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1 lt1931/lt1931a 1931fa fixed frequency 1.2mhz/2.2mhz operation very low noise: 1mv p-p output ripple C 5v at 350ma from 5v input C12v at 150ma from 5v input uses small surface mount components wide input range: 2.6v to 16v low shutdown current: <1 a low v cesat switch: 400mv at 1a pin-for-pin compatible with the lt1611 low profile (1mm) thinsot tm package the lt ? 1931/lt1931a are the industrys highest power inverting sot-23 current mode dc/dc converters. both parts include a 1a integrated switch allowing high current outputs to be generated in a small footprint. the lt1931 switches at 1.2mhz while the lt1931a switches at 2.2mhz. these high speeds enable the use of tiny, low cost capacitors and inductors 2mm or less in height. the lt1931 is capable of generating C 5v at 350ma or C12v at 150ma from a 5v supply, while the lt1931a can generate C5v at 300ma using significantly smaller induc- tors. both parts are easy pin-for-pin upgrades for higher power lt1611 applications. the lt1931/lt1931a operate in a dual inductor inverting topology that filters both the input side and output side current. very low output voltage ripple approaching 1mv p-p can be achieved when ceramic output capacitors are used. fixed frequency switching ensures a clean output free from low frequency noise typically present with charge pump solutions. the low impedance output remains within 1% of nominal during large load steps. the 36v switch allows v in to v out differential of up to 34v. the lt1931/lt1931a are available in the 5-lead thinsot package. disk drive mr head bias digital camera ccd bias lcd bias gaas fet bias local low noise/low impedance negative supply 1.2mhz/2.2mhz inverting dc/dc converters in thinsot figure 1. 5v to ?v, 350ma inverting dc/dc converter v in v in 5v v out C5v 350ma 1931 f01 sw l1a 10 h l1b 10 h d1 gnd lt1931 c1: taiyo yuden x5r jmk212bj475mg c2: taiyo yuden x5r lmk212bj105mg c3: taiyo yuden x5r jmk325bj226mm d1: on semiconductor mbr0520 l1: sumida cls62-100 c1 4.7 f c3 22 f c2 1 f r2 10k r1 29.4k c4 220pf nfb shdn load current (ma) 0 50 efficiency (%) 55 65 70 75 100 85 100 200 250 1931 ta01 60 90 95 80 50 150 300 350 efficiency features descriptio u applicatio s u typical applicatio u , ltc and lt are registered trademarks of linear technology corporation. thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners.
2 lt1931/lt1931a 1931fa lt1931 lt1931a parameter conditions min typ max min typ max units minimum operating voltage 2.45 2.6 2.45 2.6 v maximum operating voltage 16 16 v feedback voltage C 1.275 C 1.255 C 1.235 C1.275 C1.255 C1.235 v C 1.280 C 1.230 C1.280 C1.230 v nfb pin bias current v nfb = C1.255v 48 816 a quiescent current v shdn = 2.4v, not switching 4.2 6 5.8 8 ma quiescent current in shutdown v shdn = 0v, v in = 3v 0.01 1 0.01 1 a reference line regulation 2.6v v in 16v 0.01 0.05 0.01 0.05 %/v switching frequency 1 1.2 1.4 1.8 2.2 2.6 mhz 0.85 1.6 1.6 2.9 mhz maximum duty cycle 84 90 75 82 % switch current limit (note 3) 1 1.2 2 1 1.2 2.5 a switch v cesat i sw = 1a 400 600 400 600 mv switch leakage current v sw = 5v 0.01 1 0.01 1 a shdn input voltage, high 2.4 2.4 v shdn input voltage, low 0.5 0.5 v shdn pin bias current v shdn = 3v 16 32 35 70 a v shdn = 0v 0 0.1 0 0.1 a (note 1) v in voltage .............................................................. 16v sw voltage ................................................C 0.4v to 36v nfb voltage ............................................................. C 2v current into nfb pin ............................................ 1ma shdn voltage .......................................................... 