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LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 description the LX2208 is a single cell lithium ion or lithium polymer battery charger. the controller will charge a single cell li-ion battery from either a wall adapter or a usb power source. a low under-voltage lockout level increases usable charging range from a current limited power source. in addition, there is a linear die temperatur e thermal control loop, which limits the heat dissipation while still charging the battery. there are three logic selectable and programmable charge current levels: the high charge programming level is typically set for charging from the wall adapter, the low level charge programming is typically set to 500ma for full usb charging and 100ma (20%) for reduced usb charging. in addition to setting the high-level charge current, the hcp programming resistor also sets the termination current at 10% of th e constant current level and the conditioning current at 5% of the constant current level. power status indicators stat and ok dc can be configured to show charge in progress, battery fully charged and external power on. the stat pin is capable of sourcing or sinking 5ma. the ok dc output is an open drain output and can sink 10ma. the LX2208 enters a low quiescent current shut down when power is removed from the in pin or when it is logically shutdown to minimize battery drain. protection features include: under voltage lock out, reverse current blocking on the in pin, internal die temperature thermal loop to reduce charge current to maintain a safe die temperature, and a unsafe battery temperature charge inhibitor. for charging deeply discharged batteries, the controller includes a conditioning charge mode. the LX2208 comes in a 3x3mm 12 pin mlpd package. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? up to 2a charging current ? integrated power mosfet ? three charge levels for adapter, and usb hi and low ? charge battery from a current limited adapter ? 0.5% battery voltage accuracy ? usb current compliance ? battery full indicator ? cc/cv with thermal feedback ? battery temperature monitor ? precision charge termination ? protection features: o unsafe battery temp lockout o internal ic temp regulator o usb current limiter o reverse current blocking o under voltage lockout o false termination prevention under low supply conditions applications ? navigation devices ? multi-media players ? handheld devices ? digital cameras product highlight adapter or usb shutdown current programming status battery temperature lockout sensing in bat sd h/l hcp tmp dc ok stat gnd cmp battery lcp LX2208 usb hi/low 20% adapter or usb select charging full power on + - package order info ld plastic mlpd 3 x 3mm 12 pin t a ( c) rohs compliant / pb-free -40 to 85 LX2208ild note: available in tape & reel. append the lett ers ?tr? to the part num ber. (i.e. LX2208ild-tr)
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 absolute maximum ratings supply input voltage (in , bat) ...................................................................... -0.3 v to 7v all other pins ............................................................................................-0.3v to v supply battery charging current .............................................................................................2.5a operating ambient temperature range (t a ) ..................................................-40 to 125 c maximum operating junc tion temper ature .............................................................. 150 c storage temperat ure rang e.........................................................................-65 c to 150 c lead temperature (sol dering 10 s econds) ................................................................. 300 c peak temp. for solder reflow (40 s econds maximum expos ure).................. 