View LT3599IFEPBF_8891037.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

lt3599 1 3599ff for more information www.linear.com/lt3599 typical application features applications description 4-string 120ma led driver with 1.5% current matching the lt ? 3599 is a fixed frequency 2 a step-up dc /dc converter designed to drive four strings of 120 ma leds up to a 44 v output voltage . the switching frequency is programmable from 200 khz to 2.1 mhz through an ex - ternal resistor.led dimming can be achieved with analog dimming on the ctrl pin , and with pulse width modulation dimming on the pwm pin . the lt3599 accurately regulates led current even when the input voltage is higher than the led output voltage. additional features include programmable led current derating, switching frequency synchronization to an ex - ternal clock , led string disable control , openled alert pin , shor tled alert pins and programmable maximum output voltage when all led strings are disconnected . the lt3599 is available in the thermally enhanced 32-pin (5mm 5mm) qfn and 28-pin tssop packages. l , lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation. true color pwm is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. protected by u.s. patents, including 7199560. 90% efficient 12w led driver n true color pwm tm dimming ratio up to 3000:1 n drives four strings of leds at up to 120ma n 1.5% accurate led current matching n wide input voltage range: 3.1v to 30v n output voltage up to 44v n regulates led current even when v in > v out n disconnects leds in shutdown n programmable maximum v out (regulated) n open/short led protection and fault flags n programmable led current derating n adjustable frequency: 200khz to 2.1mhz n synchronizable to an external clock n analog dimming up to 20:1 n programmable input uvlo with hysteresis n thermally enhanced 32-pin (5mm 5mm) qfn and 28-pin tssop packages n automotive navigation tft lcd displays n desktop and notebook tft lcd displays led current matching 10k 3.3f 47nf 10h 4.7f 2 100pf 2.2nf 3599 ta01a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 80ma per string ctrlv ref t set led1led2 led3 led4 v out sw v in v c ss gnd i set 1m 31.6k pv in 8v to 24v v in v in 16.5k 53.6k 100k disable4 100k 31.6k 33.2k 53.6k80.6k 200k 1f v in 3.1v to 5.5v temperature (c) C50 C1.5 matching (%) C1.0 0 0.5 1.0 1.5 0 50 75 C0.5 C25 25 100 150 125 3599 ta01b all four led strings downloaded from: http:///
lt3599 2 3599ff for more information www.linear.com/lt3599 pin configuration absolute maximum ratings v in , shdn / uvlo , openled , shortled .................. 30 v shdn / uvlo pin above v in ......................................... 3v sw ............................................................................ 45 v v ou t , v o_ sw .............................................................. 45 v led 1, led 2, led 3, led 4 .......................................... 45 v pwm , sync , ctrl , fb , t set , disable 4 .................... 6v v c , ss ......................................................................... 3v v ref , rt, i set .............................................................. 2v (note 1) order information lead free finish tape and reel part marking* package description temperature range lt3599efe#pbf lt3599efe#trpbf lt3599fe 28-lead plastic tssop C40c to 125c lt3599ife#pbf lt3599ife#trpbf lt3599fe 28-lead plastic tssop C40c to 125c lt3599hfe#pbf lt3599hfe#trpbf lt3599fe 28-lead plastic tssop C40c to 150c lt3599euh#pbf lt3599euh#trpbf 3599 32-lead (5mm 5mm) plastic qfn C40c to 125c lt3599iuh#pbf lt3599iuh#trpbf 3599 32-lead (5mm 5mm) plastic qfn C40c to 125c consult ltc marketing for parts specified with wider operating temperature ranges . * the temperature grade is identified by a label on the shipping container . consult ltc marketing for information on non-standard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ . some packages are available in 500 unit reels through designated sales channels with #trmpbf suffix. operating junction temperature range ( note 2) lt 3599 e/ lt 3599 i .............................. C40 c to 125 c lt 3599 h ............................................ C40 c to 150 c maximum junction temperature lt 3599 e/ lt 3599 i ............................................. 125 c lt 3599 h ........................................................... 150 c storage temperature range .................. C65 c to 150 c lead temperature ( soldering , sec ) ( note 5) ......... 300 c 12 3 4 5 6 7 8 9 1011 12 13 14 top view fe package 28-lead plastic tssop 2827 26 25 24 23 22 21 20 19 18 17 16 15 sw v out v o_sw led1led2 led3 led4 disable4 shortled nc openled nc i set ctrl v in shdn /uvlo ncgnd v ref ss rt pwm nc sync nc t set fbv c 29 t jmax = 150c, ja = 28c/w , jc = 10c/w exposed pad (pin 29) is gnd, must be soldered to pcb 32 33 31 30 29 28 27 26 25 9 10 11 12 top view uh package 32-lead (5mm 5mm) plastic qfn 13 14 15 16 17 18 19 20 21 22 23 24 8 7 6 5 4 3 2 1 v out v o_sw led1led2 led3 led4 disable4 shortled ncnc gnd v ref ss rt pwm sync ncnc nc sw vin shdn /uvlo ncnc ncnc openled i set ctrl v c fb t set t jmax = 125c, ja = 34c/w exposed pad (pin 33) is gnd, must be soldered to pcb downloaded from: http:///
lt3599 3 3599ff for more information www.linear.com/lt3599 electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. v in = 5v, v shdn = 5v, unless otherwise noted. (note 2) parameter conditions min typ max units minimum operating voltage l 2.7 3.1 v maximum operating voltage l 30 v reference voltage v ref i(v ref ) = 0a l 1.21 1.20 1.227 1.24 1.25 v v reference voltage line regulation i(v ref ) = 0a, 3.1v < v in < 30v 0.01 0.03 %/v maximum v ref pin current (note 3) 100 a v ref load regulation 0 < i(v ref ) 100a (max) 1 mv feedback voltage l 1.196 1.223 1.250 v fb pin bias current (note 3) 100 250 na fb error amp transconductance ? i = 5a 200 mhos fb error amp voltage gain 210 v/v current loop amp transconductance 50 mhos current loop amp voltage gain 50 v/v v c source current (out of pin) led1-4 = 0.4v, fb = 1v, v c = 1.5v 8 a v c sink current (ovp mode) led1-4 = 0.4v, fb = 1.5v, v c = 1.5v 15 a quiescent current v shdn = 5v, pwm = 0v, not switching, v c = 0.7v 3 4.8 ma quiescent current in shutdown v shdn = 0v 0 1 a led current r iset = 13.3k 96 99 102 ma led string current matching 100ma led current l 0.25 1.5 % led open detection threshold (v led C gnd) fb > 1.25v 0.3 0.4 v led short detection threshold (v out C v led ) 0.8 1.5 2.2 v led regulation voltage 0.77 v led1-4 leakage current v led1-4 = 45v 0.1 1 a ctrl pin bias current v ctrl = 0.8v (note 3) 100 200 na switching frequency r t = 324k r t = 53.6k r t = 20k 176 0.9 1.82 198 1 2.06 220 1.1 2.3 khz mhz mhz t set voltage 595 mv maximum switch duty cycle r t = 324k r t = 53.6k r t = 20k l l l 97.7 88.5 77 98.6 93 86 % % % switch current limit (note 4) 2 2.5 3 a switch v cesat i sw = 0.5a 0.10 v switch leakage current v sw = 45v, fb = 1.3v 0.2 5 a shdn /uvlo pin threshold (v sd_ shdn ) shutdown 0.3 0.7 0.95 v shdn /uvlo pin threshold (v sd_ uvlo ) rising 1.28 1.36 1.44 v shdn /uvlo pin hysteresis current shdn = v sd_uvlo C 50mv shdn = v sd_uvlo + 50mv 2.5 4 0 5.5 a a soft-start current ss = 1v (note 3) 11 a pwm input high threshold 1 v pwm input low threshold 0.4 v downloaded from: http:///
