preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 1 of 9 10v/1.2a single-chip li-ion and li-pol charge general description the lp28019 is a complete constant-current/ constant- voltage linear charger for single cell lithium-ion batteries. its tdfn-10 package and low external component count make the lp28019 ideally suited for portable applications. furthermore, the lp28019 is specifically designed to work within usb power specifications. its have a over voltage protection in input with 6.5v and support over zero voltages of battery can charge enable. 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 limit the die temperature during high power operation or high ambient temperature. the charge voltage is fixed at 4.2v, and the charge current can be iset rammed externally with a single resistor. the lp28019 automatically terminates the charge cycle when the charge current drops to 1/10th the iset rammed value after the final float voltage is reached. when the input supply (wall adapter or usb supply) is removed, the lp28019 automatically enters a low current state, dropping the battery drain current to less than 2a. the lp28019 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. order information lp28019 f: pb-free package type sp: esop-8(p) so:sop-8 applications ? portable media players/mp3 players ? cellular and smart mobile phone ? pda/dsc ? bluetooth applications features z very low power dissipation z vin over voltage protection:6.5v z short-circuit protection z programmable charge current up to 1500ma z no mosfet, sense resistor or blocking diode required z constant-current/constant- voltage operation with thermal regulation to maximize charge rate without risk of overheating z charges single cell li-ion batteries directly from usb port z 25a supply current in shutdown z time pre-charge conditioning with safety timer reverse leakage protection prevents battery z drainage charge current thermal regulation status outputs for led or system interface z indicates charge and fault conditions z optional battery temperature monitoring before and during charge automatic sleep mode for low-power z consumption available in sop-8p package z rohs compliant and 100% lead (pb)-free typical application circuit batter y red 10uf vin 10uf chrg_s 2 gnd 4 iseta 5 acin 1 batt 8 nc 7 gnd 9 lp28019spf i set =1000/rset marking information please see website.
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 2 of 9 functional pin description package type pin configurations sop-8(p) 5 1 8 7 6 4 3 2 gnd nc chg_s acin pgnd batt nc nc iseta lp28019 9 pin description pin pin number description vin 1 vin is the input power sour ce. connect to a wall adapter. stat 2 open-drain charge status output. when the batter y is charging, the stat pin is pulled low by an internal n-channel mosfet. when the charge cycle is completed, the pin is pulled high. nc 3,6,7 no connector. vss/pgnd 4,9 vss is the connection to system ground. iset 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 ) ? 1000 batt 8 vbat is the connection to the battery. typically a 1f tantalum capacitor is needed for stability when there is no battery attached. when a battery is attached, only a 0.1f ceramic capacitor is required.
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 3 of 9 function block diagram absolute maximum ratings ? input voltage to gnd (vin) ----------------------------------------------------------------------------- 2.6v to 10v ? bat, iset, stat (vx) ---------------------------------------------------------------------- 0.3v to vin+0.3v ? bat short-circuit duration ---------------------------------------------------------------------------- continuous ? bat pin current ------------------------------------------------------------------------------------------ 1500ma ? maximum junction temperature ---------------------------------------------------------------------------- 125c ? operating junction temperature range (tj) ----------------------------------------------------- -40 to 85 c ? maximum soldering temperature (at leads, 10 sec) ------------------------------------------------------ 260 c thermal information ? maximum power dissipation (pd,ta<40 c ) -------------------------------------------------------------- 1.5w ? thermal resistance (ja) --------------------------------------------------------------------------------- 46 /w iset stat vin vss lp28019
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 4 of 9 electrical characteristics (the specifications which apply over the full operating temperature range, otherwise specifications are at ta = 25c. vcc = 5v, unless otherwise noted.) symbol parameter conditions min typ. max units v in adapter/usb voltage range 2.65 5 7 v i cc input supply current charge mode (note 4), r iset = 10k standb y mode ( char g e terminated ) 300 2000 ua shutdown mode (r iset not connected, 200 500 v cc < v bat , or v cc < v uv ) 25 50 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 iset = 1k, current mode 1000 ma r iset = 2k, current mode 50 standby mode, v bat = 4.2v shutdown mode (r iset not connected) sleep mode, v cc = 0v 0 -2.5 1 1 -6 2 2 ua i trikl trickle charge current v bat < v trikl , r iset = 2k (note 5) 50 ma v trikl trickle charge threshold voltage r iset = 10k, v bat rising (note 5) 2.8 2.9 3.0 v v trhys trickle charge hysteresis voltage r iset = 10k (note 5) 60 80 110 mv v uv v cc undervoltage lockout threshold from v cc low to high 3.7 3.8 3.95 v v uvhys v cc undervoltage lockout hysteresis 150 200 300 mv v msd manual shutdown threshold voltage iset pin rising 1.15 1.21 1.30 v iset pin falling 0.9 1.0 1.1 v v asd v cc ? v bat lockout threshold voltage 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 iset = 10k (note 6) 0.085 0.10 0.115 ma/ma r iset = 2k 0.085 0.10 0.115 ma/ma v iset iset pin voltage r iset = 10k, current mode 0.9 1.0 1.1 v i stat stat pin weak pull-down current v stat = 5v 8 20 35 ua v stat stat pin output low voltage i stat = 5ma 0.35 0.6 v v restat recharge battery threshold voltage v float - v restat 100 150 200 mv t lim junction temperature in co nstant temperature mode 120 c r on power fet ?on? resistance (between v cc and bat) 600 m ? t ss soft-start time i bat = 0 to i bat =850v/r iset 100 us i iset iset pin pull-up current 3 ua vin ovp over voltage protection 5.9 6.2 6.5 v
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 5 of 9
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 6 of 9 typical operating characteristics
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 7 of 9 operation the lp28019 is a single cell lithium-ion battery charger using a constant-current/constant -voltage algorithm. it can deliver up to 1200ma of charge current (using a good thermal pcb layout) with a final float voltage accuracy of 1%. the lp28019 includes an internal p-channel power mosfet and thermal regulation circuitry. no blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components. furthermore, the lp28019 is capable of operating 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% iset ram resistor is connected from the iset pin to ground or when a battery is connected to the charger output. if the bat pin is less than 2.9v, the charger enters trickle charge mode. in this mode, the lp28019 supplies approximately 1/10 the iset rammed charge current to bring the battery voltage up to a safe level for full current charging. (note: the lp28019x does not include this trickle charge feature). when the bat pin voltage rises above 2.9v, the charger enters constant-current mode, where the iset rammed charge current is supplied to the battery. when the bat pin approaches the final float voltage (4.2v), the lp28019 enters constant-voltage mode and the charge current begins to decrease. when the charge current drops to 1/10 of the iset rammed value, the charge cycle ends. iset ramming charge current the charge current is iset rammed using a single resistor from the iset pin to ground. the battery charge current is 1000 times the current out of the iset pin. the iset ram resistor and the charge current are calculated using the following equations: r set =1000v/i chg i chg = 1000v/r set the charge current out of the bat pin can be determined at any time by monitoring the iset pin voltage using the following equation: i bat = v set x 1000/r set charge termination a charge cycle is terminated when the charge current falls to 1/10th the iset rammed value after the final float voltage is reached. this condition is detected by using an internal, filtered comparator to monitor the iset pin. when the iset pin voltage falls below 100mv 1 for longer than t term (typically 1ms), charging is terminated. the charge current is latched off and the lp28019 enters standby mode, where the input supply current drops to 200a. (note: c/10 termination is disabled in trickle charging and thermal limiting modes). when charging, transient loads on the bat pin can cause the iset pin to fall below 100mv for short periods of time before the dc charge current has dropped to 1/10th the iset rammed 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 iset rammed value, the lp28019 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 lp28019 constantly monitors the bat pin voltage in standby mode. if this voltage drops below the 4.05v recharge threshold (v restat ), another charge cycle begins 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 iset pin. figure 1 shows the state diagram of a typical charge cycle. charge status indicator (stat) 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 lp28019 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 an d the lp28019 is ready to charge. high impedance indicates that the lp28019 is in undervoltage lockout mode: either v cc is less than 100mv above the bat pin voltage or insufficient voltage is applied to the v cc pin. a microprocessor can be used to distinguish between these three states?this method is discussed in the applications information section. thermal limiting an internal thermal feedback loop reduces the iset rammed charge current if the die temperature attempts to rise above a preset value of approximately 120c. this feature protects the lp28019 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 lp28019. the charge current can be set according to typical (not worst-case) ambient temperature with the
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 8 of 9 assurance that the charger will automatically reduce the current in worst-case conditions. tdfn power consid- erations are discussed further in the applications informa- tion 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. manual shutdown at any point in the charge cycle, the lp28019 can be put into shutdown mode by removing r iset thus floating the iset 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 isetram resistor. in manual shutdown, the stat pin is in a weak pull-down state as long as v cc is high enough to exceed the uvlo conditions. the stat pin is in a high impedance state if the lp28019 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 lp28019 continu- ously monitors the voltage on the bat pin using a com- parator 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% 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. stat output enters a strong pull-down state during recharge cycles. power dissipation the conditions that cause the lp28019 battery charger to reduce charge current through thermal feedback can be approximated by considering the total power dissipated in the ic. for high charge currents, the lp28019 power dissipation is approximately: where pd is the total power dissipated within the ic, adp is the input supply voltage, vbat is the battery voltage, ibat is the charge current and pd_buck is the power dissipation due to the regulator. pd_buck can be calculated as: where voutb is the regulated output of the switching regulator, ioutb is the regulator load and is the regulator efficiency at that particular load. it is not necessary to perform worst-case power dissipation scenarios be cause the lp28019 will automatically reduce the charge current to maintain the die temperature at approximately 125c. however, the approximate ambient temperature at which the thermal feedback begins to rotect the ic is: example: consider the extreme case when an lp28019 is operating from a 6v supply providing 250ma to a 3v li-ion battery, the switching regulator and the ldo are off. the ambient temperature above which the lp28019 will begin to reduce the 250ma charge current is approximately: (correctly soldered to a 2500mm 2 double-sided 1 oz. copper board, the lp28019 has a thermal resistance of approximately 43c/w.) t= if there is more power dissipation due to the switching regulator or the ldo, the thermal regulation will kick in at a somewhat lower temperature than this. in the above circumstances, the lp28019 can be used above 82.75c, but the charge current will be reduced from 250ma. the approximate current at a given ambient temperature can be calculated: o o o note: 1v = 1j/c = 1w/a furthermore, the voltage at the iset pin will change proportionally with the charge current as discussed in the iset ramming charge current section.
preliminary datasheet lp28019 lp28019 C 000 version 1.0 datasheet feb.-2012 www.lowpowersemi.com page 9 of 9 packaging information
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