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lt3479 1 3479fc typical application description 3a, full featured dc/dc converter with soft-start and inrush current protection the lt ? 3479 is a current mode, ? xed frequency step-up dc/dc converter with an internal 3a, 42v switch. ef? cien- cies of up to 89% can be achieved in typical applications. it features a programmable soft-start function to limit induc- tor current during start-up and inrush current protection to protect the lt3479 during shorts and line transients. both inputs of the error ampli? er are available to the user allowing positive and negative output voltages. through an external resistor, the user can program the switch- ing frequency from 200khz to 3.5mhz. the low pro? le (0.75mm) 14-pin, 4mm 3mm dfn package provides excellent thermal performance in a small footprint. the lt3479 is also available in a thermally enhanced 16-pin tssop package. 5v to 12v boost converter features applications n high power led driver n dsl modems n distributed power n wide input voltage range: 2.5v to 24v n 3a, 42v internal switch n high ef? ciency power conversion: up to 89% n soft-start n frequency set by external resistor: 200khz to 3.5mhz n protection against input short circuits and hot plugging n low v cesat switch: 0.3v at 2.5a (typical) n capable of positive and negative outputs n available in thermally enhanced 14-lead (4mm 3mm) dfn and 16-lead tssop packages 5v to 12v ef? ciency 200k 23.2k 17.8k 10k 2.2f v in 5v 4.7h 3479 ta01 fbn sw lv s v in v c gnd r t v ref shdnss lt3479 fbp 2.2nf 10f v out 12v0.8a 10nf i out (a) 0 efficiency (%) 70 80 0.8 3479 ta02 60 0.2 0.4 0.6 90 65 75 85 l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. downloaded from: http:///
lt3479 2 3479fc absolute maximum ratings sw, l, v s voltages ................................................... 42v v in , shdn voltages ................................................. 24v fbp, fbn, v ref , r t , v c voltages ................................. 2v junction temperature .......................................... 125c (note 1) 1413 12 11 10 98 12 3 4 5 6 7 gndgnd ss v c fbnfbp v ref swsw l v s v in r t shdn top view 15 de14 package 14-lead (4mm 3mm) plastic dfn t jmax = 125c, ja = 43c/w exposed pad (pin 15) is pgnd (must be soldered to pcb) fe package 16-lead plastic tssop 12 3 4 5 6 7 8 top view 1615 14 13 12 11 10 9 swsw l v s v in r t shdn gnd gndgnd gnd ss v c fbnfbp v ref 17 t jmax = 125c, ja = 38c/w exposed pad (pin 17) is pgnd (must be soldered to pcb) pin configuration order information lead free finish tape and reel part marking package description temperature range lt3479ede#pbf lt3479ede#trpbf 3479 14-lead (4mm 3mm) plastic dfn C40c to 85c lt3479efe#pbf lt3479efe#trpbf 3479efe 16-lead plastic tssop C40c to 85c lead based finish tape and reel part marking package description temperature range lt3479ede lt3479ede#tr 3479 14-lead (4mm 3mm) plastic dfn C40c to 85c lt3479efe lt3479efe#tr 3479efe 16-lead plastic tssop C40c to 85c consult ltc marketing for parts speci? ed with wider operating temperature ranges. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/ operating temperature range (note 2).... C40c to 85c storage temperature range ................... C65c to 125c lead temperature (soldering, 10 sec) tssop .............................................................. 300c downloaded from: http:///
lt3479 3 3479fc electrical characteristics 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 lt3479 is guaranteed to meet performance speci? cations from 0c to 70c. speci? cations over the C40c to 85c operating parameter conditions min typ max units minimum input voltage l 2.3 2.5 v quiescent current v in = 2.5v, v shdn = 0v v in = 2.5v, v shdn = 2.5v, v c = 0.3v (not switching) 0.1 5 1 7.5 a ma reference voltage measured at v ref pin l 1.216 1.235 1.250 v reference voltage line regulation 2.5v < v in < 24v, v c = 0.3v 0.01 0.03 %/v maximum v ref pin current out of pin 100 a soft-start pin current ss = 0.5v, out of pin 9 a fbp pin bias current 25 100 na fbn pin bias current 25 100 na feedback ampli? er offset voltage fbp C fbn, v c = 1v C2 2 6 mv feedback ampli? er voltage gain 250 v/v feedback ampli? er transconductance 150 s feedback ampli? er sink current v fbp = 1.25v, v fbn = 1.5v, v c = 0.5v 10 a feedback ampli? er source current v fbp = 1.25v, v fbn = 1v, v c = 0.5v 10 a switching frequency r t = 17.8k r t = 113k r t = 1.78k 0.9 160 2.7 1 200 3.5 1.15 240 4.1 mhz khz mhz maximum switch duty cycle r t = 17.8k l 84 93 % shdn pin current v shdn = 5v v shdn = 0v 30 0.1 60 1 aa shdn pin threshold 0.3 1.5 2 v inductor current limit (note 3) 3.5 5 6.5 a switch current limit (note 3) 3 4.5 6 a switch v cesat i sw = 1a (note 3) 120 200 mv switch leakage current sw = 40v 0.2 5 a the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v in = 2.5v, v shdn = 2.5v. temperature range are assured by design, characterization and correlation with statistical process controls. note 3: inductor current limit, switch current limit and switch v cesat for de package guaranteed by design and/or correlation to static test. downloaded from: http:///
lt3479 4 3479fc typical performance characteristics switch current (a) 0 0 v ce(sat) (v) 0.1 0.2 0.3 125c C50c 0.50.4 0.5 1 1.5 2 3479 g01 2.5 3 25c temperature (c) C50 current (a) 4 5 6 25 75 3479 g02 3 2 C25 0 50 100 125 1 0 inductor current limit switch current limit temperature (c) C50 1.21 v ref (v) 1.22 1.23 1.24 1.261.25 1.27 C25 0 25 50 3479 g03 75 125 100 150 v in = 24v v in = 2.5v temperature (c) C50 1.250 shdn threshold (v) 1.375 1.500 1.625 1.750 C25 0 25 50 3479 g04 75 100 125 v shdn (v) 0 0 shdn pin current (a) 10 20 30 40 50 4 81 21 6 3479 g05 20 24 C50c 25c 125c temperature (c) C50 2 v in pin current (ma) 3 4 5 6 C25 0 25 50 3479 g06 75 125 100 150 v c = 0.3v temperature (c) C50 0 i ss (a) 5 10 15 20 C25 0 25 50 3479 g07 75 125 100 150 temperature (c) C50 0 frequency (mhz) 0.4 0.8 1.2 1.6 2.0 C25 0 25 50 3479 g08 75 125 100 150 r t = 10k r t = 15k r t = 20k temperature ( c) ?50 0 offset voltage (mv) 1 2 3 4 5 ?25 02 55 0 3479 g09 75 100 v c = 0.5v v c = 1v shdn pin turn-on threshold shdn pin current v in pin current soft-start pin current oscillator frequency feedback ampli? er offset voltage switch v ce(sat) inductor and switch current limit v ref downloaded from: http:///
lt3479 5 3479fc pin functions sw (pins 1, 2/pins 1, 2): switch pins. collector of the internal npn power switch. connect the inductor and diode here and minimize the metal trace area connected to this pin to minimize electromagnetic interference. l (pin 3/pin 3): inductor pin. connect the inductor to this pin.v s (pin 4/pin 4): inductor supply. must be locally bypassed. powers the switch and the inductor. in case only one supply voltage is available, tie v in and v s together. v in (pin 5/pin 5): input supply. must be locally bypassed. powers the internal control circuitry. r t (pin 6/pin 6): timing resistor pin. adjusts the switch- ing frequency. do not leave this pin open. see table 4 for r t values and switching frequencies. shdn (pin 7/pin 7): shutdown. tie to 1.5v or greater to enable the device. tie below 0.3v to turn off the device. v ref (pin 8/pin 9): bandgap voltage reference. internally set to 1.235v. connect this pin to fbp if generating a posi- tive output, or to an external resistor divider if generating a negative voltage. this pin can provide up to 100a of current and can be locally bypassed with a 100pf capacitor. fbp (pin 9/pin 10): the noninverting input to the error ampli? er. connect resistive divider tap here for negative output voltage. fbn (pin 10/pin 11): the inverting input to the error ampli? er. connect resistive divider tap here for positive output voltage. v c (pin 11/pin 12): compensation pin for error ampli? er. connect a series rc from this pin to gnd. typical values are 10k and 2.2nf. ss (pin 12/pin 13): soft-start. place a soft-start capacitor here. leave ? oating if not in use. gnd (pins 13, 14/pins 8, 14, 15, 16): ground. tie directly to local ground plane.exposed pad (pin 15/pin 17): power ground. must be connected to electrical pcb ground. (dfn/tssop) downloaded from: http:///
lt3479 6 3479fc block diagram C + C + C + C + + C c ss c in c c c s c1 r1 fb l sw d1 l1 r c r2 8.5mw fbpfbn shdn v ref v in r t r t v c v s icon slope ss feedback amplifier pwm comparator current limit comparator inrush current protection comparator master latch driver gnd q1 3479 bd pwmout 36mv oscillator rq s t t 1.25v reference downloaded from: http:///
lt3479 7 3479fc operation the lt3479 uses a ? xed frequency, current mode control scheme to provide excellent line and load regulation. op- eration can be best understood by referring to the block diagram. the start of each oscillator cycle sets the sr latch and turns on power switch q1. the signal at the inverting input of the pwm comparator (slope) is proportional to the sum of the switch current and oscillator ramp. when slope exceeds v c (the output of the feedback ampli? er), the pwm comparator resets the latch and turns off the power switch. in this manner, the feedback ampli? er and pwm comparators set the correct peak current level to keep the output in regulation. the lt3479 also features a soft-start function. during start-up, 10a 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 cur- rent. the switch current is constantly monitored and not allowed to exceed the nominal value of 3a. if the switch current reaches 3a, the sr latch is reset regardless of the output of the pwm comparator. current limit protects the power switch and external components. soft-start plays an important role in applications where the switch will reach levels of 30v or higher. during startup, an overshoot in the switch current together with the pres- ence of high switch voltage can overstress the switch. a properly used soft-start feature will greatly improve the robustness of such designs. in addition to soft-start, inrush current protection protects the lt3479 against shorts and line transients. during such faults, the inductor current can momentarily exceed 3a and damage the switch. through an internal 8.5m resistor placed in series with the inductor, the inrush current protec- tion comparator measures the inductor current. if it exceeds 5a, a soft-start cycle is initiated. the lt3479 will remain in the soft-start condition until the fault has passed. downloaded from: http:///
lt3479 8 3479fc capacitor selectionlow esr (equivalent series resistance) ceramic capaci- tors should be used at the output to minimize the output ripple voltage. use only x5r or x7r dielectrics, as these materials retain their capacitance over wider voltage and temperature ranges better than other dielectrics. a 4.7f to 10f output capacitor is suf? cient for most high output current designs. converters with lower output currents may need only a 1f or 2.2f output capacitor. table 1. ceramic capacitor manufacturers manufacturer phone web taiyo yuden (408) 573-4150 www.t-yuden.com avx (803) 448-9411 www.avxcorp.com murata (714) 852-2001 www.murata.com inductor