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lt3585-0/lt3585-1 lt3585-2/lt3585-3 1 3585f photo ash chargers with adjustable input current and igbt drivers the lt ? 3585 series are highly integrated ics designed to charge photo? ash capacitors in digital and ? lm cameras. a new control technique allows for the use of extremely small transformers. each part contains an on-chip high voltage npn power switch. output voltage detection is completely contained within the part, eliminating the need for any discrete zener diodes or resistors. the output volt- age can be adjusted by simply changing the turns ratio of the transformer. the chrg/iadj pin gives full control of the part to the user. driving chrg/iadj low puts the part in low power shutdown. the chrg/iadj pin can also be used to reduce the input current of the charger, useful in extending battery life. the done pin indicates when the part has completed charging. the lt3585 series of parts are housed in tiny 3mm 2mm dfn packages. digital/film camera flash pda/cell phone flash emergency strobe adjustable input current integrated igbt driver no output voltage divider needed uses small transformers: 5.8mm 5.8mm 3mm fast photo? ash charge times charges any size photo? ash capacitor supports operation from single li-ion cell, two aa cells or any supply from 1.5v up to 16v small 10-lead (3mm 2mm) dfn package applicatio s u features descriptio u typical applicatio u fast charge time version input current (ma) normal mode charge time (sec) reduced mode charge time (sec) lt3585-3 800/400 3.3 6.6 lt3585-0 550/275 4.6 9.2 lt3585-2 400/200 5.8 12.6 lt3585-1* 250/115 5.0 14.6 100f capacitor, 320v, v in = v bat = 3.6v *50f capacitor, 320v, v in = v bat = 3.6v , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. a c + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-1 320v danger high voltage! operation by high voltage trained personnel only to gate of igbt 3585 ta01a 50 f photoflash capacitor 0.22 f 4.7 f v in 5v v bat 2 aa or 1 to 2 li-ion 1 2 4 5 1:10:2 20 ? to 160 ? ? ? 2.2 f 600v 1m flashlamp trigger t 1 2 3 lt3585-1 photo? ash charger uses high ef? ciency 2mm tall transformers with tunable igbt gate drive lt3585-1 charging waveform normal input current mode v out 50v/div i in 500ma/div 1sec/div 3585 ta01b v bat = 3.6v c out = 50 f
lt3585-0/lt3585-1 lt3585-2/lt3585-3 2 3585f v in voltage ................................................................16v v batt voltage ............................................................16v sw voltage ...............................................................60v sw pin negative current ...........................................C1a chrg/iadj voltage ...................................................10v igbtpwr voltage .....................................................10v igbtin voltage .........................................................10v igbtpu voltage ........................................................10v igbtpd voltage ........................................................10v done voltage ...........................................................10v current into done pin ............................... 0.2ma/C1ma maximum junction temperature .......................... 125c operating temperature range (note 2) ... C40c to 85c storage temperature range ................... C65c to 125c (note 1) the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v in = v bat = v chrg = 3v unless otherwise noted (note 2). speci? cations are for the lt3585-0, lt3585-1, lt3585-2, lt3585-3 unless otherwise noted. parameter conditions min typ max units quiescent current v chrg = 3v, not switching v chrg = 0v, in shutdown 5 0 8 1 ma a v in voltage range 2.5 16 v v bat voltage range 1.5 16 v switch current limit lt3585-3 (note 3) lt3585-0 (note 3) lt3585-2 (note 3) lt3585-1 (note 3) 1.55 1.1 0.75 0.45 1.7 1.2 0.85 0.55 1.85 1.3 0.95 0.65 a a a a switch v cesat lt3585-3, i sw = 1.4a lt3585-0, i sw = 1a lt3585-2, i sw = 700ma lt3585-1, i sw = 400ma 485 330 230 140 mv mv mv mv v out comparator trip voltage measured as v sw C v bat 31 30.5 31.5 31.5 32 32.5 v v v out comparator overdrive 300ns pulse width 200 400 mv dcm comparator trip voltage measured as v sw C v bat 80 130 180 mv chrg/iadj pin current v chrg = 3v v chrg = 0v 45 0 70 0.1 a a switch leakage current v bat = v sw = 5v, in shutdown 0.01 1 a chrg/iadj minimum enable voltage 1.1 v electrical characteristics absolute axi u rati gs w ww u package/order i for atio uu w top view 11 ddb package 10-lead (3mm 2mm) plastic dfn igbtin igbtpwr gnd v in v bat igbtpu igbtpd sw chrg/iadj done 6 8 7 9 10 5 4 2 3 1 t jmax = 125c, ja = 76c/w exposed pad (pin 11) is gnd, must be soldered to pcb order part number ddb part marking lt3585eddb-0 lt3585eddb-1 lt3585eddb-2 lt3585eddb-3 lclk lclj lclh lcfx order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ consult ltc marketing for parts speci? ed with wider operating temperature ranges.
