1 ltc1517-3.3 micropower, regulated 3.3v charge pump in a 5-pin sot-23 package features descriptio n u n ultralow power: i cc = 6 m a typ n short-circuit/thermal protected n 3.3v 4% regulated output n v in range: 2v to 4.4v n output current: 8ma (v in 3 2v) 15ma (v in 3 2.5v) n no inductors n ultrasmall application circuit (0.045in 2 ) n 700khz switching frequency n available in 5-pin sot-23 the ltc ? 1517-3.3 is a micropower charge pump dc/dc converter that produces a regulated 3.3v output. the input voltage range is 2v to 4.4v, allowing a single cell lithium battery to produce a regulated 3.3v output over the entire life of the battery. extremely low operating current (typically 6 m a with no load) and low external parts count (one 0.1 m f flying capacitor and two small bypass capacitors at v in and v out ) make the part ideally suited for small, light load battery- powered applications. the total printed circuit board area of the application circuit shown below is only 0.045in 2 . the part operates as a burst mode tm switched-capacitor voltage doubler to produce a regulated output. the part has thermal shutdown capability and can survive a continuous short circuit from v out to gnd. the device is available in a 5-pin sot-23 package. n cellular telephones n battery-operated equipment n local power supplies n handheld instruments n pcmcia supplies applicatio n s u , ltc and lt are registered trademarks of linear technology corporation. burst mode is a trademark of linear technology corporation. typical applicatio n u 3.3 f 1517-3.3 ta01 123 4 5 0.1 f 6.8 f v out = 3.3v 4%
i out = 8ma (v in 3 2v)
i out = 15ma (v in 3 2.5v) v in
2v to 4.4v v in gnd ltc1517-3.3 v out c1 + c1 output current (ma) 0 output voltage (v) 40 1517 g05 10 20 30 3.40
3.35
3.30
3.25
3.20 t a = 25 c
c1 = 0.1 f
c out = 6.8 f v in = 2v v in = 2.5v typical output voltage vs output current
2 ltc1517-3.3 absolute m axi m u m ratings w ww u package/order i n for m atio n w u u order part number consult factory for industrial and military grade parts. symbol parameter conditions min typ max units v in operating input voltage l 2.0 4.4 v v out output voltage 2v v in 4.4v, i out 8ma l 3.17 3.3 3.43 v 2.5v v in 4.4v, i out 15ma l 3.17 3.3 3.43 v i cc input supply current 2v v in 4.4v, i out = 0 l 615 m a v out ripple v in = 2.5v, i out = 15ma, c out = 6.8 m f50mv p-p f osc oscillator frequency 700 khz t on v out turn-on time v in = 2.5v 1 ms i sc output short-circuit current v in = 3v 60 ma v in = 2v to 4.4v, c1 = 0.1 m f, c in = 3.3 m f, c out = 6.8 m f, t min to t max , unless otherwise noted. electrical characteristics c1 5
c1 + 1
2
3 v in top view s5 package
5-lead plastic sot-23 v out gnd 4 (note 1) v in to gnd ...................................................C 0.3v to 6v v out to gnd ................................................C 0.3v to 6v v out short-circuit duration ............................. indefinite operating temperature range: commercial (note 2) .............................. 0 c to 70 c storage temperature range ................. C 65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c s5 part marking ltef ltc1517cs5-3.3 t jmax = 125 c, q ja = 256 c/ w the l denotes specifications that apply over the full operating temperature range. note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired. note 2: commercial grade parts are designed to operate over the temperature range of C 40 c to 85 c but are neither tested nor guaranteed beyond 0 c to 70 c.
3 ltc1517-3.3 typical perfor m a n ce characteristics uw input voltage (v) 2.0 output voltage (v) 4.0 1517 g01 2.5 3.0 3.5 4.5 3.40
3.35
3.30
3.25
3.20 i out = 8ma
c out = 6.8 f t a = 70 c t a = 0 c t a = 25 c output voltage vs input voltage input voltage (v) 2.0 efficiency (%) 4.0 1517 g02 2.5 3.0 3.5 4.5 100
80
60
40
20 i out = 8ma
t a = 25 c efficiency vs input voltage input voltage (v) 2.0 v ripple p-p (mv) 4.0 1517 g03 2.5 3.0 3.5 4.5 200
150
100
50
0 i out = 8ma
c1 = 0.1 f
c in = 3.3 f
t a = 25 c c out = 3.3 f c out = 6.8 f c out = 10 f output ripple vs input voltage load transient response i out 0ma to 10ma 5ma/div v out ac coupled 50mv/div v in = 2.5v 500 m s/div c out = 6.8 m f 1517 g06 no load input current vs input voltage input voltage (v) 2.0 input current ( a) 4.0 1517 g04 2.5 3.0 3.5 4.5 10
8
6
4
2 i out = 0ma t a = 70 c t a = 0 c t a = 25 c temperature ( c) ?0 output current (ma) 50
40
30
20
10
0 ?5 02550 1517 g09 75 100 v out = 3.3v
c1 = 0.1 f v in = 2.7v v in = 2.5v v in = 2v typical output current vs temperature input voltage (v) 2.0 v out short-circuit current (ma) 200
160
120
80
40
0 4.0 1517 g10 2.5 3.0 3.5 4.5 t a = 25 c
c1 = 0.1 f v out short-circuit current vs input voltage output current (ma) 0.001 efficiency (%) 100
80
60
40
20
0 10 1517 ta02 0.01 0.1 1 100 t a = 25 c
c1 = 0.1 f
c out = 6.8 f v in = 2v v in = 2.5v typical efficiency vs output current
4 ltc1517-3.3 typical perfor m a n ce characteristics uw si plified w block diagra w 1517-3.3 bd c1
0.1 f v in charge pump v out 2.05m 1.25m c out c in c1 + c1 700khz
osc thermal
shdn 1.25v
ref + v in (pin 1): charge pump input voltage. may be between 2v and 4.4v. v in should be bypassed with a 3 3.3 m f low esr capacitor as close as possible to the pin for best performance. gnd (pin 2): ground. should be tied to a ground plane for best performance. v out (pin 3): regulated output voltage. v out should be bypassed with a 3 3.3 m f low esr capacitor as close as possible to the pin for best performance. pi n fu n ctio n s uuu c1 + (pin 4): charge pump flying capacitor positive terminal. c1 C (pin 5): charge pump flying capacitor negative terminal. oscillator frequency vs input voltage input voltage (v) 2.0 oscillator frequency (khz) 4.0 1517 g07 2.5 3.0 3.5 4.5 900
800
700
600
500 t a = 25 c oscillator frequency vs temperature temperature ( c) ?0 oscillator frequency (khz) 900
800
700
600
500
400 ?5 02550 1517 g08 75 100 v in = 2.5v
5 ltc1517-3.3 applicatio n s i n for m atio n wu u u output ripple normal ltc1517-3.3 operation produces voltage ripple on the v out pin. output voltage ripple is required for the parts to regulate. low frequency ripple exists due to the hysteresis in the sense comparator and propagation de- lays in the charge pump enable/disable circuits. high frequency ripple is also present mainly from the esr (equivalent series resistance) in the output capacitor. typical output ripple with v in = 2.5v under maximum load is 75mv peak-to-peak with a low esr 3.3 m f output capaci- tor (minimum recommended c out ). for applications requiring v in to exceed 3.3v or for applications requiring less than 75mv of peak-to-peak ripple, a 6.8 m f to 10 m f c out capacitor is recommended. slight further decreases in output ripple can be achieved by using c out capacitors larger than 10 m f. short-circuit/thermal protection during short-circuit conditions, the ltc1517-3.3 will draw between 20ma and 150ma from v in , causing a rise in junction temperature. on-chip thermal shutdown circuitry disables the charge pump once the junction temperature exceeds approximately 160 c. the charge pump is reenabled once the junction temperature drops to approxi- mately 145 c. the ltc1517-3.3 will cycle in and out of thermal shutdown indefinitely without latchup or damage until the v out short is removed. operation the ltc1517-3.3 uses a switched-capacitor charge pump to boost v in to a 3.3v 4% regulated output. the part achieves regulation by sensing the output voltage through an internal resistor divider and enabling the charge pump when the divided output droops below the comparators lower trip point (set by v ref ). when the charge pump is enabled, a 2-phase nonoverlapping clock controls the internal charge pump switches. flying capacitor c1 is charged to v in on phase one of the clock. on phase two of the clock, c1 is stacked in series with v in and connected to v out through an internal switch. this sequence of charging and discharging the flying capacitor occurs at a free running frequency of 700khz (typ) and continues until the divided output voltage reaches the upper trip point of the comparator. once the output is back in regulation, the charge pump is disabled. this method of bursting the charge pump on and off enables the ltc1517-3.3 to achieve high efficiency at extremely low output loads. capacitor selection for best performance, it is recommended that low esr capacitors be used for both c in and c out to reduce noise and ripple. the c in and c out capacitors should be either ceramic or tantalum and should be 3.3 m f or greater. ceramic capacitors will provide the smallest size for a given capacitance. if the input source impedance is very low (< 0.5 w ), c in may not be needed. ceramic capacitors are recommended for the flying capacitor c1 with values of 0.1 m f or 0.22 m f. smaller value flying capacitors may be used in low i out applications.
6 ltc1517-3.3 typical applicatio n s u low noise boosted 3.3v supply generating 3.3v and a negative supply 3.3 f 1517 ta05 123 4 5 0.1 f 0.1 f * ** 10k v out = 3.3v 4%
i out = 5ma (2v v in 4.4v)
i out = 10ma (2.5v v in 4.4v) ? out = ?.8v to 3v
? out = 0ma to 5ma v in
2v to 4.4v v in gnd ltc1517-3.3 v out c1 + c1 21.5k 470 w 3.3 f central semiconductor cmpsh-35 dual schottky
optional circuitry for maintaining v out with low
v out loads
q1, q2: 2n3904 *
** 3.3 f q2 q1 a 50mv/div
ac coupled v in = 2.7v
i out = 5ma 10 s/div 1517 ta04b b v out
2mv/div
ac coupled 3.3 f 1517 ta04a 123 4 5 0.1 f 3.3 f 1 f 3.3 f 470 w 470 w v out = 3.3v
i out = 8ma v ripple = 2mv p-p v in
2.7v to 4.4v v in gnd ltc1517-3.3 v out c1 + c1 q2 q1, q2: 2n3904 q1 a b
7 ltc1517-3.3 package descriptio n u dimensions in inches (millimeters) unless otherwise noted. s5 package 5-lead plastic sot-23 (ltc dwg # 05-08-1633) 0.95
(0.037)
ref 1.50 ?1.75
(0.059 ?0.069) 0.10 ?0.60
(0.004 ?0.024)
ref
0.35 ?0.50
(0.014 ?0.020)
five places (note 2) s5 sot-23 0797 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) 2.60 ?3.00
(0.102 ?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.
8 ltc1517-3.3 15173f lt/tp 0998 4k ? printed in usa ? linear technology corporation 1998 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com typical applicatio n u 3.3 f 75k 2-cell
nicd 1517-3.3 ta03 1 3 4 5 6 3 2 2 3 7 8 1.1m 3.9v trip 2 1 1 4 5 0.1 f logic low = backup mode ltc1517-3.3 ltc1540 lt1521-3.3 1 f main
supply
5v bat54 trickle charge
and ltc1517-3.3
i dd 1.5 f v out = 3.3v,
i out = 300ma
(i out = 8ma in
backup mode) 3.3 f siliconix
si2301ds 470k + low power battery backup supply with autoswitchover and no reverse current part number description comments ltc1514-x step-up/step-down switched-capacitor dc/dc converter with 3.3v or 5v output up to 50ma low battery comparator ltc1515 step-up/step-down switched-capacitor dc/dc converter with por fixed or adjustable output up to 50ma ltc1516 micropower regulated 5v charge pump dc/dc converter 20ma for v in 3 2v, 50ma for v in 3 3v ltc1517-5 micropower regulated 5v charge pump in a 5-pin sot-23 package i out up to 20ma ltc1522 micropower regulated 5v charge pump dc/dc converter same as ltc1517-5 with shutdown related parts
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