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aat3663 1a linear li-ion battery charger for single and dual cell applications typical application vin r term adpp# on/off en term gnd bat stat2 r set iset in stat1 ct 10f batt- battery pack batt+ - temp c t ts bats aat3663 3663.2007.10.1.0 1 batterymanager ? general description the aat3663 batterymanager ? is a member of analogictechs total power management ic ? family. this device is an integrated single/dual cell lithium-ion (li-ion) / polymer battery charger ic designed to operate from usb ports or an ac adapter inputs up to an input voltage of 13.2v. aat3663 precisely regulates battery charge volt- age and current for 4.2v and 8.4v li-ion battery cells. the battery charging current is user pro- grammed up to 1a by an external resistor. battery charge state is continuously monitored for fault conditions. a digital thermal loop control maintains the maximum possible battery charging current for the optimum set of input to output power dissipation and ambient temperature conditions. in the event of an over-current, over-voltage, short- circuit, or over-temperature fault condition, the device will automatically shut down, thus protecting the charger and the battery under charge. two status monitor output pins are provided to indi- cate the battery charge status by directly driving external leds. additionally, an open-drain power- source detection output (adpp#) is provided to report presence of an input power supply the aat3663 is available in a thermally enhanced, space-saving, 14-pin 3x3 mm tdfn package and is specified for operation over the -40c to +85c temperature range. features ? 4.0v ~ 13.2v input voltage range ? compatible with usb or ac adapter sources ? programmable fast charge current from 100ma to 1a ? programmable charge termination current ? digital thermal loop charge reduction ? less than 0.4a battery leakage current ? programming charge timer ? battery temperature sensing ? battery temp sense open circuit detection ? automatic recharge sequencing ? automatic trickle charge for battery pre-conditioning ? automatic charge termination shutdown/sleep mode ? less than 1a shutdown current ? over-voltage and over-current protection ? power on reset and soft start ? 3x3mm 14-pin tdfn package applications ? bluetooth? headset ? cell phones ? digital still cameras ? mp3 players ? personal data assistants (pdas) ? other li-ion battery powered devices
pin description pin configuration tdfn33-14 (top view) en iset gnd 1 ts bats bat n/c adpp # stat2 stat1 in in ct 2 3 4 5 6 7 14 term 13 12 11 10 9 8 pin # symbol type function 1 en i enable pin, active high with internal pull-down. if not used, pull high to the in pin to continuously enable the charger ic when input power is applied. 2 ct i charge timer programming pin. a 0.1f ceramic capacitor should be connected between this pin and gnd. connect directly to gnd to disable the timer function. 3 iset i charge current programming pin. connect a resistor between this pin and gnd to program the constant fast charge current. 4 gnd i/o ic ground connection. connect this pin to power ground. 5 ts i/o battery temperature sense input. connect the li-ion battery pack ntc resistor termi- nal to this pin. 6 bats i battery voltage sense pin. connect this pin directly to the positive battery terminal. if this function is not used, connect to the bat pin directly. 7 bat o battery charge output pin. connect to the positive battery terminal. 8, 9 in i power supply input pin. connect the input usb port or adapter power source to this pin 10 stat1 o charge status pin, open-drain output. connect the stat1 led with a series ballast resistor between in and this pin. 11 stat2 o charge status pin, open-drain output. connect the stat2 led with a series ballast resistor between in and this pin. 12 adpp# o input supply power-good status pin, open-drain output. connect the adpp# status led with a series ballast resistor between in and this pin. 13 term i charge termination current programming input pin. connect a resistor between this pin and gnd to program the charge termination current. when term is open, the termination current is 10% (default sertting) of the set maximum charge current. 14 n/c no connection. aat3663 1a linear li-ion battery charger for single and dual cell applications 2 3663.2007.10.1.0
absolute maximum ratings 1 thermal information 2 aat3663 feature options product number of battery cells battery temperature sense aat3663-4.2-1 single for use with any ntc thermistor aat3663-4.2-2 single for use with 10k ntc thermistor aat3663-8.4-1 dual for use with any ntc thermistor aat3663-8.4-2 dual for use with 10k ntc thermistor symbol description value units ja maximum thermal resistance (tdfn3x3) 50 c/w p d maximum power dissipation 2 w symbol description value units v in in continuous voltage -0.3 to 14 v v n stat1, stat2, adpp#, en, bat, bats -0.3 to v in + 0.3 v v n ts, ct, term, iset -0.3 to 5.5 v t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads) 300 c aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 3 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at c ondi- tions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any one time. 2. mounted on a fr4 board.
