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1 for more information www.linear.com/3539/3539-2 typical application features applications description 2a, 1mhz/2mhz synchronous step-up dc/dc converters the lt c ? 3539/ltc3539-2 are synchronous , 2 a step-up dc/dc converters with output disconnect. synchronous rectification enables high efficiency in the low profile 2mm 3 mm dfn package. battery life is extended with a 700 mv start-up voltage and operation down to 500mv once started. a switching frequency of 1 mhz ( ltc3539) or 2mhz (ltc3539-2) minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. the current mode pwm design is internally compensated, reducing external parts count. the ltc3539/ltc3539-2 feature a pin-enabled automatic burst mode operation at light load conditions. anti-ring circuitry reduces emi by damping the inductor in discontinuous mode. additional features include a low shutdown current of under 1 a and thermal overload protection. the ltc3539/ltc3539-2 are offered in a 2 mm 3 mm 0.75mm dfn package. wide v in , high power 3.3v regulator n delivers 3.3 v at 900ma from 2 alkaline/ nimh cells n delivers 5v at 900ma from a lithium-polymer battery n v in start-up voltage: 700mv n 1.5v to 5.25v v out range n up to 94% efficiency n v in > v out operation n 1.5% feedback v oltage tolerance n 1mhz (ltc3539) or 2mhz (ltc3539-2) fixed frequency operation n output disconnect n selectable burst mode ? or pwm operation n 10a quiescent current n logic controlled shutdown: <1a n requires only 6 external components n low profile (2mm 3mm 0.75mm) dfn package n medical instruments n portable bar code scanners n noise canceling headphones n portable gps navigation n handheld pcs l, lt , lt c , lt m and burst mode are registered trademarks and thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. i load average (ma) 0.1 1 10 100 1000 0.1 1 10 100 1000 efficiency (%) power loss (mw) 100 80 60 40 20 0 90 70 50 30 10 3539 ta01b power loss efficiency v in = 2.4v v out = 3.3v frequency = 1mhz frequency = 2mhz efficiency and power loss vs load current 3539 ta01a ltc3539 v in sw 2.2f v out 3.3v 600ma v in 1.8v to 3.6v 4.7h v out mode shdn fb pgnd gnd 562k 1m 22f 2 33pf burst pwm onoff ltc 3539/ ltc 3539-2 35392fc
2 for more information www.linear.com/3539/3539-2 pin configuration absolute maximum ratings v in voltage ................................................... C 0.3 v to 6v sw voltage dc ............................................................ C 0.3 v to 6v pulsed < 100 ns ......................................... C 0.3 v to 7v shdn , fb , mode voltage ............................ C 0.3 v to 6v v out ............................................................. C0. 3 v to 6v operating temperature ( notes 2, 5) ......... C 40 c to 85 c storage temperature range .................. C 65 c to 125 c (note 1) top view v out mode fb shdn sw pgnd gnd v in dcb package 8-lead (2mm 3mm) plastic dfn 9 3 4 2 1 6 5 7 8 t jmax = 125c, ja = 64c/w (note 6) exposed pad ( pin 9) is gnd, must be soldered to pcb order information electrical characteristics parameter conditions min typ max units input voltage range after start-up 0.5 5 v minimum start-up voltage i load = 1ma, v out = 0v 0.7 0.88 v output voltage adjust range l 1.5 5.25 v feedback voltage l 1.182 1.200 1.218 v feedback input current v fb = 1.2v 1 50 na quiescent current - shutdown v shdn = 0v, not including switch leakage, v out = 0v 0.01 1 a quiescent current - active measured on v out , non-switching 300 500 a quiescent current - burst measured on v out , fb > 1.230v 10 18 a n-channel mosfet switch leakage current v sw = 5v 0.1 10 a p-channel mosfet switch leakage current v sw = 5v, v out = 0v 0.1 20 a n-channel mosfet switch on resistance v out = 3.3v 0.09 p-channel mosfet switch on resistance v out = 3.3v 0.125 n-channel mosfet current