View LT3485EDD-2TRPBF_4559279.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

lt3485-0/lt3485-1/ lt3485-2/lt3485-3 1 34850123fb features descriptio u photoflash capacitor chargers with output voltage monitor and integrated igbt drive typical applicatio u integrated igbt driver voltage output monitor uses small transformers: 5.8mm 5.8mm 3mm operates from two aa batteries, single cell li-ion or any supply from 1.8v up to 10v no output voltage divider needed no external schottky diode required charges any size photoflash capacitor available in 10-lead (3mm 3mm) dfn applicatio s u digital camera and cell phone flash charger the lt ? 3485 family of photoflash chargers are highly inte- grated ics containing complete charger and igbt drive functions. the patented control technique of the lt3485-x allows it to use extremely small transformers. output voltage detection requires no external circuitry. the turns ratio of the transformer controls the final charge voltage. while charging, the output voltage on the capacitor may be monitored by a microcontroller from the monitor pin. each device contains an on-chip high voltage npn power switch, which can withstand negative voltages on the switch pin without an external schottky diode. the device features a v bat pin, which allows the use of two aa cells to charge the capacitor. the internal circuitry operates from the v in pin. the lt3485-0 has a primary current limit of 1.4a, whereas the lt3485-3, lt3485-2, and lt3485-1 have current limits of 2a, 1a and 0.7a respec- tively. these different current limits result in tightly controlled input currents. the charge pin gives full control of the part to the user. driving charge low puts the part in shutdown. the done pin indicates when the part has completed charging. the lt3485 series of parts are housed in a leadless (3mm 3mm) dfn package. fast charge time version input current (ma) charge time (sec) lt3485-3 750 2.5 lt3485-0 500 3.7 lt3485-2 350 5.5 lt3485-1 225 4.0* v in = v bat = 3.6v 100 f capacitor, 320v. *50 f capacitor lt3485-0 igbtout igbtin v in igbtpwr gnd v mont v bat sw 4.7 f 1:10.2 ? ? v bat 2 aa or 1 to 2 li-ion 0.22 f v cc 5v 320v to micro 1 t c a 2 3 1 2 4 5 3485 ta01 150 f photoflash capacitor 2.2 f 600v 1m charge done trigger flashlamp igbt , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. protected by u.s. patents including 6636021. lt3485-0 charging waveform lt3485-0 photoflash charger uses high efficiency 3mm tall transformers danger high voltage ?operation by high voltage trained personnel only v in = 3.6v c out = 100 f v out 50v/div average input current 0.5a/div 1s/div 3485 ta02
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 2 34850123fb v in voltage .............................................................. 10v v bat voltage ............................................................ 10v sw voltage ................................................... C1v to 50v sw pin negative current ...................................... C0.5a charge voltage ...................................................... 10v igbtin voltage ........................................................ 10v igbtout voltage ..................................................... 10v done voltage .......................................................... 10v igbtpwr voltage .................................................... 10v v mont voltage ......................................................... 10v current into done pin ............................... 0.2ma/C1ma maximum junction temperature .......................... 