lt3585-0/lt3585-1 lt3585-2/lt3585-3 3 3585f 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. ratings are for dc levels only. the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v in = v bat = v chrg = 3v unless otherwise noted (note 2). speci? cations are for the lt3585-0, lt3585-1, lt3585-2, lt3585-3 unless otherwise noted. electrical characteristics parameter conditions min typ max units chrg/iadj three-state voltage for reduced input current chrg/iadj > 1.1v then float 1.1 1.28 1.4 v chrg/iadj voltage range for normal input current 1.6 10 v chrg/iadj low voltage 0.3 v delay time for reduced input current mode chrg/iadj pin three stated: v bat = 4.2v, fresh li-ion cell v bat = 2.8v, dead li-ion cell v bat = 3v, fresh 2 aa cells v bat = 2v, dead 2 aa cells 5.2 7.2 6.8 9.5 s s s s minimum chrg/iadj pin low time high low high 20 s done output signal high 100k from v in to done 3 v done output signal low 33a into done pin 120 200 mv done leakage current v done = 3v, done npn off 1 100 na igbtpwr voltage range 2.5 10 v igbt input high level 1.5 v igbt input low level 0.5 v igbt output rise time igbtpu pin, c out = 4000pf, igbtpwr = 5v, igbtin = 0v 1.5v, 10% 90% 0.4 s igbt output fall time igbtpd pin, c out = 4000pf, igbtpwr = 5v, igbtin = 1.5v 0v, 90% 10% 0.13 s note 2: the lt3585 series is guaranteed to meet performance speci? cations from 0c to 85c. speci? cations over the C 40c to 85c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: current limit is guaranteed by design and/or correlation to static test.
lt3585-0/lt3585-1 lt3585-2/lt3585-3 4 3585f typical perfor a ce characteristics uw lt3585-0 charging waveform normal input current mode lt3585-1 charging waveform normal input current mode lt3585-2 charging waveform normal input current mode lt3585-0 curves use figure 11, lt3585-1 curves use figure 12, lt3585-2 curves use figure 13 and lt3585-3 curves use figure 14 unless otherwise noted. v out 50v/div 0.5s/div 3585 g01 v bat = 3.6v c out = 50 f average input current 1a/div v out 50v/div 2s/div 3585 g02 v bat = 3.6v c out = 50 f average input current 500ma/div v out 50v/div 1s/div 3585 g03 v bat = 3.6v c out = 50 f average input current 1a/div lt3585-3 charging waveform normal input current mode lt3585-0 charging waveform reduced input current mode lt3585-1 charging waveform reduced input current mode v out 50v/div 0.5s/div 3585 g04 v bat = 3.6v c out = 50 f average input current 1a/div v out 50v/div 0.5s/div 3585 g05 v bat = 3.6v c out = 50 f average input current 1a/div v out 50v/div 2s/div 3585 g06 v bat = 3.6v c out = 50 f average input current 500ma/div lt3585-2 charging waveform reduced input current mode lt3585-3 charging waveform reduced input current mode charge time* normal input current mode v out 50v/div 1s/div 3585 g07 v bat = 3.6v c out = 50 f average input current 1a/div v out 50v/div 0.5s/div 3585 g08 v bat = 3.6v c out = 50 f average input current 1a/div v bat (v) 2 charge time (seconds) 4 6 10 3585 g09 2 0 4 6 *using rubycon 330v, 50 f photoflash output capacitor (fw series) 8 3 5 7 9 8 3 5 1 7 lt3585-0 lt3585-1 lt3585-2 lt3585-3
lt3585-0/lt3585-1 lt3585-2/lt3585-3 5 3585f typical perfor a ce characteristics uw lt3585-0 curves use figure 11, lt3585-1 curves use figure 12, lt3585-2 curves use figure 13 and lt3585-3 curves use figure 14 unless otherwise noted. charge time* reduced input current mode lt3585-0 input current normal input current mode lt3585-1 input current normal input current mode lt3585-2 input current normal input current mode lt3585-3 input current normal input current mode lt3585-0 input current reduced input current mode lt3585-1 input current reduced input current mode lt3585-2 input current reduced input current mode lt3585-3 input current reduced input current mode v bat (v) 2 charge time (seconds) 15 20 25 57 10 3585 g10 10 5 0 34 6 89 *using rubycon 330v, 50 f photoflash output capacitor (fw series) lt3585-0 lt3585-1 lt3585-2 lt3585-3 v out (v) 0 400 500 700 3585 g11 300 200 100 200 300 100 0 600 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 200 250 300 3585 g12 150 100 100 200 300 50 0 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 200 250 450 3585 g13 150 100 100 200 300 50 0 350 400 300 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 400 500 900 3585 g14 300 200 100 200 300 100 0 700 800 600 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 200 250 350 3585 g15 150 100 100 200 300 50 0 300 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 80 100 120 3585 g16 60 40 100 200 300 20 0 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 200 250 3585 g17 150 100 100 200 300 50 0 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v v out (v) 0 200 250 500 450 3585 g18 150 100 100 200 300 50 0 350 400 300 input current (ma) v bat = 4.2v v bat = 3.6v v bat = 2.5v
