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1 ? fn6430.0 isl9203a li-ion/li polymer battery charger the isl9203a is an integrated single-cell li-ion or li-polymer battery charger capable of operating with an input voltage as low as 2.4v. this charger is designed to work with various types of ac adapters. the isl9203a operates as a linear charger when the ac adapter is a voltage source. the battery is charged in a cc/cv (constant current/const ant voltage) profile. the charge current is programmable with an external resistor up to 1.5a. the isl9203a can also work with a current-limited adapter to minimize the thermal dissipation, in which case the isl9203a combines the benefits of both a linear charger and a pulse charger. the isl9203a features charge current thermal foldback to guarantee safe operation when the printed circuit board is space limited for thermal dissipation. additional features include preconditioning of an over-discharged battery and thermally enhanced dfn package. typical application circuit features ? complete charger for single-cell li-ion batteries ? very low thermal dissipation ? integrated pass elemen t and current sensor ? no external blocking diode required ? 1% voltage accuracy ? programmable current limit up to 1.5a ? charge current thermal foldback ? accepts multiple types of adapters ? guaranteed operation down to v in = 2.65v after start up ? ambient temperature range: -20 c to +70 c ? thermally-enhanced dfn packages ? pb-free plus anneal available (rohs compliant) applications ? handheld devices including medical handhelds ? pdas, cell phones and smart phones ? portable instruments, mp3 players ? self-charging battery packs ? stand-alone chargers ? usb bus-powered chargers related literature ? technical brief tb363 ?guidelines for handling and processing moisture sensit ive surface mount devices (smds)? ? technical brief tb379 ?thermal characterization of packaged semiconductor devices? ? technical brief tb389 ?pcb land pattern design and surface mount guidelines for qfn packages? ordering information part number (note) part marking temp. range (c) package (pb-free) pkg dwg. # isl9203acrz 03acz -20 to +70 10 ld 3x3 dfn l10.3x3 ISL9203ACRZ-T 10 ld 3x3 dfn tape and reel note: intersil pb-free plus anneal products employ special pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are rohs compliant and compatible with both snpb and pb-free soldering operations. intersil pb-free products are msl classified at pb-f ree peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jedec j std-020. vbat vin 5v input isl9203a c 1 v2p8 en gnd iref vsen status time c time floating to enable c 2 c 3 r iref r 1 pinout isl9203a (10 ld 3x3 dfn) top view vin status time gnd vbat vsen iref v2p8 en 2 3 4 1 5 9 8 7 10 6 nc data sheet february 14, 2007 caution: these devices are sensitive to electrosta tic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright ? intersil americas inc. 2007. all rights reserved. all other trademarks mentioned are the property of their respective owners.
2 fn6430.0 february 14, 2007 absolute maximum rati ngs thermal information supply voltage (vin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 7v output pin voltage (bat, vsen, v2p8). . . . . . . . . . . . -0.3v to 5.5v signal input voltage (time, iref). . . . . . . . . . . . . . . . -0.3v to 3.2v output pin voltage (status) . . . . . . . . . . . . . . . . . . . . . -0.3v to 7v charge current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6a esd rating human body model (per mil-std-883 method 3015.7) . . .4500v machine model (per eiaj ed-4701 method c-111) . . . . . . . .200v recommended operating conditions ambient temperature range . . . . . . . . . . . . . . . . . . .-20c to +70c supply voltage, vin . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3v to 6.5v thermal resistance (typical, notes 1, 2) ja (c/w) jc (c/w) 3x3 dfn package . . . . . . . . . . . . . . . . 46 4 maximum junction temperature (plastic package) . . . . . . . +150c maximum storage temperature range . . . . . . . . . .-65c to +150c maximum lead temperature (soldering 10s) . . . . . . . . . . . . +300c caution: stresses above those listed in ?absolute maximum ratings? may cause permanent damage to the device. this is a stress o nly rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. + 150c max junction temperature is intended for short periods of ti me to prevent shortening the lifetime. operation close to +15 0c junction may trigger the shutdown of the device even before +150c, since th is number is specified as typical. notes: 1. ja is measured in free air with the component mounted on a high ef fective thermal conductivity te st board with ?direct attach? fe atures. see tech brief tb379. 