260c (+0 -5) note: exceeding these ratings could cause damage to the device. all voltages are with respect to ground. currents are positive into, ne gative out of specified terminal. thermal data ld plastic micro leadframe package 12-pin thermal resistance - junction to a mbient , ja 33 c/w* junction temperature calculation: t j = t a + (p d x ja ). *the ja numbers are guidelines for the thermal performa nce of the device/pc-board system. all of the above assume no ambient airflow. see la yout guidelines section for important details. package pin out cmp h/l gnd dc ok 1 2 3 4 58 9 10 11 12 in stat bat lcp hcp tmp 20% 6 7 sd 2208 xxxx msc ld package (top view) rohs / pb-free 100% matte tin pin finish functional pin description name pin description bat 12 output, battery connection ? this pin is wired to the pos itive terminal of a single cell lithium ion/polymer battery. cmp 2 input, compensation ? connect a series combination of a 1k resistor and 0.47f capacitor from in to cmp. ok dc 4 output, power status logic pin and led driver ? this pin is an open drain output that can sink 10ma of current to drive an external led. this pin is low impedance to g nd when the in pin input voltage is high enough to charge the battery. gnd 7 common ground ? used as chip ground and as a reference for the battery return. hcp 10 input, high current programming and terminat ion current programming ? a resistor (r hcp ) between this pin and gnd sets the constant current high level. the following relationship determines the charging current of constant current mode: typically i bat =7150/r hcp when h/ l is high. the termination current is set to 1/10 of the hcp current level, and the conditioning current is set to 1/20 of the hcp current level. h/ l 8 high or low load select logic input ? a logic high selects the constant charge current level set by the hcp pin resistor r hcp and a logic low selects the constant charge current level set by the lcp pin resistor r lcp . in 1 input power ? connect to a wall adapter or a usb port. lcp 9 input, low current programming ? a resistor (r lcp ) between this pin and gnd sets the constant current low level. the following relationship determines the chargi ng current of constant current mode: typically i bat =7150/r lcp when h/ l is low and 20% is high. sd 5 input, shutdown ? a logic high places the LX2208 in shut down mode; it can also be used for usb suspend mode. stat 3 output, charging status logic pin and led driver ? this pin can source or sink 5ma of current to drive an external led in either output state. this pin is low when the battery is in charging mode and becomes high when the charge cycle is finished. it becomes high impedance when the input power is removed. tmp 11 input, battery temperature monitor ? this sense pin dete rmines the battery temperature. it is connected to a resistor network as defined in the application note. when the tmp pin falls below 29% (typ) of v in or rises above 74% (typ) of v in it suspends charging. ground the tmp pin if it is not used. 20% 6 20% select logic input ? this pin is only monitored when the h/ l pin is low. a logic high on 20% pin selects the constant charge current level set by the lcp pin resistor r lcp. a logic low selects 20% of the constant charge current level set by the lcp pin resistor r lcp .
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 electrical characteristics unless otherwise specified, the following specifications apply over the operating ambient temperature -40 c t a 85 c and the following test conditions: v in = 5.0v; v sd = low; v h/ l = high, v 20% = high; v bat = 3.6v; r hcp =15.8k, r lcp =15.8k; v tmp = 0v. LX2208 parameter symbol test conditions min typ max units ` input circuitry input voltage v in 4.35 5 6 v under voltage charging lockout v in(uvlo) rising input v bat = 2.8v 2.9 3.1 3.3 v in uvlo hysteresis 225 mv v bat = 4.2v (battery charged) 1 2 ma in input supply current i in sd = high (shutdown mode) 10 50 a ` battery charger constant voltage charging v bat i bat < 100ma @ 25c (4.5v to 5.5v) 4.18 4.2 4.22 v constant voltage charging v bat i bat < 100ma (4.5v to 5.5v) 4.16 4.2 4.24 v constant voltage charging v bat i bat < 100ma (4.35v to 6v) 4.10 4.2 4.24 v charge current i bat r hcp = 3.57k 1800 2000 2200 ma charge current i bat r hcp = 7.15k 900 1000 1100 ma charge current i bat r hcp = 15.8k 400 453 500 ma low level charge current i bat v h/ l = low 408 453 476 ma 20% charge current ratio i bat i( v 20% = low) / i ( v 20% = high ); v h/ l = low 18 20 22 % condition current i bat v bat < v cct ; r hcp = 3.57k 50 100 150 ma condition current i bat v bat < v cct ; r hcp = 7.15k 25 50 75 ma conditioning current threshold v bat rising battery voltage 2.5 2.7 2.9 v termination current i bat r hcp = 3.57k 250 ma termination current i bat r hcp = 7.15k 125 ma top off threshold v bat 0 c c 96 97 98 % top off threshold v bat -40 c c 96 97 98.5 % battery drain current i bat v bat = 4.2v (battery charged, v in > 4.5v) 5 15 a battery drain current i bat v bat > v in 5 15 a battery drain current i bat v sd =high (shutdown mode) 2.5 5 a ` logic stat high output v stat v in = 5.0v, i drv = -5ma 4.2 4.5 5 v stat low output v stat v in = 5.0v, i drv = 5ma 0.5 v input logic : sd, h/ l , 20% v log input logic threshold 450 725 1000 mv input current, v log = 2v 0 2.5 5 input current : sd, h/ l , 20% i log input current, v log = 0v -2 0 2 a logic hi output, 10k pull up to 3.3v 3.2 output logic : ok dc v log(out) logic low output, i log = 10ma 0.5 v ` battery temperature monitor cold threshold v tfb rising voltage 72 75 76.5 %v in cold threshold v tfb falling voltage 70.5 72 74 % v in hot threshold v tfb falling voltage 27 28 30 % v in hot threshold v tfb rising voltage 28 30 31 % v in tfb disable volt v tfb 70 100 150 mv
