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lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? description the lx2201 linear battery charger is a 2-stage multi-state l-ion battery charger (constant current/constant voltage) that can supply up to 2a of charging current into a single cell lithium-ion battery. while the lx2201 is a general-purpose charger, it features several built in programming states specifically for compliance with usb bus specifications. monitoring the input current supplied by the system and then dynamically allocating any unused power to the charging circuitry maintains usb compliance with respect to peripheral current limitations. this feature insures that the battery will be charged as soon as possible without sacrificing system performance or features. the lx2201 is a highly integrated charger that requires just three external programming resistors; one for setting the constant charge current level, one for setting the termination charge current, and one for setting the vin maximum current. it also has an internal thermostat that will throttle back the charge current to keep the die temperature from exceeding 150c; this feature insures the lx2201 delivers the maximum charge rate for a given thermal environment. a logic input is provided to select either 4.1v or 4.2v battery chemistries. a high accuracy current sensing circuit is implemented allowing batteries to be filled to the fullest capacity before terminating the charge cycle. since the battery terminal voltage is separated from the system load when charging from an adapter, trickle charging, which can prematurely age the li-ion battery, is avoided. the lx2201 provides a charging status indicator. the integrated pmos pass element features low drop out voltage while providing an inherent load disconnect with virtually no drain on the battery when disabled or when the input power is removed. additionally a battery load disconnect switch has been integrated providing seamless power switching when transitioning between charge and discharge. the lx2201 features a pre-charge conditioning mode for batteries that have been deeply discharged and also has a top off charge mode for batteries that are left on the charger for extended periods. the lx2201 is packaged in a high power 20-pin mlp 4x4 mm miniature surface mount package. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? usb compliant charging states ? small, high power 20-lead mlp package ? internal pass element can function as a reverse direction load switch ? no sense resistor required ? full capacity charging ? always cool running ? 4.1 or 4.2v applications ? tolerates 5v + 10% wall supply regulation ? conditioning mode for deep discharge ? built in mosfet driver for easy ac adapter/usb implementation ? topping charge for long periods of non-use. ? inherent load disconnect applications ? batteries with 350mah to 2ah ratings ? cell phones ? pdas ? charging cradles ? digital cameras ? low cost single l-ion cell chargers product highlight ac/dc adapter to system regulator usb power usb lo / hi lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat state select truth table vid0 vid1 vdd > vbat vbat > vdd 0 0 switch open ? charging disabled. switch open ? discharge disabled. 0 1 charging ? usb high level if using v in. switch open ? discharge disabled. 1 0 charging ? usb low level if using v in. battery discharging. mosfet fully enhanced with current flow vbat to vdd. 1 1 charging ? usb high level if using v in. battery discharging. mosfet fully enhanced with current flow vbat to vdd. package order info t a ( c) lq plastic mlp 4x4mm 20-pin 0 to 70 LX2201CLQ note: available in tape & reel. append the letter ?t? to the part number. (i.e. LX2201CLQt) l l x x 2 2 2 2 0 0 1 1
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? absolute maximum ratings supply voltage (vin )..........................................................................-0.3v to 7v analog input signals (vidx, vm, sns) .............................................-0.3v to 7v battery charging current (i bat ).........................................................................2a discharge current (i vdd )....................................................................................3a operating junction temperature.................................................................. 150 c storage temperat ure range...........................................................-65 c to 150 c lead temperature (soldering 180 seconds) ................................................ 