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ltc4061 1 4061fa features descriptio u applicatio s u typical applicatio u + v cc timer prog i det bat chrg acpr ntc ltc4061 gnd 800ma 619 ? 1f v in 4.3v to 8v 4061 ta01a 4.2v single cell li-ion battery c/5 en time (hours) 0 0.5 1.5 2.5 3.0 charge current (ma) battery voltage (v) 2.0 900 800 700 600 500 400 300 200 100 0 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5 3.4 4061 ta01b 1.0 battery current battery voltage v cc = 5v t a = 25c charge current programmable up to 1a charges single cell li-ion batteries directly from usb port preset charge voltage with 0.35% accuracy thermistor input for temperature quali? ed charging input supply present logic output thermal regulation maximizes charge rate without risk of overheating* programmable charge current detection/ termination programmable charge termination timer smart pulsing error feature smartstart tm prolongs battery life 20a charger quiescent current in shutdown available in a low pro? le (0.75mm) 10-lead (3mm 3mm) dfn package standalone linear li-ion battery charger with thermistor input the ltc ? 4061 is a full-featured, ? exible, standalone linear charger for single-cell lithium-ion batteries. it is capable of operating within usb power speci? cations. both programmable time and programmable current based termination schemes are available. furthermore, the ? c ? h ? r ? g open-drain status pin can be programmed to indicate the battery charge state according to the needs of the application. additional safety features designed to maximize battery lifetime and reliability include ntc bat- tery temperature sensing and the smartstart tm charging algorithm. no external sense resistor or external blocking diode is required for charging due to the internal mosfet archi- tecture. internal thermal feedback regulates the charge current to maintain a constant die temperature during high power operation or high ambient temperature condi- tions. the charge current is programmed with an external resistor. with power applied, the ltc4061 can be put into shutdown mode to reduce the supply current to 20a and the battery drain current to less than 2a. other features include smart recharge, usb ? c ? / ? 5 cur- rent programming input, undervoltage lockout and ac present logic. 800ma single cell li-ion battery charger (c/10 termination) handheld computers portable mp3 players digital cameras complete charge cycle (1100mah battery) smartstart is a trademark of linear technology corporation. *protected by u.s. patents including 6522118. , ltc and lt are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners.
ltc4061 2 4061fa absolute axi u rati gs w ww u for atio package/order i uu w electrical characteristics input supply voltage (v cc ) ........................ C0.3v to 10v ? e ? n, ? a ? c ? p ? r, ? c ? h ? r ? g, ntc, prog, ? c ? / ? 5, bat ..................................................... C0.3v to 10v timer, i det .................................... C0.3v to v cc + 0.3v bat short-circuit duration ............................ continuous v cc pin current ...........................................................1a bat pin current ..........................................................1a maximum junction temperature (note 5) ............ 125c operating temperature range (note 2) ...C40c to 85c storage temperature range ...................C65c to 125c order part number dd part marking t jmax = 125c, ja = 40c/w (note 3) exposed pad is ground (pin 11) must be soldered to pcb consult ltc marketing for parts speci? ed with wider operating temperature ranges. lbjs ltc4061edd (note 1) the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cc = 5v, unless otherwise noted. symbol parameter conditions min typ max units v cc input supply voltage 4.3 8 v i cc input supply current charge mode (note 4), r prog = 10k 240 500 a standby mode, charge terminated 130 300 a shutdown ( ? ? e ? n = 5v, v cc < v bat or v cc < v uv ) 20 50 a v float v bat regulated output voltage 4.185 4.2 4.215 v 0 t a 85c 4.175 4.2 4.225 v i bat bat pin current r prog = 10k, constant current mode 93 100 107 ma r prog = 1.25k, constant current mode 760 800 840 ma standby mode, charge terminated 1 2 a shutdown mode 1 2 a v prog prog pin voltage r prog = 10k, constant current mode 0.97 1 1.03 v r prog = 1.25k, constant current mode 0.97 1 1.03 v v ? a ? c ? p ? r ? a ? c ? p ? r output low voltage i ? a ? c ? p ? r = 5ma 0.1 0.25 v v ? c ? h ? r ? g ? c ? h ? r ? g output low voltage i ? c ? h ? r ? g = 5ma 0.1 0.25 v i trikl trickle charge current v bat < v trikl , r prog = 10k 6 10 14 ma v bat < v trikl , r prog = 1.25k 60 80 100 ma v trikl trickle charge threshold voltage v bat rising 2.8 2.9 3 v hysteresis 100 mv v uv v cc undervoltage lockout voltage from low to high 3.7 3.8 3.9 v hysteresis 200 mv v asd v cc C v bat lockout threshold voltage v cc from low to high, v bat = 4.3v 145 190 230 mv v cc from high to low, v bat = 4.3v 10 45 75 mv r ? e ? n ? e ? n pin pull-down resistor 2 3.4 5 m v ? e ? n ? e ? n input threshold voltage ? e ? n rising, 4.3v < v cc < 8v 0.4 0.7 1 v hysteresis 70 mv v ct charge termination mode threshold v timer from high to low 0.4 0.7 1 v voltage hysteresis 50 mv top view 10 9 6 7 8 11 4 5 3 2 1 v cc prog i det en c/5 bat ntc timer acpr chrg
ltc4061 3 4061fa electrical characteristics the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are at t a = 25c. v cc = 5v, unless otherwise noted. symbol parameter conditions min typ max units v ut user termination mode threshold v timer from low to high 3.9 4.2 v voltage hysteresis 50 mv i detect charge current detection threshold r det = 1k, 0 t a 85c 90 100 110 ma r det = 2k, 0 t a 85c 45 50 55 ma r det = 10k, 0 t a 85c 8 10 12 ma r det = 20k, 0 t a 85c 3.8 5 6.2 ma v rechrg recharge threshold voltage v float C v rechrg, 0 t a 85c 65 100 135 mv t ss soft-start time i bat from 0 to i chrg 100 s t term termination comparator filter time current termination mode 0.8 1.5 2.5 ms t rechrg recharge comparator filter time 3 7 14 ms t timer charge cycle time c timer = 0.1f 2.55 3 3.45 hr r ? c ? / ? 5 ? c ? /5 pin pull-down resistor 2 3.4 5 m v ? c ? / ? 5 ? c ? /5 input threshold voltage ? c ? / ? 5 rising, 4.3v < v cc < 8v 0.4 0.7 1 v hysteresis 70 mv v ntc-hot ntc pin hot threshold voltage v ntc falling 0.35 ? v cc v v ntc rising 0.36 ? v cc v v ntc-cold ntc pin cold threshold voltage v ntc rising 0.76 ? v cc v v ntc falling 0.75 ? v cc v v ntc-dis ntc pin disable threshold voltage v ntc falling 70 85 100 mv hysteresis 50 mv f ? c ? h ? r ? g ntc fault pulsing frequency current/user termination mode 1.5 hz time termination mode c timer = 0.1f 1 1.5 2 hz t lim junction temperature in constant 105 c temperature mode r on power fet on resistance v bat = 3.85v, i cc = 175ma, r prog = 2k 375 m (between v cc and bat) note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired. note 2: the ltc4061 is 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: failure to correctly solder the exposed pad of the package to the pc board will result in a thermal resistance much higher than 40c/w. note 4: supply current includes prog pin current and i det pin current (approximately 100a each) but does not include any current delivered to the battery through the bat pin (approximately 100ma). note 5: this ic includes overtemperature protection that is intended to protect the device during momentary overload conditions. overtemperature protection will become active at a junction temperature greater than the maximum operating temperature. continuous operation above the speci? ed maximum operating junction temperature may impair device reliability.
ltc4061 4 4061fa charge current (ma) 0 v bat (v) 600 1000 4061 g01 200 400 800 4.26 4.24 4.22 4.20 4.18 4.16 4.14 4.12 4.10 temperature (c) C50 v float (v) 4.215 4.210 4.205 4.200 4.195 4.190 4.185 C25 02550 4061 g02 75 100 C50 C25 0 25 50 75 100 C50 C25 0 25 50 75 100 temperature (c) v prog (v) 4061 g05 1.006 1.004 1.002 1.000 0.998 0.996 0.994 v prog (v) 0 i bat (ma) 1200 1000 800 600 400 200 0 0.2 0.4 0.6 0.8 4061 g04 1.0 1.2 temperature (c) i trickle (ma) 84 82 80 78 76 4061 g07 C50 C25 0 25 50 75 100 temperature (c) v trickle (v) 2.96 2.94 2.92 2.90 2.88 2.86 2.84 4061 g08 v bat (v) 3.0 i bat (ma) 550 450 350 250 150 50 3.8 4061 g09 3.2 3.4 3.6 4.0 v cc = 5v r prog = 1k v cc = 5v r prog = 10k r prog = 10k c/5 = v cc v cc = 5v v bat = 2.5v r prog = 1.25k v cc = 5v r prog = 1.25k v cc = 5v r prog = 1k c/5 = 5v v timer = 5v v cc = 5v r prog = 2k v cc = 4.3v v cc = 8v c/5 = 5v c/5 = 0v 4061 g03 v cc (v) 4.0 v float (v) 8.0 5.0 6.0 7.0 4.5 5.5 6.5 7.5 4.26 4.24 4.22 4.20 4.18 4.16 4.14 4.12 4.10 r prog = 1k t a = 25c i bat = 10ma 4061 g06 v cc (v) 4.0 v prog (v) 8.0 5.0 6.0 7.0 1.006 1.004 1.002 1.000 0.998 0.996 0.994 4.5 5.5 6.5 7.5 v cc = 5v v bat = 4v r prog = 10k c/5 = 5v typical perfor uw ce characteristics a battery regulated output (float) voltage vs charge current battery regulated output (float) voltage vs temperature prog pin voltage vs temperature (constant-current mode) charge current vs prog pin voltage trickle charge current vs temperature trickle charge threshold voltage vs temperature charge current vs battery voltage battery regulated output (float) voltage vs supply voltage prog pin voltage vs v cc (constant-current mode)
ltc4061 5 4061fa temperature (c) C50 C25 0 i bat (ma) 400 1000 0 50 75 4061 g13 4061 g14 200 800 600 25 100 125 r prog = 1.25k onset of thermal regulation r prog = 2k v cc (v) 4.0 i bat (ma) 8.0 5.0 6.0 7.0 104 102 100 98 96 4.5 5.5 6.5 7.5 temperature (c) C50 v recharge (v) 4.16 4.14 4.12 4.10 4.08 4.06 4.04 C25 02550 4061 g15 75 100 temperature (c) C50 500 450 400 350 300 250 C25 02550 4061 g16 75 100 v cc = 4v i bat = 200ma temperature (c) C50 1.7 1.6 1.5 1.4 1.3 1.2 C25 02550 4061 g12 75 100 c timer = 0.1f v cc = 8v v cc = 4.3v v cc = 8v v cc = 4.3v v cc = 5v v bat = 4v c/5 = 5v r prog = 10k 4061 g11 v cc (v) 4.0 f chrg (hz) 8.0 5.0 6.0 7.0 1.60 1.55 1.50 1.45 1.40 1.35 1.30 4.5 5.5 6.5 7.5 f chrg (hz) c timer = 0.1f C50 C25 0 25 50 75 100 temperature (c) t timer (minutes) 195 190 185 180 175 170 165 4061 g10 c timer = 0.1f v cc = 4.3v v cc = 8v 4 06 1 g 17 4061 g18 temperature (c) C50 25 75 C25 0 50 100 v uv (v) 3.900 3.875 3.850 3.825 3.800 3.775 3.750 3.725 3.700 v bat (v) 0 i bat (ma) 3.0 900 800 700 600 500 400 300 200 100 0 0.5 4.5 1.0 1.5 2.0 2.5 3.5 4.0 ntc fault pulsing frequency vs v cc ntc fault pulsing frequency vs temperature charge current vs ambient temperature with thermal regulation charge current vs supply voltage recharge threshold voltage vs temperature power fet on resistance vs temperature typical perfor uw ce characteristics a internal charge timer vs temperature undervoltage lockout voltage vs temperature charge current vs battery voltage
ltc4061 6 4061fa 4061 g22 4061 g19 4061 g20 4061 g25 4061 g26 temperature ( c) temperature ( c) ?0 25 75 ?5 0 50 100 temperature ( c) ?0 25 75 ?5 0 50 100 ?0 25 75 ?5 0 50 100 4.0 3.5 3.0 2.5 2.0 1.5 v c/5 (mv) 900 850 800 750 700 650 600 4.0 3.5 3.0 2.5 2.0 1.5 temperature ( c) ?0 v chrg (v) 0.6 0.5 0.4 0.3 0.2 0.1 0 25 75 ?5 0 50 100 temperature ( c) ?0 v acpr (v) 0.6 0.5 0.4 0.3 0.2 0.1 0 25 75 ?5 0 50 100 v cc = 5v v cc = 5v i acpr = 5ma v cc = 5v i chrg = 5ma temperature ( c) ?0 v en (mv) 900 850 800 750 700 650 600 ?5 02550 4061 g21 75 100 temperature ( c) ?0 i cc ( a) 70 60 50 40 30 20 10 ?5 02550 4061 g23 75 100 v cc = 5v en = v cc v cc = 4.3v v cc = 8v v cc = 5v i acpr (ma) 4061 g24 v acpr (v) 04 1 2 3 160 140 120 100 80 60 40 20 0 v cc = 5v v bat = 4v t a = 40 c t a = 25 c t a = 90 c v chrg (v) 0 i chrg (ma) 160 140 120 100 80 60 40 20 0 1 23 4 4061 g27 v cc = 5v v bat = 4v t a = 25 c t a = 40 c t a = 90 c ? e ? n pin pulldown resistance vs temperature ? c ? / ? 5 pin threshold voltage (high-to-low) vs temperature ? c ? / ? 5 pin pulldown resistance vs temperature ? c ? h ? r ? g pin output low voltage vs temperature ? a ? c ? p ? r pin output low voltage vs temperature typical perfor uw ce characteristics a shutdown supply current vs temperature and v cc ? e ? n pin threshold voltage (on-to-off) vs temperature ? a ? c ? p ? r pin i-v curve ? c ? h ? r ? g pin i-v curve
ltc4061 7 4061fa bat (pin 1): charge current output. this pin provides charge current to the battery and regulates the ? nal ? oat voltage to 4.2v. ntc (pin 2): input to the ntc (negative temperature coef- ? cient) thermistor temperature monitoring circuit. under normal operation, connect a thermistor from the ntc pin to ground and a resistor of equal value from the ntc pin to v cc . when the voltage at this pin drops below 0.35 ? v cc at hot temperatures or rises above 0.76 ? v cc at cold, charging is suspended, the internal timer is frozen and the ? c ? ? h ? r ? g pin output will start to pulse at 1.5hz. pulling this pin below 0.016 ? v cc disables the ntc feature. there is approximately 2c of temperature hysteresis associated with each of the input comparators thresholds. timer (pin 3): timer program and termination select pin. this pin selects which method is used to terminate the charge cycle. connecting a capacitor, c timer , to ground selects charge time termination. the charge time is set by the following formula: time hours hours c f or cf time hours hours timer timer () . . () () = = 3 01 01 3 connecting the timer pin to ground selects charge cur- rent termination, while connecting the pin to v cc selects user termination. see applications information for more information on current and user termination. acpr (pin 4): open-drain power supply present status output. the power supply status indicator pin has two states: pull-down and high impedance. this output can be used as a logic interface or as a led driver. in the pull-down state, an nmos transistor capable of sinking 10ma pulls down on the ? ? a ? c ? p ? r pin. the state of this pin is dependent on the value of v cc and bat: it requires that v cc is 190mv greater than v bat and greater than v uvlo . see applications information. ? c ? h ? r ? g (pin 5): open-drain charge status output. the charge status indicator pin has three states: pull-down, uu u pi fu ctio s pulse at 1.5hz or 6hz and high impedance. this output can be used as a logic interface or as a led driver. in the pull-down state, an nmos transistor capable of sinking 10ma pulls down on the ? c ? h ? r ? g pin. the state of this pin depends on the value of i detect as well as the termina- tion method being used and the state of the ntc pin. see applications information. ? c ? / ? 5 (pin 6): ? c ? / ? 5 enable input. used to control the amount of current drawn from the usb port. a logic high on the ? c ? / ? 5 pin sets the current limit to 100% of the current programmed by the prog pin. a logic low on the ? c ? / ? 5 pin sets the current limit to 20% of the current programmed by the prog pin. an internal 3m pull-down resistor defaults the ? c ? / ? 5 pin to its low current state. ? e ? n (pin 7): charger enable input. a logic high on the ? e ? n pin places the charger into shutdown mode, where the input quiescent current is less than 50a. a logic low on this pin enables charging. an internal 3m pull-down resistor to ground defaults the charger to its enabled state. i det (pin 8) : current detection threshold program pin. the current detection threshold, i detect , is set by con- necting a resistor, r detect , to ground. i detect is set by the following formula: i r r i v r or r v i detect prog det chg det det detect == = 10 100 100 the ? c ? h ? r ? g pin becomes high impedance when the charge current drops below i detect . i detect can be set to 1/10th the programmed charge current by connecting i det di- rectly to prog. if the i det pin is not connected, the ? c ? h ? r ? g output remains in its pull-down state until the charge time elapses and terminates the charge cycle. see applications information. this pin is clamped to approximately 2.4v. driving this pin to voltages beyond the clamp voltage should be avoided. prog (pin 9): charge current program and charge cur- rent monitor. the charge current is set by connecting a
ltc4061 8 4061fa block diagra w + + + 11 9 8 3 ca ma 1.2v 2.9v prog i det r det c timer r prog 0.1v to bat 0.2v 1v 0.1v + + c3 c2 logic t a t die 105? shdn 4061 bd gnd + va bat 1000 1 1 v cc 1 10 i detect rechrg 4.1v to bat en 3m sel timer counter oscillator ntc logic en c/5 c/5 c/5 stop chrg acpr 3m 5 6 7 + c1 acpr 4 2 hot cold dis resistor, r prog , to ground. when charging in constant current mode, this pin servos to 1v. the voltage on this pin can be used to measure the charge current using the following formula: i v r bat prog prog = 1000 uu u pi fu ctio s v cc (pin 10): positive input supply voltage. provides power to the battery charger. this pin should be bypassed with a 1f capacitor. gnd (exposed pad) (pin 11): ground. this pin is the back of the exposed pad package and must be soldered to the pcb copper for minimal thermal resistance.
ltc4061 9 4061fa operatio u the ltc4061 is designed to charge single cell lithium-ion batteries. using the constant current/constant voltage algorithm, the charger can deliver up to 1a of charge current with a ? nal ? oat voltage accuracy of 0.35%. the ltc4061 includes an internal p-channel power mosfet and thermal regulation circuitry. no blocking diode or external sense resistor is required; thus, the basic charger circuit requires only two external components. normal operation the charge cycle begins when the voltage at the v cc pin rises above the uvlo level and a discharged battery is connected to bat. if the bat pin voltage is below 2.9v, the charger enters trickle charge mode. in this mode, the ltc4061 supplies 1/10th of the programmed charge current in order to bring the battery voltage up to a safe level for full current charging. once the bat pin voltage rises above 2.9v, the charger enters constant current mode, where the programmed charge current is supplied to the battery. when the bat pin approaches the ? nal ? oat voltage (4.2v), the ltc4061 enters constant voltage mode and the charge current decreases as the battery becomes fully charged. the ltc4061 offers several methods with which to ter- minate a charge cycle. connecting an external capacitor to the timer pin activates an internal timer that stops the charge cycle after the programmed time period has elapsed. grounding the timer pin and connecting a resis- tor to the i det pin causes the charge cycle to terminate once the charge current falls below a set threshold when the charger is in constant voltage mode. connecting the timer pin to v cc disables internal termination, allowing external charge user termination through the ? e ? n input. see applications information for more information on charge termination methods. programming charge current the charge current is programmed using a single resistor from the prog pin to ground. when the charger is in the constant current mode, the voltage on the prog pin is 1v. the battery charge current is 1000 times the current out of the prog pin. the program resistor and the charge current are calculated by the following equations: r v i i v r prog chg chg prog == 1000 1000 , the charge current out of the bat pin can be determined at any time by monitoring the prog pin voltage and ap- plying the following equation: i v r bat prog prog = 1000 smartstart when the ltc4061 is initially powered on or brought out of shutdown mode, the charger checks the battery voltage. if the bat pin is below the recharge threshold of 4.1v (which corresponds to approximately 80-90% battery capacity), the ltc4061 enters charge mode and begins a full charge cycle. if the bat pin is above 4.1v, the ltc4061 enters standby mode and does not begin charging. this feature reduces the number of unnecessary charge cycles, prolonging battery life. automatic recharge when the charger is in standby mode, the ltc4061 continuously monitors the voltage on the bat pin. when the bat pin voltage drops below 4.1v, the charge cycle is automatically restarted and the internal timer is reset to 50% of the programmed charge time (if time termination is being used). this feature eliminates the need for peri- odic charge cycle initiations and ensures that the battery is always fully charged. automatic recharge is disabled in user termination mode. thermal regulation an internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 105c. this feature protects the ltc4061 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the ltc4061. the charge current can be set according to typical (not worst-case) ambient temperatures with the assurance that the charger will automatically reduce the current in worst-case conditions.
ltc4061 10 4061fa undervoltage lockout (uvlo) an internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until v cc rises above the undervoltage lockout threshold (3.8v). the uvlo circuit has a built-in hysteresis of 200mv. furthermore, to protect against reverse current in the power mosfet, the uvlo circuit keeps the charger in shutdown mode if v cc falls to less than 45mv above the battery voltage. hysteresis of 145mv prevents the charger from cycling in and out of shutdown. manual shutdown at any point in the charge cycle, the charger can be put into shutdown mode by pulling the ? e ? n pin high. this reduces the supply current to less than 50a and the battery drain current of the charger to less than 2a. a new charge cycle can be initiated by ? oating the ? e ? n pin or pulling it low. if shutdown is not required, leaving the pin disconnected continuously enables the circuit. trickle-charge and defective battery detection when the bat pin voltage is below the 2.9v trickle charge threshold (v trikl ), the charger reduces the charge current to 10% of the programmed value. if the battery remains in trickle charge for more than 25% of the total programmed charge time, the charger stops charging and enters a fault state, indicating that the battery is defective 1 . the ltc4061 indicates the fault state by driving the ? c ? h ? r ? g open-drain output with a square wave. the duty cycle of this oscillation is 50% and the frequency is set by c timer : f f c hz chrg timer = 01 6 . a led driven by the ? c ? h ? r ? g output exhibits a pulsing pattern, indicating to the user that the battery needs replacing. to exit the fault state, the charger must be restarted either by toggling the ? e ? n input or removing and reapplying power to v cc . charge status output ( ? c ? h ? r ? g) the charge status indicator pin has three states: pull-down, pulse at 1.5hz or 6hz and high impedance. in the pull-down state, an nmos transistor pulls down on the ? c ? h ? r ? g pin operatio u capable of sinking up to 10ma. a pull-down state indicates that the ltc4061 is charging a battery and the charge cur- rent is greater than i detect (which is set by the external component r det ). a high impedance state indicates that the charge current has dropped below i detect . in the case where the i det pin is left unconnected (r det = , i detect = 0), a high impedance state on ? c ? h ? r ? g indicates that the ltc4061 is not charging. smart pulsing error feature ltc4061 has two different pulsing states at ? c ? h ? r ? g pull- down pin: 1) 6hz (50% duty cycle) due to defective battery detec- tion (see trickle-charge and defective battery detection section); 2) 1.5hz (25% duty cycle if in time termination, 50% duty cycle if in charge current or user termination) due to ntc out-of-temperature condition. ntc thermistor (ntc) the temperature of the battery is measured by placing a negative temperature coef? cient (ntc) thermistor close to the battery pack. the ntc circuitry is shown in figure 1. to use this feature, connect the ntc thermistor, r ntc , between the ntc pin and ground and a resistor, r nom , from the ntc pin to v cc . r nom should be a 1% resistor with a value equal to the value of the chosen ntc thermistor at 25c (this value is 100k for a vishay nths0603n01n1003j thermistor). the ltc4061 goes into hold mode when the resistance, r hot , of the ntc thermistor drops to 0.53 times the value of r nom or ap- proximately 53k , which corresponds to approximately 40c. hold mode freezes the timer and stops the charge cycle until the thermistor indicates a return to a valid tem- perature. as the temperature drops, the resistance of the ntc thermistor rises. the ltc4061 is designed to go into hold mode when the value of the ntc thermistor increases to 3.26 times the value of r nom . this resistance is r cold . for a vishay nths0603n01n1003j thermistor, this value is 326k , which corresponds to approximately 0c. the hot and cold comparators each have approximately 2c of hysteresis to prevent oscillation about the trip point. grounding the ntc pin disables the ntc function. for more details refer to the application information section. 1 the defective battery detection feature is only available when time termination is being used.
ltc4061 11 4061fa + + + 0.35 ?v cc 0.76 ?v cc 0.016 ?v cc too cold too hot enable r ntc r nom 2 ltc4061 v cc 4061 f01 ntc operatio u programming charge termination the ltc4061 can terminate a charge cycle using one of several methods, allowing the designer considerable ? ex- ibility in choosing an ideal charge termination algorithm. table 1 shows a brief description of the different termina- tion methods and their behaviors. figure 1. ntc circuit information charge time termination connecting a capacitor (c timer ) to the timer pin enables the timer and selects charge time termination. the total charge time is set by: time hours f c hours timer () . = 01 3 applicatio s i for atio wu uu table 1. method charge time termination mode charge current termination timer 0.1? to gnd i det r det to gnd charger description charges for 3 hours. after 3 hours, the charger stops charging and enters standby mode. recharge cycles last for 1.5 hours. charges for 3 hours. after 3 hours, the charger stops charging and enters standby mode. recharge cycles last for 1.5 hours. charges until charge current drops below i det , then enters standby mode. pull-down state when charging. high impedance state when charging is stopped. pulsing state available when ntc is used and is still charging. pull-down state when charging. high impedance state when charging is stopped. pulsing state available when ntc is used and is still charging. chrg output description pull-down state while i bat > i det . high impedance state while i bat < i detect or when charging is stopped. pulsing state available when ntc is used and is still charging. pull-down state while i bat > i detect . high impedance state while i bat < i detect or when charging is stopped. pulsing state available when ntc is used and is still charging. 0.1? to gnd gnd r det to gnd user selectable charge termination v cc r det to gnd charges indefinitely. charges indefinitely. smartstart is disabled. v cc nc charges indefinitely. smartstart is disabled. pull-down state when charging. high impedance state when charging is stopped. pulsing state available when ntc is used and is still charging. pull-down state when charging. high impedance state when charging is stopped. pulsing state available when ntc is used and is still charging. gnd nc nc
ltc4061 12 4061fa + v cc chrg prog i det c timer 0.1f v in 4061 f02 bat 500ma timer r det 1k r prog 2k ltc4061 gnd c/5 figure 2. time termination mode. the charge cycle ends after 3 hours. when the programmed time has elapsed, the charge cycle terminates and the charger enters standby mode. subsequent recharge cycles terminate when 50% of the programmed time has elapsed. the i det pin determines the behavior of the ? c ? h ? r ? g output. connecting a resistor (r det ) from the i det pin to ground sets the charge current detection threshold, i detect : i r r i v r or r v i detect prog det chg det det detect == = 10 100 100 when the charge current (i bat ) is greater than i detect , the ? c ? h ? r ? g output is in its pull-down state. when the charger enters constant voltage mode operation and the charge current falls below i detect , the ? c ? h ? r ? g output becomes high impedance, indicating that the battery is almost fully charged. the ? c ? h ? r ? g output will also become high impedance once the charge time elapses. if the i det pin is not connected, the ? c ? h ? r ? g output remains in its pull- down state until the charge time elapses and terminates the charge cycle. figure 2 shows a charger circuit using charge time termi- nation that is programmed to charge at 500ma. once the charge current drops below 100ma in constant voltage mode (as set by r det ), the ? c ? h ? r ? g output turns off the led. this indicates to the user that the battery is almost fully charged and ready to use. the ltc4061 continues to charge the battery until the internal timer reaches 3 hours (as set by c timer ). during recharge cycles, the ltc4061 charges the battery until the internal timer reaches 1.5 hours. figure 3 describes the operation of the ltc4061 charger when charge time termination is used. charge current termination connecting the timer pin to ground selects charge cur- rent termination. with this method, the timer is disabled and a resistor (r det ) must be connected from the i det pin to ground. i detect is programmed using the same equation stated in the previous section. the charge cycle terminates when the charge current falls below i detect . this condition is detected using an internal ? ltered comparator to monitor the i det pin. when the i det pin falls below 100mv for longer than t term (typically 1ms), charging is terminated. when charging, transient loads on the bat pin can cause the i det pin to fall below 100mv for short periods of time before the dc current has dropped below the i detect threshold. the 1.5ms ? lter time (t term ) on the internal comparator ensures that transient loads of this nature do not result in premature charge cycle termination. once the average charge current drops below i detect , the charger terminates the charge cycle. the ? c ? h ? r ? g output is in a pull-down state while charging and in a high impedance state once charging has stopped. figure 4 describes the operation of the ltc4061 charger when charge current termination is used. user-selectable charge termination connecting the timer pin to v cc selects user-selectable charge termination, in which all of the internal termination features are disabled. the charge cycle continues inde? - nitely until the charger is shut down through the ? e ? n pin. the i det pin programs the behavior of the ? c ? h ? r ? g output in the same manner as when using charge time termination. if the i det pin is not connected, the ? c ? h ? r ? g output remains in its pull-down state until the charger is shut down. with user-selectable charge termination, the smartstart feature is disabled; when the charger is powered on or enabled, the ltc4061 automatically begins charging, regardless of the battery voltage. figure 5 describes charger operation when user-selectable charge termina- tion is used. applicatio s i for atio wu uu
ltc4061 13 4061fa applicatio s i for atio wu uu figure 3. state diagram of a charge cycle using charge time termination charge mode full current chrg state: pull-down if i bat > i detect hi-z if i bat < i detect charge time elapses 1/4 charge time elapses bat < 4.1v 4061 f03 trickle charge mode 1/10th full current bat > 2.9v bat < 2.9v 2.9v < bat < 4.1v bat > 4.1v en = 5v or uvlo condition standby mode no charge current chrg state: hi-z shutdown mode i cc drops to 20a chrg state: hi-z chrg state: pull-down defective battery fault mode no charge current chrg state: pulsing recharge mode full current chrg state: pull-down if i bat > i detect hi-z if i bat < i detect 1/2 charge time elapses power on en = 0v or uvlo condition stops
ltc4061 14 4061fa s i for atio applicatio wu u u figure 4. state diagram of a charge cycle using charge current termination figure 5. state diagram of a charge cycle using user-selectable termination charge mode full current i bat < i detect in voltage mode 4061 f04 trickle charge mode 1/10th full current bat > 2.9v bat < 2.9v 2.9v < bat < 4.1v bat > 4.1v bat < 4.1v en = 5v or uvlo condition standby mode no charge current chrg state: hi-z shutdown mode i cc drops to 20a chrg state: hi-z chrg state: pull-down chrg state: pull-down power on en = 0v or uvlo condition stops charge mode full current 4061 f05 trickle charge mode 1/10th full current bat > 2.9v bat < 2.9v 2.9v < bat en = 5v or uvlo condition shutdown mode i cc drops to 20a chrg state: hi-z chrg state: pull-down power on en = 0v or uvlo condition stops chrg state: pull-down if i bat > i detect hi-z if i bat < i detect
ltc4061 15 4061fa applicatio s i for atio wu uu programming c/10 current detection/termination in most cases, an external resistor, r det , is needed to set the charge current detection threshold, i detect . however, when setting i detect to be 1/10th of i chg , the i det pin can be connected directly to the prog pin. this reduces the component count, as shown in figure 6. when prog and i det are connected in this way, the full- scale charge current, i chg , is programmed with a different equation: r v i i v r prog chg chg prog == 500 500 , stability considerations the battery charger constant voltage mode feedback loop is stable without any compensation provided a battery is connected. however, a 1f capacitor with a 1 series resistor to gnd is recommended at the bat pin to reduce noise when no battery is present. when the charger is in constant current mode, the prog pin is in the feedback loop, not the battery. the constant current stability is affected by the impedance at the prog pin. with no additional capacitance on the prog pin, the charger is stable with program resistor values as high as 10k ; however, additional capacitance on this node reduces the maximum allowed program resistor value. power dissipation when designing the battery charger circuit, it is not neces- sary to design for worst-case power dissipation scenarios because the ltc4061 automatically reduces the charge current during high power conditions. the conditions that cause the ltc4061 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the ic. most of the power dissipation is generated from the internal charger mosfet. thus, the power dissipation is calculated to be approximately: p d = (v cc C v bat ) ? i bat p d is the power dissipated, v cc is the input supply voltage, v bat is the battery voltage and i bat is the charge current. the approximate ambient temperature at which the thermal feedback begins to protect the ic is: t a = 105c C p d ? ja t a = 105c C (v cc C v bat ) ? i bat ? ja example: an ltc4061 operating from a 5v wall adapter is programmed to supply 800ma full-scale current to a discharged li-ion battery with a voltage of 3.3v. assuming ja is 40c/w (see thermal considerations), the ambient temperature at which the ltc4061 will begin to reduce the charge current is approximately: t a = 105c C (5v C 3.3v) ? (800ma) ? 40c/w t a = 105c C 1.36w ? 40c/w = 105c C 54.4c t a = 50.6c the ltc4061 can be used above 50.6c ambient, but the charge current will be reduced from 800ma. the ap- proximate current at a given ambient temperature can be approximated by: i ct vv bat a cc bat ja = 105 ( ) using the previous example with an ambient tem- perature of 60c, the charge current will be reduced to approximately: i cc vvcw c ca ima bat bat = = = 105 60 53340 45 68 662 (.) / / + v cc prog i det v in bat 500ma timer r det 2k r prog 2k ltc4061 gnd + v cc prog i det v in 4061 f06 bat 500ma timer r prog 1k ltc4061 gnd c/5 c/5 figure 6. two circuits that charge at 500ma full-scale current and terminate at 50ma
ltc4061 16 4061fa applicatio s i for atio wu uu it is important to remember that ltc4061 applications do not need to be designed for worst-case thermal conditions, since the ic will automatically reduce power dissipation if the junction temperature reaches approximately 105c. thermistors the ltc4061 ntc comparator trip points were designed to work with thermistors whose resistance-temperature characteristics follow vishay dales r-t curve 1. the vishay nths0603n01n1003j is an example of such a thermistor. however, vishay dale has many thermistor products that follow the r-t curve 1 characteristic in a variety of sizes. furthermore, any thermistor whose ratio of r cold to r hot is about 6 also works (vishay dale r-t curve 1 shows a ratio of r cold to r hot of 3.266/0.5325 = 6.13). power conscious designers may want to use thermistors whose room temperature value is greater than 10k . vishay dale has a number of values of thermistor from 10k to 100k that follow the r-t curve 1. using dif- ferent r-t curves, such as vishay dale r-t curve 2, is also possible. this curve, combined with ltc4061 internal thresholds, gives temperature trip points of approximately 0c (falling) and 40c (rising), a delta of 40c. this delta in temperature can be moved in either direction by changing the value of r nom with respect to r ntc . increasing r nom moves both trip points to lower temperatures. likewise a decrease in r nom with respect to r ntc moves the trip points to higher temperatures. to calculate r nom for a shift to lower temperatures, use the following equation: r r ratc nom cold ntc = 3 266 25 . where r cold is the resistance ratio of r ntc at the desired cold temperature trip point. if you want to shift the trip points to higher temperatures, use the following equations: r r ratc nom hot ntc = 0 5325 25 . where r hot is the resistance ratio of r ntc at the desired hot temperature trip point. here is an example using 10k r-t curve 2 thermistor from vishay dale. the difference between the trip points is 40c, from before, and we want the cold trip point to be 0c, which would put the hot trip point at 40c. the r nom needed is calculated as follows: r r ratc kk nom cold ntc = =?=? 3 266 25 2 816 3 266 10 8 62 . . . ? the nearest 1% value for r nom is 8.66k . this is the value used to bias the ntc thermistor to get cold and hot trip points of approximately 0c and 40c respectively. to extend the delta between the cold and hot trip points, a resistor, r1, can be added in series with r ntc . the values of the resistors are calculated as follows: r rr rrrr nom cold hot cold hot hot = = ? ? ? ? ? ? ? .. . .. ? ) 3 266 0 5325 0 5325 3 266 0 5325 1 where r nom is the value of the bias resistor, r hot and r cold are the values of r ntc at the desired temperature trip points. continuing the example from before with a desired hot trip point of 50c: r rr k k k is the nearest value nom cold hot == =? .. ? . . ) .. .,. % . 3 266 0 5325 10 2 816 0 4086 3 266 0 5325 88 887 1 the ? nal solution is r nom = 8.87k , r1 = 604 and r ntc = 10k at 25c. ntc trip point error when a 1% resistor is used for r hot , the major error in the 40c trip point is determined by the tolerance of the ntc thermistor. a typical 100k ntc thermistor has 10% tolerance. by looking up the temperature coef- ? cient of the thermistor at 40c, the tolerance error can rk is the nearest value 1 10 0 5325 3 266 0 5325 2 816 0 4086 0 4086 604 604 1 = ? ? ? ? ? ? =? . .. ? . . ) . ,%.
ltc4061 17 4061fa applicatio s i for atio wu uu be calculated in degrees centigrade. consider the vishay nths0603n01n1003j thermistor, which has a tempera- ture coef? cient of C 4%/c at 40c. dividing the tolerance by the temperature coef? cient, 5%/(4%/c) = 1.25c, gives the temperature error of the hot trip point. the cold trip point error depends on the tolerance of the ntc thermistor and the degree to which the ratio of its value at 0c and its value at 40c varies from 6.14 to 1. therefore, the cold trip point error can be calculated us- ing the tolerance, tol, the temperature coef? cient of the thermistor at 0c, tc (in %/c), the value of the thermistor at 0c, r cold , and the value of the thermistor at 40c, r hot . the formula is: temperature error c tol r r tc cold hot () . = + ? ? ? ? ? ? 1 614 1 100 for example, the vishay nths0603n01n1003j thermistor with a tolerance of 5%, tc of -5%/c and r cold / r hot of 6.13, has a cold trip point error of: temperature error c cc () . . ? ? , . = + ? ? ? ? ? ? = 1005 614 6 13 1 100 5 095 105 thermal considerations in order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the ltc4061 package is properly soldered to the pc board ground. correctly soldered to a 2500mm 2 double sided 1oz copper board, the ltc4061 has a ther- mal resistance of approximately 40c/w. failure to make thermal contact between the exposed pad on the backside of the package and the copper board will result in thermal resistances far greater than 40c/w. as an example, a correctly soldered ltc4061 can deliver over 800ma to a battery from a 5v supply at room temperature. without a good backside thermal connection, this number could drop to less than 500ma. v cc bypass capacitor many types of capacitors can be used for input bypassing; however, caution must be exercised when using multi-layer ceramic capacitors. because of the self-resonant and high q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions such as connecting the charger input to a live power source. adding a 1.5 resistor in series with an x5r ceramic capacitor will minimize start-up voltage transients. for more information, see application note 88. charge current soft-start and soft-stop the ltc4061 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. when a charge cycle is initiated, the charge current ramps from zero to the full-scale current over a period of approximately 100s. likewise, internal circuitry slowly ramps the charge cur- rent from full-scale to zero when the charger is shut off or self terminates. this has the effect of minimizing the transient current load on the power supply during start-up and charge termination. reverse polarity input voltage protection in some applications, protection from reverse polarity voltage on v cc is desired. if the supply voltage is high enough, a series blocking diode can be used. in other cases, where the diode voltage drop must be kept low, a p-channel mosfet can be used (as shown in figure 7). v cc v in 4061 f07 ltc4061 drain-bulk diode of fet figure 7. low loss input reverse polarity protection usb and wall adapter power the ltc4061 allows charging from both a wall adapter and a usb port. figure 8 shows an example of how to combine wall adapter and usb power inputs. a p-channel
ltc4061 18 4061fa applicatio s i for atio wu uu figure 8. combining wall adapter and usb power + v cc d1 prog i det 3.3k 2k mn1 5v wall adapter i chg = 800ma usb power i chg = 500ma mp1 4061 f08 bat ltc4061 1.25k li-ion battery system load 1k c/5 mosfet, mp1, is used to prevent back conducting into the usb port when a wall adapter is present and a schottky diode, d1, is used to prevent usb power loss through the 1k pull-down resistor. typically a wall adapter can supply more current than the 500ma limited usb port. therefore, an n-channel mosfet, mn1, and an extra 3.3k program resistor are used to increase the charge current to 800ma when the wall adapter is present.
ltc4061 19 4061fa package descriptio u dd package 10-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1699) 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. 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-2). check the ltc website data sheet for current status of variation assignment 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 0.10 bottom view?xposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.38 0.10 (2 sides) 1 5 10 6 pin 1 top mark (see note 6) 0.200 ref 0.00 ?0.05 (dd10) dfn 1103 0.25 0.05 2.38 0.05 (2 sides) recommended solder pad pitch and dimensions 1.65 0.05 (2 sides) 2.15 0.05 0.50 bsc 0.675 0.05 3.50 0.05 package outline 0.25 0.05 0.50 bsc
ltc4061 20 4061fa usb/wall adapter power li-ion charger (using charge current termination) full-featured li-ion charger (using time termination) typical applicatio s u related parts 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/tp 0305 1k rev a ? printed in usa thinsot and powerpath are trademarks of linear technology corporation. + v cc timer bat prog i det ltc4061 gnd 2k 1k 11 8 9 1 1f 10 3 6 2.5k 5v wall adapter usb power 4061 ta03 li-ion cell c c/5 + chrg timer prog i det 5 3 9 8 bat acpr ntc 1 2 ltc4061 gnd 100k 100k ntc 11 619 ? 1.25k 1k 1k 800ma 10 1f 0.1f v in 5v 4061 ta02 v in single cell li-ion battery v cc 6 4 c/5 part number description comments battery chargers ltc1734 lithium-ion linear battery charger in thinsot tm simple thinsot charger, no blocking diode, no sense resistor needed ltc1734l lithium-ion linear battery charger in thinsot low current version of ltc1734, 50ma i chrg 180ma ltc4002 switch mode lithium-ion battery charger standalone, 4.7v v in 24v, 500khz frequency, 3 hour charge termination ltc4050 lithium-ion linear battery charger controller features preset voltages, c/10 charger detection and programmable timer, input power good indication, thermistor interface ltc4052 monolithic lithium-ion battery pulse charger no blocking diode or external power fet required, 1.5a charge current ltc4053 usb compatible monolithic li-ion battery charger standalone charger with programmable timer, up to 1.25a charge current ltc4054 standalone linear li-ion battery charger thermal regulation prevents overheating, c/10 termination, with integrated pass transistor in thinsot c/10 indicator, up to 800ma charge current ltc4057 lithium-ion linear battery charger up to 800ma charge current, thermal regulation, thinsot package ltc4058 standalone 950ma lithium-ion charger in dfn c/10 charge termination, battery kelvin sensing, 7% charge accuracy ltc4059 900ma linear lithium-ion battery charger 2mm x 2mm dfn package, thermal regulation, charge current monitor output ltc4063 li-ion charger with linear regulator up to 1a charge current, 100ma, 125mv ldo, 3mm 3mm dfn ltc4411/ltc4412 low loss powerpath tm controller in thinsot automatic switching between dc sources, load sharing, replaces oring diodes power management ltc3405/ltc3405a 300ma (i out ), 1.5mhz, synchronous step-down 95% ef? ciency, v in : 2.7v to 6v, v out = 0.8v, i q = 20a, i sd < 1a, dc/dc converter thinsot package ltc3406/ltc3406a 600ma (i out ), 1.5mhz, synchronous step-down 95% ef? ciency, v in : 2.5v to 5.5v, v out = 0.6v, i q = 20a, i sd < 1a, dc/dc converter thinsot package ltc3411 1.25a (i out ), 4mhz, synchronous step-down 95% ef? ciency, v in : 2.5v to 5.5v, v out = 0.8v, i q = 60a, i sd < 1a, dc/dc converter ms package ltc3440 600ma (i out ), 2mhz, synchronous buck-boost 95% ef? ciency, v in : 2.5v to 5.5v, v out = 2.5v, i q = 25a, i sd < 1a, dc/dc converter ms package LTC4413 dual ideal diode in dfn 2-channel ideal diode oring, low forward on resistance, low regulated forward voltage, 2.5v v in 5.5v

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