electrical characteristics v in = 5v, t a = -25 to +85 c; unless otherwise noted, typical values are at t a = 25 c symbol description conditions min typ max units operation v in input voltage range 4.0 13.2 v v uvlo under voltage lockout threshold rising edge 3 4 v uvlo hysteresis 150 mv v adpp_th adapter present indicator threshold v in > v uvlo 50 100 mv voltage, v in C v bat i op operating current charge current = 100ma 0.35 1 ma i shutdown shutdown current v bat = 4.25v, en = gnd 0.4 1 a i leakage leakage current from bat pin v bat = 4v, in = open 0.4 2 a en leakage en pin leakage v en = 5v 0.6 a voltage regulation v bat_eoc end of charge voltage regulation aat3663-4.2 4.158 4.2 4.242 v aat3663-8.4 8.316 8.4 8.484 v bat_eoc / end of charge voltage accuracy 0.5 % v bat _ eoc v min preconditioning voltage threshold aat3663-4.2 2.5 2.6 2.7 v aat3663-8.4 5.0 5.2 5.4 aat3663-4.2 v bat_eoc v rch battery recharge voltage threshold - 0.1 v aat3663-8.4 v bat_eoc - 0.2 current regulation i cc_range charge current programmable range 100 1000 ma r iset = 1.74k (for 1a), 900 1000 1100 i ch_cc constant-current mode v bat = 3.6v ma charge current r iset = 17.8k (for 0.1a), 80 100 120 v bat = 3.6v v iset iset pin voltage 2 v k iset charge current set factor: constant current mode, 900 i ch _ cc /i set v bat = 3.6v v term term pin voltage r term = 40k 0.6 v i ch_trk trickle-charge current 5 10 15 % i ch _ cc term pin open 5 10 15 % i ch _ cc i ch_term charge termination current threshold r term = 13.3 k , 81012% i ch _ cc i ch_cc 800ma charging devices r ds(on) charging transistor on resistance v in = 5v 330 500 m logic control / protection v en input high threshold 1.6 v input low threshold 0.4 v s tat output low voltage stat pin sinks 4ma 0.4 v i s tat stat pin current sink capability 8 ma aat3663 1a linear li-ion battery charger for single and dual cell applications 4 3663.2007.10.1.0
electrical characteristics v in = 5v, t a = -25 to +85 c; unless otherwise noted, typical values are at t a = 25 c symbol description conditions min typ max units logic control / protection v addp# output low voltage adpp# pin sinks 4ma 0.4 v i adpp# addp# current sink capability 8 ma v ovp over-voltage protection threshold aat3663-4.2 4.4 v aat3663-8.4 8.8 v ocp over-current protection threshold 105 %v cs tk trickle charging time-out c t = 100nf, v in = 5v t c /8 hour tc trickle and constant current c t = 100nf, v in = 5v 3 hour mode time-out tv constant voltage mode time-out c t = 100nf, v in = 5v 3 hour i ts current source from ts pin aat3663-2 only 71 75 79 a t s1 ts hot temperature fault threshold, aat3663-2 only 316 331 346 mv hysteresis, aat3663-2 only 25 t s2 ts cold temperature fault threshold, aat3663-2 only 2.30 2.39 2.48 mv hysteresis, aat3663-2 only 25 v ts1 high temperature threshold threshold, aat3663-1 only 29.1 30 30.9 %v in hysteresis, aat3663-1 only 2 v ts2 low temperature threshold threshold, aat3663-1 only 58.2 60 61.8 %v in hysteresis, aat3663-1 only 2 t loop_in digital thermal loop entering 115 oc threshold t loop_out digital thermal loop exiting 85 oc threshold t reg digital thermal loop regulation 100 oc t shdn over-temperature shutdown threshold 140 oc hysteresis 15 aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 5
typical characteristics recharge threshold voltage vs. input voltage input voltage (v) battery voltage (v) 4.080 4.085 4.090 4.095 4.100 4.105 4.110 4.115 4.120 4 5 6 7 8 9 10 11 12 13 14 recharge voltage vs. temperature (v in = 5v; r set = 8.87k ) temperature (oc) battery voltage (v) 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 -40 -15 10 35 60 8 5 end of charge voltage accuracy vs. input voltage (v bat_eoc = 4.2v) input voltage (v) end of charge voltage accuracy (%) -0.100 -0.075 -0.050 -0.025 0.000 0.025 0.050 0.075 0.100 4 5 6 7 8 9 10 11 12 13 14 end of charge voltage vs. temperature temperature (c) battery voltage (v) 4.180 4.185 4.190 4.195 4.200 4.205 4.210 4.215 4.220 -40 -15 10 35 60 85 operating current vs i set resistor r set (k ) operating current (a) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 1 10 100 constant current mode preconditioning mode constant charging current vs. set resistor values r set (k ) constant charge current (ma) 1 10 100 1000 10000 1 10 100 aat3663 1a linear li-ion battery charger for single and dual cell applications 6 3663.2007.10.1.0
typical characteristics preconditioning charge current vs. input voltage input voltage (v) i ch_trk (ma) 0 20 40 60 80 100 120 4 5 6 7 8 9 10 11 12 13 14 r set = 1.78k r set = 2.21k r set = 3.57k r set = 8.87k temperature sense output current vs. temperature temperature (c) i ts (a) 70 71 72 73 74 75 76 77 78 79 80 -40 -15 10 35 60 85 preconditioning threshold voltage vs. input voltag e input voltage (v) battery voltage (v) 2.50 2.52 2.54 2.56 2.58 2.60 2.62 2.64 2.66 2.68 2.70 4 5 6 7 8 9 10 1112 1314 preconditioning threshold voltage vs. temperature temperature (c) battery voltage (v) 2.50 2.52 2.54 2.56 2.58 2.60 2.62 2.64 2.66 2.68 2.70 -40 -15 10 35 60 85 constant charging current vs. v bat (r set = 8.87k ) v bat (v) charging current (ma) 0 30 60 90 120 150 180 210 240 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4. 3 v in = 13.2v v in = 12v v in = 7.5v v in = 9.5v v in = 5v constant charging current vs. battery voltage battery voltage (v) i ch (ma) 0 200 400 600 800 1000 1200 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 1.78k 2.21k 3.57k 8.87k aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 7