2. jc , ?case temperature? location is at the center of the exposed metal pad on the package underside. see tech brief tb379. electrical specifications typical values are tested at v in = 5v and +25c ambient temperature, maximum and minimum values are guaranteed over 0c to +70c ambient temperature with a supply voltage in the range of 4.3v to 6.5v, unless otherwise noted. parameter symbol test conditions min typ max units power-on reset rising vin threshold 3.0 3.4 4.0 v falling vin threshold 2.3 2.4 2.65 v standby current vbat pin sink current i standby vin floating or en = low - - 3.0 a vin pin supply current i vin vbat floating and en pulled low - 30 250 a vin pin supply current i vin vbat floating and en floating - 1 2 ma voltage regulation output voltage v ch 4.158 4.20 4.242 v dropout voltage vbat = 3.7v, charge current = 1a - 320 550 mv charge current constant charge current (note 3) i charge r iref = 80k , v bat = 3.7v 0.9 1.0 1.1 a constant charge current i charge r iref = 1.21m , v bat = 3.7v 33 66 100 ma trickle charge current i trickle r iref = 80k , v bat = 2.0v 85 110 135 ma trickle charge current i trickle r iref = 1.21m , v bat = 2.0v 2 7 15 ma end-of-charge threshold i min r iref = 80k 85 110 135 ma end-of-charge threshold i min r iref = 1.21m 2-30ma recharge threshold recharge voltage threshold v rechrg 3.85 4.00 4.10 v isl9203a
3 fn6430.0 february 14, 2007 trickle charge threshold trickle charge threshold voltage v min 2.1 2.3 2.5 v v2p8 pin voltage v2p8-pin voltage v v2p8 2.7 2.9 3.1 v temperature monitoring charge current foldback threshold (note 4) t fold -100- c current foldback gain (note 4) g fold -100-ma/c oscillator oscillation period t osc c time = 15nf 2.4 3.0 3.6 ms logic outputs status logic low sink current pin voltage = 0.8v 5 - - ma status leakage current v vin = v status = 5v - - 1 a en input logic high 2.0 - 3.3 v en input logic low --0.8v en pin current when driven low - - 100 a notes: 3. the accuracy includes all errors except the programming resistance tolerance. the ac tual charge current may be affected by th e thermal foldback function if the thermal dissipatio n capability is not enough or by the on resistance of the power mosfet if the charge r input voltage is too close to the output voltage. 4. guaranteed by characterization. electrical specifications typical values are tested at v in = 5v and +25c ambient temperature, maximum and minimum values are guaranteed over 0c to +70c ambient temperature with a supply voltage in the range of 4.3v to 6.5v, unless otherwise noted. (continued) parameter symbol test conditions min typ max units typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r iref = r imin = 80k , v bat = 3.7v, unless otherwise noted. figure 1. charger outp ut voltage vs charge current figure 2. charger output voltage vs temperature 4.1975 4.1980 4.1985 4.1990 4.1995 4.2000 4.2005 4.2010 4.2015 0 0.3 0.6 0.9 1.2 1.5 charge current (a) r iref = 40k v bat (v) 4.190 4.192 4.194 4.196 4.198 4.200 4.202 4.204 4.206 4.208 4.210 0 20 40 60 80 100 120 temperature (c) charge current = 50ma v bat (v) isl9203a
4 fn6430.0 february 14, 2007 figure 3. charger output voltage vs input voltage charge current is 50ma figure 4. charge current vs output voltage figure 5. charge current vs ambient temperature figure 6. charge current vs input voltage figure 7. v2p8 output vs input voltage figure 8. v2p8 output vs its load current typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r iref = r imin = 80k , v bat = 3.7v, unless otherwise noted. (continued) 4.10 4.15 4.20 4.25 4.30 4.2 4.5 4.8 5.1 5.4 5.7 6 6.3 charge current = 50ma v bat (v) v in (v) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 3.0 3.2 3.4 3.6 3.8 4.0 2a 1.5a 1a 0.5a charge current (a) v vbat (v) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0 20 40 60 80 100 120 1.5a 1.0a 0.5a temperature (c) charge current (a) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 4.3 4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 6.1 6.3 6.5 1.5a 1a 0.5a charge current (a) v in (v) 2.920 2.922 2.924 2.926 2.928 2.930 3.5 4.0 4.5 5.0 5.5 6.0 6.5 v2p8 pin loaded with 2ma v in (v) v 2p 8 v o l t a g e ( v ) 2.70 2.75 2.80 2.85 2.90 2.95 0246810 v2p8 load current (ma) 3.00 v2p8 voltage (v) isl9203a