235 c vin maximum dc current .........................................................................500ma vin maximum surg e current ............................................................................2a note: exceeding these ratings could cause damage to the device. all voltages are with respect to ground. currents are positive into, negative out of specified terminal . thermal data lq plastic micro lead frame quad package 20-pin thermal resistance - junction to a mbient , ja 40 c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the thermal performan ce of the device/pc-board system. all of the above assume no ambient airflow. package pin out cmp lq p ackage (top view) n.c. ? no internal connection n/u ? not used rsvd ? do not use functional pin description name description bat charging output - this pin is wired to the positive terminal of the battery. (t he negative battery terminal is wired to gn d.) ccp charge current programming pin - a resistor (rcp) is connec ted between this pin and gnd. the constant current is determined by the following relationship: r c p i max bat 75000 ) ( = cmp compensation pin ? connect a 0.1uf compens ation capacitor from this pin to vdd. ctp charge termination programming pin ? a resistor (rtp) is connected between this pin and gnd. the termination charge current is determined by the following relationship: r t p i min bat 7500 ) ( = cus maximum vin current programming pin ? a resistor (rus) is connected between this pin and gnd. the hi level charge current is determined by the following relationship: r u s i hi in 1250 )) ( = gnd common ground nc not connected. this pin is connected internally and should be left floating. psw pmos switch driver ? this output is designed to drive the gate of an external pmos power switch. the driver is pulled low (pmos on state) when vdd > vbat. vdd common power node ? connects to system power bus. vidx state select input ? applying a two bit ttl compatible signal sets the desired state of the charger corresponding to the truth table. vin voltage input ? current limited usb input. apply a usb compliant power input. vm voltage mode select - selects the constant voltage charge level. wired to vin for 4.1v and gnd for 4.2v. stat status - this pin is a logic high level when the battery is being charged. a low signal indicates either under voltage lockout, charge completed, or vbat > vd d, or vid0 = vid1 = 0. p p a a c c k k a a g g e e d d a a t t a a
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? electrical characteristics unless otherwise specified, the following specificati ons apply over the operat ing ambient temperature 0 c t a 70 c except where otherwise noted and the following test conditions:. lx2201 parameter symbol test conditions min typ max units ` main circuitry input voltage v dd 4.5 6 v v dd > v bat 4 8 ma quiescent current i gnd v dd < v bat 3 5 a ctp bias voltage v ctp r ctp = 150k, i bat > 100ma 1.25 v ccp bias voltage v ccp 1.25 v cus bias voltage v cus 2.5 v ` constant voltage mode vm = hi 4.16 4.2 4.24 constant current charge voltage v ccl vm = lo 4.06 4.1 4.14 v maximum dropout voltage v in ? v bat i bat = 1a 300 mv top off charge droop threshold v drp 96 97 98 bat cvl v % v ` constant current mode bat constant current accuracy i ccl r ccp = 75k 0.9 1 1.1 a bat constant current level i bat v bat < (v cvl ? 100mv) 0.35 2 a conditioning current i cond v bat < v ctv 4 5 6 bat ccl i % i conditioning current mode threshold voltage v ctv 55 60 65 bat cvl v % v charge termination current accuracy i bat r ctp = 150k 40 50 60 ma ` usb current limit usb low current limit i in v in = 5v, v dd < v in , vid1 = lo, r usb = 2.5k 90 95 100 ma usb high current limit i in v in = 5v, v dd < v in , vid1 = hi, r usb = 2.5k 450 475 500 ma ` logic stat logic high output v stat v in = 5.0v, i stat = -5ma 4.5 5 v stat logic low output v stat v in = 5.0v, i stat = 100a 0.8 v logic hi 2.0 state select threshold v vid logic lo 0.8 v logic hi 2.0 vm select threshold v vm logic lo 0.8 v ` thermal shutdown maximum junction temperature t j v in = 5.0v, i out = 1a, temperature rising 130 140 150 c ` bi-directional pass element control discharge switch on resistance r ds(on) i bat = -1a 130 150 m ? ` psw fet driver high output voltage v psw v in > v bat , i psw = 0 4.75 5 v low output voltage v psw v in > v bat , i psw = 0 0 0.2 v or-ing resistance r psw 5 10 20 k ? e e l l e e c c t t r r i i c c a a l l s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? simplified block diagram vin 0.1 vdd bat charge/ discharge control gnd constant current control ccp temperature control constant voltage control usb limit control cus vm charge termination control ctp vid1 vid0 psw stat cmp figure 1 ? simplified block diagram b b l l o o c c k k d d i i a a g g r r a a m m
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? application circuits start v dd > v bat yes discharge mode no v bat >60% condition charge mode no yes constant current charge mode temp < 140 reduce charge current i in < i usb yes reduce charge current yes no no v bat > v cv constant voltage charge mode yes no i bat vbat or vidx change state. return to the top of the chart. lx2201 control flow diagram vid0 = 1 yes switch off no i usb determined by the state of vid1. vid0 = 1 yes no vid0 = 1 yes no figure 2 ? control flow diagram a a p p p p l l i i c c a a t t i i o o n n s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? application schematics ac/dc adapter usb power usb lo / hi lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat to system power bus 150k 2.5k 75k 0.1uf 10uf 10uf ac/dc adapter off / on lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat to vdd to system power bus 10uf 150k 2.5k 75k 0.1uf 10uf figure 3 ? ac adapter and usb supply (charge and discharge modes) figure 4 ? ac adapter (charge and discharge modes) ac/dc adapter off/on charge indicator lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat to vdd 150k 2.5k 75k 0.1uf 10uf 10uf 1.0k usb power usb lo /hi lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat figure 5 ? ac adapter supply only (charge only mode) with charging indicator figure 6 ? usb supply only (charger only mode) a a p p p p l l i i c c a a t t i i o o n n s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? application schematics (continued) ac/dc adapter off / on lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat to vdd dmmt3906w to bat 576k 499k 499k 499k 100k to system power bus 150k 2.5k 75k 0.1uf 10uf 10uf figure 7 ? ac adapter with charging voltage headroom regulati on (for use with a current limited power supply). lx2201 nc vid1 vid0 vm psw vdd vin vdd bat bat cus ctp ccp gnd bat bat cmp vdd vdd stat to vdd dmmt3906w to bat 576k 499k 499k 100k to system power bus 150k 2.5k 75k 0.1uf 10uf 10uf ac/dc adapter usb power + - 1k 499k 124k 2n7002 0.1 irlms6802 irlms6802 ups5817 1n4148 b220 mcp6001 to vid1 499k to psw usb lo / hi figure 8 ? current limited usb interface with isolated battery and bi-directional pass element. a a p p p p l l i i c c a a t t i i o o n n s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? theory of operation g eneral d escription the lx2201 is designed to charge a single cell lithium ion battery using two steps, a constant current step followed by a constant voltage step. the basic charger function uses the vdd pins as an input and bat pins as the output. this basic charger has a programmable maximum current (programmabl e by the resistor value between pin ccp to gnd) which is the maximum charging current during the consta nt current mode of the charging profile. the low dr opout of the pass element allows the battery to be charged from a loosely regulated power supply. in the constant voltage mode of the charging profile the battery terminal voltage can be regulated to 4.1v or 4.2v by strapping the vm pin to vdd or gnd, respectively. the ch arger will terminate constant voltage charging once the current drops below the minimum current setting (progr ammable by the resistor value between pin ctp to gnd). in the conditioning charge mode 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 ccp programmable constant current level (except where it might be limited in the usb states). once the battery terminal voltage exceeds the 60 % level, the full constant current level is applied (unless charging current is limited by one of the other charger control loops). the lx2201 has a built in thermostat that will throttle back the charging current to prevent the internal die temperature from exceeding 150oc. this feature prevents the ic from getting hot enough to damage the board. this feature can reduce the settings dictated by the constant voltage and constant current control loops to reduce power dissipation in the ic. the lx2201 will turn off the pass element once the battery has been fully charged. this is to prevent float charging, which has been shown to reduce lithium ion battery life. the charge termination state occurs at the end of the constant voltage charge mode where the battery draws less current as it near s full capacity. the high precision of the lx2201 in low current state lets the battery continue charging to the point where the charging current has dropped to the charge termination current set by the charge termination programming pin. once the charger has completed a charge cycle, if power remains applied, the lx2201 enters a voltage monitoring mode. in this mode the lx2201 monitors the battery terminal voltage and applies a top off charge if the battery voltage drops by more than 3% of full scale. this feature is especially im portant for charging systems in emergency equipment were usage is infrequent. the usb states insure compliance with the usb specification. there are two current limitations imposed by the specification; a low power peripheral is to draw less than 100ma unless configure by the host controller as a high power peripheral which increases the current limitation to 500ma. while the lx2201 will not negotiate the host for the power designation it must insure that the total current through vin is less than, or equal to, the stated current limitation. to accomplish this the constant current loop will sense the current through vin and dynamically scale i bat to maintain the desired input current. it must be noted that the circuit does not limit the input current and only scales the charging current. it is possible that a system would draw more than 100ma through vdd, and as a result fail usb compliance. in this case the lx2201 would have s caled the charging current to zero. this feature allows for the fastest possible charge time in a usb configuration by