ltc4411 1 4411fa ltc4411 schottky diode constant i on constant r on constant v on v fwd forward voltage (v) ltc4411 fo1b slope 1/r on slope 1/r fwd i oc i max i fwd current (a) in gnd ctl out stat ltc4411 wall adapter input to load 4.7 f status output is low when wall adapter is supplying load current battery cell(s) 470k 4411 f01 v cc typical applicatio u applicatio s u descriptio u features , ltc and lt are registered trademarks of linear technology corporation. thinsot and powerpath are trademarks of linear technology corporation. all other trademarks are the property of their respective owners. low loss replacement for powerpath tm oring diodes small regulated forward voltage (28mv) 2.6a maximum forward current low forward on resistance (140m ? max) low reverse leakage current (<1 a) 2.6v to 5.5v operating range internal current limit protection internal thermal protection no external active components pin-compatible monolithic replacement for the ltc4412 low quiescent current (40 a) low-profile (1mm) 5-lead sot-23 package 2.6a low loss ideal diode in thinsot tm the ltc ? 4411 is an ideal diode ic, capable of supplying up to 2.6a from an input voltage between 2.6v and 5.5v. the ltc4411 is housed in a 5-lead 1mm profile sot-23 package. the ltc4411 contains a 140m ? p-channel mosfet con- necting in to out. during normal forward operation, the drop across the mosfet is regulated to as low as 28mv. quiescent current is less than 40 a for load currents up to 100ma. if the output voltage exceeds the input voltage, the mosfet is turned off and less than 1 a of reverse current flows from out to in. maximum forward current is limited to a constant 2.6a (typical) and internal thermal limiting cir- cuits protect the part during fault conditions. an open-drain stat pin indicates conduction status. the stat pin can be used to drive an auxiliary p-channel mosfet power switch connecting an alternate power source when the ltc4411 is not conducting forward current. an active-high control pin turns off the ltc4411 and reduces current consumption to less than 25 a. when shut off, the ltc4411 indicates this condition with a low voltage on the status signal. figure 1. automatic switchover of load between a battery and a wall adapter cellular phones handheld computers digital cameras usb peripherals uninterrupted supplies logic controlled power switch ltc4411 vs schottky diode forward voltage characteristics
2 ltc4411 4411fa in, out, stat, ctl voltage .......................... C0.3 to 6v operating ambient temperature range (note 2) ...............................................C40 c to 85 c operating junction temperature (note 3) .............................................C40 c to 125 c storage temperature range ..................C65 c to 150 c lead temperature (soldering, 10 sec).................. 300 c continuous power dissipation (derate 10mw/ c above 70 c) ...................... 500mw order part number s5 part marking t jmax = 125 c, ja = 250 c/w (note 3) ltaen ltc4411es5 absolute axi u rati gs w ww u package/order i for atio uu w (note 1) consult ltc marketing for parts specified with wider operating temperature ranges. electrical characteristics 5 out 4 stat in 1 top view s5 package 5-lead plastic sot-23 gnd 2 ctl 3 the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. (note 6) symbol parameter conditions min typ max units v in , v out operating supply range 2.6 5.5 v i qf quiescent current in forward regulation v in = 3.6v, i load = 100ma 40 a (note 4) i q(off) quiescent current in shutdown v in = 3.6v, v stat = 0v, v ctl > v ih 22 25 a i qrin quiescent current while in reverse v in = 3.6v 1.3 1.8 2.3 a turn-off. current drawn from v in v out = 3.7v i qrout quiescent current while in reverse v in = 3.6v 14 17 23 a turn-off. current drawn from v out v out = 3.7v i leak v in current when v out supplies power v in = 0v, v out = 5.5v C1 1 a v fwd forward turn-on voltage (v in C v out )v in = 3.6v 81728 mv Cv rto reverse turn-off voltage (v out C v in )v in = 3.6v C 4 5 14 mv r fwd forward on resistance, ? (v in -v out )/ ? (i load )v in = 3.6v, 100ma < i load < 500ma 100 140 m ? r on on resistance in constant r on mode v in = 3.6v, i load = 1000ma 140 245 m ? uvlo undervoltage lockout v in rising, 0 c < t a < 85 c 2.5 v v in rising 2.6 v v in falling 1.6 v stat output i s(snk) stat pin sink current v in = 3.6v, v out > v in + v rto , 7 11 18 a v ctl > v th + v hyst i s(off) stat pin off current v in = 3.6v, v out < v in C v fwd ,C1 1 a v ctl < v th C v hyst t s(on) stat pin turn-on time 1.2 1.4 s t s(off) stat pin turn-off time 1.1 1.25 s ctl input v th ctl input threshold voltage v th = (v il + v ih )/2 390 460 530 mv v hyst ctl input hysteresis v hyst = (v ih C v il )90mv i ctl ctl input pull-down current v out < v in = 3.6v, v ctl = 1.5v 2 3.5 6 a short-circuit response i oc current limit v in = 3.6v (note 5) 1.8 2.6 a i qoc quiescent current while in v in = 3.6v, i out = 1.8a 575 1100 a overcurrent operation
ltc4411 3 4411fa measured thermal resistance (2-layer board*) copper area board thermal resistance topside backside area junction-to-ambient 2500mm 2 2500mm 2 2500mm 2 125 c/w 1000mm 2 2500mm 2 2500mm 2 125 c/w 225mm 2 2500mm 2 2500mm 2 130 c/w 100mm 2 2500mm 2 2500mm 2 135 c/w 50mm 2 2500mm 2 2500mm 2 150 c/w *each layer uses one ounce copper load current (a) 0.5 1.5 2.5 1.0 2.0 3.0 4411 g01 quiescent current ( a) 0 load current (a) load current (a) 0.5 1.5 2.5 1.0 2.0 3.0 0 t a = C40 c t a = 0 c t a = 40 c t a = 80 c t a = 120 c forward voltage (v) 4411 g02 0 resistance ( ? ) 0.5 1.0 1.5 2.0 4411 g03 1000 0.5 0.4 0.3 0.2 0.1 0.15 0.10 0.30 0.25 0.20 0.05 0 100 10 0 t a = C40 c t a = 0 c t a = 40 c t a = 80 c t a = 120 c t a = C40 c t a = 0 c t a = 40 c t a = 80 c t a = 120 c electrical characteristics the denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. (note 6) typical perfor a ce characteristics uw typical i qf vs i load at v in = 3.6v v fwd vs i load at v in = 3.6v note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: the ltc4411e is guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C40 c to 85 c ambient operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: t j is calculated from the ambient temperature t a and power dissipation p d according to the following formula: t j = t a + (p d ? 150 c/w) the following table lists thermal resistance for several different board sizes and copper areas. all measurements were taken in still air on 3/32" fr-4 board with the device mounted on topside. note 4: quiescent current increases with load current, refer to plot of i qf vs i load . note 5: this ic includes overtemperature protection that is intended to protect the device during momentary overload conditions. junction temperature will exceed 125 c when overtemperature protection is active. continuous operation above the specified maximum operating junction temperature may impair device reliability. note 6: current into a pin is positive and current out of a pin is negative. all voltages are referenced to gnd. r fwd and r on vs i load at v in = 3.6v
4 ltc4411 4411fa uu u pi fu ctio s in (pin 1): ideal diode anode and positive power supply for ltc4411. when operating ltc4411 as a switch it must be bypassed with a low esr ceramic capacitor of 1 f. x5r and x7r dielectrics are preferred for their superior voltage and temperature characteristics. gnd (pin 2): power and signal ground for the ic. ctl (pin 3): controlled shutdown pin. weak (3 a) pull- down. pull this pin high to shut down the ic. tie to gnd to enable. can be left floating when not in use. stat (pin 4): status condition indicator. this pin indi- cates the conducting status of the ltc4411. if the part is forward biased (v in > v out + v fwd ) this pin will be hi-z. if the part is reverse biased (v out > v in + v rto ), then this pin will pull down 10 a through an open-drain. when terminated to a high voltage through a 470k resistor, a high voltage indicates diode conducting. may be left floating or grounded when not in use. out (pin 5): ideal diode cathode and output of the ltc4411. bypass out with a nominal 1m ? esr capacitor of at least 4.7 f. the ltc4411 is stable with esrs down to 0.2m ? . however stability improves with higher esrs. typical perfor a ce characteristics uw r fwd vs v supply r fwd vs temperature at v in = 3.6v i qrout vs v reverse at v in = 0v 01 234 56 reverse voltage (v) leakage current (a) 10 1 100n 10n 4411 g07 t a = 60 c t a = 80 c t a = 100 c t a = 120 c supply voltage (v) 2.5 r fwd ( ? ) 0.150 0.125 0.100 0.075 0.050 3.0 3.5 4.0 4.5 4411 g04 5.0 5.5 temperature ( c) C40 r fwd ( ? ) 120 4411 g05 0 C20 20 100 40 60 80 reverse voltage (v) 01 234 56 i qrout current (a) 100 10 1 100n 4411 g06 t a = C40 c t a = 0 c t a = 40 c 0.15 0.10 0.20 0.05 0 t a = 80 c t a = 120 c 4411 g08 4411 g09 t a = C40 c t a = 0 c t a = 40 c t a = 80 c t a = 120 c v ctrl 500mv/div v stat 2v/div v out 2v/div i out 500ma/div 200 s/div v ctrl 500mv/div v stat 2v/div v out 2v/div i out 50ma/div 20 s/div i leak vs v reverse , v in = 0v ctl turn-on ctl turn-off
ltc4411 5 4411fa block diagra w figure 2. detailed block diagram C + C + + C p1 v b v b overtemp uvlo out max 10 a 3 a v ref off shdb + C 3 1 5 4 2 stat out ctl in gnd 4411 f02 a v gate figure 3. ltc4411 vs schottky diode forward conduction characteristics operatio u the ltc4411 operation is described with the aid of figure 3. forward regulation for the ltc4411 has three operation modes depending on the magnitude of the load current. for small load currents, the ltc4411 will provide a constant voltage drop; this operating mode is referred to as constant v on regulation. as the current exceeds i fwd the voltage drop will increase linearly with the current with a slope of 1/r on ; this operating mode is referred to as constant r on regulation. as the current increases fur- ther, exceeding i max , the forward voltage drop will in- crease rapidly; this operating mode is referred to as constant i on regulation. the characteristics for the following parameters: r fwd , r on , v fwd , i fwd , and i max are specified with the aid of figure 3. operation begins when the power source at in rises above the uvlo voltage of 2.4v (typ) and the ctl (control) pin is low. if only the voltage at the in pin is present, the power source to ltc4411 (v dd ) will be supplied from the in pin. the amplifier (a) will deliver a voltage proportional to the difference between v in and v out to the gate (v gate ) of the internal p-channel mosfet (p1), driving this gate voltage below v in . this will turn on p1. as p1 conducts, v out will be pulled up towards v in . the ltc4411 will then control v gate to maintain a low forward voltage drop. the system is now in forward regulation and the load at out will be powered from the supply at in. as the load current varies, v gate will be controlled to maintain a low forward voltage drop. if the load current exceeds p1s ability to deliver the current, as v gate approaches gnd, the p1 will behave as a fixed resistor, with resistance r on , whereby the forward voltage will increase with increased load current. as i load increases further (i load > i max ), the ltc4411 will regulate the load current as described below. during the forward regulation mode of operation the stat pin will be an open circuit. v fwd i oc i max i fwd forward voltage (v) 0 load current (a) 3.0 2.5 2.0 1.5 1.0 0.5 0 0.25 0.5 0.75 1.0 4411 f03 t a = 40 c slope 1/r on slope 1/r fwd schottky diode ltc4411
6 ltc4411 4411fa applicatio s i for atio wu u u introduction the ltc4411 is intended for power control applications that include low loss diode oring, fully automatic switchover from a primary to an auxiliary source of power, microcontroller controlled switchover from a primary to an auxiliary source of power, load sharing between two or more batteries, charging of multiple batteries from a single charger and high side power switching. figure 4. state transition diagram constant r on regulation constant i on regulation constant v on regulation reverse biased v in C v out < v fwd i out > i fwd i out < i fwd i out > i max i out < i max v in C v out > v fwd i stat = 0 diode on i stat = 10 a diode off i stat = 0 diode off i stat = 0 diode off i stat = 10 a diode off i stat = 0 diode on i stat = 0 diode on control shutdown under voltage lock-out over temperature shutdown t j < 140 c t j > 150 c v dd > 2.4 v dd < 2.3 v ctl < v il 4411 f04 normal operation v ctl > v ih where: v dd = max {v in , v out } v il = v th C v hyst /2 v ih = v th + v hyst /2 when the load current exceeds i max , an over current condition is detected and the ltc4411 will limit the output current. this will cause the output voltage to drop as the load current exceeds the amount of current that the ltc4411 can supply. this condition will increase the power consumption within the ltc4411. when an alternate power source is connected to the output, the ltc4411 will sense the increased voltage at out, and the amplifier (a) will increase the voltage at v gate . when v out is higher than v in + v rto , the internal power source for the ltc4411 (v dd ) will be diverted to source current from the out pin. at the same time v gate will be pulled to v dd , which will turn off p1. the system is now in the reverse turn-off mode. power to the load is being delivered from an alternate supply, and only a small operatio u current is drawn from in to sense the potential v in . during reverse turn-off mode the stat pin will sink 10 a to indicate that the diode is not conducting. when the ctl input is asserted (high), p1 will have its gate voltage pulled high, and the stat pin will sink 10 a. a 3 a pull-down current on the ctl pin will ensure a low level at this input if it is left open circuited. the overtemperature condition is detected when the internal die temperature increases beyond 150 c. the overtemperature condition will cause the gate amplifier (a) as well as p1 to be shut off. when the internal die temperature cools to below 140 c, the amplifier will turn on and revert to normal operation. note that prolonged operation under overtemperature conditions will degrade reliability. automatic powerpath control figure 1 illustrates an application circuit for automatic switchover of a load between a battery and a wall adapter or other power input. with initial application of the battery, the load will be charged up as the ltc4411 turns on. the ltc4411 will control the gate voltage of its internal mosfet to reduce the mosfets voltage drop to a low forward voltage (v fwd ). the system is now in the forward regula-
ltc4411 7 4411fa tion mode, the forward voltage will be kept low by control- ling the gate voltage of the internal mosfet to react to changes in load current. should the wall adapter input be applied, the schottky diode will pull up the output voltage, connected to the load, above the battery voltage. the ltc4411 will sense that the output voltage is higher than the battery voltage and will turn off the internal mosfet. the stat pin will then sink current indicating an auxiliary input is connected. the battery is now supplying no load current and all load current flows through the schottky diode. microcontrolled powerpath monitoring and control figure 6 illustrates an application circuit for microcontroller monitoring and control of two power sources. the microcontrollers analog inputs, perhaps with the aid of a resistor voltage divider, monitors each supply input and commands the ltc4411 through the ctl input. back-to- back mosfets are used so that the parasitic drain-source diode will not power the load when the mosfet is turned off (dual mosfets in one package are commercially available). figure 5. automatic switchover of load between a primary and an auxiliary power source with external dual p-channel mosfets figure 6. dual battery load sharing with automatic switchover of load from batteries to wall adapter load status in gnd ctl out stat ltc4411 1 2 3 5 4 c2 4.7 f c1 10 f auxiliary p-channel mosfets microcontroller primary power source auxiliary power source r1 470k 4411 f05 c1: c0805c106k8pac c2: c1206c475k8pac when both status lines are high, then both batteries are supplying load current. when both status lines are low, then wall adapter is present and supplying full load current in gnd ctl out stat ltc4411 1 2 3 bat2 4411 f06 in gnd ctl out stat ltc4411 1 2 3 wall adapter input to load c out 4.7 f status is high when bat2 is supplying load current status is high when bat1 is supplying load current bat1 470k v cc 470k v cc 5 4 c in 1 f c in 1 f c in : c0805c105k8pac c out : c1206c475k8pac turn off and no load current will be drawn from the batteries. the stat pins provide information as to which input is supplying the load current. this concept can be expanded to more power inputs. multiple battery charging figure 7 illustrates an application circuit for automatic dual battery charging from a single charger. whichever battery has the lower voltage will receive the charging current until both battery voltages are equal, then both will be charged. when both are charging simultaneously, the higher ca- pacity battery will get proportionally higher current from the charger. for li-ion batteries, both batteries will achieve the float voltage minus the forward regulation voltage of 40mv. this concept can apply to more than two batteries. the stat pin provides information as to which batteries are being charged. for intelligent control, the ctl pin input can be used with a microcontroller as shown in figure 5. figure 7. automatic dual battery charging from a single charging source in gnd ctl out stat ltc4411 1 2 3 4411 f07 in gnd ctl out stat ltc4411 1 2 3 battery charger input to load or powerpath controller to load or powerpath controller status is high when bat2 is charging status is high when bat1 is charging 470k v cc 470k v cc 5 4 bat1 bat2 applicatio s i for atio wu u u load sharing figure 6 illustrates an application circuit for dual battery load sharing with automatic switchover of load from batteries to wall adapter. whichever battery is capable of supplying the higher voltage will provide the load current until it is discharged to the voltage of the other battery. the load will then be shared between the two batteries accord- ing to the capacity of each battery. the higher capacity battery will provide proportionally higher current to the load. when a wall adapter input is applied, both ltc4411s 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 ltc4411 4411fa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2003 lt/lt 0305 rev a ? printed in usa related parts part number description comments ltc1558/ltc1559 backup battery controller with programmable output adjustable backup voltage from 1.2v nicd button cell, includes boost converter ltc1998 2.5 a, 1% accurate programmable battery detector adjustable trip voltage/hysteresis, thinsot ltc4054 800ma standalone linear li-ion battery charger no external mosfet, sense resistor or blocking diode required, with thermal regulation in thinsot charge current monitor for gas gauging, c/10 charge termination ltc4350 hot swappable load share controller allows n + 1 redundant supply, equally loads multiple power supplies connected in parallel ltc4412/ltc4412hv powerpath controller in thinsot more efficient than diode oring, automatic switching between dc sources, simplified load sharing, 3v v in 36v (ltc4412hv) package descriptio u s5 package 5-lead plastic tsot-23 (reference ltc dwg # 05-08-1635) 1.50 C 1.75 (note 4) 2.80 bsc 0.30 C 0.45 typ 5 plcs (note 3) datum a 0.09 C 0.20 (note 3) s5 tsot-23 0302 pin one 2.90 bsc (note 4) 0.95 bsc 1.90 bsc 0.80 C 0.90 1.00 max 0.01 C 0.10 0.20 bsc 0.30 C 0.50 ref note: 1. dimensions are in millimeters 2. drawing not to scale 3. dimensions are inclusive of plating 4. dimensions are exclusive of mold flash and metal burr 5. mold flash shall not exceed 0.254mm 6. jedec package reference is mo-193 3.85 max 0.62 max 0.95 ref recommended solder pad layout per ipc calculator 1.4 min 2.62 ref 1.22 ref applicatio s i for atio wu uu figure 8. logic controlled high side power switch in gnd ctl out stat ltc4411 1 2 3 5 4 to load c out 4.7 f 4411 f08 supply input logic input c in 1 f c in : c0805c105k8pac c out : c1206c475k8pac high side power switch figure 8 illustrates an application circuit for a logic con- trolled high side power switch. when the ctl pin is a logical low, the ltc4411 will turn on, supplying current to the load. when the ctl pin is a logical high, the ltc4411 will turn off and deny power to the load. if the load is powered from another (higher voltage) source, the supply connected to v in remains disconnected from the load.
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