5 fn6430.0 february 14, 2007 figure 9. r ds(on) vs temperature at 3.7v output figure 10. r ds(on) vs output voltage using current limited adapters figure 11. reverse current vs temperature figure 12. input quiescent current vs temperature figure 13. input quiescent current vs input voltage when shutdown figure 14. input quiescent current vs input voltage when not shutdown typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r iref = r imin = 80k , v bat = 3.7v, unless otherwise noted. (continued) 200 250 300 350 400 450 500 550 600 650 700 0 2040 6080100120 temperature (c) thermal foldback starts near +100c r ds(on) (m ) 260 280 300 320 340 360 380 400 420 3.0 3.2 3.4 3.6 3.8 4.0 v bat (v) 500ma charge current, r iref = 40k r ds(on) (m ) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0 20 40 60 80 100 120 temperature ( c) v bat leakage current (a) 0 5 10 15 20 25 30 35 40 45 50 0 20406080100120 temperature ( c) en = gnd v in quiescent current (a) 10 12 14 16 18 20 22 24 26 28 30 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 en = gnd v in quiescent current (a) v in (v) 32 0.80 0.85 0.90 0.95 1.00 1.05 1.10 4.3 4.6 4.9 5.2 5.5 5.8 6.1 6.4 both vbat and en pins floating v in quiescent current (ma) v in (v) isl9203a
6 fn6430.0 february 14, 2007 pin descriptions vin (pin1) vin is the input power source. connect to a wall adapter. nc (pin 2) no connection for this pin. status (pin 3) status is an open-drain output indicating charging and inhibit states. the status pin is pulled low when the charger is charging a battery. it will be forced to high impedence when the charge current drops to i min . this high impedence mode will be latched until a recharge cycle or a new charge cycle starts. time (pin 4) the time pin determines t he oscillation period by connecting a timing capacitor between this pin and gnd. the oscillator also provides a time reference for the charger. gnd (pin 5) gnd is the connection to system ground. en (pin 6) en is the enable logic input. connect the en pin to low to disable the charger or leave it floating to enable the charger. v2p8 (pin 7) this is a 2.8v reference voltage output. this pin outputs a 2.8v voltage source when the input voltage is above por threshold, otherwise it outputs zero. the v2p8 pin can be used as an indication for adapter presence. iref (pin 8) this is the programming input for the constant charging current. it maintains at 0.8v when the charger is in normal operation. vsen (pin 9) vsen is the remote voltage sens e pin. connect this pin as close as possible to the battery pack positive connection. if the vsen pin is floating, its vo ltage drops to zero volt and the charger operates in the trickle mode. vbat (pin 10) vbat is the connection to the battery. typically a 10f tantalum capacitor is needed for stability when there is no battery attached. when a batt ery is attached, only a 0.1f ceramic capacitor is required. figure 15. status pin voltage vs current when the open-drain mosfet turns on typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r iref = r imin = 80k , v bat = 3.7v, unless otherwise noted. (continued) 0 4 8 12 16 20 24 28 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 status pin voltage (v) status pin current (ma) isl9203a
7 fn6430.0 february 14, 2007 typical applications block diagram v2p8 en gnd vbat iref vin 5v wall adapter battery pack vsen status time r iref c 1 c time 1k 1nf 10f 80k r 2 c 3 d 1 1f c 2 10f isl9203a 1 r 1 logic status i sen vin vbat 100000:1 current mirror counter + - + - v min + - + - v ch iref + - recharge minbat v rechrg ca va min_i i r i sen i min chrg status + - + - in pu t_o k v por trickle/fast references v2p8 temperature monitoring current references i t time osc gnd vin v ch v min v por v rechrg q main q sen r ir e f c 1 = i r /10 vsen + 100mv - en in pu t _o k vin esd diode r 1 figure 16. block diagram isl9203a
8 fn6430.0 february 14, 2007 charging flow chart figure 17. charging state diagram power up por v in >v por ? y n cv charge y n initialization reset counter trickle charge vsen>v min n y trickle charge cc charge vsen> =v ch ? y n constant current charge constant voltage charge vsen < v rechrg ? y n eoc en toggled ? y n i ch < i min ? reset status n eoc indication: set status high isl9203a
9 fn6430.0 february 14, 2007 theory of operation the isl9203a is an integrated charger for single-cell li-ion or li-polymer batteries. the isl9203a functions as a traditional linear charger when powered with a voltage- source adapter. when power ed with a current-limited adapter, the charger minimizes the thermal dissipation commonly seen in traditional linear chargers. as a linear charger, the isl9203a charges a battery in the popular constant current (cc) and constant voltage (cv) profile. the constant charge current i ref is programmable up to 1.5a with an external resistor. the charge voltage v ch has 1% accuracy over the entire recommended operating condition range. the charger always preconditions the battery with 10% of the programmed current at the beginning of a charge cycle, until the batte ry voltage is verified to be above the minimum fast charge voltage, v min . this low- current preconditioning charge mode is named trickle mode. the verification takes 15 cycles of an internal oscillator whose period is programmable with