16v maximum 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 absolute axi u rati gs w ww u package/order i for atio uu w the denotes specifications which apply over the full operating temperature range, otherwise specifications are t a = 25 c. v in = 3v, v shdn = v in , unless otherwise noted. (note 2) electrical characteristics note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: the lt1931e/lt1931ae are 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. lt1931i/lt1931ai are guaranteed over the C40 c to 85 c temperature range. note 3: current limit guaranteed by design and/or correlation to static test. t jmax = 125 c, ja = 150 c/ w order part number s5 part marking consult ltc marketing for parts specified with wider operating temperature ranges. lt1931es5 lt1931aes5 lt1931is5 lt1931ais5 ltra ltsp ltbzf ltbzg 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/ sw 1 gnd 2 top view s5 package 5-lead plastic tsot-23 nfb 3 5 v in 4 shdn
3 lt1931/lt1931a 1931fa typical perfor a ce characteristics uw quiescent current temperature ( c) C50 quiescent current (ma) 4.5 5.0 5.5 25 75 1931 g01 4.0 3.5 3.0 C25 0 50 6.0 6.5 7.0 100 not switching lt1931a lt1931 temperature ( c) C50 C1.28 C1.27 C1.26 C1.25 C1.24 C1.22 C25 02550 1931 g02 75 100 C1.23 feedback voltage (v) shdn pin voltage (v) 0 C10 shdn pin current ( a) 10 30 50 1 2 34 1931 g03 5 70 90 0 20 40 60 80 6 lt1931a t a = 25 c lt1931 feedback pin voltage shutdown pin current current limit switch saturation voltage oscillator frequency duty cycle (%) 10 current limit (a) 0.8 1.2 90 1931 g04 0.4 0 30 50 70 20 40 60 80 1.6 0.6 1.0 0.2 1.4 t a = 25 c switch current (a) 0 0 v cesat (v) 0.05 0.15 0.20 0.25 0.8 0.45 1931 g05 0.10 0.4 0.2 1.0 0.6 1.2 0.30 0.35 0.40 t a = 25 c temperature ( c) C50 0.5 frequency (mhz) 0.9 1.3 1.7 C25 0 25 50 1931 g06 75 2.1 2.5 0.7 1.1 1.5 1.9 2.3 100 lt1931a lt1931 uu u pi fu ctio s sw (pin 1): switch pin. connect inductor/diode here. minimize trace area at this pin to keep emi down. gnd (pin 2): ground. tie directly to local ground plane. nfb (pin 3): feedback pin. reference voltage is C1.255v. connect resistive divider tap here. minimize trace area. the nfb bias current flows out of the pin. set r1 and r2 according to: for lt r v r out 1931 1 1 255 1 255 2 410 6 : ||C. . ? C = + () for lt a r v r out 1931 1 1 255 1 255 2 810 6 : ||C. . ? C = + () shdn (pin 4): shutdown pin. tie to 2.4v or more to enable device. ground to shut down. v in (pin 5): input supply pin. must be locally bypassed.
4 lt1931/lt1931a 1931fa block diagra w figure 2 operatio u the lt1931 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 2. at the start of each oscillator cycle, the sr latch is set, turning on the power switch q3. a voltage proportional to the switch current is added to a stabilizing ramp and the resulting sum is fed into the positive terminal of the pwm comparator a2. when this voltage exceeds the level at the negative input of a2, the sr latch is reset, turning off the power switch. the level at the negative input of a2 is set by the error amplifier (g m ) and is simply an amplified version of the difference between the feedback voltage and the reference voltage of C1.255v. in this manner, the error amplifier sets the correct peak current level to keep the output in regulation. if the error amplifiers output increases, more current is taken from the output; if it decreases, less current is taken. one function not shown in figure 2 is the current limit. the switch current is constantly monitored and not allowed to exceed the nominal value of 1.2a. if the switch current reaches 1.2a, the sr latch is reset regardless of the state of comparator a2. this current limit protects the power switch as well as various external components connected to the lt1931. the block diagram for the lt1931a is identical except that the oscillator is 2.2mhz and resistors r3 to r6 are one-half the lt1931 values. C + C + latch rq s 0.01 ? sw driver comparator 2 shutdown shdn 4 1 C + ramp generator r c c c 1.2mhz oscillator gnd 1931 bd r6 80k r4 150k r3 30k q2 x10 q1 q3 r5 80k v in v in 5 nfb c pl (optional) r2 (external) r1 (external) v out nfb 3 a2 a1 g m