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 simplified block diagram 1 in 12 bat charge control 7 gnd high charging current 10 hcp temperature control constant voltage control charge termination control enable 5 sd uvlo + - 3 stat low charging current 9 lcp 8 h/l dcok 11 tmp cond. current conditioning threshold 6 20% 4 2 cmp
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 control logic diagram start v in > v bat yes sleep no v bat >60% condition charge mode no yes constant current charge mode temp < 130oc reduce charge current i cc < i max yes reduce charge current yes no no v bat > v cv constant voltage charge mode yes no i bat v bat =0 if v in < v bat
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 application circuits adapter or usb power pin shutdown current programming status battery temperature lockout sensing in bat sd h/l hcp tmp dc ok stat gnd cmp battery lcp 2..4k 2.4k 2.4k 3.57k 15.8k 24.9k 121k 0.47u grounded pin in usb cable. leave open in adapter cable. 10k LX2208 usb hi/low 20% 1k charging full power on + - figure 1 ? typical application ? 2a adapter charge current and 500ma or 100ma maximum usb charge currents. a grounded spare pin in the usb power cable can be used to sense when the 500ma usb current power source is being used. this application also uses three led indicators for power attached, battery charging and battery full. this configuration also implements circuitry to lockout battery charging if the battery is less than 0oc or greater than 60c.
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 theory of operation g eneral d escription the LX2208 charges a single cell lithium ion or lithium polymer battery using two steps: a constant current mode followed by a constant voltage mode. the maximum charging current during the constant current mode of the charging profile can be logically set (using h/ l pin) to two resistor-programmable levels. the resistor r hcp connected between hcp and gnd pin sets the higher level curr ent. the resistor r lcp connected between lcp and gnd pin sets the lower level current. there is also a 20% logic input that selects either the full current set by the lcp resistor r lcp or 20% of that value. the charger will terminate constant voltage charging once the current drops below the ta per current setting which is 10% of the high charge current setting (determined by hcp resistor r hcp value). c onditioning c urrent c harge m ode a conditioning current is applied to batteries that are deeply discharged and have a terminal voltage less than 60% of the constant voltage level. the conditioning current is 5% of the hcp programmable constant current level. once the battery terminal voltage exceeds the conditioning current threshold, the full constant current level is applied (unless charging current is limited by one of the other charger control loops). c harge t ermination m ode to increase system battery life and avoid float charging, the LX2208 disconnects the charger once the battery has been fully charged. the charge termination state occurs at the end of constant voltage mode. the termination current is set by the value of the resistor r hcp connected between hcp pin and gnd. the stat pin changes state when charging is completed. t op o ff c harge m ode once the charger has completed a charge cycle, if power remains applied, the LX2208 enters a voltage monitoring mode. in this mode, the LX2208 monitors the battery terminal voltage and applies a top off charge if the battery voltage drops below the top off threshold. a dapter or usb s election the LX2208 supports battery charging from a system that provides adapter power or usb power using the same external connector. figure 1 shows one example of a system using a special usb adapter cable to determine whether the power source is usb or wall adapter. similarly, if the system pro cessor senses the absence of usb data, it can logically set the h/ l logic level high to allow a higher charge current to be used. i nput s upply q ualification if the input supply is not high enough for the internal 4.2v reference to operate, charge termination will be prevented. this may be useful if supply is severely current limited. usb c harge m ode and c urrent l imit the LX2208 is fully compliant with, and supports, the usb specifications ? the low power peripheral (100ma) and high power peripherals ( 500ma). usb current levels can be set using the appropriate values of the lcp programming resistor r lcp . 