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1 ltc1754-3.3/ltc1754-5 micropower, regulated 3.3v/5v charge pump with shutdown in sot-23 n ultralow power: i in = 13 m a n regulated output voltage: 3.3v 4%, 5v 4% n 5v output current: 50ma (v in 3 3.0v) n 3.3v output current: 40ma (v in 3 2.5v) n no inductors needed n very low shutdown current: <1 m a n shutdown disconnects load from v in n internal oscillator: 600khz n short-circuit and overtemperature protected n ultrasmall application circuit: (0.052 inch 2 ) n 6-pin sot-23 package n sim interface supplies for gsm cellular telephones n white led power supplies n li-ion battery backup supplies n handheld computers n smart card readers n pcmcia local 5v supplies the ltc ? 1754 is a micropower charge pump dc/dc converter that produces a regulated output. the input voltage range is 2v to 4.4v for 3.3v output and 2.7v to 5.5v for 5v output. extremely low operating current and a low external parts count (one flying capacitor and two small bypass capacitors at v in and v out ) make the ltc1754 ideally suited for small, battery-powered applications. the total component area of the application circuit shown below is only 0.052 inch 2 . the ltc1754 operates as a burst mode tm switched capaci- tor voltage doubler to produce a regulated output. it has thermal shutdown capability and can survive a continuous short circuit from v out to gnd. the ltc1754 is available in a 6-pin sot-23 package. , ltc and lt are registered trademarks of linear technology corporation. burst mode is a trademark of linear technology corporation. ltc1754-5 output voltage vs supply voltage features descriptio u applicatio s u typical applicatio u supply voltage (v) 2.5 4.85 output voltage (v) 4.90 4.95 5.00 5.05 5.15 3.0 3.5 4.0 4.5 1574 ta03 5.0 5.5 5.10 t a = 40 c t a = 85 c i out = 25ma c out = 10 f c fly = 1 f t a = 25 c supply voltage (v) 2.0 output voltage (v) 3.30 3.35 4.0 1754 ta02 3.25 3.20 2.5 3.0 3.5 4.5 3.40 i out = 20ma c out = 10 f c fly = 1 f t a = 85 c t a = 25 c t a = 40 c ltc1754-3.3 output voltage vs supply voltage 1 ltc1754-x regulated 3.3v output from 2v to 4.4v input regulated 5v output from 2.7v to 5.5v input 2 3 6 5 4 on/off v out 1754 ta01 v in v out v out = 5v 4% i out = 0ma to 25ma, v in > 2.7v i out = 0ma to 50ma, v in > 3.0v 10 m f 1 m f 10 m f gnd shdn c + v in c v out = 3.3v 4% i out = 0ma to 20ma, v in > 2.0v i out = 0ma to 40ma, v in > 2.5v
2 ltc1754-3.3/ltc1754-5 order part number consult factory for industrial and military grade parts. (note 1) v in to gnd .................................................. C 0.3v to 6v v out to gnd ............................................... C 0.3v to 6v shdn to gnd .............................................. C 0.3v to 6v i out (note 4) ......................................................... 75ma v out short-circuit duration ............................ indefinite operating temperature range (note 3) ... C 40 c to 85 c storage temperature range .................. C 65 c to 150 c lead temperature (soldering, 10 sec)................... 300 c ltc1754es6-3.3 ltc1754es6-5 t jmax = 150 c, q ja = 230 c/ w s6 part marking ltgk ltlw the l denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. c fly = 1 m f (note 2), c in = 10 m f, c out = 10 m f. v out 1 gnd 2 shdn 3 6 c + 5 v in 4 c top view s6 package 6-lead plastic sot-23 note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: 0.6 m f is the minimum required c fly capacitance for rated output current capability. depending on the choice of capacitor material, a somewhat higher value of capacitor may be required to attain 0.6 m f over temperature. note 3: the ltc1754es6-x is guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C40 c to 85 c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 4: based on long term current density limitations. symbol parameter conditions min typ max units ltc1754-3.3 v in input supply voltage l 2.0 4.4 v v out output voltage 2.0v v in 4.4v, i out 20ma l 3.17 3.30 3.43 v 2.5v v in 4.4v, i out 40ma l 3.17 3.30 3.43 v i cc operating supply current 2.0v v in 4.4v, i out = 0ma, shdn = v in l 11 30 m a v r output ripple v in = 2.5v, i out = 40ma 23 mv p-p h efficiency v in = 2.0v, i out = 20ma 82 % f osc switching frequency oscillator free running 600 khz t on v out turn-on time v in = 2.0v, i out = 0ma 0.8 ms i sc output short-circuit current v in = 2.5v, v out = 0v, shdn = 2.5v 118 ma ltc1754-5 v in input supply voltage l 2.7 5.5 v v out output voltage 2.7v v in 5.5v, i out 25ma l 4.8 5.0 5.2 v 3.0v v in 5.5v, i out 50ma l 4.8 5.0 5.2 v i cc operating supply current 2.7v v in 5.5v, i out = 0ma, shdn = v in l 13 30 m a v r output ripple v in = 3v, i out = 50ma 65 mv p-p h efficiency v in = 3v, i out = 50ma 82.7 % f osc switching frequency oscillator free running 700 khz t on v out turn-on time v in = 3v, i out = 0ma 0.4 ms i sc output short-circuit current v in = 3v, v out = 0v, shdn = 3v 150 ma ltc1754-3.3/ltc1754-5 i shdn shutdown supply current v in 3.6v, i out = 0ma, v shdn = 0v l 0.01 1 m a 3.6v < v in , i out = 0ma, v shdn = 0v l 2.5 m a v ih shdn input threshold (high) l 1.4 v v il shdn input threshold (low) l 0.3 v i ih shdn input current (high) shdn = v in l C1 1 m a i il shdn input current (low) shdn = 0v l C1 1 m a absolute axi u rati gs w ww u package/order i for atio uu w electrical characteristics
3 ltc1754-3.3/ltc1754-5 typical perfor a ce characteristics uw ltc1754-3.3, t a = 25 c unless otherwise noted. no load supply current vs supply voltage output voltage vs output current supply current vs v shdn output current (ma) 0 output voltage (v) 3.30 3.35 80 1754 g01 3.25 3.20 20 40 60 100 3.40 t a = 25 c c out = 10 f c fly = 1 f v in = 2.5v v in = 2v supply voltage (v) 2.0 5 supply current ( a) 10 15 20 2.5 3.0 3.5 4.0 1754 g02 4.5 i out = 0 a c fly = 1 f v shdn = v in t a = 85 c t a = 25 c t a = 40 c v shdn control voltage (v) 1 supply current ( a) 10 15 5 1754 g03 5 0 2 3 4 20 t a = 25 c i out = 0 a v in = 4.5v v in = 2.5v v in = 2v efficiency vs load current v out short-circuit current vs supply voltage supply voltage (v) 2.0 60 v out short-circuit current (ma) 80 100 120 140 160 180 2.5 3.0 3.5 4.0 1735 g04 4.5 t a = 25 c c fly = 1 f load current (ma) 0.001 40 efficiency (%) 50 60 70 80 0.01 0.1 1 10 100 1754 g05 30 20 10 0 90 100 t a = 25 c v in = 2v c fly = 1 f output ripple load transient response start-up time i out 0ma to 20ma 10ma/div v out ac coupled 20mv/div v in = 2v 50 m s/div 1754 g07 c out = 10 m f v out ac coupled 20mv/div v in = 2v 5 m s/div 1754 g08 c out = 10 m f i out = 20ma shdn 1v/div v out 1v/div v in = 2v 200 m s/div 1754 g9 c out = 10 m f
4 ltc1754-3.3/ltc1754-5 typical perfor a ce characteristics uw ltc1754-5, t a = 25 c unless otherwise noted. no load supply current vs supply voltage output voltage vs output current supply current vs v shdn efficiency vs load current v out short-circuit current vs supply voltage output ripple load transient response start-up time i out 0ma to 50ma 25ma/div v out ac coupled 50mv/div v in = 3v 50 m s/div 1754 g16 c out = 10 m f v out ac coupled 20mv/div v in = 3v 5 m s/div 1754 g17 c out = 10 m f i out = 50ma shdn 5v/div v out 1v/div v in = 3v 100 m s/div 1754 g18 c out = 10 m f output current (ma) 0 4.85 output voltage (v) 4.90 4.95 5.00 5.05 5.10 5.15 20 40 60 80 1574-5 g02 100 t a = 25 c c out = 10 f c fly = 1 f v in = 3v v in = 2.7v supply voltage (v) supply current ( a) 4.0 4.5 1754 g11 2.5 3.0 3.5 5.0 5.5 20 15 10 5 i out = 0 a c fly = 1 f v shdn = v in t a = 85 c t a = 40 c t a = 25 c v shdn control voltage (v) 1 supply current ( a) 15 20 25 5 1574 g12 10 5 0 2 3 4 6 t a = 25 c i out = 0 a v in = 5.5v v in = 3.3v v in = 2.7v supply voltage (v) v out short-circuit current (ma) 4.0 4.5 1754 g13 2.5 3.0 3.5 5.0 5.5 220 180 140 200 160 120 100 t a = 25 c c fly = 1 f load current (ma) 0.001 40 efficiency (%) 50 60 70 80 0.01 0.1 1 10 100 1754-5 g05 30 20 10 0 90 100 v in = 3v t a = 25 c c fly = 1 f
5 ltc1754-3.3/ltc1754-5 v out (pin 1): regulated output voltage. for best perfor- mance, v out should be bypassed with a 6.8 m f (min) low esr capacitor as close as possible to the pin. gnd (pin 2): ground. should be tied to a ground plane for best performance. shdn (pin 3): active low shutdown input. a low on shdn disables the ltc1754. shdn must not be allowed to float. c C (pin 4): flying capacitor negative terminal. v in (pin 5): input supply voltage. v in should be bypassed with a 6.8 m f (min) low esr capacitor. c + (pin 6): flying capacitor positive terminal. si plified w block diagra w typical perfor a ce characteristics uw ltc1754-3.3. ltc1754-5, t a = 25 c unless otherwise noted. oscillator frequency vs supply voltage efficiency vs supply voltage supply voltage (v) 2.0 70 80 100 3.5 4.5 1754 g19 60 50 2.5 3.0 4.0 5.0 5.5 40 30 90 efficiency (%) t a = 25 c c fly = 1 f ltc1754-5 i out = 25ma ltc1754-3.3 i out = 20ma supply voltage (v) 2.0 oscillator frequency (khz) 800 3.5 1754 g20 650 550 2.5 3.0 4.0 500 450 850 750 700 600 4.5 5.0 5.5 t a = 85 c t a = 25 c t a = 40 c supply voltage (v) 2.0 threshold voltage (v) 0.85 0.90 0.95 3.5 4.5 1754 g21 0.80 0.75 2.5 3.0 4.0 5.0 5.5 0.70 0.65 t a = 40 c t a = 25 c t a = 85 c + comp1 2 * c + c fly 1 m f c *charge pump shown in phase 1, the charging phase. phase 1 is also the shutdown phase 1 1 2 control v ref c out 10 m f c in 10 m f v in 1754 bd v out shdn v shdn threshold voltage vs supply voltage uu u pi fu ctio s
6 ltc1754-3.3/ltc1754-5 operation (refer to block diagram) the ltc1754 uses a switched-capacitor charge pump to boost v in to a regulated output voltage. regulation is achieved by sensing the output voltage through an internal resistor divider and enabling the charge pump when the divided output drops below the lower trip point of comp1. when the charge pump is enabled, a two-phase nonoverlapping clock activates the charge pump switches. the flying capacitor is charged to v in on phase one of the clock. on phase two of the clock it is stacked in series with v in and connected to v out . this sequence of charging and discharging the flying capacitor continues at a free run- ning frequency of 600khz (typ). once the attenuated output voltage reaches the upper trip point of comp1, the charge pump is disabled. when the charge pump is disabled the ltc1754 draws only 13 m a from v in thus providing high efficiency under low load conditions. in shutdown mode all circuitry is turned off and the ltc1754 draws only leakage current from the v in supply. furthermore, v out is disconnected from v in . the shdn pin is a cmos input with a threshold voltage of approxi- mately 0.8v, but may be driven to a logic level that exceeds v in . the ltc1754 is in shutdown when a logic low is applied to the shdn pin. since the shdn pin is a high impedance cmos input, it should never be allowed to float. to ensure that its state is defined, it must always be driven with a valid logic level. power efficiency the efficiency ( h ) of the ltc1754 is similar to that of a linear regulator with an effective input voltage of twice the actual input voltage. this results because the input current for a voltage doubling charge pump is approximately twice the output current. in an ideal voltage doubling regulator the power efficiency would be given by: h= = ()() ()( ) = p p vi vi v v out in out out in out out in 2 2 at moderate-to-high output power, the switching losses and quiescent current of the ltc1754 are negligible and the expression above is valid. for example, an ltc1754-5 with v in = 3v, i out = 25ma and v out regulating to 5v, has a mea sured efficiency of 82.7%, which is in close agreement with the theoretical 83.3% calculation. the ltc1754 con- tinues to maintain good efficiency even at fairly light loads because of its inherently low power design. short-circuit/thermal protection during short-circuit conditions, the ltc1754 will draw between 100ma and 400ma from v in causing a rise in the junction temperature. on-chip thermal shutdown circuitry disables the charge pump once the junction temperature exceeds approximately 150 c and reenables the charge pump once the junction temperature drops back to ap- proximately 140 c. the ltc1754 will cycle in and out of thermal shutdown indefinitely without latchup or damage until the short circuit on v out is removed. capacitor selection the style and value of capacitors used with the ltc1754 determine several important parameters such as output ripple, charge pump strength and turn-on time. to reduce noise and ripple, it is recommended that low esr (< 0.1 w ) capacitors be used for both c in and c out . these capacitors should be either ceramic or tantalum and be 6.8 m f or greater. aluminum capacitors are not recom- mended because of their high esr. if the source imped- ance to v in is very low up to several megahertz, c in may not be needed. a ceramic capacitor is recommended for the flying capaci- tor with a value in the range of 1 m f to 2.2 m f. note that a large value flying capacitor (> 2.2 m f) will increase output ripple unless c out is also increased. for very low load applications, c fly may be reduced to 0.01 m f to 0.047 m f. this will reduce output ripple at the expense of maximum output current and efficiency. in order to achieve the rated output current it is necessary to have at least 0.6 m f of capacitance for the flying capaci- tor. capacitors of different material lose their capacitance over temperature at different rates. for example, a ceramic capacitor made of x7r material will retain most of its capacitance from C 40 c to 85 c, whereas a z5u or y5v style capacitor will lose considerable capacitance over that applicatio s i for atio wu uu
7 ltc1754-3.3/ltc1754-5 range. the capacitor manufacturers data sheet should be consulted to determine what style and value of capacitor is needed to ensure 0.6 m f at all temperatures. output ripple low frequency regulation mode ripple exists due to the hysteresis in the sense comparator and propagation delay in the charge pump control circuit. the amplitude and frequency of this ripple are heavily dependent on the load current, the input voltage and the output capacitor size. for large v in the ripple voltage can become substantial because the increased strength of the charge pump causes fast edges that may outpace the regulation circuitry. generally the regulation ripple has a sawtooth shape associated with it. a high frequency ripple component may also be present on the output capacitor due to the charge transfer action of the charge pump. in this case the output can display a voltage pulse during the charging phase. this pulse results from the product of the charging current and the esr of the output capacitor. it is proportional to the input voltage, the value of the flying capacitor and the esr of the output capacitor. typical combined output ripple for the ltc1754-5 with v in = 3v under maximum load is 65mv p-p using a low esr 10 m f output capacitor. a smaller output capacitor and/or larger output current load will result in higher ripple due to higher output voltage slew rates. there are several ways to reduce output voltage ripple. for applications requiring higher v in or lower peak-to-peak ripple, a larger c out capacitor (22 m f or greater) is recom- mended. a larger capacitor will reduce both the low and high frequency ripple due to the lower charging and discharging slew rates, as well as the lower esr typically found with higher value (larger case size) capacitors. a low esr ceramic output capacitor will minimize the high frequency ripple, but will not reduce the low frequency ripple unless a high capacitance value is used. to reduce both the low and high frequency ripple, a reasonable compromise is to use a 10 m f to 22 m f tantalum capacitor in parallel with a 1 m f to 3.3 m f ceramic capacitor on v out . an r-c filter may also be used to reduce high frequency voltage spikes (see figure 1). figure 1. output ripple reduction techniques in low load or high v in applications, smaller values for the flying capacitor may be used to reduce output ripple. a smaller flying capacitor (0.01 m f to 0.47 m f) delivers less charge per clock cycle to the output capacitor resulting in lower output ripple. however, with a smaller flying capaci- tor, the maximum available output current will be reduced along with the efficiency. note that when using a larger output capacitor the turn on time of the device will increase. inrush currents during normal operation v in will experience current tran- sients in the 50ma to 100ma range whenever the charge pump is enabled. however during start-up, inrush cur- rents may approach 250ma. for this reason it is important to minimize the source impedance between the input supply and the v in pin. too much source impedance may result in regulation problems or prevent start-up. ultralow quiescent current regulated supply the ltc1754 contains an internal resistor divider (refer to the simplified block diagram) that typically draws 1.5 m a from v out . during no-load conditions, this internal load causes a droop rate of only 150mv per second on v out with c out = 10 m f. applying a 2hz to 100hz, 2% to 5% duty cycle signal to the shdn pin ensures that the circuit of figure 2 comes out of shutdown frequently enough to maintain regulation. since the ltc1754 spends nearly the entire time in shutdown, the no-load quiescent current is approximately (v out )(1.5 m a)/( h v in ). the ltc1754 must be out of shutdown for a minimum duration of 200 m s to allow enough time to sense the output voltage and keep it in regulation. a 2hz, 2% duty cycle ltc1754-x 15 m f tantalum v out v out v out 1 m f ceramic ltc1754-x 2 10 m f tantalum 10 m f tantalum v out 1754 f01 + + + applicatio s i for atio wu uu
8 ltc1754-3.3/ltc1754-5 layout considerations due to high switching frequency and high transient cur- rents produced by the ltc1754, careful board layout is necessary. a true ground plane and short connections to all capacitors will improve performance and ensure proper regulation under all conditions. figure 4 shows the recom- mended layout configuration figure 4. recommended layout signal will keep v out in regulation under no-load condi- tions. as the v out load current increases, the frequency with which the ltc1754 is taken out of shutdown must also be increased. figure 2. ultralow quiescent current regulated supply figure 3. no-load supply current vs supply voltage for the circuit shown in figure 2 supply voltage (v) 2.0 supply current ( a) 4 5 6 3.5 4.5 1754 f03 3 2 2.5 3.0 4.0 5.0 5.5 1 0 t a = 25 c i out = 0 a c fly = 1 f ltc1754-5 ltc1754-3.3 ltc1754-x v in v out gnd 1754-5 f04 shdn 10 m f 10 m f 1 m f c + 1 2 3 6 5 4 ltc1754-x v in c v out 1754 f02 v in v out low i q mode (2hz to 100hz, 2% to 5% duty cycle) 10 m f 1 m f 10 m f shdn pin waveform gnd shdn thermal management for higher input voltages and maximum output current, there can be substaintial power dissipation in the ltc1754. if the junction temperature increases above approximately 150 c, the thermal shutdown circuitry will automatically deactivate the output. to reduce the maximum junction temperature, a good thermal connection to the pc board is recommended. connecting the gnd pin (pin 2) to a ground plane and maintaining a solid ground plane under the device on at least two layers of the pc board can reduce the thermal resistance of the package and pc board system to about 150 c/w. applicatio s i for atio wu uu
9 ltc1754-3.3/ltc1754-5 typical applicatio s u low power battery backup with autoswitchover and no reverse current c 1 f c + v in 46 1 3 2 1 5 + 4 3 6 10k 1.2m 5 2 175433 ta03 1 8 high = backup mode 3 2 7 10 f v out = 3.3v i out 300ma i out 20ma backup v out ltc1754-3.3 ltc1540 shdn gnd 10 f 2-cell nicd battery 10 f 75k 1n4148 v in 5v 475k 1m ltc1521-3.3 5 46 ltc1754-5 1 f 3 1 2 1754 ta06 10 m f 10 m f v out 5v 4% 50ma usb port to regulated 5v power supply
10 ltc1754-3.3/ltc1754-5 5v, 100ma step-up generator from 3v typical applicatio s u c c + v in 46 v out ltc1754-5 gnd shdn 1 2 5 v in 3v v out 5v 100ma on/off 1 f 3 10 f c c + v in 46 v out ltc1754-5 gnd shdn 1 2 5 1 f 3 10 f 1754 ta07 lithium-ion battery to 5v white or blue led driver on/off 3v to 4.4v li-ion battery c c + v in 46 v out ltc1754-5 gnd shdn 1 2 5 1 f 3 100 1754 ta08 10 f 10 f 100 100 3.3v and 5v step-up generator from 2v on/off v in 2v c c + v in 46 v out ltc1754-3.3 gnd shdn 1 2 5 1 f1 f 3 1754 ta09 10 f 10 f c c + v in 46 v out ltc1754-5 gnd shdn 1 2 5 3 10 f v out1 3.3v i 3.3 + 2i 5 20ma v out2 5v 3.3i 3.3 + 5i 5 v in (2i 3.3 + 4i 5 ) h @
11 ltc1754-3.3/ltc1754-5 package descriptio n u dimensions in inches (millimeters), unless otherwise noted. s6 package 6-lead plastic sot-23 (ltc dwg # 05-08-1634) 0.95 (0.037) ref 1.50 ?1.75 (0.059 ?0.069) 0.35 ?0.55 (0.014 ?0.022) 0.35 ?0.50 (0.014 ?0.020) six places (note 2) s6 sot-23 0898 2.80 ?3.00 (0.110 ?0.118) (note 3) 1.90 (0.074) ref 0.90 ?1.45 (0.035 ?0.057) 0.90 ?1.30 (0.035 ?0.051) 0.00 ?0.15 (0.00 ?0.006) 0.09 ?0.20 (0.004 ?0.008) (note 2) 2.6 ?3.0 (0.110 ?0.118) note: 1. dimensions are in millimeters 2. dimensions are inclusive of plating 3. dimensions are exclusive of mold flash and metal burr 4. mold flash shall not exceed 0.254mm 5. package eiaj reference is sc-74a (eiaj) 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.
12 ltc1754-3.3/ltc1754-5 175435f lt/tp 0400 4k ? printed in usa ? linear technology corporation 1999 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com part number description comments lt1054 high power doubler charge pump up to 100ma output, v in = 3.5v to 15v, so-8 package ltc1144 charge pump inverter with shutdown v in = 2v to 18v, 15v to C15v supply ltc1262 12v, 30ma flash memory prog. supply regulated 12v 5% output, i q = 500 m a ltc1514/ltc1515 buck/boost charge pumps with i q = 60 m a 50ma output at 3v, 3.3v or 5v; 2v to 10v input ltc1516 micropower 5v charge pump i q = 12 m a, up to 50ma output, v in = 2v to 5v ltc1517-5/ltc1517-3.3 micropower 5v/3.3v doubler charge pumps i q = 6 m a, up to 20ma output ltc1522 micropower 5v doubler charge pump i q = 6 m a, up to 20ma output lt1615 step-up switching regulator in sot-23 i q = 20 m a, v in = 1.2v to 15v, up to 34v output ltc1682 low noise doubler charge pump output noise = 60 m v rms , 2.5v to 5.5v output related parts low power battery backup with autoswitchover and no reverse current c 1 f si4435dy c + v in 46 1 5 + 4 3 6 10k 1.43m 5 2 1754 ta05 1 8 3 2 7 10 f v out = 5v i out 50ma v out ltc1754-5 ltc1540 shdn gnd bat54c 10 f 3-cell nicd battery 10 f 75k 1n4148 v in 5v 475k 1m typical applicatio u

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