lt3599 4 3599ff for more information www.linear.com/lt3599 note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the lt3599e is guaranteed to meet performance specifications from 0c to 125c junction temperature. specifications over the C40c to 125c operating junction temperature range are assured by design, characterization and correlation with statistical process controls. the lt3599i is guaranteed over the full C40c to 125c operating junction temperature range. the lt3599hfe is guaranteed over the full C40c to 150c operating temperature range. high junction temperatures degrade operating lifetimes. operating lifetime is derated at junction temperatures greater than 125c. note 3: current flows out of pin. note 4: current limit guaranteed by design and/or correlation to static test. current limit is independent of duty cycle and is guaranteed by design.note 5: tssop package only. electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. v in = 5v, v shdn = 5v, unless otherwise noted. (note 2) parameter conditions min typ max units pwm pin bias current pwm = 3.3v 0.1 2 a sync input high threshold 2 v sync input low threshold 0.8 v sync pin bias current sync = 0v sync = 3.3v 0.1 0.1 1 1 a a v o_sw switch resistance 1000 openled pull-down current pwm = 5v; ledx < 0.2v, openled = 0.3v 1 ma shortled pull-down current pwm = 5v, shortled = 0.3v 1 ma disable4 input high threshold 1.15 v disable4 input low threshold 0.4 v downloaded from: http:///
lt3599 5 3599ff for more information www.linear.com/lt3599 typical performance characteristics shdn /uvlo pin turn-on threshold (v sd_uvlo ) shdn /uvlo pin (hysteresis) current v in current (shutdown) v ref switching frequency switching frequency vs r t led current vs ctrl pin soft-start pin current junction temperature (c) C50 shdn / uvlo (v) 1.40 1.35 0 50 C25 25 75 100 150 125 1.25 1.30 1.45 3599 g01 0 v in current (na) 50 150 200 250 500350 100 400 450300 3599 g03 v in = 30v v in = 3v junction temperature (c) C50 0 50 C25 25 75 100 150 125 junction temperature (c) C50 v ref (mv) 1240 1230 0 50 C25 25 75 100 150 125 1210 1220 1250 3599 g04 v in = 30v v in = 3v ctrl pin voltage (v) 0 led current (ma) 60 80 120 1.0 40 20 0 0.2 0.4 0.6 0.8 1.2 100 3599 g07 i set = 13.3k junction temperature (c) C50 i ss (a) (out of pin) 0 50 C25 25 75 100 150 125 3599 g08 10 11 13 9 8 7 12 r t (k) switching frequency (khz) 3599 g06 10000 1000 100 10 100 1000 junction temperature (c) C50 shdn / uvlo pin current (a) 0 50 C25 25 75 100 150 125 3599 g02 4 5 3 2 10 6 just before part turn-on after part turn-off junction temperature (c) C50 switching frequency (mhz) 2.0 2.5 3.0 25 75 3599 g05 1.5 1.0 C25 0 50 100 150 125 0.5 0 2.1mhz 0.2mhz 1mhz t a = 25c unless otherwise specified t set pin threshold vs junction temperature junction temperature (c) 0 500 v tset threshold (mv) 600 700 800 50 100 125 25 75 150 900 550 650 750 850 3599 g09 downloaded from: http:///
lt3599 6 3599ff for more information www.linear.com/lt3599 v c pin active and clamp voltages led current vs pwm duty cycle switch saturation voltage switch current limit feedback pin voltage led current vs temperature led current waveforms (0.1% pwm ) (10ms period) led current waveforms (90% pwm ) (10ms period) v c (v) 1500 2000 2500 1000 500 0 3599 g10 v c high v c active junction temperature (c) C50 0 50 C25 25 75 100 150 125 pwm duty cycle (%) 0.01 led current (ma) 1 100 1 10 0.1 100 3599 g11 0.1 0.01 10 junction temperature (c) C50 led current (ma) 100 99 0 50 C25 25 75 100 150 125 97 98 101 3599 g15 i sw (a) 0 0 v cesat (v) 0.10 0.20 0.30 0.5 1 2 1.5 0.40 0.05 0.15 0.25 0.35 2.5 3599 g12 2s/div pwm 5v/div sw 20v/div i led1 50ma/div 3599 g16 100s/div pwm 5v/div sw 20v/div i led1 50ma/div 3599 g17 switch current (a) 1.6 2.0 2.8 1.2 0.8 0.4 2.4 3599 g13 junction temperature (c) C50 0 50 C25 25 75 100 150 125 junction temperature (c) C50 1200 feedback pin voltage (mv) 1205 1215 1220 1225 12501235 0 50 75 1210 1240 12451230 C25 25 100 150 125 3599 g14 typical performance characteristics t a = 25c unless otherwise specified downloaded from: http:///
lt3599 7 3599ff for more information www.linear.com/lt3599 pin functions ctrl: led current control . if the ctrl pin is not used , tie this pin to v ref . disable4: allows disabling of led 4. connect disable 4 to v ref to disable led 4. if led 4 is disabled , the led 4 pin should be connected to the led 3 pin . connect disable 4 to ground to allow operation of led4.exposed pad : ground . the ground for the ic should be soldered to a continuous copper ground plane under the lt3599 die. fb: feedback pin for overvoltage protection . reference voltage is 1.223v. connect the resistive divider tap here . minimize trace area at fb . set v out according to v out = 1.223(1 + r2/r1) when overvoltage protection occurs. gnd: analog ground . tie directly to local ground plane . connect rt , i set and t set resistors between this local ground plane and their respective pins.i set : programs led current for each string . a resistor to ground programs led currents between 30 ma and 120ma . led1-4: led string output . connect the bottom cathode of each led string to these pins.openled : open led flag . an open-collector output when any led string opens.nc: no connect pins . can be left open or connected to any ground plane. pwm : input pin for pwm dimming control . above 1v allows converter switching , and below 0.4 v disables switching with v c pin level maintained . a pwm signal driving the pwm pin provides accurate dimming control . the pwm signal can be driven from 0 v to 5v. if unused , the pin should be connected to v ref . rt : a resistor to ground which programs switching fre - quency between 200 khz and 2.1mhz. for sync function , choose the resistor to program a frequency 20% slower than the sync pulse frequency . do not leave this pin open . shdn /uvlo: the shdn / uvlo pin has an accurate 1.36v threshold and can be used to program an undervoltage lockout (uvlo) threshold for system input supply using a resistor divider from supply to ground . a 4 a pin current hysteresis allows programming of undervoltage lockout (uvlo) hysteresis . 