20% logic input selects usb high/low charge current. when the sd pin is pulled high, the usb input enters shut down mode and will not present a load to the in pin. ok dc the in input is monitored and ok dc is set to a logic low to report the presence of the power source with sufficient voltage to charge the battery. the ok dc threshold is the larger of the uvlo threshold or the battery voltage. p rotection f eatures conditioning current mode ? if the battery terminal voltage is less than 2.7v, the battery charger will reduce the charge current to 5%. this al so protects the appliance from overheating by trying to drive the full charging current into a short circuited battery. under voltage lockout ? the charge cycle will not start until the in voltage rises above 3.1v. hysteresis helps alleviate chattering on and off. thermal control loop ? if the power dissipation of the charger becomes excessive, the charge current will be linearly reduced to prevent the die temperature from getting above 140 c. this does not cause the charge cycle to stop. reverse current blocking ? if in input is grounded, current will not flow from the bat pin through the charger. no external blocking diode is required on the input. shut down mode ? if the sd pin is asserted a logic high, the charger enters a shut down mode where a very low quiescent current prevents drain from the battery.
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 application note l ayout in the layout of the printed circuit board (pcb) it is important to provide a low thermal impedance path from the thermal pad on the bottom of the LX2208 package to the ground plane of the circu it board to maximized heat dissipation. generally this is accomplished by the use of multiple thermal vias. this insures the LX2208 stays cool and can provide the maximum charge current to minimize the time required to charge the battery. for latch-up prevention purpose, it is important to place 10f capacitors (x5r or x7r di electric) close to the in and bat pins. with long input cables to the adapter or usb, it is best to use a sheathed cable or twisted wire cable which is typical of most applications. the cmp 0.47f capacitor and 1k resistor should be placed close to the cmp pin and in pin; the cmp pin is located adjacent to the in pin to facilitate this. c urrent p rogramming r esistors the LX2208 has two programming resistors to control the battery charging current during the constant current charging mode of the battery charging cycle. when the h/ l pin is high (selecting the high current charging mode), the charge current is determined by the value of the hcp programming resistor r hcp . the maximum charge current is determined by the programming current at either the hcp or lcp programming pins (depending on the state of h/ l ); the range of each of thes e channels is identical. the programming current is the hcp or lcp pin voltage (typically 1.25v) divided by the value of the programming resistor. for example, th e hcp current with a 7.15k resistor to gnd is: a 75 1 7.15k 1.25 r 1.25 i hcp hcp = = = charge current vs ihcp (or ilcp) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0 50 100 150 200 250 300 350 ihcp (in ua) charge current (in ma) using the table above it can be seen that for a programming current value of 175a, the corresponding maximum charge current is 1a. the termination current determines the point at which the charge cycle is terminated and the battery is determined to be fully charged. the termination current is determined by the value of the hcp programming current as determined by the hcp programming resistor r hcp . for a value of i hcp = 175a (as was used in the previous example), the termination curr ent from the chart below can be seen to be 100ma. termination current vs ihcp 0 20 40 60 80 100 120 140 160 180 200 0 50 100 150 200 250 300 350 ihcp (in ua) termination current (in ma) the termination current is always roughly 10% of the maximum charge current set by the hcp resistor r hcp . constant charge current (in ma) r hcp 43.3 169.28k 92 88.67k 460 15.80k 730 9.75k 1000 7.15k 2000 3.56k* * r hcp minimum value termination current (in ma) r hcp 4.33 169.28k 9.2 88.67k 46 15.80k 73 9.75k 100 7.15k 200 3.56k*
