs. temperature MAX16824 toc05 temperature ( c) supply current (ma) 110 95 80 65 50 35 20 5 -10 -25 2.45 2.65 2.85 3.05 3.25 3.45 2.25 -40 125 v in = 28v v in = 6.5v v pwm = v pwm = v pwm = 0 output voltage vs. temperature MAX16824 toc06 v reg (v) 4.92 4.94 4.96 4.98 5.00 5.02 5.04 5.06 5.08 5.10 4.90 i load = 0 temperature ( c) 110 95 80 65 50 35 20 5 -10 -25 -40 125 i load = 4ma i load = 1ma cs_ voltage vs. reg output current MAX16824 toc07 i reg (ma) v cs_ (v) 9 8 6 7 2 3 4 5 1 0.183 0.184 0.186 0.185 0.187 0.188 0.189 0.190 0.191 0.192 0.193 0.194 0.195 0.196 0.197 0.198 0.199 0.200 0.182 010 i load = 100ma i load = 150ma output voltage vs. input voltage MAX16824 toc08 v in (v) v reg (v) 24 20 4 8 12 16 4.965 4.970 4.975 4.980 4.985 4.990 4.995 5.000 4.960 028 i reg = 0 i reg = 1ma i reg = 4ma 2 s/div led current fall time 0v 0a 2v/div i out_ 100ma/div MAX16824 toc09 i led = 150ma v in = 12v pulsed at 200hz (50% duty cycle) v pwm_ 2 s/div led current rise time 0v 0a 2v/div i out_ 100ma/div MAX16824 toc10 i led = 150ma v in = 12v pulsed at 200hz (50% duty cycle) v pwm_ 20 s/div 330hz dimmed operation 0v 0a v pwm_ 2v/div i out_ 100ma/div MAX16824 toc11 i load = 150ma v in = 12v pwm_ pulsed at 330hz (1% duty cycle) typical operating characteristics (continued) (v in = 12v, c reg = 1? to gnd, i reg = 0, r cs_ = 2 from cs_ to gnd, t a = +25?, unless otherwise noted. typical values are at t a = +25?.)
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers 6 _______________________________________________________________________________________ pin description pin MAX16824 max16825 name function 1 1 out1 channel 1 led driver output. out1 is an open-drain, constant-current-sinking output rated to 36v. 2 2 cs1 channel 1 sense amplifier negative input. connect a current-sense resistor between cs1 and gnd to program the output current level for channel 1. 3 3 in positive input supply. bypass with a 0.1? (min) capacitor to gnd. 4 4 reg +5v-regulated output. connect a 1? capacitor from reg to gnd. 5, 6, 10, 14 5, 14 n.c. no connection. must be left unconnected. 7 pwm1 dimming input 1. pwm1 is a dimming input for channel 1. a logic-low turns off out1 and a logic-high turns on out1. 8 pwm2 dimming input 2. pwm2 is a dimming input for channel 2. a logic-low turns off out2 and a logic-high turns on out2. 9 pwm3 dimming input 3. pwm3 is a dimming input for channel 3. a logic-low turns off out3 and a logic-high turns on out3. 11 11 gnd ground 12 12 out3 channel 3 led driver output. out3 is an open-drain, constant-current-sinking output rated to 36v. 13 13 cs3 channel 3 sense amplifier negative input. connect a current-sense resistor between cs3 and gnd to program the output current level for channel 3. 15 15 cs2 channel 2 sense amplifier negative input. connect a current-sense resistor between cs2 and gnd to program the output current level for channel 2. 16 16 out2 channel 2 led driver output. out2 is an open-drain, constant-current-sinking output rated to 36v. ?din serial-data input. data is loaded into the internal 3-bit shift register on the rising edge of clk. ?le latch-enable input. data loaded transparently from the internal shift register to the output latch while le is high. data is latched into the output latch on the le? falling edge and retained while le is low. ? oe output enable input. drive oe high to place all outputs into a high-impedance mode without altering the contents of the output latches. drive oe low to force all outputs to follow the state of the output latches. ?0dout serial-data output. data is clocked out of the internal 3-bit shift register to dout on the rising edge of clk. dout is a replica of the shift register? last bit. 6 clk clock input ep exposed paddle. connect ep to a large-area ground plane for effective power dissipation. do not use as the ic ground connection.