the timing capacitor. a thermal-foldback feature removes the thermal concern typically seen in linear chargers. the charger reduces the charge current automatically as the ic internal temperature rises above +100c to prevent further temperature rise. the thermal-foldback feature guarantees safe operation when the printed circuit board (pcb) is space limited for thermal dissipation. two indication pins are available from the charger to indicate the charge status. the v2p8 outputs a 2.8v dc voltage when the input voltage is above the power-on reset (por) level and can be used as a power-present indication. this pin is capable of sourcing a 2ma current, so it can also be used to bias external circuits. the status pin is an open- drain logic output that goes low at the beginning of a charge cycle and stays low unt il the end-of-charge (eoc) condition is qualified. the eoc condition is met when the battery voltage rises above a recharge threshold and the charge current falls below an eoc current threshold. once the eoc condition is qualified, the status output goes high and is latched. the latc h is released at the beginning of a re-charge cycle, when the en is toggled, or after the chip is power cycled. if the isl9203a has not been power cycled and has not had the en pin toggled, but the vsen voltage drops below the recharge level, then the devic e re-enters the charge mode. in this condition, the charge r indicates a re-charge cycle by bringing the status pin low. when the wall adapter is not present, the isl9203a draws less than 1 a of current from the battery. figure 18 shows the typical charge curves in a traditional linear charger powered with a constant-voltage adapter. from the top to bottom, the curves represent the constant input voltage, the battery voltage, the charge current and the power dissipation in the charger. the power dissipation p ch is given by the following equation: (eq. 1) where i charge is the charge current. the maximum power dissipation occurs during the beginning of the cc mode. the maximum power the ic is capable of dissipating is dependent on the thermal impedanc e of the printed-circuit board (pcb). figure 18 shows, with dotted lines, two cases that the charge currents are limited by the maximum power dissipation capability due to the thermal foldback. when using a current-limited adapter, the thermal situation in the isl9203a is totally differen t. figure 19 shows the typical charge curves when a current- limited adapter is employed. the operation requires the i ref to be programmed higher than the limited current i lim of the adapter, as shown in figure 19. the key difference of the charger operating under such conditions occurs during the cc mode. p ch v in v bat ? () i charge ? = figure 18. typical charge curves using a constant-voltage adapter v ch v min v in i ref i ref /10 p 1 p 2 p 3 trickle mode constant current mode constant voltage mode inhibit input voltage battery voltage charge current power dissipation isl9203a
10 fn6430.0 february 14, 2007 the block diagram, figure 16, aids in understanding the operation. the current loop consists of the current amplifier ca and the sense mosfet q sen . the current reference i r is programmed by the iref pi n. the current amplifier ca regulates the gate of the sense mosfet q sen so that the sensed current i sen matches the reference current i r . the main mosfet q main and the sense mosfet q sen form a current mirror with a ratio of 100,000:1, that is, the output charge current is 100,000 times i r . in the cc mode, the current loop tries to increase the charge current by enhancing the sense mosfet q sen , so that the sensed current matches the reference current. on the other hand, the adapter current is limi ted, the actual output current will never meet what is required by the current reference. as a result, the current error amplifier ca keeps enhancing the q sen as well as the main mosfet q main , until they are fully turned on. therefore, the main mosfet becomes a power switch instead of a linear regulation device. the power dissipation in the cc mode becomes: where r ds(on) is the resistance when the main mosfet is fully turned on. this power is typically much less than the peak power in the traditional linear mode. the worst power dissipation when using a current-limited adapter typically occurs at t he beginning of the cv mode, as shown in figure 19. the equation 1 applies during the cv mode. when using a very small pcb whose thermal impedance is relatively large, it is possible that the internal temperature can still reach the thermal foldback threshold. in that case, the ic is thermally protected by lowering the charge current, as shown by the dotted lines in the charge current and power curves. appr opriate design of