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 application note b attery t emperature m onitor the LX2208 has an input to monitor the battery temperature during battery charging; this method assumes the battery pack contains a thermistor expressly for this purpose. a typical lithium ion battery should only be charged within a temperature range of 0 c to 60 c. for this calculation, a vishay nths0402n01n1003j thermistor was used. this thermistor has the value of 327k ? at 0 c, 100k ? at 25 c and 24.9k ? at 60 c. the thermistor must be biased with a thevenin voltage source and series resistance to achieve the proper tmp thresholds. a fixed value resistor is added in series with the thermistor to prevent it from becoming too low impedance at high temperatures and causing the tmp input to default to off. v th r th r ntc r min tmp using a value of r min that is equal to the thermistor temperature at 60 c works well; therefore, for this example, set the value of r min to 24.9k. this has the effect of adding 24.9k to the thermistor resistance values so it becomes 352k ? at 0 c, 125k ? at 25 c and 49.8k ? at 60 c. the equations for r th and v th are, using cold temperature fault threshold average of 74% and the hot temperature fault threshold average of 29% of v in : () ()( ) 0.99 k r 0.74 r 0.29 r r 0.74 0.29 v v c 60 t c 0 t c 60 t c 0 t in th = = ? ? = = = = = 121k r 1 0.74 k r c 0o t th = ? ? ? ? ? ? ? = = where r at temperature is the sum of the thermistor plus r min . to finish the design it is necessary to create the thevenin voltage and resistance using a voltage divider from the input pin (in). v in r1 r ntc r min tmp r2 the values of r1 and r2 can be calculated as: 122k k r r1 th = = 14,800k r r r r r2 th 1 th 1 = ? = in this case, it is not neces sary to use r2, because the value is so large it is insignificant. in this case, r1 = r th . the final circuit for this example is: v in 121k r ntc 24.9k tmp the tmp voltages with this circuit are: temp (c) r ntc v tmp (% v in ) -20 971k 89% 0 327k 74% 25 100k 51% 60 24.9k 29% 80 12.6k 24% at the trip point threshold, there may be chattering on and off of the charging cu rrent. however, as the temperature increases or decreases further from the trip point threshold, the chattering will stop.
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 10 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 application note p ower s tatus i ndicators the stat pin is designed to source or sink current. leds can be configured to indicate charging or battery full. the battery full indicator can be connected to ok dc rather than gnd to insure it is off when the input power is removed and the stat pin and ok dc pin go to a high impedance state. conditions stat charge in process low charge completed high input power removed hi z charging profile conditioning current battery charging usb high level 3.90 3.95 4.00 4.05 4.10 4.15 4.20 4.25 0.0 60.0 120.0 time in minutes battery v oltage 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 battery cuurent vbat ibat conditioning current vs ihcp 0 20 40 60 80 100 0 50 100 150 200 250 300 350 ihcp (in ua) conditioning current (in ma)
LX2208 p roduction d ata s heet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 11 www. microsemi . com 2 amp three level lithium ion battery charger tm ? l l x x 2 2 2 2 0 0 8 8 copyright ? 2007 rev. 1.0, 2007-04-03 package dimensions ld 12-pin plastic mlp dual exposed pad e d e a3 a1 a e2 d2 l pin 1 id k b m illimeters i nches dim min max min max a 0.80 1.00 0.031 0.039 a1 0.00 0.05 0.000 0.002 a3 0.20 ref 0.008 ref d 3.00 bsc 0.118 bsc e 3.00 bsc 0.118 bsc d2 1.87 2.12 0.074 0.083 e2 1.06 1.31 0.042 0.052 e 0.45 bsc 0.018 bsc k 0.20 min 0.008 min l 0.30 0.50 0.012 0.020 b 0.15 0.25 0.006 0.010 note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.1 55mm(.006?) on any side. lead dimension shal l not include solder coverage. production data ? information contained in this document is proprietary to microsemi and is current as of publication date. this document may not be modified in any way without the express written consent of microsemi. product processing does not necessarily include testing of all parameters. microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time.

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