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aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 1 batterymanager ? general description the aat3681 batterymanager is an integrated sin- gle cell lithium-ion/polymer battery charger ic, designed to operate from a dc power source or usb port up to an input voltage of 6.5v. it requires just one external component. the aat3681 precisely regulates battery charge voltage and current for 4.2v (4.375v option) lithium- ion/polymer battery cells. when charged from an ac adapter or usb port, the battery charging cur- rent can be set by an external resistor up to 300ma. battery charge state is continuously monitored for fault conditions. in the event of an over-voltage, short-circuit, or over-temperature failure, the device will automatically shut down, thus protecting the charging device, control system, and the bat- tery under charge. a status monitor output pin is provided to indicate the battery charge status by directly driving an external led. the aat3681 is available in a pb-free, thermally enhanced, space-saving 8-pin 2.0x2.1mm sc70jw package and is specified for operation over the -40c to +85c temperature range. features ? usb or ac adapter system power charger ? programmable from 15ma to 300ma ? 4.0v ~ 6.5v input voltage range ? high level of integration with internal: ? charging device ? reverse blocking diode ? automatic current sensing ? automatic recharge sequencing ? full battery charge auto turn off/sleep mode/charge termination ? shutdown current <1a ? automatic trickle charge for battery pre- conditioning (aat3681-1 is no trickle charge option) ? over-voltage and emergency thermal protection ? power on reset and soft start ? led status pin ? 8-pin 2.0x2.1mm sc70jw package applications ? bluetooth ? headsets ? dect headsets ? digital still cameras ? mp3, portable music, and portable media players ? personal data assistants (pdas) ? wrist watches ? other lithium-ion/polymer battery-powered devices typical application aat3681 c batt- battery pack adp gnd bat batt+ r set a dapter/usb input stat en iset enable
pin description pin configuration sc70jw-8 (top view) pin # symbol type function 1 en in enable pin. logic high enables the ic (internally pulled down). 2 iset in/out connect resistor here to set the charge current. 3 bat in/out battery charging and sensing. 4 adp power in input from usb/adapter charger. 5 stat out open drain status pin. 6, 7, 8 gnd power ground connection. aat3681 usb port or ac adapter lithium-ion/polymer battery charger 2 3681.2007.01.1.2 iset bat adp gnd gnd gnd sta t en 1 2 3 45 6 7 8
aat3681 feature options absolute maximum ratings 1 thermal information 2 symbol description value units p d maximum power dissipation 0.687 w ja maximum thermal resistance 160 c/w symbol description value units v p adp continuous -0.3 to 7.5 v v n bat, stat, iset, en -0.3 to v p + 0.3 v t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads) 300 c product trickle charge aat3681 yes aat3681-1 no aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 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 an fr4 board.
electrical characteristics 1 v adp = 5v, t a = -25c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units operation v adp adapter voltage range 4.0 6.5 v v uvlo under-voltage lockout (uvlo) rising edge 3 4 v uvlo hysteresis 150 mv i op operating current charge current = 200ma 0.5 1 ma i shutdown shutdown current v bat = 4.25v, en = gnd 0.3 1 a i leakage reverse leakage current from bat pin v bat = 4v, adp pin open 0.4 2 a voltage regulation v bat _ eoc end of charge accuracy 4.158 4.20 4.242 v v ch /v ch output charge voltage tolerance 0.5 % v min preconditioning voltage threshold aat3681 only 2.85 3.0 3.15 v v rch battery recharge voltage threshold measured from v bat _ eoc -0.1 v current regulation i ch charge current programmable range 15 300 ma i ch /i ch charge current regulation tolerance 10 % v set iset pin voltage 2 v k i _ a current set factor: i ch /i set 800 charging devices r ds(on) charging transistor on resistance v adp = 5.5v 0.9 1.1 logic control/protection v en(h) input high threshold 1.6 v v en(l) input low threshold 0.4 v v s tat output low voltage stat pin sinks 4ma 0.4 v i s tat stat pin current sink capability 8 ma v ovp over-voltage protection threshold 4.4 v i tk /i ch pre-charge current i ch = 100ma; aat3681 only 10 % i term /i ch charge termination threshold current 10 % aat3681 usb port or ac adapter lithium-ion/polymer battery charger 4 3681.2007.01.1.2 1. the aat3681 output charge voltage is specified over the 0 to 70c ambient temperature range; operation over the -25c to +8 5c temperature range is guaranteed by design.
typical characteristics aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 5 constant charging current vs. supply voltage (r set = 8.06k ) v in (v) i ch (ma) 170 180 190 200 210 220 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 v bat = 3.6v v bat = 4v v bat = 3.3v end of charge voltage regulation vs. temperature (r set = 8.06k ) temperature ( c) v bat_eoc (v) 4.17 4.18 4.19 4.20 4.21 4.22 4.23 -50 -25 0 25 50 75 100 end of charge battery voltage vs. supply voltage v in (v) v bat_eoc (v) 4.194 4.196 4.198 4.200 4.202 4.204 4.206 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 r set = 8.06k r set = 31.6k charging current vs. battery voltage (aat3681-1 only) v bat (v) i ch (ma) 0 100 200 300 400 500 600 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 r set = 3.24k r set = 5.36k r set = 8.06k r set = 16.2k r set = 31.6k charging current vs. battery voltage (aat3681 only) v bat (v) i ch (ma) 0 50 100 150 200 250 300 350 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 r set = 8.06k r set = 5.36k r set = 16.2k r set = 31.6k r set (k ) i ch (ma) 1 10 100 1000 1 10 100 1000 constant charging current vs. set resistor values
typical characteristics aat3681 usb port or ac adapter lithium-ion/polymer battery charger 6 3681.2007.01.1.2 preconditioning charge current vs. supply voltage (aat3681 only) v in (v) i trickle (ma) 0 5 10 15 20 25 30 35 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6. 5 r set = 8.06k r set = 5.36k r set = 16.2k r set = 31.6k preconditioning charge current vs. temperature (r set = 8.06k ; aat3681 only) temperature ( c) i trickle (ma) 19.2 19.4 19.6 19.8 20.0 20.2 20.4 20.6 20.8 -50 -25 0 25 50 75 100 preconditioning threshold voltage vs. temperature (r set = 8.06k ; aat3681 only) temperature ( c) v min (v) 2.97 2.98 2.99 3 3.01 3.02 3.03 -50 -25 0 25 50 75 100 operating current vs. temperature (r set = 8.06k ) temperature ( c) i op (a) 300 350 400 450 500 550 -50 -25 0 25 50 75 100 operating supply current vs. set resistor r set (k ) i op (a) 10 100 1000 1 10 100 v bat = 2.85v v bat = 3.6v constant charging current vs. temperature (r set = 8.06k ) temperature ( c) i ch (ma) 190 193 195 198 200 203 205 208 210 -50 -25 0 25 50 75 100
typical characteristics aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 7 v il_enable vs. supply voltage (r set = 8.06k ) v in (v) v il_enable (v) 0.6 0.7 0.8 0.9 1 1.1 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 -40 c 25 c 85 c v ih_enable vs. supply voltage (r set = 8.06k ) v in (v) v ih_enable (v) 0.7 0.8 0.9 1 1.1 1.2 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 -40 c 25 c 85 c sleep mode current vs. supply voltage (r set = 8.06k ) v in (v) i sleep (na) 0 100 200 300 400 500 600 700 800 4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 85 c 25 c -40 c recharging threshold voltage vs. temperature (r set = 8.06k ) temperature ( c) v rch (v) 4.02 4.04 4.06 4.08 4.10 4.12 4.14 4.16 4.18 -50 -25 0 25 50 75 100
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 8 3681.2007.01.1.2 functional block diagram functional description the aat3681 is a high performance battery charg- er designed to charge single cell lithium-ion/poly- mer batteries with up to 300ma of current from an external power source. it is a stand-alone charging solution, with just one external component required for complete functionality. the aat3681 precisely regulates battery charge voltage and current for 4.2v lithium-ion/polymer battery cells. the adapter/usb charge input constant current level can be programmed up to 300ma for rapid charging applications. the aat3681 is rated for operation from -40c to +85c. in the event of oper- ating ambient temperatures exceeding the power dissipation abilities of the device package for a given constant current charge level, the charge control will enter into thermal limit. a status monitor output pin is provided to indicate the battery charge state by directly driving one external led. device junction temperature and charge state are fully monitored for fault conditions. in the event of an over-voltage or over-temperature failure, the device will automatically shut down, protecting the charging device, control system, and the battery under charge. charging operation the aat3681 has four basic modes for the battery charge cycle: pre-conditioning/trickle charge; con- stant current/fast charge; constant voltage; and end of charge (see figure 1). (aat3681-1 does not have trickle charge.) charge control current compare reverse blocking cv/ precharge constant current adp bat iset uvlo over- temperature protection charge status stat gnd en
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 9 battery preconditioning before the start of charging, the aat3681 checks several conditions in order to assure a safe charging environment. the input supply must be above the minimum operating voltage, or under-voltage lock- out threshold (v uvlo ), for the charging sequence to begin. when these conditions have been met and a battery is connected to the bat pin, the aat3681 checks the state of the battery. if the cell voltage is below the preconditioning voltage threshold (v min ), the charge control begins preconditioning the cell. the battery preconditioning trickle charge current is equal to the fast charge constant current divided by 10. for example, if the programmed fast charge cur- rent is 300ma, then the preconditioning mode (trick- le charge) current will be 30ma. cell preconditioning is a safety precaution for deeply discharged battery cells and also aids in limiting power dissipation in the pass transistor when the voltage across the device is at the greatest potential. constant current charging battery cell preconditioning continues until the volt- age on the bat pin exceeds the preconditioning voltage threshold (v min ). at this point, the aat3681 begins the constant current charging phase. the charge constant current (i ch ) amplitude is pro- grammed by the user via the r set resistor. the aat3681 remains in the constant current charge mode until the battery reaches the voltage regula- tion point, v bat_eoc . constant voltage charging the system transitions to a constant voltage charg- ing mode when the battery voltage reaches the output charge regulation threshold (v bat_eoc ) dur- ing the constant current fast charge phase. the regulation voltage level is factory programmed to 4.2v (0.5%). charge current in the constant volt- age mode drops as the battery cell under charge reaches its maximum capacity. end of charge cycle termination and recharge sequence when the charge current drops to 10% of the pro- grammed fast charge current level in the constant voltage mode, the device terminates charging and goes into a sleep state. the charger will remain in a sleep state until the battery voltage decreases to a level below the battery recharge voltage thresh- old (v rch ). when the input supply is disconnected, the charg- er will automatically transition into a power-saving sleep mode. only consuming an ultra-low 0.3a in sleep mode, the aat3681 minimizes battery drain when it is not charging. this feature is particularly useful in applications where the input supply level may fall below the battery charge or under-voltage lockout level. in such cases where the aat3681 input voltage drops, the device will enter sleep mode and automatically resume charging once the input supply has recovered from the fault condition. figure 1: current vs. 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
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 10 3681.2007.01.1.2 system operation flow chart power on reset power input voltage v in > v uvlo fault conditions monitoring ov, ot preconditioning test v min > v bat current phase test v in > v bat voltage phase test i bat > i term no (aat3681) no yes no preconditioning (trickle charge) constant current charge mode constant voltage charge mode yes yes yes charge completed charge control no recharge test v rch > v bat yes no shut down yes enable yes no no (aat3681-1)
application information adapter or usb power input constant current charge levels up to 300ma may be programmed by the user when powered from a sufficient input power source. the aat3681 will operate from the adapter input over a 4.0v to 6.5v range. the constant current fast charge current for the adapter input is set by the r set resistor con- nected between iset and ground. refer to table 1 for recommended r set values for a desired con- stant current charge level. adapter input charge inhibit and resume the aat3681 has a uvlo and power on reset fea- ture so that if the input supply to the adp pin drops below the uvlo threshold, the charger will sus- pend charging and shut down. when power is re- applied to the adp pin or the uvlo condition recovers, the system charge control will assess the state of charge on the battery cell and will auto- matically resume charging in the appropriate mode for the condition of the battery. enable / disable the aat3681 provides an enable function to con- trol the charger ic on and off. the enable (en) pin is internally pulled down. when pulled to a logic high level, aat3681 is enabled. when left open or pulled to a logic low level, the aat3681 will be shut down and forced into the sleep state. charging will be halted regardless of the battery voltage or charging state. when the device is 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 cell voltage on the bat pin. programming charge current the fast charge constant current charge level is user programmed with a set resistor placed between the iset pin and ground. the accuracy of the fast charge, as well as the preconditioning trick- le charge current, is dominated by the tolerance of the set resistor used. for this reason, a 1% toler- ance metal film resistor is recommended for the set resistor function. fast charge constant current lev- els from 15ma to 300ma may be set by selecting the appropriate resistor value from table 1. table 1: r set values. figure 2: constant charging current vs. set resistor values. protection circuitry over-voltage protection an over-voltage event is defined as a condition where the voltage on the bat pin exceeds the maximum battery charge voltage and is set by the over-voltage protection threshold (v ovp ). if an over- voltage condition occurs, the aat3681 charge con- trol will shut down the device until voltage on the bat pin drops below v ovp . the aat3681 will resume normal charging operation after the over- voltage condition is removed. over-temperature shutdown the aat3681 has a thermal protection control circuit which will shut down charging functions should the internal die temperature exceed the preset thermal limit threshold. once the internal die temperature falls below the thermal limit, normal operation will resume the previous charging state. nominal set resistor i charge (ma) value (k ) 300 5.36 250 6.49 200 8.06 150 10.7 100 16.2 50 31.6 40 38.3 30 53.6 20 78.7 15 105 aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 11 r set (k ) i ch (ma) 1 10 100 1000 1 10 100 1000
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 12 3681.2007.01.1.2 charge status output the aat3681 provides battery charge status via a status pin. this pin is internally connected to an n- channel open drain mosfet, which can be used to drive an external led. the status pin can indicate the following conditions: table 2: led status indicator. 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 formulas: example: note: red led forward voltage (v f ) is typically 2.0v @ 2ma. thermal considerations the aat3681 is offered in a sc70jw-8 package which can provide up to 687mw of power dissipa- tion when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 160c/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 gen- erating devices in a given application design. the ambient temperature around the charger ic will also have an effect on the thermal limits of a bat- tery charging application. the maximum limits that can be expected for a given ambient condition can be estimated by the following discussion. first, the maximum power dissipation for a given situation should be calculated: where: p d(max) = maximum power dissipation (w) ja = package thermal resistance (c/w) t j(max) = maximum device junction temperature (c) [135c] t a = ambient temperature (c) figure 3 shows the relationship of maximum power dissipation and ambient temperature of aat3681. figure 3: maximum power dissipation. next, the power dissipation can be calculated by the following equation: event description status no battery charging activity off battery charging via adapter on or usb port charging completed off p d = [(v in - v bat ) i ch + (v in i op )] t a ( c) p d(max) (mw) 0 200 400 600 800 1000 0 20 40 60 80 100 (t j(max) - t a ) p d(max) = ja (5.5v - 2.0 v) r 1 = = 1.75k 2ma (v adp - v f(led) ) r 1 = i led
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 (thermal cycling). the maximum charge current is the key factor when designing battery charger applications. in general, the worst condition is the greatest volt- age drop across the charger ic, when battery volt- age is charged up to the preconditioning voltage threshold. figure 4 shows the maximum charge current in different ambient temperatures. figure 4: maximum charging current before thermal cycling becomes active. capacitor selection input capacitor in general, it is good design practice to place a decoupling capacitor between the adp pin and gnd. an input capacitor in the range of 1f to 22f is recommended. if the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. if the aat3681 adapter input is to be used in a system with an external power supply source, such as a typical ac-to-dc wall adapter, 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 aat3681 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 aat3681 is to be used in applications where the battery can be removed from the charger, such as with desktop charging cradles, an output capacitor greater than 10f may be required to prevent the device from 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 aat3681 bat pin. to minimize voltage drops on the pcb, keep the high current carrying traces ade- quately wide. refer to the aat3681 evaluation board for a good layout example (see figures 5 and 6). aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 13 v in (v) i ch(max) (ma) 0 50 100 150 200 250 300 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.7 5 t a = 25 c t a = 60 c t a = 85 c t a = 45 c (t j(max) - 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) =
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 14 3681.2007.01.1.2 figure 5: aat3681 evaluation board figure 6: aat3681 evaluation board top layer. bottom layer. figure 7: aat3681 evaluation board schematic diagram. table 3: aat3681 evaluation board bill of materials. component part number description manufacturer u1 aat3681ijs-t1 usb/adp battery charger; analogictech sc70jw-8 package r1 chip resistor 1k , 5%, 1/4w; 0603 vishay r8 chip resistor 8.06k , 1%, 1/4w; 0805 vishay jp1 chip resistor 0 , 5%, 1/4w; 0603 vishay c1 grm21br61a106ke19l cer 10f 10v 10% x5r 0805 murata c2 grm21br71a225ka01l cer 2.2f 10v 10% x7r 0805 murata jp2 prpn401paen connecting header, 2mm zip sullins electronics led1 cmd15-21src/tr8 red led; 1206 chicago miniature lamp red led d1 r1 1k 10f c1 2.2f c2 v in(adp) v bat 8.06k r8 jp2 jp1 0 en 1 iset 2 bat 3 adp 4 stat 5 gnd 6 gnd 7 gnd 8 aat3681 u1 (sc70jw-8)
aat3681 usb port or ac adapter lithium-ion/polymer battery charger 3681.2007.01.1.2 15 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737- 4600 fax (408) 737- 4611 ordering information package information sc70jw-8 all dimensions in millimeters. trickle charge package marking 1 part number (tape and reel) 2 yes sc70jw-8 rexyy aat3681ijs-4.2-t1 no sc70jw-8 stxyy aat3681ijs-4.2-1-t1 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . ? 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 specifi cations or to discontinue any product or service without notice. customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information b eing relied on is current and complete. all products are sold sub- ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. analogictech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with anal ogictech?s standard warranty. testing and other quality con- trol techniques are utilized to the extent analogictech deems necessary to support this warranty. specific testing of all param eters of each device is not necessarily performed. analogictech and the analogictech logo are trademarks of advanced analogic technologies incorporated. all other brand and produ ct names appearing in this document are regis- tered trademarks or trademarks of their respective holders. 0.225 0.075 0.45 0.10 0.05 0.05 2.10 0.30 2.00 0.20 7 3 4 4 1.75 0.10 0.85 0.15 0.15 0.05 1.10 max 0.100 2.20 0.20 0.048ref 0.50 bsc 0.50 bsc 0.50 bsc 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.

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