limit l 2 2.6 a the l denotes the specifications which apply over the specified temperature range of C40c to 85c, otherwise specifications are at t a = 25c. v in = 1.2v, v out = 3.3v, unless otherwise noted. lead free finish tape and reel part marking package description temperature range ltc3539edcb#pbf ltc3539edcb#trpbf ldcs 8-lead (2mm 3mm) plastic dfn C40c to 85c ltc3539edcb-2#pbf ltc3539edcb-2#trpbf ldph 8-lead (2mm 3mm) plastic dfn C40c to 85c consult lt c marketing for parts specified with wider operating temperature ranges. consult lt c marketing for information on non-standard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ltc 3539/ ltc 3539-2 35392fc
3 for more information www.linear.com/3539/3539-2 electrical characteristics note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the ltc3539e/ltc3539e-2 is guaranteed to meet performance specifications from 0c to 85c. specifications over C40c to 85c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: specification is guaranteed by design and not 100% tested in production. parameter conditions min typ max units maximum duty cycle v fb = 1.15v l 87 90 % minimum duty cycle v fb = 1.3v l 0 % switching frequency ltc3539 ltc3539-2 l l 0.7 1.8 1 2 1.3 2.4 mhz mhz mode input high v oltage 0.88 v mode input low voltage 0.3 v mode input current v mode = 1.2v 0.3 1 a shdn input high voltage 0.88 v shdn input low voltage 0.3 v shdn input current v shdn = 1.2v v shdn = 3.3v 0.3 1 1 2 a a the l denotes the specifications which apply over the specified temperature range of C40c to 85c, otherwise specifications are at t a = 25c. v in = 1.2v, v out = 3.3v, unless otherwise noted. note 4: current measurements are made when the output is not switching. note 5: this ic includes overtemperature protection that is intended to protect the device during momentary overload conditions. junction temperature will exceed 125c when overtemperature protection is active. continuous operation above the specified maximum operating junction temperature may result in device degradation or failure. note 6: failure to solder the exposed backside of the package to the pc board ground plane will result in a thermal resistance much higher than 64c/w. typical performance characteristics efficiency vs load current and v in , v out = 1.8v efficiency vs load current and v in , v out = 3.3v load current (ma) efficiency (%) 100 10 90 70 50 30 80 60 40 20 0 power loss (mw) 1000 100 10 1 0.1 0.01 3539 g01 v in = 1v v in = 1.2v v in = 1.5v power loss efficiency 0.1 100 1000 10 1 load current (ma) efficiency (%) 100 10 90 70 50 30 80 60 40 20 0 3539 g02 v in = 1.2v v in = 1.8v v in = 3v power loss efficiency 0.1 100 1000 10 1 0.1 1 10 100 1000 power loss (mw) (t a = 25c unless otherwise noted) ltc 3539/ ltc 3539-2 35392fc
4 for more information www.linear.com/3539/3539-2 0.7 1.5 2.3 1.1 1.9 3.1 5.1 3.9 4.3 4.7 2.7 3.5 v in (v) i out (ma) 2000 200 1800 1400 1000 600 1600 1200 800 400 0 3539 g05 v out = 1.8v v out = 2.5v v out = 3.3v v out = 5v l = 2.2h v in (v) input current (a) 200 20 180 140 100 60 160 120 80 40 0 3539 g04 v out = 1.8v v out = 2.5v v out = 3.3v v out = 5v 0 2 4 1 3 5 typical performance characteristics efficiency vs load current and v in , v out = 5v no load input current vs v in maximum output current vs v in 0.1 1 10 100 1000 power loss (mw) load current (ma) efficiency (%) 100 10 90 70 50 30 80 60 40 20 0 3539 g03 v in = 2.4v v in = 3.6v v in = 4.2v power loss efficiency 0.1 100 1000 10 1 minimum load resistance during start-up vs v in burst mode threshold current vs v in ; v out = 1.8v 0.65 0.85 1.05 0.75 0.95 1.15 v in (v) load resistance () 3539 g06 10000 1000 100 10 0.1 v out = 3.3v (t a = 25c unless otherwise noted) normalized current limit vs v out v out (v) normalized current limit (a) 1.10 1.05 0.95 0.85 1.00 0.90 0.80 3539 g08 1.0 1.5 2.52.0 3.5 5.0 