typical characteristics charging transistor on resistance vs. input voltage input voltage (v) r ds(on) (m ) 0 100 200 300 400 500 600 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 7.2 7.6 8.0 8. 4 85c 25c -40c termination current to constant current ratio (%) vs. termination resistance r term (k ) i ch_term /i ch_cc (%) 0 5 10 15 20 25 30 35 40 45 50 0 102030405060 input high threshold vs. input voltage input voltage (v) v en(h) (v) 0.40 0.60 0.80 1.00 1.20 1.40 1.60 4 5 6 7 8 9 10 11 12 13 1 4 -40c 25c 85c input low threshold vs. input voltage input voltage (v) v en(l) (v) 0.40 0.60 0.80 1.00 1.20 1.40 1.60 4 5 6 7 8 9 10 11 12 13 1 4 -40c 25c 85c constant charge current vs. input voltage input voltage (v) charge current (ma) 160 170 180 190 200 210 220 230 240 4 5 6 7 8 101112131 4 v bat = 4.1v v bat = 3.9v v bat = 3.5v v bat = 3v shutdown current vs. input voltage input voltage (v) shutdown current (a) 0.00 0.30 0.60 0.90 1.20 1.50 1.80 2.10 2.40 4 5 6 7 8 9 10 11 12 13 1 4 85c 25c -40c aat3663 1a linear li-ion battery charger for single and dual cell applications 8 3663.2007.10.1.0
typical characteristics ct pin capacitance vs. counter timeout timeout (h) capacitance (f) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 0.5 1 1.5 2 2.5 3 4 4.5 5 3.5 preconditioning timeout preconditioning + constant current timeout or constant voltage timeout aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 9
functional block diagram charge control current compare reverse blocking cv/ precharge constant current in bat iset uvlo over-temp protect power detection stat 1 gnd en thermal loop a dpp# charge status bats ct ts stat 2 watchdog timer term 75a aat3663-2 only window comparator aat3663 1a linear li-ion battery charger for single and dual cell applications 10 3663.2007.10.1.0 functional description the aat3663 is a high performance battery charger designed to charge single/dual cell lithium-ion or lithium-polymer batteries with up to 1000ma of current from an external power source. it is a highly integrated stand-alone charging solution, with the least external components required for complete functionality. the aat3663 precisely regulates end of charge bat- tery voltage and current for single cell 4.2v and dual cell 8.4v lithium-ion/polymer battery with a program- mable constant current range from 100ma to 1a for fast charging applications. the system has a default charge termination current set to 10 percent of the pro- grammed fast charge constant. the charge termina- tion current may also be user programmed by an external resistor. during battery charging, the device temperature will rise. in some cases with adapter (adp) charging, the power dissipation in the charge regulation pass device may cause the junction temperature to rise and approach the internal thermal shutdown threshold. excessive power dissipation is caused by the high input adapter voltage versus the low output battery cell voltage difference at a given constant charge current. in the event of an internal over-temperature condition caused by excessive ambient operating temperature or excessive power dissipation conditions, the aat3663 enables a digitally controlled thermal loop system that will reduce the charging current to prevent thermal shutdown. the digital thermal loop will main- tain the maximum possible battery charging current for a given set of input to output power dissipation and ambient temperature conditions. the digital thermal loop control is dynamic in the sense that it will continue to adjust the battery charging cur- rent as operating conditions change. the digital ther- mal loop will reset and resume normal operation when the power dissipation or over-temperature conditions are removed. in the event of an over-voltage, over-current or over- temperature false condition beyond the limits of the digital thermal loop system, the device will automati- cally shut down, thus protecting the charging device, control system, and the battery under charge. aat3663 provides two status monitor pins, stat1 and stat2. these pins are open drain mosfet switches intended to directly drive external leds to indicate the battery charging state. a third status pin is prided to
indicate the presence of power on the input supply pin. this open drain mosfet switch may be used to either power a display led or to alert a system microcon- troller for the presence on input power. battery charging operation figure 1 illustrates the entire battery charging profile and operation, which consists of three phases: 1. preconditioning (trickle) charge 2. constant current charge 3. constant voltage charge when power is initially applied or when a battery pack is connected to the bat pin, battery charging com- mences after the aat3663 checks several conditions in order to maintain a safe charging environment. the input supply must be above the minimum operating voltage (uvlo) and the enable pin must be high (inter- nally pulled down). when the battery is connected to the bat pin the aat3663 checks the condition of the battery and determines which charging mode to apply. battery preconditioning if the battery voltage is below v min , the aat3663 