1.36 v turns the part on and removes a 4 a sink current from the pin . shdn /uvlo = 0 v reduces v in current < 0.1 a. shdn / uvlo can be directly connected to v in . do not leave this pin open. shortled : indicates a high side short ( led pin shorted to v out ). this is an open-collector output. ss: soft-start pin . place a soft-start capacitor here . upon start-up , a 11 a current charges the capacitor . use a larger capacitor for a slower start-up.sw: switch pin . this is the collector of the internal npn power switch . minimize the metal trace area connected to this pin to minimize emi.sync : frequency synchronization pin . this input allows for synchronizing the operating frequency to an external clock . the r t resistor should be chosen to program a switching frequency 20% slower than sync pulse frequency . this pin should be grounded if this feature is not used.t set : programs lt3599 junction temperature breakpoint , beyond which led currents will begin to decrease . an internal v ptat threshold ( see block diagram ) increases with junction temperature . when v ptat exceeds t set pin voltage, led currents are decreased . if the function is not required, connect t set pin to v ref pin . if the t set pin is not used, tie this pin to v ref . v c : error amplifier output pin . tie the external compensa - tion network to this pin.v in : input supply pin . must be locally bypassed with a capacitor to ground.v o_sw : drain of an internal pmos . the internal pmos disconnects the feedback resistors from the v out pin during shutdown and when the pwm pin is low. v out : output pin. this pin provides power to all leds. v ref : bandgap voltage reference . internally set to 1.227 v. this pin can supply up to 100a. can be used to program the ctrl pin voltage using resistor dividers to ground. downloaded from: http:///
lt3599 8 3599ff for more information www.linear.com/lt3599 block diagram figure 1. block diagram 3599 f01 v ptat t set ctrl v ref pwm ? + ? C + openled , shortled detection openled led1led2 led3 led4 led drive circuitry r disable4 v o_sw v out fb r2r1 i set gnd ss sw sync rt v in shdn /uvlo ? + led g m 0.7v v ref ovp g m a3 a1 1v ? + v c ? + pwm dimming logic oscillator 1.227 v ref 1.4v soft-start logic slope s q shortled a2 + ? led4 disable q1 pmos ? + downloaded from: http:///
lt3599 9 3599ff for more information www.linear.com/lt3599 operation the lt3599 uses a constant-frequency , peak current mode control scheme to provide excellent line and load regulation. operation can be best understood by referring to the block diagram in figure 1. to turn on the lt3599, the v in pin must exceed 3.1 v and the shdn / uvlo pin must exceed 1.4v. the shdn /uvlo pin threshold allows programming of an undervoltage lockout (uvlo) threshold for the system input supply us - ing a simple resistor divider . a 4 a current flows into the shdn / uvlo pin before the part turns on and is removed after the part turns on . this current hysteresis allows the programming of hysteresis for the uvlo threshold . see shutdown pin and programming undervoltage lockout in the applications information section . for part switching , the pwm pin must exceed 1v (typical). for micropower shutdown, the shdn / uvlo pin at 0 v reduces v in supply current to approximately ~0a.lt3599 has a built-in boost converter which converts the input voltage to a higher output voltage for driving leds . the led strings are connected to current sources where the current level is set with an external resistor on the i set pin . the led 1 to led 4 voltages are monitored for output voltage regulation . during normal operation , when all leds are used , the lowest led pin voltage (led1 to led4) is used to regulate the output voltage to ensure all led strings have enough voltage to run the programmed current. if the user prefers only three strings , then led string 4 can be disabled through the disable 4 pin and by connecting led4 to any other led pin . if the user prefers only two strings , then two pins are connected in parallel (i.e ., led 1,2 and led3,4 can be connected together in operation).the basic loop uses a pulse from an internal oscillator to set the sr latch and turn on the internal power npn switch q 1. the signal at the noninverting input of the pwm comparator (a2) is proportional to the sum of the switch current and oscillator ramp . when this signal exceeds the v c voltage , the pwm comparator resets the latch . the switch is then turned off , causing the inductor current to lift the sw pin and turn on an external schottky diode connected to the output . inductor current flows via the schottky diode charging the output capacitor . the switch is turned on again at the next reset cycle of the internal oscillator . during normal operation , the v c voltage controls the peak switch current limit and , hence , the inductor current available to the output leds. dimming of the leds is accomplished by either pwm dim - ming or analog dimming . pwm dimming is achieved by pulsing the led current using the pwm pin . for constant color led dimming , the lt3599 provides up to a 3000:1 wide pwm dimming range by allowing the duty cycle of the pwm pin to be reduced from 100% to as low as 0.033%. when the pwm pin is low , switching is disabled and the error amplifier is turned off so that it does not drive the v c pin. also , all internal loads on the v c pin are disabled so that the state of the v c pin is maintained on the external compensation capacitor . this feature reduces transient recovery time . when the pwm input again transitions high, the peak switch current returns to the correct value . in applications where the user can sacrifice openled , shortled fault flag diagnostics , the dimming ratios can be as high as 3000:1. analog dimming of led currents is accomplished by varying the level of ctrl pin voltage . this method , however , changes led color since dimming is achieved by changing led current . for ctrl pin voltage less than 1v, led current is defined as: i led = v ctrl ? 1330 r iset ?? ? ?? ? amps ( ) the lt3599 uses the fb pin to provide overvoltage protec - tion when all led strings are open . there is an internal pmos switch between v out and v o_sw that is controlled by the pwm signal . during the pwm off-period , this pmos is turned off , allowing for higher dimming range and lower current during shutdown . a resistor divider is connected between the v o_sw pin and ground , which sets the overvoltage protection voltage. if the led 1-4 pin voltage is below 0.3v, the string is treated as an open led string . as a result , an openled flag is set. if a led string is opened during regular operation , the output voltage will regulate to the optimum voltage for the remaining connected strings. if a short occurs between v out and any led pin during operation, the lt3599 immediately turns off the led pin current of the shorted string and sets a shortled flag . disabling the led pin current protects the lt3599 from high power thermal dissipation and ensures reliable operation . downloaded from: http:///