lt3585-0/lt3585-1 lt3585-2/lt3585-3 6 3585f lt3585-0 ef? ciency normal input current mode typical perfor a ce characteristics uw lt3585-0 curves use figure 11, lt3585-1 curves use figure 12, lt3585-2 curves use figure 13 and lt3585-3 curves use figure 14 unless otherwise noted. v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g19 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6-1 transformer v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g19 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6s-1 transformer v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g21 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6-1 transformer lt3585-1 ef? ciency normal input current mode lt3585-2 ef? ciency normal input current mode lt3585-3 ef? ciency normal input current mode lt3585-0 ef? ciency reduced input current mode lt3585-1 ef? ciency reduced input current mode v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g23 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6-1 transformer v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g24 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6s-1 transformer lt3585-2 ef? ciency reduced input current mode lt3585-3 ef? ciency reduced input current mode lt3585-0 output voltage v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g25 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using kijima sbl-5.6-1 transformer v bat (v) 2 322 v out (v) 324 326 328 330 3456 3585 g27 78 t a = C40 c t a = 25 c t a = 85 c v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g22 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using tdk ldt565630t-041 transformer v out (v) 50 50 efficiency (%) 60 70 80 90 100 150 200 250 3585 g26 300 v bat = 4.2v v bat = 3.6v v bat = 2.5v using tdk ldt565630t-041 transformer
lt3585-0/lt3585-1 lt3585-2/lt3585-3 7 3585f lt3585-1 output voltage lt3585-2 output voltage lt3585-3 output voltage lt3585-0 switch waveform normal input current mode typical perfor a ce characteristics uw lt3585-0 curves use figure 11, lt3585-1 curves use figure 12, lt3585-2 curves use figure 13 and lt3585-3 curves use figure 14 unless otherwise noted. v bat (v) 2 310 v out (v) 312 314 316 318 322 3 456 3585 g28 78 320 t a = C40 c t a = 25 c t a = 85 c v bat (v) 2 314 v out (v) 316 318 330 322 326 3 456 3585 g29 78 324 t a = C40 c t a = 25 c t a = 85 c v bat (v) 2 320 v out (v) 322 324 326 328 330 3 456 3585 g30 78 t a = C40 c t a = 25 c t a = 85 c v sw 10v/div i pri 1a/div 2 s/div 3585 g31 v bat = 3.6v v out = 100v lt3585-0 switch waveform reduced input current mode v sw 10v/div i pri 1a/div 2 s/div 3585 g32 v bat = 3.6v v out = 100v lt3585-0 switch waveform normal input current mode v sw 10v/div i pri 1a/div 2 s/div 3585 g33 v bat = 3.6v v out = 300v lt3585-0 switch waveform reduced input current mode switch dc current limit* lt3585-0/lt3585-1/lt3585-2/ lt3585-3 switch breakdown voltage v sw 10v/div i pri 1a/div 2 s/div 3585 g34 v bat = 3.6v v out = 300v temperature ( c) C50 0 current limit (a) 0.3 0.6 0.9 1.2 C10 20 *dynamic current limit is higher than dc current limit 60 40 80 3585 g35 1.5 1.8 C30 10 30 lt3585-3 lt3585-0 lt3585-2 lt3585-1 switch voltage (v) 0 switch current (ma) 6 8 10 80 3585 g36 4 2 5 7 9 3 1 0 20 10 40 30 60 70 90 50 100 t a = C40 c t a = 25 c t a = 85 c sw pin is resistive until breakdown voltage due to integrated resistors. this does not increase quiescent current of the part
lt3585-0/lt3585-1 lt3585-2/lt3585-3 8 3585f uu u pi fu ctio s igbtin (pin 1): logic input for the igbt driver. when this pin is driven higher than 1.5v, the output goes high. when the pin is below 0.5v, the output will go low. igbtpwr (pin 2): supply pin for the igbt driver. must be locally bypassed with a good quality ceramic capacitor. the minimum operating voltage for the igbt driver is 2.5v. gnd (pin 3): ground. tie directly to local ground plane. v in (pin 4): input supply pin. must be locally bypassed with a good quality ceramic capacitor. the minimum operating voltage for v in is 2.5v. v bat (pin 5): battery supply pin. must be locally bypassed with a good quality ceramic capacitor. the minimum operating voltage for v bat is 1.5v. done (pin 6): open npn collector indication pin. when target output voltage is reached, npn turns on. this pin needs a proper pull-up resistor or current source. chrg/iadj (pin 7): charge and input current adjust pin. a low (< 0.3v) to high (>1.1v) transition on this pin puts the part into power delivery mode. once the target output voltage is reached, the part will stop charging the output. toggle this pin to start charging again. ground to shut down. to enter into the input current reduction mode, the voltage on this pin should be driven high ( >1.1v ) and then ? oated. (for more information refer to the operation section of this data sheet.) to enter normal mode, the voltage should be driven higher than 1.6v. sw (pin 8): switch pin. this is the collector of the internal npn power switch. minimize the metal trace area connected to this pin to minimize emi. tie one side of the primary of the transformer to this pin. the target output voltage is set by the turns ratio of the transformer. choose turns ratio n by the following equation: n v out = + 2 31 5 . where v out is the desired output voltage. igbtpd (pin 9): pull-down output for igbt gate. connect this pin to the igbt gate. add a series resistor to increase the turn-off time to protect the igbt. igbtpu (pin 10): pull-up output for igbt gate. connect this pin to the gate of the igbt. exposed pad (pin 11): ground. tie directly to local ground plane.
lt3585-0/lt3585-1 lt3585-2/lt3585-3 9 3585f si plified w block diagra w C + C + C + C + 1.25v reference variable delay switch latch reset dominant s driver 20mv rq v out comparator dcm comparator q1 enable master latch chrg/iadj uvlo uvlo 2.5v max v bat q2 1.5v max chip power a5 a4 q q r s one shot igbt drive circuitry r1 2.5k r2 60k v in v in to battery c2 4 6 done 7 igbtpwr 2 igbtin 1 q3 C + 5 sw d1 v out secondary primary t1 ? ? + C + C a3 a2 q1 r m lt3585-3, r m = 12m ? lt3585-0, r m = 17m ? lt3585-2, r m = 24m ? lt3585-1, r m = 36m ? 130mv gnd 3 igbtpu 10 igbtpd 3585 f01 9 8 c1 + c out a1 figure 1
lt3585-0/lt3585-1 lt3585-2/lt3585-3 10 3585f operatio u the lt3585 series of parts operate on the edge of dis- continuous conduction mode. when chrg/iadj is driven higher than 1.1v, the master latch is set. this enables the part to deliver power to the photo? ash capacitor. when the power switch, q1, is turned on, current builds up in the primary of the transformer. when the desired current level is reached, the output of comparator a1 goes high, resetting the switch latch that controls the state of q1, and the output of the dcm comparator goes low. q1 now turns off and the ? yback waveform on the sw node quickly rises to a level proportional to v out . the secondary current ? ows through high voltage diode(s), d1, and into the photo? ash capacitor. when the secondary current decays to zero, the voltage on the sw node collapses. when this voltage reaches 130mv higher than v bat , the output of a3 goes high. this sets the switch latch and the power switch, q1, turns back on. this cycle repeats until the target v out level is reached. when the target v out is reached, the master latch resets and the done pin goes low. the input current of an lt3585 series circuit can be reduced by changing the voltage of the chrg/iadj pin. when this pin is between 1.1v and 1.4v, a time delay is added between when a3 goes high and the switch latch is set, see figure 2. if the part is enabled, and the chrg/ iadj pin is ? oated, internal circuitry drives the voltage on the pin to 1.28v. this allows a single i/o port pin, which can be three-stated, to enable or disable the part as well as place the part into the input current reduction mode. this feature effectively reduces the average input current into the ? yback transformer. the magnitude of the delay decreases with increasing v bat . this causes the reduced average input current to remain relatively ? at with changes in v bat . when chrg/iadj is brought higher than 1.6v, no delay is added. the chrg/iadj pin functionality is shown in figure 3. both v bat and v in have undervoltage lockout (uvlo). when one of these pins goes below its uvlo voltage, the done pin goes low. with an insuf? cient bypass capacitor on v bat or v in , the ripple on the pin is likely to activate uvlo and terminate the charge. the applications circuits in the data sheet suggest values adequate for most applications. the lt3585 series also includes an integrated igbt driver. there are two output pins, igbtpu and igbtpd. the igbtpu pin is used to pull the gate of the igbt up. this should be done quickly to guarantee proper xenon lamp ignition. tie this pin directly to the gate of the igbt. the igbtpd pin is pinned out separately to allow for greater ? exibility in choosing a series resistor between the pin and the gate of the igbt. this resistor can be used to slow down the turn off of the igbt. i pri v sw time v sw time 3585 f02 time i pri time extra delay added (~5.2 s at v bat = 4.2v) normal operation chrg/i adj 1.6v reduced input current chrg/i adj three stated fi gure 3 . b as i c o pera ti on fi gure 2 . n orma l an d r e d uce d i npu t c urren t w ave f orms v out 100v/div done 2v/div chrg/iadj 2v/div lt3585-1 v bat = 3.6v c out = 50 f *must take chrg/iadj pin above 1.1v, then float 1sec/div <0.3v <0.3v <0.3v 3v 3v three state* chrg/iadj pin state 3585 f03
lt3585-0/lt3585-1 lt3585-2/lt3585-3 11 3585f applicatio s i for atio wu uu choosing the right device (lt3585-0/lt3585-1/lt3585-2/lt3585-3) the only difference between the four versions of the lt3585 series is the peak current level. for the fastest possible charge time, use the lt3585-3. the lt3585-1 has the lowest peak current capability, and is designed for applications that need a more limited drain on the batteries. due to the lower peak current, the lt3585-1 can use a physically smaller transformer. the lt3585-0 and lt3585-2 have a current limit in between that of the lt3585-1 and the lt3585-3. transformer design the ? yback transformer is a key element for any lt3585-0/ lt3585-1/lt3585-2/lt3585-3 design. it must be designed carefully and checked that it does not cause excessive cur- rent or voltage on any pin of the part. the main parameters that need to be designed are shown in table 1. the ? rst transformer parameter that needs to be set is the turns ratio, n. the lt3585-0/lt3585-1/lt3585-2/lt3585-3 accomplish output voltage detection by monitoring the ? yback waveform on the sw pin. when the sw voltage reaches 31.5v higher than the v bat voltage, the part halts power delivery. thus, the choice of