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ltc3528-2 1 35282fa typical application features applications description 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn the ltc ? 3528-2 is a synchronous, fxed frequency step-up dc/dc converter with output disconnect. high effciency synchronous rectifcation, in addition to a 700mv start- up voltage and operation down to 500mv once started, provides longer run-time for single or multiple cell battery- powered products. a switching frequency of 2mhz minimizes solution footprint by allowing the use of tiny, low profle induc - tors and ceramic capacitors. the current mode pwm is internally compensated, simplifying the design process. the ltc3528-2 enters burst mode operation at light loads. anti-ringing circuitry reduces emi by damping the induc - tor in discontinuous mode. additional features include a low shutdown current, open-drain power good output, short-circuit protection and thermal overload protection. the ltc3528-2 is offered in an 8-lead 2mm 3mm 0.75mm dfn package. n delivers 3.3v at 200ma from a single alkaline/ nimh cell or 3.3v at 400ma from two cells n v in start-up voltage: 700mv n 0.50v to 5.5v input range n 1.6v to 5.25v v out range n up to 94% effciency n output disconnect n 2mhz fixed frequency operation n v in > v out operation n integrated soft-start n current mode control with internal compensation n burst mode ? operation with 12a quiescent current n internal synchronous rectifer n logic controlled shutdown: <1a n anti-ringing control n low profle (2mm 3mm 0.75mm) dfn package n medical instruments n noise canceling headphones n wireless mice n bluetooth headsets effciency and power loss load current (ma) 0.01 80 90 100 100 35282 ta01b 70 60 0.1 1 10 1000 50 40 30 20 10 0 100 1000 10 1 0.1 0.01 efficiency (%) power loss (mw) efficiency power loss v out = 3.3v v in = 2.4v sw v in 499k 2.2h 287k 4.7f 10f 68pf 35282 ta01a ltc3528-2 shdn pgood v out fb v in 1.8v to 3.2v v out 3.3v 400ma off on gnd l , lt, ltc, ltm, burst mode, linear technology and the linear logo are registered trademarks and thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners.
ltc3528-2 2 35282f electrical characteristics absolute maximum ratings v in voltage ................................................... C0.3v to 6v sw voltage dc ............................................................ C0.3v to 6v pulsed < 100ns ........................................ C0.3v to 7v shdn , fb voltage ........................................ C0.3v to 6v v out ............................................................. C0.3v to 6v pgood ......................................................... C0.3v to 6v operating junction temperature range (notes 2, 5) ............................................ C40c to 125c junction temperature ........................................... 125c storage temperature range ................... C65c to 125c (note 1) parameter conditions min typ max units v in range operating, excluding start-up l 0.5 5.5 v minimum start-up voltage i load = 1ma l 0.70 0.88 v output voltage adjust range t a = 0c to 85c l 1.7 1.6 5.25 5.25 v v feedback voltage (note 7) l 1.170 1.200 1.230 v feedback input current v fb = 1.3v 1 50 na quiescent currentshutdown v shdn = 0v, not including switch leakage, v out = 0v 0.01 1 a quiescent currentactive measured on v out , nonswitching (note 4) 300 500 a quiescent currentburst measured on v out , fb > 1.230v 12 20 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 10 a n-channel mosfet switch on resistance 0.175 p-channel mosfet switch on resistance 0.250 n-channel mosfet current limit l 1.0 1.5 a current limit delay time to output (note 3) 60 ns maximum duty cycle v fb = 1.15v l 87 92 % the l denotes the specifcations which apply over the specifed operating junction temperature range, otherwise specifcations are at t a = 25c (note 2). v in = 1.2v, v out = 3.3v, unless otherwise noted. top view 9 ddb package 8-lead (3mm 2mm) plastic dfn 5 6 7 8 4 3 2 1 shdn fb pgood v out v in sgnd pgnd sw t jmax = 125c, ja = 76c/w (note 6) exposed pad (pin 9) is gnd, must be soldered to pcb lead free finish tape and reel part marking package description temperature range ltc3528eddb-2#pbf ltc3528eddb-2#trpbf ldnz 8-lead (3mm 2mm) plastic dfn C40c to 125c consult ltc marketing for parts specifed with wider operating temperature ranges. consult ltc marketing for information on non-standard lead based fnish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifcations, go to: http://www.linear.com/tapeandreel/ pin configuration order information
ltc3528-2 3 35282fa 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 ltc3528-2 is tested under pulsed load conditions such that t j t a . the ltc3528e-2 is guaranteed to meet specifcations from 0c to 85c junction temperature. specifcations over C40c to 125c operating junction temperature range are assured by design, characterization and correlation with statistical process controls. note that the maximum ambient temperature consistent with these specifcations is determined by specifc operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors. the junction temperature (t j , in c) is calculated from the ambient temperature (t a , in c) and power dissipation (p d , in watts) according to the formula: t j = t a + (p d ? ja ) where ja = 76c/w is the package thermal impedance. parameter conditions min typ max units minimum duty cycle v fb = 1.3v l 0 % frequency l 1.8 2.0 2.4 mhz shdn input high voltage 0.88 v shdn input low voltage 0.25 v shdn input current v shdn = 1.2v 0.3 1 a pgood threshold percentage referenced to feedback voltage falling C7 C10 C13 % pgood low voltage i pgood = 1ma v out = 1.6v, i pgood = 1ma 0.05 0.05 0.1 0.2 v v pgood leakage current v pgood = 5.5v 0.01 1 a electrical characteristics the l denotes the specifcations which apply over the specifed operating junction temperature range, otherwise specifcations are at t a = 25c (note 2). v in = 1.2v, v out = 3.3v, unless otherwise noted. note 3: specifcation is guaranteed by design and not 100% tested in production. 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 specifed 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 76c/w. note 7: the ic is tested in a feedback loop to make the measurement. typical performance characteristics (t a = 25c unless otherwise noted) effciency vs load current and v in for v out = 1.8v effciency vs load current and v in for v out = 3v load current (ma) 0.01 efficiency (%) power loss (mw) 60 80 100 100 35282 g01 40 20 50 70 90 30 10 0 10 100 1000 1 0.1 0.01 0.1 1 10 1000 v in = 1v v in = 1.2v v in = 1.5v efficiency power loss load current (ma) 0.01 efficiency (%) power loss (mw) 60 80 100 100 35282 g26 40 20 50 70 90 30 10 0 10 100 1000 1 0.1 0.01 0.1 1 10 1000 v in = 1v v in = 1.5v v in = 2.4v efficiency power loss
ltc3528-2 4 35282f maximum output current vs v in minimum load resistance during start-up vs v in start-up delay time vs v in effciency vs load current and v in for v out = 5v effciency vs load current and v in for v out = 3.3v v in (v) 1 i out (ma) 700 2.5 35282 g05 400 200 1.5 2 3 100 0 800 600 500 300 3.5 4 4.5 v out = 1.8v v out = 3.3v v out = 5v v in (v) 0.7 10 r load () 1000 100 10000 0.8 0.9 1 35282 g06 v in (v) 1 delay (s) 120 2.5 35282 g07 90 70 1.5 2 3 60 50 130 110 100 80 3.5 4 4.5 typical performance characteristics (t a = 25c unless otherwise noted) load current (ma) 0.01 80 90 100 100 35282 g02 70 60 0.1 1 10 1000 50 40 30 100 1000 10 1 0.1 0.01 efficiency (%) power loss (mw) v in = 1.2v v in = 1.8v v in = 2.4v v in = 3v efficiency power loss load current (ma) 0.01 80 90 100 100 35282 g03 70 60 0.1 1 10 1000 50 40 30 100 1000 10 1 0.1 efficiency (%) power loss (mw) v in = 1.2v v in = 2.4v v in = 3.6v v in = 4.2v efficiency power loss v in (v) 1 10 i in (a) 30 50 70 90 110 130 2 3 4 5 35282 g04 v out = 1.8v v out = 3v v out = 3.3v v out = 5v no-load input current vs v in burst mode threshold current vs v in burst mode threshold current vs v in burst mode threshold current vs v in v in (v) 1 i out (ma) 40 60 1.4 35282 g08 20 0 1.1 1.2 1.3 1.5 80 v out = 1.8v enter burst exit burst v in (v) 1 i out (ma) 40 60 35282 g09 20 0 1.5 2 2.5 80 v out = 3v enter burst exit burst v in (v) 1 i out (ma) 40 60 3 35282 g10 20 0 1.5 2 2.5 80 v out = 3.3v enter burst exit burst
ltc3528-2 5 35282fa oscillator frequency change vs v out r ds(on) vs v out oscillator frequency change vs temperature r ds(on) change vs temperature v fb vs temperature start-up voltage vs temperature typical performance characteristics (t a = 25c unless otherwise noted) burst mode threshold current vs v in v in (v) 1 0 i out (ma) 20 40 60 80 1.5 2 2.5 3 35242 g11 3.5 4 v out = 5v enter burst exit burst v out (v) 1.5 frequency change (%) ?1.50 0 0.25 0.50 2.5 3.5 4 35282 g12 ?2.00 ?0.50 ?1.00 ?1.75 ?0.25 ?2.25 ?0.75 ?1.25 2 3 4.5 5 v out (v) 1.5 300 350 450 3 4 35282 g13 250 200 2 2.5 3.5 4.5 5 150 100 400 r ds(on) (m) pmos nmos temperature (?c) ?50 frequency change (%) 0 1 2 25 75 35282 g14 ?1 ?2 ?25 0 50 100 125 ?3 ?4 temperature (c) ?50 1.196 v fb (v) 1.197 1.198 1.199 1.200 ?25 0 25 50 35282 g16 75 100 125 temperature (c) ?50 ?25 600 start-up voltage (mv) 700 850 0 50 75 35282 g17 650 800 750 25 100 125 output voltage vs load current for v out = 5v load current (ma) 0 change in output voltage (%) ?0.05 0 0.05 3528-2 g27 ?0.10 ?0.15 ?0.20 200 400 0.10 0.15 0.20 v in = 3.6v 600 output voltage vs load current for v out = 3.3v load current (ma) 0 change in output voltage (%) ?0.05 0 0.05 35282 g28 ?0.10 ?0.15 ?0.20 100 50 150 0.10 0.15 0.20 v in = 1.2v 200 temperature (?c) ?50 change (%) 20 30 40 25 75 35282 g15 10 0 ?25 0 50 100 125 ?10 ?20
ltc3528-2 6 35282f load step response (burst mode operation, 3.6v to 5v) v out and i in during soft-start typical performance characteristics (t a = 25c unless otherwise noted) v out 1v/div shdn pin 200s/div 35282 g21 v in = 1.2v v out = 3.3v c out = 10f l = 2.2h i in 200ma/div v out 100mv/div 20s/div 35282 g23 v in = 3.6v v out = 5v c out = 10f l = 2.2h load current = 20ma to 550ma load current 200ma/div load step response (fixed frequency, 1.2v to 3.3v) load step response (burst mode operation, 1.2v to 3.3v) v out 100mv/div 20s/div 35282 g24 v in = 1.2v v out = 3.3v c out = 10f l = 2.2h load current = 20ma to 170ma load current 100ma/div v out 100mv/div 20s/div 35282 g25 v in = 1.2v v out = 3.3v c out = 10f l = 2.2h load current = 10ma to 160ma load current 100ma/div load step response (fixed frequency, 3.6v to 5v) v out 100mv/div 20s/div 35282 g22 v in = 3.6v v out = 5v c out = 10f l = 2.2h load current = 100ma to 550ma load current 200ma/div fixed frequency v out ripple and inductor current waveforms v out 20mv/div 500ns/div 35282 g19 v in = 1.2v v out = 3.3v c out = 10f c ff = 33pf i out = 100ma l = 2.2h i l 200ma/div burst mode waveforms 5s/div 35282 g20 v in = 3.6v v out = 5v c out = 10f c ff = 33pf i load = 30ma v out 50mv/div inductor current 100ma/div
ltc3528-2 7 35282fa pin functions shdn (pin 1): logic controlled shutdown input. there is an internal 4m pull-down resistor on this pin. ? shdn = high: normal operation ? shdn = low: shutdown, quiescent current < 1a fb (pin 2): feedback input. connect resistor divider tap to this pin. the output voltage can be adjusted from 1.6v to 5.25v by: v out = 1.20v ? 1 + r2 r1 ? ? ? ? ? ? pgood (pin 3): power good comparator output. this open-drain output is low when v fb < 10% from its regu - lation voltage. v out (pin 4): output voltage sense and drain connection of the internal synchronous rectifer. pcb trace length from v out to the output flter capacitor (4.7f minimum) should be as short and wide as possible. sw (pin 5): switch pin. connect inductor between sw and v in . keep pcb trace lengths as short and wide as possible to reduce emi. if the inductor current falls to zero, or shdn is low, an internal anti-ringing switch is connected from sw to v in to minimize emi. pgnd (pin 6): power ground. provide a short direct pcb path between pgnd and the (C) side of the input and output capacitors. sgnd (pin 7): signal ground. provide a short direct pcb path between sgnd and the (C) side of the input and output capacitors. v in (pin 8): battery input voltage. connect a minimum of 1f ceramic decoupling capacitor from this pin to ground. gnd (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.
ltc3528-2 8 35282f block diagram 8 + ? + ? gate drivers and anti-cross conduction logic clk uvlo pk pk comp slope comp i zero comp error amp sleep comp i zero wake exposed pad + ? well switch mode control uvlo v ref v ref 4m shdn v best start-up 2mhz osc tsd thermal shutdown shutdown anti-ring v sel v in 5 4 sw v out l1 2.2h v b shutdown clamp burst soft-start v ref + ? v ref ? 10% fb fb v out 2 9 sgnd 35282 bd 7 pgnd 6 fb r2 c out 10f v out 1.6v to 5.25v r1 1 pgood 3 c in 4.7f v in 0.7v to 5v
ltc3528-2 9 35282fa operation the ltc3528-2 is a 2mhz synchronous boost converter housed in an 8-lead 3mm 2mm dfn package. with the ability to start up and operate from inputs less than 0.88v, the device features fxed frequency, current mode pwm control for exceptional line and load regulation. the cur - rent mode architecture with adaptive slope compensation provides excellent transient load response and requires minimal output fltering. internal soft-start and internal loop compensation simplifes the design process while minimizing the number of external components. with its low r ds(on) and low gate charge internal n-channel mosfet switch and p-channel mosfet synchronous recti - fer, the ltc3528-2 achieves high effciency over a wide range of load current. the ltc3528-2 features continuous 2mhz pwm operation over a wide range of load current. at very light loads, the ltc3528 - 2 will enter burst mode operation to maintain high effciency. operation can be best understood by referring to the block diagram. low voltage start-up the ltc3528-2 includes an independent start-up oscillator designed to operate at an input voltage of 0.70v (typical). soft-start and inrush current limiting are provided during start-up, as well as normal operating mode. when either v in or v out exceeds 1.6v 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 application becomes the availability of the power source to supply suffcient power to the output at the low voltages, and the maximum duty cycle, which is clamped at 92% 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 ltc3528-2 contains internal circuitry to provide soft- start operation. the internal soft-start circuitry slowly ramps the peak inductor current from zero to its peak value of 1.5a (typical), allowing start-up into heavy loads. the soft-start time is approximately 0.5ms. the soft-start circuitry is reset in the event of a commanded shutdown or a thermal shutdown. oscillator an internal oscillator sets the frequency of operation to 2mhz. shutdown the converter is shut down by pulling the shdn pin below 0.25v, and activated by pulling shdn above 0.88v. although shdn can be driven above v in or v out (up to the absolute maximum rating) without damage, the ltc3528-2 has a proprietary test mode that may be engaged if shdn is held in the range of 0.5v to 1v higher than the greater of v in or v out . if the test mode is engaged, normal pwm switching action is interrupted, which can cause undesirable opera- tion in some applications. therefore, in applications where shdn may be driven above v in , a resistor divider or other means must be employed to keep the shdn voltage below (v in + 0.4v) to prevent the possibility of the test mode being engaged. please refer to figure 1 for two possible implementations (refer to block diagram) 4m 30% shdn ltc3528-2 r 1m v cntrl v cntrl 4m 30% shdn ltc3528-2 zetex zc2811e r > (v cntrl /(v in + 0.4) ? 1) m v in 1m 3528 f01 figure 1. recommended shutdown circuits when driving shdn above v in
ltc3528-2 10 35282f error amplifer the error amplifer is a transconductance type. the nonin - verting input is internally connected to the 1.20v 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 1.6v to 5.25v. v out = 1.20v ? 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 amplifer 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. the cur - rent limit comparator delay to output is typically 60ns. peak switch current is limited to approximately 1.5a, independent of input or output voltage, unless v out falls below 0.7v, in which case the current limit is cut in half. zero current comparator the zero current comparator monitors the inductor cur - rent to the output and shuts off the synchronous rectifer when this current reduces to approximately 20ma. this prevents the inductor current from reversing in polarity, improving effciency at light loads. synchronous rectifer to control inrush current and to prevent the inductor current from running away when v out is close to v in , the p-channel mosfet synchronous rectifer is only enabled when v out > (v in + 0.24v). 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 ltc3528-2 is designed to allow true output discon - nect by eliminating body diode conduction of the internal p-channel mosfet rectifer. this allows for v out to go to zero volts during shutdown, drawing no current from the input source. it also enables inrush current limiting at turn- on, minimizing surge currents seen by the input supply. note that to obtain the advantages of output disconnect, a schottky diode cannot be connected between sw and v out . the output disconnect feature also allows v out to be forced above the programmed regulation voltage, without any reverse current into the input power source. thermal shutdown if the die temperature exceeds 160c, the ltc3528-2 enters thermal shutdown. all switches will be turned off and the soft-start capacitor will be discharged. the device will be enabled again when the die temperature drops by approximately 15c. burst mode operation the ltc3528-2 will automatically enter burst mode op - eration at light load current and return to fxed frequency pwm mode when the load increases. refer to the typical performance characteristics to see the output load burst mode threshold vs v in . the load 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 ltc3528-2 continues switch - ing at a fxed frequency of 2mhz, using the same error amplifer and loop compensation for peak current mode control. this control method minimizes output transients operation (refer to block diagram)
ltc3528-2 11 35282fa operation (refer to block diagram) when switching between modes. in burst mode opera- tion, energy is delivered to the output until it reaches the nominal regulated value, then the ltc3528-2 transitions to sleep mode where the outputs are off and the ltc3528C2 consumes only 12a of quiescent current from v out . once the output voltage has drooped slightly, switching resumes again. this maximizes effciency at very light loads by minimizing switching and quiescent current losses. burst mode output ripple, which is typically 1% peak-to-peak, can be reduced by using more output capacitance (10f or greater). as the load current increases, the ltc3528-2 automatically leaves burst mode operation. note that larger output ca - pacitor values may cause this transition to occur at lighter loads. the regulator will also leave burst mode operation if a load transient occurs which causes the inductor current to repeatedly reach current limit. once the ltc3528-2 has left burst mode operation and returned to normal opera- tion, it will remain there until the output load is reduced below the burst threshold. burst mode operation is inhibited during start-up and until soft-start is done and v out is at least 0.24v greater than v in . single cell to 5v step-up applications due to the high inductor current slew rate in applications boosting to 5v from a single cell (alkaline, nicd or nimh), the ltc3528-2 may not enter burst mode operation at in - put voltages below 1.5v. for single cell to 5v applications requiring burst mode operation, the 1mhz ltc3528 is recommended. refer to the typical performance charac - teristics for the burst mode thresholds for different input and output voltages.
ltc3528-2 12 35282f applications information v in > v out operation the ltc3528-2 maintains voltage regulation even when the input voltage is above the desired output voltage. note that the effciency is much lower in this mode, and the maximum output current capability will be less. refer to the typical performance characteristics. short-circuit protection the ltc3528-2 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 750ma (typical). schottky diode although not required, adding a schottky diode from sw to v out will improve effciency by about 2%. note that this defeats the output disconnect and short-circuit protection features. pcb layout guidelines the high speed operation of the ltc3528-2 demands careful attention to board layout. a careless layout will not produce the advertised performance. figure 2 shows the recommended component placement. a large ground copper area with the package backside metal pad properly soldered will help to lower the chip temperature. a multi - layer board with a separate ground plane is ideal, but not absolutely necessary. component selection inductor selection the ltc3528-2 can utilize small surface mount chip induc - tors due to its fast 2mhz switching frequency. inductor values between 1.5h and 3.3h are suitable for most applications. larger values of inductance will allow slightly greater output current capability by reducing the inductor ripple current. 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) C v in(min) ( ) 2 ? ripple ? v out(max) h where: ripple = allowable inductor current ripple (amps peak- 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 reduce frequency dependent power losses compared to cheaper powdered iron types, improving effciency. the inductor should have low esr (series resistance of the windings) to reduce the i 2 r power losses, and must be able to handle the peak inductor cur - rent without saturating. molded chokes and some chip inductors usually do not have enough core area to support the peak inductor currents of 1.5a seen on the ltc3528-2. to minimize radiated noise, use a shielded inductor. see table 1 for suggested components and suppliers. figure 2. recommended component placement for single layer board shdn fb pgood ltc3528-2 v out 35282 f02 c out v in v in c in sgnd pgnd sw multiple vias to ground plane 8 5 6 7 1 4 3 2 +
ltc3528-2 13 35282fa applications information table 1. recommended inductors vendor part/style coilcraft (847) 639-6400 www.coilcraft.com do1606t, mss5131, mss5121 mss6122, mos6020 me3220, do1608c 1812ps coiltronics sd12, sd14, sd20 sd25, sd52 sumida (847) 956-0666 www.sumida.com cd43 cdc5d23b cdrh5d18 tdk vlp, vlf vlcf, slf, vls toko (408) 432-8282 www.tokoam.com d53, d62, d63 d73, d75 wurth (201) 785-8800 www.we-online.com we-tpc type m, mh output and input capacitor selection low esr (equivalent series resistance) 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 10f to 22f output capacitor is suffcient for most ap - plications. values larger than 22f 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. the internal loop compensation of the ltc3528-2 is de - signed to be stable with output capacitor values of 10f or greater. although ceramic capacitors are recommended, low esr tantalum capacitors may be used as well. a small ceramic capacitor in parallel with a larger tantalum capacitor may be used in demanding applications which have large load transients. another method of improving the transient response is to add a small feed-forward capaci - tor across the top resistor of the feedback divider (from v out to fb). a typical value of 68pf will generally suffce. 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 10f input capacitor is suffcient 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 typical applications 1 cell to 1.8v sw v in 499k 2.2h 1m 4.7f 10f 68pf 35282 ta02a ltc3528-2 shdn pgood v out fb v in 0.88v to 1.6v v out 1.8v 250ma off on gnd effciency load current (ma) 0.01 80 90 100 100 35282 ta02b 70 60 0.1 1 10 1000 50 40 30 efficiency (%) v in = 0.9v v in = 1.2v v in = 1.5v
ltc3528-2 14 35282f dual 1 cell to 1.8v, 3v sequenced supply sw v in 499k 475k 2.2h 1m 4.7f 10f ltc3528-2 shdn pgood v out fb v in 0.88v to 1.6v v out1 1.8v 250ma off on gnd sw v in 499k 2.2h 324k 4.7f 10f 68pf 3528 ta03a ltc3528-2 shdn pgood v out fb v out2 3v 200ma gnd 68pf output voltage sequencing v out2 v out1 v in pgood1 200s/div 0.5v/div 35282 ta03b typical applications 1 cell to 3.3v effciency sw v in 499k 2.2h 287k 4.7f 10f 68pf 35282 ta04a ltc3528-2 shdn pgood v out fb v in 0.88v to 1.6v v out 3.3v 200ma off on gnd load current (ma) 0.01 80 90 100 100 35282 ta04b 70 60 0.1 1 10 1000 50 40 30 efficiency (%) v in = 0.9v v in = 1.2v v in = 1.5v
ltc3528-2 15 35282fa typical applications 2 cell to 5v effciency effciency li-ion to 5v sw v in 1m 2.2h 316k 4.7f 22f 68pf 35282 ta06a ltc3528-2 shdn pgood v out fb v in 1.8v to 3.2v v out 5v 300ma off on gnd sw v in 1m 2.2h 316k 4.7f 68pf 35282 ta07a ltc3528-2 shdn pgood v out fb v in 2.7v to 4.2v v out 5v 400ma off on gnd load current (ma) 0.01 80 90 100 100 35282 ta06b 70 60 0.1 1 10 1000 50 40 30 efficiency (%) v in = 1.8v v in = 2.4v v in = 3v load current (ma) 0.01 80 90 100 100 35282 ta07b 70 60 0.1 1 10 1000 50 40 30 efficiency (%) v in = 2.8v v in = 3.6v v in = 4.2v effciency 2 cell to 3.3v sw v in 499k 2.2h 287k 4.7f 10f 68pf 35282 ta05a ltc3528-2 shdn pgood v out fb v in 1.8v to 3.2v v out 3.3v 400ma off on gnd load current (ma) 0.01 80 90 100 100 35282 ta05b 70 60 0.1 1 10 1000 50 40 30 efficiency (%) v in = 1.8v v in = 2.4v v in = 3v
ltc3528-2 16 35282f 2.00 0.10 (2 sides) note: 1. drawing conforms to version (wecd-1) in jedec package outline m0-229 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.40 0.10 bottom view?exposed pad 0.56 0.05 (2 sides) 0.75 0.05 r = 0.115 typ r = 0.05 typ 2.15 0.05 (2 sides) 3.00 0.10 (2 sides) 1 4 8 5 pin 1 bar top mark (see note 6) 0.200 ref 0 ? 0.05 (ddb8) dfn 0905 rev b 0.25 0.05 0.50 bsc pin 1 r = 0.20 or 0.25 45 chamfer 0.25 0.05 2.20 0.05 (2 sides) recommended solder pad pitch and dimensions 0.61 0.05 (2 sides) 1.15 0.05 0.70 0.05 2.55 0.05 package outline 0.50 bsc package description ddb package 8-lead plastic dfn (3mm 2mm) (reference ltc dwg # 05-08-1702 rev b)
ltc3528-2 17 35282fa 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 a 01/11 change in operating temperature range update to note 2 refected in electrical characteristics replaced graphs g14, g15, g16 and g17 operations section update pin 9 to read gnd operations section update to shutdown 2 2,3 5 7 9
ltc3528-2 18 35282f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com linear technology corporation 2009 lt 0111 rev a ? printed in usa related parts part number description comments ltc3528/ltc3528 1a (i sw ), 1mhz synchronous step-up dc/dc converters with output disconnect 94% effciency, v in : 0.7v to 5.5v, v out(max) = 5.25v, i q = 12a, i sd < 1a, 3mm w 2mm dfn8 package ltc3528b-2 1a (i sw ), 2mhz synchronous step-up dc/dc converter with output disconnect 94% effciency, v in : 0.7v to 5.5v, v out(max) = 5.25v, i q = 12a, i sd < 1a, 3mm w 2mm dfn8 package ltc3400/ltc3400b 600ma (i sw ), 1.2mhz, synchronous step-up dc/dc converters 92% effciency v in : 0.85v to 5v, v out(max) = 5v, i q = 19a/300a, i sd < 1a, thinsot tm package ltc3421 3a (i sw ), 3mhz, synchronous step-up dc/dc converter with output disconnect 94% effciency v in : 0.85v to 4.5v, v out(max) = 5.25v, i q = 12a, i sd < 1a, 4mm w 4mm qfn24 package ltc3422 1.5a (i sw ), 3mhz synchronous step-up dc/dc converter with output disconnect 94% effciency v in : 0.85v to 4.5v, v out(max) = 5.25v, i q = 25a, i sd < 1a, 3mm w 3mm dfn10 package ltc3426 2a (i sw ), 1.5mhz, step-up dc/dc converter 92% effciency v in : 1.6v to 5.5v, v out(max) = 5v, i q = 600a, i sd < 1a, thinsot package ltc3427 500ma (i sw ), 1.25mhz, synchronous step-up dc/dc converter with output disconnect 94% effciency v in : 1.8v to 5v, v out(max) = 5.25v, i q = 350a i sd < 1a, 2mm w 2mm dfn6 package ltc3429/ltc3429b 600ma (i sw ), 550khz, synchronous step-up dc/dc converter with output disconnect and soft-start 96% effciency v in : 0.85v to 4.3v, v out(max) = 5v, i q = 20a, i sd < 1a, thinsot package ltc3458/ltc3458l 1.4a/1.7a (i sw ), 1.5mhz, synchronous step-up dc/dc converter 94% effciency v in : 0.85v to 6v, v out(max) = 7.5v/6v, i q = 15a, i sd < 1a, 3mm w 4mm dfn12 package ltc3459 80ma (i sw ), synchronous step-up dc/dc converter 92% effciency v in : 1.5v to 5.5v, v out(max) = 10v, i q = 10a, i sd < 1a, thinsot package lt ? 3494/lt3494a 180ma/350ma (i sw ), high effciency step-up dc/dc converter with output disconnect 85% effciency v in : 2.3v to 16v, v out(max) = 38v, i q = 65a, i sd < 1a, 2mm w 3mm dfn6, thinsot packages ltc3523/ltc3523-2 600ma (i sw ), step-up and 400ma synchronous step-down 1.2mhz/2.4mhz dc/dc converters with output disconnect 94% effciency v in : 1.8v to 5.5v, v out(max) = 5.25v, i q = 45a, i sd < 1a, 3mm w 3mm qfn16 ltc3526/ltc3526l ltc3526b 500ma (i sw ), 1mhz synchronous step-up dc/dc converters with output disconnect 94% effciency, v in : 0.85v to 5v, v out(max) = 5.25v, i q = 9a, i sd < 1a, 2mm w 2mm dfn6 package ltc3527/ltc3527-1 dual 800ma/400ma (i sw ), 2.2mhz, synchronous step-up dc/dc converter with output disconnect 94% effciency, v in : 0.7v to 5v, v out(max) = 5.25v, i q = 12a, i sd < 1a, 3mm w 3mm qfn16 package ltc3537 600ma, 2.2mhz synchronous step-up dc/dc converter with output disconnect and 100ma ldo 94% effciency, v in : 0.7v to 5v, v out(max) = 5.25v, i q = 30a, i sd < 1a, 3mm w 3mm qfn16 package
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn l l l l l l l l l l l step-up (boost) regulators home > products > power management > switching regulator > step-up (boost) regulators > micropower boost > ltc3528-2 l micropower boost l internal power switch boost l multiple output boost l external power switch boost ltc3528-2 - 1a, 2mhz synchronous step- up dc/dc converter in 2mm 3mm dfn l l l l l http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (1 of 6) [24-jan-2011 8:20:55 am]
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn l print friendly features l delivers 3.3v at 200ma from a single alkaline/ nimh cell or 3.3v at 400ma from two cells l v in start-up voltage: 700mv l 0.50v to 5.5v input range l 1.6v to 5.25v v out range l up to 94% efficiency l output disconnect l 2mhz fixed frequency operation l v in > v out operation l integrated soft-start l current mode control with internal compensation l burst mode? operation with 12?a quiescent current l internal synchronous rectifier l logic controlled shutdown: <1?a l anti-ringing control l low profile (2mm 3mm 0.75mm) dfn package typical application http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (2 of 6) [24-jan-2011 8:20:55 am]
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn back to top description the ltc3528-2 is a synchronous, fixed frequency step-up dc/dc converter with output disconnect. high efficiency synchronous rectification, in addition to a 700mv startup voltage and operation down to 500mv once started, provides longer run-time for single or multiple cell battery- powered products. a switching frequency of 2mhz minimizes solution footprint by allowing the use of tiny, low profile inductors and ceramic capacitors. the current mode pwm is internally compensated, simplifying the design process. the ltc3528-2 enters burst mode operation at light loads. anti-ringing circuitry reduces emi by damping the inductor in discontinuous mode. additional features include a low shutdown current, open-drain power good output, shortcircuit protection and thermal overload protection. the ltc3528-2 is offered in an 8-lead 2mm 3mm 0.75mm dfn package. back to top packaging dfn-8 http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (3 of 6) [24-jan-2011 8:20:55 am]
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn back to top order info l part numbers ending in pbf are lead free. please contact ltc marketing for information on lead based finish parts. l part numbers containing tr or trm are shipped in tape and reel or 500 unit mini tape and reel, respectively l please refer to our general ordering information or the product datasheet for more details package variations and pricing part number package pins temp price (1-99) price (1k) * rohs data ltc3528beddb#pbf dfn 8 e $2.79 view ltc3528beddb#trmpbf dfn 8 e $2.79 $2.00 view ltc3528beddb#trpbf dfn 8 e $2.79 $1.95 view ltc3528beddb-2#pbf dfn 8 e $2.79 view ltc3528beddb-2#trmpbf dfn 8 e $2.79 $2.00 view ltc3528beddb-2#trpbf dfn 8 e $2.79 $1.95 view ltc3528eddb#pbf dfn 8 e $2.79 view ltc3528eddb#trmpbf dfn 8 e $2.79 $2.00 view ltc3528eddb#trpbf dfn 8 e $2.79 $1.95 view ltc3528eddb-2#pbf dfn 8 e $2.79 view ltc3528eddb-2#trmpbf dfn 8 e $2.79 $2.00 view ltc3528eddb-2#trpbf dfn 8 e $2.79 $1.95 view http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (4 of 6) [24-jan-2011 8:20:55 am]
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn buy now request samples * the usa list pricing shown is for budgetary use only, shown in united states dollars (fob usa per unit for the stated volume), and is subject to change. international prices may differ due to local duties, taxes, fees and exchange rates. for volume-specific price or delivery quotes, please contact your local linear technology sales office or authorized distributor. back to top applications l medical instruments l noise canceling headphones l wireless mice l bluetooth headsets back to top simulate to simulate selected linear technology products, please download ltspice / switchercad iii. this powerful schematic capture and simulation tool includes macro models for 80% of linear technology's switching regulators, over 200 op amp models, as well as resistors, transistors and mosfet models. for other simulation tools, visit our design simulation and device models page. back to top order now request samples documentation datasheet l ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (5 of 6) [24-jan-2011 8:20:55 am]
linear technology - ltc3528-2 - 1a, 2mhz synchronous step-up dc/dc converter in 2mm 3mm dfn l site help l site map l site index l send us feedback l ? 2007 linear technology | terms of use | privacy policy http://www.linear.com/pc/productdetail.jsp?navid=h0,c1,c1003,c1042,c1031,c1060,p88383 (6 of 6) [24-jan-2011 8:20:55 am]

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