begins battery trickle charging by charging at 10% of the pro- grammed constant-current. for example, if the pro- grammed current is 500ma, then the trickle charge cur- rent is 50ma. trickle charging is a recommended safe- ty precaution for a deeply discharged cell and maxi- mizes the charge cycle life of the battery. in addition, charger ic power dissipation for the internal series pass mosfet is minimized when the input-output voltage differential is at its highest. this in turn allows the charging operation to commence over wider thermal and input to output voltage differential conditions. constant current charging trickle charging continues until the battery voltage reaches the v min threshold. at this point, the aat3663 begins constant-current fast charging. the current level for this mode is programmed using a single resis- tor from the iset pin to ground. programmed current can be set at a minimum 100ma up to a maximum 1a. constant voltage charging constant current charging continues until such time that the battery voltage reaches the voltage regulation point v bat_reg . when the battery voltage reaches v bat_reg , the aat3663 will transition to the constant- voltage mode. the regulation voltage is factory pro- grammed to a nominal 4.2v for the aat3663-4.2 option and to 8.4v for the aat3663-8.4 option. under default conditions with the term pin not connected (open circuit), constant voltage charging will continue until the charge current has reduced to 10% of the pro- grammed current. placing a resistor between the term pin and ground allows the user to program a desired termination current. after the charge cycle is complete, the aat3663 turns off the series pass device and automatically goes into a power saving sleep mode. during this time the series pass device will block current in both directions there- fore preventing the battery discharging through the ic. the aat3663 will remain in sleep mode, until either the battery terminal voltage drops below the v rch thresh- old, the charger en pin is recycled or the charging power source is reconnected. in all cases the aat3663 will monitor all battery parameters and resume charging in the appropriate mode. aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 11 figure 1: current and voltage profile during charging phases. constant current charge phase constant voltage charge phase preconditioning trickle charge phase charge complete voltage constant current mode voltage threshold regulated current trickle charge and termination threshold i = cc / 10 i = max cc
system operation flow chart v ch >v bat v min >v bat shut down mode shut down mode i bat > i min no no charge completed charge completed recharge rch v yes set expire yes no device temp. monitor t j >110 c yes adp voltage s adp > v adpp no preconditioning test v min >v bat current phase test v in >v bat_eoc voltage phase test i bat >i term shut down mode shut down mode no no charge completed charge completed test v rch > bat yes set expire yes no device temp . monitor t j >115 c yes fault no yes no power select power input voltage v in >v uvlo power select fault condition monitoring ov, ot, v ts1 i term shut down mode shut down mode shut down mode fault stat1=off stat2=off yes aat3663 1a linear li-ion battery charger for single and dual cell applications 12 3663.2007.10.1.0
aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 13 application information adapter or usb power input constant current charge levels up to 1a may be programmed by the user when powered from a suf- ficient input power source. the aat3663 will oper- ate over an input voltage range from 4.0v to 13.2v. the low input voltage capability of the aat3663 permits charging single cell li-ion/poly batteries from usb ports and lower voltage input power sources. the high 13.2v input rating of this device allows for the use of a wide range of input power sources for both single and dual cell li-ion/poly applications. adapter input charge inhibit and resume the aat3663 has an under-voltage lockout (uvlo) and power on reset feature so that if the input sup- ply to the in pin drops below the uvlo threshold, the charger will suspend charging and shut down. when power is reapplied to the in pin or the uvlo condition recovers, the system charge control will assess the state of charge on the battery cell and will automatically resume charging in the appropriate mode for the condition of the battery. battery connection and battery voltage sensing battery connection a single or dual cell li-ion/polymer battery should be connected between the bat pin and ground. battery voltage sensing the bats pin is provided to employ an accurate voltage sensing capability to measure the positive terminal voltage at the battery cell being charged. this function reduces measured battery cell volt- age error between the battery terminal and the charge control ic. the aat3663 charge control cir- cuit will base charging mode states upon the volt- age sensed at the bats pin. the bats pin must be connected to the battery terminal for correct operation. if the battery voltage sense function is not needed, the bats pin should be terminated directly to the bat pin. if there is concern of the battery sense function inadvertently becoming an open circuit, the bats pin may be terminated to the bat pin using a 10k