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LTC3200/LTC3200-5 1 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. the ltc ? 3200/LTC3200-5 are low noise, constant fre- quency switched capacitor voltage doublers. they pro- duce a regulated output voltage from a 2.7v to 4.5v input with up to 100ma of output current. low external parts count (one flying capacitor and two small bypass capaci- tors at v in and v out ) make the LTC3200/LTC3200-5 ideally suited for small, battery-powered applications. a new charge-pump architecture maintains constant switching frequency to zero load and reduces both output and input ripple. the LTC3200/LTC3200-5 have thermal shutdown capability and can survive a continuous short- circuit from v out to gnd. built-in soft-start circuitry prevents excessive inrush current during start-up. high switching frequency enables the use of small ceramic capacitors. a low current shutdown feature disconnects the load from v in and reduces quiescent current to <1 m a. the LTC3200 is available in an 8-pin msop package and the LTC3200-5 is available in a 6-pin sot-23. n white led backlighting n li-ion battery backup supplies n local 3v to 5v conversion n smart card readers n pcmcia local 5v supplies , ltc and lt are registered trademarks of linear technology corporation. n low noise constant frequency operation n output current: 100ma n fixed 5v 4% output (LTC3200-5) or adj n v in range: 2.7v to 4.5v n automatic soft-start reduces inrush current n 2mhz switching frequency n no inductors n i cc <1 m a in shutdown n available in 8-pin msop (LTC3200) and 6-pin sot-23 (LTC3200-5) packages applicatio s u features descriptio u typical applicatio u low noise, regulated charge pump dc/dc converters october 2000 final electrical specifications regulated 5v output from a 2.7v to 4.5v input output ripple voltage vs load current output current (ma) 0 output ripple (mv p-p ) 20 30 100 3200 ta02 10 0 25 50 75 40 c out = 2.2 f c out = 1 f v in = 3v c fly = 1 f t a = 25 c 1 LTC3200-5 2 3 6 5 4 v out 3200-5 ta01 1 m f 1 m f 1 m f gnd c + v in c shdn on off v in 2.7v to 4.5v v out = 5v 4% i out up to 40ma, v in 3 2.7v i out up to 100ma, v in 3 3.1v all capacitors = murata grm 39x5r105k6.3aj or taiyo yuden jmk107bj105ma
LTC3200/LTC3200-5 2 v in to gnd ................................................C 0.3v to 5.5v v out to gnd .............................................C 0.3v to 5.5v v fb , shdn to gnd ........................ C 0.3v to (v in + 0.3v) i out (note 2) ....................................................... 150ma order part number ms8 part marking t jmax = 150 c, q ja = 230 c/w consult factory for industrial and military grade parts. ltnv LTC3200ems8 absolute axi u rati gs w ww u package/order i for atio uu w (note 1) electrical characteristics the l denotes specifications which apply over the full operating temperature range. specifications are at t a = 25 c, v in = 3.6v, c fly = 1 m f, c in = 1 m f, c out = 1 m f unless otherwise noted. symbol parameter conditions min typ max units v in input voltage l 2.7 4.5 v v out output voltage 2.7v v in 4.5v, i out 40ma l 4.8 5 5.2 v 3.1v v in 4.5v, i out 100ma l 4.8 5 5.2 v i cc operating supply current i out = 0ma, shdn = v in l 3.5 8 ma i shdn shutdown current shdn = 0v, v out = 0v l 1 m a v fb fb voltage (LTC3200) l 1.217 1.268 1.319 v i fb fb input current (LTC3200) v fb = 1.4v l C50 50 na v r output ripple (LTC3200-5) v in = 3v, i out = 100ma 30 mv p-p h efficiency (LTC3200-5) v in = 3v, i out = 50ma 80 % f osc switching frequency 1 2 mhz v ih shdn input threshold l 1.3 v v il shdn input threshold l 0.4 v i ih shdn input current shdn = v in l C1 1 m a i il shdn input current shdn = 0v l C1 1 m a t on v out turn-on time v in = 3v, i out = 0ma, 10% to 90% 0.8 ms 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: based on long term current density limitations. note 3: the LTC3200e/LTC3200e-5 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. 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 order part number s6 part marking ltsh LTC3200es6-5 1 2 3 4 c + v in c pgnd 8 7 6 5 v out fb shdn sgnd top view ms8 package 8-lead plastic msop t jmax = 150 c, q ja = 200 c/w
LTC3200/LTC3200-5 3 typical perfor a ce characteristics uw output voltage vs supply voltage output voltage vs load current supply voltage (v) 2.7 output voltage (v) 5.15 5.10 5.05 5.00 4.95 4.90 4.85 3.0 3.3 3.6 3.9 3200 f01 4.2 4.5 c in = c out = c fly = 1 f i out = 20ma t a = 85 c t a = 25 c t a = 40 c load current (ma) 0 output voltage (v) 200 3200 g02 50 100 150 5.2 5.1 5.0 4.9 4.8 v in = 2.7v v in = 3v v in = 3.2v c in = c out = c fly = 1 f t a = 25 c supply voltage (v) 2.7 supply current (ma) 6 5 4 3 3.0 3.3 3.6 3.9 3200 g03 4.5 4.2 c in = c out = c fly = 1 f v shdn = v in t a = 85 c t a = 40 c t a = 25 c oscillator frequency (mhz) 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 supply voltage (v) 2.7 3.0 3.3 3.6 3.9 3200 g04 4.5 4.2 t a = 40 c t a = 25 c t a = 85 c supply voltage (v) 2.7 3.0 3.3 3.6 3.9 3200 g05 4.5 4.2 threshold voltage (v) 1.1 1.0 0.9 0.8 0.7 0.6 0.5 t a = 85 c t a = 25 c t a = 40 c supply voltage (v) 2.7 output current (ma) 250 200 150 100 3.0 3.3 3.6 3.9 3200 g07 4.5 4.2 c fly = 1 f t a = 25 c v out = 0v oscillator frequency vs supply voltage v shdn threshold voltage vs supply voltage efficiency vs load current no load supply current vs supply voltage short circuit current vs supply voltage load current (ma) efficiency (%) 100 90 80 70 60 50 40 30 1 10 100 3200 g06 c in = c out = c fly = 1 f t a = 25 c v in = 2.7v v in = 3.2v v in = 3.7v v in = 4.5v (LTC3200-5)
LTC3200/LTC3200-5 4 pi n fu n ctio n s uuu c + (pins 1/6): flying capacitor positive terminal. v in (pins 2/5): input supply voltage. v in should be bypassed with a 1 m f to 4.7 m f low esr ceramic capacitor. c C (pins 3/4): flying capacitor negative terminal. gnd (pins 4, 5/2): ground. should be tied to a ground plane for best performance. shdn (pins 6/3): active low shutdown input. a low on shdn disables the LTC3200/LTC3200-5. shdn must not be allowed to float. fb (pin 7): (LTC3200 only) feedback input pin. an output divider should be connected from v out to fb to program the output voltage. v out (pins 8/1): regulated output voltage. v out should be bypassed with a 1 m f to 4.7 m f low esr ceramic capaci- tor as close as possible to the pin for best performance. LTC3200/LTC3200-5 typical perfor a ce characteristics uw v out soft-start ramp output ripple load transient response (LTC3200-5) t a = 25 c v out (ac coupled) 20mv/div c out = 1 f 200ns/div v in = 3.3v i l = 100ma c out = 3.3 f c out = 10 f 32005 g09 i l 10ma to 90ma 50ma/div v out (ac coupled) 50mv/div 10 s/div v in = 3.3v c out = 1 f 32005 g10 v shdn 2v/div v out 1v/div 200 s/div v in = 3v 32005 g08
LTC3200/LTC3200-5 5 + v out v in shdn c + c 3200-5 bd charge pump 2mhz oscillator soft-start and switch control gnd 4 6 2 5 1 3 + v out v in shdn c + c 3200 bd charge pump 2mhz oscillator soft-start and switch control pgnd 3 1 4 sgnd 5 2 8 6 fb 7 LTC3200 LTC3200-5 si plified w block diagra s w
LTC3200/LTC3200-5 6 operatio u operation (refer to simplified block diagrams) the LTC3200/LTC3200-5 use a switched capacitor charge pump to boost v in to a regulated 5v 4% output voltage. regulation is achieved by sensing the output voltage through an internal resistor divider (LTC3200-5) and modulating the charge pump output current based on the error signal. a 2-phase nonoverlapping clock activates the charge pump switches. the flying capacitor is charged from v in on the first phase of the clock. on the second phase of the clock it is stacked in series with v in and connected to v out . this sequence of charging and dis- charging the flying capacitor continues at a free running frequency of 2mhz (typ). in shutdown mode all circuitry is turned off and the LTC3200/LTC3200-5 draw 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 approximately 0.8v. the LTC3200/LTC3200-5 is in shut- down 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. short-circuit/thermal protection the LTC3200/LTC3200-5 have built-in short-circuit current limiting as well as overtemperature protection. during short-circuit conditions, they will automatically limit their output current to approximately 225ma. at higher tempera- tures, or if the input voltage is high enough to cause exces- sive self heating on chip, thermal shutdown circuitry will shut down the charge pump once the junction temperature exceeds approximately 160 c. it will reenable the charge pump once the junction temperature drops back to approxi- mately 155 c. the LTC3200/LTC3200-5 will cycle in and out of thermal shutdown indefinitely without latch-up or damage until the short-circuit on v out is removed. soft-start the LTC3200/LTC3200-5 have built-in soft-start circuitry to prevent excessive current flow at v in during start-up. the soft-start time is preprogrammed to approximately 1ms, so the start-up current will be primarily dependent upon the output capacitor. the start-up input current can be calculated with the expression: ic v ms startup out out = 2 1 for example, with a 2.2 m f output capacitor the start-up input current of an LTC3200-5 will be approximately 22ma. if the output capacitor is 10 m f then the start-up input current will be about 100ma. programming the LTC3200 output voltage (fb pin) while the LTC3200-5 version has an internal resistive divider to program the output voltage, the programmable LTC3200 may be set to an arbitrary voltage via an external resistive divider. since it employs a voltage doubling charge pump, it is not possible to achieve output voltages greater than twice the available input voltage. figure 1 shows the required voltage divider connection. the voltage divider ratio is given by the expression: r r v v out 1 2 1 268 1 = . typical values for total voltage divider resistance can range from several k w s up to 1m w . 8 7 4 v out fb pgnd r1 32005 f01 c out r2 5 v out 1.268v 1 + r1 r2 () sgnd figure 1. programming the adjustable LTC3200 v in , v out capacitor selection the style and value of capacitors used with the LTC3200/ LTC3200-5 determine several important parameters such as regulator control loop stability, output ripple, charge pump strength and minimum start-up time. to reduce noise and ripple, it is recommended that low esr (< 0.1 w ) ceramic capacitors be used for both c in and c out . these capacitors should be 0.47 m f or greater.
LTC3200/LTC3200-5 7 tantalum and aluminum capacitors are not recommended because of their high esr. the value of c out directly controls the amount of output ripple for a given load current. increasing the size of c out will reduce the output ripple at the expense of higher minimum turn on time and higher start-up current. the peak-to-peak output ripple is approximately given by the expression: v i fc ripplep p out osc out - @ 2 where f osc is the LTC3200/LTC3200-5s oscillator fre- quency (typically 2mhz) and c out is the output charge storage capacitor. both the style and value of the output capacitor can signifi- cantly affect the stability of the LTC3200/LTC3200-5. as shown in the block diagrams, the LTC3200/LTC3200-5 use a linear control loop to adjust the strength of the charge pump to match the current required at the output. the error signal of this loop is stored directly on the output charge storage capacitor. the charge storage capacitor also serves to form the dominant pole for the control loop. to prevent ringing or instability on the LTC3200-5 it is important for the output capacitor to maintain at least 0.47 m f of capacitance over all conditions. on the adjustable LTC3200 the output capacitor should be at least 0.47 m f 5v/v out to account for the alternate gain factor. likewise excessive esr on the output capacitor will tend to degrade the loop stability of the LTC3200/LTC3200-5. the closed loop output resistance of the LTC3200-5 is designed to be 0.5 w . for a 100ma load current change, the output voltage will change by about 50mv. if the output capacitor has 0.3 w or more of esr, the closed loop frequency response will cease to roll off in a simple one pole fashion and poor load transient response or instabil- ity could result. ceramic capacitors typically have excep- tional esr performance and combined with a tight board layout should yield very good stability and load transient performance. as the value of c out controls the amount of output ripple, the value of c in controls the amount of ripple present at the input pin (v in ). the input current to the LTC3200/ LTC3200-5 will be relatively constant while the charge pump is on either the input charging phase or the output charging phase but will drop to zero during the clock nonoverlap times. since the nonoverlap time is small (~25ns), these missing notches will result in only a small perturbation on the input power supply line. note that a higher esr capacitor such as tantalum will have higher input noise due to the input current change times the esr. therefore ceramic capacitors are again recom- mended for their exceptional esr performance. further input noise reduction can be achieved by powering the LTC3200/LTC3200-5 through a very small series in- ductor as shown in figure 2. a 10nh inductor will reject the fast current notches, thereby presenting a nearly constant current load to the input power supply. for economy the 10nh inductor can be fabricated on the pc board with about 1cm (0.4") of pc board trace. operatio u figure 2. 10nh inductor used for additional input noise reduction LTC3200/ LTC3200-5 0.22 f 1 f v in gnd 10nh v in 32005 f02 flying capacitor selection warning: a polarized capacitor such as tantalum or aluminum should never be used for the flying capacitor since its voltage can reverse upon start-up of the LTC3200/ LTC3200-5. low esr ceramic capacitors should always be used for the flying capacitor. the flying capacitor controls the strength of the charge pump. in order to achieve the rated output current it is necessary to have at least 0.68 m f of capacitance for the flying capacitor. for very light load applications the flying capacitor may be reduced to save space or cost. the theoretical minimum
LTC3200/LTC3200-5 8 output resistance of a voltage doubling charge pump is given by: r vv ifc out min in out out osc fly () o@ 2 1 where f osc is the switching frequency (2mhz typ) and c fly is the value of the flying capacitor. the charge pump will typically be weaker than the theoretical limit due to additional switch resistance, however for very light load applications the above expression can be used as a guide- line in determining a starting capacitor value. ceramic capacitors ceramic capacitors of different materials lose their capaci- tance with higher temperature and voltage at different rates. for example, a capacitor made of x5r or 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 range. z5u and y5v capacitors may also have a very poor voltage coefficient causing them to lose 60% or more of their capacitance when the rated voltage is applied. therefore, when com- paring different capacitors it is often more appropriate to compare the amount of achievable capacitance for a given case size rather than discussing the specified capacitance value. for example, over rated voltage and temperature conditions, a 1 m f, 10v, y5v ceramic capacitor in an 0603 case may not provide any more capacitance than a 0.22 m f, 10v, x7r available in the same 0603 case. in fact for most LTC3200/LTC3200-5 applications these capaci- tors can be considered roughly equivalent . the capacitor manufacturers data sheet should be consulted to deter- mine what value of capacitor is needed to ensure the desired capacitance at all temperatures and voltages. below is a list of ceramic capacitor manufacturers and how to contact them: avx 1-(803)-448-1943 www.avxcorp.com kemet 1-(864)-963-6300 www.kemet.com murata 1-(800)-831-9172 www.murata.com taiyo-yuden 1-(800)-348-2496 www.t-yuden.com vishay 1-(800)-487-9437 www.vishay.com power efficiency the power efficiency ( h ) of the LTC3200/LTC3200-5 is similar to that of a linear regulator with an effective input voltage of twice the actual input voltage. this occurs because the input current for a voltage doubling charge pump is approximately twice the output current. in an ideal regulating voltage doubler the power efficiency would be given by: ho = = 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 LTC3200/LTC3200-5 are negligible and the expression above is valid. for example with v in = 3v, i out = 50ma and v out regulating to 5v the measured efficiency is 80% which is in close agreement with the theoretical 83.3% calculation. operation at v in > 5v LTC3200/LTC3200-5 will continue to operate with input voltages somewhat above 5v. however, because of its constant frequency nature, some charge due to internal switching will be coupled to v out causing a slight upward movement of the output voltage at very light loads. to avoid an output overvoltage problem with high v in , a moderate standing load current of 1ma will help the LTC3200/LTC3200-5 maintain exceptional line regula- tion. this can be achieved with a 5k resistor from v out to gnd. layout considerations due to its high switching frequency and the high transient currents produced by the LTC3200/LTC3200-5, 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 3 shows an example layout for the LTC3200-5. operatio u
LTC3200/LTC3200-5 9 operatio u thermal management for higher input voltages and maximum output current there can be substantial power dissipation in the LTC3200/ LTC3200-5. if the junction temperature increases above approximately 160 c the thermal shutdown circuitry will automatically deactivate the output. to reduce the maximum junction temperature, a good thermal connec- tion to the pc board is recommended. connecting the gnd pin (pins 4/5 for LTC3200, pin 2 for LTC3200-5) to a ground plane, and maintaining a solid ground plane under the device on two layers of the pc board can reduce the thermal resistance of the package and pc board considerably. derating power at higher temperatures to prevent an over-temperature condition in high power applications figure 4 should be used to determine the maximum combination of ambient temperature and power dissipation. the power dissipated in the LTC3200/LTC3200-5 should always fall under the line shown (i.e. within the safe region) for a given ambient temperature. the power dissipated in the LTC3200/LTC3200-5 is given by the expression: p d o (2v in C v out )i out this derating curve assumes a maximum thermal resistance, q ja , of 175 c/w for both the 6 pin sot-23 LTC3200-5 and the 8 pin msop adjustable LTC3200. this thermal resistances can be achieved from a printed circuit board layout with a solid ground plane on at least one layer and a good connection to the ground pins of the LTC3200/ LTC3200-5. operation outside of this curve will cause the junction temperature to exceed 125 c which may trigger the thermal shutdown circuitry and ultimately reduce the life of the device. figure 3. recommended layout LTC3200-5 v in v out gnd 32005 f03 shdn 1 m f 1 m f 1 m f figure 4. maximum power dissipation vs ambient temperature ambient temperature ( c) ?0 ?5 LTC3200 power dissipation (w) 050 25 75 100 3200 f04 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 unsafe region safe region q ja = 175 c/w t j = 125 c
LTC3200/LTC3200-5 10 package descriptio u dimensions in inches (millimeters) unless otherwise noted. ms8 package 8-lead plastic msop (ltc dwg # 05-08-1660) msop (ms8) 1098 * dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.006" (0.152mm) per side ** dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.006" (0.152mm) per side 0.021 0.006 (0.53 0.015) 0 ?6 typ seating plane 0.007 (0.18) 0.040 0.006 (1.02 0.15) 0.012 (0.30) ref 0.006 0.004 (0.15 0.102) 0.034 0.004 (0.86 0.102) 0.0256 (0.65) bsc 12 3 4 0.193 0.006 (4.90 0.15) 8 7 6 5 0.118 0.004* (3.00 0.102) 0.118 0.004** (3.00 0.102)
LTC3200/LTC3200-5 11 package descriptio u dimensions in inches (millimeters) unless otherwise noted. s6 package 6-lead plastic sot-23 (ltc dwg # 05-08-1634) 1.50 ?1.75 (0.059 ?0.069) 0.35 ?0.55 (0.014 ?0.022) s6 sot-23 0898 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) 0.35 ?0.50 (0.014 ?0.020) six places (note 2) 0.90 ?1.45 (0.035 ?0.057) 0.90 ?1.30 (0.035 ?0.051) 0.00 ?0.15 (0.00 ?0.006) 0.95 (0.037) ref 2.80 ?3.00 (0.110 ?0.118) (note 3) 1.90 (0.074) ref
LTC3200/LTC3200-5 12 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com ? linear technology corporation 2000 32005i lt/lcg 1000 4k ? printed in usa related parts part number description comments ltc1682/-3.3/-5 doubler charge pumps with low noise ldo ms8 and so-8 packages , i out = 80ma, output noise = 60 m v rms ltc1751/-3.3/-5 doubler charge pumps v out = 5v at 100ma; v out = 3.3v at 80ma; adj; msop packages ltc1754-3.3/-5 doubler charge pumps with shutdown sot-23 package; i q = 13 m a; i out = 50ma ltc1928-5 doubler charge pump with low noise ldo sot-23 output noise = 60 m v rms ; v out = 5v; v in = 2.7v to 4v 3v to 4.4v li-ion battery c c + v in 46 v out LTC3200-5 gnd shdn 1 2 5 1 f 3 100 1 f 1 f 100 100 3200-5 ta03 100 100 drive up to 5 leds on off v shdn (apply pwm waveform for adjustable brightness control) t lithium-ion battery to 5v white or blue led driver typical applicatio s u white or blue led driver with led current control 1 f LTC3200 c + c v out fb on off pgnd v in shdn 8 13 7 4 sgnd 5 2 6 82 32005 ta04 1 f 82 up to 6 leds 82 82 82 82 3v to 4.4v li-ion battery 1 f v shdn (apply pwm waveform for adjustable brightness control) t

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