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ltc4065l/ ltc4065lx/ltc4065l-4.1 1 4065lfb typical application features description standalone 250ma li-ion battery charger in 2 2 dfn the ltc ? 4065l is a complete constant-current/constant- voltage linear charger for single-cell lithium-ion batteries. its small size and ability to accurately regulate low charge currents make the ltc4065l especially well-suited for portable applications using low capacity rechargeable lithium-ion cells. furthermore, ltc4065l is specifically designed to work within usb power specifications. the chrg pin indicates when charge current has dropped to ten percent of its programmed value (c/10). an internal timer terminates charging according to battery manufac- turer specifications. the ltc4065l-4.1 features a constant-voltage float voltage of 4.1v. this 4.1v version of the standard ltc4065l is in- tended for back-up or high ambient temperature applications. under these conditions, a reduced float voltage will trade- off initial cell capacity for the benefit of increased capacity retention over the life of the battery. a reduced float voltage also minimizes swelling in prismatic and polymer cells. when the input supply (wall adapter or usb supply) is removed, the ltc4065l automatically enters a low current state, dropping battery drain current to less than 1a. with power applied, ltc4065l can be put into shutdown mode, reducing the supply current to less than 20a. the full-featured ltc4065l also includes automatic re- charge, low-battery charge conditioning (trickle charging) and soft-start (to limit inrush current). standalone li-ion battery charger complete charge cycle (180mah battery) ltc4065l and ltc4065lx applications n charge current programmable up to 250ma with 5% accuracy n complete linear charger in 2mm 2mm dfn package n c/10 charge current detection output n timer termination n no external mosfet, sense resistor or blocking diode required n preset float voltage with 0.6% accuracy: 4.2v for ltc4065l/ltc4065lx 4.1v for ltc4065l-4.1 n constant-current/constant-voltage operation with thermal feedback to maximize charging rate without risk of overheating n charge current monitor output for gas gauging n automatic recharge n charges single cell li-ion batteries directly from usb port n 20a supply current in shutdown mode n available without trickle charge (ltc4065lx) n tiny 6-lead (2mm 2mm) dfn package n charger for li-ion coin cell batteries n portable mp3 players, wireless headsets n bluetooth applications n multifunction wristwatches 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. protected by u.s. patents, including 6522118, 6700364. + v cc r1 510 100ma r3 2k 4065l ta01 4.2v li-ion battery v in 4.3v to 5.5v c1 1f ltc4065l chrg en bat prog gnd time (hours) 0 charge current (ma) battery voltage (v) 30 90 100 110 1 2 2.5 4065 ta02 10 70 50 20 80 0 60 40 4.3 3.5 4.1 3.3 3.9 3.7 0.5 1.5 3 3.5 4 4.5 constant current constant voltage chrg transition charge termination v cc = 5v r prog = 2k
ltc4065l/ ltc4065lx/ltc4065l-4.1 2 4065lfb pin configuration absolute maximum ratings v cc t < 1ms and duty cycle < 1% ..................C 0.3v to 7v steady state ............................................. C0.3v to 6v bat, chrg ................................................... C0.3v to 6v en , prog .........................................C0.3v to v cc + 0.3v bat short-circuit duration ............................ continuous bat pin current ...................................................275ma prog pin current .............................................1.342ma junction temperature (note 6) ............................. 125c operating temperature range (note 2)....C 40c to 85c storage temperature range ................... C65c to 125c (note 1) top view 7 dc package 6-lead (2mm 2mm) plastic dfn 4 5 6 3 2 1gnd chrg bat prog en v cc t jmax = 125c, ja = 60c/w (note 3) exposed pad (pin 7) is gnd, must be soldered to pcb order information lead free finish tape and reel part marking package description temperature range ltc4065ledc#pbf ltc4065ledc#trpbf lcbd 6-lead (2mm 2mm) plastic dfn C40c to 85c ltc4065lxedc#pbf ltc4065lxedc#trpbf lcks 6-lead (2mm 2mm) plastic dfn C40c to 85c ltc4065ledc-4.1#pbf ltc4065ledc-4.1#trpbf lggn 6-lead (2mm 2mm) plastic dfn C40c to 85c consult ltc marketing for parts specified with wider operating temperature ranges. consult ltc marketing for information on non-standard lead based finish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ ltc4065 options part number float voltage charge current range pin 5 is en or acpr ? trickle charge? ltc4065 4.2v 40ma to 750ma en yes ltc4065a 4.2v 40ma to 750ma acpr yes ltc4065-4.4 4.4v 40ma to 750ma en yes ltc4065l 4.2v 8ma to 250ma en yes ltc4065lx 4.2v 8ma to 250ma en no ltc4065l-4.1 4.1v 8ma to 250ma en yes
ltc4065l/ ltc4065lx/ltc4065l-4.1 3 4065lfb electrical characteristics the l denotes specifications which apply over the full operating temperature range, otherwise specifications are t a = 25c. v cc = 5v, v bat = 3.8v, v en = 0v unless otherwise speci? ed. (note 2) symbol parameter conditions min typ max units v cc v cc supply voltage (note 4) l 3.75 5.5 v i cc quiescent v cc supply current v bat = 4.5v (forces i bat and i prog = 0) l 120 250 a i ccms v cc supply current in shutdown v en = 5v l 20 40 a i ccuv v cc supply current in undervoltage lockout v cc < v bat , v cc = 3.5v, v bat = 4v l 611 a v float v bat regulated output voltage i bat = 2ma i bat = 2ma, 0c < t a < 85c i bat = 2ma (ltc4065l-4.1) i bat = 2ma, 0c < t a < 85c (ltc4065l-4.1) 4.175 4.158 4.075 4.058 4.2 4.2 4.1 4.1 4.225 4.242 4.125 4.142 v v v v i bat bat pin current r prog = 13.3k (0.1%), current mode r prog = 1.33k (0.1%), current mode l l 13.5 148 15.5 155 17.5 162 ma ma i bms battery drain current in shutdown mode v en = v cc l C1 0 1 a i buv battery drain current in undervoltage lockout v cc = 3.5v, v bat = 4v l 014 a v uvlo v cc undervoltage lockout voltage v cc rising v cc falling l l 3.4 2.8 3.6 3.0 3.8 3.2 v v v prog prog pin voltage r prog = 1.33k, i prog = 0.75ma r prog = 13.3k, i prog = 75a l l 0.98 0.98 1 1 1.02 1.02 v v v asd automatic shutdown threshold voltage (v cc C v bat ), v cc low to high (v cc C v bat ), v cc high to low 60 15 80 30 100 45 mv mv v msh manual shutdown high voltage v en rising 1 v v msl manual shutdown low voltage v en falling 0.6 v r en en pin input resistance l 0.9 1.5 3.3 m t ss soft-start time 170 s i trkl trickle charge current v bat = 2v, r prog = 1.33k (0.1%) (note 7) 13 15.5 18 ma v trkl trickle charge threshold voltage v bat rising (note 7) l 2.7 2.9 3.05 v v trhys trickle charge hysteresis voltage (note 7) 90 mv v rechrg recharge battery threshold voltage v float C v rechrg , 0c < t a < 85c 70 100 130 mv v uvcl1 v uvcl2 (v cc C v bat ) undervoltage current limit i bat = 90%, r prog = 2k, programmed charge current i bat = 10%, r prog = 2k, programmed charge current 150 80 190 125 300 150 mv mv t timer termination timer l 3 4.5 6 hrs recharge time l 1.5 2.25 3 hrs low-battery trickle charge time v bat = 2.5v l 0.75 1.125 1.5 hrs v chrg chrg pin output low voltage i chrg = 5ma l 60 105 mv
ltc4065l/ ltc4065lx/ltc4065l-4.1 4 4065lfb 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 ltc4065l is tested under pulsed load conditions such that t j t a . the ltc4065l is guaranteed to meet performance specifica- tions from 0c to 70c. specifications over the C40c to 85c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: failure to solder the exposed backside of the package to the pc board ground plane will result in a thermal resistance much higher than rated. electrical characteristics the l denotes specifications which apply over the full operating temperature range, otherwise specifications are t a = 25c. v cc = 5v, v bat = 3.8v, v en = 0v unless otherwise speci? ed. (note 2) symbol parameter conditions min typ max units i chrg chrg pin input current v bat = 4.5v, v chrg = 5v l 01 a i c/10 end of charge indication current level r prog = 1.33k (note 5) l 0.08 0.095 0.11 ma/ma t lim junction temperature in constant temperature mode 115 c r on power fet on resistance (between v cc and bat) i bat = 150ma 1.5 f badbat defective battery detection chrg pulse frequency 2hz d badbat defective battery detection chrg pulse frequency duty ratio 75 % note 4: although the ltc4065l functions properly at 3.75v input, full charge current requires an input voltage greater than the desired final bat- tery voltage per the v uvcl1 specification. note 5: i c/10 is expressed as a fraction of measured full charge current with indicated prog resistor. note 6: this ic includes overtemperature protection that is intended to protect the device during momentary overload conditions. junction temperature will exceed 125c when overtemperature protection is active. continuous operation above the specified maximum operating junction temperature may impair device reliability. note 7: this parameter is not applicable to the ltc4065lx.
ltc4065l/ ltc4065lx/ltc4065l-4.1 5 4065lfb typical performance characteristics battery regulation (float) voltage vs battery charge current battery regulation (float) voltage vs temperature battery regulation (float) voltage vs supply voltage charge current vs supply voltage (constant current mode) charge current vs battery voltage charge current vs temperature with thermal regulation (constant current mode) prog pin voltage vs temperature (constant current mode) prog pin voltage vs charge current power fet on resistance vs temperature i bat (ma) 0 v float (v) 4.12 4.14 4.16 150 250 4065l g01 4.10 4.08 4.06 50 100 200 4.18 4.22 4.20 4.24 v cc = 5v t a = 25c r prog = 800 ltc4065l ltc4065l-4.1 temperature (c) C50 v float (v) 4.22 25 4065l g02 4.14 4.10 C25 0 50 4.08 4.06 4.24 4.20 4.18 4.16 4.12 75 100 ltc4065l ltc4065l-4.1 supply voltage (v) 4 v float (v) 4.16 4.18 4.20 6 4065l g03 4.12 4.14 4.10 4.06 4.5 5 5.5 4.08 4.24 4.22 t a = 25c i bat = 2ma r prog = 800 ltc4065l ltc4065l-4.1 supply voltage (v) 4 0 5 10 20 25 30 i bat (ma) 15 4.5 5 5.5 6 4065l g04 r prog = 13.3k v bat = 3.8v t a = 25c v bat (v) 0 0 i bat (ma) 50 100 150 200 250 300 1234 4065l g05 5 v cc = 5v t a = 25c r prog = 800 ltc4065l-4.1 ltc4065l temperature (c) C50 0 i bat (ma) 50 100 150 200 050 100 150 4065l g06 250 300 thermal control loop in operation v cc = 5v v bat = 3.8v r prog = 800 temperature (c) C50 v prog (v) 1.01 1.02 25 75 4065l g07 1.00 C25 0 50 100 0.99 0.98 v cc = 5v v bat = 3.8v r prog = 13.3k i bat (ma) 0 0 v prog (v) 0.2 0.4 0.6 0.8 1.0 1.2 50 100 150 200 4065l g08 250 v cc = 5v t a = 25c r prog = 800 temperature (c) C50 1.0 r ds () 1.2 1.4 1.6 1.8 2.0 C25 02550 4065l g09 75 100 v cc = 4v i bat = 150ma
ltc4065l/ ltc4065lx/ltc4065l-4.1 6 4065lfb typical performance characteristics chrg pin output low voltage vs temperature manual shutdown threshold voltage vs temperature manual shutdown supply current vs temperature en pin current trickle charge current vs supply voltage (4065l and 4065l-4.1) trickle charge current vs temperature (4065l and 4065l-4.1) undervoltage lockout threshold voltage vs temperature timer accuracy vs temperature timer accuracy vs supply voltage temperature (c) C50 2.50 v cc (v) 2.75 3.00 3.25 3.50 4.00 C25 025 rise fall 50 4065l g10 75 100 3.75 temperature (c) C50 C25 0.5 v ms (v) 0.7 1.0 0 50 75 4065l g11 0.6 0.9 0.8 25 100 fall rise temperature (c) C50 0 i ccms (a) 10 20 30 40 C25 0 25 50 4065l g12 75 100 v cc = 5v v en = 5v v en (v) 2 i en (a) 1.5 2.0 2.5 3.5 4.5 4065l g13 1.0 0.5 0 2.5 3 4 3.0 3.5 4.0 5 v cc = 5v t a = 25c supply voltage (v) 4 0 i bat (ma) 5 10 15 20 25 30 4.5 5 5.5 6 4065l g14 v bat = 2v t a = 25c r prog = 800 r prog = 13.3k temperature (c) C50 i bat (ma) 20 25 30 25 75 4065l g15 15 10 C25 0 50 100 5 0 v cc = 5v v bat = 2v r prog = 800 r prog = 13.3k temperature (c) C50 80 100 140 25 75 4065l g16 60 40 C25 0 50 100 20 0 120 v chrg (mv) v cc = 5v i chrg = 5ma temperature (c) C50 timer accuracy (%) C4 C3 C2 25 75 4065l g18 C5 C6 C7 C25 0 50 C1 0 1 100 v cc = 5v supply voltage (v) 4 timer accuracy (%) 0 1.0 6 4065l g19 C1.0 C2.0 4.5 5 5.5 2.0 C0.5 0.5 C1.5 1.5 t a = 25c
ltc4065l/ ltc4065lx/ltc4065l-4.1 7 4065lfb pin functions gnd (pin 1, exposed pad pin 7): ground. the exposed pad must be soldered to the pcb ground to provide both electrical contact and rated thermal performance. chrg (pin 2): open-drain charge status output. the charge status indicator pin has three states: pull-down, pulse at 2hz and high impedance state. this output can be used as a logic interface or as an led driver. when the battery is being charged, the chrg pin is pulled low by an internal n-channel mosfet. when the charge current drops to 10% of the full-scale current, the chrg pin is forced to a high impedance state. if the battery voltage remains below 2.9v for one quarter of the charge time, the battery is considered defective and the chrg pin pulses at a frequency of 2hz. bat (pin 3): charge current output. provides charge cur- rent to the battery and regulates the final float voltage (4.2v for ltc4065l/ltc4065lx and 4.1v for ltc4065l-4.1). an internal precision resistor divider on this pin sets the float voltage and is disconnected in shutdown mode. v cc (pin 4): positive input supply voltage. this pin pro- vides power to the charger. v cc can range from 3.75v to 5.5v. this pin should be bypassed with at least a 1f capacitor. when v cc is within 32mv of the bat pin volt- age, the ltc4065l enters shutdown mode, dropping i bat to about 1a. en (pin 5): enable input pin. pulling this pin above the manual shutdown threshold (v ms is typically 0.82v) puts the ltc4065l in shutdown mode. in shutdown mode, the ltc4065l has less than 20a supply current and less than 1a battery drain current. enable is the default state, but the pin should be tied to gnd if unused. prog (pin 6): charge current program and charge cur- rent monitor pin. connecting a 1% resistor, r prog , to ground programs the charge current. when charging in constant-current mode, this pin servos to 1v. in all modes, the voltage on this pin can be used to measure the charge current using the following formula: i bat = v prog r prog ? 205 floating the prog pin sets the charge current to zero.
ltc4065l/ ltc4065lx/ltc4065l-4.1 8 4065lfb simplified block diagram ? + ? + ?+ ?+ 2 + mp m2 1 m1 205 v cc v cc r1 r2 enable r3 r4 r enb r5 2.9v chrg 6 trickle charge disabled on the ltc4065lx 1 gnd 4056l f01 r prog bat 1v prog 0.82v c/10 c1 ? + ta t die 115c 0.1v 1.2v shutdown d3 0.1v d2 3.6v d1 1.2v ?+ ref ca ma lobat 5 en ? + uvlo 3 4 bat logic counter oscillator shutdown charge control ?+ c2 va prog figure 1. ltc4065l block diagram
ltc4065l/ ltc4065lx/ltc4065l-4.1 9 4065lfb operation the ltc4065l is a linear battery charger designed primar- ily for charging single cell lithium-ion batteries. featuring an internal p-channel power mosfet, the charger uses a constant-current/constant-voltage charge algorithm with programmable current. charge current can be programmed up to 250ma with a final float voltage accuracy of 0.6%. the chrg open-drain status output indicates if c/10 has been reached. no blocking diode or external sense resis- tor is required; thus, the basic charger circuit requires only two external components. an internal termination timer and trickle charge low-battery conditioning adhere to battery manufacturer safety guidelines (note: the ltc4065lx does not include this trickle charge feature). furthermore, the ltc4065l is capable of operating from a usb power source. an internal thermal limit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115c. this feature protects the ltc4065l 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 ltc4065l or external components. another benefit of the ltc4065l thermal limit is that charge current can be set according to typical, not worst-case, ambient temperatures for a given application with the assurance that the charger will automatically reduce the current in worst-case conditions. the charge cycle begins when the following conditions are met: the voltage at the v cc pin exceeds 3.6v and ap- proximately 80mv above the bat pin voltage, a program resistor is present from the prog pin to ground and the en pin is pulled below the shutdown threshold (typically 0.82v). if the bat pin voltage is below 2.9v, the charger goes into trickle charge mode, charging the battery at one-tenth the programmed charge current to bring the cell voltage up to a safe level for charging (note: the ltc4065lx does not include this trickle charge feature). if the bat pin volt- age is above 4.1v for ltc4065l/ltc4065lx or 4.0v for ltc4065l-4.1, the charger will not charge the battery as the cell is near full capacity. otherwise, the charger goes into the fast charge constant-current mode. when the bat pin approaches the final float voltage (4.2v for ltc4065l/ltc4065lx or 4.1v for ltc4065l-4.1), the ltc4065l enters constant-voltage mode and the charge current begins to decrease. when the current drops to 10% of the full-scale charge current, an internal compara- tor turns off the n-channel mosfet on the chrg pin and the pin assumes a high impedance state. an internal timer sets the total charge time, t timer (typi- cally 4.5 hours). when this time elapses, the charge cycle terminates and the chrg pin assumes a high impedance state. to restart the charge cycle, remove the input voltage and reapply it or momentarily force the en pin above v ms (typically 0.82v). the charge cycle will automatically restart if the bat pin voltage falls below v rechrg (typically 4.1v). when the input voltage is not present, the battery drain current is reduced to less than 4a. the ltc4065l can also be shut down by pulling the en pin above the shutdown threshold voltage. this reduces input quiescent current to less than 20a and battery drain current to less than 1a. programming charge current the charge current is programmed using a single resistor from the prog pin to ground. the battery charge current is 205 times the current out of the prog pin. the program resistor and the charge current are calculated using the following equations: r prog = 205 ? 1v i bat ,i bat = 205v r prog the charge current out of the bat pin can be determined at any time by monitoring the prog pin voltage and using the following equation: i bat = v prog r prog ?205
ltc4065l/ ltc4065lx/ltc4065l-4.1 10 4065lfb operation undervoltage lockout (uvlo) an internal undervoltage lockout circuit monitors the input voltage and keeps the charger in undervoltage lockout until v cc rises above 3.6v and approximately 80mv above the bat pin voltage. the 3.6v uvlo circuit has a built-in hys- teresis of approximately 0.6v and the automatic shutdown threshold has a built-in hysteresis of approximately 50mv. during undervoltage lockout conditions, maximum battery drain current is 4a and maximum supply current is 11a. shutdown mode the ltc4065l can be disabled by pulling the en pin above the shutdown threshold (approximately 0.82v). in shutdown mode, the battery drain current is reduced to less than 1a and the supply current to about 20a. timer and recharge the ltc4065l has an internal termination timer that starts when an input voltage greater than the undervolt- age lockout threshold is applied to v cc , or when leaving shutdown the battery voltage is less than the recharge threshold. at power-up or when exiting shutdown, if the battery volt- age is less than the recharge threshold, the charge time is set to 4.5 hours. if the battery voltage is greater than the recharge threshold at power-up or when exiting shutdown, the timer will not start and charging is prevented since the battery is at or near full capacity. once the charge cycle terminates, the ltc4065l continu- ously monitors the bat pin voltage using a comparator with a 2ms filter time. when the average battery voltage falls 100mv below the float voltage (which corresponds to 80% to 90% battery capacity), a new charge cycle is initiated and a 2.25 hour timer begins. this ensures that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle initiations. the chrg output assumes a strong pull-down state during recharge cycles until c/10 is reached when it transitions to a high impendance state. trickle charge and defective battery detection at the beginning of a charge cycle, if the battery voltage is low (below 2.9v), the charger goes into trickle charge, reducing the charge current to 10% of the full-scale cur- rent (note: the ltc4065lx has full charge current at low-battery voltage). if the low-battery voltage persists for one quarter of the total time (1.125 hour), the battery is assumed to be defective, the charge cycle is terminated and the chrg pin output pulses at a frequency of 2hz with a 75% duty cycle. if for any reason the battery voltage rises above 2.9v, the charge cycle will be restarted. to restart the charge cycle (i.e., when the defective battery is replaced with a discharged battery), simply remove the input voltage and reapply it or temporarily pull the en pin above the shutdown threshold. chrg status output pin the charge status indicator pin has three states: pull- down, pulse at 2hz (see trickle charge and defective battery detection) and high impedance. the pull-down state indicates that the ltc4065l is in a charge cycle. a high impedance state indicates that the charge current has dropped below 10% of the full-scale current or the ltc4065l is disabled. figure 2 shows the chrg status under various conditions.
ltc4065l/ ltc4065lx/ltc4065l-4.1 11 4065lfb operation charge current soft-start and soft-stop the ltc4065l 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 170s. likewise, internal circuitry slowly ramps the charge current 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. constant-current/constant-voltage/ constant-temperature the ltc4065l use a unique architecture to charge a bat- tery in a constant-current, constant-voltage and constant- temperature fashion. figure 1 shows a simplified block diagram of the ltc4065l. three of the amplifier feedback loops shown control the constant-current, ca, constant- voltage, va, and constant-temperature, ta modes. a fourth amplifier feedback loop, ma, is used to increase the output impedance of the current source pair; m1 and m2 (note that m1 is the internal p-channel power mosfet). it ensures that the drain current of m1 is exactly 205 times greater than the drain current of m2. amplifiers ca and va are used in separate feedback loops to force the charger into constant-current or constant- voltage mode, respectively. diodes d1 and d2 provide priority to either the constant-current or constant-voltage loop, whichever is trying to reduce the charge current the most. the output of the other amplifier saturates low which effectively removes its loop from the system. when in constant-current mode, ca servos the voltage at the prog pin to be precisely 1v. va servos its inverting input to an internal reference voltage when in constant-voltage mode and the internal resistor divider, made up of r1 and r2, ensures that the battery voltage is maintained at 4.2v for ltc4065l/ltc4065lx or 4.1v for ltc4065l-4.1. the prog pin voltage gives an indication of the charge current during constant-voltage mode as discussed in program- ming charge current. the transconductance amplifier, ta, limits the die tempera- ture to approximately 115c when in constant-temperature mode. diode d3 ensures that ta does not affect the charge current when the die temperature is below approximately 115c. the prog pin voltage continues to give an indica- tion of the charge current. in typical operation, the charge cycle begins in constant- current mode with the current delivered to the battery equal to 205v/r prog . if the power dissipation of the ltc4065l results in the junction temperature approaching 115c, the amplifier (ta) will begin decreasing the charge current to limit the die temperature to approximately 115c. as the battery voltage rises, the ltc4065l either returns to constant-current mode or enters constant-voltage mode straight from constant-temperature mode. regardless of mode, the voltage at the prog pin is proportional to the current delivered to the battery.
ltc4065l/ ltc4065lx/ltc4065l-4.1 12 4065lfb is en > shutdown threshold? enable chrg high impedance shutdown mode if v cc > 3.6v and v cc > v bat + 80mv? uvlo uvlo mode 1/10 full charge current chrg strong pull-down trickle charge mode* full charge current chrg strong pull-down fast charge mode is v bat < 2.9v? defective battery is v bat < 4.1v? (ltc4065l/ltc4065lx) is v bat < 4.0v? (ltc4065l-4.1) recharge no charge current chrg pulses (2hz) bad battery mode full charge current chrg strong pull-down recharge mode no charge current chrg high impedance standby mode chrg high impedance no yes yes yes no no 4065l f02 v bat 2.9v 1/4 charge cycle (1.125 hours) v cc < 3v or en > shdn threshold charge cycle (4.5 hours) 1/2 charge cycle (2.25 hours) 2.9v < v bat < 4.1v (ltc4065l/ltc4065lx) 2.9v < v bat < 4.0v (ltc4065l-4.1) v bat > 4.1v (ltc4065l/ltc4065lx) v bat > 4.0v (ltc4065l-4.1) yes no power on *ltc4065l and ltc4065l-4.1 only; ltc4065lx has full charge current. operation figure 2. state diagram of ltc4065l operation
ltc4065l/ ltc4065lx/ltc4065l-4.1 13 4065lfb undervoltage charge current limiting (uvcl) the ltc4065l includes undervoltage charge (v uvcl1 ) current limiting that prevents full charge current until the input supply voltage reaches approximately 200mv above the battery voltage. this feature is particularly useful if the ltc4065l is powered from a supply with long leads (or any relatively high output impedance). for example, usb-powered systems tend to have highly variable source impedances (due primarily to cable quality and length). a transient load combined with such imped- ance can easily trip the uvlo threshold and turn the charger off unless undervoltage charge current limiting is implemented. consider a situation where the ltc4065l is operating under normal conditions and the input supply voltage begins to droop (e.g., an external load drags the input supply down). if the input voltage reaches v bat + v uvcl1 (approximately 220mv above the battery voltage), un- dervoltage charge current limiting will begin to reduce the charge current in an attempt to maintain v uvcl1 between the v cc input and the bat output of the ic. the ltc4065l will continue to operate at the reduced charge current until the input supply voltage is increased or volt- age mode reduces the charge current further. applications information usb and wall adapter power although the ltc4065l allows charging from a usb port, a wall adapter can also be used to charge li-ion batteries. figure 3 shows an example of how to combine wall adapter and usb power inputs. a p-channel mosfet, mp1, is used to prevent back conducting into the usb port when a wall adapter is present and schottky diode, d1, is used to prevent usb power loss through the 1k pull-down resistor. stability considerations the ltc4065l contains two control loops: constant-voltage and constant-current. the constant-voltage loop is stable without any compensation when a battery is connected with low impedance leads. excessive lead length, however, may add enough series inductance to require a bypass capacitor of at least 1f from bat to gnd. furthermore, a 4.7f capacitor with a 0.2 to 1 series resistor from bat to gnd is required to keep ripple voltage low when the battery is disconnected. high value capacitors with very low esr (especially ce- ramic) may reduce the constant-voltage loop phase margin. ceramic capacitors up to 22f may be used in parallel with a battery, but larger ceramics should be decoupled with 0.2 to 1 of series resistance. v cc mp1 1k 800 3 i bat 4 6 li-ion battery system load 4065l f03 ltc4065l bat usb power 5v wall adapter prog + d1 figure 3. combining wall adapter and usb power
ltc4065l/ ltc4065lx/ltc4065l-4.1 14 4065lfb applications information in constant-current mode, the prog pin is in the feedback loop, not the battery. because of the additional pole created by the prog pin capacitance, capacitance on this pin must be kept to a minimum. with no additional capacitance on the prog pin, the charger is stable with program resistor values as high as 25k. however, additional capacitance on this node reduces the maximum allowed program resis- tor. the pole frequency at the prog pin should be kept above 100khz. therefore, if the prog pin is loaded with a capacitance, c prog , the following equation should be used to calculate the maximum resistance value for r prog : r prog 1 2 ?10 5 ?c prog average, rather than instantaneous, battery current may be of interest to the user. for example, if a switching power supply operating in low current mode is connected in parallel with the battery, the average current being pulled out of the bat pin is typically of more interest than the instantaneous current pulses. in such a case, a simple rc filter can be used on the prog pin to measure the average battery current as shown in figure 4. a 10k resistor has been added between the prog pin and the filter capacitor to ensure stability. power dissipation due to the low charge currents, it is unlikely that the ltc4065l will reduce charge current through thermal feedback. nonetheless, the ltc4065l power dissipation can be approximated by: p d = (v cc C v bat ) ? i bat where 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. it is not necessary to perform any worst-case power dissipation scenarios because the ltc4065l will automatically reduce the charge current to maintain the die temperature at approximately 115c. however, the approximate ambient temperature at which the thermal feedback begins to protect the ic is: t a = 115c C p d ? ja t a = 115c C (v cc C v bat ) ? i bat ? ja 4065l f04 c filter charge current monitor circuitry r prog ltc4065l prog gnd 10k figure 4. isolating capacitive load on the prog pin and filtering
ltc4065l/ ltc4065lx/ltc4065l-4.1 15 4065lfb applications information example: consider an ltc4065l operating from a 5.5v wall adapter providing 250ma to a 3v li-ion battery. the ambient temperature above which the ltc4065l will begin to reduce the 250ma charge current is approximately: t a = 115c C (5.5v C 3v) ? (250ma) ? 60c/w t a = 115c C 0.625w ? 60c/w = 115c C 37.5c t a = 77.5c charging at such high ambient temperatures is not recom- mended by battery manufacturers. furthermore, the voltage at the prog pin will change proportionally with the charge current as discussed in the programming charge current section. it is important to remember that ltc4065l applications do not need to be designed for worst-case thermal conditions since the ic will automatically reduce power dissipation when the junction temperature reaches ap- proximately 115c. board layout considerations in order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the ltc4065l package is soldered to the pc board ground. correctly soldered to a 2500mm 2 double-sided 1 oz. copper board the ltc4065l has a thermal resistance of approximately 60c/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 60c/w. 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. for more information, refer to application note 88.
ltc4065l/ ltc4065lx/ltc4065l-4.1 16 4065lfb package description please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. dc package 6-lead plastic dfn (2mm 2mm) (reference ltc dwg # 05-08-1703) 2.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (wccd-2) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.38 0.05 bottom viewexposed pad 0.56 0.05 (2 sides) 0.75 0.05 r = 0.115 typ 1.37 0.05 (2 sides) 1 3 64 pin 1 bar top mark (see note 6) 0.200 ref 0.00 C 0.05 (dc6) dfn 1103 0.25 0.05 0.50 bsc 0.25 0.05 1.42 0.05 (2 sides) recommended solder pad pitch and dimensions 0.61 0.05 (2 sides) 1.15 0.05 0.675 0.05 2.50 0.05 package outline 0.50 bsc pin 1 chamfer of exposed pad
ltc4065l/ ltc4065lx/ltc4065l-4.1 17 4065lfb 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. revision history rev date description page number b 05/12 added new part number ltc4065l-4.1 added options table & updated order information table clarified note 2 testing conditions clarified state diagram throughout 2 4 12 (revision history begins at rev b)
ltc4065l/ ltc4065lx/ltc4065l-4.1 18 4065lfb linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2005 lt 0512 rev b ? printed in the usa related parts 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 ltc4050 lithium-ion linear battery charger controller features preset voltages, c/10 charger detection and programmable timer, input power good indication, thermistor interface ltc4054 standalone linear li-ion battery charger with integrated pass transistor in thinsot thermal regulation prevents overheating, c/10 termination, c/10 indicator, up to 800ma charge current ltc4054l standalone linear li-ion battery charger with integrated pass transistor in thinsot low current version of ltc4054, charge current up to 150ma ltc4057 lithium-ion linear battery charger up to 800ma charge current, thermal regulation, thinsot package ltc4059/ ltc4059a 900ma linear lithium-ion battery charger 2mm 2mm dfn package, thermal regulation, charge current monitor output. a version has acpr function ltc4061 standalone li-ion charger with thermistor interface 4.2v, 0.35% float voltage, up to 1a charge current, 3mm 3mm dfn ltc4061-4.4 standalone li-ion charger with thermistor interface 4.4v (max), 0.4% float voltage, up to 1a charge current, 3mm 3mm dfn ltc4062 standalone linear li-ion battery charger with micropower comparator 4.2v, 0.35% float voltage, up to 1a charge current, 3mm 3mm dfn ltc4063 li-ion charger with linear regulator up to 1a charge current, 100ma, 125mv ldo, 3mm 3mm dfn ltc4065/ ltc4065a standalone li-ion battery chargers 4.2v, 0.6% float voltage, up to 750ma charge current, 2mm 2mm dfn; a version has acpr function power management ltc3405/ ltc3405a 300ma (i out ), 1.5mhz, synchronous step-down dc/dc converter 95% efficiency, v in : 2.7v to 6v, v out = 0.8v, i q = 20a, i sd < 1a, thinsot package LTC3406/ LTC3406a 600ma (i out ), 1.5mhz, synchronous step-down dc/dc converter 95% efficiency, v in : 2.5v to 5.5v, v out = 0.6v, i q = 20a, i sd < 1a, thinsot package ltc3411 1.25a (i out ), 4mhz, synchronous step-down dc/dc converter 95% efficiency, v in : 2.5v to 5.5v, v out = 0.8v, i q = 60a, i sd < 1a, ms package ltc3440 600ma (i out ), 2mhz, synchronous buck-boost dc/dc converter 95% efficiency, v in : 2.5v to 5.5v, v out = 2.5v, i q = 25a, i sd < 1a, ms package ltc4411/ltc4412 low loss powerpath tm controller in thinsot automatic switching between dc sources, load sharing, replaces oring diodes 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 thinsot and powerpath are trademarks of linear technology corporation.

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