selection several inductors that work well with the lt3479 are listed in table 2. however, there are many other manufacturers and devices that can be used. consult each manufacturer for more detailed information and their entire range of parts. ferrite core inductors should be used to obtain the best ef? ciency. choose an inductor that can handle the necessary peak current without saturating, and ensure that the inductor has a low dcr (copper-wire resistance) to minimize i 2 r power losses. a 4.7h or 10h inductor will suf? ce for most lt3479 applications. inductor manufacturers specify the maximum current rating as the current where the inductance falls to some percentage of its nominal valuetypically 65%. an inductor applications information table 2. suggested inductors manufacturer part number i dc (a) inductance (h) max dcr (m) l w h (mm) manufacturer cdrh6d283r0cdrh6d28100 cdrh4d284r7 3 1.7 1.32 3 10 4.7 2465 72 6.7 6.7 3.0 6.7 6.7 3.0 5.0 5.0 3.0 sumida www.sumida.com lm n 05d b4r7mlm n 05d b100k 2.21.6 4.7 10 4910 5.9 6.1 2.8 5.9 6.1 2.8 taiyo yuden www.t-yuden.com lqh55dn4r7m01llqh55dn100m01k 2.71.7 4.7 10 57 130 5.7 5.0 4.7 5.7 5.0 4.7 murata www.murata.com fdv0630-4r7m 4.2 4.7 49 7.0 7.7 3.0 toko www.toko.com figure 1. ef? ciency vs inductor size i out (a) 0 efficiency (%) 70 80 0.8 3479 f01 6050 0.2 0.4 0.6 90 65 75 55 85 sumida cdrh4d28-4r7 toko fdv0630-4r7 can pass a current larger than its rated value without damaging it. aggressive designs where board space is precious will exceed the maximum current rating of the inductor to save board space. consult each manufacturer to determine how the maximum inductor current is measured and how much more current the inductor can reliably conduct. physically larger inductors provide better ef? ciency than smaller ones. figure 1 shows a 3% to 4% ef? ciency gain in using a larger inductor in a 1mhz, 5v to 12v application. the ef? ciency of the toko fdv0630-4r7m, which mea- sures 7mm 7.7mm and 3 mm thick, peaks at 87%. the smaller sumida cdrh4d28-4r7 which is 5mm 5mm and 3mm thick yields a peak ef? ciency of 85% in an identical application. thus, if board space is abundant, then larger inductors should be used to maximize ef? ciency. downloaded from: http:///
lt3479 9 3479fc setting negative output voltages to set a negative output voltage, select the values of r3 and r4 (see figure 3) according to the following equation: vv r r out = ?? ? ?? ? ?. 1 235 3 4 figure 2. positive output voltage feedback connections r2 r1 3479 f02 fbn v ref v out lt3479 fbp figure 3. negative output voltage feedback connections r4 r3 3479 f03 fbp v ref Cv out lt3479 fbn applications information diode selection schottky diodes, with their low forward voltage drop and fast switching speed, are ideal for lt3479 applications. table 3 lists several schottky diodes that work well with the lt3479. the diodes average current rating must exceed the average output current. the diodes maximum reverse voltage must exceed the output voltage. the diode conducts current only when the power switch is turned off (typically less than 50% duty cycle), so a 3a diode is suf? cient for most designs. the companies below also offer schottky diodes with high voltage and current ratings. table 3. suggested diodes manufacturer part number max current (a) max reverse voltage (v) manufacturer ups340ups315 33 4015 microsemi www.microsemi.com b220b230 b240 b320 b330 b340 sbm340 22 2 3 3 3 3 2030 40 20 30 40 40 diodes, inc www.diodes.com setting positive output voltages to set a positive output voltage, select the values of r1 and r2 (see figure 2) according to the following equation: vv r r out =+ ?? ? ?? ? 