the adapter can further reduce the peak power dissipation of the isl9203a. see the application information section of the isl6292 data sheet (www.intersil.com) for more information. figure 20 illustrates the typical signal waveforms for the linear charger from the power-up to a recharge cycle. more detailed applications information is given below. applications information power on reset (por) the isl9203a resets itself as the input voltage rises above the por rising threshold. the v2p8-pin outputs a 2.8v voltage, the internal oscillator starts to oscillate, the internal timer is reset, and the charger begins to charge the battery. the status pin indicates a low logic signal. figure 20 illustrates the start up of the charger between t 0 to t 2 . the isl9203a has a typical rising por threshold of 3.4v and a falling por threshold of 2.4v. the 2.4v falling threshold guarantees charger operation with a current- limited adapter to minimize the thermal dissipation. charge cycle a charge cycle consists of th ree charge modes: trickle mode, constant current (cc) mode, and constant voltage (cv) mode. the charge cycle always starts with the trickle mode until the battery voltage stays above v min (2.3v typical) for 15 consecutive cycles of the inte rnal oscillator. if the battery voltage drops below v min during the 15 cycles, the 15-cycle counter is reset and the charger stays in the trickle mode. the charger moves to the cc mode after verifying the battery voltage is above v min . when the battery-pack terminal voltage rises to the final charge voltage v ch , the cv mode begins. the terminal voltage is regulated at the constant v ch in the cv mode and the charge current declines. after the charge current drops below i min (1/10 of i ref , see section ??end-of-charge (eoc) current? on page 11 fo r more detail) the isl9203a indicates the end-of-charge with the status pin. the charging operation does not terminate. signals in a charge cycle are illustrated in figure 20 between points t 2 to t 5 . the end of charge indicator (status) will not be set if the charging current is below i min within the first 16 cycles after v bat exceeds the v rechrg voltage. if the charge current is still below i min after these 16 cycles, status goes high to indicate end of charge. the following events init iate a new charge cycle: ? por, ? the battery voltage drops below a recharge threshold, ? or, the en pin is toggl ed from gnd to floating. further description of these events are given later in this data sheet. figure 19. typical charge curves using a current limited adapter v ch v min v in i ref i ref /10 p 1 p 2 i lim trickle mode constant current mode constant voltage mode eoc input voltage battery voltage charge current power dissipation p ch r ds on () i charge 2 ? = (eq. 2) isl9203a
11 fn6430.0 february 14, 2007 recharge after a charge cycle completes, the charger continues to regulate the output at the constant voltage; but the status pin indicates that the charging is completed. the status pin stays high until the battery voltage drops to below the recharge threshold, v rechrg (see electrical specifications). then the status pin goes low and a new charge cycle starts at point t 6 . the charge cycle ends at point t 7 with the status pin again going high, as shown in figure 20. internal oscillator the internal oscillator establishes a timing reference. the oscillation period is programm able with an external timing capacitor, c time , as shown in typical applications. the oscillator charges the timing capacitor to 1.5v and then discharges it to 0.5v in one period, both with 10 a current. the period t osc is: (eq. 3) a 1nf capacitor results in a 0.2ms oscillation period.the accuracy of the period is mainly dependent on the accuracy of the capacitance and the internal current source. charge current programming the charge current in the cc mode is programmed by the iref pin. the voltage of iref is regulated to a 0.8v reference voltage. the charging current during the constant current mode is 100,000 times that of the current in the r iref resistor. hence, the charge current is, (eq. 4) table 1 shows the charge current vs. selected r iref values. the typical trickle charge curr ent is 10% of the programmed constant charge current. table 2 shows the trickle charge current tolerance guidance at given r iref values, when the battery voltage is between 0v to 2.5v. note: the values in table 2 and tabl e 1 are not tested and are only for guidance in selecting resistor values for mass production tests or in customer?s products. end-of-charge (eoc) current the eoc current i min sets the level at which the charger starts to indicate the end of the charge with the status pin, as shown in figure 20. the charger actually does not terminate charging. in the isl9203a, the eoc current is internally set to 1/10 of the cc charge current, that is: (eq. 5) at the eoc, the status signal rises to high and is latched. the latch is not reset until a recharge cycle or a new charge cycle starts. the tolerance guidance for the eoc current at selected r iref values are given in table 3. note: the values in table 3 are not tested and are only for guidance in selecting resistor values for ma ss production tests or in customer?s products. figure 20. operation waveforms vin v2p8 status vbat i charge at least 15 cycles por threshold 2.8v v min v rechrg t 0 t 1 t 2 t 3 t 4 t 5 charge cycle i min t 6 t 7 charge cycle t osc 0.2 10 6 c time ? ? = onds sec () i ref 0.8v r iref ----------------- 10 5 a () = table 1. charge current vs r iref values r iref (k ) charge current (ma) min typ max 267 ~ 160 17% lower than typ value = i ref in eq. 5 17% higher than typ value 160 450 500 550 100 720 800 880 88.9 810 900 990 80 900 1000 1100 table 2. trickle charge current vs r iref values r iref (k ) trickle charge current (ma) min typ max 267 15 30 60 160 30 50 80 100 40 80 120 88.9 45 90 135 80 70 100 150 table 3. eoc current vs r iref values r iref (k ) eoc current (ma) min typ max 267 15 30 60 160 30 50 80 100 40 80 120 88.9 45 90 135 80 70 100 150 i min 1 10 ------ i ref ? = isl9203a
12 fn6430.0 february 14, 2007 charge current thermal foldback over-heating is always a concern in a linear charger. the maximum power dissipation usually occurs at the beginning of a charge cycle when the batter y voltage is at its minimum but the charge current is at it s maximum. the charge current thermal foldback function in the isl9203a frees users from the over-heating concern. figure 21 shows the current signals at the summing node of the current error amplifier ca in the block diagram. i r is the reference. i t is the current from t he temperature monitoring block. the i t has no impact on the charge current until the internal temperature reaches approximately +100c; then i t rises at a rate of 1a/c. when i t rises, the current control loop forces the sensed current i sen to reduce at the same rate. as a mirrored current, the charge current is 100,000 times that of the sensed current and reduces at a rate of 100ma/c. for a charger with t he constant charge current set at 1a, the charge current is reduced to zero when the internal temperature rises to +110c. the actual charge current settles between +100c to +110c. usually the charge current should not drop below i min because of the thermal foldback. for some extreme cases if that does happen, the charger does not indicate end-of- charge unless the battery voltage is already above the recharge threshold. 2.8v bias voltage the isl9203a provides a 2.8v voltage for biasing the internal control and logic circuit. this voltage is also available for external circuits such as the ntc thermistor circuit. the maximum allowed external load is 2ma. indications the isl9203a has two indications: the input presence and the charge status. the input presence is indicated by the v2p8 pin and the charge status is indicated by the status pin. figure 22 shows the v2p8 pin voltage vs. the input voltage. status pull-up resistor the status pin is an open-drain output that need an external pull-up resistor. it is recommended that this be pulled up to the input voltage or the 2.8v from the v2p8 pin. if the ststus pin has to be pulled up to other voltages, the user needs to examine carefully whether or not the esd diodes will form a leakage current path to the battery when the input power is removed. if the leakage path does exist, an external transistor is required to break the path. figure 23 shows the implementation. if the status pin is directly pulled up to the vcc voltage (not shown in figure 23), a current will flow from the vcc to the status pin, then through the esd diode to the vin pin. any leakage on the vin pin, caused by an external or internal current path, will result in a current path fr om vcc to ground. the n-channel mosfet q 1 buffers the status pin. the gate of q 1 is connected to vin or the v2p8 pin. when the status pin outputs a logic low signal, q 1 is turned on and its drain outputs a low signal as well. when status is high impedance, r 1 pulls the q 1 drain to high. when the input power is removed, the q 1 gate voltage is also removed, thus the q 1 drain stays high. shutdown the isl9203a can be shutdown by pulling the en pin to ground. when shut down, the charger draws typically less than 30a current from the i nput power and t he 2.8v output at the v2p8 pin is also turned off. the en pin needs be driven with an open-drain or open-collector logic output, so that the en pin is floating when the charger is enabled. if the en pin is driven by an external source, the por threshold voltage will be affected. figure 21. current signals at the amplifier ca inpu t temperature +100c i r i t i sen figure 22. the v2p8 pin ou tput vs the input voltage at the vin pin. vertical: 1v/div, horizontal: 100ms/div 3.4v 2.4v 2.8v v in v2p8 isl9203a