allocating unused power for the charger without limiting system performance or features. the lx2201 has two unique features which assist in the power control design. th e pass element can be programmed by the vid0 pin to be bi-directional. this allows the pass element to be used as a power switch to provide a low impedance path around the oring diode without the need to use an external mosfet. the other feature is a logic output that enhances an external pmos fet when the lx2201 is in a charging mode (ie vdd > vbat). this provides a low impedance path around the oring diode that is typically used in a multiple source power distribution. lowering the voltage drop across the oring diode is especially helpful for use with low voltage power inputs such as usb. a a p p p p l l i i c c a a t t i i o o n n s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? application note c urrent l imited p ower s upplies when using input power supplies that are current limited or have a high source impedance, the battery charging current and/or load current can pull the vdd pin down very close to the battery terminal voltage. this may cause the lx2201 to enter an indeterminate state where it switches between charge and discharge modes. to prevent this, the pnp differential amplifier circuit of figure 7 can be added; this circuit adds an additional control loop that regulates the charger headroom to 300mv by scaling back the battery charging current. the internal power switch within the lx2201 requires the power supply have a minimal level of strength to switch from discharge mode to charge mode. if the power source is severely current limited, the lx2201 may not open the discharge switch. in this ca se, a small amount of current will be allowed to flow into the battery unregulated. if left in this state indefinitely, the current will eventually raise the battery terminal voltage to the point where the batteries internal protection circuitry will open the circuit. typically, the lx2201 requires a minimum of 80ma in usb mode and 200ma using the vdd input to force the switchover to charge mode. alternatively, if weak power sources are used, the switchover from discharge to charge mode can be forced by momentarily setting vid0 and vid1 to a low state, which will open the discharge switch allowing the vdd voltage to rise so the lx2201 can enter charge mode. usb c ompliance to be compliant with the usb specification, the +5v current must be less than 100ma in the low power mode and less than 500ma in the high power mode. if the lx2201 is configured as shown in figure 3, it is possible for the system to consume more than the maximum allowed usb current (in whic h case the battery charging current will have been fully s caled back). if it is not possible to regulate the load current when charging from a usb power source and strict adherence to the usb power budget is required, the lx2201 configuration as shown in figure 6 can be used. in this case the system load can be applied directly to the battery and the lx2201 will prevent the load + battery from drawing more power than is allowed for usb compliance. a better approach that provides battery isolation is shown in figure 8; in this approach, the op amp circuit prov ides a current limiter that prevents the system from exceeding the usb power limits. the battery is only discharged if the ac adapter or usb inputs are removed or current limited. l ayout g uidelines ? it is important when laying out the lx2201 to place 10uf ceramic capacitors close to the vdd and vbat ic terminals to filter switching transients. ? it is important to provide a low thermal impedance path from the thermal pad on the bottom of the lx2201 package to the gr ound plane of the circuit board to maximize the heat dissipation. a a p p p p l l i i c c a a t t i i o o n n s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 10 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? package dimensions lq 20-pin mlpq plastic 4x4mm (114x114dap) e a e b e2 d2 l d a3 a1 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 b 0.18 0.30 0.007 0.088 d 4.00 bsc 0.157 bsc d2 2.59 2.79 0.102 0.110 e 4.00 bsc 0.157 bsc e2 2.59 2.79 0.102 0.110 e 0.50 bsc 0.019 bsc l 0.30 0.50 0.011 0.019 note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006?) on any side. lead dimension shall not include solder coverage. m m e e c c h h a a n n i i c c a a l l s s
lx2201 p reliminary d ata s heet microsemi integrated products division 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 11 copyright ? 2000 rev. 0.6a, 2004-01-26 www. microsemi . com usb li-ion battery charger tm ? notes product preliminary data ? information contained in this document is pre-production data, and is proprietary to microsemi. it may not be modified in any way without the express written consent of microsemi. product referred to herein is not guaranteed to achieve preliminary or production status and product specifications, configurations, and availability may change at any time. n n o o t t e e s s

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