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ltc4054l-4.2 1 4054l42fa typical a pplica t ion fea t ures descrip t ion 150ma standalone linear li-ion battery charger in thinsot the ltc ? 4054l is a complete, constant-current/constant- voltage linear charger for single cell lithium-ion batteries. its small size and ability to regulate low charge currents make the ltc4054l especially well-suited for portable ap - plications using low capacity rechargeable lithium-ion coin cells. furthermore, the ltc4054l is specifically designed to work within usb power specifications. no external sense resistor is needed, and no blocking diode is required due to the internal mosfet architecture. thermal feedback regulates the charge current to eliminate thermal overdesign. the charge voltage is fixed at 4.2v, and the charge current can be programmed externally with a single resistor. the ltc4054l automatically terminates a charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. when the input supply (wall adapter or usb supply) is removed, the ltc4054l automatically enters a low current state, dropping the battery drain current to less than 2a. the ltc4054l can be put into shutdown mode, reducing the supply current to 25a. other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage. l , lt, ltc, ltm, linear technology and the linear logo are registered trademarks and thinsot is a trademark of linear technology corporation. all other trademarks are the property of their respective owners. *protected by u.s. patents including 6,522,118. a pplica t ions n programmable charge current range: 10ma to 150ma n no external mosfet, sense resistor or blocking diode required n complete linear charger in thinsot? package for single cell/coin cell lithium-ion batteries n constant-current/constant-voltage operation with thermal regulation* to maximize charge rate without risk of overheating n charges single cell li-ion batteries directly from usb port n preset 4.2v charge voltage with 1% accuracy n charge current monitor output for gas gauging* n automatic recharge n charge status output pin n c/10 charge termination n 25a max supply current in shutdown mode n 2.9v trickle charge threshold n soft-start limits inrush current n available in a 5-lead low profile (1mm) sot -23 package n charger for li-ion coin cell batteries n portable mp3 players, wireless headsets n bluetooth applications n multifunction wristwatches 90ma li-ion single coin cell charger complete charge cycle (130mah battery) v cc 1.69k 4.2v coin cell li-ion battery 4054l42 ta01 ltc4054l-4.2 1f v in 4.5v to 6.5v bat 4 3 90ma 5 2 prog gnd time (hours) 0 charge current (ma) 100 90 80 70 60 50 40 30 20 10 0 battery voltage (v) 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 3.5 3.4 0.5 1.0 1.25 2.25 4054l42 ta01b 0.25 0.75 1.5 1.75 2.0 constant current constant voltage v cc = 5v ja = 130c/w r prog = 1.69k t a = 25c
ltc4054l-4.2 2 4054l42fa p in c on f igura t ion a bsolu t e maxi m u m r a t ings input supply voltage (v cc ) ........................ C0 .3v to 10v prog ............................................... C 0.3v to v cc + 0.3v chrg ......................................................... C 0.3v to 10v bat .............................................................. C0 .3v to 7v bat short-circuit duration ........................... c ontinuous bat pin current .................................................. 20 0ma prog pin current ................................................. 1. 5ma maximum junction temperature .......................... 1 25c operating temperature range (note 2).... C40c to 85c storage temperature range .................. C 65c to 125c lead temperature (soldering, 10 sec) ................... 3 00c (note 1) chrg 1 gnd 2 top view s5 package 5-lead plastic tsot-23 bat 3 5 prog 4 v cc t jmax = 125c, ja = 80c/w to 150c/w depending on pcb board layout (note 3) o r d er i n f or m a t ion lead free finish tape and reel part marking package description temperature range ltc4054les5-4.2#pbf ltc4054les5-4.2#trpbf lta fa 5-lead plastic tsot-23 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/ e lec t rical c harac t eris t ics symbol parameter conditions min typ max units v cc supply voltage l 4.25 6.5 v i cc supply current charge mode (note 4), r prog = 1k standby mode (charge terminated) shutdown mode (r prog not connected, v cc < v bat , or v cc < v uv ) l l l 1200 200 25 2000 500 50 a a a v float regulated output (float) voltage 0c t a 85c, i bat = 40ma 4.158 4.2 4.242 v i bat bat pin current r prog = 15k, current mode r prog = 1k, current mode standby mode, v bat = 4.2v shutdown mode (r prog not connected) sleep mode, v cc = 0v l l l 9.3 142.5 0 10 150 C2.5 1 1 10.7 157.5 C6 2 2 ma ma a a a i trikl trickle charge current v bat < v trikl , r prog = 1k (i bat = 150ma) l 5 15 25 ma v trikl trickle charge threshold voltage r prog = 15k, v bat rising 2.8 2.9 3 v v trhys trickle charge hysteresis voltage r prog = 15k 60 80 110 mv v uv v cc undervoltage lockout threshold voltage from v cc low to high l 3.7 3.8 3.92 v v uvhys v cc undervoltage lockout hysteresis voltage l 150 200 300 mv v msd manual shutdown threshold voltage prog pin rising prog pin falling l l 1.15 0.9 1.21 1.0 1.30 1.1 v v v asd v cc C v bat lockout threshold voltage v cc from low to high v cc from high to low 70 5 100 30 140 50 mv mv the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. v cc = 5v, unless otherwise noted.
ltc4054l-4.2 3 4054l42fa e lec t rical c harac t eris t ics 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 ltc4054le-4.2 is guaranteed to meet performance specifications 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: see thermal considerations. note 4: supply current includes prog pin current (1ma) but does not include any current delivered to the battery through the bat pin. note 5: i term is expressed as a fraction of measured full charge current with indicated prog resistor. symbol parameter conditions min typ max units i term c/10 termination current threshold r prog = 15k (i bat = 10ma) (note 5) r prog = 1k (i bat = 150ma) (note 5) l l 0.085 0.088 0.10 0.10 0.115 0.112 ma/ma ma/ma v prog prog pin voltage r prog = 1k, current mode l 0.93 1 1.07 v i chrg chrg pin weak pull-down current v chrg = 5v 8 20 35 a v chrg chrg pin output low voltage i chrg = 5ma 0.35 0.6 v ?v rechrg recharge battery hysteresis voltage v float C v rechrg 100 150 200 mv t lim junction temperature in constant temperature mode 120 c r on power fet on resistance (between v cc and bat ) 1.5 t ss soft-start time i bat = 0 to i bat =150v/r prog 100 s t recharge recharge comparator filter time v bat high to low 0.75 2 4.5 ms t term termination comparator filter time i bat drops below i chg /10 400 1000 2500 s i prog prog pin pull-up current 1.5 3 5 a the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. v cc = 5v, unless otherwise noted. typical p er f or m ance c harac t eris t ics prog pin voltage vs supply voltage (constant current mode) prog pin voltage vs temperature (constant current mode) charge current vs prog pin voltage v cc (v) 4 v prog (v) 0.9975 1.0000 1.0025 5.5 6.5 4054l g01 0.9950 0.9925 0.9900 4.5 5 6 1.0050 1.0075 1.0100 7 v cc = 5v v bat = 4v t a = 25c r prog = 1k r prog = 15k temperature (c) ?50 v prog (v) 0.9975 1.0000 1.0025 25 75 4054l g02 0.9950 0.9925 0.9900 ?25 0 50 1.0050 1.0075 1.0100 100 v cc = 5v v bat = 4v r prog = 1k v prog (v) 0 0 i bat (ma) 30 60 90 120 150 180 0.25 0.5 0.75 1 4054l g03 1.25 v cc = 5v r prog = 1k t a = 25c
ltc4054l-4.2 4 4054l42fa typical p er f or m ance c harac t eris t ics regulated output (float) voltage vs charge current regulated output (float) voltage vs temperature regulated output (float) voltage vs supply voltage chrg pin i-v curve (strong pull-down state) chrg pin current vs temperature (strong pull-down state) chrg pin i-v curve (weak pull-down state) prog pin pull-up current vs temperature and supply voltage prog pin current vs prog pin voltage (pull-up current) prog pin current vs prog pin voltage (clamp current) temperature (c) ?50 i prog (a) 3.3 3.5 3.7 25 75 4054l g04 3.1 2.9 ?25 0 50 100 125 2.7 2.5 v bat = 4.3v v prog = 0v v cc = 6.5v v cc = 4.2v v prog (v) 2.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 2.3 2.5 4054l g05 2.1 2.2 2.4 2.6 i prog (a) v cc = 5v v bat = 4.3v t a = 25c v prog (v) 2 i prog (a) ?50 3.5 4054l g06 ?200 ?300 2.5 3 4 ?350 ?400 0 ?100 ?150 ?250 4.5 5 5.5 v cc = 5v v bat = 4.3v t a = 25c i bat (ma) 0 4.14 v float (v) 4.16 4.18 4.20 4.22 4.26 30 60 90 120 4054l g07 150 180 4.24 v cc = 5v r prog = 600 t a = 25c temperature (c) ?50 4.185 v float (v) 4.190 4.195 4.200 4.205 4.215 ?25 0 25 50 4054l g08 75 100 4.210 v cc = 5v r prog = 1k v cc (v) 4 4.185 v float (v) 4.190 4.195 4.200 4.205 4.215 4.5 5 5.5 6 4054l g09 6.5 7 4.210 r prog = 1k t a = 25c v chrg (v) 0 1 0 i chrg (ma) 10 25 2 4 5 4054l g10 5 20 15 3 6 7 v cc = 5v v bat = 4v t a = 25c temperature (c) ? 50 i chrg (ma) 18 25 4054l g11 12 8 ? 25 0 50 6 4 20 16 14 10 75 100 125 v cc = 5v v bat = 4v v chrg = 1v v chrg (v) 0 16 18 22 3 5 4054l g12 14 12 1 2 4 6 7 10 8 20 i chrg (a) v cc = 5v v bat = 4.3v t a = 25c
ltc4054l-4.2 5 4054l42fa typical p er f or m ance c harac t eris t ics trickle charge threshold vs temperature charge current vs battery voltage charge current vs supply voltage charge current vs ambient temperature recharge voltage threshold vs temperature power fet on resistance vs temperature chrg pin current vs temperature (weak pull-down state) trickle charge current vs temperature trickle charge current vs supply voltage temperature (c) ?50 10 i chrg (a) 13 16 19 22 28 ?25 0 25 50 4054l g13 75 100 25 v cc = 5v v bat = 4.3v v chrg = 5v temperature (c) ?50 0 i trkl (ma) 3 6 9 12 15 ?25 0 25 50 4054l g14 75 100 r prog = 1k r prog = 15k v cc = 5v v bat = 2.5v v cc (v) 4 0 i trkl (ma) 3 6 9 12 15 4.5 5 5.5 6 4054l g15 6.5 7 r prog = 1k r prog = 15k v bat = 2.5v t a = 25c temperature (c) ?50 v trkl (v) 25 75 4054l g16 ?25 0 50 2.950 2.925 2.900 2.875 2.850 2.825 2.800 2.975 3.000 100 v cc = 5v r prog = 1k v bat (v) 2.7 0 i bat (ma) 40 80 120 160 3.0 3.3 3.6 3.9 4054l g17 4.2 4.5 v cc = 5v r prog = 1k t a = 25c ja = 125c/w v cc (v) 4 0 i bat (ma) 40 80 120 160 200 4.5 5 5.5 6 4054l g18 6.5 7 r prog = 1k r prog = 15k v bat = 4v t a = 25c ja = 125c/w temperature (c) ?50 i bat (ma) 120 150 180 25 75 4054l g19 90 60 ?25 0 50 100 125 30 0 r prog = 1k r prog = 15k v bat = 4v v cc = 5v ja = 125c/w onset of thermal regulation temperature (c) ?50 3.99 v rechrg (v) 4.01 4.03 4.05 4.07 4.11 ?25 0 25 50 4054l g20 75 100 4.09 v cc = 5v r prog = 1k temperature (c) ?50 ?25 0.8 r ds(on) (m) 1.2 1.8 0 50 75 4054l g21 1.0 1.6 1.4 25 100 125 v cc = 4.1v v bat = 4v r prog = 1k
ltc4054l-4.2 6 4054l42fa p in func t ions chrg (pin 1): open-drain charge status output. when the battery is charging, the chrg pin is pulled low by an internal n-channel mosfet. when the charge cycle is completed, a weak pull-down of approximately 20a is connected to the chrg pin, indicating an ac present condition. when the ltc4054l detects an undervoltage lockout condition, chrg is forced high impedance. gnd (pin 2): ground. bat (pin 3): charge current output. provides charge cur - rent to the battery and regulates the final float voltage to 4.2v. an internal precision resistor divider from this pin sets this float voltage and is disconnected in shutdown mode. v cc (pin 4): positive input supply voltage. provides power to the charger. v cc can range from 4.25v to 6.5v and should be bypassed with at least a 1f capacitor. when v cc drops to within 30mv of the bat pin voltage, the ltc4054l enters shutdown mode, dropping i bat to less than 2a. prog (pin 5): charge current program, charge current monitor and shutdown pin. the charge current is pro- grammed by connecting a 1% resistor, r prog , to ground. 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 ) ? 150 the prog pin is also used to shut down the charger. disconnecting the program resistor from ground allows a 3a current to pull the prog pin high. when it reaches the 1.21v shutdown threshold voltage, the charger enters shutdown mode, charging stops and the input supply current drops to 25a. this pin is also clamped to ap- proximately 2.4v. driving this pin to voltages beyond the clamp voltage will draw currents as high as 1.5ma. reconnecting r prog to ground will return the charger to normal operation.
ltc4054l-4.2 7 4054l42fa b lock diagra m ? + ? + ? + ? + 3 4 ? + 120c t die t a ma ca c1 c2 1 150 5a va r1 bat r2 r3 1v 0.1v r4 r5 prog 3a v cc r prog ref 1.21v shdn v cc standby chrg 1 5 gnd 4054l42 bd 2 ? + c3 2.9v to bat
ltc4054l-4.2 8 4054l42fa the ltc4054l is a single cell lithium-ion battery charger using a constant-current/constant-voltage algorithm. its ability to control charge currents as low as 10ma make it well-suited for charging low capacity lithium-ion coin cell batteries. the ltc4054l includes an internal p-channel power mosfet and thermal regulation circuitry. no block - ing diode or external sense resistor is required; thus, the basic charger circuit requires only three external compo - nents. furthermore, the ltc4054l is capable of operating from a usb power source. normal charge cycle the charge cycle begins when the voltage at the v cc pin rises above the uvlo level and a 1% program resistor is connected from the prog pin to ground. if the bat pin is less than 2.9v, the charger enters trickle charge mode. in this mode, the ltc4054l supplies approximately 1/10 the programmed charge current in order to bring the battery voltage up to a safe level for full current charging. when 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 final float voltage (4.2v), the ltc4054l enters constant-voltage mode and the charge current begins to decrease. when the charge current drops to 1/10 of the programmed value, the charge cycle ends. programming charge current the charge current is programmed using a single resistor from the prog pin to ground. the battery charge current is 150 times the current out of the prog pin. the program resistor and the charge current are calculated using the following equations: r prog = 150v i chg , i chg = 150v r prog o pera t ion the charge current out of the bat pin can be determined at any time by monitoring the prog pin voltage using the following equation: i bat = v prog r prog ? 150 charge termination the charge cycle is terminated when the charge current falls to 1/10th the programmed value after the final float voltage is reached. this condition is detected by using an internal, filtered comparator to monitor the prog pin. when the prog pin voltage falls below 100mv 1 for longer than t term (typically 1ms), charging is terminated. the charge current is latched off and the ltc4054l enters standby mode, where the input supply current drops to 200a. (note: c/10 termination is disabled in trickle charging and thermal limiting modes.) while charging, transient loads on the bat pin can cause the prog pin to fall below 100mv for short periods of time before the dc charge current has dropped to 1/10th the programmed value. the 1ms filter time (t term ) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. once the average charge current drops below 1/10th the programmed value for longer than t term , the ltc4054l terminates the charge cycle and ceases to provide any current through the bat pin. in this state, all loads on the bat pin must be supplied by the battery. the ltc4054l constantly monitors the bat pin voltage in standby mode. if this voltage drops below the 4.05v recharge threshold (v rechrg ), another charge cycle be - gins and current is once again supplied to the battery. to manually restart a charge cycle when in standby mode, the input voltage must be removed and reapplied, or the charger must be shut down and restarted using the prog pin. figure 1 shows the state diagram of a typical charge cycle. 1 any external sources that hold the prog pin above 100mv will prevent the ltc4054l from terminating a charge cycle.
ltc4054l-4.2 9 4054l42fa o pera t ion charge status indicator (chrg) the charge status output has three different states: strong pull-down (~10ma), weak pull-down (~20a), and high impedance. the strong pull-down state indicates that the ltc4054l is in a charge cycle. once the charge cycle has terminated, the pin state is determined by undervoltage lockout conditions. a weak pull-down indicates that v cc meets the uvlo conditions and the ltc4054l is ready to charge. high impedance indicates that ltc4054l is in undervoltage lock-out mode: either v cc is within 100mv of the bat pin voltage or insufficient voltage is applied to the v cc pin. a microprocessor can be used to distinguish between these three statesthis method is discussed in the applications information section. thermal limiting an internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 120c. this feature protects the ltc4054l 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 ltc4054l. the charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. thinsot power considerations are discussed further in the applications information section. 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. 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 within 30mv of the battery voltage. if the uvlo comparator is tripped, the charger will not come out of shutdown mode until v cc rises 100mv above the battery voltage. trickle charge mode 1/10th full current bat > 2.9v bat < 2.9v bat > 2.9v chrg: strong pull-down charge mode full current chrg: strong pull-down shutdown mode chrg: hi-z in uvlo weak pull-down otherwise prog reconnected or uvlo condition stops prog floated or uvlo condition i cc drops to <25a power on prog < 100mv standby mode no charge current chrg: weak pull-down 2.9v < bat < 4.05v 4054l42 f01 figure 1. state diagram of a typical charge cycle
ltc4054l-4.2 10 4054l42fa o pera t ion manual shutdown at any point in the charge cycle, the ltc4054l can be put into shutdown mode by removing r prog thus floating the prog pin. this reduces the battery drain current to less than 2a and the supply current to less than 50a. a new charge cycle can be initiated by reconnecting the program resistor. in manual shutdown, the chrg pin is in a weak pull-down state as long as v cc is high enough to exceed the uvlo conditions. the chrg pin is in a high impedance state if the ltc4054l is in undervoltage lockout mode: either v cc is within 100mv of the bat pin voltage or insufficient voltage is applied to the v cc pin. automatic recharge once the charge cycle is terminated, the ltc4054l con - tinuously monitors the voltage on the bat pin using a comparator with a 2ms filter time (t recharge ). a charge cycle restarts when the battery voltage falls below 4.05v (which corresponds to approximately 80% to 90% bat- tery capacity). this ensures that the battery is kept at or near a fully charged condition and eliminates the need for periodic charge cycle initiations. chrg output enters a strong pull-down state during recharge cycles.
ltc4054l-4.2 11 4054l42fa a pplica t ions i n f or m a t ion prog 10k r prog c filter 4054l42 f02 charge current monitor circuitry ltc4054l gnd figure 2. isolating capacitive load on prog pin and filtering stability considerations the constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. with no battery present, an output capacitor is recommended to reduce ripple voltage. when using high value, low esr ceramic capacitors, it is recommended to add a 1 resistor in series with the capacitor. no series resistor is needed if tantalum capacitors are used. in constant-current mode, the prog pin is in the feedback loop, not the battery. the constant-current mode stabil - ity 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 20k. however, additional capacitance on this node reduces the maximum allowed program resistor. 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 can be used to calculate the maximum resistance value for r prog : r prog 1 2 ? 10 5 ? c prog average, rather than instantaneous, charge 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 2. a 10k resistor has been added between the prog pin and the filter capacitor to ensure stability. power dissipation the conditions that cause the ltc4054l to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the ic. nearly all of this power dissipation is generated from the internal mosfetthis is calculated to be approximately: p d = (v cc C v bat t* 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. the approximate ambient temperature at which the thermal feedback begins to protect the ic is: t a = 120c C p d ja t a = 120c C (v cc C v bat t* bat t ja example: an ltc4054l operating from a 6v wall adapter is programmed to supply 150ma full-scale current to a discharged li-ion battery with a voltage of 3.75v. assum - ing ja is 200c/w, the ambient temperature at which the ltc4054l will begin to reduce the charge current is approximately: t a o7o7tn"t8 t a o8t8o t a = 52.5c the ltc4054l can be used above 52.5c, but the charge current will be reduced from 150ma. the approximate current at a given ambient temperature can be approxi- mated by: i bat = 120 c ? t a v cc ? v bat ( ) ? ja using the previous example with an ambient temperature of 60c, the charge current will be reduced to approxi- mately: i bat = 120 c ? 60 c 6v ? 3.75v ( ) ? 200 c/w = 60 c 450 c/a i bat = 133ma
ltc4054l-4.2 12 4054l42fa moreover, when thermal feedback reduces the charge current, the voltage at the prog pin is also reduced pro- portionally as discussed in the operation section. it is important to remember that ltc4054l 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 approximately 120c. thermal considerations because of the small size of the thinsot package, it is very important to use a good thermal pc board layout to maximize the available charge current. the thermal path for the heat generated by the ic is from the die to the cop- per lead frame, through the package leads, (especially the ground lead) to the pc board copper. the pc board copper is the heat sink. the footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. feedthrough vias to inner or backside copper layers are also useful in improving the overall thermal performance of the charger. other heat sources on the board, not related to the charger, must also be considered when designing a pc board layout because they will affect overall temperature rise and the maximum charge current. the following table lists thermal resistance for several different board sizes and copper areas. all measurements were taken in still air on 3/32" fr-4 board with the device mounted on topside. table 1. measured thermal resistance (2-layer board*) copper area board area thermal resistance junction-to-ambient topside backside 2500mm 2 2500mm 2 2500mm 2 125c/w 1000mm 2 2500mm 2 2500mm 2 125c/w 225mm 2 2500mm 2 2500mm 2 130c/w 100mm 2 2500mm 2 2500mm 2 135c/w 50mm 2 2500mm 2 2500mm 2 150c/w *each layer uses one ounce copper a pplica t ions i n f or m a t ion table 2. measured thermal resistance (4-layer board**) copper area (each side) board area thermal resistance junction-to-ambient 2500mm 2*** 2500mm 2 80c/w **top and bottom layers use two ounce copper, inner layers use one ounce copper. ***10,000mm 2 total copper area 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, refer to application note 88. charge current soft-start the ltc4054l 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. this has the effect of minimizing the transient current load on the power supply during start-up. chrg status output pin the chrg pin can provide an indication that the input voltage is greater than the undervoltage lockout threshold level. a weak pull-down current of approximately 20a indicates that sufficient voltage is applied to v cc to begin charging. when a discharged battery is connected to the charger, the constant current portion of the charge cycle begins and the chrg pin pulls to ground. the chrg pin can sink up to 10ma to drive an led that indicates that a charge cycle is in progress.
ltc4054l-4.2 13 4054l42fa when the battery is nearing full charge, the charger enters the constant-voltage portion of the charge cycle and the charge current begins to drop. when the charge current drops below 1/10 of the programmed current, the charge cycle ends, and the strong pull-down is replaced by the 20a pull-down, indicating that the charge cycle has ended. if the input voltage is removed or drops below the undervoltage lockout threshold, the chrg pin becomes high impedance. figure 3 shows that by using two differ - ent value pull-up resistors, a microprocessor can detect all three states from this pin. to detect when the ltc4054l is in charge mode, force the digital output pin (out) high and measure the voltage at the chrg pin. the n-channel mosfet will pull the pin voltage low even with the 2k pull-up resistor. once the charge cycle terminates, the n-channel mosfet is turned off and a 20a current source is connected to the chrg pin. the in pin will then be pulled high by the 2k pull-up resistor. to determine if there is a weak pull-down current, the out pin should be forced to a high impedance state. the weak current source will pull the in pin low through the 800k resistor; if chrg is high impedance, the in pin will be pulled high, indicating that the part is in a uvlo state. reverse polarity input voltage protection in some applications, protection from reverse polarity volt- age on v cc is desired. if the supply voltage is high enough, a series blocking diode can be used. in other cases, where the voltage drop must be kept low a p - channel mosfet can be used (as shown in figure 4). usb and wall adapter power the ltc4054l allows charging from both a wall adapter and a usb port. figure 5 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 a schottky diode, d1, is used to prevent usb power loss through the 1k pull-down resistor. figure 3. using a microprocessor to determine chrg state chrg out in 2k 800k 4054l42 f03 ltc4054l processor v + v dd v cc figure 4. low loss input reverse polarity protection figure 5. combining wall adapter and usb power v in v cc ltc4054l drain-bulk diode of fet 4054l42 f04 + ltc4054l-4.2 prog v cc d1 5v wall adapter usb power 100ma system load li-ion battery mp1 1k 1.5k 4 3 5 4054l42 f05 bat a pplica t ions i n f or m a t ion
ltc4054l-4.2 14 4054l42fa p ackage descrip t ion please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. 1.50 ? 1.75 (note 4) 2.80 bsc 0.30 ? 0.45 typ 5 plcs (note 3) datum ?a? 0.09 ? 0.20 (note 3) s5 tsot-23 0302 rev b pin one 2.90 bsc (note 4) 0.95 bsc 1.90 bsc 0.80 ? 0.90 1.00 max 0.01 ? 0.10 0.20 bsc 0.30 ? 0.50 ref note: 1. dimensions are in millimeters 2. drawing not to scale 3. dimensions are inclusive of plating 4. dimensions are exclusive of mold flash and metal burr 5. mold flash shall not exceed 0.254mm 6. jedec package reference is mo-193 3.85 max 0.62 max 0.95 ref recommended solder pad layout per ipc calculator 1.4 min 2.62 ref 1.22 ref s5 package 5-lead plastic tsot-23 (reference ltc dwg # 05-08-1635)
ltc4054l-4.2 15 4054l42fa 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. r evision h is t ory rev date description page number a 8/11 corrected lead count on last bullet item in features. 1
ltc4054l-4.2 16 4054l42fa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com linear technology corporation 2003 lt 0811 rev a ? printed in usa r ela t e d p ar t s typical a pplica t ion full featured single cell li-ion charger basic li-ion battery charger with reverse polarity input protection usb/wall adapter power li-ion charger v cc 330 1f ltc4054l-4.2 bat 4054l42 ta02 prog 1.5k v in = 5v gnd + 4 3 2 5 chrg shdn 1 100ma charging v cc 1f ltc4054l-4.2 bat 4054l42 ta03 prog 1.5k 5v wall adapter gnd 4 3 2 5 + 100ma + ltc4054l-4.2 prog v cc 5v wall adapter usb power li-ion cell 1k 1.5k 4 3 5 2 4054l42 ta05 gnd 1f bat 100ma part number description comments ltc1731 lithium-ion linear battery charger controller simple charger uses external fet, features preset voltages, c/10 charger detection and programmable timer ltc1732 lithium-ion linear battery charger controller simple charger uses external fet, features preset voltages, c/10 charger detection and programmable timer, input power good indication ltc1733 monolithic lithium-ion linear battery charger standalone charger with programmable timer, up to 1.5a charge current ltc1734 lithium-ion linear battery charger in thinsot simple thinsot charger, no blocking diode, no sense resistor needed ltc1734l lithium-ion linear battery charger in thinsot low current version of ltc1734 ltc1998 lithium-ion low battery detector 1% accurate 2.5a quiescent current, sot-23 ltc4050 lithium-ion linear battery charger controller simple charger uses external fet, 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, safety current limit ltc4053 usb compatible monolithic li-ion battery charger standalone charger with programmable timer, up to 1.25a charge current ltc4054 800ma standalone linear li-ion battery charger with thermal regulation in thinsot no external mosfet, sense resistor or blocking diode required, charge current monitor for gas gauging, c/10 charge termination ltc4056 standalone lithium-ion linear battery charger in thinsot standalone charger with programmable timer, no blocking diode, no sense resistor needed ltc4057 monolithic lithium-ion linear battery charger with thermal regulation in thinsot no external mosfet, sense resistor or blocking diode required, charge current monitor for gas gauging ltc4058 950ma standalone li-ion charger in 3mm w 3mm dfn usb compatible, thermal regulation protects against overheating ltc4410 usb power manager for simultaneous operation of usb peripheral and battery charging from usb port, keeps current drawn from usb port constant, keeps battery fresh, use with the ltc4053, ltc1733, or ltc4054

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