4.5 3.0 4.0 0.7 0.8 0.9 1 1.1 1.2 1.3 1.51.4 v in (v) load current (ma) 50 5 45 35 25 15 40 30 20 10 0 3539 g07a c out = 44f f sw = 1mhz f sw = 2mhz enter burst leave burst 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 v in (v) load current (ma) 50 5 45 35 25 15 40 30 20 10 0 3539 g07b c out = 44f f sw = 1mhz f sw = 2mhz enter burst leave burst 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.7 2.3 2.5 2.1 v in (v) load current (ma) 10 50 30 60 40 20 0 3539 g07c c out = 44f f sw = 1mhz f sw = 2mhz enter burst leave burst 0.7 1.1 1.5 1.9 2.3 2.7 3.1 4.33.93.5 v in (v) load current (ma) 100 10 90 70 50 30 80 60 40 20 0 3539 g07d c out = 44f f sw = 1mhz f sw = 2mhz enter burst leave burst burst mode threshold current vs v in ; v out = 2.5v burst mode threshold current vs v in ; v out = 3.3v burst mode threshold current vs v in ; v out = 5v ltc 3539/ ltc 3539-2 35392fc
5 for more information www.linear.com/3539/3539-2 temperature (c) v in (v) 0.80 0.75 0.65 0.55 0.70 0.60 0.50 3539 g12 1ma load no load ?50 0?25 50 100 25 75 temperature (c) change in v fb (%) 0.50 0.25 ?0.25 ?0.75 0 ?0.50 ?1.00 3539 g11 ?60 ?20?40 40 10080 200 60 v out (v) r ds(on) () 0.30 0.25 0.15 0.05 0.20 0.10 0 3539 g09 nmos pmos 1.5 2.52.0 3.5 5.55.04.5 3.0 4.0 temperature (c) normalized r ds(on) () 1.3 1.2 1.0 0.8 1.1 0.9 0.7 3539 g10 ?50 ?10?30 30 9070 10 50 typical performance characteristics r ds(on) vs v out r ds(on) change vs temperature v fb vs temperature start-up voltage vs temperature fixed frequency sw and i l(ac) burst mode sw and i l(ac) load step, fixed frequency load step, burst mode operation 500ns/div v in = 2.4v v out = 3.3v at 400ma c out = 22f v out 20mv/div ac-coupled inductor current 500ma/div sw pin 2v/div 3539 g13 500s/div v in = 2.4v v out = 3.3v c out = 22f i load = 100ma to 250ma step v out 50mv/div ac-coupled load current 200ma/div 3539 g15 5s/div v in = 3.3v v out = 5v c out = 22f v out 20mv/div ac-coupled inductor current 200ma/div sw pin 5v/div 3539 g14 500s/div v in = 2.4v v out = 3.3v c out = 22f i load = 20ma to 170ma v out 50mv/div ac-coupled load current 200ma/div 3539 g16 ltc 3539/ ltc 3539-2 35392fc
6 for more information www.linear.com/3539/3539-2 block diagram pin functions sw (pin 1): switch pin. connect inductor between sw and v in . keep pcb trace lengths as short and wide as pos- sible to reduce emi. if the inductor current falls to zero, or shdn is low, an internal anti-ring resistor is connected from sw to v in to minimize emi. pgnd (pin 2), gnd (pin 3): signal and power ground. provide a short direct pcb path between pgnd, gnd and the (C) side of the input and output capacitors. v in (pin 4): battery input voltage. connect a minimum of 2.2 f ceramic decoupling capacitor from this pin to ground. shdn (pin 5): logic controlled shutdown input. there is an internal 4m pull-down on this pin. shdn = high: normal operation. shdn = low: shutdown, quiescent current <1a. fb (pin 6): feedback input to the g m error amplifier. connect resistor divider tap to this pin. the output volt- age can be adjusted from 1.5 v to 5.25 v by: v out = 1.20v ? [1 + (r2/r1)] mode (pin 7): burst mode pin. a logic controlled input to select either automatic burst mode operation or forced fixed frequency operation. mode = high: burst mode operation at light loads mode = low: fixed frequency pwm mode v out (pin 8): output voltage sense and drain of the internal synchronous rectifier. pcb trace length from v out to the output filter capacitor should be as short and wide as possible. exposed pad (pin 9): the exposed pad must be soldered to the pcb ground plane. it serves as another ground connection, and as a means of conducting heat away from the die. ? + ? + 3539 bd sw shdn v out v out exposed pad wake burst i zero soft-start error amplifier/sleep comparator i pk comparator i zero comparator slope comparator i pk gnd v in v in mode fb fb r2 + ? logic and burst mode control gate drivers and anti-cross conduction thermal shutdown start-up clamp shutdown shutdown v best v out v b v sel uvlo uvlo tsd v ref v ref v ref well switch r1 1mhz/2mhz osc clk burst pwm onoff 1 4 8 6 3 pgnd 2 9 7 5 ltc 3539/ ltc 3539-2 35392fc