5 lt1931/lt1931a 1931fa applicatio s i for atio wu uu lt1931a and lt1931 differences: switching frequency the key difference between the lt1931a and lt1931 is the faster switching frequency of the lt1931a. at 2.2mhz, the lt1931a switches at nearly twice the rate of the lt1931. care must be taken in deciding which part to use. the high switching frequency of the lt1931a allows smaller cheaper inductors and capacitors to be used in a given application, but with a slight decrease in efficiency and maximum output current when compared to the lt1931. generally, if efficiency and maximum output current are critical, the lt1931 should be used. if applica- tion size and cost are more important, the lt1931a will be the better choice. in many applications, tiny inexpensive chip inductors can be used with the lt1931a, reducing solution cost. duty cycle the maximum duty cycle (dc) of the lt1931a is 75% compared to 84% for the lt1931. the duty cycle for a given application using the dual inductor inverting topol- ogy is given by: dc v vv out in out = + || ||| | for a 5v to C5v application, the dc is 50% indicating that the lt1931a can be used. a 5v to C16v application has a dc of 76.2% making the lt1931 the right choice. the lt1931a can still be used in applications where the dc, as calculated above, is above 75%. however, the part must be operated in the discontinuous conduction mode so that the actual duty cycle is reduced. inductor selection several inductors that work well with the lt1931 are listed in table 1 and those for the lt1931a are listed in table 2. besides these, there are many other inductors that can be used. consult each manufacturer for detailed information and for their entire selection of related parts. ferrite core inductors should be used to obtain the best efficiency, as core losses at frequencies above 1mhz are much lower for ferrite cores than for powdered-iron units. when using coupled inductors, choose one that can handle at least 1a of current without saturating, and ensure that the inductor has a low dcr (copper-wire resistance) to minimize i 2 r power losses. if using uncoupled inductors, each inductor need only handle one-half of the total switch current so that 0.5a per inductor is sufficient. a 4.7 h to 15 h coupled inductor or a 15 h to 22 h uncoupled inductor will usually be the best choice for most lt1931 designs. for the lt1931a, a 2.2 h to 4.7 h coupled inductor or a 3.3 h to 10 h uncoupled inductor will usually suffice. in certain applications such as the charge pump inverting dc/dc converter, only a single inductor is used. in this case, the inductor must carry the entire 1a switch current. table 1. recommended inductors?t1931 l size part ( h) (l w h) mm vendor cls62-100 10 6.8 6.6 2.5 sumida cr43-150 15 4.5 4.0 3.2 (847) 956-0666 cr43-220 22 www.sumida.com ctx10-1 10 8.9 11.4 4.2 coiltronics ctx15-1 15 (407) 241-7876 www. coiltronics.com lqh3c100k24 10 3.2 2.5 2.0 murata lqh4c150k04 15 (404) 436-1300 www.murata.com table 2. recommended inductors?t1931a l size part ( h) (l w h) mm vendor eljpc3r3mf 3.3 2.5 2.0 1.6 panasonic eljpc4r7mf 4.7 (408) 945-5660 www.panasonic.com clq4d10-4r7 1 4.7 7.6 4.8 1.8 sumida clq4d10-6r8 2 6.8 (847) 956-0666 www.sumida.com lb20164r7m 4.7 2.0 1.6 1.6 taiyo yuden lb20163r3m 3.3 (408) 573-4150 www.t-yuden.com LQH3C4R7K24 4.7 3.2 2.5 2.0 murata lqh4c100k24 10 (404) 436-1300 www.murata.com 1 use drawing #5382-t039 2 use drawing #5382-t041
6 lt1931/lt1931a 1931fa applicatio s i for atio wu uu the inductors shown in table 2 for use with the lt1931a were chosen for their small size. for better efficiency, use similar valued inductors with a larger volume. for in- stance, the sumida cr43 series, in values ranging from 3.3 h to 10 h, will give a lt1931a application a few percentage points increase in efficiency. 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, as they have an extremely low esr and are available in very small packages. x5r dielectrics are preferred, followed by x7r, as these materials retain their capacitance over wide voltage and temperature ranges. a 10 f to 22 f output capacitor is sufficient for most lt1931 applications while a 4.7 f to 10 f capacitor will suffice for the lt1931a. solid tantalum or os-con capacitors can be used, but they will occupy more board area than a ceramic and will have a higher esr. 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 lt1931/lt1931a. a 1 f to 4.7 f input capacitor is sufficient for most applications. table 3 shows a list of several ceramic capacitor manufacturers. consult the manufacturers for detailed information on their entire selection of ceramic parts. table 3. ceramic capacitor manufacturers taiyo yuden (408) 573-4150 www.t-yuden.com avx (803) 448-9411 www.avxcorp.com murata (714) 852-2001 www.murata.com the decision to use either low esr (ceramic) capacitors or the higher esr (tantalum or os-con) capacitors can effect the stability of the overall system. the esr of any capacitor, along with the capacitance itself, contributes a zero to the system. for the tantalum and os-con capaci- tors, this zero is located at a lower frequency due to the higher value of the esr, while the zero of a ceramic capacitor is at a much higher frequency and can generally be ignored. a phase lead zero can be intentionally introduced by placing a capacitor (c4) in parallel with the resistor (r1) between v out and v nfb as shown in figure 1. the frequency of the zero is determined by the following equation. ?= z rc 1 214 ?? by choosing the appropriate values for the resistor and capacitor, the zero frequency can be designed to improve the phase margin of the overall converter. the typical target value for the zero frequency is between 20khz to 60khz. figure 3 shows the transient response of the inverting converter from figure 1 without the phase lead capacitor c4. the phase margin is reduced as evidenced by more ringing in both the output voltage and inductor current. a 220pf capacitor for c4 results in better phase margin, which is revealed in figure 4 as a more damped response and less overshoot. figure 5 shows the transient response when a 22 f tantalum capacitor with no phase lead capacitor is used on the output. the higher output voltage ripple is revealed in the upper waveform as a thicker line. the transient response is adequate which implies that the esr zero is improving the phase margin. v out 20mv/div ac coupled i l1a + i l1b 0.5a/div ac coupled 200ma 100ma load current 100 s/div 1931 f03 figure 3. transient response of inverting converter without phase lead capacitor
7 lt1931/lt1931a 1931fa start-up/soft-start for most lt1931/lt1931a applications, the start-up in- rush current can be high. this is an inherent feature of switching regulators in general since the feedback loop is saturated due to v out being far from its final value. the applicatio s i for atio wu uu regulator tries to charge up the output capacitor as quickly as possible, which results in a large inrush current. fig- ure 6 shows a typical oscillograph of the start-up wave- form for the application of figure 1 starting into a load of 33 ? . the lower waveform shows shdn being pulsed from 0v to 5v. the middle waveform shows the input current, which reaches as high as 0.8a. the total time required for the output to reach its final value is approxi- mately 500 s. for some applications, this initial inrush current may not be acceptable. if a longer start-up time is acceptable, a soft-start circuit consisting of r ss and c ss , as