n sets the target output voltage and changes the amplitude gain of the re? ected voltage from the output to the sw pin. choose n according to the following equation: n v out = + 2 31 5 . where v out is the desired output voltage. the number 2 in the numerator is used to include the forward voltage drop across the output diode(s). thus, for a 320v output, n should be 322/31.5 or 10.2. for a 300v output, choose n equal to 302/31.5 or 9.6. the next parameter that needs to be set is the primary inductance, l pri . choose l pri according to the following formula: l v ni pri out pk ?? ? C 200 10 9 where v out is the desired output voltage. n is the trans- former turns ratio. i pk is 1.4 (lt3585-0), 0.7 (lt3585-1), 1 (lt3585-2) and 2 (lt3585-3). l pri needs to be equal or larger than this value to ensure that the lt3585 series has adequate time to respond to the ? yback waveform. all other parameters need to meet or exceed the recom- mended limits as shown in table 1. a particularly important parameter is the leakage inductance, l leak . when the power switch of the lt3585 series turns off, the leakage inductance on the primary of the transformer causes a voltage spike to occur on the sw pin. the height of this spike must not exceed 50v , even though the absolute maximum rating of the sw pin is 60v. the 60v absolute maximum rating is a dc blocking voltage speci? cation, which assumes that the current in the power npn is zero. figure 4 shows the sw voltage waveform for the circuit of figure 8 (lt3585-0). note that the absolute maximum rating of the sw pin is not exceeded. make sure to check the sw voltage waveform with v out near the target output voltage, as this is the worst-case condition for sw volt- age. figure 5 shows the various limits on the sw voltage during switch turn off. table 1. recommended transformer parameters parameter name typical range lt3585-0 typical range lt3585-1 typical range lt3585-2 typical range lt3585-3 units l pri primary inductance >5 >10 >7 >3.5 h l leak primary leakage inductance 100 to 300 200 to 500 200 to 500 100 to 300 nh n secondary/primary turns ratio 8 to 12 8 to 12 8 to 12 8 to 12 v iso secondary to primary isolation voltage >500 >500 >500 >500 v i sat primary saturation current >1.6 >0.8 >1.0 >2 a r pri primary winding resistance <300 <500 <400 <200 m r sec secondary winding resistance <40 <80 <60 <30
lt3585-0/lt3585-1 lt3585-2/lt3585-3 12 3585f applicatio s i for atio wu uu it is important not to minimize the leakage inductance to a very low level. although this would result in a very low leakage spike on the sw pin, the parasitic capacitance of the transformer would become large. this will adversely affect the charge time of the photo? ash circuit. linear technology has worked with several leading magnetic component man- ufacturers to produce predesigned ? yback transformers for use with the lt3585-0 /lt3585-1/lt3585-2/lt3585-3. table 2 shows the details of several of these transformers. output diode selection the rectifying diode(s) should be low capacitance type with suf? cient reverse voltage and forward current rat- ings. the peak reverse voltage that the diode(s) will see is approximately: v pk(r) = v out + (n ? v bat ) the peak current of the diode is simply: i n lt i n lt pk sec pk sec () () . = () = 2 3585 3 14 358 - 55 1 3585 2 07 -0 - () = () = i n lt i n pk sec pk sec () () . lt3585 1 - () for the circuit of figure 8 with v bat of 5v, v pk(r) is 371v and i pk(sec) is 137ma. the gsd2004s dual silicon diode is recommended for most applications. table 3 shows the various diodes and relevant speci? cations. use the appropriate number of diodes to achieve the necessary reverse breakdown voltage. capacitor selection for the input bypass capacitors, high quality x5r or x7r types should be used. make sure the voltage capability of the part is adequate. must be less than 60v must be less than 50v 3585 f05 a b v sw 0v fi gure 4 . lt3585 sw v o lt age w ave f orm figure 5. new transformer design check table 2. predesigned transformerstypical speci? cations unless otherwise noted for use with transformer designation size (w l h) (mm) lpri (h) lpri leakage (nh ) n r pri (m ) r sec ( ) vendor lt3585-1 lt3585-0/ lt3585-2 sbl-5.6s-1 sbl-5.6-1 5.6 8.5 3.0 5.6 8.5 4.0 24 10 400 max 200 max 10.2 10.2 305 103 55 26 kijima musen hong kong of? ce 852-2489-8266 lt3585-1 lt3585-0 lt3585-1 lt3585-2 lt3585-3 ldt565620st-203 ldt565630t-001 ldt565630t-002 ldt565630t-003 ldt565630t-041 5.8 5.8 2.0 5.8 5.8 3.0 5.8 5.8 3.0 5.8 5.8 3.0 5.8 5.8 3.0 8.2 6 14.5 10.5 4.7 390 max 200 max 500 max 550 max 150 max 10.2 10.4 10.2 10.2 10.4 370 max 100 max 240 max 210 max 90 max 11.2 max 10 max 16.5 max 14 max 6.4 max tdk chicago sales of? ce (847) 803-6100 www.components.tdk.com lt3585-0 lt3585-1 lt3585-2 lt3585-3 ttrn-0530-000-t ttrn-0530-012-t ttrn-0530-021-t ttrn-0530-022-t 5.0 5.0 3.0 5.0 5.0 3.0 5.0 5.0 3.0 5.0 5.0 3.0 6.6 16.0 11.8 4.0 200 max 400 max 300 max 300 max 10.3 10.3 10.3 10.3 128 max 515 max 256 max 102 max 28 max 32 max 37 max 16 max tokyo coil engineering japan of? ce 0426-56-6262 v sw 10v/div 100ns/div 3585 f04 v bat = 3.6v v out = 320v
lt3585-0/lt3585-1 lt3585-2/lt3585-3 13 3585f applicatio s i for atio wu uu igbt drive the igbt is a high current switch for the 100a+ current through the photo? ash lamp. to create a redeye effect or to adjust the light output, the lamp current needs to be stopped or quenched with an igbt before discharging the photo? ash capacitor fully. the igbt device also con- trols the 4kv trigger pulse required to ionize the xenon gas in the photo? ash lamp. figure 8 is a schematic of a fully functional photo? ash application with the lt3585-0 serving as the igbt driver. an igbt driver charges the gate capacitance to start the ? ash. the igbt driver does not need to pull up the gate signi? cantly fast because of the inherently slow nature of the igbt. a rise time of 2s is suf? cient to charge the gate of the igbt and create a trigger pulse. with slower rise times, the trigger circuitry will not have a fast enough edge to create the required 4kv pulse. the fall time of the igbt driver is critical to the fi gure 6 . igbt d r i ver o u t pu t w ith 4000 p f l oa d fi gure 7 . igbt t urn- off d e l ay vs r pd table 3. recommended output diodes part max reverse voltage (v) max continuous forward current (ma) capacitance (pf) vendor gsd2004s (dual diode) 2 300 225 5 vishay (402) 563-6866 www.vishay.com cmsd2004s (dual diode) 2 300 225 5 central semiconductor (631) 435-1110 www.centralsemi.con mmbd3004s (dual diode) 2 350 225 5 diodes, inc (816) 251-8800 www.diodes.com safe operation of the igbt. the igbt gate is a network of resistors and capacitors, as shown in figure 9. when the gate terminal is pulled low, the capacitance closest to the terminal goes low but the capacitance further from the terminal remains high. this causes a smaller portion of the device to handle a larger portion of the current, which can damage the device. the pull-down circuitry needs to pull down slower than the internal rc time constant in the gate of the igbt. this is easily accomplished with a resistor placed in series with the igbtpd pin. the lt3585 series integrated igbt drive circuit is indepen- dent of the charging function and draws its power from the igbtpwr pin. the drive pulls high to within 200mv of igbtpwr and pulls down to 100mv. the circuits switching waveform is shown in figure 6. the rise and fall times are measured using a 4000pf output capacitor. the typical 10% to 90% rise time is 320ns when igbtpwr igbtin 1v/div igbtout 2v/div 500ns/div 3585 f06 i gbtpwr = 5v c out = 4000pf r pd = 50 ? r pd ( ? ) 0 0 fall time ( s) 0.2 0.6 0.8 1.0 2.0 1.4 50 100 3585 f07 0.4 1.6 1.8 1.2 150 200
lt3585-0/lt3585-1 lt3585-2/lt3585-3 14 3585f table 4. recommended igbts part drive voltage (v) breakdown voltage (v) collector current (pulsed) (a) vendor cy25cah-8f* cy25caj-8f* cy25bah-8f cy25baj-8f 2.5 4 2.5 4 400 400 400 400 150 150 150 150 renesas (408) 382-7500 www.renesas.com gt8g133 4 400 150 toshiba semiconductor (949) 623-2900 www.semicon.toshiba.co.jp/eng *packaged in 8-lead vson-8 pacakge. applicatio s i for atio wu uu figure 8. complete xenon circuit emitter 3585 f09 gate figure 9. igbt gate is 5v and igbtin is driven by a 5v signal. the typical 90% to 10% fall time is 125ns but varies with r pd given by figure 7. the igbt driver pulls a peak of 50ma when driving an igbt with minimal quiescent current. in the low state, an active pull-down network is used during the initial transition but is deactivated after an internal time constant. this allows the igbt drivers quiescent current to drop to approximately 0.1a during idle conditions. the pull-down circuit will clamp the output below 0.8v for currents not exceeding 10ma in its idle state. the pull-up network is always active when the igbtin is greater than 1.5v. table 4 is a list of recommended igbt devices for strobe applications. these devices are all packaged in 8-lead tssop packages unless otherwise noted. a c + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-0 320v danger high voltage! operation by high voltage trained personnel only to gate of igbt 3585 f08 c2 50 f photoflash capacitor c3 0.22 f c1 4.7 f v in 5v v bat 2 aa or 1 to 2 li-ion d1 1 2 4 5 t1 1:10:2 r pd 20 to 160 ? ? c4 2.2 f 600v r1 1m flashlamp trigger t 1 2 3
lt3585-0/lt3585-1 lt3585-2/lt3585-3 15 3585f applicatio s i for atio wu uu board layout the high voltage operation of these parts demand care- ful attention to board layout. you will not get advertised performance with careless layout. figure 10 shows the recommended component placement. keep the area for the high voltage end of the secondary as small as possible. also note the larger than minimum spacing for all high voltage nodes in order to meet breakdown voltage requirements for the circuit board. it is imperative to keep the electrical path formed by c1, the primary of t1, and the lt3585 series ic as short as possible. if this path is haphazardly made long, figure 10. lt3585 suggested layout it will effectively increase the leakage inductance of t1, which may result in an overvoltage condition on the sw pin. the chrg/iadj pin trace should be kept as short as possible while minimizing the adjacent edge with the sw pin trace. this will eliminate false toggling of the chrg/iadj pin during sharp transitions on the sw pin. thermal vias should be added underneath the exposed pad, pin 11, to enhance the lt3585s thermal performance. these vias should go directly to a large area of ground plane. acting as a heat sink, the thermal vias/ground plane will lower the devices operating temperature. 1 2 3 4 5 10 9 8 7 6 11 thermal vias igbtin v out d1 (dual diode) photoflash capacitor igbtpwr gnd v in v bat v bat c2 c1 3585 f10 t1 r2 r1 gnd done chrg ? ? to gate of igbt
lt3585-0/lt3585-1 lt3585-2/lt3585-3 16 3585f figure 11. lt3585-0 photo? ash charger uses high ef? ciency 3mm tall transformer + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-0 320v to gate of igbt c1: 4.7 f, 10v, x5r or x7r c2: 0.22 f, 10v, x5r or x7r c out : rubycon 330v, 50 f photoflash output capacitor (fw series) d1: vishay gsd2004s dual diode connected in series r1: pull-up resistor needed if done pin used t1: tdk ldt565630t-001, l pri = 6 h, n = 10.4 3585 f11 c out photoflash capacitor c2 0.22 f c1 4.7 f r1 100k v in 2.5v to 8v done charge v bat 1.5v to 8v d1 t1 1:10.4 r2 20 ? to 160 ? ? ? figure 12. lt3585-1 photo? ash charger uses high ef? ciency 2mm tall transformer + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-1 320v to gate of igbt c1: 4.7 f, 10v, x5r or x7r c2: 0.22 f, 10v, x5r or x7r c out : rubycon 330v, 50 f photoflash output capacitor (fw series) d1: vishay gsd2004s dual diode connected in series r1: pull-up resistor needed if done pin used t1: ltd565620st-203, l pri = 8.2 h, n = 10.2 3585 f12 c out photoflash capacitor c2 0.22 f c1 4.7 f r1 100k v in 2.5v to 8v done charge v bat 1.5v to 8v d1 t1 1:10.2 r2 20 ? to 160 ? ? ? typical applicatio s u
lt3585-0/lt3585-1 lt3585-2/lt3585-3 17 3585f figure 13. lt3585-2 uses high ef? ciency 3mm tall transformers + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-2 320v to gate of igbt c1: 4.7 f, 10v, x5r or x7r c2: 0.22 f, 10v, x5r or x7r rubycon 330v, 50 f photoflash output capacitor (fw series) d1: vishay gsd2004s dual diode connected in series r1: pull-up resistor needed if done pin used t1: tdk ldt565630t-003, l pri = 10.5 h, n = 10.2 3585 f13 c out photoflash capacitor c2 0.22 f c1 4.7 f r1 100k v in 2.5v to 8v done charge v bat 1.5v to 8v d1 t1 1:10.2 r2 20 ? to 160 ? ? ? typical applicatio s u + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-3 320v to gate of igbt c1: 4.7 f, 10v, x5r or x7r c2: 0.22 f, 10v, x5r or x7r rubycon 330v, 50 f photoflash output capacitor (fw series) d1: vishay gsd2004s dual diode connected in series r1: pull-up resistor needed if done pin used t1: tdk ldt565630t-041, l pri = 4.7 h, n = 10.4 3585 f14 c out photoflash capacitor c2 0.22 f c1 4.7 f r1 100k v in 2.5v to 8v done charge v bat 1.5v to 8v d1 t1 1:10.4 r2 20 ? to 160 ? ? ? figure 14. lt3585-3 uses high ef? ciency 3mm tall transformers
lt3585-0/lt3585-1 lt3585-2/lt3585-3 18 3585f typical applicatio s u 5 4 6 1 2 3 u1 v in 3585 f15 to done r3 100k 1/10w 0402 r1 5k 1/10w 0402 r t 100k c t 0.1 f enable to chrg/iadj u1: panasonic up04979 composite transistors figure 15. auto refresh application v out 100v/div chrg/iadj 2v/div enable 2v/div 2sec/div lt3585-1 c out = 50 f enable < 0.3v enable > 1.1v normal op. auto refresh auto refresh enable <0.3v enable >1.1v enable < 0.3v 3585 f16 v out 2v/div ac ripple chrg/iadj 2v/div 200ms/div lt3585-1 c out = 50 f 3585 f17 figure 16. auto refresh basic operation figure 17. v out ac ripple in auto refresh mode the lt3585 series can be auto-refreshed using the addi- tional circuitry shown in figure 15 with its basic operation shown in figure 16. the enable pin is used to enable or disable the auto-refresh charging mode. without an auto-refresh circuit, the output voltage will droop due to output capacitor and output diode leakage currents. the circuit in figure 15 uses the done and chrg/iadj pins to form an open-loop control scheme. the output voltage target is sensed through the done pin with the pfet of u1, panasonic up04979 composite transistor. when the done pin goes low during the v out trip condition, the pfet charges the auto-refresh timing node comprised of r t and c t , and in turn, pulls the chrg/iadj pin low through a nfet and disables the lt3585 series part. the done pin immediately goes high in shutdown, releasing the timing node and allowing the voltage at pins 2 and 3 to decay. after approximately a r t c t time constant, the chrg/iadj pin is released and the lt3585 series part is enabled. this cycle is repeated to maintain a constant dc output voltage. the open-loop control method places a constraint on the control loop dominant time constant, r t ? c t , given by: rc il iv tt pk pri lk bat > 2 2 ?? ? where i lk is the known leakage current, i pk is the trans- former peak primary current, and l pri is the transformer primary inductance. if this condition is not met, a runaway condition could occur. the lt3585 series part would continue to charge the output voltage past the internal output trip voltage. figure 17 shows the ac ripple of a typical auto-refresh circuit with the proper selection of r t and c t .
lt3585-0/lt3585-1 lt3585-2/lt3585-3 19 3585f 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. u package descriptio ddb package 10-lead plastic dfn (3mm 2mm) (reference ltc dwg # 05-08-1722 rev ?) 2.00 0.10 (2 sides) note: 1. drawing conforms to version (wecd-1) in jedec package outline m0-229 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 viewexposed pad 0.64 0.05 (2 sides) 0.75 0.05 r = 0.115 typ r = 0.05 typ 2.39 0.05 (2 sides) 3.00 0.10 (2 sides) 1 5 10 6 pin 1 bar top mark (see note 6) 0.200 ref 0 C 0.05 (ddb10) dfn 0905 rev ? 0.25 0.05 0.50 bsc pin 1 r = 0.20 or 0.25 45 chamfer 0.25 0.05 2.39 0.05 (2 sides) recommended solder pad pitch and dimensions 0.64 0.05 (2 sides) 1.15 0.05 0.70 0.05 2.55 0.05 package outline 0.50 bsc
lt3585-0/lt3585-1 lt3585-2/lt3585-3 20 3585f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2006 lt 0706 ? printed in usa related parts part number description comments ltc ? 3407 dual 600ma (i out ), 1.5mhz, synchronous step-down dc/dc converter 96% ef? ciency, v in : 2.5v to 5.5v, v out : 0.6v to 5v, i q = 40a, converter i sd <1a, 10-lead mse/10-lead dfn packages lt3420/lt3420-1 1.4a/1a, photo? ash capacitor chargers with charges automatic top-off charges 220f to 320v in 3.7 seconds from 5v, automatic top-off v in : 2.2v to 16v, i q = 90a, i sd < 1a, 10-lead ms/10-lead dfn packages ltc3425 3a (i out ), 8mhz, 4-phase synchronous step-up dc/dc converter 95% ef? ciency, v in : 0.5v to 4.5v, v out : 2.4v to 5.25v, i q = 12a, i sd < 1a, 32-lead 5mm 5mm qfn package ltc3440 600ma (i out ), synchronous buck-boost dc/dc converter 95% ef? ciency, v in : 2.5v to 5.5v, v out : 2.5v to 5.5v, converter i q = 25a, i sd < 1a, 10-lead ms/10-lead dfn packages lt3463/lt3463a dual boost (250ma)/inverting (250ma/400ma) dc/dc converter for ccd bias integrated schottkys, v in : 2.4v to 15v, v out(max) = 40v, dc/dc converter for ccd bias, i q = 40a, i sd < 1a, 10-leaddfn package lt3468 photo? ash capacitor charger in thinsot tm package charges 100f to 320v in 4.6 seconds from 3.6v, v in : 2.5v to 16v, i q = 5ma, i sd < 1a, 5-lead tsot-23 package lt3472 dual 34v, 1.2mhz boost (350ma)/inverting (400ma) dc/dc converter for ccd bias integrated schottkys, v in : 2.2v to 16v, v out(max) = 34v, dc/dc converter for ccd bias i q = 2.8ma, i sd < 1a, 10-lead dfn package lt3484-0/lt3484-1 lt3484-2 photo? ash capacitor chargers charges 100f to 320v in 4.6 seconds from 3.6v, lt3484-0 v in : 2.5v to 16v, v bat : 1.8v to 16v, i q = 5ma, i sd < 1a, 6-lead 2mm 3mm dfn package lt3485-0/lt3485-1 lt3485-2/lt3485-3 photo? ash capacitor charger with output voltage monitor and integrated igbt drive charges 100f capacitor to 320v in 2.5 seconds from 3.6v. v in : 1.8v to 10v, i q = 5ma, i sd < 1a, 10-lead 3mm 3mm dfn package thinsot is a trademark of linear technology corporation. u typical applicatio figure 18. lt3585-3 typical application + done chrg/iadj v in igbtpwr igbtin igbtpu igbtpd v bat sw gnd lt3585-3 320v to gate of igbt c1: 4.7 f, 10v, x5r or x7r c2: 0.22 f, 10v, x5r or x7r c out : rubycon 330v, 50 f photoflash output capacitor (fw series) d1: vishay gsd2004s dual diode connected in series r1: pull-up resistor needed if done pin used t1: tokyo coil ttrn-0530-022-t, l pri = 4 h, n = 10.3 3585 f18 c out photoflash capacitor c2 0.22 f c1 4.7 f r1 100k v in 2.5v to 8v done charge v bat 1.5v to 8v d1 t1 1:10.3 r2 20 ? to 160 ? ? ?

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