7 for more information www.linear.com/3539/3539-2 operation detailed description the ltc3539 is a high power synchronous boost converter in an 8-lead 2 mm 3 mm dfn package. with the ability to start up and operate from inputs of 700 mv, the device features fixed frequency, current mode pwm control for exceptional line and load regulation. the current mode architecture with adaptive slope compensation provides excellent transient load response, requiring minimal output filtering. internal soft- start and internal loop compensation simplifies the design process while minimizing the number of external components. the switching frequency of the ltc3539 is nominally 1 mhz, while the ltc3539-2 switches at 2 mhz. operation of the ltc3539 and ltc3539-2 is identical in all other respects. with its low r ds( on) and low gate charge internal n- channel mosfet switch and p-channel mosfet synchronous rectifier, the ltc3539 achieves high efficiency over a wide range of load current. burst mode operation maintains high efficiency at very light loads, reducing the quiescent current to just 10a. converter operation can be best understood by referring to the block diagram. low voltage start-up the ltc3539 includes an independent start-up oscillator designed to start up at an input voltage of 0.7 v (typical). soft-start and inrush current limiting are provided during start-up, as well as normal mode. when either v in or v out exceeds 1.4 v typical, the ic enters normal operating mode. once the output voltage exceeds the input by 0.24v , the ic powers itself from v out instead of v in . at this point the internal circuitry has no dependency on the v in input voltage, eliminating the requirement for a large input capacitor. the input voltage can drop as low as 0.5v . the limiting factor for the appli - cation becomes the ability of the power source to supply sufficient energy to the output at the low voltages, and the maximum duty cycle, which is clamped at 90% typical. note that at low input voltages, small voltage drops due to series resistance become critical, and greatly limit the power delivery capability of the converter. low noise fixed frequency operation soft - start : the ltc3539 / ltc3539-2 contains internal circuitry to provide soft- start operation. the internal soft-start circuitry ramps the peak inductor current from zero to its peak value of 2.6a ( typical) in approximately 0.5ms, allowing start-up into heavy loads. the soft-start circuitry is reset in the event of a thermal shutdown or shutdown command. oscillator : an internal oscillator sets the switching fre- quency to 1 mhz for the ltc3539, and 2 mhz for the ltc3539-2. shutdown: the part is shutdown by pulling the shdn pin below 0.3 v, and activated by pulling the shdn pin above 0.88 v. note that shdn can be driven above v in or v out , as long as it is limited to less than the absolute maximum rating. error amplifier: the error amplifier is a transconductance type. the non-inverting input is internally connected to the 1.2 v reference and the inverting input is connected to fb. clamps limit the minimum and maximum error amp output voltage for improved large signal transient response. power converter control loop compensation is provided internally. a voltage divider from v out to ground programs the output voltage via fb from 1.5 v to 5.25 v. v out = 1.2v ? [1 + (r2/r1)]. current sensing: lossless current sensing converts the peak current signal of the n-channel mosfet switch into a voltage which is summed with the internal slope compensation. the summed signal is compared to the error amplifier output to provide a peak current control command for the pwm . current limit: the current limit comparator shuts off the n -channel mosfet switch once its threshold is reached. peak switch current is limited to approximately 2.6 a, independent of input or output voltage, unless v out falls below 0.7v, in which case the current limit is cut in half. ltc 3539/ ltc 3539-2 35392fc
8 for more information www.linear.com/3539/3539-2 operation zero current comparator: the zero current comparator monitors the inductor current to the output and shuts off the synchronous rectifier once this current reduces to ap - proximately 40 ma. this prevents the inductor current from reversing in polarity, improving efficiency at light loads. synchronous rectifier: the p-channel mosfet synchro - nous rectifier is disabled when v out is much less than v in . this is to control inrush current and to prevent inductor current from running away anti-ringing control: the anti-ringing control connects a resistor across the inductor to prevent high frequency ringing on the sw pin during discontinuous current mode operation. the ringing of the resonant circuit formed by l and c sw ( capacitance on sw pin) is low energy, but can cause emi radiation. output disconnect: the ltc3539 is designed to allow true output disconnect by eliminating body diode conduction of the internal p-channel mosfet rectifier. this allows v out to go to zero volts during shutdown, drawing no current from the input source. it also provides inrush current limiting at turn-on, minimizing surge currents seen by the input supply. note that to obtain the advantages of output disconnect, there must not be an external schottky diode connected between the sw pin and v out . the output disconnect feature also allows v out to be pulled high, without any reverse current into a battery on v in . thermal shutdown: if the die temperature exceeds 160c, the device will go into thermal shutdown. all switches will be turned off and the internal soft-start capacitor will be discharged. the device will be enabled again when the die temperature drops by about 15c. burst mode operation when burst mode operation is enabled by bringing the mode pin above 0.88 v, the ltc3539 will automatically enter burst mode operation at light load current, then return to fixed frequency pwm mode when the load in - creases. refer to the typical performance characteristics to see the output load burst mode threshold vs v in . the load current at which burst mode operation is entered can be changed by adjusting the inductor value. raising the inductor value will lower the load current at which burst mode operation is entered. in burst mode operation, the ltc3539 still switches at a fixed frequency, using the same error amplifier and loop compensation for peak current mode control. this control method eliminates any output transient when switching between modes. in burst mode operation, energy is deliv- ered to the output until it reaches the nominal regulation value, then the ltc3539 transitions to sleep mode where the outputs are off and the ltc3539 consumes only 10a of quiescent current from v out . when the output voltage droops slightly, switching resumes. this maximizes ef- ficiency at very light loads by minimizing switching and qu iescent current losses. burst mode output voltage ripple, which is application sensitive and typically 1% to 2% peak-to-peak if data sheet recommendations are fol - lowed, can be reduced by using more output capacitance (47f or greater). as the load increases, the ltc3539 will automatically leave burst mode operation. once the ltc3539 has left burst mode operation and returned to normal operation, it will remain there until the output load is reduced below the burst threshold. burst mode operation is inhibited during start-up until soft-start is complete and v out is at least 0.24 v greater than v in . when the mode pin is below 0.3 v, the ltc3539 features continuous pwm operation. in this mode, at very light loads, the ltc3539 will exhibit pulse-skip operation. if the mode pin voltage exceeds the greater of v in or v out by 0.5v, the mode pin will sink additional current. due to the high inductor current slew rate in 5 v output applications, the ltc3539-2 may not enter burst mode operation for input voltages less than 1.8 v. for 5 v applica - tions requiring burst mode operation, the 1 mhz ltc3539 is recommended. refer to the typical performance characteristics curves for the burst mode thresholds for different input and output voltages. ltc 3539/ ltc 3539-2 35392fc
9 for more information www.linear.com/3539/3539-2 applications information v in > v out operation the ltc3539 will maintain output voltage regulation even when the input voltage is above the desired output. note that the efficiency and the maximum output current capability are reduced. refer to typical performance characteristics. short-circuit protection the ltc3539 output disconnect feature allows an output short circuit while maintaining a maximum internally set current limit. to reduce power dissipation under short- circuit conditions, the peak switch current limit is reduced to 1.4a (typical). schottky diode although it is not required, adding a schottky diode from sw to v out will improve efficiency by about 2%. note that this defeats the output disconnect, v in > v out operation and short circuit protection features. pcb layout guidelines the high speed operation of the ltc3539 demands careful attention to board layout. a careless layout will result in reduced performance. figure 1 shows the recommended component placement. a large ground pin copper area will help to lower the die temperature. a multilayer board with a separate ground plane is ideal. component selection inductor selection the ltc3539 can utilize small surface mount and chip inductors due to the high switching frequency. inductor values between 3.3 h and 4.7 h for the ltc3539 and between 1.5h and 2.5 h for the ltc3539-2 are suitable for most applications.* larger values of inductance will allow slightly greater output current capability ( and lower the burst mode threshold) by reducing the inductor ripple current. however, increasing the inductance above 10h will increase size while providing little improvement in output current capability. the minimum inductance value is given by: l > v in(min) ? (v out(max) ? v in(min) ) ripple ? v out(max) ? f where: f = 1 for the ltc3539 or 2 for the ltc3539-2 ripple = allowable inductor current ripple (amps peak -to-peak) v in(min) = minimum input voltage v out(max) = maximum output voltage the inductor current ripple is typically set for 20% to 40% of the maximum inductor current. high frequency ferrite core inductor materials improve efficiency by reducing frequency dependent power losses compared to cheaper powdered iron types. the inductor should have low esr (series resistance of the windings) to reduce the i 2 r power losses, and must accommodate the peak inductor current without saturating. molded chokes and some chip induc - tors usually do not have enough core area to support the peak inductor current of 2.6 a seen on the ltc3539. to minimize radiated noise, use a shielded inductor. see table 1 for suggested suppliers and representative components. figure 1. recommended component placement for single layer board *single cell applications (v in < 1.6v) should use a 2.2h inductor for the lt c 3539 + sw ltc3539 1 gnd minimize trace on fb and sw 3 pgnd 2 v in multiple vias to ground plane v in v out fb shdn 3539 f01 4 8 6 mode 7 5 ltc 3539/ ltc 3539-2 35392fc
10 for more information www.linear.com/3539/3539-2 applications information table 1. representative inductors vendor part /style coilcraft (847) 639-6400 www.coilcraft.com mss 5131 lps4018-222 mss6132 mos6020 murata www.murata.com lqh 55d lqh66s sumida (847) 956-0666 www.sumida.com cdrh 4d22 cdrh4d28c cdrh5d28 cdr6d23 tdk (847) 803-6100 www.component.tdk.com vlf 5014st t oko (408) 432-8282 www.tokoam.com d 53lc d63lcb w rth (201) 785-8800 www.we-online.com we -tpc t ype lh, x we-pd type xs output and input capacitor selection the internal loop compensation of the ltc3539 is designed to be stable with output capacitor values of 22 f or greater. although ceramic capacitors are recommended, low esr (equivalent series resistance) tantalum capacitors may be used as well. low esr capacitors should be used to minimize the output voltage ripple. multilayer ceramic capacitors are an excellent choice as they have extremely low esr and are available in small footprints. a 22 f to 47 f output capacitor is sufficient for output voltages of 3 v or greater. an output capacitor of up to 100 f is required at lower output voltages. even with v out greater than 3 v, larger values up to 100 f may be used to obtain extremely low output voltage ripple and improve transient response. x5r and x7r dielectric materials are preferred for their ability to maintain capacitance over wide voltage and temperature ranges. y5v types should not be used. a small ceramic capacitor in parallel with a larger tantalum capacitor may be used in demanding applications which have large load transients. a feedforward capacitor across the top resistor of the feedback divider ( from v out to fb) is usually required to improve transient response. a typical value of 33pf will generally suffice. low esr input capacitors reduce input switching noise and reduce the peak current drawn from the battery. it follows that ceramic capacitors are also a good choice for input decoupling and should be located as close as possible to the device. a 2.2 f input capacitor is sufficient for most applications. larger values may be used without limitations. table 2 shows a list of several ceramic capaci - tor manufacturers . consult the manufacturers directly for detailed information on their selection of ceramic parts. table 2. capacitor vendor information supplier phone website avx (803) 448-9411 www.avxcorp.com murata (714) 852-2001 www.murata.com taiyo-yuden (408) 573-4150 www.t-yuden.com tdk (847) 803-6100 www.component.tdk.com ltc 3539/ ltc 3539-2 35392fc
11 for more information www.linear.com/3539/3539-2 typical applications 1 cell to 1.8v 1 cell to 3.3v li-ion cell to 5v 3539 ta02 ltc3539 v in sw 2.2f v out 1.8v 500ma v in 1v to 1.6v 2.2h v out mode shdn fb pgnd gnd 1.91m 1m 22f* 2 *at high load currents, a tantalum capacitor will improve performance. 33pf burst pwm onoff 3539 ta03 ltc3539 v in sw 2.2f v out 3.3v 350ma v in 0.9v to 1.6v 2.2h v out mode shdn fb pgnd gnd 562k 1m 22f 2 burst pwm onoff 33pf 3539 ta04 ltc3539-2 v in sw 2.2f v out 5v 750ma v in 3v to 4.5v 2.2h v out mode shdn fb pgnd gnd 309k 1m 22f 2 burst pwm onoff 33pf ltc 3539/ ltc 3539-2 35392fc
12 for more information www.linear.com/3539/3539-2 3.00 0.10 (2 sides) 2.00 0.10 (2 sides) note: 1. drawing is not a jedec package outline 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.40 0.10 bottom view?exposed pad 0.75 0.05 r = 0.115 typ r = 0.05 typ 1.35 ref 1 4 8 5 pin 1 bar top mark (see note 6) 0.200 ref 0.00 ? 0.05 (dcb8) dfn 0106 rev a 0.23 0.05 0.45 bsc pin 1 notch r = 0.20 or 0.25 45 chamfer 0.25 0.05 1.35 ref recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 2.10 0.05 0.70 0.05 3.50 0.05 package outline 0.45 bsc 1.35 0.10 1.35 0.05 1.65 0.10 1.65 0.05 dcb package 8-lead plastic dfn (2mm 3mm) (reference ltc dwg # 05-08-1718 rev a) package description please refer to http://www .linear.com/designtools/packaging/ for the most recent package drawings. ltc 3539/ ltc 3539-2 35392fc
13 for more information www.linear.com/3539/3539-2 information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. revision history rev date description page number b 02/13 improved feedback voltage tolerance spec 1, 2 clarified burst mode operation 8 c 09/14 corrected block diagram schematic 6 (revision history begins at rev b) ltc 3539/ ltc 3539-2 35392fc
14 for more information www.linear.com/3539/3539-2 ? linear technology corporation 2008 lt 0914 rev c ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/3539/3539-2 related parts part number description comments ltc3400/ ltc3400b 600ma i sw , 1.2mhz, synchronous step-up dc/dc converters 92% efficiency v in : 0.85v to 5v, v out(max) = 5v, i q = 19a/300a, i sd <1a, thinsot? package ltc3401 1a i sw , 3mhz, synchronous step-up dc/dc converter 97% efficiency v in : 0.5v to 5v, v out(max) = 6v, i q = 38a, i sd <1a, 10-lead ms package ltc3402 2a i sw , 3mhz, synchronous step-up dc/dc converter 97% efficiency v in : 0.5v to 5v, v out(max) = 6v, i q = 38a, i sd <1a, 10-lead ms package ltc3421 3a i sw , 3mhz, synchronous step-up dc/dc converter with output disconnect 95% efficiency v in : 0.5v to 4.5v, v out(max) = 5.25v, i q = 12a, i sd <1a, qfn24 package ltc3422 1.5a i sw , 3mhz synchronous step-up dc/dc converter with output disconnect 95% efficiency v in : 0.5v to 4.5v, v out(max) = 5.25v, i q = 25a, i sd <1a, 3mm 3mm dfn package ltc 3423 / ltc3424 1a/2a i sw , 3mhz, synchronous step-up dc/dc converter 95% efficiency v in : 0.5v to 5.5v, v out(max) = 5.5v, i q = 38a, i sd <1a, 10-lead ms package ltc 3426 2a i sw , 1.2mhz, step-up dc/dc converter 92% efficiency v in : 1.6v to 4.3v, v out(max) = 5v, i sd <1a, sot-23 package ltc3428 500ma i sw , 1.25mhz/2.5mhz, synchronous step-up dc/dc converters with output disconnect 92% efficiency v in : 1.8v to 5v, v out(max) = 5.25v, i sd <1a, 3mm 3mm dfn package ltc 3429 600ma i sw , 500khz, synchronous step-up dc/dc converter with output disconnect and soft-start 96% efficiency v in : 0.5v to 4.4v, v out(max) = 5v, i q = 20a/300a, ltc3458 1.4a i sw , 1.5mhz, synchronous step-up dc/dc converter/output disconnect/burst mode operation 93% efficiency v in : 1.5v to 6v, v out(max) = 7.5v, i q = 15a, i sd <1a, dfn12 package ltc 3458l 1.7a i sw , 1.5mhz, synchronous step-up dc/dc converter with output disconnect, automatic burst mode operation 94% efficiency v out(max) = 6v, i q = 12a, dfn12 package ltc3459 70ma i sw , 10v micropower synchronous boost converter/output disconnect/burst mode operation v in : 1.5v to 5.5v, v out(max) = 10v, i q = 10a, i sd <1a, thinsot package ltc3525-3/ ltc3525-3.3/ ltc3525-5 400ma micropower synchronous step-up dc/dc converter with output disconnect 95% efficiency v in : 1v to 4.5v, v out(max) = 3.3v or 5v, i q = 7a, i sd <1a, sc-70 package ltc3525l-3 400ma micropower synchronous step-up dc/dc converter with output disconnect 95% efficiency v in : 0.88v to 4.5v, v out(max) = 3v, i q = 7a, i sd <1a, sc-70 package ltc 3526 / ltc3526b 500ma, 1mhz synchronous step-up dc/dc converter with output disconnect 94% efficiency v in : 0.85v to 5v, v out(max) = 5.25v, i q = 9a, i sd <1a, 2mm 2mm dfn-6 package ltc 3526l 550ma, 1mhz synchronous step-up dc/dc converter with output disconnect 94% efficiency v in : 0.68v to 5v, v out(max) = 5.25v, i q = 9a, i sd <1a, 2mm 2mm dfn-6 package ltc 3527 / ltc3527-1 dual 800ma/400ma, 1.2mhz/2.2mhz synchronous step-up dc/dc converter with output disconnect 94% efficiency v in : 0.68v to 5v, v out(max) = 5.25v, i q = 12a, i sd <1a, 3mm 3mm qfn-16 package ltc 3528 / ltc3528b 1a, 1mhz synchronous step-up dc/dc converter with output disconnect 94% efficiency v in : 0.68v to 5v, v out(max) = 5.25v, i q = 12a, i sd <1a, 2mm 3mm dfn-8 package ltc 3539/ ltc 3539-2 35392fc

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