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1 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs standalone linear li-ion battery charger with thermal regulation in dfn programmable charge current up to 950ma complete linear charger in dfn package no mosfet, sense resistor or blocking dioderequired thermal regulation maximizes charge ratewithout risk of overheating* battery kelvin sensing improves charging accuracy charges directly from a usb port c/10 charge termination preset 4.2v charge voltage with 1% accuracy charge current monitor output for gas gauging* automatic recharge charge status output ac present output 2.9v trickle charge threshold (ltc4058) available without trickle charge (ltc4058x) soft-start limits inrush current low profile (3mm 3mm 0.75mm) dfn package cellular telephones, pdas, mp3 players bluetooth applications , ltc and lt are registered trademarks of linear technology corporation. the ltc ? 4058 is a complete constant-current/constant- voltage linear charger for single cell lithium-ion batteries.its dfn package and low external component count make the ltc4058 ideally suited for portable applications. fur- thermore, the ltc4058 is designed to work within usb power specifications. the ltc4058 can kelvin sense the battery terminal for more accurate float voltage charging. no external sense resistor or external blocking diode are required due to the internal mosfet architecture. thermal feedback regu- lates the charge current to limit the die temperature during high power operation or high ambient temperature condi- tions. the charge voltage is fixed at 4.2v and the charge current is programmed with a resistor. the ltc4058 terminates the charge cycle when the charge current drops to 10% of the programmed value after the final float voltage is reached. when the input supply (wall adapter or usb supply) is removed, the ltc4058 enters a low current state dropping the battery drain current to less than 2 m a. other features include charge current monitor, undervoltage lockout,automatic recharge and status pins to indicate charge termination and the presence of an input voltage. bat v cc bsense chrg 1.65k 405842 ta01 1 f v in 4.5v to 6.5v 1-cellli-ion battery ltc4058-4.2 600ma acpr en prog gnd + time (hours) 0 charge current (ma) 1.5 405842 ta02 0.5 1.0 2.25 700600 500 400 300 200 100 0 4.754.50 4.25 4.00 3.75 3.50 3.25 3.00 0.25 0.75 1.25 2.0 1.75 constant voltage constant current battery voltage (v) v cc = 5v q ja = 40 c/w r prog = 1.65k t a = 25 c complete charge cycle (750mah battery) *us patent 6,522,118 single cell li-ion battery charger with kelvin sense descriptio u features applicatio s u typical applicatio u downloaded from: http:///
2 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs (note 1)input supply voltage (v cc ) ....................... C0.3v to 10v prog ............................................. C 0.3v to v cc + 0.3v bat, bsense .............................................. C0.3v to 7v chrg, acpr, en ...................................... C0.3v to 10v bat short-circuit duration .......................... continuous bat pin current ........................................................ 1a prog pin current ................................................... 1ma maximum junction temperature .......................... 125 c operating temperature range (note 2) .. C 40 c to 85 c storage temperature range ................. C 65 c to 125 c t jmax = 125 c, q ja = 40 c/w (note 3) exposed pad is ground (pin 9) must be soldered to pcb order part number dd part marking laevlbdh symbol parameter conditions min typ max units v cc input supply voltage 4.25 6.5 v i cc input supply current charge mode (note 4), r prog = 10k 0.3 1 ma standby mode (charge terminated) 200 500 m a shutdown mode (en = 5v, v cc < v bsense 25 50 m a or v cc < v uv ) v float regulated output (float) voltage 0 c t a 85 c, 4.3v < v cc < 6.5v 4.158 4.2 4.242 v i bat bat pin current r prog = 10k, current mode 93 100 107 ma r prog = 2k, current mode 465 500 535 ma i bsense bsense pin current (note 5) standby mode, v bsense = 4.2v C2.5 C6 m a shutdown mode (en = 5v, v cc < v bsense or 1 2 m a v cc < v uv ) sleep mode, v cc = 0v 1 2 m a i trikl trickle charge current v bsense < v trikl , r prog = 2k (note 6) 30 45 60 ma v trikl trickle charge threshold voltage r prog = 10k, v bsense rising (note 6) 2.8 2.9 3 v v trhys trickle charge hysteresis voltage r prog = 10k (note 6) 60 80 110 mv v uv v cc undervoltage lockout voltage from v cc low to high 3.7 3.8 3.92 v v uvhys v cc undervoltage lockout hysteresis 150 200 300 mv v en(il) en pin input low voltage 0.4 0.7 v v en(ih) en pin input high voltage 0.7 1 v r en en pin pull-down resistor 1.2 2 5 m w v asd v cc C v bsense lockout threshold v cc from low to high 70 100 140 mv v cc from high to low 5 30 50 mv i term c/10 termination current threshold r prog = 10k (i chg = 100ma) (note 7) 0.085 0.10 0.115 ma/ma r prog = 2k (i chg = 500ma) 0.085 0.10 0.115 ma/ma v prog prog pin voltage r prog = 10k, current mode 0.93 1 1.07 v v chrg chrg pin output low voltage i chrg = 5ma 0.35 0.6 v v acpr acpr pin output low voltage i acpr = 5ma 0.35 0.6 v d v rechrg recharge battery threshold voltage v float C v rechrg , 0 c t a 85 c 60 100 140 mv the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v cc = 5v, unless otherwise noted. absolute axi u rati gs w ww u package/order i for atio uu w electrical characteristics consult ltc marketing for parts specified with wider operating temperature ranges. ltc4058edd-4.2ltc4058xedd-4.2 top view 9 dd package 8-lead (3mm 3mm) plastic dfn 5 6 7 8 4 3 2 1 bsense bat chrg gnd enacpr v cc prog downloaded from: http:///
3 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired.note 2: the ltc4058e-4.2/ltc4058xe-4.2 are guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C40 c to 85 c 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 will result in a thermal resistance much higher than 40 c/w. symbol parameter conditions min typ max units t lim junction temperature in constant 120 c temperature mode r on power fet on resistance 600 m w (between v cc and bat) t ss soft-start time i bat = 0 to i bat =1000v/r prog 100 m s t recharge recharge comparator filter time v bsense 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 m s the denotes specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v cc = 5v, unless otherwise noted. electrical characteristics note 4: supply current includes prog pin current (approximately 100 m a) but does not include any current delivered to the battery through the batpin (approximately 100ma). note 5: for all li-ion applications, the bsense pin must be electrically connected to the bat pin.note 6: this parameter is not applicable to the ltc4058x. note 7: i term is expressed as a fraction of measured full charge current with indicated prog resistor. typical perfor a ce characteristics uw prog pin voltage vs supplyvoltage (constant current mode) v cc (v) 4 0.985 v prog (v) 0.990 0.995 1.000 1.005 1.015 4.5 5 5.5 6 405842 g01 6.5 7 1.010 v cc = 5v v bat = v bsense = 4v t a = 25 c r prog = 10k temperature ( c) C50 v prog (v) 0.9975 1.0000 1.0025 25 75 405842 g02 0.9950 0.9925 0.9900 C25 0 50 1.0050 1.0075 1.0100 100 v cc = 5v v bat = v bsense = 4v r prog = 10k v prog (v) 0 0 i bat (ma) 100 200 300 400 600 0.2 0.4 0.6 0.8 405842 g03 1 1.2 500 v cc = 5v t a = 25 c r prog = 2k prog pin voltagevs temperature charge currentvs prog pin voltage downloaded from: http:///
4 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs typical perfor a ce characteristics uw regulated output (float) voltagevs charge current i bat (ma) 0 v float (v) 4.24 300 405842 g04 4.18 4.14 100 200 400 4.124.10 4.264.22 4.20 4.16 500 600 700 v cc = 5v t a = 25 c r prog = 1.25k regulated output (float) voltagevs temperature temperature ( c) C50 4.185 v float (v) 4.190 4.195 4.200 4.205 4.215 C25 02 55 0 405842 g05 75 100 4.210 v cc = 5v r prog = 10k regulated output (float) voltagevs supply voltage 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 405842 g06 6.5 7 4.210 t a = 25 c r prog = 10k chrg pin i-v curve(pull-down state) trickle charge currentvs temperature acpr pin i-v curve(pull-down state) v chrg (v) 0 i chrg (ma) 20 25 30 35 405842 g07 15 10 12 46 7 5 0 t a = C40 c t a = 25 c t a = 90 c v cc = 5v v bat = v bsense = 4v v acpr (v) 0 i acpr (ma) 20 25 30 35 405842 g08 15 10 12 46 7 5 0 t a = C40 c t a = 25 c t a = 90 c v cc = 5v v bat = v bsense = 4v temperature ( c) C50 0 i trkl (ma) 10 20 30 40 60 C25 02 55 0 405842 g09 75 100 50 v cc = 5v v bat = v bsense = 2.5v r prog = 2k r prog = 10k trickle charge currentvs supply voltage charge current vs battery voltage v cc (v) 4 0 i trkl (ma) 10 20 30 40 60 4.5 5 5.5 6 405842 g10 6.5 7 50 v bat = v bsense = 2.5v t a = 25 c r prog = 2k r prog = 10k trickle charge threshold voltagevs temperature temperature ( c) C50 v trkl (v) 2.875 2.900 2.925 25 75 405842 g11 2.850 2.825 2.800 C25 0 50 2.950 2.975 3.000 100 v cc = 5v r prog = 10k v bat (v) 2.4 i bat (ma) 400 500 600 3.3 3.9 405842 g08 300 200 2.7 3 3.6 4.2 4.5 100 0 v cc = 5v q ja = 40 c/w r prog = 2k downloaded from: http:///
5 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs typical perfor a ce characteristics uw charge current vs supply voltage charge currentvs ambient temperature recharge threshold voltagevs temperature power fet transistor curve power fet ?n?resistancevs temperature v cc (v) 4 0 i bat (ma) 100 200 300 400 600 4.5 5 5.5 6 405842 g13 6.5 7 500 v bat = v bsense = 4v t a = 25 c q ja = 40 c/w r prog = 2k r prog = 10k temperature ( c) C50 i bat (ma) 400 500 600 25 75 405842 g14 300 200 C25 0 50 100 125 100 0 v cc = 5v v bat = v bsense = 4v q ja = 40 c/w r prog = 2k onset of thermal regulation r prog = 10k temperature ( c) C50 4.04 v rechrg (v) 4.06 4.08 4.10 4.12 4.16 C25 02 55 0 405842 g15 75 100 4.14 v cc = 5v r prog = 10k v bat (v) 3.8 i bat (ma) 300 400 500 4.7 5.3 405842 g16 200 100 0 4.1 4.4 5 600 700 800 v cc = 5v v bsense = 3.5v t a = 25 c r prog = 2k temperature ( c) C50 300 r ds(on) (m ) 400 500 600 700 800 C25 02 55 0 405842 g17 75 100 v cc = 5v v bat = 4.8v v bsense = 4v r prog = 2k uu u pi fu ctio s bsense (pin 1): battery sense. this pin is used to kelvin sense the positive battery terminal and regulate the finalfloat voltage to 4.2v. an internal precision resistor divider sets this float voltage and is disconnected in shutdown mode. for li-ion applications, this pin must be electri- cally connected to bat . bat (pin 2): charge current output. provides charge current to the battery from the internal p-channel mosfet.chrg (pin 3): charge status open-drain output. when the battery is charging, the chrg pin is pulled low by an internal n-channel mosfet. when the charge cycle iscompleted, chrg becomes high impedance. gnd (pins 4, 9): ground/exposed pad. the exposed backside of the package (pin 9) is also ground and mustbe soldered to the pc board for maximum heat transfer. prog (pin 5): charge current program and charge cur- rent monitor. charge current is programmed by connect-ing a 1% resistor, r prog , to ground. when charging in constant-current mode, this pin servos to 1v. in all modes, downloaded from: http:///
6 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs uu u pi fu ctio s the voltage on this pin can be used to measure the chargecurrent using the following formula: i bat = (v prog /r prog ) ? 1000 this pin is clamped to approximately 2.4v. driving this pinto voltages beyond the clamp voltage can draw currents as high as 1.5ma. v cc (pin 6): positive input supply voltage. provides power to the charger. v cc can range from 4.25v to 6.5v. this pin should be bypassed with at least a 1 m f capacitor. when v cc is within 100mv of the bsense pin voltage, the ltc4058 enters shutdown mode dropping the batterydrain current to less than 2 m a. acpr (pin 7): power supply status open-drain output. when v cc is greater than the undervoltage lockout thresh- old and at least 100mv above v bsense , the acpr pin is pulled to ground; otherwise, the pin is high impedance.en (pin 8): enable input . a logic high on the en pin will put the ltc4058 into shutdown mode where the battery draincurrent is reduced to less than 2 m a and the supply current is reduced to less than 50 m a. a logic low or floating the en pin (allowing an internal 2m w pull-down resistor to pull this pin low) enables charging. block diagra w C + C + C + 2 6 C + 120 c t die t a ma ca c1 1 1000 va r1 bat 1 bsense r2 r3 1v0.1v r4 r5 prog trickle chargedisabled on the ltc4058x 5 a r prog r en ref 1.21v v cc chrg 3 en 8 gnd 4, 9 405842 bd C + c2 2.9v to bat term acpr charge shdn en logic acpr 7 5 downloaded from: http:///
7 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs operatio u the ltc4058 is a single cell lithium-ion battery chargerusing a constant-current/constant-voltage algorithm. it can deliver up to 950ma of charge current (using a good thermal pcb layout) with a final float voltage accuracy of 1%. the ltc4058 includes an internal p-channel power mosfet and thermal regulation circuitry. no blockingdiode or external current sense resistor is required; thus, the basic charger circuit requires only two external com- ponents. furthermore, the ltc4058 is capable of operat- ing from a usb power source. normal charge cycle a charge cycle begins when the voltage at the v cc pin rises above the uvlo threshold level and a 1% program resistoris connected from the prog pin to ground. if the bsense pin is less than 2.9v, the charger enters trickle charge mode. in this mode, the ltc4058 supplies approximately 1/10th the programmed charge current to bring the battery volt- age up to a safe level for full current charging. (note: the ltc4058x does not include this trickle charge feature.) when the bsense pin voltage rises above 2.9v, the charger enters constant-current mode where the programmed charge current is supplied to the battery. when the bsense pin approaches the final float voltage (4.2v), the ltc4058 enters constant-voltage mode and the charge current be- gins to decrease. when the charge current drops to 1/10th 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 charge current out of the bat pin is 1000 times the current out of the prog pin. the program resistor and the charge current are calcu- lated using the following equations: r v i i v r prog chg chg prog == 1000 1000 , charge current out of the bat pin can be determined at anytime by monitoring the prog pin voltage and using the following equation: i v r bat prog prog = ? 1000 charge terminationthe charge cycle terminates when the charge current falls to 10% 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 ltc4058 enters standbymode where the input supply current drops to 200 m a. (note: c/10 termination is disabled in trickle charging andthermal limiting modes.) when 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 10% of the programmed value. the 1ms filter time (t term ) on the termination comparator ensures that transient loads ofthis nature do not result in premature charge cycle termi- nation. once the average charge current drops below 10% of the programmed value, the ltc4058 terminates thecharge 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 ltc4058 constantly monitors the bat pin voltage in standby mode. if this voltage drops below the 4.1v recharge threshold (v rechrg ), another charge cycle begins and charge current is once again supplied to the battery. tomanually 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 en pin. figure? 1 shows the state diagram of a typical charge cycle. charge status indicator (chrg) the charge status output has two states: pull-down and high impedance. the pull-down state indicates that the ltc4058 is in a charge cycle. once the charge cycle has terminated or the ltc4058 is disabled, the pin state becomes high impedance. 1 any external sources that hold the prog pin above 100mv will prevent the ltc4058 from terminating a charge cycle. downloaded from: http:///
8 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs operatio u power supply status indicator (acpr)the power supply status output has two states: pull-down and high impedance. the pull-down state indicates that v cc is above the uvlo threshold (3.8v) and is also 100mv above the battery voltage. when these conditions are notmet, the acpr pin is high impedance indicating that the ltc4058 is unable to charge the battery. 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 120 c. this feature protects the ltc4058 from excessive temperature and allows theuser to push the limits of the power handling capability of a given circuit board without risk of damaging the ltc4058. 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-caseconditions. dfn power considerations are discussed fur- ther 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 uvlocircuit 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 bsense voltage. if the uvlocomparator is tripped, the charger will not come out of shutdown mode until v cc rises 100mv above the bsense voltage.manual shutdown at any point in the charge cycle, the ltc4058 can be put into shutdown mode by driving the en pin high. this reduces the battery drain current to less than 2 m a and the supply current to less than 50 m a. when in shutdown mode, the chrg pin is in the high impedance state. a newcharge cycle can be initiated by driving the en pin low. a resistor pull-down on this pin forces the ltc4058 to be enabled if the pin is allowed to float. automatic recharge once the charge cycle is terminated, the ltc4058 continu- ously monitors the voltage on the bsense pin using a comparator with a 2ms filter time (t recharge ). a charge cycle restarts when the battery voltage falls below 4.10v(which corresponds to approximately 80% to 90% battery capacity). 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 enters a pull-down state during recharge cycles. figure 1. state diagram of a typical charge cycle trickle charge mode 1/10th full current bsense > 2.9v bsense < 2.9v bsense > 2.9v chrg: strong pull-down charge mode full current chrg: strong pull-down shutdown mode chrg: hi-z en driven low or uvlo condition stops en driven high or uvlo condition i cc drops to <25 a power on prog < 100mv standby mode no charge current chrg: hi-z 2.9v < bsense < 4.1v 405842 f01 downloaded from: http:///
9 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs applicatio s i for atio wu uu kelvin sensing the battery (bsense pin)the internal p-channel mosfet drain is connected to the bat pin, while the bsense pin connects through an inter- nal precision resistor divider to the input of the constant- voltage amplifier. this architecture allows the bsense pin to kelvin sense the positive battery terminal. this is espe- cially useful when the copper trace from the bat pin to the li-ion battery is long and has a high resistance. high charge currents can cause a significant voltage drop be- tween the positive battery terminal and the bat pin. in this situation, a separate trace from the bsense pin to the battery terminals will eliminate this voltage error and re- sult in more accurate battery voltage sensing. the bsense pin must be electrically connected to the bat pin . stability considerationsthe constant-voltage mode feedback loop is stable with- out an output capacitor, provided a battery is connected to the charger output. with no battery present, an output capacitor on the bat pin is recommended to reduce ripple voltage. when using high value, low esr ceramic capaci- tors, it is recommended to add a 1 w resistor in series with the capacitor. no series resistor is needed if tantalumcapacitors are used. in constant-current mode, the prog pin is in the feedback loop, not the battery. the constant-current mode 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 20k; how- ever, 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 maximumresistance value for r prog : r c prog prog p 1 210 5 ?? average, rather than instantaneous charge current may beof 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 theinstantaneous 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. ltc4058-4.2 gnd prog r prog 10k c filter 405842 f02 chargecurrent monitor circuitry figure 2. isolating capacitive load on prog pin and filtering power dissipationit is not necessary to design for worst-case power dissi- pation scenarios because the ltc4058 automatically re- duces the charge current during high power conditions. the conditions that cause the ltc4058 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 by the internal mosfetthis is calculated to be approximately: 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. the approximate ambient temperature at whichthe thermal feedback begins to protect the ic is: t a = 120 c C p d q ja t a = 120 c C (v cc C v bat ) ? i bat ? q ja example: an ltc4058 operating from a 5v supply isprogrammed to supply 800ma full-scale current to a discharged li-ion battery with a voltage of 3.3v. assuming q ja is 50 c/w (see thermal considerations), the ambient temperature at which the ltc4058 will begin to reduce thecharge current is approximately: t a = 120 c C (5v C 3.3v) ? (800ma) ? 50 c/w t a = 120 c C 1.36w ? 50 c/w = 120 c C 68 c t a = 52 c downloaded from: http:///
10 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs the ltc4058 can be used above 52 c ambient but the charge current will be reduced from 800ma. the approxi-mate current at a given ambient temperature can be approximated by: i ct vv bat a cc bat ja = () 120 C C? q using the previous example with an ambient temperatureof 60 c, the charge current will be reduced to approximately: i cc vv c w c ca im a batbat = () = = 120 60 533 5 0 60 85 706 C C. ? / / moreover, when thermal feedback reduces the charge cur-rent the voltage at the prog pin is also reduced proportion- ally as discussed in the operation section. it is important to remember that ltc4058 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 120 c. thermal considerationsi n order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on thebackside of the ltc4058 package is soldered to the pc board ground. correctly soldered to a 2500mm 2 double- sided 1oz copper board, the ltc4058 has a thermalresistance of approximately 40 c/w. failure to make thermal contact between the exposed pad on the back-side of the package and the copper board will result in thermal resistances far greater than 40 c/w. as an example, a correctly soldered ltc4058 can deliver over800ma to a battery from a 5v supply at room tempera- ture. without a backside thermal connection, this num- ber will drop considerably. v cc bypass capacitor many types of capacitors can be used for input bypassing,however, caution must be exercised when using multilayer applicatio s i for atio wu uu ceramic capacitors. because of the self-resonant and highq 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 w resistor in series with an x5r ceramic capacitor will minimize start-upvoltage transients. for more information, see application note 88. charge current soft-start the ltc4058 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 100 m s. this has the effect of minimizing the transient current loadon the power supply during start-up. usb and wall adapter power the ltc4058 allows charging from both a wall adapter and a usb port. 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 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. + ltc4058-4.2 bat bsense prog v cc gnd d1 5v wall adapter 800ma i chg usb power 500ma i chg i chg systemload li-ionbattery mp1 1k 3.3k 2k mn1 6 4, 9 21 5 405842 f03 figure 3. combining wall adapter and usb power downloaded from: http:///
11 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs dd package 8-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1698) u package descriptio 3.00 0.10 (4 sides) note:1. drawing to be made a jedec package outline m0-229 variation of (weed-1) 2. all dimensions are in millimeters 3. 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 4. exposed pad shall be solder plated 0.38 0.10 bottom viewexposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.115 typ 2.38 0.10 (2 sides) 1 4 8 5 pin 1 top mark 0.200 ref 0.00 C 0.05 (dd8) dfn 0203 0.28 0.05 2.38 0.05 (2 sides) recommended solder pad pitch and dimensions 1.65 0.05 (2 sides) 2.15 0.05 0.50bsc 0.675 0.05 3.5 0.05 packageoutline 0.28 0.05 0.50 bsc information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen-tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. applicatio s i for atio wu uu v in v cc ltc4058 drain-bulk diode of fet 405842 f04 figure 4. low loss input reverse polarity protection reverse polarity input voltage protectionin 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 othercases, where the voltage drop must be kept low, a p-channel mosfet can be used (as shown in figure 4). downloaded from: http:///
12 ltc4058-4.2/ltc4058x-4.2 sn405842 405842fs related parts part number description comments 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 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 ltc1998 lithium-ion low battery detector 1% accurate 2.5 m a quiescent current, sot-23 ltc4007 4a multicell li-ion battery charger standalone charger, 6v v in 28v, up to 96% efficiency, 0.8% charging voltage accuracy 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 li-ion linear battery charger up to 800ma charge current, thermal regulation, thinsot package 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, usewith the ltc4053, ltc1733, or ltc4054 ltc4412 low loss powerpath tm controller in thinsot automatic switching between dc sources, load sharing, replaces oring diodes thinsot and powerpath are trademarks of linear technology corporation. typical applicatio s u full featured single cell li-ion charger bat v cc bsense chrg 2k 5 8 3 7 4, 9 1 2 6 405842 ta03 1 f 4.7 f v in 5v 1-cellli-ion battery ltc4058-4.2 500ma acpr en prog gnd 1k 1k + li-ion battery charger with reverse polarity input protection bat v cc bsense 2k 5 8 4, 9 1 2 6 405842 ta04 4.7 f 5v wall adapter ltc4058-4.2 500ma en prog gnd 1-cellli-ion battery + lt/tp 1103 1k ? printed in usa ? linear technology corporation 2003 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com usb/wall adapter power li-ion charger + ltc4058-4.2 prog v cc 5v wall adapter usb power li-ioncell 1k 10k 2.5k 6 21 5 4, 9 405842 ta05 gnd 1 f 100ma/500ma c bat bsense i bat downloaded from: http:///

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