lt3599 10 3599ff for more information www.linear.com/lt3599 inductor selection table 1 lists several inductors that work well with the lt3599 , however , there are many other manufacturers and devices that can be used . consult each manufacturer for detailed information on their entire range of parts . ferrite core inductors should be used to obtain the best efficiency . choose an inductor that can handle the necessary peak current without saturating . also , ensure that the inductor has a low dcr ( copper wire resistance ) to minimize i 2 r power losses . values between 4.7 h and 22 h will suffice for most applications.inductor manufacturers specify the maximum current rating as the current where inductance falls by a given percentage of its nominal value . an inductor can pass a current greater than its rated value without damaging it . consult each manufacturer to determine how the maximum inductor current is measured and how much more current the inductor can reliably conduct. table 1. recommended inductors part l (h) max dcr () current rating (a) vendor b1015as-100m 817 fy- 4r7m 10 4.7 0.07 0.06 2.2 2.26 toko www.toko.com 744065100 74454068 74454010 10 6.8 10 0.04 0.055 0.065 3 2.2 2 wrth electronics www.we-online.com cdh115-100 cdh74np-120l cdh74np-150l 10 12 15 0.028 0.065 0.083 3 2.45 2.10 sumida www.sumida.com ihlp2020-bz ihlp2525-bd 10 10 0.184 0.116 2.3 2.5 vishay www.vishay.com shortled and openled detection are disabled during the start-up phase to avoid false flag generation . if an led string is open during normal operation , it will no longer be used to regulate the output voltage . the output voltage will regulate itself to find the led string with the lowest led pin voltage . fault detection ( shortled , openled ) is updated when the pwm pin is high and latched when the pwm pin is low. during start-up , 11 a of current charges the external soft-start capacitor . the ss pin directly limits the rate of voltage rise on the v c pin , which in turn , limits the peak switch current . soft-start also enables switching frequency foldback to provide a clean start-up for the lt3599. switch current limit protects the power switch and external components. operation applications information capacitor selectionlow esr ( equivalent series resistance ) ceramic capaci - tors should be used at the output to minimize the output ripple voltage . use only x 5 r or x 7 r dielectrics , as these materials retain their capacitance over wider voltage and temperature ranges than other dielectrics . a 4.7 f to 10f output capacitor is sufficient for most high output current designs. table 2 lists some suggested manufacturers . consult the manufacturers for detailed information on their entire selection of ceramic parts. table 2. recommended ceramic capacitor manufacturers taiyo yuden (408) 573-4150 www.t-yuden.com avx (843) 448-9411 www.avxcorp.com murata (770) 436-1300 www.murata.com kemet (408) 986-0424 www.kemet.com diode selectionschottky diodes , with their low forward voltage drop and fast switching speed , should be used for all lt3599 ap - plications. table 3 lists several schottky diodes that work well . the diode s average current rating must exceed the application s average output current . the diode s maximum reverse voltage must exceed the application s output volt - age. a 2 a diode is sufficient for most designs . for pwm dimming applications , be aware of the reverse leakage current of the diode . lower leakage current will drain the output capacitor less , allowing for higher dimming range . downloaded from: http:///
lt3599 11 3599ff for more information www.linear.com/lt3599 the companies below offer schottky diodes with high voltage and current ratings . standard silicon diodes (pn junction diodes) should not be used. table 3. suggested diodes part max current (a) max reverse voltage (v) manufacturer b250a dfls240 b240a b350a b340a 2 2 2 3 3 50 40 40 50 40 diodes , inc. www.diodes.com hsm150g hsm150j hsm350g 1 1 3 50 50 50 microsemi www.microsemi.com overvoltage protection the lt3599 uses the fb pin to provide overvoltage protec - tion. a resistor divider is connected between the v o_sw pin and ground (figure 2). there is an internal pmos switch between v out and v o_sw , which is controlled by the pwm signal . the pmos switch addition prevents the feedback resistor divider from draining the output capaci - tor during pwm off-period , allowing for a higher dimming range without falsely tripping the openled flag . it also reduces the system current in shutdown . this pmos has about 1 k resistance , so select fb resistor values taking this resistance into account. to set the maximum output voltage , select the values of r 1 and r 2 ( see figure 2) according to the following equation : v out(max) = 1.223v 1 + r2 r1 ?? ? ?? ? the output voltage should be set 10% higher than the normal led string operating voltage . under normal op - eration, led 1 to led 4 pin voltages are monitored and provide feedback information to the converter for output voltage regulation given the programmed led current . the output voltage regulation loop is activated only when all leds are open.programming maximum led current maximum led current can be programmed by placing a resistor between the i set pin and ground (r iset ). the i set pin resistor can be selected from 11k to 44.2k.the led current can be programmed according to the following equation: i led 1330 r iset amps ( ) (ctrl > 1v) see table 4 and figure 3 for resistor values and corre - sponding programmed led current.led current can also be adjusted by programming the ctrl pin voltage. table 4. r iset value selection for led current led current (ma) resistor on i set pin (k) 30ma 44.2 50ma 26.7 99ma 13.3 120ma 11 applications information figure 2. overvoltage protection voltage feedback connections figure 3. r iset value selection for led current 0 20 40 60 80 120 100 140 160 r iset (k) i led (ma) 80 6040 20 0 120 100 3599 f03 3599 f02 lt3599 v o_sw fb v out r2 r1 downloaded from: http:///
lt3599 12 3599ff for more information www.linear.com/lt3599 applications information as 0.033% at a pwm frequency of 100hz (figure 6). dim - ming by pwm duty cycle , allows for constant led color to be maintained over the entire dimming range.for lt3599 pwm dimming control during startup and normal operation, observe the following guidelines: (1) startup lt3599 v out start-up requires the shdn / uvlo and pwm pins to be asserted from off to on and the pwm on-time to be above a minimum value . the lowest pwm on-time allowed for fault detection is 4s. the lowest pwm on-time allowed for reaching v out regulation is typically 4 s but might be greater depending on external circuit parameters. once led current is in regulation , pwm on- time can be reduced as low as 3 s depending on external component selection.(2) v out collapse if during normal operation v out collapses due to a fault or because pwm on-time is too low , a re-start is required (see startup in item (1)). led current dimming two different types of dimming control can be used with the lt3599 . the led brightness can be set either by analog dimming ( ctrl pin voltage adjustment between 0 v and 1v) or pwm dimming ( pwm pin duty cycle adjustment ). for some applications , the preferred method of brightness control is to use a variable dc input voltage . the ctrl pin voltage can be adjusted to set the dimming of the led string ( see figures 4 and 5). as the voltage on the ctrl pin increases from 0 v to 1v, the led current increases from 0 to the programmed led current level . once the ctrl pin voltage increases beyond 1v, it has no effect on the led current. for true color pwm dimming , the lt3599 provides up to a 3000:1 pwm dimming range by allowing the duty cycle of the pwm pin to be reduced from 100% to as low figure 4. led current vs ctrl voltage figure 5. led current vs ctrl figure 6. led current using pwm dimming 3599 f05 lt3599 v ref ctrl r2 r1 ctrl pin voltage (v) 0 led current (ma) 60 80 120 1.0 40 20 0 0.2 0.4 0.6 0.8 1.2 100 3599 f04 i set = 13.3k pwm inductor current 3599 f06 led current max i led t pwm ton pwm (= 1/f pwm ) downloaded from: http:///
