View LT1618_1944666.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LT1618 1 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. the lt ? 1618 step-up dc/dc converter combines a tradi- tional voltage feedback loop and a unique current feedback loop to operate as a constant-current, constant-voltage source. this fixed frequency, current mode switcher oper- ates from a wide input voltage range of 1.6v to 18v, and the high switching frequency of 1.4mhz permits the use of tiny, low profile inductors and capacitors. the current sense voltage is set at 50mv and can be adjusted using the i adj pin. available in the 10-pin msop package, the LT1618 provides a complete solution for constant-current applications. n led backlight drivers n usb powered boost/sepic converters n input current limited boost/sepic converters n battery chargers , ltc and lt are registered trademarks of linear technology corporation. n accurate input/output current control: 5% over temperature n accurate output voltage control: 1% n wide v in range: 1.6v to 18v n 1.4mhz switching frequency n tiny 10-pin msop package n high output voltage: up to 35v n low v cesat switch: 200mv at 1a applicatio s u features descriptio u typical applicatio u constant-current/ constant-voltage 1.4mhz step-up dc/dc converter january 2001 final electrical specifications efficiency curve usb to 12v boost converter (with selectable 100ma/500ma input current limit) load current (ma) efficiency (%) 1618 ta01b 90 85 80 75 70 65 60 0 40 80 100 20 60 120 140 160 off on shdn i adj v c v in v out 12v sw isn isp fb LT1618 r1 909k r2 107k v in 5v c1 4.7 m f 10nf c2 4.7 m f 1618 ta01a d1 l1 10 m h 3 2 1 9 8 7 gnd 510 4 c1: taiyo yuden jmk212bj475 c2: taiyo yuden emk316bj475 d1: on semiconductor mbr0520 l1: sumida cr43-100 0.1 2k 13k 20k 0v 3.3v 100ma 500ma 0v 3.3v
LT1618 2 v in , shdn voltage ................................................... 18v sw voltage .............................................................. 36v isp, isn voltage ...................................................... 36v i adj voltage ............................................................... 6v fb voltage .............................................................. 1.5v v c voltage .............................................................. 1.5v junction temperature ........................................... 125 c operating temperature range (note 2) .. C 40 c to 85 c storage temperature range ................. C 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c ms10 part marking t jmax = 125 c, q ja = 160 c/w consult factory for parts specified with wider operating temperature ranges. LT1618ems absolute axi u rati gs w ww u package/order i for atio uu w (note 1) electrical characteristics the l denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v in = 1.6v, v shdn = 1.6v, unless otherwise noted. parameter conditions min typ max units input voltage 1.6 18 v quiescent current v shdn = 1.6v, not switching 1.8 2.7 ma v shdn = 0v 0.1 1 m a reference voltage measured at fb pin 1.250 1.263 1.276 v l 1.243 1.263 1.283 v reference voltage line regulation 1.6v < v in < 18v 0.01 0.03 %/v fb pin bias current v fb = 1.263v, v isp = v isn = ov, v in = 1.8v l 2 12 na error amplifier voltage gain 180 v/v error amplifier transconductance d i c = 5 m a 160 m mho error amplifier sink current v fb = 1.35v, v c = 1v 15 m a error amplifier source current v fb = 1.10v, v c = 1v 30 m a current sense voltage (isp, isn) v fb = 0v, v iadj = 0v l 47.5 52.5 mv isp, isn pin bias currents (note 3) v isp = 1.85v, v isn = 1.80v, v iadj = 0v 50 80 m a (isp, isn) common mode minimum voltage 1.8 v switching frequency v fb = 1v 1.25 1.4 1.6 mhz v fb = 0v 550 khz maximum switch duty cycle l 88 92 % switch current limit 1.5 2.1 2.8 a switch v cesat i sw = 1a 200 260 mv order part number ltnh 1 2 3 4 5 fb isn isp i adj gnd 10 9 8 7 6 v c shdn v in sw n/c top view ms10 package 10-lead plastic msop