detailed description the MAX16824/max16825 are three-channel led dri- vers that operate from a 6.5v to 28v input voltage range. these devices provide three independent open- drain, constant-current-sinking outputs rated to 36v and deliver up to 150ma of current to each hb led string. the current in each channel is programmable using an external current-sense resistor in series with each internal power mosfet? source. the MAX16824 features three separate pwm inputs that allow a wide range of independent dimming level at each of the three outputs. the pwm inputs also function as on/off control inputs for each corresponding output (figure 1). the max16825 includes a 2mbps, 4-wire serial inter- face to control the state of each output (figure 2). the 4-wire serial interface comprises a 3-bit shift regis- ter and a 3-bit transparent latch. the shift register is updated using a clock input clk and a data input din. dout is the last bit of the shift register. this feature allows multiple drivers to be cascaded and operated together. the latch is transparent from the shift register outputs to the led output when le is high while it latch- es the shift register state on the falling edge of le. the output-enable input oe allows simultaneous enabling or disabling of all three outputs. MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers _______________________________________________________________________________________ 7 bandgap and 5v regulator thermal shutdown 200mv out1 out2 out3 cs1 cs2 cs3 pwm1 reg in gnd pwm2 pwm3 pwm control and logic MAX16824 figure 1. internal block diagram (MAX16824)
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers 8 _______________________________________________________________________________________ bandgap and 5v regulator thermal shutdown shift register shift register shift register latch latch latch logic 200mv out1 out2 out3 cs1 cs2 cs3 oe le dout clk din reg in gnd max16825 figure 2. internal block diagram (max16825)
on-board pass elements minimize the need for external components while providing ?% led current accura- cy. additional features include a +5v (?%) regulated output with 4ma output current capability and thermal protection. the MAX16824/max16825 use a feedback loop to lin- early control the current at each output. the voltage across each sense resistor is regulated to 200mv by the internal feedback loop. the output current is set by selecting the value of r cs . +5v regulator (reg) the MAX16824/max16825 include a fixed +5v output regulator that delivers up to 4ma of load current for auxiliary low power applications throughout the 6.5v to 28v input voltage range. connect a 1? compensation capacitor from reg to ground. thermal protection the MAX16824/max16825 enter a thermal shutdown mode in the event of overheating. when the junction temperature exceeds t j = +165?, the internal thermal protection circuit turns off the series pass elements. the MAX16824/max16825 recover from thermal shut- down mode when the junction temperature drops by 23?. the thermal protection does not operate if the regulator (reg) is in a short-circuit condition. 4-wire serial interface (max16825) the max16825 features a 4-wire serial interface (din, clk, le, oe ) and a data output (dout) that allows the use of a microcontroller to write brightness data to the max16825. the serial-interface data word length is 3 bits (d0, d1, d2). the functions of the interface inputs are as follows: din is the serial-data input, which must be stable when it is sampled by the max16825 on the rising edge of clk. data shifts in with the msb first. this means that data bit d2 is clocked in first, followed by 2 more data bits (d1 and finishing with the lsb d0). clk is the serial-clock input, which shifts data at din into the max16825? 3-bit shift register on the rising edge. le is the latch-enable input that allows the trans- fer of data from the max16825? 3-bit shift register to its 3-bit latch when le is high (transparent latch) and latches the data on the falling edge of le (figure 4). output enable ( oe ) provides simultaneous control of the output drivers. driving oe high places outputs out1, out2, and out3 into a high-impedance mode without altering the contents of the output latches. driving oe low allows outputs out1, out2, and out3 to follow the state of the output latches. oe is independent of the operation of the serial inter- face. data can be shifted into the serial-interface shift register and latched regardless of the state of oe . dout is the serial-data output that shifts data out from the max16825? 3-bit shift register on the rising edge of clk. data at din propagates through the shift register and appears at dout three clock cycles later. applications information programming the led current the MAX16824/max16825 use sense resistors to set the output current in 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 better performance, connect the low side of the cur- rent-sense resistors to the ic? ground terminal and the high side to the cs_ terminal with short traces. the value of the sense resistor for a given desired current is calcu- lated with the following equation: where v cs_ is 200mv and i out_ is i led (see the electrical characteristics table). input voltage considerations for proper operation, the minimum input voltage must always be: where v cs_ is the voltage drop across the sense resis- tor r cs _, v ft(max) is the total forward voltage of all series connected leds and v do is the maximum dropout voltage of the regulator. the minimum operat- ing voltage of the device is 6.5v. if the device is operat- ed below 6.5v, the output current may not meet the full regulation specification (see the typical operating characteristics ). pulse-width dimming (MAX16824) the MAX16824 includes pulsed-width current dimming inputs (pwm_) to control the led brightness. an appli- cation of up to 5khz signal or less is recommended at pwm_ input for proper operation. pwm_ also functions as an active-high enable input for each output channel. a logic-low at pwm_ turns off out_ and a logic-high turns on out_. vvv v in min cs ft max do () _ ( ) + + r vv ia cs cs out _ _ _ () () () = MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers _______________________________________________________________________________________ 9
MAX16824/max16825 pulse-width dimming (max16825) the max16825 provides three methods of pulsed-width current dimming. one method of pulse dimming the output channels is to drive oe low while latching a different set of three bits data. holding oe low allows the output channels to fol- low the state of the output latches. the duty cycle depends on le? frequency. all output channels are affected at the same time. high-voltage, three-channel linear high-brightness led drivers 10 ______________________________________________________________________________________ le clk do d1 d2 do t r t f t oel t oeh t oew 20% 80% t do t ds t dh t cl t ch t cp t lw t ls din dout oe out_ 50% 50% 50% 50% 50% 50% 50% 50% 50% 50% 50% figure 3. 4-wire serial-interface timing diagram
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers ______________________________________________________________________________________ 11 50% 50% 50% 50% le out_ t lrr out_ clk t crr out_ clk t crf le out_ t lrf 50% 50% 50% 50% figure 4. le and clk to out_ timing
MAX16824/max16825 another method of pulse dimming the outputs is to hold le high and drive oe with a pwm signal. because the input bits are always latched, the serial input constantly refreshes the register. the control bits must be carefully selected to dim the outputs properly. a third method is to hold both le and oe in the enabled state. this allows the data bits to directly con- trol the output channels, and hence, pulse dim the out- put current. make sure that the clock frequency does not exceed the maximum rate at which the device can change the state of the output channels. power dissipation the power dissipation (p d ) of the MAX16824/ max16825 is determined from the following equation: where: v in = supply voltage v inl = supply voltage to the led strings i in = supply current v led_ = total forward voltage for one led string i led_ = led current v cs = 200mv drop across r cs_ duty = pwm_ duty cycle the worst-case power dissipation occurs when the drop across each internal mosfet is at its maximum with all three channels delivering the maximum allow- able output current. the maximum drop across the internal mosfets is determined by: v inl - v led_ - v cs_ when v led_ is at its minimum. higher ambient temperature increases the thermal stress even further due to the reduction in voltage drop across the leds. the MAX16824/max16825 thermal specifica- tions are given according to the jedec-51 guidelines. good mechanical/thermal design practices must be applied to help maintain the device junction temperature below the absolute maximum ratings at all times. chip information process: bicmos-dmos p v i v v v i duty v v v i duty v v v i duty d in in inl led cs led inl led cs led inl led cs led =+ ? ? +? ? +? ? ()( )( ) ()() ()() 11 1 22 2 33 3 1 2 3 high-voltage, three-channel linear high-brightness led drivers 12 ______________________________________________________________________________________
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers ______________________________________________________________________________________ 13 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 out1 out2 cs2 n.c. cs3 out3 gnd dout oe top view tssop-ep cs1 in clk reg n.c. din le max16825 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 out1 out2 cs2 n.c. cs3 out3 gnd n.c. pwm3 top view tssop-ep cs1 in reg n.c. pwm1 pwm2 MAX16824 n.c. + + pin configurations
MAX16824/max16825 high-voltage, three-channel linear high-brightness led drivers 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. 14 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2007 maxim integrated products is a registered trademark of maxim integrated products, inc. boblet 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 .) tssop 4.4mm body.eps aa aa

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