shown in figure 7, can be used to limit inrush current to a lower value. figure 8 shows the relevant waveforms with r ss = 15k and c ss = 33nf. input current, measured at v in , is limited to a peak value of 0.5a as the time required to reach final value increases to 1ms. in figure 9, c ss is v out 20mv/div ac coupled i l1a + i l1b 0.5a/div ac coupled 200ma 100ma load current 100 s/div 1931 f04 figure 4. transient response of inverting converter with 220pf phase lead capacitor v out 0.1v/div ac coupled i l1a + i l1b 0.5a/div ac coupled 200ma 100ma load current 50 s/div 1931 f05 figure 5. transient response of inverting converter with 22 f tantalum output capacitor and no phase lead capacitor v in v in 5v v ss v out v out C5v 1931 f07 sw l1a 10 h current probe l1b 10 h d1 gnd lt1931 c1 4.7 f r ss 15k d2 1n4148 c3 22 f c2 1 f r2 10k r1 29.4k c4 220pf nfb shdn + c ss 33nf/68nf c1: taiyo yuden x5r jmk212bj475mg c2: taiyo yuden x5r lmk212bj105mg c3: taiyo yuden xr5 jmk325bj226mm d1: on semiconductor mbr0520 l1: sumida cls62-100 figure 7. r ss and c ss at shdn pin provide soft-start to lt1931 inverting converter v out 2v/div i in 0.5a/div ac coupled 5v 0v v shdn 500 s/div 1931 f06 figure 6. start-up waveforms for 5v to 5v application (figure 1). no soft-start circuit. v out reaches 5v in 500 s; input current peaks at 800ma
8 lt1931/lt1931a 1931fa increased to 68nf, resulting in a lower peak input current of 350ma with a v out ramp time of 1.6ms. c ss or r ss can be increased further for an even slower ramp, if desired. diode d2 serves to quickly discharge c ss when v ss is driven low to shut down the device. d2 can be omitted, resulting in a soft-stop slow discharge of the output capacitor. 1 2 3 5 4 c2 d1 r2 r1 l1b c1 l1a + + shutdown 1931 f10 Cv out gnd v in c3 v out 2v/div i in 0.5a/div ac coupled 5v 0v v ss 200 s/div 1931 f08 figure 8. r ss = 15k, c ss = 33nf; v out reaches 5v in 1ms; input current peaks at 500ma v out 2v/div i in 0.5a/div ac coupled 5v 0v v ss 500 s/div 1931 f09 figure 9. r ss = 15k, c ss = 68nf; v out reaches 5v in 1.6ms; input current peaks at 350ma figure 10. suggested component placement. note cut in ground copper at d1? cathode applicatio s i for atio wu uu diode selection a schottky diode is recommended for use with the lt1931/ lt1931a. the motorola mbr0520 is a very good choice. where the input to output voltage differential exceeds 20v, use the mbr0530 (a 30v diode). these diodes are rated to handle an average forward current of 0.5 a. in applications where the average forward current of the diode exceeds 0.5a, a microsemi ups5817 rated at 1a is recommended. layout hints the high-speed operation of the lt1931/lt1931a de- mands careful attention to board layout. you will not get advertised performance with careless layout. figure 10 shows the recommended component placement. the ground cut at the cathode of d1 is essential for low noise operation.
9 lt1931/lt1931a 1931fa typical applicatio s u v in v in 5v v out C12v 150ma 1931 ta02 sw l1a 10 h l1b 10 h d1 gnd lt1931 c1: taiyo yuden x5r jmk212bj475mg c2: taiyo yuden x5r tmk316bj105ml c3: taiyo yuden x5r emk325bj106mm d1: on semiconductor mbr0520 l1: sumida cls62-100 c1 4.7 f c3 10 f c2 1 f r2 10k r1 84.5k nfb shdn 5v to ?2v inverting converter load current (ma) 0 50 efficiency (%) 60 70 80 25 50 75 100 1931 ta03 125 90 100 55 65 75 85 95 150 efficiency v in v in 5v v out C5v 300ma 1931 ta04 sw l1 10 h l2 10 h d1 gnd lt1931 c1: taiyo yuden x5r jmk212bj475mg c2: taiyo yuden x5r lmk212bj105mg c3: taiyo yuden x5r jmk212bj226mm d1: on semiconductor mbr0520 l1, l2: murata lqh3c100k04 c1 4.7 f c3 22 f c2 1 f r2 10k r1 29.4k 220pf nfb shdn 5v to 5v inverting converter using uncoupled inductors v in v in 5v v out C5v 300ma 1931 ta05a sw l1 4.7 h l2 4.7 h d1 gnd lt1931a c1: taiyo yuden x5r jmk212bj475mg c2: taiyo yuden x5r lmk212bj105mg c3: taiyo yuden x5r jmk212bj475mg d1: on semiconductor mbr0520 l1, l2: murata lqh3c4r7m24 c1 4.7 f c3 4.7 f c2 1 f r2 10k r1 28.7k c4 180pf nfb shdn load current (ma) 0 50 efficiency (%) 55 65 70 75 100 200 250 1931 ta05b 60 80 50 150 300 350 2.2mhz, 5v to 5v inverting converter efficiency
10 lt1931/lt1931a 1931fa typical applicatio s u v in v in 5v v out C5v 200ma 1931 ta06a sw l1 3.3 h l2 3.3 h d1 gnd lt1931a c1: taiyo yuden x5r jmk212bj225mg c2: taiyo yuden x5r lmk212bj105mg c3: taiyo yuden x5r jmk212bj475mg d1: on semiconductor mbr0520 l1, l2: panasonic eljpc3r3mf c1 2.2 f c3 4.7 f c2 1 f r2 10k r1 28.7k c4 68pf nfb shdn load current (ma) 0 50 efficiency (%) 55 60 65 70 75 80 50 100 150 200 1931 ta06b 250 2.2mhz, 5v to ?v converter uses tiny chip inductors efficiency v in v in 12v v ss sw l1 22 h gnd r2 1k lt1931 nfb shdn r ss 15k r3 25.5k r1 1 ? r4 2.7k c6 1000pf c ss 68nf c1 4.7 f 16v c3 1 f 35v *total output power not to exceed 3.3w c1 to c5: x5r or x7r d1, d2: bav99 or equivalent l1: sumida cr43-220 c5 4.7 f 35v 32 d2 1 1931 ta08 c4 4.7 f 35v v out1 C33v 100ma* com v out2 C66v 48ma* c2 1 f 35v 32 d1 1 slic power supply with 33v and 68v outputs, uses soft-start
11 lt1931/lt1931a 1931fa 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. slic power supply with 21.6v and 65v outputs, uses soft-start typical applicatio s u v in v in 5v v ss sw l1 10 h gnd r2 1k lt1931 nfb shdn r ss 15k r3 16.2k r1 1 ? r4 2.7k c8 1000pf c1 4.7 f 16v c ss 68nf c3 1 f 35v c4 1 f 35v *total output power not to exceed 1.3w c1 to c7: x5r or x7r d1, d2: bav99 or equivalent l1: sumida cr43-100 c7 4.7 f 25v 32 d3 c6 4.7 f 25v 32 1 d2 1 1931 ta09 c5 4.7 f 25v v out1 C21.6v 48ma* com v out2 C 65v 20ma* c2 1 f 35v 32 d1 1 1.50 C 1.75 (note 4) 2.80 bsc 0.30 C 0.45 typ 5 plcs (note 3) datum a 0.09 C 0.20 (note 3) s5 tsot-23 0302 rev b pin one 2.90 bsc (note 4) 0.95 bsc 1.90 bsc 0.80 C 0.90 1.00 max 0.01 C 0.10 0.20 bsc 0.30 C 0.50 ref note: 1. dimensions are in millimeters 2. drawing not to scale 3. dimensions are inclusive of plating 4. dimensions are exclusive of mold flash and metal burr 5. mold flash shall not exceed 0.254mm 6. jedec package reference is mo-193 3.85 max 0.62 max 0.95 ref recommended solder pad layout per ipc calculator 1.4 min 2.62 ref 1.22 ref s5 package 5-lead plastic tsot-23 (reference ltc dwg # 05-08-1635)
12 lt1931/lt1931a 1931fa lt/lt 1005 rev a ? printed in usa ? linear technology corporation 2000 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear-tech.com related parts part number description comments lt1307 single cell micropower 600khz pwm dc/dc converter 3.3v at 75ma from one 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 two 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 thinsot C5v at 150ma from 5v input. tiny sot-23 package lt1613 1.4mhz switching regulator in 5-lead thinsot 5v at 200ma from 3.3v input. tiny sot-23 package lt1615 micropower constant off-time dc/dc converter in 5-lead thinsot 20v at 12ma from 2.5v. tiny sot-23 package lt1617 micropower inverting dc/dc converter in 5-lead thinsot C15v at 12ma from 2.5v. tiny sot-23 package lt1930/lt1930a 1.2mhz/2.2mhz, 1a switching regulators in 5-lead thinsot 5v at 450ma from 3.3v input. tiny sot-23 package burst mode operation is a trademark of linear technology corporation. typical applicatio u 2.2mhz, 12v to 5v converter uses low profile coupled inductor efficiency v in v in 12v v out C5v 450ma 1931 ta07a sw l1a 4.7 h l1b 4.7 h d1 gnd lt1931a c1: taiyo yuden y5v emk212f225zg c2: 0.1 f 25v x5r c3: taiyo yuden x5r jmk212bj475mg d1: on semiconductor mbr0520 l1: sumida clq4d10-4r7 drawing #5382-t039 c1 2.2 f c3 4.7 f c2 0.1 f r2 10k r1 28.7k nfb shdn load current (ma) 0 50 efficiency (%) 55 60 65 70 75 80 100 200 300 400 1931 ta07b 500

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