LT1618 3 typical perfor a ce characteristics uw temperature ( c) ?0 feedback voltage (v) 125 1618 g02 0 75 1.270 1.265 1.260 1.255 1.250 4 2 0 ? ? ?5 25 50 100 voltage current fb pin bias current (na) temperature ( c) ?0 peak current (a) 125 1618 g03 0 75 2.5 2.0 1.5 1.0 0.5 0 ?5 25 50 100 temperature ( c) ?0 current sense voltage (mv) 125 1618 g04 0 75 52 51 50 49 48 ?5 25 50 100 i adj pin voltage (v) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 current sense voltage (mv) 1618 g05 60 50 40 30 20 10 0 temperature ( c) ?0 quiescent current (ma) 125 1618 g06 0 75 2.5 2.0 1.5 1.0 0.5 0 ?5 25 50 100 v in = 18v v in = 1.6v fb pin voltage and bias current switch current limit current sense voltage (i adj pin = 0v) current sense voltage (v isp, isn ) quiescent current switch saturation voltage (v ce, sat ) switch current (a) 0 saturation voltage (mv) 2.0 1618 g01 0.5 1.0 1.5 500 400 300 200 100 0 t j = 125 c t j = 50 c t j = 25 c note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: the LT1618 is guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C 40 c to 85 c operating temperature range are assured by design, characterization, and correlation with statistical process controls. note 3: bias currents flow into the isp and isn pins. electrical characteristics the l denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v in = 1.6v, v shdn = 1.6v, unless otherwise noted. parameter conditions min typ max units switch leakage current switch off, v sw = 5v 0.01 5 m a shdn pin current v shdn = 1.6v 5 20 m a shutdown threshold (shdn pin) 0.3 v start-up threshold (shdn pin) 1v
LT1618 4 pi n fu n ctio n s uuu fb (pin 1): feedback pin. set the output voltage by selecting values for r1 and r2 (see figure 1): rr v v out 12 1 263 1 = ? ? ? ? . isn (pin 2): current sense (C) pin. the inverting input to the current sense amplifier. isp (pin 3): current sense (+) pin. the noninverting input to the current sense amplifier. i adj (pin 4): current sense adjust pin. a dc voltage applied to this pin will reduce the current sense voltage. if this adjustment is not needed, tie this pin to ground. gnd (pin 5): ground pin. tie this pin directly to local ground plane. sw (pin 7 ): switch pin. this is the collector of the internal npn power switch. minimize the metal trace area con- nected to this pin to minimize emi. v in (pin 8): input supply pin. bypass this pin with a capacitor to ground as close to the device as possible. shdn (pin 9): shutdown pin. tie this pin higher than 0.9v to turn on the LT1618; tie below 0.25v to turn it off. v c (pin 10): compensation pin for error amplifier. con- nect a series rc from this pin to ground. typical values are 2k w and 10nf. typical perfor a ce characteristics uw temperature ( c) ?0 switching frequency (mhz) 125 1618 g07 0 75 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 ?5 25 50 100 v in = 18v v in = 1.6v feedback pin voltage (v) switching frequency (mhz) 1.2 1618 g08 0 0.2 0.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0.4 0.6 1.0 t j = 25 c shutdown pin voltage (v) 0 shdn pin current ( a) 20 1618 g09 5 10 15 50 45 40 35 30 25 20 15 10 5 0 t j = 50 c t j = 25 c t j = 125 c switching frequency frequency foldback shdn pin current
LT1618 5 1.4mhz oscillator driver + + + + + 5 s q q1 s r + a1 25 5 10 3 2 8 7 9 1.263v 4 1 shdn i adj gnd v c r c c c v in sw isn isp fb a2 a3 0.02 w c1 c2 r sense v out v in r1 r2 l1 d1 figure 1. LT1618 block diagram block diagra w operatio u the LT1618 uses a constant frequency, current mode control scheme to provide excellent line and load regula- tion. operation can be best understood by referring to the block diagram in figure 1. at the start of each oscillator cycle, the sr latch is set, turning on power switch q1. the signal at the noninverting input of pwm comparator a3 is a scaled-down version of the switch current (summed together with a portion of the oscillator ramp). when this signal reaches the level set by the output of error amplifier a2, comparator a3 resets the latch and turns off the power switch. in this manner, a2 sets the correct peak current level to keep the output in regulation. if the error amplifiers output increases, more current is delivered to the output; if it decreases, less current is delivered. a2 has two inverting inputs, one from the voltage feedback loop, and one from the current feedback loop. whichever inverting input is higher takes precedence, forcing the converter into either a constant-current or a constant-voltage mode. the LT1618 is designed to transition cleanly between the two modes of operation. current sense amplifier a1 senses the voltage between the isp and isn pins and provides a 25 level-shifted version to error amplifier a2. when the voltage between isp and isn reaches 50mv, the output of a1 provides 1.263v to one of the noninverting inputs of a2 and the converter is in constant-current mode. if the current sense voltage exceeds 50mv, the output of a1 will increase causing the output of a2 to decrease, thus reducing the amount of current delivered to the output. in this manner the current sense voltage is regulated to 50mv. similarly, if the fb pin increases above 1.263v, the output of a2 will decrease to reduce the peak current level and regulate the output (constant-voltage mode).