125 c operating temperature range (note 2) ... C40 c to 85 c storage temperature range .................. C65 c to 125 c absolute axi u rati gs w ww u (note 1) parameter conditions min typ max units quiescent current not switching 5 8 ma v charge = 0v 0 1 a v in voltage range 2.5 10 v v bat voltage range 1.7 10 v switch current limit lt3485-3 1.6 1.7 1.8 a lt3485-0 1.1 1.2 1.3 a lt3485-2 0.75 0.85 0.95 a lt3485-1 0.45 0.55 0.65 a switch v cesat lt3485-3, i sw = 1.5a 310 400 mv lt3485-0, i sw = 1a 210 300 mv lt3485-2, i sw = 700ma 170 225 mv lt3485-1, i sw = 400ma 100 175 mv v out comparator trip voltage measured as v sw C v in 31 31.5 32 v v out comparator overdrive 300ns pulse width 200 400 mv dcm comparator trip voltage measured as v sw C v in 10 45 120 mv charge pin current v charge = 3v 65 100 a v charge = 0v 0 0.1 a electrical characteristics the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v in = v bat = v charge = 3v, unless otherwise noted. package/order i for atio uu w consult ltc marketing for parts specified with wider operating temperature ranges. order part number lt3485edd-0 lt3485edd-1 lt3485edd-2 lt3485edd-3 t jmax = 125 c ja = 43 c/w exposed pad (11) is gnd, must be soldered to pcb top view 11 dd package 10-lead (3mm 3mm) plastic dfn 10 9 6 7 8 4 5 3 2 1 v mont done igbtpwr igbtin igbtout charge v bat v in sw sw dd part marking lbrh lbvn lbvp lbtk 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/
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 3 34850123fb parameter conditions min typ max units switch leakage current v in = v sw = 5v, in shutdown 0.01 1 a charge input voltage high 1v charge input voltage low 0.3 v minimum charge pin low time high low high 20 s done output signal high 100k ? from v in to done 3 v done output signal low 33 a into done pin 140 200 mv done leakage current v done = 3v, done npn off 20 100 na igbt input voltage high 1.5 v igbt input voltage low 0.3 v igbt output rise time c out = 4000pf, igbtpwr = 5v, 10% 90% 450 ns igbt output fall time c out = 4000pf, igbtpwr = 5v, 90% 10% 340 ns v out monitor accuracy sw C v bat = 20v 610 625 640 mv sw C v bat = 30v 920 940 960 mv monitor output current 200 a electrical characteristics the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v in = v bat = v charge = 3v, unless otherwise noted. 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 ltc3485e-x is guaranteed to meet performance specifications from 0 c to 85 c. specifications over the C40 c to 85 c operating temperature range are assured by design, characterization and correlation with statistical process controls.
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 4 34850123fb typical perfor a ce characteristics uw lt3485-0 curves use the circuit of figure 8, lt3485-1 curves use the circuit of figure 9, lt3485-2 use the circuit of figure 10 and lt3485-3 use the circuit of figure 11 unless othe rwise noted. lt3485-1 input current lt3485-2 input current lt3485-3 input current lt3485-0 input current lt3485-1 charging waveform lt3485-0 charging waveform lt3485-2 charging waveform lt3485-3 charging waveform charge time v out 50v/div 0.5s/div v in = 3.6v c out = 50 f 3485 g01 average input current 1a/div v out 50v/div 0.5s/div v in = 3.6v c out = 50 f 3485 g02 average input current 0.5a/div v out 50v/div 0.5s/div v in = 3.6v c out = 50 f 3485 g03 average input current 0.5a/div v out 50v/div 0.5s/div v in = 3.6v c out = 50 f 3485 g04 average input current 1a/div v in (v) 2 0 charge time (seconds) 1 2 3 4 6 3 456 1635 g05 78 5 lt3485-1 lt3485-3 lt3485-2 lt3485-0 c out = 50 f v out (v) 0 input current (ma) 400 500 600 150 250 3485 g06 300 200 50 100 200 300 100 0 2.5v 3.6v 4.2v v out (v) 050 0 input current (ma) 100 250 100 200 250 3485 g07 50 200 150 150 300 2.5v 3.6v 4.2v v out (v) 0 0 input current (ma) 100 200 300 400 50 100 150 200 3485 g08 250 300 2.5v 3.6v 4.2v v out (v) 0 0 input current (ma) 100 300 400 500 200 900 3485 g09 200 100 50 250 300 150 600 700 800 2.5v 3.6v 4.2v