1 235 1 1 2 . board layoutas with all switching regulators, careful attention must be paid to the pcb board layout and component place- ment. to maximize ef? ciency, switch rise and fall times are made as short as possible. to prevent radiation and high frequency resonance problems, proper layout of the high frequency switching path is essential. minimize the length and area of all traces connected to the sw pin and always use a ground plane under the switching regulator to minimize interplane coupling. the signal path including the switch, output diode d1 and output capacitor c out , contains nanosecond rise and fall times and should be kept as short as possible. recommended component placement is shown in figure 4. soft-start for many applications, it is necessary to minimize the inrush current at start-up. the built-in soft-start circuit signi? cantly reduces the start-up current spike and output voltage overshoot. a typical value is 10nf for 1.65ms. figure 5 shows the start-up output voltage and induc- tor current waveforms in a typical application without a soft-start capacitor. notice the output voltage overshoot and the large initial current. the addition of a 22nf capaci- tor eliminates the output overshoot and reduces the peak inductor current (figure 6). downloaded from: http:///
lt3479 10 3479fc applications information gndgnd ss v c fbn fbp v ref swsw l v s v in r t shdn lt3479 r t r2 c ss r c r1 c c c out d c in c s l1 minimize the area of this trace to v s to v in to gnd to shdn 3479 f04 place vias around exposed pad to enhance thermal performance to v out figure 4. suggested board layout switching frequency the switching frequency of the lt3479 is set by an exter- nal resistor attached to the r t pin. do not leave this pin open. a resistor must always be connected for proper operation. see table 4 and figure 7 for resistor values and corresponding frequencies. table 4. switching frequency switching frequency (mhz) r t (k) 3.5 1.78 3 2.87 2.5 4.32 2 6.49 1.5 10.2 1 17.8 0.5 39.2 0.2 113 figure 5. start-up with no soft-start capacitor 0.2ms/div i l 2a/div v out 5v/div 3479 f05 figure 6. start-up with c ss = 22nf 0.2ms/div i l 2a/div v out 5v/div 3479 f06 downloaded from: http:///
lt3479 11 3479fc increasing switching frequency reduces output voltage ripple but also reduces ef? ciency. the user should set the frequency for the maximum tolerable output voltage ripple. figure 8 shows a reduction in ef? ciency of about 4% between 1mhz and 2mhz operation in a typical application. inrush current protection the lt3479 features a novel inductor current sensing circuit that protects the lt3479 during hot plugging and short circuits. an internal resistor in series with the ex- ternal inductor senses the inductor current at all times. when it exceeds 5a, a soft-start cycle is initiated. figure 9 applications information shows an output overload with inrush current protection disabled. notice that soft-start remains high, and that the inductor current does not return to zero. figure 10 illustrates the bene? ts of inrush current protection. the output short initiates a new soft start cycle reducing the inductor current. after the fault has passed, the inductor current slowly returns to its equilibrium value. to ensure bond wire integrity, the inductor current should not exceed 8a for more than 10ms. bypassing the 8.5m inductor current sense resistor disables inrush current protection. connect the inductor supply trace and bypass capacitor to the l pin and leave the v s pin open to disable this feature. figure 7. switching frequency r t (k) 0 1.51.0 0.5 3.53.0 2.5 2.0 3479 f07 switch frequency (mhz) 0.1 100 10 figure 8. ef? ciency vs switching frequency i out (a) 0 efficiency (%) 70 80 1mhz 0.8 3479 f08 6050 0.2 0.4 0.6 90 65 75 55 85 2mhz 20s/div v sw 10v/div i l 4v/div v ss 2v/div v out 20v/div 3479 f09 figure 9. output overload with inrush current protection enabled 20s/div v sw 10v/div i l 4v/div v ss 2v/div v out 20v/div 3479 f10 figure 10. output overload with inrush current protection disabled figure 11. circuit for output overload lt3479 boost regulator v in 0.5 3479 f11 v out downloaded from: http:///
lt3479 12 3479fc typical applications 200k 23.2k 17.8k 10k c12.2f v in 5v d1 l1 4.7h 3479 ta03 fbn sw lv s v in v c gnd r t v ref shdnss lt3479 fbp 2.2nf c1: taiyo yuden lmk316bj225md c2: avx 1206 yd106mat d1: diodes inc b320a l1: toko fdv0630-4r7m c210f v out 12v0.8a 10nf 5v to 12v/800ma 1mhz boost converter i out (a) 0 efficiency (%) 70 80 0.8 3479 ta03b 6050 0.2 0.4 0.6 90 65 75 55 85 ef? ciency 200k 23.2k 39.2k 4.7k c12.2f v in 5v d1 l1 10h 3479 ta04 fbn sw lv s v in v c gnd r t v ref shdnss lt3479 fbp 10nf c1: taiyo yuden lmk316bj225md c2: avx 1206 yd106mat d1: diodes inc. b320a l1: sumida cdrh8d43-100 c210f v out 12v0.8a 10nf 5v to 12v/800ma 500khz boost converter i out (a) 0 efficiency (%) 70 80 0.8 3479 ta04b 6050 0.2 0.4 0.6 90 65 75 55 85 ef? ciency downloaded from: http:///
lt3479 13 3479fc typical applications 169k 30.9k 17.8k 4.3k c12.2f v in 3.3v d1 l1 4.7h 3479 ta05 fbn sw lv s v in v c gnd r t v ref shdnss lt3479 fbp 10nf c1: taiyo yuden lmk316bj225md c2: avx 1206 yd106mat d1: diodes inc b320a l1: toko fdv0630-4r7m c210f v ou 8v0.9 a 10nf 3.3v to 8v/900ma boost converter i out (a) 0 efficiency (%) 70 80 0.8 3479 ta03b 6050 0.2 0.4 0.6 90 65 75 55 85 ef? ciency 100k 402k 17.8k 1k c12.2f v in 5v 100pf d1 d3 d2 c2 2.2f l1 4.7h 3479 ta06 15nf c1, c2: taiyo yuden lmk316bj225md c3: avx 1206 yd106mat d1, d2: diodes inc b320a d3: central semi, cmdsh-3-ltc l1: toko fdv0630-4r7m c310f v out C5v600ma 10nf fbp sw lv s v in v c gnd r t v ref shdnss lt3479 fbn 5v to C5v/600ma inverting dc/dc converter i out (a) 0 efficiency (%) 70 80 0.8 3479 ta04b 6050 0.2 0.4 0.6 90 65 75 55 85 ef? ciency downloaded from: http:///
lt3479 14 3479fc typical applications c22.2f 0.15 on 3479 ta07 600ma l1 4.7h d1 v in 2.8v to 4.2v 10k 124k 7.5k 10k 2.2nf c1, c2: taiyo yuden lmk316bj225md d1: philips pmeg 2010 d2, d3: lumileds lxhl-pw01 l1: sumida cdrh4d28-4r7 m1: vishay siliconix si2302ads 10nf c12.2f fbn sw lv s v in v ref shdn on m1 ss lt3479 fbp v c r t gnd d2d3 500ma, 12 white led driver downloaded from: http:///
lt3479 15 3479fc typical applications c24.7f i led 500ma 0.150 3479 ta08 l1 10h d1 v in 8v to 16v 1 1 93.1k 5.9k 100k 17.8k 10k 3.3nf c1: taiyo yuden emk316bj475ml c2: taiyo yuden tmk325bj475ml d1: diodes inc b330b d2: lumileds lxhl-nw99 l1: sumida cdrh8d28-100 10nf c14.7f fbn d2 sw lv s v in v ref shdn ss lt3479 fbp v c r t gnd v out 16v to 24v 500ma, 12 white led driver i out (a) 0 efficiency (%) 0.5 3479 ta08b 0.1 0.2 0.3 0.4 100 9080 70 60 50 v in = 8v v in = 12v v in = 16v ef? ciency downloaded from: http:///
lt3479 16 3479fc typical applications 100k 18.7k 17.8k 10k c14.7f c6 0.1f c5 0.1f v in 2.8v to 4.2v l1 3.3h 3479 ta10 fbn sw lv s v in v c gnd r t v ref shdnss lt3479 fbp 2.2nf c222f 8v700ma C8v10ma 16v10ma c4 1f c3 1f 10nf d2a d1 d2b d3b d3a c1: avx 0805zd475mat c2: avx 1210yd226mat c3 to c6: x5r/x7r 10v d1: mbrm120 or equivalent d2, d3: bat54s or equivalent l1: sumida cdrh4d28-3r3 8v, 16v, C8v triple output power supply for tftlcd panels load current (a) 0 efficiency (%) 100 9080 70 60 50 0.2 0.4 0.5 3479 ta10b 0.1 0.3 0.6 0.7 ef? ciency downloaded from: http:///
lt3479 17 3479fc typical applications 3479 ta11 l3 15h 10.2k1.13k 11.3k 10.2k 4.99k 3.3nf d1, d2: diodes inc dfls230 2a, 30vd3: philips 1ps79sb62 l1-l4: sumida cdrh6d38-150 all capacitors x5r/x7r dielectric or equivalent 20nf 4.7f 16v 30f16v fbn sw lv s v in v ref shdn ss lt3479 fbp v c r t gnd l1 15h d1 d2 d3 v in 10v to 14v v out C7v to C10v1a v out 7v to 10v1a 10k 10nf 470pf 470pf 5.76k 26.1k 10.2k 4.99k 3.3nf 4.7f16v 1f 16v 1f 16v 30f16v fbn sw lv s v in v ref shdn ss lt3479 fbp shdn v c r t gnd v ctrl 0v-2.5v l2 15h l4 15h 1a dual tracking power supply with adjustable outputs i out (a) 0 efficiency (%) 8075 70 65 60 55 50 0.2 0.4 0.6 0.8 3479 ta11b 1.0 v in = 14v, v out = 7v v in =10v, v out = 7v v in =14v, v out = 10v ef? ciency downloaded from: http:///
lt3479 18 3479fc package description 3.00 0.10 (2 sides) 4.00 0.10 (2 sides) note:1. drawing proposed to be made variation of version (wged-3) in jedec package outline mo-229 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 0.15mm 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 0.40 0.10 bottom view?exposed pad 1.70 0.10 0.75 0.05 r = 0.115 typ r = 0.05 typ 3.00 ref 1.70 0.05 1 7 14 8 pin 1 top mark (see note 6) 0.200 ref 0.00 ? 0.05 (de14) dfn 0806 rev b pin 1 notchr = 0.20 or 0.35 45 chamfer 3.00 ref recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 2.20 0.05 0.70 0.05 3.60 0.05 packageoutline 0.25 0.05 0.25 0.05 0.50 bsc 3.30 0.05 3.30 0.10 0.50 bsc de package 14-lead plastic dfn (4mm 3mm) (reference ltc dwg # 05-08-1708 rev b) downloaded from: http:///
lt3479 19 3479fc 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. package description fe16 (bc) tssop 0204 0.09 C 0.20 (.0035 C .0079) 0 C 8 0.25 ref 0.50 C 0.75 (.020 C .030) 4.30 C 4.50* (.169 C .177) 134 5 6 7 8 10 9 4.90 C 5.10* (.193 C .201) 16 1514 13 12 11 1.10 (.0433) max 0.05 C 0.15 (.002 C .006) 0.65 (.0256) bsc 2.94 (.116) 0.195 C 0.30 (.0077 C .0118) typ 2 recommended solder pad layout 0.45 ? 0.05 0.65 bsc 4.50 ? 0.10 6.60 ? 0.10 1.05 ? 0.10 2.94 (.116) 3.58 (.141) 3.58 (.141) 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 fe package 16-lead plastic tssop (4.4mm) (reference ltc dwg # 05-08-1663) exposed pad variation bc downloaded from: http:///
lt3479 20 3479fc linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2004 lt 0809 rev c printed in usa related parts typical application part number description comments lt1618 constant current, constant voltage 1.4mhz, high ef? ciency boost regulator v in : 1.6v to 18v, v out(max) = 5.5v, i q = 2.5ma, i sd = <1a, qfn16 package ltc?3216 1a low noise high current led charge pump with independent torch/flash current control v in : 2.9v to 4.4v, v out(max) = 5.5v, i q = 300a, i sd = <1a, dfn12 package ltc3436 3a (i sw ), 1mhz, 34v step-up dc/dc converter v in : 3v to 25v, v out(max) = 34v, i q = 0.9ma, i sd = <6a, tssop16e package ltc3453 synchronous buck-boost high power white led driver v in : 2.7v to 5.5v, v out(max) = 5.5v, i q = 2.5ma, i sd = <1a, qfn16 package lt3466 dual constant current, 2mhz, high ef? ciency white led boost regulator with integratedschottky diode v in : 2.7v to 24v, v out(max) = 40v, i q = 5ma, i sd = <16a, dfn package 115k 10k 2.49k 0.2 i led 500ma/100ma 7.5k 10k c12.2f v in 3.3v to 4.2v d1 d2d3 m1 l1 4.7h 3479 ta09 fbn sw lv s v in v c gnd r t v ref shdn on ss lt3479 fbp 2.2nf c1, c2: taiyo yuden lmk316bj225md d1: philips pmeg2010 d2, d3: lumileds lxhl-pw01 l1: sumida cdrh4d28-4r7 m1: vishay siliconix si2302ads c22.2f on torch modei led = 100ma flash modei led = 500ma 10nf lumiled driver for photo flash with output disconnnect 0.2ms/div v out 1v/div inductor current 0.5a/div 3479 ta09b lumileds start-up 50s/div i led 0.2a/div i led 500ma ? 100ma ? 500ma v out ac-coupled 500mv/div 3479 ta09c lumileds torch/flash transition downloaded from: http:///

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