LT1618 6 capacitor selection low esr (equivalent series resistance) capacitors should be used at the output to minimize the output ripple voltage. multilayer ceramic capacitors are an excellent choice. they have an extremely low esr and are available in very small packages. x5r and x7r dielectrics are preferred, as these materials retain their capacitance over wider voltage and temperature ranges than other dielectrics. a 4.7 m f to 10 m f output capacitor is sufficient for high output current designs. converters with lower output currents may need only a 1 m f or 2.2 m f output capacitor. solid tantalum or oscon capacitors can be used, but they will occupy more board area than a ceramic and will have a higher esr applicatio n s i n for m atio n wu u u inductor selection several inductors that work well with the LT1618 are listed in table 1, although there are many other manufacturers and devices that can be used. consult each manufacturer for more detailed information and for their entire selection of related parts. many different sizes and shapes are available. ferrite core inductors should be used to obtain the best efficiency, as core losses at 1.4mhz are much lower for ferrite cores than for the cheaper powdered-iron ones. 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 mini- mize i 2 r power losses. a 4.7 m h or 10 m h inductor will be a good choice for many LT1618 designs. table 1. recommended inductors l max height part ( m h) (m w ) (mm) vendor cdrh5d18-4r1 4.1 57 2.0 sumida cdrh5d18-100 10 124 2.0 (847) 956-0666 cr43-2r2 2.2 71 3.5 www.sumida.com cr43-4r7 4.7 109 3.5 cr43-100 10 182 3.5 cr54-100 10 100 4.8 lqh3c1r0m24 1.0 78 2.0 murata lqh3c2r2m24 2.2 126 2.0 (814) 237-1431 lqh3c4r7m24 4.7 260 2.0 www.murata.com forthe same footprint device. always use a capacitor with a sufficient voltage rating. ceramic capacitors also make a good choice for the input decoupling capacitor, which should be placed as close as possible to the v in pin of the LT1618. a 1 m f to 4.7 m f input capacitor is sufficient for most applications. table 2 shows a list of several ceramic capacitor manufacturers. consult the manufacturers for detailed information on their entire selection of ceramic parts. table 2. recommended ceramic capacitor manufacturers vendor phone url taiyo yuden (408) 573-4150 www.t-yuden.com murata (714) 852-2001 www.murata.com kemet (408) 986-0424 www.kemet.com diode selection schottky diodes, with their low forward voltage drop and fast switching speed, are the ideal choice for LT1618 applications. table 3 shows several schottky diodes that work well with the LT1618. many different manufacturers make equivalent parts, but make sure that the component chosen has a sufficient current rating and a voltage rating greater than the output voltage. the diode conducts cur- rent only when the power switch is turned off (typically less than half the time), so a 0.5a or 1a diode will be sufficient for most designs. the companies below also offer schottky diodes with higher voltage and current ratings. table 3. recommended schottky diodes 1a part 0.5a part vendor phone/url ups120 microsemi (510) 353-0822 ups130 www.microsemi.com ups140 mbrm120 mbr0520 on semiconductor (800) 282-9855 mbrm130 mbr0530 www.onsemi.com mbrm140 mbr0540 b120 b0520 diodes, inc (805) 446-4800 b130 b0530 www.diodes.com b140 b0540
LT1618 7 applicatio n s i n for m atio n wu u u setting output voltage to set the output voltage, select the values of r1 and r2 (see figure 1) according to the following equation. rr v out 12 1 263 1 = ? ? ? ? . for current source applications, use the fb pin for over- voltage protection. pick r1 and r2 so that the output voltage will not go too high if the load is disconnected or if the load current drops below the preset value. typically choose r1 and r2 so that the overvoltage value will be about 20% to 30% higher than the normal output voltage (when in constant-current mode). this prevents the volt- age loop from interfering with the current loop in current source applications. for battery charger applications, pick the values of r1 and r2 to give the desired end of charge voltage. selecting r sense /current sense adjustment use the following formula to choose the correct current sense resistor value (for constant current operation). r sense = 50mv/i max for designs needing an adjustable current level, the i adj pin is provided. with the i adj pin tied to ground, the nominal current sense voltage is 50mv (appearing be- tween the isp and isn pins). applying a positive dc voltage to the i adj pin will decrease the current sense voltage according to the following formula: v vv isense iadj = 1 263 0 8 25 .