13 fn6430.0 february 14, 2007 input and output capacitor selection due to the inductance of the power leads of the wall adapter or usb source, the input capacitor type must be properly selected to prevent high voltage transient during a hot-plug event. a tantalum capacitor is a good choice for its high esr, providing damping to the voltage transient. multi-layer ceramic capacitors, however, have a very low esr and hence when chosen as input capacitor, a 1 series resistor must be used, as shown in the typical applications section, to provide adequate damping. the output capacitor can be any ceramic type with the value higher than 0.1f. however, if there is a chance the charger will be used as an ldo linear regulator, a 10f tantalum capacitor is recommended. note that the charger always steps through the 15-cycle v min verification time before the charge current rises to the constant charge current, as discussed earlier. hence, when using as an ldo, the system should make sure not to load the charger heavily until the 15-cycle verifi cation is completed. working with current-limited adapter the isl9203a can work with a current-limited adapter to significantly reduce the thermal dissipation during charging. refer to the isl6292 data shee t, which can be found at http://www.intersil.com, for more details. board layout recommendations the isl9203a internal thermal foldback function limits the charge current when the internal temperature reaches approximately +100c. in order to maximize the current capability, it is very important that the exposed pad under the package is properly soldered to the board and is connected to other layers through thermal vias. more thermal vias and more copper attached to the exposed pad usually result in better thermal performance. on the other hand, the number of vias is limited by the size of the pad. the 3x3 dfn package allows 8 vias be placed in two rows. since the pins on the 3x3 dfn package are on only two sides, as much top layer copper as possible should be connected to the exposed pad to minimize the thermal impedance. refer to the isl6292 evaluation boards for layout examples. figure 23. pull-up circuit to avoid battery leakage current in the esd diodes status vin esd diode control en vcc gnd vin or v2p8 r 1 note: r lkg is approximately 240k when en is floating and r lkg q 1 is approximately 140k when the en is grounded. isl9203a
14 all intersil u.s. products are manufactured, asse mbled and tested utilizing iso9000 quality systems. intersil corporation?s quality certifications ca n be viewed at www.intersil.com/design/quality intersil products are sold by description only. intersil corpor ation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnishe d by intersil is believed to be accurate and reliable. however, no responsibility is assumed by intersil or its subsidiaries for its use; nor for any infringements of paten ts or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiari es. for information regarding intersil corporation and its products, see www.intersil.com fn6430.0 february 14, 2007 isl9203a dual flat no-lead plastic package (dfn) d e a b 0.10 mc e 0.415 c section "c-c" nx (b) (a1) 2x c 0.15 0.15 2x b nx l ref. (nd-1)xe 5 a c (datum b) d2 d2/2 e2 e2/2 top view 7 bottom view 5 6 index area 8 ab nx k 6 index area (datum a) 12 n-1 n nx b 8 nx b nx l 0.200 c a seating plane 0.08 c a3 side view 0.10 c l10.3x3 10 lead dual flat no-lead plastic package symbol millimeters notes min nominal max a 0.80 0.90 1.00 - a1 - - 0.05 - a3 0.20 ref - b 0.18 0.23 0.28 5,8 d 3.00 bsc - d2 1.95 2.00 2.05 7,8 e 3.00 bsc - e2 1.55 1.60 1.65 7,8 e 0.50 bsc - k0.25 - - - l0.30 0.35 0.40 8 n102 nd 5 3 rev. 3 6/04 notes: 1. dimensioning and tolerancing conform to asme y14.5-1994. 2. n is the number of terminals. 3. nd refers to the number of terminals on d. 4. all dimensions are in millimeters. angles are in degrees. 5. dimension b applies to the meta llized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 6. the configuration of the pin #1 identifier is optional, but must be located within the zone indicated. the pin #1 identifier may be either a mold or mark feature. 7. dimensions d2 and e2 are fo r the exposed pads which provide improved electrical and thermal performance. 8. nominal dimensions are prov ided to assist with pcb land pattern design efforts, see intersil technical brief tb389. for odd terminal/side c l e terminal tip l c c

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