resistor. under normal oper- ation, the connection to the battery terminal will be close to 0 ; if the bats connection becomes an open circuit, the 10k resistor will provide feed- back to the bats pin from the bat connection with a voltage sensing accuracy loss of 1mv or less. enable (en) en is a logic input (active high) to enable the charger, this function is internally pulled down to ground. when the device is initially enabled or if the en pin is cycled low and then re-enabled, the charge control circuit will automatically reset and resume charging functions with the appropriate charging mode based on the battery charge state and measured battery voltage on the bats pin. programming charge current the constant current mode charge level is user pro- grammed with a set resistor (r set ) connected between the iset pin and ground. the accuracy of the constant charge current, as well as the precon- ditioning trickle charge current, is dominated by the tolerance of the set resistor used. for this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. the constant charge cur- rent levels from 100ma to 1a may be set by select- ing the appropriate resistor value from table 1. table 1: r set values. constant charging set resistor current (ma) value (k) 100 17.8 200 8.87 300 5.9 400 4.42 500 3.57 600 2.94 700 2.55 800 2.21 900 1.96 1000 1.78
figure 2: constant charging current vs. r set resistor values. if the desired charge current level is not listed in table 1, the r set resistor value can be found in figure 2 and calculated by the following equation: where: k = k i_set = 900 v iset = 2v i cc = fast charge constant current programmable charge termination current the aat3663 is designed with a default charge ter- mination current set to 10 percent of the pro- grammed fast charge constant current level. the charge termination current (i ch_term ) may also be user programmed to a level other than 10% of the set fast charge current by connecting a set resistor (r term ) between the term pin and ground. when the charge current under the constant volt- age charging mode drops to the charge termination threshold the device halts charging and goes into a sleep mode. the charger will remain in the sleep mode until the battery voltage as sensed by the bats pin decreases to a level below the battery recharge voltage threshold (v rch ). charge termi- nation current levels based on a percentage of the programmed fast charge current are shown in figure 3. figure 3: charge termination current (% value of the programmed fast charge current) vs. r term resistance. if the desired charge termination current set resistor (r term ) value is not shown in figure 3, the value may be determined by the following equation: where: i ch_term = charge termination current level i ch_cc = programmed fast charge constant current level r term = term resistor value battery charge status indication the aat3663 indicates the status of the battery under charge using three status led driver out- puts. these three leds can indicate simple func- tions such as input power present, no battery charge activity, battery charging, charge complete and charge fault. status indicator display system charging status may be displayed using one or two leds in conjunction with the stat1 and stat2 pins on the aat3663. these two pins are simple open drain n-channel mosfet switches to connect the status led cathodes to ground. it is not necessary to use both display leds if a user simply wants to have a single led to show charg- ing or not charging. this can be accomplished i ch_term = i ch_cc 15a r term 2v r term (k ) i ch_term /i ch_cc (%) 0 5 10 15 20 25 30 35 40 45 50 0 102030405060 r set = k ?? ?? v iset i cc r set (k ) cc mode charge current (ma) 1 10 100 1000 10000 1 10 100 aat3663 1a linear li-ion battery charger for single and dual cell applications 14 3663.2007.10.1.0
aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 15 by just using the stat1 pin and a single led. using two leds and both stat pins simply gives the user more information for the various charging states. refer to table 2 for led display definitions. the led anodes should be connected to the charger power source input (in pin). table 2: led status indicator truth table. input power present indicator the addp# pin provides an additional open drain n-channel mosfet switch to indicate the pres- ence of power applied to the charger input (in pin). this function may either be used to control an addi- tion status led to give a visual indication when input power is applied. this open drain output may also be pulled high via a pull up resistor to provide an active low signal to a system microcontroller to indicate the presence of applied input power. status display led biasing the led should be biased with as little current as necessary to create reasonable illumination; there- fore, a ballast resistor should be placed between the led cathode and the stat pin. led current consumption will add to the overall thermal power budget for the device package, hence it is good to keep the led drive current to a minimum. 2ma should be sufficient to drive most low-cost green or red leds. it is not recommended to exceed 8ma for driving an individual status led. the required ballast resistor values can be esti- mated using the following formula: example: note: red led forward voltage (v f ) is typically 2.0v @ 2ma. digital thermal loop control due to the integrated nature of the linear charging control pass device for the adapter mode, a special thermal loop control system has been employed to maximize charging current under all operation con- ditions. the thermal management system meas- ures the internal circuit die temperature and reduces the fast charge current when the device exceeds a preset internal temperature control threshold. once the thermal loop control becomes active, the fast charge current is initially reduced by a factor of 0.28. the initial thermal loop current can be estimated by the following equation: i tloop = i ch_cc 0.28 the thermal loop control re-evaluates the circuit die temperature every 1.5 seconds and adjusts the fast charge current back up in small steps to the full fast charge current level or until an equilibrium current is discovered and maximized for the given ambient temperature condition. the thermal loop controls the system charge level; therefore, the aat3663 will always provide the highest level of constant current in the fast charge mode possible for any given ambient temperature condition. (5.0v - 2.0 v) r ballast = = 1.5k 2ma (v in - v f(led) ) r ballast = i led event description stat1 stat2 charge enabled without battery flash 1 flash 1 battery charging on off charging completed off on fault off off 1. flashing rate depends on output capacitance.
aat3663 1a linear li-ion battery charger for single and dual cell applications 16 3663.2007.10.1.0 protection circuitry programmable timer function the aat3663 contains a watchdog timing circuit to shut down charging functions in the event of a defective battery cell not accepting a charge over a preset period of time. typically, a 0.1f ceramic capacitor is connected between the ct pin and ground. when a 0.1f ceramic capacitor is used, the device will time out a shutdown condition if the trickle charge mode exceeds 25 minutes and a combined trickle charge plus constant current mode of 3 hours. when the device transitions to the constant voltage mode, the timing counter is reset and will time out after an additional 3 hours if the charge current does not drop to the charge ter- mination level. the aat3663 has a battery fault detector, which, when used in conjunction with a 0.1f capacitor on the ct pin, outputs a 1hz signal with 50% duty cycle at the stat1 pin in the event of a timeout while in the trickle charge mode. table 3: summary for a 0.1f ceramic capacitor used for the timing capacitor. the ct pin is driven by a constant current source and will provide a linear response to increases in the timing capacitor value. thus, if the timing capacitor were to be doubled from the nominal 0.1f value, the timeout periods would be doubled. if the programmable watchdog timer function is not needed, it can be disabled by terminating the ct pin to ground. the ct pin should not be left floating or unterminated, as this will cause errors in the internal timing control circuit. the constant current provided to charge the timing capacitor is very small, and this pin is susceptible to noise and changes in capacitance value. therefore, the timing capacitor should be physically located on the print- ed circuit board layout as close as possible to the ct pin. since the accuracy of the internal timer is dominated by the capacitance value, a 10% toler- ance or better ceramic capacitor is recommended. ceramic capacitor materials, such as x7r and x5r types, are a good choice for this application. over-voltage protection an over-voltage event is defined as a condition where the voltage on the bat pin exceeds the max- imum battery charge voltage and is set by the over- voltage protection threshold (v ovp ). if an over-volt- age condition occurs, the aat3663 charge control will shut down the device until the voltage on the bat pin drops below v ovp . the aat3663 will resume normal charging operation after the over- voltage condition is removed. during an over-volt- age event, the stat leds will report a system fault. over-temperature shutdown the aat3663 has a thermal protection control cir- cuit which will shut down charging functions once the internal die temperature exceeds the over-tem- perature shutdown threshold. once the internal die temperature falls below the hysteresis, normal operation will resume the previous charging state. battery temperature fault monitoring there are two aat3663 temperature sense options, the aat3663-1 and aat3663-2. the aat3663-1 option allows of the use of any ntc resistor. for ease of use, the aat3663-2 option is factory set to function with typical 10k ntc resistors and elimi- nates the need for a resistor divider pull up to the input power source. regardless of the aat3663 option selected, the internal system control checks battery temperature before starting the charge cycle and continues to monitor the battery temperature during all stages of the charging cycle. this is accomplished by moni- toring the voltage at the ts pin. in general, the sys- tem is intended for use with negative temperature coefficient thermistors (ntc) which are typically integrated into the battery package. the voltage on the ts pin resulting from the resistive load and applied current, should stay within a window bounded by the ts1 and ts2 specification thresh- olds. refer to the electrical characteristics table for the ts1 and ts2 limits for a selected aat3663 option. if the battery becomes too hot during charge cycle due to an internal fault or excessive charge current, the ntc thermistor will heat up and reduce in value. this in turn will pull the ts pin mode time trickle charge (tc) time out 25 minutes trickle charge (tc) + constant 3 hours current (cc) mode time out constant voltage (cv) mode time out 3 hours
voltage below than the ts1 threshold, and indicate a battery cell temperature fault. the charging process will then be suspended until the over-tem- perature condition is removed, at which time charging will resume. conversely, if the battery under charge is exposed to extreme cold ambient temperature condition, the ntc thermistor may increase in value and push the voltage on the ts pin above the ts2 threshold. in such a case, the charge cycle will be suspended and will not resume until the cold fault condition is removed. both ts1 and ts2 temperature fault conditions will be report by the stat1 and stat2 leds. aat3663-1 option the aat3663-1 option utilizes an internal battery temperature sensing system comprised of two com- parators which establish a voltage window for safe operation. the thresholds for the ts operating win- dow are bounded by the ts1 and ts2 specifica- tions. referring to the electrical characteristics table in this datasheet, the ts1 threshold = 0.30 v in and the ts2 threshold = 0.6 v in . refer to figure 4 for external resistor and ntc thermistor connections. if the use of the battery temperature sense function is not required, it may be disabled by terminating the ts pin to in and ground using a 10k resistor divider network. if circuit power dissipation is a concern, the two terminating resistor values may be increased to 100k . aat3663-2 option most of the commonly used ntc thermistors in li- ion/polymer battery packs are approximately 10k at room temperature (25c). the aat3663-2 ts pin has been specifically designed to source 75a of current to the 10k ntc thermistor. the applied constant current source and fixed internal ts1 and ts2 voltage thresholds eliminate the need for a resistor divider on the ts pin. simply connect the 10k ntc resistor between the ts pin and ground. if the ts function is not needed for the aat3663-2, it may be left open (not connected). thermal considerations the aat3663 is offered in a 3x3mm tdfn package which can provide up to 2.0w of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50c/w. many considerations should be taken into account when designing the printed circuit board layout, as well as the placement of the charger ic package in proximity to other heat generating devices in a given application. the ambient temperature around the charger ic will also have an effect on the thermal lim- its of the battery charging operation. the maximum limits that can be expected for a given ambient con- dition can be estimated by the following discussion. aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 17 figure 4: external resistor and ntc thermistor application circuit. t in ts battery pack aat3663-4.2-1 or aat3663-8.4-1 battery cold fault battery hot fault 0.6xv in 0. 30 xv in r t r ntc v in
first, the maximum power dissipation for a given sit- uation should be calculated: where: p d(max) = maximum power dissipation (w) ja = package thermal resistance (c/w) t j = thermal loop entering threshold (oc) [115oc] t a = ambient temperature (c) figure 5 shows the relationship between maximum power dissipation and ambient temperature of aat3663 figure 5: maximum power dissipation before entering thermal loop. next, the power dissipation can be calculated by the following equation: where: p d = total power dissipation by the device v in = input voltage v bat = battery voltage as seen at the bat pin i ch = constant charge current programmed for the application i op = quiescent current consumed by the charger ic for normal operation [0.5ma] by substitution, we can derive the maximum charge current before reaching the thermal limit condition which will activate digital thermal loop operation. the maximum charge current is the key factor when designing battery charger applications. in general, the worst case condition is when the great- est input to output voltage drop occurs across the charger ic. specifically when battery voltage is charged up just above the preconditioning voltage threshold and the charger enters into the constant current fast charging mode. under this condition, the device will suffer the maximum possible power dissi- pation since both the voltage difference across the device and the charge current will be at their respec- tive maximums. figure 6 shows the safe fast charge current operating region for different ambient temper- atures. exceeding these limits will drive the charge control into digital thermal loop operation. when under digital thermal loop operation, the device will remain active and continue to charge the battery at a reduced current level for the given ambient condition. figure 6: maximum charging current before the digital thermal loop becomes active. capacitor selection input capacitor in general, it is a good design practice to place a decoupling capacitor between the in pin and ground. an input capacitor in the range of 1f to 22f is rec- ommended. if the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lock- out threshold during device enable and when battery charging is initiated. if the aat3663s input is to be used in a system with an external power supply source, such as a typical ac-to-dc wall adapter, v in (v) i cc(max) (ma) 0 200 400 600 800 1000 4 5 6 7 8 9 10 11 12 13 t a = 85c t a = 60c t a = 25c t a = 45c (t j - t a ) ja v in - v bat i ch(max) = - v in i op (p d(max) - v in i op ) v in - v bat i ch(max) = t a (c) p d(max) (w) 0.00 0.50 1.00 1.50 2.00 2.50 0 25 50 75 100 (t j - t a ) p d(max) = ja aat3663 1a linear li-ion battery charger for single and dual cell applications 18 3663.2007.10.1.0
aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 19 figure 7: aat3663 evaluation board figure 8: aat3663 evaluation board top (component) side layout. bottom side layout. then a c in capacitor in the range of 10f should be used. a larger input capacitor in this application will minimize switching or power transient effects when the power supply is "hot plugged" in. output capacitor the aat3663 only requires a 1f ceramic capaci- tor on the bat pin to maintain circuit stability. this value should be increased to 10f or more if the battery connection is made any distance from the charger output. if the aat3663 is to be used in applications where the battery can be removed from the charger, such as desktop charging cra- dles, an output capacitor 10f or greater is recom- mended to reduce the effect of the charger cycling on and off when no battery is present. printed circuit board layout considerations for the best results, it is recommended to physically place the battery pack as close as possible to the aat3663 bat pin. to minimize voltage drops on the pcb, keep the high current carrying traces ade- quately wide. for maximum power dissipation of the aat3663 3x3mm 14-pin tdfn package, the metal substrate should be solder bonded to the board. it is also recommended to maximize the substrate con- tact to the pcb ground plane layer to further increase local heat dissipation. refer to the aat3663 evaluation board for a good layout example.
figure 9: aat3663 evaluation board schematic diagram. c2 0805 x7r 10f 10v grm21br71a106ke51l c1 1206 x7r 10f 16v grm31cr71c106kac7l 2k r4 d1 c1 10f c2 10f c3 0.1f enable jp1 r2 10k r1 1.74k 2k r5 d2 2k r6 d3 r3 10k 4v - 13.2v r7 (see note) jp3 jp2 jp4 vin gnd gnd bat ts vin en 1 in 9 gnd 4 ts 5 stat2 10 in 8 stat1 11 bats 6 bat 7 iset 3 term 13 adpp# 12 ct 2 ep u1 tdfn33-14 aat3663 note: r2 = 10k is set the termination current, 7.5% from the constant charging current r7 = 10k (for -1 option) r7 = open (for -2 option) green led red led red led aat3663 1a linear li-ion battery charger for single and dual cell applications 20 3663.2007.10.1.0
aat3663 1a linear li-ion battery charger for single and dual cell applications 3663.2007.10.1.0 21 ordering information all analogictech products are offered in pb-free packaging. the term pb-free means semiconductor products that are in compliance with current rohs standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. for more information, please visit our website at http://www.analogictech.com/pbfree. battery cell part number voltage option battery temperature sense package marking 1 (tape and reel) 2 single cell (4.2v) for use with any ntc thermistor tdfn33-14 aat3663iwo-4.2-1-t1 single cell (4.2v) for use with 10k ntc thermistor tdfn33-14 zzxyy aat3663iwo-4.2-2-t1 dual cell (8.4v) for use with any ntc thermistor tdfn33-14 aat3663iwo-8.4-1-t1 dual cell (8.4v) for use with 10k ntc thermistor tdfn33-14 aat3663iwo-8.4-2-t1 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold .
aat3663 1a linear li-ion battery charger for single and dual cell applications 22 3663.2007.10.1.0 advanced analogic technologies, inc. 3230 scott boulevard, santa clara, ca 95054 phone (408) 737-4600 fax (408) 737-4611 ? advanced analogic technologies, inc. analogictech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an analogictech pr oduct. no circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. analogictech reserves the right to make changes to their products or specifications or to discontinue any product or service with- out notice. except as provided in analogictechs terms and conditions of sale, analogictech assumes no liability whatsoever, an d analogictech disclaims any express or implied war- ranty relating to the sale and/or use of analogictech products including liability or warranties relating to fitness for a part icular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. in order to minimize risks associated with the customers applications, adequa te design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. testing and other quality control techniques are utilized to the extent an alogictech deems necessary to support this warranty. specific testing of all parameters of each device is not necessarily performed. analogictech and the analogictech logo are trad emarks of advanced analogic technologies incorporated. all other brand and product names appearing in this document are registered trademarks or trademarks of their respective holder s. package information tdfn33-14 all dimensions in millimeters. top view bottom view 3.000 +

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