(.) for example, if 1v is applied to the i adj pin, the current sense voltage will be reduced to about 18mv. this adjustability allows the regulated current to be reduced without changing the current sense resistor (e.g. to adjust brightness in an led driver or to reduce the charge current in a battery charger). if the i adj pin is taken above 1.6v, the output of the error amplifier (the v c pin) will be pulled down and the LT1618 will stop switching. a pulse width modulated (pwm) signal can also be used to adjust the current sense voltage; simply add an rc filterto convert the pwm signal into a dc voltage for the i adj pin. if the i adj pin is not used, it should be tied to ground. do not leave the pin floating. for applications needing only a simple one-step current sense adjustment, the circuit in figure 2 works well. if a large value resistor ( 3 2m w ) is placed between the i adj pin and ground, the current sense voltage will reduce to about 25mv, providing a 50% reduction in current. do not leave the i adj pin open. this method gives a well-regulated current value in both states, and is controlled by a logic signal without the need for a variable pwm or dc control signal. when the nmos transistor is on, the current sense voltage will be 50mv, when it is off, the current sense voltage will be reduced to 25mv. figure 2 LT1618 i adj 2m full current 1618 f02 considerations when sensing input current in addition to regulating the dc output current for current- source applications, the constant-current loop of the LT1618 can also be used to provide an accurate input current limit. boost converters cannot provide output short-circuit protection, but the surge turn-on current can be drastically reduced using the LT1618s current sense at the input. sepics, however, have an output that is dc- isolated from the input, so an input current limit not only helps soft-start the output but also provides excellent short-circuit protection.
LT1618 8 applicatio n s i n for m atio n wu u u figure 3 load v out l1 switch node 1618 ?f03 v in high frequency circulating path when sensing input current, the sense resistor should be placed in front of the inductor (between the decoupling capacitor and the inductor) as shown in the circuits in the typical applications section. this will regulate the average inductor current and maintain a consistent inductor ripple current, which will, in turn, maintain a well regulated input current. do not place the sense resistor between the input source and the input decoupling capacitor, as this may allow the inductor ripple current to vary widely (even though the average input current and the average inductorcurrent will still be regulated). since the inductor current is a triangular waveform (not a dc waveform like the output current) some tweaking of the compensation values (r c and c c on the v c pin) may be required to ensure a clean inductor ripple current while the constant-current loop is in effect. for these applications, the constant- current loop response can usually be improved by reduc- ing the r c value, or by adding a capacitor (with a value of approximately c c /10) in parallel with the r c /c c compen- sation network. frequency compensation the LT1618 has an external compensation pin (v c ), which allows the loop response to be optimized for each applica- tion. an external resistor and capacitor (or sometimes just a capacitor) are placed at the v c pin to provide a pole and a zero (or just a pole) to ensure proper loop compensation. numerous other poles and zeroes are present in the closed loop transfer function of a switching regulator, so the v c pin pole and zero are positioned to provide the best loop response. a thorough analysis of the switching regulator control loop is not within the scope of this data sheet, and will not be presented here, but values of 2k w and 10nf will be a good choice for many designs. for those wishing to optimize the compensation, use the 2k w and 10nf as a starting point. for led backlight applications where a pulse-width modulation (pwm) signal is used to drive the i adj pin, the resistor is usually not included in the compensation network. this helps to provide additional filtering of the pwm signal at the output of the error amplifier (the v c pin). switch node considerations to maximize efficiency, switch rise and fall times are made as short as possible. to prevent radiation and high fre- quency resonance problems, proper layout of the highfrequency switching path is essential. keep the output switch (sw pin), diode and output capacitor as close together as possible. minimize the length and area of all traces connected to the switch pin, and always use a ground plane under the switching regulator to minimize interplane coupling. the high speed switching current path is shown in figure 3. the signal path including the switch, output diode and output capacitor contains nano- second rise and fall times and should be kept as short as possible.
LT1618 9 typical applicatio s u load current (ma) 0 efficiency (%) 80 75 70 65 60 50 100 150 200 1618 ta02b 250 300 4.5w direct broadcast satellite (dbs) power supply with short-circuit protection efficiency lhcp rhcp 0v 3.3v shdn i adj v c v in sw isn isp fb LT1618 r1 100k r2 10k r5 24.9k v in 12v c1 4.7 m f c c 33nf c3 3.3 m f c4 3.3 m f 1618 ta02a d1 l1 33 m h l3 2.2 m h l2 33 m h 3 2 1 9 8 7 gnd 510 4 c1: taiyo yuden emk316bj475 (408) 573-4150 c2: taiyo yuden tmk316bj105 (408) 573-4150 c3, c4: taiyo yuden tmk325bj335 (408) 573-4150 d1: on semiconductor mbrm140 (800) 282-9855 l1, l2: sumida cr54-330 (847) 956-0666 l3: sumida cr43-2r2 (847) 956-0666 0.068 r c 2k c2 1 f q1 mmbt3904 q1 fmmt717 zetex d2 murs110 13.5v/18.5v 22khz network tuning r3 10k r4 1k add 5v
LT1618 10 2-cell white led driver efficiency typical applicatio n s u li ion white led driver efficiency led current (ma) 0 efficiency (%) 20 1618 ta03b 51015 80 75 70 65 60 55 50 45 40 v in = 3v v in = 1.6v output current (ma) 10 efficiency (%) 70 1618 ta05b 30 50 90 85 80 75 70 65 60 55 50 20 40 60 80 v in = 5v v in = 3.3v v in = 2.7v efficiency high power white led driver led current (ma) 0 efficiency (%) 20 1618 ta03b 51015 80 75 70 65 60 55 50 45 40 v in = 3.3v v in = 4.2v v in = 2.7v shdn i adj gnd v c v in sw isn isp fb LT1618 r1 2m r2 121k v in 2.7v to 5v 10khz to 50khz pwm brightness adjust c1 4.7 m f c c 0.1 f c2 1 m f 1618 ?ta05a 0.619 d1 l1 10 m h 80ma 3 2 1 9 87 510 4 r3 5.1k c3 0.1 m f 51 51 51 51 c1: taiyo yuden jmk212bj475 (408) 573-4150 c2: taiyo yuden tmk316bj105 (408) 573-4150 d1: on semiconductor mbr0530 (800) 282-9855 l1: sumida cr43-100 (847) 956-0666 shdn i adj gnd v c v in sw isn isp fb LT1618 r1 2m r2 100k v in 2.7v to 5v 10khz to 50khz pwm brightness adjust c1 4.7 m f c c 0.1 f c2 1 m f 1618 ?ta04a 2.49 d1 l1 10 m h 20ma 3 2 1 9 87 510 4 r3 5.1k c3 0.1 m f c1: taiyo yuden jmk212bj475 (408) 573-4150 c2: taiyo yuden tmk316bj105 (408) 573-4150 d1: on semiconductor mbr0530 (800) 282-9855 l1: sumida clq4d10-100 (847) 956-0666 shdn i adj gnd v c v in sw isn isp fb LT1618 r1 2m r2 160k v in 1.6v to 3v 10khz to 50khz pwm brightness adjust c1 4.7 m f c c 0.1 f c2 1 m f 1618 ?ta03a 2.49 d1 l1 4.7 m h 20ma 3 2 1 9 87 510 4 r3 5.1k c3 0.1 m f c1: taiyo yuden jmk212bj475 (408) 573-4150 c2: taiyo yuden emk316bj105 (408) 573-4150 d1: on semiconductor mbr0520 (800) 282-9855 l1: sumida clq4d10-4r7 (847) 956-0666
LT1618 11 package descriptio u dimensions in inches (millimeters) unless otherwise noted. ms10 package 10-lead plastic msop (ltc dwg # 05-08-1661) typical applicatio s u efficiency 12v boost converter with 500ma input current limit 12v boost converter start-up with input current limit (v in = 1.8v, i load = 40ma) 12v boost converter start-up without input current limit (v in = 1.8v, i load = 40ma) l0ad current (ma) 0 efficiency (%) 120 140 1618 ta06b 40 80 90 85 80 75 70 65 60 20 60 100 160 v in = 5v v in = 3.3v shdn i adj v c v in sw isn isp fb LT1618 r1 909k r2 107k v in 1.8v to 5v c1 4.7 m f 10nf c2 4.7 m f 1618 ?ta06a d1 l1 10 m h 3 2 1 9 8 7 gnd 510 4 0.1 2k v out 12v c1: taiyo yuden jmk212bj475 (408) 573-4150 c2: taiyo yuden emk316bj475 (408) 573-4150 d1: on semiconductor mbr0520 (800) 282-9855 l1: sumida cr43-100 (847) 956-0666 i l1 50 s/div 1618 ta07 v out 5v/div i li 200ma/div 50 s/div 1618 ta08 v out 5v/div i li 200ma/div msop (ms10) 1100 * dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.006" (0.152mm) per side ** dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.006" (0.152mm) per side 0.021 0.006 (0.53 0.015) 0 ?6 typ seating plane 0.007 (0.18) 0.043 (1.10) max 0.007 ?0.011 (0.17 0.27) 0.005 0.002 (0.13 0.05) 0.034 (0.86) ref 0.0197 (0.50) bsc 12 3 45 0.193 0.006 (4.90 0.15) 8 9 10 7 6 0.118 0.004* (3.00 0.102) 0.118 0.004** (3.00 0.102)
LT1618 12 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com ? linear technology corporation 2001 1618i lt/tp 0101 2k ? printed in usa related parts typical applicatio n s u part number description comments lt1307 single cell micropower 600khz pwm dc/dc converter 3.3v at 75ma from 1 cell, msop package lt1316 burst mode tm operation dc/dc with programmable current limit 1.5v minimum, precise control of peak current limit lt1317 2-cell micropower dc/dc with low battery detector 3.3v at 200ma from 2 cells; 600khz fixed frequency lt1610 single cell micropower dc/dc converter 3v at 30ma from 1v; 1.7mhz fixed frequency lt1611 inverting 1.4mhz switching regulator in 5-lead sot-23 C5v at 150ma from 5v input. tiny sot-23 package lt1613 1.4mhz switching regulator in 5-lead sot-23 5v at 200ma from 3.3v input. tiny sot-23 package lt1615 micropower dc/dc converter in 5-lead sot-23 20v at 12ma from 2.5v input. tiny sot-23 package lt1617 micropower inverting dc/dc converter in 5-lead sot-23 C15v at 12ma from 2.5v input. tiny sot-23 package lt1930 1.2mhz boost dc/dc converter in sot-23 5v at 450ma from 3.3v. tiny sot-23 package burst mode is a trademark of linear technology corporation. usb to 5v sepic converter efficiency usb sepic during start-up usb sepic start-up with output shorted load current (ma) 0 efficiency (%) 350 1618 f09b 100 250 80 75 70 65 60 50 150 200 300 1ms/div 1618 ta10 v out 2v/div i in 50ma/div 1ms/div 1618 ta11 v out 2v/div 50ma/div shdn i adj v c v in sw isn isp fb LT1618 r1 316k r2 107k v in 5v c1 4.7 m f 10nf c2 10 m f 1618 ?ta09a d1 l1 10 m h l2 10 m h 3 2 1 9 8 7 gnd 510 4 0.1 2k 13k 20k v out 5v c3 0.47 f i in c1: taiyo yuden jmk212bj475 (408) 573-4150 c2: taiyo yuden jmk316bj106 (408) 573-4150 c3: taiyo yuden emk212bj474 (408) 573-4150 d1: on semiconductor mbr0520 (800) 282-9855 l1: sumida cr43-100 (847) 956-0666 off on 0v 3.3v 100ma 500ma 0v 3.3v

▲Up To Search▲

Price & Availability of LT1618

	To Download LT1618 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .