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ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 1 3204fa fea tures descriptio u typical applica tio u the ltc ? 3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 are low noise, constant frequency (1.2mhz) switched ca - pacitor voltage doublers. the ltc3204-3.3/ltc3204b-3.3 can produce a regulated output voltage of 3.3v from a minimum input voltage of 1.8v (2 alkaline cells) whereas the ltc3204-5/ltc3204b-5 can produce 5v from a minimum of 2.7v (li-ion battery) input. ltc3204-3.3/ltc3204-5 feature automatic burst mode ? operation at light loads to maintain low supply current whereas ltc3204b-3.3/ltc3204b-5 feature constant frequency operation at any load. built-in soft-start circuitry prevents excessive inrush current during start-up. thermal shutdown and current-limit circuitry allow the parts to survive a continuous short-circuit from v out to gnd. high switching frequency minimizes overall solution footprint by allowing the use of tiny ceramic capaci - tors. in shutdown, the load is disconnected from the input and the quiescent current is reduced to <1a. the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 are available in a low pro?le (0.75mm) 6-lead 2mm 2mm dfn package. low noise regulated charge pump in 2 2 dfn fixed 3.3v or 5v outputs v in range: 1.8v to 4.5v (ltc3204-3.3/ltc3204b-3.3) 2.7v to 5.5v (ltc3204-5/ltc3204b-5) output current: up to 150ma (ltc3204-5/ltc3204b-5) up to 50ma (ltc3204-3.3/ltc3204b-3.3) automatic burst mode ? operation with i q = 48a (ltc3204-3.3/ltc3204-5) constant frequency operation at all loads (ltc3204b-3.3/ltc3204b-5) low noise constant frequency (1.2mhz) operation* built-in soft-start reduces inrush current shutdown disconnects load from input shutdown current <1a short-circuit/thermal protection available in low pro?le 6-lead dfn package 2 aa cell to 3.3v li-ion to 5v usb on-the-go devices white led drivers handheld devices output ripple vs load current burst mode is a registered trademark of linear technology corporation. *protected by u.s. patents including 6411531 . applica tio s u , ltc and lt are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. off on v in gnd shdn v out c C c + ltc3204-5/ ltc3204b-5 2.2 f 2.2 f 2.2 f 5v 2.7v to 5.5v 3204 t a01a 1, 7 2 3 4 5 6 output current (ma) 0 0 output ripple (mvp-p) 5 10 15 20 30 25 50 75 100 3204 ta01b 125 150 25 output capacitance = 2.2 f v in = 3.6v ltc3204b-5 ltc3204-5
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 2 3204fa absolute axi u r at i g s w w w u for a tio package/order i u u w electrical characteristics symbol parameter conditions min typ max units v in input voltage range (ltc3204-3.3/ltc3204b-3.3) 1.8 4.5 v (ltc3204-5/ltc3204b-5) 2.7 5.5 v v out output voltage range 1.8v < v in < 4.5v, i out < 40ma 1.9v < v in < 4.5v, i out < 50ma (ltc3204-3.3/ltc3204b-3.3) 3.168 3.3 3.432 v 2.7v < v in < 5.5v, i out < 65ma 3.1v < v in < 5.5v, i out < 150ma (ltc3204-5/ltc3204b-5) 4.8 5 5.2 v i in no load input current i out = 0 (ltc3204-3.3) 48 a i out = 0 (ltc3204-5) 60 a i out = 0 (ltc3204b-3.3) 1.25 ma i out = 0 (ltc3204b-5) 3.6 ma i ? s ? h ? d ? n shutdown current ? s ? h ? d ? n = 0v, v out = 0v 1 a i burst burst mode threshold (ltc3204-3.3) 15 ma (ltc3204-5) 20 ma v r output ripple i out = 100ma 20 mv p-p ef?ciency v in = 3v, i out = 100ma (ltc3204-5/ltc3204b-5) 82 % f osc switching frequency 0.6 1.2 1.8 mhz v ih ? s ? h ? d ? n input threshold 1.3 v v il ? s ? h ? d ? n input threshold 0.4 v i ih ? s ? h ? d ? n input current C1 1 a i il ? s ? h ? d ? n input current ? s ? h ? d ? n = 0v C1 1 a r ol effective open-loop output v in = 1.8v, v out = 3v (ltc3204-3.3/ltc3204b-3.3) 7 resistance (note 3) v in = 2.7v, v out = 4.5v (ltc3204-5/ltc3204b-5) 6 i lim output current limit v out = ov 300 ma t ss soft-start time from the rising edge of ? s ? h ? d ? n to 90% of v out 0.75 ms v in to gnd ................................................... C 0.3v to 6v v out to gnd ............................................. C 0.3v to 5.5v ? s ? h ? d ? n to gnd ............................................... C 0.3v to 6v v out short-circuit duration ............................. inde?nite operating temperature range (note 2) ... C 40c to 85c storage temperature range .................. C 65c to 125c maximum junction temperature .......................... 125c (note 1) the denotes the speci?cations which apply over the full operating temperature range. speci?cations are at t a = 25c, v in = 2.4v (ltc3204-3.3/ltc3204b-3.3) or 3.6v (ltc3204-5/ltc3204b-5), s ? h ? d ? n = v in , c fly = 2.2f, c in = 2.2f, c out = 2.2f unless otherwise noted. note 1: absolute maximum ratings are those beyond which the life of a device may be impaired. note 2 : the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 are guaranteed to meet performance speci?cations from 0c to 70c. speci?cations over the C 40c to 85c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: r ol (2v in C v out )/i out consult ltc marketing for parts speci?ed with wider operating temperature ranges. order part number dc part marking lbjv lbnk lbvf lbvg ltc3204edc-3.3 ltc3204edc-5 ltc3204bedc-3.3 ltc3204bedc-5 t jmax = 125c, ja = 80c/w exposed pad is gnd (pin 7) must be soldered to pcb top view dc p ackage 6-lead (2mm 2mm) plastic dfn 4 5 6 7 3 2 1 gnd v in v out shdn c C c +
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 3 3204fa typical perfor u w ce characteristics a tempera ture ( c) C50 150 3204 g05 0 50 100 tempera ture ( c) C50 150 0 50 100 3204 g04 threshold volt age (v) 0.7 0.8 0.6 0.5 0.9 shdn threshold lo-to-hi (v) 0.7 0.8 0.6 0.5 0.9 shdn threshold hi-to-lo (v) 0.6 0.7 0.5 0.4 0.8 supply vol t age (v) 1.5 frequency (mhz) 1.50 1.25 1.00 0.75 0.50 0.25 0 2.0 2.5 3.0 3.5 4.0 4.5 3204 g01 suppl y volt age (v ) 1.5 2.0 2.5 3.0 3.5 4.0 4.5 3204 g03 tempera ture ( c) C50 frequency (mhz) 1.4 1.3 1.2 1.1 1.0 0.9 0.8 C20 10 40 70 100 130 3204 g02 suppl y volt age (v ) shor t -circuit current (ma ) 350 300 250 200 150 100 50 0 3204 g06 1.5 2.0 2.5 3.0 3.5 4.0 4.5 device cycles in and out of thermal shutdown v in = 4.5v high-to-low threshold low -to-high threshol d v in = 3.2v v in = 3.2v v in = 1.8v v in = 1.8v v in = 2.4v v in = 1.8v v in = 2.4v v in = 2.4v oscillator frequency vs supply voltage oscillator frequency vs temperature ? s ? h ? d ? n threshold voltage vs supply voltage short-circuit current vs supply (t a = 25c, c fly = c in = c out = 2.2f unless otherwise speci?ed) ? s ? h ? d ? n lo-to-hi threshold vs temperature ? s ? h ? d ? n hi-to-lo threshold vs temperature
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 4 3204fa suppl y volt age (v ) 1.8 efficiency (%) 100 90 80 70 60 50 40 30 20 10 0 2.2 2.6 2.8 2.0 2.4 3.0 3.2 tempera ture ( c) C50 0 50 100 6 7 5 9 3204 g09 v in = 1.8v v out = 3v 3204 g12 3204 g14 3204 g13 3204 g15 3204 g07 supply volt age (v ) load current (ma) 400 350 300 250 200 150 100 50 0 3204 g08 1.5 2.0 2.5 3.0 3.5 8 i out = 1ma theoretical max i out = 30ma load current (ma) 0 output volt age (v) 3.35 3.30 3.25 3.20 3.15 3.10 3.05 100 200 300 400 500 v in = 1.8v v in = 2.4v v in = 3.2v v out = 3.168v t a = 25 c t a = 90 c t a = C 4 5 c supply voltage (v) 1.8 44 no-load input current ( a) no-load input current (ma) 46 50 52 54 64 58 2.2 2.6 2.8 3204 g10 48 60 62 56 0 0.2 0.6 0.8 1.0 2.0 1.4 0.4 1.6 1.8 1.2 2 2.4 3 3.2 ltc3204b-3.3 ltc3204-3.3 load current (ma) 0.01 0.1 excess input current (ma) 1 0.01 0.1 1 1 0 100 3204 g1 1 10 1000 ltc3204b-3.3 (non-burst mode operation) ltc3204-3.3 (burst mode operation) v in = 2.4v v out soft-start response output ripple load transient response no-load input current vs supply voltage extra input current vs load current (i in -2i load ) effective open-loop output resistance vs temperature (t a = 25c, c fly = c in = c out = 2.2f unless otherwise speci?ed) load regulation output load capability at 4% below regulation (ltc3204-3.3/ltc3204b-3.3 only) v out 20mv/div (ac coupled) i out 50ma 30ma 10s/div v out 2v/div ? s ? h ? d ? n 2v/div 500s/div v out 20mv/div (ac coupled) 500ns/div v in = 2.4v i load = 50ma v in = 2.4v i load = 50ma v in = 2.4v i out = 30ma to 50ma step 3204 g13 3204 g14 3204 g15 ef?ciency vs supply voltage typical perfor a ce char ac teristics u w
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 5 3204fa 2.7 4.5 3.0 3.3 3.6 3.9 4.2 3204 g18 3204 g21 3204 g23 3204 g22 3204 g24 3204 g16 3204 g17 supply vol t age (v ) 2.7 output load (ma) 3.9 3.0 3.3 3.6 4.2 500 450 400 350 300 250 200 150 100 50 0 tempera ture ( c) 100 0 5 0 v in = 2.7v v out = 4.5v v out = 4.8v load current (ma) 0 5.20 5.10 5.00 4.90 4.80 4.70 4.60 4.50 300 100 200 400 500 output vol t age (v) v in = 4.2v v in = 2.7v v in = 3.6v suppl y volt age (v ) efficiency (%) 100 90 80 70 60 50 40 30 20 10 0 i out = 1ma theoretical max i out = 10ma i out = 100ma C50 8 7 6 5 4 t a = 25 c t a = 90 c t a = C 4 5 c supply voltage (v) 2.7 50 no-load input current ( a) no-load input current (ma) 54 58 62 3 3.3 3.6 3.9 3204 g19 4.2 66 70 52 56 60 64 68 0 0.8 1.6 2.4 3.2 4.0 0.4 1.2 2.0 2.8 3.6 4.5 ltc3204b-5 ltc3204-5 load current (ma) 0.01 0.1 excess input current (ma) 1 0.01 0.1 1 1 0 100 3204 g2 0 10 1000 ltc3204b-5 (n0n-burst mode operation) ltc3204-5 (burst-mode operation) v in = 3.6v load regulation output load capability at 4% below regulation effective open-loop output resistance vs temperature v out soft-start output ripple load transient response no-load input current vs supply voltage ef?ciency vs supply voltage extra input current vs load current (i in -2i load ) (t a = 25c, c fly = c in = c out = 2.2f unless otherwise speci?ed) (ltc3204-5/ltc3204b-5 only) v out 50mv/div (ac coupled) i out 100ma 60ma 10s/div v out 2v/div ? s ? h ? d ? n 5v/div 500s/div v out 20mv/div (ac coupled) 500ns/div v in = 3.6v i out = 100ma v in = 3.6v i out = 100ma v in = 3.6v i out = 60ma to 100ma step typical perfor a ce char ac teristics u w
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 6 3204fa gnd (pin 1, 7): ground. these pins should be tied to a ground plane for best performance. the exposed pad must be soldered to pcb ground to provide electrical contact and optimum thermal performance. v in (pin 2): input supply voltage. v in should be bypassed with a 1f to 4.7f low esr ceramic capacitor. v out (pin 3): regulated output voltage. v out should be bypassed with a low esr ceramic capacitor providing at least 2f of capacitance as close to the pin as possible for best performance. c + (pin 4): flying capacitor positive terminal. c C (pin 5): flying capacitor negative terminal. ? s ? h ? d ? n (pin 6): active low shutdown input. a low on ? s ? h ? d ? n disables the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ ltc3204b-5. this pin must not be allowed to ?oat. C + v out v in shdn c + c C 3204 bd charge pump 1.2mhz oscilla tor soft- st ar t and switch control gnd 5 4 1, 7 2 3 6 u u u pi fu ctio s block diagra w
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 7 3204fa the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 use 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 modulating the charge pump output current based on the error signal. a 2-phase nonoverlapping clock activates the charge pump switches. the ?ying capacitor is charged from v in on the ?rst 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 discharging the ?ying capacitor continues at a free running frequency of 1.2mhz (typ). shutdown mode in shutdown mode, all circuitry is turned off and the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 draws only leakage current from the v in supply. further - more, v out is disconnected from v in . the ? s ? h ? d ? n pin is a cmos input with a threshold voltage of approximately 0.7v. the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 are in shutdown when a logic low is applied to the ? s ? h ? d ? n pin. since the ? s ? h ? d ? n pin is a very high impedance cmos input, it should never be allowed to ?oat. to ensure that its state is de?ned, it must always be driven with a valid logic level. since the output voltages of these devices can go above the input voltage, special circuitry is required to control the internal logic. detection logic will draw an input current of 5a when the devices are in shutdown. however, this current will be eliminated if the output voltage (v out ) is less than approximately 0.8v. burst mode operation the ltc3204-3.3/ltc3204-5 provide automatic burst mode operation to reduce supply current at light loads. burst mode operation is initiated if the output load current falls below an internally programmed threshold. once (refer to the block diagram) burst mode operation is initiated, the part shuts down the internal oscillator to reduce the switching losses and goes into a low current state. this state is referred to as the sleep state in which the ic consumes only about 40a from the input. when the output voltage droops enough to overcome the burst comparator hysteresis, the part wakes up and commences normal ?xed frequency opera - tion. the output capacitor recharges and causes the part to reenter the sleep state if the output load still remains less than the burst mode threshold. this burst mode threshold varies with v in , v out and the choice of output storage capacitor. soft-start the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 have built-in soft-start circuitry to prevent excessive current ?ow during start-up. the soft-start is achieved by charging an internal capacitor with a very weak current source. the voltage on this capacitor, in turn, slowly ramps the amount of current available to the output storage capacitor from zero to a value of 300ma over a period of approximately 0.75ms. the soft-start circuit is reset in the event of a commanded shutdown or thermal shutdown. short-circuit/thermal protection the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 have built-in short-circuit current limit as well as over-tem - perature protection. during a short-circuit condition, they will automatically limit their output current to approximately 300ma. at higher temperatures, or if the input voltage is high enough to cause excessive self-heating of the part, the thermal shutdown circuitry will shutdown the charge pump once the junction temperature exceeds approximately 160c. it will enable the charge pump once the junction temperature drops back to approximately 150c. the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 will cycle in and out of thermal shutdown inde?nitely without latchup or damage until the short-circuit condition on v out is removed. operatio u
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 8 3204fa power ef?ciency the power ef?ciency ( ) of the ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-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 ef?ciency would be given by: = = = p p v i v i v v out in out out in out out in ? ? 2 2 at moderate to high output power, the switching losses and the quiescent current of the ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 are negligible and the expres - sion above is valid. for example, with v in = 3v, i out = 100ma and v out regulating to 5v, the measured ef?ciency is 81.8% which is in close agreement with the theoretical 83.3% calculation. maximum available output current for the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ ltc3204b-5,the maximum available output current and voltage can be calculated from the effective open-loop output resistance, r ol , and the effective input voltage, 2v in(min) . (f osc ), value of the ?ying capacitor (c fly ), the nonoverlap time, the internal switch resistances (r s ), and the esr of the external capacitors. a ?rst order approximation for r ol is given below: r r f c ol s osc fly ? + 2 1 ? typical r ol values as a function of temperature are shown in figure 2. figure 1. equivalent open-loop circuit from fig. 1, the available current is given by: i v v r out in out ol = 2 C effective open loop output resistance (r ol ) the effective open loop output resistance (r ol ) of a charge pump is a very important parameter which determines the strength of the charge pump. the value of this parameter depends on many factors such as the oscillator frequency figure 2. typical r ol vs temperature v in , v out capacitor selection the style and value of capacitors used with the ltc3204-3.3/ ltc3204-5/ltc3204b-3.3/ltc3204b-5 determine several important parameters such as regulator control loop sta - bility, output ripple, charge pump strength and minimum start-up time. to reduce noise and ripple, it is recommended that low esr (<0.1 ) ceramic capacitors be used for both c in and c out . these capacitors should be 1f or greater. 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. the peak-to-peak output ripple is approximately given by the expression: v i f c ripple p p out osc out ( ) ? ? ? 2 + C r ol i out v out 2v in 3204 f01 + C s=1 to 4 applica tio s i for a tio w u u u 3204 f02 temperature ( c) 100 0 5 0 effective open-loop output resistance ( ? ) v in = 2.7v v out = 4.5v C50 8 7 6 5 4
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 9 3204fa where f osc is the oscillator frequency (typically 1.2mhz) and c out is the value of output charge storage capacitor. also, the value and style of the output capacitor can signi? - cantly affect the stability of the ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5. as shown in the block diagram, the ltc3204-3.3/ltc3204-5/ltc3204b- 3.3/ltc3204b-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 storage capacitor. this out - put capacitor also serves to form the dominant pole of the control loop. to prevent ringing or instability on the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5, it is important to maintain at least 1f of capacitance over all conditions. excessive esr on the output capacitor can degrade the loop stability of the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ ltc3204b-5. the closed loop output resistance of the ltc3204-5 is designed to be 0.5 . for a 100ma load current change, the output voltage will change by about 50mv. if the output capacitor has 0.5 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 instability could result. ceramic capacitors typically have exceptional esr performance and combined with a good 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 ltc3204-3.3/ ltc3204-5/ltc3204b-3.3/ltc3204b-5 will be relatively constant during the input charging phase or the output charging phase but will drop to zero during the 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 voltage drop in the esr. therefore, ceramic capacitors are again recommended for their exceptional esr performance. further input noise reduction can be achieved by powering the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5 through a very small series inductor as shown in figure 3. 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. figure 3. 10nh inductor used for additional input noise reduction flying capacitor selection warning: a polarized capacitor such as tantalum or aluminum should never be used for the ?ying capaci - tor since its voltage can reverse upon start-up of the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5. low esr ceramic capacitors should always be used for the ?ying capacitor. the ?ying capacitor controls the strength of the charge pump. in order to achieve the rated output current, it is necessary to have at least 1f of capacitance for the ?y - ing capacitor. for very light load applications, the ?ying capacitor may be reduced to save space or cost. from the ?rst order approxi - mation of r ol in the section effective open-loop output resistance, the theoretical minimum output resistance of a voltage doubling charge pump can be expressed by the following equation: r v v i f c l m in in out out osc fly 0 2 1 ( ) C ? = ? where f osc is the switching frequency (1.2mhz) and c fly is the value of the ?ying 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. ltc3204-3.3/ ltc3204-5 0.22f 2.2f v in gnd 1cm of wire 10nh v in 1 2 32005 f03 applica tio s i for a tio w u u u
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 10 3204fa c out 0603 c in 0603 c fl y 0603 gnd v out v in 3204 f04 shdn c + c C 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 40c to 85c whereas a z5u or y5v style capacitor will lose considerable capacitance over that range. z5u and y5v capacitors may also have a poor voltage coef?cient causing them to lose 60% or more of their capacitance when the rated voltage is applied. therefore when comparing different capacitors, it is often more appropriate to compare the amount of achievable capacitance for a given case size rather than discussing the speci?ed capacitance value. for example, over rated voltage and temperature conditions, a 1f 10v y5v ceramic capacitor in a 0603 case may not provide any more capacitance than a 0.22f 10v x7r capacitor avail - able in the same 0603 case. in fact, for most ltc3204-3.3/ ltc3204-5/ltc3204b-3.3/ltc3204b-5 applications, these capacitors can be considered roughly equivalent. the capacitor manufacturers data sheet should be consulted to ensure the desired capacitance at all temperatures and voltages. below is a list of ceramic capacitor manufacturers and how to contact them: avx www.avxcorp.com kemet www.kemet.com murata www.murata.com taiyo yuden www.t-yuden.com vishay www.vishay.com tdk www.component.tdk.com layout considerations due to the high switching frequency and high transient currents produced by ltc3204-3.3/ltc3204-5/ltc3204b- 3.3/ltc3204b-5, careful board layout is necessary for optimum performance. a true ground plane and short connections to all the external capacitors will improve per - formance and ensure proper regulation under all conditions. figure 4 shows an example layout for the ltc3204-3.3/ ltc3204-5/ltc3204b-3.3/ltc3204b-5. thermal management for higher input voltages and maximum output cur - rent, there can be substantial power dissipation in the ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ltc3204b-5. if the junction temperature increases above approximately 160c, 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 1) and the exposed pad of the dfn package (pin 7) to a 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 high temperatures to prevent an overtemperature condition in high power applications, figure 5 should be used to determine the maximum combination of ambient temperature and power dissipation. the power dissipated in the ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 should always fall under the line shown for a given ambient temperature. the power dissipation in the ltc3204-3.3/ ltc3204-5/ltc3204b-3.3/ ltc3204b-5 is given by the expression: p v v i d i n out out = ( C )? 2 this derating curve assumes a maximum thermal resis - tance, ja , of 80c/w for the 2mm 2mm dfn package. figure 4. recommended layout applica tio s i for a tio w u u u
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 11 3204fa package descriptio u this can be achieved from a printed circuit board layout with a solid ground plane and a good connection to the ground pins of ltc3204-3.3/ltc3204-5/ltc3204b-3.3/ ltc3204b-5 and the exposed pad of the dfn package. figure 5. maximum power dissipation vs ambient temperature operation out of this curve will cause the junction tem - perature to exceed 160c which may trigger the thermal shutdown. ambient temperature (c) power dissipation (w) 3204 g05 3.0 2.5 2.0 1.5 1.0 0.5 0 C50 0 50 75 C25 25 100 125 150 dc package 6-lead plastic dfn (2mm 2mm) (reference ltc dwg # 05-08-1703) 2.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (wccd-2) 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 0.38 0.05 bottom viewexposed pad 0.56 0.05 (2 sides) 0.75 0.05 r = 0.115 typ 1.37 0.05 (2 sides) 1 3 6 4 pin 1 bar top mark (see note 6) 0.200 ref 0.00 C 0.05 (dc6) dfn 1103 0.25 0.05 1.42 0.05 (2 sides) recommended solder pad pitch and dimensions 0.61 0.05 (2 sides) 1.15 0.05 0.675 0.05 2.50 0.05 package outline 0.25 0.05 0.50 bsc 0.50 bsc pin 1 chamfer of exposed pad 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. applica tio s i for a tio w u u u
ltc3204-3.3/ltc3204-5/ ltc3204b-3.3/ltc3204b-5 12 3204fa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com ? linear technology corporation 2004 lt/lt 0605 ? printed in usa rela ted parts 2 5 4 ltc3204-5 2.2 f 2.2 f 2.2 f 6 3 1, 7 32005 ta05 v out 5v 4% c C c + v in v out gnd shdn regulated 3.3v output lithium-ion battery to 5v white or blue led driver usb port to regulated 5v power supply part number description comments ltc1751-3.3/ 100ma, 800khz regulated doubler v in : 2v to 5v, v out(max) = 3.3v/5v, i q = 20a, ltc1751-5 i sd <2a, ms8 package ltc1983-3/ 100ma, 900khz regulated inverter v in : 3.3v to 5.5v, v out(max) = C3v/C5v, i q = 25a, ltc1983-5 i sd <1a, thinsot package ltc3200-5 100ma, 2mhz low noise, doubler/ v in : 2.7v to 4.5v, v out(max) = 5v, i q = 3.5ma, white led driver i sd <1a, thinsot package ltc3202 125ma, 1.5mhz low noise, fractional v in : 2.7v to 4.5v, v out(max) = 5.5v, i q = 2.5ma, white led driver i sd <1a, dfn, ms packages typical applica tio s u 3v to 4.4v li-ion ba tter y c C c + v in 5 4 v out ltc3204-5/ ltc3204b-5 gnd shdn 3 1, 7 2 2.2 f 6 2.2 f 2.2 f 3200-5 ta03 drive up to 5 leds on off v shdn (apply pwm waveform for adjustable brightness control) t 100 ? 100 ? 100 ? 100 ? 100 ? off on v in gnd shdn v out v out 3.3v c C c + ltc3204-3.3/ ltc3204b-3.3 2.2 f 2.2 f 2.2 f v in 1.8v to 4.5v 3204 t a02 1, 7 2 3 4 5 6

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