lt3599 13 3599ff for more information www.linear.com/lt3599 programming led current derating vs t emperature programming led current derating using the ctrl pina useful feature of the lt3599 is its ability to program a derating curve for maximum led current versus tem - perature. led data sheets provide curves of maximum- allowable led current versus temperature to warn against exceeding this current limit and damaging the led . the lt3599 allows the output leds to be programmed for maximum allowable current while still protecting the leds from excessive currents at high temperature . this is achieved by programming a voltage at the ctrl pin with a negative temperature coefficient using a resistor divider with temperature dependent resistance (figure 7). as the temperature increases , the ctrl voltage will fall below the internal 1 v voltage reference , causing led currents to be controlled by the ctrl pin voltage . the led current curve breakpoint and slope versus temperature is defined by the choice of resistor ratios and use of temperature-dependent resistance in the divider for the ctrl pin. a variety of resistor networks and ntc resistors with differ - ent temperature coefficients can be used for programming ctrl to achieve the desired ctrl curve vs temperature . table 5 shows a list of manufacturers / distributors of ntc resistors. there are several other manufacturers avail - able and the chosen supplier should be contacted for more detailed information . if an ntc resistor is used to indicate led temperature , it is effective only if the resistor is connected as closely as possible to the led strings . led derating curves shown by manufacturers are listed for ambient temperature . the ntc resistor should have the same ambient temperature as the leds . since the temperature dependency of an ntc resistor can be non - applications information linear over a wide range of temperatures , it is important to obtain a resistor s exact values over temperature from the manufacturer . hand calculations of ctrl voltage can then be performed at each given temperature , resulting in the ctrl versus temperature plotted curve . several iterations of resistor value calculations may be required to achieve the desired breakpoint and slope of the led current derating curve. table 5. ntc resistor manufacturers/distributors murata electronics north america (770) 436-1300 www.murata.com tdk corporation (516) 535-2600 www.tdk.com digi-key (800) 344-4539 www.digikey.com if calculating the ctrl voltage at various temperatures gives a downward slope that is too strong , alternative resistor networks can be chosen (b, c , d in figure 7) which use temperature-independent resistance to reduce the effects of the ntc resistor overtemperature. murata electronics provides a selection of ntc resistors with complete data over a wide range of temperatures . in addition , a software tool is available which allows the user to select from different resistor networks and ntc resistor values , and then simulate the exact output voltage curve ( ctrl behavior ) over temperature . referred to as the murata chip ntc thermistor output voltage simula - tor, users can log onto www .murata.com/ designlib and download the software followed by instructions for creat - ing an output voltage v out (ctrl) from a specified v cc supply (v ref ). at any time during the selection of circuit parameters, the user can access data on the chosen ntc resistor by clicking on a link to the murata catalog. figure 7 . led current derating vs temperature using ntc resistor 3599 f07 r y r y r x r x r ntc r ntc r ntc r ntc d c b a lt3599 v ref ctrl r2 r1(option a to d) downloaded from: http:///
lt3599 14 3599ff for more information www.linear.com/lt3599 applications information using the t set pin for thermal protection the lt3599 contains a special programmable thermal regulation loop that limits the internal junction temperature of the part . since the lt3599 topology consists of a single boost converter with four linear current sources , any led string voltage mismatch will cause additional power to be dissipated in the package . this topology provides excellent current matching between led strings and allows a single power stage to drive a large number of leds , but at the price of additional power dissipation inside the part (which means a higher junction temperature ). being able to limit the maximum junction temperature allows the benefits of this topology to be fully realized . this thermal regulation feature provides important protection at high ambient tem - peratures, and allows a given application to be optimized for typical , not worst case , ambient temperatures with the assurance that the lt3599 will automatically protect itself and the led strings under worst-case conditions. the operation of the thermal loop is simple . as the ambi - ent temperature increases , so does the internal junction temperature of the part . once the programmed maximum junction temperature is reached , the lt3599 begins to linearly reduce the led current , as needed , to try and maintain this temperature . this can only be achieved when the ambient temperature stays below the desired maximum junction temperature . if the ambient tempera - ture continues to rise past the programmed maximum junction temperature , the leds current will be reduced to approximately 5% of the full led current.while this feature is intended to directly protect the lt3599 , it can also be used to derate the led current at high tem - peratures. since there is a direct relationship between the led temperature and lt3599 junction temperature , the t set function also provides some led current derating at high temperatures. two external resistors program the maximum ic junction temperature using a resistor divider from the v ref pin , as shown in figure 8. choose the ratio of r 1 and r 2 for the desired junction temperature . table 6 shows commonly used values for r1 and r2 (see t set graph). table 6. resistor values to program maximum ic junction temperature t j (c) r1 (k) r2 (k) 100 80.6 53.6 105 82.5 53.6 110 82.5 51.1 115 84.5 51.1 120 84.5 49.9 135 84.5 44.2 145 90.9 44.2 programming switching frequencythe switching frequency of the lt3599 is set between 200 khz and 2.1 mhz by an external resistor connected between the rt pin and ground ( see table 7). do not leave this pin open. selecting the optimum switching frequency depends on several factors . inductor size is reduced with higher frequency, but efficiency drops due to higher switching losses . in addition , some applications require very high duty cycles to drive a large number of leds from a low supply . low switching frequency allows a greater operational duty cycle and , hence , a greater number of leds to be driven . in each case , the switching frequency can be tailored to provide the optimum solution . when programming the switching frequency , the total power losses within the ic should be considered. table 7. switching frequency switching frequency (mhz) r t (k) 2.1 20 2.0 21.5 1.5 31.6 1.0 53.6 0.5 121 0.4 154 0.3 210 0.2 324 figure 8. programming the t set pin 3599 f08 lt3599 v ref t set r2 r1 downloaded from: http:///
lt3599 15 3599ff for more information www.linear.com/lt3599 switching frequency synchronizationthe nominal operating frequency of the lt3599 is pro - gram med using a resistor from the rt pin to ground and can be controlled over a 200 khz to 2.1 mhz range . in ad - dition, the internal oscillator can be synchronized to an external clock applied to the sync pin . the synchronizing clock signal input to the lt3599 must have a frequency between 240 khz and 2mhz, a pulse on-time of at least 50ns, a pulse off-time of at least 300ns, a low state below 0.8 v and a high state above 2v. synchronization signals outside of these parameters will cause erratic switching behavior. for proper operation , an r t resistor should be chosen to program a switching frequency 20% slower than the sync pulse frequency . synchronization occurs at a fixed delay after the rising edge of sync.the sync pin should be grounded if the clock synchroniza - tion feature is not used . when the sync pin is grounded , the internal oscillator generates switching frequency to the converter. shutdown and programming undervoltage lockout the lt3599 has an accurate 1.4 v shutdown threshold at the shdn / uvlo pin . this threshold can be used in conjunction with a resistor divider from the system input supply to define an accurate undervoltage lockout (uvlo) threshold for the system (figure 10). a pin current hys - teresis allows programming of the hysteresis voltage for this uvlo threshold . just before the part turns on , 4a applications information flows into the shdn / uvlo pin . after the part turns on , 0 a flows from the shdn / uvlo pin . calculation of the on / off thresholds for a system input supply using the lt3599 shdn /uvlo pin can be made as follows : v s(off) = 1.4 1 + r1 r2 ?? ? ?? ? v s(on) = v s(off) + (4a ? r1) a simple open drain transistor can be added to the resistor divider network at the shdn / uvlo pin to independently control the turn off of the lt3599.with the shdn / uvlo pin connected directly to the v in pin , an internal undervoltage lockout threshold of approximately 2.7 v exists for the v in pin . this prevents the converter from operating in an erratic mode when supply voltage is too low . the lt3599 provides a soft-start function when recovering from such faults as shdn < 1.4 v and / or v in < 2.7v. see soft-start in the applications information section for details.soft-start and switching frequency foldback to limit inrush current and output voltage overshoot dur - ing start-up / recovery from a fault condition , the lt3599 provides a soft-start pin , ss . the ss pin is used to pro - gram switch current ramp-up timing using a capacitor to ground . the lt3599 monitors system parameters for the following faults: v in < 2.7v or shdn < 1.4. on detection of any of these faults , the lt3599 stops switching im - figure 10. programming undervoltage lockout (uvlo) with hysteresis figure 9. switching frequency 3599 f11 v s r1 11 lt3599 r2 1.4v 4a shdn /uvlo ? + on off rt (k) switching frequency (khz) 3599 f10 10000 1000 100 10 100 1000 downloaded from: http:///
lt3599 16 3599ff for more information www.linear.com/lt3599 applications information mediately and a soft-start latch is set causing the ss pin to be discharged ( see the soft-start pin timing diagram in figure 11). all faults are detected internally and do not require external components . when all faults no longer exist and the ss pin has been discharged to at least 0.25v, the soft-start latch is reset and an internal 11 a supply charges the ss pin . during start-up or recovery from a fault, the ss pin ramp up controls the ramp up of switch current limit. soft-start ramp rate is given by: ? v ss ? t = i ss c ss i ss = 11a typ ( ) a 10 nf capacitor from the ss pin to ground will therefore provide a 1v/ms ramp rate on the ss pin. in addition , during soft-start , switching frequency is re - duced to protect the inductor from high currents.a useful feature of the lt3599 is that it waits for the first pwm pin active high (minimum 200 ns pulse width ) before it allows the soft-start of v c pin to begin . this feature ensures that during start-up of the lt3599 the soft-start ramp has not timed out before pwm is asserted high . without this wait for pwm high feature , systems which apply pwm after v in and shdn are valid , can potentially turn on without soft-start and experience high inductor currents during wake up of the converter s output voltage . it is important to note that when pwm subsequently goes low, the soft-start ramp is not held at its present voltage but continues to ramp upwards . if the soft-start ramp voltage was held every time pwm goes low , this would figure 11. soft-start pin timing diagram cause very slow start-up of led displays for applications using very high pwm dimming ratios. openled flag the openled pin is an open-collector output and needs an external resistor tied to a supply ( see figure 12). if any led string is open during normal operation , the openled pin will be pulled down. the open led detection is enabled only when the pwm signal is enabled . there is a delay for openled flag genera - tion when the pwm signal is enabled to avoid generating a spurious flag signal. during start-up ( see the operation section ), the open led detection is disabled. shortled flag the shortled pin is an open-collector output , and needs an external resistor tied to a supply ( see figure 12). if any led pin is shorted to v out during normal operation , the shortled pin will be pulled down . in addition , the shorted led string is immediately disabled , thereby protecting the lt3599. during the short circuit fault , cable inductance can cause the led pin voltage to overshoot past v out voltage. to avoid led pin voltage exceeding it s absolute maximum rated voltage , the anode of a 1n4148 ws diode should be connected to the led pin and the cathode of the diode connected to the v out pin . keep the traces as short as possible . a schottky diode should not be used due to high reverse bias leakage currents. the short led detection is enabled only when the pwm signal is enabled . there is a delay for shortled flag generation when the pwm signal is enabled to avoid spurious signal being generated. during start-up , the shortled flag is disabled ( see the operation section). sw ss 3599 f12 v in < 2.7v or shdn < 1.4v ss < 0.25v and v in > 2.7v and shdn > 1.4v and pwm > 1v (for >200ns) faults triggering soft-start latch with sw turned off immediately: soft-start latch reset: soft-start latch set 0.3v (active threshold) 0.25v (reset threshold) 0.15v figure 12. openled and shortled connection 3599 f13 lt3599 openled r1 shortled r2 downloaded from: http:///
lt3599 17 3599ff for more information www.linear.com/lt3599 applications information loop compensation the lt3599 has an internal transconductance error amplifier for led current regulation whose v c output compensates the control loop . during overvoltage , the v c node also compensates the control loop . the external inductor, output capacitor , and the compensation resistor and capacitor determine the loop stability . the inductor and output capacitor are chosen based on performance , size and cost . the compensation resistor and capacitor at v c are selected to optimize control loop stability . for typical led applications , a 2.2 nf compensation capacitor in series with a 10k resistor at v c is adequate. thermal consideration the lt3599 provides current for four led strings with internal npn devices serving as constant-current sources . when led strings are regulated , the lowest led pin volt - age is 0.7v. the higher the programmed led current , the more power dissipation in the lt3599. for 100 ma led programming current with a 100% pwm dimming ratio , at least 280 mw is dissipated within the ic due to current sources. thermal calculations shall include the power dissipation on current sources in addition to conventional switch dc loss , switch ac loss and input quiescent loss . for best efficiency , it is recommended that all strings have the same number of leds , and each string has a similar voltage drop across the leds.board layout considerations as with all switching regulators , careful attention must be paid to the pcb board layout and component placement . to prevent electromagnetic interference (emi) problems , proper layout of high frequency switching paths is essential . minimize the length and area of all traces connected to the switching node pin ( sw). always use a ground plane under the switching regulator to minimize interplane coupling . good grounding is essential in led fault detection . rec - ommended component placement is shown in figure 13. figure 13. recommended component placement 3599 f13 1 34 5 6 7 8 9 1011 12 13 14 lt3599 led1led2 led3 led4 disable4 shortled nc openled nc i set ctrl v out led + (v out ) power v in 2 v o_sw schottky diode v in shdn /uvlo ncgnd v ref ssr t pwm nc sync nc t set fbv c c out ground exposed pad (pin 29) power ground solder exposed pad (pin 29) to the entire copper ground plane underneath the device. connect multiple ground planes through vias underneath the ic 2827 26 25 24 23 22 21 20 19 18 17 16 15 bypass capacitor inductor r r r sw c vref c vin c ss r t r r c c r c c f downloaded from: http:///
lt3599 18 3599ff for more information www.linear.com/lt3599 total led current (ma) 40 60 efficiency (%) 65 75 80 85 100 95 120 200 240 70 90 80 160 280 320 3599 ta02b pv in = 24v pv in = 12v typical applications 12w led driver 1mhz boost, 80ma per string, 10 leds per string efficiency pwm dimming range 1000:1 (10ms period) 10s/div pwm 5v/div i led total 200ma/div 3599 ta02c r c 10k c13.3f 25v c447nf c1: murata grm21br71e335kc2: murata grm31cr71h475k d1: diodes inc. dfls240 d2, d3, d4, d5: diodes inc. 1n4148ws (see shortled flag in applications information section)l1: vishay ihlp2020bzer100m01 l1 10h c24.7f 50v 2 100pf d2 d3 d4 d5 c c 2.2nf 3599 ta02a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 80ma per string ctrlv ref t set led1led2 led3 led4 v out sw d1 v in v c ss gnd i set r101m r1131.6k v in v in 3.1v to 5.5v v in r9 16.5k r653.6k r5100k disable4 r4100k r231.6k r333.2k r753.6k r8 80.6k r1200k pv in 8v to 24v c31f 6.3v downloaded from: http:///
lt3599 19 3599ff for more information www.linear.com/lt3599 typical applications 12w led driver 400khz boost, tw o led strings, 200ma per string, 8 leds per string c13.3f 25v c447nf l1 22h d1 3599 ta03a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 200ma per string ctrlv ref t set led1led2 led3 led4 v out sw v in v c ss gnd i set v in v in 3.1v to 5.5v v in r9 13.3k r6154k r5100k r4100k disable4 r264.9k r1264.9k r753.6k r880.6k r1200k r3464k r c 3.01k 100pf c c 10nf r101m r1139.2k c24.7f 50v 3 8 leds/string pv in 9v to 16v ctrl c31f 6.3v c1: murata grm21br71e335kc2: murata grm31cr71h475k d1: diodes inc. dfls240 l1: vishay ihlp2525czer220m11 downloaded from: http:///
lt3599 20 3599ff for more information www.linear.com/lt3599 typical applications 7w led driver sepic (survives output short to ground) 300khz, three strings, 100ma per string, 6 leds per string r c 10k c13.3f 25v c447nf l1 22h l222h d1 c24.7f 50v 2 c7 4.7f 25v c6 1f 25v 100pf c c 2.2nf 3599 ta04a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 100ma per string 6 leds/string ctrlv ref t set led1led2 led3 led4 v out sw v in v c ss gnd i set r101m 10 r1149.9k v in v in r9 13.3k r6210k r5100k r4100k disable4 r753.6k r880.6k r1200k r2 31.6k r3 33.2k v in 3.1v to 5.5v pv in 8v to 16v c31f 6.3v c1: murata grm21br71e335kc2: murata grm31cr71h475k d1: diodes inc. b360a l1, l2: vishay ihlp2525czer220m11 downloaded from: http:///
lt3599 21 3599ff for more information www.linear.com/lt3599 typical applications 8w led driver 2mhz boost, three strings, 100ma per string, 7 leds per string c13.3f 25v c447nf l1 4.7h d1 3599 ta05a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 100ma per string ctrlv ref t set led1led2 led3 led4 v out sw v in v c ss gnd i set v in v in r9 13.3k r621.5k r5100k r4100k disable4 r753.6k r880.6k r1200k r2 31.6k r333.2k r c 10k 100pf c c 2.2nf r101m r11 43.2k c24.7f 50v 2 7 leds/string v in 3.1v to 5.5v pv in 8v to 16v c31f 6.3v c1: murata grm21br71e335kc2: murata grm31cr71h475k d1: diodes inc. dfls240 l1: sumida cdrh4d22hpnp-4r7n downloaded from: http:///
lt3599 22 3599ff for more information www.linear.com/lt3599 typical applications 2.1 mhz boost, four strings, 80ma per string, 7 leds per string r c 10k c13.3f 25v c447nf l1 4.7h d1 c24.7f 50v 2 7 leds/string 100pf c c 2.2nf r916.5k 3599 ta06a lt3599 v o_sw fb openled shortled pwm shdn /uvlo rt sync pwm 80ma per string ctrlv ref t set led1led2 led3 led4 v out sw v in v c ss gnd i set r101m r1143.2k pv in 9v to 16v v in v in 3.1v to 5.5v v in r620k r5100k disable4 r4100k r753.6k r880.6k r1200k r2 32.4k r3 32.4k c31f 6.3v c1: murata grm21br71e335kc2: murata grm31cr71h475k d1: diodes inc. dfls240 l1: sumida cdrh4d22hpnp-4r7n pwm 5v/div i led total 200ma/div 10s/div 3599 ta07 pwm dimming 3000:1 (10ms period) downloaded from: http:///
lt3599 23 3599ff for more information www.linear.com/lt3599 package description fe package 28-lead plastic tssop (4.4mm) (reference ltc dwg # 05-08-1663 rev k) exposed pad variation eb fe28 (eb) tssop rev k 0913 0.09 ? 0.20 (.0035 ? .0079) 0 ? 8 0.25 ref 0.50 ? 0.75 (.020 ? .030) 4.30 ? 4.50* (.169 ? .177) 1 3 4 5 6 7 8 9 10 11 12 13 14 19 20 22 21 15 16 18 17 9.60 ? 9.80* (.378 ? .386) 4.75 (.187) 2.74 (.108) 28 27 26 2524 23 1.20 (.047) max 0.05 ? 0.15 (.002 ? .006) 0.65 (.0256) bsc 0.195 ? 0.30 (.0077 ? .0118) typ 2 recommended solder pad layout exposed pad heat sink on bottom of package 0.45 0.05 0.65 bsc 4.50 0.10 6.60 0.10 1.05 0.10 4.75 (.187) 2.74 (.108) millimeters (inches) *dimensions do not include mold flash. mold flash shall not exceed 0.150mm (.006") per side note:1. controlling dimension: millimeters 2. dimensions are in 3. drawing not to scale see note 4 4. recommended minimum pcb metal size for exposed pad attachment 6.40 (.252) bsc please refer to http:// www .linear.com/product/lt3599#packaging for the most recent package drawings. downloaded from: http:///
lt3599 24 3599ff for more information www.linear.com/lt3599 package description uh package 32-lead plastic qfn (5mm 5mm) (reference ltc dwg # 05-08-1693 rev d) 5.00 0.10 (4 sides) note:1. drawing proposed to be a jedec package outline m0-220 variation whhd-(x) (to be approved) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.20mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package pin 1top mark (note 6) 0.40 0.10 31 12 32 bottom viewexposed pad 3.50 ref (4-sides) 3.45 0.10 3.45 0.10 0.75 0.05 r = 0.115 typ 0.25 0.05 (uh32) qfn 0406 rev d 0.50 bsc 0.200 ref 0.00 C 0.05 0.70 0.05 3.50 ref (4 sides) 4.10 0.05 5.50 0.05 0.25 0.05 package outline 0.50 bsc recommended solder pad layout apply solder mask to areas that are not soldered pin 1 notch r = 0.30 typ or 0.35 45 chamfer r = 0.05 typ 3.45 0.05 3.45 0.05 please refer to http:// www .linear.com/product/lt3599#packaging for the most recent package drawings. downloaded from: http:///
lt3599 25 3599ff for more information www.linear.com/lt3599 information furnished by linear technology corporation is believed to be accurate and reliable . however, no responsibility is assumed for its use . linear technology corporation makes no representa - tion that the interconnection of its circuits as described herein will not infringe on existing patent rights . revision history rev date description page number d 01/10 updated typical applications added h-grade to abs max ratings and order information updated typical performance characteristics revised pin functions updated table 6 and deleted text in programming switching frequency section added to related parts table 1, 18, 19, 20, 21, 22 2 5, 6 7 1426 e 08/10 updated fe package t jmax updated maximum switch duty cycle electrical specificationsupdated sync pin electrical specifications and added h-grade information to note 2 updated pwm dimming guidelines updated sync timing description updated shortled flag description (clamp diodes) updated typical application (clamp diodes example) 23 4 1215 16 18 f 02/16 changed the data sheet title from 4-channel to 4-string clarified the disable4 pin functionclarified the operations section clarified the shortled flag section clarified the loop compensation section clarified the related parts table 17 9 1617 26 (revision history begins at rev d) downloaded from: http:///
lt3599 26 3599ff for more information www.linear.com/lt3599 ? linear technology corporation 2009 lt 0216 rev f ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/lt3599 related parts part number description comments lt3463/ lt3463a dual output, boost/inverter, 250ma i sw , constant off-time, high efficiency step-up dc/dc converter with integrated schottkys v in : 2.3v to 15v, v out(max) = 40v, i q = 40a, i sd < 1a, 3mm 3mm dfn-10 package lt3466/ lt3466-1 dual constant current, 2mhz, high efficiency white led boost regulator with integrated schottky diode v in : 2.7v to 24v, v out(max) = 40v, i q = 5a, i sd < 16a, 3mm 3mm dfn-10 package lt3474 36v, 1a (i led ), 2mhz, step-down led driver v in : 4v to 36v, v out(max) = 13.5v, true color pwm dimming = 400:1, i sd < 1a, tssop-16e package lt3475 dual 1.5a (i led ), 36v, 2mhz, step-down led driver v in : 4v to 36v, v out(max) = 13.5v, true color pwm dimming = 3000:1, i sd < 1a, tssop-20e package lt3476 quad output 1.5a, 2mhz high current led driver with 1000:1 dimming v in : 2.8v to 16v, v out(max) = 36v, true color pwm dimming = 1000:1, i sd < 3a, 5mm 7mm qfn-10 package lt3477 3a, 42v, 3mhz boost, buck-boost, buck led driver v in : 2.5v to 25v, v out(max) = 40v, dimming = analog/ pwm , i sd < 1a, qfn and tssop-20e packages lt3478/ lt3478-1 high current led driver v in : 2.8v to 36v, v out(max) = 42v, true color pwm dimming = 3000:1, i sd < 10a, tssop-16e package lt3486 dual 1.3a, 2mhz high current led driver v in : 2.5v to 24v, v out(max) = 36v, true color pwm dimming = 1000:1, i sd < 1a, 5mm 3mm dfn and tssop-16e packages lt3496 45v, 2.1mhz 3-channel (i led = 1a) full featured led driver v in : 3v to 30v (40v max ), v out(max) = 45v, true color pwm dimming = 3000:1, i sd < 1a, 4mm 5mm qfn-28 package lt3497 dual 2.3mhz, full function led driver with integrated schottkys and 250:1 true color pwm dimming v in : 2.5v to 10v, v out(max) = 32v, i q = 6ma, i sd < 12a, 2mm 3mm dfn-10 package lt3498 2.3mhz, 20ma led driver and oled driver with integrated schottkys v in : 2.5v to 12v, v out(max) = 32v, i q = 1.65ma, i sd < 9a, 2mm 3mm dfn-12 package lt3518/ lt3517 2.3a/1.3a 45v, 2.5mhz full featured led driver with t rue color pwm dimming v in : 3v to 30v (40v max ), v out(max) = 42v, true color pwm dimming = 3000:1, i sd < 5a, 4mm 4mm qfn-16 package lt3590 48v buck mode led driver v in : 4.5v to 55v, v out(max) = 5v, i q = 700a, i sd < 15a, 2mm 2mm dfn-6 and sc70 packages lt3591 constant current, 1mhz, high efficiency white led boost regulator with integrated schottky diode and 80:1 t rue color pwm dimming v in : 2.5v to 12v, v out(max) = 40v, i q = 4ma, i sd < 9a, 2mm 3mm dfn-8 package lt3595 45v, 2.5mhz 16-channel full featured led driver v in : 4.5v to 45v, v out(max) = 45v, true color pwm dimming = 5000:1, i sd < 1a, 5mm 9mm qfn-56 package lt3598 44v, 1.5a, 2.5mhz boost 6-string led driver v in : 3v to 30v, v out(max) = 44v, true color pwm dimming = 3000:1, i sd < 1a, 4mm 4mm qfn-24 package lt3754 16-string 50ma led driver v in : 6v to 40v, v out(max) = 60v, 3,000:1 true color pwm dimming, i sd < 2a, 5mm 5mm qfn-32 package lt3760 8-string 100ma led driver v in : 6v to 40v, v out(max) = 60v, 3,000:1 true color pwm dimming, i sd < 2a, tssop-28e package downloaded from: http:///

▲Up To Search▲

Price & Availability of LT3599IFEPBF

	To Download LT3599IFEPBF Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .