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lt3650-8.2/lt3650-8.4 1 36508284fc typical application the lt ? 3650 is a complete monolithic 2-cell li-ion/polymer battery charger that operates over a 9v to 32v input volt- age range (11.5v minimum start-up voltage). the lt3650 provides a constant-current/constant-voltage charge characteristic, with maximum charge current externally programmable up to 2a, set using an external current sense resistor. a precondition feature trickle-charges a low voltage battery, and bad-battery detection provides a signal and suspends charging if a battery does not respond to preconditioning. the lt3650 can be con? gured to terminate charging when charge current falls to c/10, or one-tenth the programmed maximum current. once charging is terminated, the lt3650 enters a low current (85a) standby mode. an auto-restart feature starts a new charging cycle if the battery voltage drops 2.5% from the ? oat voltage, or if a new battery is inserted into a charging system. the lt3650 contains a user-programmable internal safety timer (typically set to a three hour full cycle time). the ic can be con? gured to use this internal timer if a time-based termination scheme is desired in which charging can con- tinue below c/10 until a desired time is reached. the lt3650 is available in a low pro? le (0.75mm) 3mm 3mm 12-pin dfn and 12-pin msop packages. features applications description high voltage 2 amp monolithic 2-cell li-ion battery charger 11.5v to 32v 2-cell 2a charger n wide input voltage range: 9v to 32v (40v absolute maximum) n programmable charge current: up to 2a n user-selectable termination: c/10 or onboard termination timer n dynamic charge rate programming/soft-start pin n programmable input current limit n 1mhz fixed frequency n average current mode control n 0.5% float voltage accuracy n 5% charge current accuracy n 2.5% c/10 detection accuracy n ntc resistor temperature monitor n auto-recharge at 97.5% float voltage n auto-precondition at <70% float voltage n bad-battery detection with auto-reset n binary coded open-collector status pins n 3mm 3mm dfn-12 or msop-12 package n industrial handheld instruments n 12v to 24v automotive and heavy equipment n desktop cradle chargers n notebook computers 365082 ta01a sw v in v in 11.5v to 32v clp rng/ss boost sense bat ntc timer cmpsh1-4 cmsh3-40ma cmsh3-40ma 1f 10f 10h 0.05 10f 0.68f lt3650-8.2 battery shdn chrg fault + charge current, ef? ciency and power loss vs time time (minutes) 0 charge current (a), power loss (w) efficiency (%) 1.0 2.0 3.0 0.5 1.5 2.5 35 55 75 95 45 65 85 40 80 120 160 365082 ta01b 200 20 0 60 100 140 180 v in = 20v power loss efficiency charge current l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners.
lt3650-8.2/lt3650-8.4 2 36508284fc absolute maximum ratings v in ............................................................................40v shdn , chrg , fault ............................... v in + 0.5v, 40v clp ......................................................... v in 0.5v, 40v sw ............................................................................40v sw-v in .....................................................................4.5v boost .....................................................sw + 10v, 50v sense, bat ..............................................................10v (note 1) order information lead free finish tape and reel part marking* package description temperature range lt3650edd-8.2#pbf lt3650edd-8.2#trpbf ldxt 12-lead (3mm 3mm) plastic dfn C40c to 85c lt3650idd-8.2#pbf lt3650idd-8.2#trpbf ldxt 12-lead (3mm 3mm) plastic dfn C40c to 85c lt3650edd-8.4#pbf lt3650edd-8.4#trpbf lfgr 12-lead (3mm 3mm) plastic dfn C40c to 85c lt3650idd-8.4#pbf lt3650idd-8.4#trpbf lfgr 12-lead (3mm 3mm) plastic dfn C40c to 85c lt3650emse-8.2#pbf lt3650emse-8.2#trpbf 365082 12-lead plastic msop C40c to 85c lt3650imse-8.2#pbf lt3650imse-8.2#trpbf 365082 12-lead plastic msop C40c to 85c lt3650emse-8.4#pbf lt3650emse-8.4#trpbf 365084 12-lead plastic msop C40c to 85c lt3650imse-8.4#pbf lt3650imse-8.4#trpbf 365084 12-lead plastic msop C40c to 85c consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the temperature grade is identi? ed by a label on the shipping container. consult ltc marketing for information on non-standard lead based ? nish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/ top view dd package 12-lead (3mm s 3mm) plastic dfn 12 11 8 9 10 4 5 13 3 2 1 sw boost sense bat ntc rng/ss v in clp shdn chrg fault timer 6 7 t jmax = 125c, ja = 43c/w, jc = 3c/w exposed pad (pin 13) is gnd, must be soldered to pcb 1 2 3 4 5 6 v in clp shdn chrg fault timer 12 11 10 9 8 7 sw boost sense bat ntc rng/ss top view 13 mse package 12-lead plastic msop t jmax = 125c, ja = 43c/w, jc = 3c/w exposed pad (pin 13) is gnd, must be soldered to pcb pin configuration sense-bat ............................................... C0.5v to 0.5v timer, rng/ss, ntc ..............................................2.5v operating junction temperature range (note 2) ..................................................C40c to 125c storage temperature range ...................C65c to 150c lead temperature (soldering, 10 sec) mse .................................................................. 300c
lt3650-8.2/lt3650-8.4 3 36508284fc symbol parameter conditions min typ max units lt3650 v in v in operating range v in start voltage (note 3) l l 932 11.5 v v v in(ovlo) ovlo threshold ovlo hysteresis v in rising l 32 35 1 40 v v v in(uvlo) uvlo threshold uvlo hysteresis v in rising 8.7 0.2 v v v bat(flt) battery float voltage lt3650-8.2 l 8.16 8.12 8.2 8.24 8.28 v v lt3650-8.4 l 8.36 8.32 8.4 8.44 8.48 v v v rechrg recharge battery threshold threshold voltage relative to v bat(flt) C200 mv v bat(pre) battery precondition threshold voltage ltc3650-8.2 ltc3650-8.4 5.65 5.80 v v v bat(prehyst) battery precondition threshold hysteresis 90 mv i vin operating input supply current cc/cv mode, switch-on, i sw = 0 standby mode shutdown ( shdn = 0) l 2.5 85 15 3.5 ma a a i boost boost supply current switch-on, i sw = 0 2.5v < v (boost C sw) < 8.5v 20 ma i boost /i sw boost switch drive i sw = 2a 30 ma/a v sw(on) switch-on voltage drop v in C v sw , i sw = 2a 350 mv i sw(max) switch current limit l 2.5 a v sense(pre) precondition current sense voltage v sense C v bat v bat = 5 15 mv v clp(dc) clp threshold voltage v clp C v in ; v sense C v bat = 50mv l 37.5 50 62.5 mv i clp clp input bias current 200 na v sense(dc) maximum current sense voltage v sense C v bat ; v bat = 7.5v, v rng/ss = 1.2v l 95 100 105 mv v sense(c/10) c/10 trigger sense voltage l 7.5 10 12.5 mv i bat bat input bias current charging terminated l 0.1 1 a i sense sense input bias current charging terminated l 0.1 1 a v ntc(h) ntc range limit (high) v ntc rising l 1.25 1.36 1.45 v v ntc(l) ntc range limit (low) v ntc falling l 0.27 0.29 0.315 v v ntc(hyst) ntc threshold hysteresis % of threshold 20 % r ntc(dis) ntc disable impedance minimum external impedance to gnd l 250 500 k i ntc ntc bias current v ntc = 0.8v l 47.5 50 52.5 a i rng/ss i rng/ss bias current l 45 50 55 a v rng/ss /v sense current limit programming: v rng/ss /v sense(max) v rng/ss = 0.5 l 8.5 10 11.5 v/v v shdn shutdown threshold rising l 1.17 1.20 1.23 v v shdn (hyst) shutdown hysteresis 120 mv i shdn shdn input bias current C10 na electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at v in = 20v, boost-sw = 4v, shdn = 2v, sense = bat = v bat(flt) , c timer = 0.68f.
lt3650-8.2/lt3650-8.4 4 36508284fc temperature (c) C50 65 i vin current (a) 70 75 80 100 90 0 50 75 365082 g02 95 85 C25 25 100 v rng/ss 0 0 i chg(max) (%) 20 40 60 100 0.4 0.8 1.0 365082 g03 80 0.2 0.6 1.2 typical performance characteristics battery float voltage vs temperature v in standby mode current vs temperature maximum charge current vs rng/ss voltage; i chg(max) (as a percentage of programmed i max ) t a = 25c, unless otherwise noted. temperature (c) C50 v bat(flt) (%) 0 50 75 365082 g01 0.10 0.05 0 C0.05 C 0.10 C25 25 100 125 note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the lt3650e is guaranteed to meet performance speci? cations from 0c to 85c. speci? cations over the C40c to 85c operating temperature range are assured by design, characterization and correlation with statistical process controls. the lt3650i speci? cations are guaranteed over the full C40c to 85c temperature range. high junction temperatures degrade operating lifetimes. note 3: v in voltages below the start threshold are only supported if (v boost C v sw ) > 2v. symbol parameter conditions min typ max units v chrg , v fault status low voltage 10ma load l 0.4 v i timer charge/discharge current 25 a v timer(dis) timer disable threshold l 0.1 0.25 v t timer full charge cycle timeout 3 hr precondition timeout 22.5 min timer accuracy l C10 10 % f o operating frequency l 0.9 1 1.1 mhz dc duty cycle range continuous operation l 15 90 % electrical characteristics the l denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at v in = 20v, boost-sw = 4v, shdn = 2v, sense = bat = v bat(flt) , c timer = 0.68f.
lt3650-8.2/lt3650-8.4 5 36508284fc v bat (v) 0 C0.4 i bat (ma) 0.0 0.4 0.8 2.2 1.6 1 2 2.5 2.0 1.2 C0.2 0.2 0.6 1.0 1.8 1.4 0.5 1.5 3 3.5 8 8.5 365082 g11 lt3650-8.2 switch current (a) 0 i sw /i boost 18 24 30 36 1.6 12 6 0 21 27 33 15 9 3 0.4 0.8 1.2 0.2 1.8 0.6 1.0 1.4 2.0 365082 g04 temperature (c) C50 320 switch forward drop (mv) 340 360 380 480 420 0 50 75 365082 g05 440 460 400 C25 25 100 125 i sw = 2a switch drive (i sw /i boost ) vs switch current switch forward drop (v in C v sw ) vs temperature temperature (c) C50 99.0 v sense Cv bat (mv) 99.2 99.6 99.8 100.0 101.0 100.4 0 50 75 365082 g09 99.4 100.6 100.8 100.2 C25 25 100 125 v bat = 7.5v temperature (c) C50 8 v sense Cv bat (mv) 9 10 11 12 0 50 75 365082 g07 C25 25 100 125 temperature (c) 0 v sense C v bat (mv) 40 80 20 60 100 120 45 65 85 105 125 35 135 25 55 75 95 115 365082 g10 typical performance characteristics i max current limit (v sense C v bat ) vs temperature c/10 threshold vs temperature (v sense C v bat ) cc/cv charging; sense pin bias current vs v sense thermal foldback C i max current limit (v sense C v bat ) vs temperature temperature (c) C50 49.0 v clp Cv in (mv) 49.2 49.6 49.8 50.0 51.0 50.4 0 50 75 365082 g08 49.4 50.6 50.8 50.2 C25 25 100 125 clp input limit threshold (v clp C v in ) vs temperature i chg at 50% cc/cv charging; bat pin bias current vs v bat v sense (v) 0 C350 i sense (a) C250 C150 C50 100 1 2 2.5 50 C300 C200 C100 0 0.5 1.5 5.5 6 8 8.5 365082 g06 lt3650-8.2 t a = 25c, unless otherwise noted.
lt3650-8.2/lt3650-8.4 6 36508284fc pin functions v in (pin 1): charger input supply. v in pin operating range is 9v to 32v. v in 11.5v or (v boost C v sw ) > 2v isrequired for start-up. i vin = 85a after charge ter-mination. clp (pin 2): system current limit input. system current levels can be monitored by connecting the input power supply to the clp pin and connecting a sense resistor from the clp pin to the v in pin. additional system load is drawn from the v in pin connection, and maximum system load is achieved when v clp C v vin = 50mv. the lt3650 servos the maximum charge current required to maintain programmed maximum system current. if this function is not desired, connect the clp pin to the v in pin (see the applications information section). shdn (pin 3): precision threshold shutdown pin. the enable threshold is 1.225v (rising), with 120mv of input hysteresis. when in shutdown mode, all charging functions are disabled. the precision threshold allows use of the shdn pin to incorporate uvlo functions. if the shdn pin is pulled below 0.4v, the ic enters a low current shutdown mode where the v in pin current is reduced to 15a. typi- cal shdn pin input bias current is 10na. if the shutdown function is not desired, connect the pin to the v in pin. chrg (pin 4): open-collector charger status output; typically pulled up through a resistor to a reference volt- age. this status pin can be pulled up to voltages as high as v in when disabled, and can sink currents up to 10ma when enabled. during a battery charging cycle, chrg is pulled low. when the charge cycle is terminated, the chrg pin becomes high impedance. if the internal timer is used for termination, the pin stays low during the charging cycle until the charge current drops below a c/10 rate, or i chg(max) /10. a temperature fault also causes this pin to be pulled low (see the applications information section). fault (pin 5): open-collector fault status output; typi- cally pulled up through a resistor to a reference voltage. this status pin can be pulled up to voltages as high as v in when disabled, and can sink currents up to 10ma when enabled. this pin indicates charge cycle fault conditions during a battery charging cycle. a temperature fault causes this pin to be pulled low. if the internal timer is used for termination, a bad-battery fault also causes this pin to be pulled low. if no fault conditions exist, the fault pin remains high impedance (see the applications informa- tion section). timer (pin 6): end-of-cycle timer programming pin. if a timer-based charge termination is desired, connect a capacitor from this pin to ground. full charge end-of- cycle time (in hours) is programmed with this capacitor following the equation: t eoc = c timer ? 4.4 ? 10 6 a bad-battery fault is generated if the battery does not reach the precondition threshold voltage within one-eighth of t eoc , or: t pre = c timer ? 5.5 ? 10 5 a 0.68f capacitor is typically used, which generates a timer eoc at three hours, and a precondition limit time of 22.5 minutes. if a timer-based termination is not desired, the timer function is disabled by connecting the timer pin to ground. with the timer function disabled, charging terminates when the charge current drops below a c/10 rate, or i chg(max) /10. rng/ss (pin 7): charge current programming pin. this pin allows a dynamic adjustment of the maximum charge current, and can be used to employ a soft-start function. maximum charge current is adjusted by setting the volt- age on this pin, such that the maximum desired voltage across the inductor current sense resistor (v sense C v bat ) is 0.1 ? v rng/ss , so the maximum charge current reduces to: v rng/ss ? i chg(max) this pin has an effective range from 0v to 1v. 50a is sourced from this pin, so the maximum charge current can be programmed by connecting a resistor (r rng/ss ) from rng/ss to ground, such that the voltage dropped across the resistor is equivalent to the desired program- ming voltage, or: v rng/ss = 50a ? r rng/ss soft-start functionality can be implemented by connect- ing a capacitor (c rng/ss ) from rng/ss to ground, such that the time required to charge the capacitor to 1v (full
lt3650-8.2/lt3650-8.4 7 36508284fc charge current) is the desired soft-start interval (t ss ). for no r rng/ss , this capacitor value follows the relation: cat rng ss ss / ? = 50 the rng/ss pin is pulled low during fault conditions, allowing graceful recovery from faults should soft-start functionality be implemented. both the soft-start capaci- tor and the programming resistor can be implemented in parallel. all c/10 monitoring functions are disabled while v rng/ss is below 0.1v to accommodate long soft-start intervals. rng/ss voltage can also be manipulated using an active device, employing a pulldown transistor to disable charge current or to dynamically servo maximum charge current. manipulation of the rng/ss pin with active devices that have low impedance pull-up capability is not allowed (see the applications information section). ntc (pin 8): battery temperature monitor pin. this pin is the input to the ntc (negative temperature coef? cient) thermistor temperature monitoring circuit. this function is enabled by connecting a 10k , b = 3380 ntc thermistor from the ntc pin to ground. the pin sources 50a, and monitors the voltage across the 10k thermistor. when the voltage on this pin is above 1.36v (t < 0c) or below 0.29v (t > 40c), charging is disabled and the chrg and fault pins are both pulled low. if internal timer termination is being used, the timer is paused, suspending the charg- ing cycle. charging resumes when the voltage on ntc returns to within the 0.29v to 1.36v active region. there is approximately 5c of temperature hysteresis associated with each of the temperature thresholds. the temperature monitoring function remains enabled while thermistor resistance to ground is less than 250k , so if this function is not desired, leave the ntc pin unconnected. bat (pin 9): battery voltage monitor pin. connect 10f decoupling capacitance (c bat ) from this pin to ground. depending on application requirements, larger value decoupling capacitors may be required (see the applica- tion information section). the charge function operates to achieve the ? nal ? oat voltage at this pin. the auto-restart feature initiates a new charging cycle when the voltage at the bat pin falls 2.5% below this ? oat voltage. once the charge cycle is terminated, the input bias current of the bat pin is reduced to <0.1a, to minimize battery discharge while the charger remains connected. sense (pin 10): charge current sense pin. connect the more positive voltage end of the inductor sense resistor (r sense ) to the sense pin and the other end to the bat pin. the voltage across this resistor sets the average charge current. the maximum average charge current (i max ) corresponds to 100mv across the sense resistor. this resistor can be set to program maximum charge currents as high as 2a. the sense resistor value follows the relation: r v i sense max = 01 . once the charge cycle is terminated, the input bias current of the sense pin is reduced to <0.1a, to minimize battery discharge while the charger remains connected. boost (pin 11): bootstrapped supply rail for switch drive. this pin facilitates saturation of the switch transistor. connect a 1f or greater capacitor from the boost pin to the sw pin. operating range of this pin is 0v to 8.5v, referenced to the sw pin. the voltage on the decoupling capacitor is refreshed through a rectifying diode, with the anode connected to either the battery output voltage or an external source, and the cathode connected to the boost pin. sw (pin 12): switch output pin. this pin is the output of the charger switch, and corresponds to the emitter of the switch transistor. when enabled, the switch shorts the sw pin to the v in supply. the drive circuitry for this switch is bootstrapped above the v in supply using the boost supply pin, allowing saturation of the switch for maximum ef? ciency. the effective on-resistance of the boosted switch is 0.175 . sgnd (pin 13): ground reference and backside exposed lead frame thermal connection. solder the exposed lead frame to the pcb ground plane. pin functions
lt3650-8.2/lt3650-8.4 8 36508284fc block diagram 365082 bd + C + C + C + C C + + C + C + C + C timer 10m 35v 0.1v offset 5.65v ? 1.2v v bat(flt) : 8.2v for lt3650-8.2, 8.4v for lt3650-8.4 v bat(flt) C v rechrg : 8v for lt3650-8.2, 8.2v for lt3650-8.4 v bat(pre) : 5.65v for lt3650-8.2, 5.8v for lt3650-8.4 8.7v reset enable count reset c/10 precondition 1.36v 0.29v 46 a clp boost v in sw sense bat rng/ss ntc v int 2.7v 1.3v * ** ? ss reset 1v 0.15v 1.2v 8.2v* 8v** terminate 50 a 0.7v control logic ripple counter status timer osc. ntc 0.2v 125c count count osc 1mhz latch r s r s c-ea 50 a 30mv x2.25 10 s r s 0.3v v c t die i th mode (timer or c/10) terminate r q s ss reset 50mv uvlo ovlo C + fault chrg standby shdn v-ea + C + C + C + C standby standby + C + C + C
lt3650-8.2/lt3650-8.4 9 36508284fc operation overview lt3650 is a complete monolithic, mid-power, li-ion battery charger, addressing high input voltage applications with solutions that use a minimum of external components. the ic uses a 1mhz constant-frequency, average current mode step-down architecture. the lt3650 incorporates a 2a switch that is driven by a bootstrapped supply to maximize ef? ciency during charging cycles. a wide input range allows the operation to full- charge from 9v to 32v. a precision threshold shutdown pin allows incorporation of uvlo functionality using a simple resistor divider. the ic can also be put into a low current shutdown mode, in which the input supply bias is reduced to only 15a. the lt3650 incorporates several degrees of charge current control freedom. the overall maximum charge current is set using an external inductor current sense resistor. a maximum charge current programming pin allows dynamic manipulation of the battery charge current. the lt3650 also incorporates a system input supply current limit control feature that servos the battery charge current to accommodate overall system load requirements. the lt3650 automatically enters a battery precondition mode if the sensed battery voltage is very low. in this mode, the charge current is reduced to 15% of the programmed maximum, as set by the inductor sense resistor, r sense . once the battery voltage climbs above the internally set precondition threshold, the ic automatically increases the maximum charge current to the full programmed value. the lt3650 can use a charge current based c/10 ter- mination scheme, which ends a charge cycle when the battery charge current falls to one-tenth the programmed maximum charge current. the lt3650 also contains an internal charge cycle control timer, for timer-based termina- tion. when using the internal timer, the ic combines c/10 detection with a programmable time constraint, during which the charging cycle can continue beyond the c/10 level to top-off a battery. the charge cycle terminates when a speci? c time elapses, typically three hours. when the timer-based scheme is used, the ic also supports bad- battery detection, which triggers a system fault if a battery stays in precondition mode for more than one-eighth of the total programmed charge cycle time. once charging is terminated and the lt3650 is not actively charging, the ic automatically enters a low current standby mode in which supply bias currents are reduced to 85a. if the battery voltage drops 2.5% from the full charge ? oat voltage, the lt3650 engages an automatic charge cycle restart. the ic also automatically restarts a new charge cycle after a bad-battery fault once the failed battery is removed and replaced with another battery. the lt3650 contains provisions for a battery temperature monitoring circuit. this feature monitors battery tempera- ture by using a thermistor during the charging cycle, sus- pends charging, and signals a fault condition if the battery temperature moves outside a safe charging range. the lt3650 contains two digital open-collector outputs, which provide charger status and signal fault conditions. these binary coded pins signal battery charging, standby or shutdown modes, battery temperature faults and bad- battery faults. general operation (see block diagram) the lt3650 uses average current mode control architec- ture, such that the ic servos directly to average charge current. the lt3650 senses charger output voltage via the bat pin. the difference between the voltage on this pin and an internal ? oat voltage reference is integrated by the voltage error ampli? er (v-ea). this ampli? er generates an error voltage on its output (i th ), which corresponds to the average current sensed across the inductor current sense resistor, r sense , which is connected between the sense and bat pins. the i th voltage is then divided down by a factor of 10, and imposed on the input of the current er- ror ampli? er (c-ea). the difference between this imposed voltage and the current sense resistor voltage is integrated, with the resulting voltage (v c ) used as a threshold that is compared against an internally generated ramp. the output of this comparison controls the chargers switch.
lt3650-8.2/lt3650-8.4 10 36508284fc operation the i th error voltage corresponds linearly to average current sensed across the inductor current sense resistor, allowing maximum charge current control by limiting the effective voltage range of i th . a clamp limits this voltage to 1v which, in turn, limits the current sense voltage to 100mv. this sets the maximum charge current, or the current delivered while the charger is operating in con- stant-current (cc) mode, which corresponds to 100mv across r sense . this maximum charge current level can also be manipulated through the rng/ss pin (see the rng/ss: dynamic charge current adjust and rng/ss: soft-start sections). if the voltage on the bat pin is below v bat(pre) , the lt3650 engages precondition mode. during the precondition inter- val, the charger continues to operate in constant-current mode, but the maximum charge current is reduced to 15% of the maximum programmed value as set by r sense . when the charger output voltage on the bat pin approaches the ? oat voltage (v bat(flt) ), the charger transitions into constant-voltage (cv) mode, and charge current is reduced from the maximum value. as this occurs, the i th voltage falls from the limit clamp and servos to lower voltages. the ic monitors the i th voltage as it is reduced, and detection of the c/10 charge current is achieved when i th = 0.1v. if the charger is con? gured for c/10 termina- tion, this threshold is used to terminate the charge cycle. once the charge cycle is terminated, the chrg status pin becomes high impedance and the charger enters low current standby mode. the lt3650 contains an internal charge cycle timer that terminates a successful charge cycle after a programmed amount of time. this timer is typically programmed to achieve end-of-cycle (eoc) in three hours, but can be con? gured for any amount of time by setting an appropriate timing capacitor value (c timer ). when timer termination is used, the charge cycle does not terminate after c/10 is achieved. because the chrg status pin responds to the c/10 current level, the ic will indicate a fully charged battery status, but the charger will continue to source low currents into the battery until the programmed eoc time has elapsed, at which time the charge cycle will terminate. at eoc, when the charging cycle terminates, if the battery did not achieve at least 97.5% of the full ? oat voltage, charging is deemed unsuccessful. the lt3650 will then re-initiate, and charging will continue for another full timer cycle. use of the timer function also enables bad-battery detec- tion. this fault condition is achieved if the battery does not respond to preconditioning and the charger remains in (or enters) precondition mode after one-eighth of the programmed charge cycle time. a bad-battery fault halts the charging cycle, the chrg status pin goes high imped- ance, and the fault pin is pulled low. when the lt3650 terminates a charging cycle, whether through c/10 detection or by reaching timer eoc, the average current mode analog loop remains active but the internal ? oat voltage reference is reduced by 2.5%. because the voltage on a successfully charged battery is at the full ? oat voltage, the voltage error amp detects an overvoltage condition and rails low. when the voltage error amp output drops below 0.3v, the ic enters standby mode, where most of the internal circuitry is disabled, and the v in bias current is reduced to 85a. when the voltage on the bat pin drops below the reduced ? oat reference level, the output of the voltage error amp will climb, at which point the ic comes out of standby mode and a new charging cycle is initiated.
lt3650-8.2/lt3650-8.4 11 36508284fc v in input supply the lt3650 is biased directly from the charger input supply through the v in pin. this supply provides large switched currents, so a high quality, low esr decoupling capacitor is recommended to minimize voltage glitches on v in . the v in decoupling capacitor (c vin ) absorbs all input switching ripple current in the charger, so it must have an adequate ripple current rating. rms ripple current (i cvin(rms) ) is: ii v v v v cvin rms chg max bat in in bat () () ~ ?? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 1 2 which has a maximum at v in = 2 ? v bat , where: i cvin(rms) = i chg(max) /2 the simple worst-case of 1/2 ? i chg(max) is commonly used for design. bulk capacitance is a function of desired input ripple volt- age ( v in ), and follows the relation: ci vv v f in bulk max bat in in () ? / () = ? ? ? ? ? ? 10f is typically adequate for most charger applications. boost supply the boost bootstrapped supply rail drives the internal switch and facilitates saturation of switch transistor. oper- ating range of the boost pin is 0v to 8.5v, as referenced to the sw pin. connect a 1f or greater capacitor from the boost pin to the sw pin. the voltage on the decoupling capacitor is refreshed through a diode, with the anode connected to/from either the battery output voltage or an external source, and the cathode connected to the boost pin. rate the diode av- erage current greater than 0.1a, and its reverse voltages greater than v in(max) . v in / boost start-up requirement the lt3650 operates with a v in range of 9v to 32v, however, a start-up voltage requirement exists due to the nature of the nonsynchronous step-down switcher topology used for the charger. if there is no boost supply available, the internal switch requires (v in C v sw ) > 3v to operate. this requirement does not exist if the boost supply is available and (v boost C v sw ) > 2v. when an lt3650 charger is not switching, the sw pin is at the same potential as the battery, which can be as high as v bat(flt) . for reliable start-up, the v in supply must be at least 3v above the sw pin. the minimum start-up speci- ? cation of v in at or above 11.5v provides ample margin to satisfy this requirement. once switching begins, the boost supply capacitor gets charged such that (v boost C v sw ) > 2v, and the v in requirement no longer applies. in low v in applications, the boost supply can be powered by an external source for start-up, eliminating the v in start-up requirement. v bat output decoupling an lt3650 charger output requires bypass capacitance connected from the bat pin to ground (c bat ). a 10f ce- ramic capacitor is required for all applications. in systems where the battery can be disconnected from the charger output, additional bypass capacitance may be desired for visual indication of a no-battery condition (see the status pins section). if it is desired to operate a system load from the lt3650 charger output when the battery is disconnected, additional bypass capacitance is required. in this type of application with the charger being used as a dc/dc converter, exces- sive ripple and/or low amplitude oscillations can occur without additional output bulk capacitance. for these ap- plications, place a 100f low esr nonceramic capacitor (chip tantalum or organic semiconductor capacitors such as sanyo os-cons or poscaps) from bat to ground, in parallel with the 10f ceramic bypass capacitor. this additional bypass capacitance may also be required in systems where the battery is connected to the charger through long wires. the voltage rating on c bat must meet or exceed the battery ? oat voltage. applications information
lt3650-8.2/lt3650-8.4 12 36508284fc r sense : charge current programming the lt3650 charger is con? gurable to charge at average currents as high as 2a. maximum charge current is set by choosing an inductor sense resistor such that the desired maximum average current through that sense resistor creates a 100mv drop, or: r i sense max avg = 01 . () where i max(avg) is the maximum average charge current. a 2a charger, for example, would use a 0.05 sense resistor. to 35% of i max , so an inductor value can be determined by setting 0.25 < i max < 0.35. magnetics vendors typically specify inductors with maximum rms and saturation current ratings. select an inductor that has a saturation current rating at or above (1+ i max /2) ? i max , and an rms rating above i max . in- ductors must also meet a maximum volt-second product requirement. if this speci? cation is not in the data sheet of an inductor, consult the vendor to make sure the maximum volt-second product is not being exceeded by your design. the minimum required volt-second product is: v v v vs bat bat in max ?? () 1 ? ? ? ? ? ? ? () applications information figure 1. programming maximum charge current using r sense 365082 f01 sw boost sense bat r sense lt3650 figure 2. 2a charger switched inductor value (r sense = 0.05 ) 25% to 35% i max ripple current figure 3. 1.3a charger switched inductor value (r sense = 0.075 ) 25% to 35% i max ripple current inductor selection the primary criteria for inductor value selection in an lt3650 charger is the ripple current created in that inductor. once the inductance value is determined, an inductor must also have a saturation current equal to or exceeding the maximum peak current in the inductor. an inductor value (l), given the desired amount of ripple current ( i max ) can be approximated using the relation: l i rvv vv v max sense bat f bat f = ? ? ? ? ? ? + () ? + 10 1 ?? ? i in max f v h () + ? ? ? ? ? ? ? ? ? ? ? ? ? ? () in the previous relation, i max is the normalized ripple current, v in(max) as the maximum operational voltage, and v f is the forward voltage of the rectifying schottky diode. ripple current is typically set within a range of 25% maximum operational v in voltage (v) 9 0 switched inductor value (h) 2 6 8 10 14 15 21 24 4 12 12 18 27 32 30 365082 f02 915 21 24 12 18 27 32 30 maximum operational v in voltage (v) 0 switched inductor value (h) 2 6 8 10 20 14 4 16 18 12 365082 f03
lt3650-8.2/lt3650-8.4 13 36508284fc recti? er selection the recti? er diode in an lt3650 battery charger provides a current path for the inductor current when the main power switch is disabled. the recti? er is selected based upon forward voltage, reverse voltage, and maximum current. a schottky diode is required, as low forward voltage yields the lowest power loss and highest ef? ciency. the recti? er diode must be rated to withstand reverse voltages greater than the maximum v in voltage. the minimum average diode current rating (i diode(max) ) is calculated with maximum output current (i max ), maximum operational v in , and output at the precondition threshold (v bat(pre) ): i iv v v diode max max in max bat pre in ma () () () ( ? > ? () x x a ) () for example, a recti? er diode for an 8.2v, 1.5a charger with a 20v maximum input voltage would require: ior i diode max diode max () () .?( . ) , > ? > 15 20 565 20 1..1a clp: system current limit the lt3650 contains a powerpath tm control feature to support multiple load systems. the charger adjusts output current in response to a system load if overall input supply current exceeds the programmed maximum value. maximum input supply current is set by choosing a sense resistor (r clp ) such that the desired maximum current through that sense resistor creates a 50mv drop, or: r i clp max in = 005 . () where i max(in) is the maximum input current. a 1.5a system limit, for example, would use a 33m sense resistor. the lt3650 integrates the clp signal internally, so average current limiting is performed in most cases without the need for external ? lter elements. applications information figure 4. r clp sets the input supply current limit 365082 f0 4 clp system load input supply v in r clp lt3650 365082 f05 0.5a 1.0a 1.5a lt3650 input current (i vin ) system load current figure 5. clp limit: charger current vs system load current with 1.5a limit powerpath is a trademark of linear technology corporation.
lt3650-8.2/lt3650-8.4 14 36508284fc rng/ss: dynamic charge current adjust the lt3650 gives the user the capability to adjust maximum charge current dynamically through the rng/ss pin. the voltage on the rng/ss pin corresponds to ten times the maximum voltage across the sense resistor (r sense ). the default maximum sense voltage is 100mv, so maximum charge current can be expressed as: i max(rng/ss) = i max ? v rng/ss where i max(rng/ss) is the maximum charge current if v rng/ss is within 0v to 1v. voltages higher than 1v have no effect on the maximum charge current. the lt3650 sources 50a from the rng/ss pin, such that a current control voltage can be set by simply connecting an appropriately valued resistor to ground, following the relation: r v a rng ss rng ss / / = 50 for example, to reduce the maximum charge current to 50% of the original value, which corresponds to a maximum sense voltage of 50mv, rng/ss would be set to 0.5v. r v a k rng ss / . == 05 50 10 this feature could be used, for example, to switch in a reduced charge current level. active servos can also be used to impose voltages on the rng/ss pin, provided they can only sink current. active circuits that source current cannot be used to drive the rng/ss pin. resistive pull-ups can be used, but extreme care must be taken not to exceed the 2.5v absolute maximum voltage on the pin. rng/ss: soft-start soft-start functionality is also supported by the rng/ss pin. 50a is sourced from the rng/ss pin, so connecting a capacitor from the rng/ss pin to ground (c rng/ss ) cre- ates a linear voltage ramp. the maximum charge current follows this voltage. thus, the charge current increases from zero to the fully programmed value as the capacitor charges from 0v to 1v. the value of c rng/ss is calculated based on the desired time to full current (t ss ) following the relation: c rng/ss = 50a ? t ss the rng/ss pin is pulled to ground internally when charg- ing is terminated so each new charging cycle begins with a soft-start cycle. rng/ss is also pulled to ground during bad-battery and ntc fault conditions, so a graceful recovery from these faults is possible. applications information figure 6. using the rng/ss pin for digital control of maximum charge current figure 7. driving the rng/ss pin with a current-sink active servo ampli? er figure 8. using the rng/ss pin for soft-start 365082 f06 rng/ss 10k logic high = half current lt3650 365082 f08 rng/ss c prog lt3650 365082 f07 rng/ss servo reference lt3650 + C
lt3650-8.2/lt3650-8.4 15 36508284fc status pins the lt3650 reports charger status through two open-col- lector outputs, the chrg and fault pins. these pins can accept voltages as high as v in , and can sink up to 10ma when enabled. the chrg pin indicates that the charger is delivering current at greater than a c/10 rate, or one-tenth of the programmed maximum charge current. the fault pin signals bad-battery and ntc faults. these pins are binary coded, and signal following the table below, where on indicates the pin pulled low, and off indicates pin high impedance: voltage is achieved, the charge current falls until the c/10 threshold is reached, at which time the charger terminates and the lt3650 enters standby mode. the chrg status pin follows the charger cycle and is high impedance when the charger is not actively charging. when v bat drops below 97.5% of the full-charged ? oat voltage, whether by battery loading or replacement of the battery, the charger automatically re-engages and starts charging. there is no provision for bad-battery detection if c/10 termination is used. timer termination the lt3650 supports a timer-based termination scheme, in which a battery charge cycle is terminated after a speci? c amount of time elapses. timer termination is engaged when a capacitor (c timer ) is connected from the timer pin to ground. the timer cycle eoc (t eoc ) occurs based on c timer following the relation: c timer = t eoc ? 2.27 ? 10 C7 (hours) timer eoc is typically set to three hours, which requires a 0.68f capacitor. the chrg status pin continues to signal charging at a c/10 rate, regardless of which termination scheme is used. when timer termination is used, the chrg status pin is pulled low during a charging cycle until the charger output current falls below the c/10 threshold. the charger continues to top off the battery until timer eoc, when the lt3650 terminates the charging cycle and enters standby mode. termination at the end of the timer cycle only occurs if the charging cycle was successful. a successful charge cycle occurs when the battery is charged to within 2.5% of the full-charge ? oat voltage. if a charge cycle is not successful at eoc, the timer cycle resets and charging continues for another full timer cycle. when v bat drops below 97.5% of the full-charge ? oat voltage, whether by battery loading or replacement of the battery, the charger automatically re-engages and starts charging. applications information table 1. status pins state table status pins state charger status chrg fault off off not charging standby or shutdown mode off on bad-battery fault (precondition timeout/eoc failure) on off normal charging at c/10 or greater on on ntc fault (pause) if the battery is removed from an lt3650 charger that is con? gured for c/10 termination, a sawtooth waveform of approximately 100mv appears at the charger output, due to cycling between termination and recharge events. this cycling results in pulsing at the chrg output. an led connected to this pin will exhibit a blinking pattern, indicating to the user that a battery is not present. the frequency of this blinking pattern is dependent on the output capacitance. c/10 termination the lt3650 supports a low current based termination scheme, where a battery charge cycle terminates when the current output from the charger falls to below one- tenth the maximum current, as programmed with r sense . the c/10 threshold current corresponds to 10mv across r sense . this termination mode is engaged by shorting the timer pin to ground. when c/10 termination is used, an lt3650 charger sources battery charge current as long as the average current level remains above the c/10 threshold. as the full-charge ? oat
lt3650-8.2/lt3650-8.4 16 36508284fc preconditioning and bad-battery fault an lt3650 charger has a precondition mode, in which charge current is limited to 15% of the programmed i max , as set by r sense . the precondition current corresponds to 15mv across r sense . precondition mode is engaged while the voltage on the bat pin is below the precondition threshold (v bat(pre) ). once the bat voltage rises above the precondition threshold, normal full-current charging can commence. the lt3650 incorporates 1.5% of threshold hysteresis to prevent mode glitching. when the internal timer is used for termination, bad-bat- tery detection is engaged. this fault detection feature is designed to identify failed cells. a bad-battery fault is triggered when the voltage on bat remains below the precondition threshold for greater than one-eighth of a full timer cycle (one-eighth eoc). a bad-battery fault is also triggered if a normally charging battery re-enters precondition mode after one-eighth eoc. when a bad-battery fault is triggered, the charging cycle is suspended, so the chrg status pin becomes high impedance. the fault pin is pulled low to signal a fault detection. the rng/ss pin is also pulled low during this fault, to accommodate a graceful restart, in the event that a soft-start function is incorporated (see the rng/ss: soft-start section). cycling the chargers power or shdn function initiates a new charging cycle, but an lt3650 charger does not require a reset. once a bad-battery fault is detected, a new timer charging cycle initiates when the bat pin exceeds the precondition threshold voltage. during a bad-battery fault, 0.5ma is sourced from the charger; removing the failed battery allows the charger output voltage to rise and initiate a charge cycle reset. as such, removing a bad battery resets the lt3650, so a new charge cycle is started by connecting another battery to the charger output. battery temperature fault: ntc the lt3650 can accommodate battery temperature moni- toring by using an ntc (negative temperature coef? cient) thermistor close to the battery pack. the temperature monitoring function is enabled by connecting a 10k , b = 3380 ntc thermistor from the ntc pin to ground. if the ntc function is not desired, leave the pin unconnected. the ntc pin sources 50a, and monitors the voltage dropped across the 10k thermistor. when the voltage on this pin is above 1.36v (0c) or below 0.29v (40c), the battery temperature is out of range, and the lt3650 triggers an ntc fault. the ntc fault condition remains until the voltage on the ntc pin corresponds to a temperature within the 0c to 40c range. both hot and cold thresholds incorporate hysteresis that corresponds to 5c. if higher operational charging temperatures are desired, the temperature range can be expanded by adding se- ries resistance to the 10k ntc resistor. adding a 0.91k resistor will increase the effective temperature threshold to 45c. during an ntc fault, charging is halted and both status pins are pulled low. if timer termination is enabled, the timer count is suspended and held until the fault condition is relieved. the rng/ss pin is also pulled low during this fault, to accommodate a graceful restart in the event that a soft-start function is being incorporated (see the rng/ss: soft-start section). thermal foldback the lt3650 contains a thermal foldback protection feature that reduces maximum charger output current if the ic junction temperature approaches 125c. in most cases, on-chip temperatures servo such that any overtemperature conditions are relieved with only slight reductions in maximum charger current. in some cases, the thermal foldback protection feature can reduce charger currents below the c/10 threshold. in applications that use c/10 termination (timer = 0v), the lt3650 will suspend charging and enter standby mode until the overtemperature condition is relieved. applications information
lt3650-8.2/lt3650-8.4 17 36508284fc layout considerations the lt3650 switch node has rise and fall times that are typically less than 10ns to maximize conversion ef? ciency. the switched node (pin sw) trace should be kept as short as possible to minimize high frequency noise. the input capacitor (c in ) should be placed close to the ic to minimize this switching noise. short, wide traces on these nodes also help to avoid voltage stress from inductive ringing. the boost decoupling capacitor should also be in close proximity to the ic to minimize inductive ringing. the sense and bat traces should be routed together and kept as short as possible. shielding these signals from switching noise with ground is recommended. high current paths and transients should be kept iso- lated from battery ground, to assure an accurate output voltage reference. effective grounding can be achieved by considering switched current in the ground plane, and careful component placement and orientation can effectively steer these high currents such that the battery reference does not get corrupted. figure 9 illustrates an effective grounding scheme using component placement to control ground currents. when the switch is enabled (loop #1), current ? ows from the input bypass capacitor (c in ) through the switch and inductor to the battery posi- tive terminal. when the switch is disabled (loop #2), the current to the battery positive terminal is provided from ground through the freewheeling schottky diode (d f ). in both cases, these switched currents return to ground via the output bypass capacitor (c bat ). the lt3650 packaging has been designed to ef? ciently remove heat from the ic via the exposed pad on the backside of the package, which is soldered to a copper footprint on the pcb. this footprint should be made as large as possible to reduce the thermal resistance of the ic case to ambient air. applications information figure 9. component orientation isolates high current paths from sensitive nodes 365082 f09 sw v in sense bat lt3650 c in c bat d f v bat r sense 2 1 +
lt3650-8.2/lt3650-8.4 18 36508284fc 365082 ta02 outa v C Cina +ina v + +inb outb Cinb lt6004 + b = 3800 10k sw v in clp rng/ss boost sense bat ntc timer cmpsh1-4 cmhz4684ltm si1032r (2) (3) (1) 0.05 b340a v in 12v to 32v 1f 10f l1 10h lt3650 d4 b340a 182k 274k 470k shdn chrg fault 5.1k d5 10f 10nf 3.3nf d2 5.1k cmhz4684ltm 4.99k 274k typical applications 12v to 32v 2a charger with c/10 termination. a dual lt6004 provides thermal foldback, reducing maximum charge current for temperatures higher than 35c 12v to 32v 2a charger with three hour eoc termination and removable battery pack. the rng/ss pin is used to reduce the maximum charge current if 12v < v in < 20v; input uvlo = 10v. ntc range is extended to +45c. the charger can supply loads up to the maximum charge current with no battery connected. 365082 ta03a sw v in v in 12v to 32v clp rng/ss boost sense bat ntc timer cmpsh1-4 system load mm5z9v1st1 (9.1v) 1f 10h 0.05 lt3650 10f 36k 3k 0.68f 0.91k shdn chrg fault 0.1f cmsh3-40ma cmsh3-40ma 10f 100f b = 3380 10k + + 365082 ta03b 0.5 0 10 14 12 16 v in 18 22 20 32 2.0 1.5 1.0 maximum charge current (a) rng/ss pin foldback: i chg(max) vs v in temperature (c) 25 0 maximum charge current (a) 0.5 1.0 1.5 2.0 2.5 30 35 40 45 50 365082 ta02b
lt3650-8.2/lt3650-8.4 19 36508284fc 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description dd package 12-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1725 rev a) 3.00 p 0.10 (4 sides) note: 1. drawing is not a jedec package outline 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 and tie bars shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.40 p 0.10 bottom viewexposed pad 1.65 p 0.10 0.75 p 0.05 r = 0.115 typ 1 6 12 7 pin 1 top mark (see note 6) 0.200 ref 0.00 C 0.05 (dd12) dfn 0106 rev a 0.23 p 0.05 pin 1 notch r = 0.20 or 0.25 s 45 o chamfer 2.38 p 0.10 2.25 ref 0.45 bsc recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 0.25 p 0.05 2.25 ref 2.38 p 0.05 1.65 p 0.05 2.10 p 0.05 0.70 p 0.05 3.50 p 0.05 package outline 0.45 bsc mse package 12-lead plastic msop , exposed die pad (reference ltc dwg # 05-08-1666 rev b) msop (mse12) 0608 rev b 0.53 p 0.152 (.021 p .006) seating plane 0.18 (.007) 1.10 (.043) max 0.22 C?0.38 (.009 C .015) typ 0.86 (.034) ref 0.650 (.0256) bsc 12 11 10 9 8 7 note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 0.254 (.010) 0 o C 6 o typ detail a detail a gauge plane recommended solder pad layout 2.845 p 0.102 (.112 p .004) 4.039 p 0.102 (.159 p .004) (note 3) 1.651 p 0.102 (.065 p .004) 0.1016 p 0.0508 (.004 p .002) 123456 3.00 p 0.102 (.118 p .004) (note 4) 0.406 p 0.076 (.016 p .003) ref 4.90 p 0.152 (.193 p .006) 12 7 detail b 1 6 bottom view of exposed pad option 2.845 p 0.102 (.112 p .004) detail b corner tail is part of the leadframe feature. for reference only no measurement purpose 0.12 ref 0.35 ref 5.23 (.206) min 3.20 C 3.45 (.126 C .136) 0.889 p 0.127 (.035 p .005) 0.42 p 0.038 (.0165 p .0015) typ 0.65 (.0256) bsc
lt3650-8.2/lt3650-8.4 20 36508284fc linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2009 lt 0809 rev c ? printed in usa related parts typical application part number description comments lt1511 3a constant-current/constant-voltage battery charger high ef? ciency, minimum external components to fast charge lithium, nimh and nicd batteries, 24-lead so package lt1513 sepic constant or programmable current/ constant-voltage battery charger charger input voltage may be higher, equal to or lower than battery voltage, 500khz switching frequency, dd-pak and to-220 packages lt1571 1.5a switching charger 1- or 2-cell li-ion, 500khz or 200khz switching frequency, termination flag, 16- and 28-lead ssop packages ltc1729 li-ion battery charger termination controller trickle charge preconditioning, temperature charge quali? cation, time or charge current termination, automatic charger and battery detection, and status output, ms8 and so-8 packages lt1769 2a switching charger constant-current/constant-voltage switching regulator, input current limiting maximizes charge current, 20-lead tssop and 28-lead ssop packages lt3650-4.1/ lt3650-4.2 high voltage 2-amp monolithic 1-cell li-ion battery charger v in : 4.75 to 32v (40v absolute maximum), f sw : 1mhz, user-selectable c/10 or programmable termination timer, 3mm 3mm dfn-12 package ltc4002 standalone li-ion switch mode battery charger complete charger for 1- or 2-cell li-ion batteries, onboard timer termination, up to 4a charge current, 10-lead dfn and so-8 packages ltc4006 small, high ef? ciency, fixed voltage li-ion battery charger with termination complete charger for 2-, 3- or 4-cell li-ion batteries, ac adapter current limit and thermistor sensor, 16-lead narrow ssop package ltc4007 high ef? ciency, programmable voltage battery charger with termination complete charger for 3- or 4-cell li-ion batteries, ac adapter current limit, thermistor sensor and indicator outputs, 24-lead ssop package ltc4008 4a, high ef? ciency, multi-chemistry battery charger complete charger for 2- to 6-cell li-ion batteries or 4- to 18-cell nickel batteries, up to 96% ef? ciency, 20-lead ssop package ltc4009/ ltc4009-1/ ltc4009-2 4a, high ef? ciency, multi-chemistry battery charger constant-current/constant-voltage switching regulator charger, resistor voltage/ current programming, ac adapter current limit and thermistor sensor and indicator outputs 1- to 4-cell li, up to 18-cell ni, sla and supercap compatible; 4mm 4mm qfn-20 package, ltc4009-1 version for 4.1v float voltage li-ion, ltc4009-2 version for 4.2v float voltage li-ion cells. 12v to 32v 1.5a powerpath charger with c/10 termination and 1a input supply limit. status pins use led indicators 365082 ta04 sw v in clp rng/ss boost sense bat ntc timer bas40 b240a b240a system load 1f 0.068 7 lt3650 15h 0.1f input supply 12v to 32v 1a 47k shdn chrg fault 10k 402k 0.05 10k b = 3380 10k + 10f b240a 10f

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