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 5 34850123fb lt3485-1 output voltage lt3485-0 output voltage lt3485-3 efficiency lt3485-0 efficiency lt3485-1 efficiency lt3485-2 efficiency lt3485-2 output voltage lt3485 switch current limits lt3485-3 output voltage v out (v) 50 40 efficiency (%) 50 60 70 80 90 100 150 200 250 3485 g10 300 2.5v 3.6v 4.2v v out (v) 50 40 efficiency (%) 50 60 70 80 90 100 150 200 250 3485 g11 300 2.5v 3.6v 4.2v v out (v) 50 40 efficiency (%) 50 60 70 80 90 100 150 200 250 3485 g12 300 2.5v 3.6v 4.2v v out (v) 50 40 efficiency (%) 50 60 70 80 90 100 150 200 250 3485 g13 300 2.5v 3.6v 4.2v v in (v) 2 317 v out (v) 318 319 320 321 322 3 456 3485 g14 78 C40 c 25 c 85 c v in (v) 2 317 v out (v) 318 319 320 321 322 3 456 3485 g15 78 C40 c 25 c 85 c v in (v) 2 322 v out (v) 323 324 325 326 328 327 3 456 3485 g16 78 C40 c 25 c 85 c v in (v) 2 317 v out (v) 318 319 320 321 322 3 456 3485 g17 78 C40 c 25 c 85 c temperature ( c) C40 C20 0 current limit (ma) 800 2000 0 40 60 3485 g18 400 1600 1200 20 80 100 lt3485-3 lt3485-0 lt3485-2 lt3485-1 typical perfor a ce characteristics uw lt3485-0 curves use the circuit of figure 8, lt3485-1 curves use the circuit of figure 9, lt3485-2 use the circuit of figure 10 and lt3485-3 use the circuit of figure 11 unless othe rwise noted.
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 6 34850123fb lt3485-1 switching waveform lt3485-2 switching waveform lt3485-3 switching waveform lt3485-0 switching waveform lt3485-3 switching waveform lt3485-2 switching waveform lt3485-1 switching waveform lt3485-0/lt3485-1/lt3485-2/ lt3485-3 switch breakdown voltage lt3485-0 switching waveform v sw 10v/div 1 s/div v in = 3.6v v out = 100v 3485 g19 i pri 1a/div v sw 10v/div 1 s/div v in = 3.6v v out = 100v 3485 g20 i pri 1a/div v sw 10v/div 1 s/div v in = 3.6v v out = 100v 3485 g21 i pri 1a/div v sw 10v/div 1 s/div v in = 3.6v v out = 300v 3485 g23 i pri 1a/div v sw 10v/div 1 s/div v in = 3.6v v out = 300v 3485 g24 i pri 1a/div v sw 10v/div 1 s/div v in = 3.6v v out = 300v 3485 g25 i pri 1a/div v sw 10v/div 1 s/div 3485 g26 i pri 2a/div v in = 3.6v v out = 300v switch voltage (v) 0 102030405060708090100 switch current (ma) 3485 g27 10 9 8 7 6 5 4 3 2 1 0 t = C40 c t = 25 c t = 85 c sw pin is resistive until breakdown voltage due to integrated resistors. this does not increase quiescent current of part v in = v charge = 5v typical perfor a ce characteristics uw lt3485-0 curves use the circuit of figure 8, lt3485-1 curves use the circuit of figure 9, lt3485-2 use the circuit of figure 10 and lt3485-3 use the circuit of figure 11 unless othe rwise noted. v sw 10v/div 1 s/div 3485 g22 i pri 2a/div v in = 3.6v v out = 100v
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 7 34850123fb charge (pin 1): charge pin. a low (<0.3v) to high (>1v) transition on this pin puts the part into power delivery mode. once the target voltage is reached, the part will stop charging the output. toggle this pin to start charging again. bringing the pin low (<0.3v) will terminate the power delivery and put the part in shutdown. v bat (pin 2): battery supply pin. must be locally bypassed with a good quality ceramic capacitor. battery supply must be 1.7v or higher. v in (pin 3): input supply pin. must be locally bypassed with a good quality ceramic capacitor. input supply must be 2.5v or higher. sw (pins 4, 5): 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. igbtout (pin 6): output drive for igbt gate. connect this pin to the gate of the igbt. igbtin (pin 7): logic input pin for igbt drive. when this pin is driven higher than 1.5v, the igbt output pin goes high. when the pin is below 0.3v, the output is low. igbtpwr (pin 8): input supply pin. must be locally bypassed with a good quality ceramic capacitor. input supply must be 0.1v higher than the turn-on voltage for the igbt. done (pin 9): open npn collector indication pin. when target output voltage is reached, npn turns on. this pin needs a pull-up resistor or current source. v mont (pin 10): supplies a voltage proportional to the output voltage where 1v is the end of charge voltage. only valid while the part is charging. exposed pad (pin 11): ground. tie directly to local ground plane. uu u pi fu ctio s
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 8 34850123fb to battery c1 c2 r1 2.5k r3 4k enable 1.25v reference lt3485-3: r sense = 0.010 ? lt3485-0: r sense = 0.015 ? lt3485-2: r sense = 0.022 ? lt3485-1: r sense = 0.030 ? sample and hold chip power v mont sw 4, 5 charge primary r4 120k r2 60k t1 d1 secondary v out c out photoflash capacitor 3485 f01 C + C + a2 v out comparator dcm comparator 45mv 20mv driver igbt driver r sense gnd q1 done qq q3 q2 sr one- shot one- shot igbt driver power to gate of igbt to v in to v in igbtin + C a3 one- shot C + a1 s rq + C 9 10 3 2 11 1 8 7 6 20 ? 20k fu ctio al block diagra uu w figure 1
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 9 34850123fb charge pin low. only when the final output voltage is reached will the done pin go low. figure 2 shows these various modes in action. when charge is first brought high, charging commences. when charge is brought low during charging, the part goes into shutdown and v out no longer rises. when charge is brought high again, charging resumes. when the target v out voltage is reached, the done pin goes low and charging stops. finally the charge pin is brought low again so the part enters shutdown and the done pin goes high. 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 insufficient 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 lt3485 v mont pin functions as an output to a microcontroller to communicate the progress of the charge. the v mont pin starts to function at about 0.2v, which corresponds to 64v with a turns ratio of 10.2. when the v mont pin is at 1v, the done pin goes low and the charging terminates. the pins output is only valid when the part is charging. the lt3485 also integrates an igbt drive. the igbtpwr pin supplies the power. the igbt output goes high when igbtin goes high and conversely goes low when igbtin goes low. while igbtin is low, the igbt drive draws no quiescent current from igbtpwr. operatio u the lt3485-0/lt3485-1/lt3485-2/lt3485-3 are designed to charge photoflash capacitors quickly and efficiently. the operation of the part can be best understood by referring to figure 1. when the charge pin is first driven high, a one shot sets both sr latches in the correct state. the power npn device, q1, turns on and current begins ramping up in the primary of transformer t1. comparator a1 monitors the switch current and when the peak current reaches 2a (lt3485-3), 1.4a (lt3485-0), 1a (lt3485-2) or 0.7a (lt3485-1), q1 is turned off. since t1 is utilized as a flyback transformer, the flyback pulse on the sw pin will cause the output of a3 to be high. the voltage on the sw pin needs to be at least 45mv higher than v bat for this to happen. during this phase, current is delivered to the photoflash capacitor via the secondary and diode d1. as the second- ary current decreases to zero, the sw pin voltage will begin to collapse. when the sw pin voltage drops to 45mv above v bat or lower, the output of a3 (dcm comparator) will go low. this fires a one shot which turns q1 back on. this cycle will continue to deliver power to the output. output voltage detection is accomplished via r2, r1, q2, and comparator a2 (v out comparator). resistors r1 and r2 are sized so that when the sw voltage is 31.5v above v bat , the output of a2 goes high which resets the master latch. this disables q1 and halts power delivery. npn transistor q3 is turned on pulling the done pin low, indicating that the part has finished charging. power delivery can only be restarted by toggling the charge pin. the charge pin gives full control of the part to the user. the charging can be halted at any time by bringing the figure 2. halting the charging cycle with the charge pin lt3485-2 v in = 3.6v c out = 50 f v out 100v/div v charge 5v/div v done 5v/div 1s/div 3485 f02
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 10 34850123fb applicatio s i for atio wu u u choosing the right device (lt3485-0/lt3485-1/lt3485-2/lt3485-3) the only difference between the four versions of the lt3485 is the peak current level. for the fastest possible charge time, use the lt3485-3. the lt3485-1 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 lt3485-1 can use a physically smaller transformer. the lt3485-0 and lt3485-2 have a current limit in between that of the lt3485-3 and the lt3485-1. transformer design the flyback transformer is a key element for any lt3485-0/lt3485-1/lt3485-2/lt3485-3 design. it must be designed carefully and checked that it does not cause excessive current or voltage on any pin of the part. the main parameters that need to be designed are shown in table 1. the first transformer parameter that needs to be set is the turns ratio n. the lt3485-0/lt3485-1/lt3485-2/lt3485- 3 accomplish output voltage detection by monitoring the flyback waveform on the sw pin. when the sw voltage reaches 31.5v higher than the v bat voltage, the part will halt power delivery. thus, the choice of n sets the target output voltage as it changes the amplitude of the reflected voltage from the output to the sw pin. choose n accord- ing 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 effect of the 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 ? ?? ? 200 10 9 where v out is the desired output voltage. n is the trans- former turns ratio. i pk is 1.4 (lt3485-0), 0.7 (lt3485-1), 1 (lt3485-2) and 2 (lt3485-3). l pri needs to be equal or larger than this value to ensure that the lt3485-0/lt3485-1/lt3485-2/lt3485-3 has ad- equate time to respond to the flyback waveform. all other parameters need to meet or exceed the recom- mended limits as shown in table 1. a particularly impor- tant parameter is the leakage inductance, l leak . when the power switch of the lt3485-0/lt3485-1/lt3485-2/ lt3485-3 turns off, the leakage inductance on the pri- mary of the transformer causes a voltage spike to occur on the sw pin. the height of this spike must not exceed 40v , even though the absolute maximum rating of the sw pin is 50v. the 50v absolute maximum rating is a dc blocking voltage specification, which assumes that the current in the power npn is zero. figure 3 shows the sw voltage waveform for the circuit of figure 8 (lt3485-0). table 1. recommended transformer parameters typical range typical range typical range typical range parameter name lt3485-0 lt3485-1 lt3485-2 lt3485-3 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 ?
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 11 34850123fb note that the absolute maximum rating of the sw pin is not ex ceeded. make sure to check the sw voltage wave- form with v out near the target output voltage, as this is the worst case condition for sw voltage. figure 4 shows the various limits on the sw voltage during switch turn off. 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 photoflash circuit. linear technology has worked with several leading mag- netic component manufacturers to produce pre-designed flyback transformers for use with the lt3485-0/lt3485- 1/lt3485-2/lt3485-3. table 2 shows the details of sev- eral of these transformers. 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. output diode selection the rectifying diode(s) should be low capacitance type with sufficient reverse voltage and forward current rat- ings. the peak reverse voltage that the diode(s) will see is approximately: vvnv pk r out in ? =+ (? ) applicatio s i for atio wu u u table 2. pre-designed transformers ?typical specifications unless otherwise noted transformer size l pri lpri-leakage r pri r sec for use with name (w l h) mm ( h) (nh) n (m ? )( ? ) vendor lt3485-0/lt3485-2 sbl-5.6-1 5.6 8.5 4.0 10 200 max 10.2 103 26 kijima musen lt3485-1 sbl-5.6s-1 5.6 8.5 3.0 24 400 max 10.2 305 55 hong kong office 852-2489-8266 (ph) kijimahk@netvigator.com (email) lt3485-0 ldt565630t-001 5.8 5.8 3.0 6 200 max 10.4 100 max 10 max tdk lt3485-1 ldt565630t-002 5.8 5.8 3.0 14.5 500 max 10.2 240 max 16.5 max chicago sales office lt3485-2 ldt565630t-003 5.8 5.8 3.0 10.5 550 max 10.2 210 max 14 max (847) 803-6100 (ph) lt3485-3 ldt565630t-041 5.8 5.8 3.0 4.7 150 max 10.4 90 max 6.4 max www.components.tdk.com lt3485-0/lt3485-1 t-15-089 6.4 7.7 4.0 12 400 max 10.2 211 max 27 max tokyo coil engineering lt3485-1 t-15-083 8.0 8.9 2.0 20 500 max 10.2 675 max 35 max japan office lt3485-3 t-17-109a 6.5 7.9 4.0 5.9 300 max 10.2 78 max 18.61 max 0426-56-6262 (ph) www.tokyo-coil.co.jp figure 4. new transformer design check (not to scale) figure 3. lt3485 sw voltage waveform i pri 1a/div v sw 10a/div v in = 5v v out = 320v 100ns/div 3485 f03 2 v sw 3485 f04 0v ? ? must be less than 40v must be less than 50v
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 12 34850123fb applicatio s i for atio wu u u the peak current of the diode is simply: i= 2 n lt3485-3 i= 1.4 n lt3485-0 pk-sec pk-sec () ( )) () i= 1 n lt3485-2 i= 0.7 n lt3485- pk-sec pk-sec 11 () f or 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 lt3485-0/lt3485-1/lt3485- 2/lt3485-3 applications. another option is to use the bav23s dual silicon diodes. table 3 shows the various diodes and relevant specifications. use the appropriate number of diodes to achieve the necessary reverse break- down voltage. igbt drive the igbt is a high current switch for the 100a+ current through the photoflash 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 photoflash capacitor fully. the igbt device also con- trols the 4kv trigger pulse required to ionize the xenon gas in the photoflash lamp. figure 5 is a schematic of a fully functional photoflash application with the lt3485 serving as the igbt drive. an igbt drive charges the gate capaci- tance to start the flash. the igbt drive does not need to pull-up the gate fast because of the inherently slow nature of the igbt. a rise time of 2 s is sufficient 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 drive is critical to the safe operation of the igbt. the igbt gate is a network of resistors and capacitors, as shown in figure 6. when the gate terminal is pulled low, table 3. recommended output diodes max reverse voltage max forward continuous current capacitance part (v) (ma) (pf) vendor gsd2004s 2x300 225 5 vishay (dual diode) (402) 563-6866 www.vishay.com bav23s 2x250 225 5 philips semiconductor (dual diode) (800) 234-7381 www.philips.com mmbd3004s 2x350 225 5 diodes inc (dual diode) (816) 251-8800 www.diodes.com figure 5. complete xenon circuit lt3485-0 igbtout igbtin v in igbtpwr gnd v mont v bat sw 4.7 f 1:10.2 ? ? v bat 2 aa or 1 to 2 li-ion 0.22 f v cc 5v 320v to micro 1 t c a 2 3 1 2 4 5 3485 f05 150 f photoflash capacitor 2.2 f 600v 1m charge done trigger flashlamp igbt
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 13 34850123fb applicatio s i for atio wu u u table 4. recommended igbts drive breakdown collector voltage voltage current part (v) (v) (pulsed) (a) vendor cy25bah-8f 2.5 400 150 renesas cy25baj-8f 4 400 150 (408) 382-7500 www.renesas.com gt8g133 4 400 150 toshiba semiconductor (949) 623-2900 www.semicon.toshiba.co.jp/eng/ the capacitance closest to the terminal goes low but the capacitance further from the terminal remains high. this causes a small portion of the device to handle the full 100a of current, which quickly destroys 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 in series with the igbt drive, which is integrated into the lt3485. the lt3485s integrated drive circuit is independent of the charging function. the igbt section draws its power from the igbtpwr pin. the rise and fall times are measured using a 4000pf output capacitor. the typical 10% to 90% rise time is 270ns. the drive pulls high to igbtpwr. the typical 90% to 10% fall time is 180ns. the drive pulls down to 300mv. the igbt driver pulls a peak of 150ma when driving an igbt and 2ma of quiescent current. in the low state, the igbts quiescent current is less than 0.1 a. table 4 is a list of recommended igbt devices for strobe applications. these three devices are all packaged in 8-lead tssop packages. v out monitor the voltage output monitor is a new feature to monitor the progress of capacitor charging with a microcontroller. the monitor uses the flyback waveform to output a voltage proportional to the output of the flyback converter. the output monitor voltage range for the pin is 0v to 1v. the 1v output corresponds with the charge cycle termi- nating and the done pin going low. the voltage output monitor is only functional when the circuit is charging (done and charge are high.) gate emitter 3485 f06 figure 6. igbt gate
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 14 34850123fb applicatio s i for atio wu u u figure 7. suggested layout: keep electrical path formed by c1, transformer primary and lt3485-0/lt3485-1/lt3485-2/lt3485-3 short board layout the high voltage operation of the lt3485-0/lt3485-1/ lt3485-2/lt3485-3 demands careful attention to board layout. you will not get advertised performance with careless layout. figure 7 shows the recommended com- ponent 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 lt3485-0/lt3485-1/ lt3485-2/lt3485-3 as short as possible. if this path is haphazardly made long, it will effectively increase the leakage inductance of t1, which may result in an overvolt- age condition on the sw pin. c out photoflash capacitor charge done igbtpwr v bat c2 c3 t1 c1 v mont igbtin igbtout d1 (dual diode) + secondary primary v in ? ? 1 10 9 2 r1 3485 f07 3 8 11 7 4 5 6
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 15 34850123fb figure 8. lt3485-0 photoflash charger uses high efficiency 4mm tall transformer figure 9. lt3485-1 photoflash charger uses high efficiency 3mm tall transformer typical applicatio s u c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f r1 100k t1 1:10.2 v bat 1.8v to 8v 320v 3485 f08 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: kijima musen part# sbl-5.6-1, l pri = 10 h, n = 10.2 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in v mont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-0 gnd v bat sw c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f r1 100k t1 1:10.2 v bat 1.8v to 8v 320v 3485 f09 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: kijima musen part# sbl-5.6s-1, l pri = 24 h, n = 10.2 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in v mont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-1 gnd v bat sw
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 16 34850123fb figure 11. lt3485-3 photoflash charger uses high efficiency 3mm tall transformer figure 10. lt3485-2 photoflash charger uses high efficiency 4mm tall transformer typical applicatio s u c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f r1 100k t1 1:10.2 v bat 1.8v to 8v 320v 3485 f10 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: kijima musen part# sbl-5.6-1, l pri = 10 h, n = 10.2 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in vmont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-2 gnd v bat sw c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f r1 100k t1 1:10.2 v bat 1.8v to 8v 320v 3485 f11 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: tdk ldt565630t-041, l pri = 4.7 h, n = 10.4 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in v mont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-3 gnd v bat sw
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 17 34850123fb typical applicatio s u figure 12. lt3485-0 photoflash circuit uses tiny 3mm tall transformer figure 13. charge time with tdk transformers (figures 11, 12, 13, 14 and 15) c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f t1 1:10.2 v bat 1.8v to 8v 320v 3485 f12 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: tdk ldt565630t-001, l pri = 6 h, n = 10.4 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in v mont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-0 gnd v bat sw v in (v) 2 0 charge time (seconds) 1 2 3 4 6 3 456 3485 f13 78 5 lt3485-3 lt3485-0 lt3485-1 c out = 50 f lt3485-2
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 18 34850123fb figure 14. lt3485-1 photoflash circuit uses tiny 3mm tall transformer figure 15. lt3485-2 photoflash circuit uses tiny 3mm tall transformer typical applicatio s u c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f t1 1:10.2 v bat 1.8v to 8v 320v 3485 f14 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: tdk ldt565630t-002, l pri = 14.5 h, n = 10.2 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in vmont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-1 gnd v bat sw c2 0.22 f v in 2.5v to 8v done charge c1 4.7 f t1 1:10.2 v bat 1.8v to 8v 320v 3485 f15 c out photoflash capacitor c1: 4.7 f, x5r or x7r, 10v c2: 0.22 f, x5r or x7r, 10v t1: tdk ldt565630t-003, l pri = 10 h, n = 10.2 d1: diodes inc mmbd3004s dual diode connected in series r1: pull up resistor needed if done pin used d1 charge v in vmont to micro to gate of igbt igbtout igbtpwr igbtin done lt3485-2 gnd v bat sw
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 19 34850123fb 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-2). check the ltc website data sheet for current status of variation assignment 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 0.38 0.10 bottom viewexposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.38 0.10 (2 sides) 1 5 10 6 pin 1 top mark (see note 6) 0.200 ref 0.00 C 0.05 (dd10) dfn 1005 0.25 0.05 2.38 0.05 (2 sides) recommended solder pad pitch and dimensions 1.65 0.05 (2 sides) 2.15 0.05 0.50 bsc 0.675 0.05 3.50 0.05 package outline 0.25 0.05 0.50 bsc u package descriptio 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. dd package 10-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1699)
lt3485-0/lt3485-1/ lt3485-2/lt3485-3 20 34850123fb related parts part number description comments ltc3407 dual 600ma (i out ), 1.5mhz, synchronous step-down dc/dc 96% efficiency, v in : 2.5v to 5.5v, v out(min) = 0.6v, i q = 40 a, converter i sd <1 a, ms10e lt3420/lt3420-1 1.4a/1a, photoflash capacitor chargers with charges 220 f to 320v in 3.7 seconds from 5v, automatic top-off v in : 2.2v to 16v, i q = 90 a, i sd < 1 a, ms10 ltc3425 5a i sw , 8mhz, multi-phase synchronous step-up dc/dc 95% efficiency, v in : 0.5v to 4.5v, v out(min) = 5.25v, i q = 12 a, converter i sd < 1 a, qfn-32 ltc3440 600ma/1a (i out ), synchronous buck-boost dc/dc 95% efficiency, v in : 2.5v to 5.5v, v out(min) = 2.5v to 5.5v, converter i q = 25 a, i sd < 1 a, ms-10 dfn-12 lt3468/lt3468-1/ photoflash capacitors in thinsot? charges 110 f to 320v in 4.6 seconds from 3.6v, lt3468-2 v in : 2.5v to 16v, i q = 5ma, i sd < 1 a, thinsot lt3472 dual 34v, 1.2mhz boost (350ma)/inverting (400ma) integrated schottkys, v in : 2.2v to 16v, v out(max) = 34v, dc/dc converter for ccd bias i q = 2.5ma, i sd < 1 a, dfn lt3463/lt3463a dual boost (250ma)/inverting (250ma/400ma) integrated schottkys, v in : 2.3v to 15v, v out(max) = 40v, dc/dc converter for ccd bias i q = 40 a, i sd < 1 a, dfn lt3484-0/lt3484-1/ photoflash capacitor chargers charges 110 f to 320v in 4.6 seconds from 3.6v, lt3484-2 v in : 2.5v to 16v, v bat : 1.8v to 16v, i q = 5ma, i sd < 1 a, 2mm 3mm dfn thinsot is a trademark of linear technology corporation. linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2005 lt 0406 rev b ?printed in usa

▲Up To Search▲

Price & Availability of LT3485EDD-2TRPBF

	To Download LT3485EDD-2TRPBF Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .