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skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 1 data sheet aat3620: single cell li+ switch mode battery charger applications ? digital camcorders ? point of service (pos) ? portable dvd players ? portable hand-held solutions ? portable media players features ? input voltage range: 4.3 to 6.0 v ? up to 2.0 a charging current capability ? 1.5 mhz pwm/linear charger ? over 90% full rate charging efficiency ? integrated switching device ? no bat detect ? safety timer ? integrated sense resistor ? built-in reverse blocking feature ? battery preconditioning/constant-voltage/constant-current charging mode ? programmable end-of-charging current ? 1% constant-voltage mode regulation ? built-in programmable charging timer ? charging current indication pin ? over-voltage, over-current, and over-temperature protection ? battery over-temperature protection ? power-on reset and soft-start ? space-saving tdfn (14-pin, 3 mm ? 3 mm) package (msl1, 260 oc per jedec j-std-020) s kywork s green? product s are compliant with all applicable legi s lation and are halogen-free. for additional information, refer to skyworks de?ition of green , document number s q04-0074. description the batterymanager? aat3620 is an ideal solution for charging high-capacity li+ batteries. the aat3620 can supply up to 2.0 a charging current with minimal thermal impact to mobile systems with features such as color display, camera with flash, organizer, video, etc., that requires battery capacity to keep pace with the power requirements. the aat3620 is a pulse-width modulation (pwm) switch mode/linear charger with high charging efficiency at the full constant-current (fast charge) rate. based on a 1.5 mhz pwm step-down buck converter, the aat3620 pwm switch mode controls the constant-current charging mode up to 2.0 a, and automatically switches to linear mode charging during the battery conditioning low level current and the light load end-of-charging current termination region. the full charging rate and the end-of- charging current can be programmed with separate external resistors. a shared charging current indication pin is available for a coulomb counter. battery charger temperature and charging state are fully monitored for fault conditions. in the event of an over-current, over-voltage, short-circuit or over-temperature failure, the device automatically shuts down. two status monitor output pins are provided to indicate the battery charging status and power source status through two display leds. the aat3620 also has a no- battery detection feature, "no bat", which requires the safety timer. the aat3620 is available in a thermally enhanced, space-saving 14-pin, 3 mm ? 3 mm tdfn package. a typical application circuit is shown in figure 1. the pin configurations are shown in figure 2. signal pin assignments and functional pin descriptions are provided in table 1. downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 2 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without noti ce ? 201904d batt - temp battery pack vpinen t s lx batt + adapter cs bat pgnd s tat 2 s tat 1 c t gnd c harge enable c harging s tatu s 1 c harging s tatu s 2 i s et iterm termination c urrent s et & c harge c urrent indicator c harge c urrent s et v cc v cc aat3 6 20 rt1 rt2 r term r s et 10 f 22 f 0.1 f 0.1 f 100 1 f 4.7 h tc93 figure 1. aat3620 typical application circuit vpin pgnd gnd 1 v cc en i s et lx ep csbat t s term s tat1 2 3 4 5 6 c t 7 12 11 1413 10 9 s tat2 8 t0109 figure 2. aat3620 pinout C 14-pin, 3 mm ? 3 mm tdfn (top view) downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 3 table 1. aat3620 signal descriptions pin # name type description 1 vpin in adapter power input. 2 p g nd g round power ground. 3 g nd g round analog ground connection. 4 vcc in supply input. 5 en in charging enable input, active high, with internal pull-up (to vpin). 6 iset in connect r set resistor to pin to set constant-current charging current. 7 ct in/out timer pin. connect timing ca pacitor here for charging timer function. 8 stat2 out battery charging status 2 indicator pin to drive an led, open-drain. 9 stat1 out battery charging status 1 indicator pin to drive an led, open-drain. 10 term in/out connect r term resistor to pin to set termination current. charging current can be monitored with this pin. leave open to set to 200 ma default termination current. 11 ts in/out battery pack temperature sensing input. to disable ts function, pull up to v cc through 10 k ? resistor. 12 bat out battery positive terminal connecting pin. 13 cs in return pin for inductor for internal current sensing. 14 lx in/out switching node. ep ep g round the exposed thermal pad (ep) must be connected to the bo ard ground plane and pins 2 a nd 3. the ground plane should include a large exposed copper pad under the packag e for thermal dissipatio n (see package outline). electrical and mechanical specifications the absolute maximum ratings of the aat3620 are provided in table 2, the thermal information is listed in table 3, and electrical specifications are provided in table 4. table 2. aat3620 absolute maximum ratings (note 1) parameter symbol minimum typical maximum units vpin, lx v p ? 0.3 +6.5 v other pins v n ? 0.3 v p + 0.3 v operating junction temperature range t j ? 40 + 150 oc maximum power dissipation p d 2.5 w maximum soldering temperature (at leads) t lead 300 oc note 1: exposure to maximum rating conditions for extended periods may reduce device reliability. there is no damage to device with onl y one parameter set at the limit and all other parameters set at or below their nominal value. exceeding any of the limits listed may result in permanent damage to the device . table 3. aat3620 thermal information parameter symbol value units maximum thermal resistance (note 1) ? ja 50 oc/w maximum power dissipation (note 2) p d 2 w note 1: mounted on an fr4 board. note 2: derate 2.7 mw/ ? c above 25 ? c ambient temperature. caution: although this device is designed to be as robust as possible, electrostatic discharge (esd) can damage this device. this devic e must be protected at all times from esd. static charges may ea sily produce potentials of several kilovolts on the human body or equipment, which can discharge without detection. industr y-standard esd precautions should be used at all times. downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 4 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without noti ce ? 201904d table 4. aat3620 electrical specifications (1 of 2) (note 1) (v in = 5.5 v, t a = C25 ? c to +85 ? c, unless otherwise noted, typical values are t a = 25 ? c) parameter symbol test condition min typical max units operation adapter input voltage v in 4.3 6.0 v input under-voltage lockout v cc _ uvlo v pin rising 3.5 4.3 v hysteresis 150 v input sleep voltage v vin _ sleep no charging if v vin < v vin _ sleep v bat + 0.05 v bat + 0.2 mv operating supply current i vin _ op en = high, charging current = 200 ma 5 ma standby supply current i vin _ stby en = high, no charge, power-saving mode 2 ma shutdown supply current i vin _ shdn en = low, lx floating, sleep mode 10 ? a forward leakage current, measured from lx to ground i fwd _ lk g en = low, lx = 5.5 v 1 ? a reverse leakage current, measured from lx to v in i rev _ lk g en = low or high, v in = 0 v, lx = 5.5 v 1 ? a bat pin leakage current i bat _ lk g v bat = 4.2 v, v in = 0 v or open 1 ? a internal pmos on resistance r ds ( on ) v in = 5.5 v 170 300 m ? internal nmos on resistance v in = 5.5 v 120 250 m ? pwm switching frequency f sw v bat = 3.6 v, i ch _ cc = 1 a 1.2 1.5 1.8 mhz charging regulation output charging voltage regulation v bat _ re g 4.158 4.2 4.242 v charging soft-start delay t soft _ start delay of charging from en, or v cc _ uvlo , or v vin _ adpp 100 ? s battery conditioning battery voltage threshold v bat _ bc preconditioning battery charging when v bat rising: v bat < v bat _ bc 2.4 2.6 2.8 v battery conditioning charging current i ch _ bc when v bat < v bat _ bc 0.1 ? i ch _ cc a typical battery conditioning charging current setting range i ch _ bc _ typ 100 200 ma battery conditioning time- out t ch _ bc stop charging if preconditioning time is more than t ch _ bc ? 15% 0.25 ? c ct +15% minute/nf constant-current battery charging current accuracy i ch _ cc when v bat _ bc < v bat < v bat _ re g , 1 a to 2 a ? 15% i ch _ cc +15 % fast constant-current charging time out t ch _ ccto stop charging if fast charging time is more than t ch _ ccfast ? 15% 0.022 ? c ct +15% hour/nf constant voltage charging time-out t ch _ cvto stop charging if charging time is more than t ch _ cv ? 15% 0.03 ? c ct +15% hour/nf battery recharging voltage threshold v bat _ rch if v bat falls below v bat _ rch , recharging starts v bat _ re g ? 0.1 v charging termination threshold current i ch _ term _ typ terminate cv charging if i ch < i ch _ term r term ? 10 ? 6 a typical termination threshold current setting range i ch _ term _ ran g e charger termination current is clamped to the minimum or maximum value if set above or below the i term range. 50 200 ma downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 5 table 4. aat3620 electrical specifications (2 of 2) (note 1) (v in = 5.5 v, t a = C25 ? c to +85 ? c, unless otherwise noted, typical values are t a = 25 ? c) parameter symbol test condition min typical max units logic and status input/output en input high threshold v ih 1.6 v en input low threshold v il 0.4 v en pin supply current i en en = v in 0.1 1 ? a en = 0 v 0.6 10 ? a stat1, stat2 pin leakage current i sleak when output fet is off 1 ? a stat1 and stat2 pin current sink capability i stat x 10 ma stat pulse width t stat _ pulse in fault conditions: c ct = 100 nf 0.5 s stat pulse frequency f stat _ flash in fault conditions: c ct = 100 nf 1 hz protection battery over-voltage protection threshold v bat _ ovp no charging if v bat > v bat _ ovp v bat _ re g + 0.2 v over-current protection threshold and limit i cl 2.46 3.0 4.0 a ts hot temperature fault v ts 1 threshold v ts falling 29.1 30 30.9 % v cc hysteresis 50 mv ts cold temperature fault threshold v ts 2 threshold v ts rising 58.2 60 61.8 % v cc hysteresis 50 mv thermal shutdown t sd 140 oc thermal shutdown hysteresis t sd _ hys 15 oc note 1: performance is guaranteed only under the conditions listed in this table. typical performance characteristics typical performance characteristics of the aat3620 are illustrated in figures 3 through 10. 0 300 6 00 9 00 1200 1500 1800 2100 2400 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 c harging c urrent (ma) battery voltage (v) C25 c 25 c 85 c figure 3. charging current vs battery voltage 0 250 500 750 1000 1250 1500 1750 2000 2250 10 30 50 70 9 01 1 0 fa s t c harge c urrent (ma) i s et re s i s tor (k ) figure 4. constant-current charging mode current vs iset resistor (v in = 5 v, v bat = 3.5 v) downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 6 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without noti ce ? 201904d temperature ( c ) termination c urrent (ma) -40 -15 10 35 6 08 5 40 42 44 4 6 48 50 52 54 5 6 58 6 0 6 2 6 4 figure 5. termination current vs temperature (v in = 5 v, r term = 49.9 k ? ) temperature ( c ) preconditioning ri s ing thre s hold voltage (v) -40 -15 10 35 6 08 5 2.5 6 2.57 2.58 2.5 9 2. 6 0 2. 6 1 2. 6 2 2. 6 3 2. 6 4 figure 7. preconditioning rising threshold voltage vs temperature (v in = 5.5 v) input voltage (v) battery c harging c urrent (ma) 4.0 4.4 4.8 5.2 5. 66 .0 4.2 4. 6 5.0 5.4 5.8 0 300 6 00 9 00 1200 1500 1800 2100 2400 v bat = 2.7 v v bat = 3.3 v v bat = 3. 6 v v bat = 3. 9 v figure 9. charging current vs input voltage (t = ? 25 c) temperature ( c ) end of c harging voltage (v) -40 -15 10 35 6 08 5 4.050 4.055 4.0 6 0 4.0 6 5 4.070 4.075 4.080 figure 6. recharging voltage vs temperature (v in = 5 v) 4.5 5.0 5.5 6 .0 input voltage (v) s hutdown c urrent ( a) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 C25 c 25 c 85 c figure 8. shutdown current vs input voltage input voltage (v) c harge c urrent (ma) 4.0 4.5 5.0 5.5 6 .0 6 .5 0 500 1000 1500 2000 2500 v bat = 2.7 v v bat = 3.3 v v bat = 3. 6 v v bat = 3. 9 v figure 10. charging current vs input voltage (t = 85 c) downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 7 pwm / linear c harge c ontrol rever s e blocking vpin v cc en bat i s et over-temperature protection lx cs c harge s tatu s t s c urrent s et gnd s tat2 timer c t pgnd rever s e blocking term vref s tat1 volt det / uvlo t0119 figure 11. aat3620 functional block diagram functional description control loop the aat3620 uses an average current mode step-down converter to implement the dc-dc switch-mode converter function during constant-current mode charging. the technique of average current mode control overcomes peak current control problems by introducing a high gain integrating current error amplifier into the current loop. average current tracks the sensed output current with a high degree of accuracy and excellent noise immunity. the oscillator sawtooth ramp provides compensation so no slope compensation is required for duty cycle exceeding 50%. the high gain of the current error amplifier at dc accurately programs the output. the switching charger works in continuous current mode pwm only. there is a soft start before entering constant-current charging mode and the charger re-enters linear operation in constant voltage mode when the charging current drops below 300 ma. a functional block diagram is shown in figure 11. linear vs switching battery charging the aat3620 performs battery charging using the benefits of the step-down or buck architecture to multiply the input current when stepping down the output voltage. this property maximizes battery charging from current limited devices and greatly decreases power and heat-related dissipation. the process is expressed mathematically in the following comparison: linear charging linear charging current relationship: in batl i i ? efficiency of linear charger: in bat v v ? ? switch-mode charging switch-mode current relationship: bat in in s bats v i v i ? ? ? ? where: ? s = 90%. example: power savings conventional linear charger ic: ? ??? w 75.0 5.0 5.3 5 i v v p bat bat in d ? ? ? ? ? ? ? switch-mode charger ic: ?? w 194 .0 5.0 5.3 9.0 5.0 5.3 i v i v p bat bat bat bat d ? ? ? ? ? ? ? ? ? ? downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 8 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without noti ce ? 201904d adapter input charging inhibit and resume the aat3620 has a uvlo and power-on reset feature so that if the input supply to the adp pin drops below the uvlo threshold, the charger suspends charging and shuts down. when power is re-applied to the in pin or the uvlo condition recovers, the system charging control assesses the state of charging on the battery cell and automatically resumes charging in the appropriate mode for the condition of the battery. input/output capacitor and inductor the aat3620 contains a high-performance 2 a, 1.5 mhz synchronous step-down converter. the step-down converter operates to ensure high efficiency performance over all load conditions. it requires only 3 external power components (c in , c out , and l). apart from the input capacitor, only a small l-c filter is required at the output side for the step-down converter to operate properly. typically, a 4.7 ? h inductor such as the wurth 7447789004 and a 22 ? f to 47 ? f ceramic output capacitor is recommended for low output voltage ripple and small component size. ceramic capacitors with x5r or x7r dielectrics are highly recommended because of their low esr and small temperature coefficients. a 10 ? f ceramic input capacitor is sufficient for most applications. battery charging battery charging starts only after the aat3620 checks several conditions to maintain a safe charging environment. the input supply must be above the minimum operating voltage (uvlo) and above the battery voltage by 0.3 v, the battery temperature must be within the 0 c ~ 45 c range, and the enable pin must be high. the aat3620 checks the condition of the battery and determines which charging mode to apply. if the battery voltage is below v bat _ bc , the aat3620 begins battery conditioning until the battery voltage reaches v bat _ bc . the battery conditioning current is 10% of constant-current level. once the aat3620 reaches v bat _ bc , it begins constant-current mode charging. the constant-current mode current level is programmed using a single resistor from the iset pin to ground. programmed current can be set from a minimum of 1 a to a maximum of 2 a. constant-current charging continues until the battery voltage reaches the voltage regulation point v bat _ re g . when the battery voltage reaches v bat _ re g , the aat3620 transitions to constant- voltage mode. the regulation voltage is factory programmed to a nominal 4.2 v and continues charging until the charging current is reduced to the termination current programmed by the resistor connected from iterm to ground. the termination current program range is 50 to 200 ma. after the charging cycle is complete, the aat3620, turns off the series pass device and automatically goes into a power saving mode. during this time, the series pass device blocks current in both directions, preventing the battery from discharging through the ic. the aat3620 shuts down if the charger source is disconnected until the charging source is reconnected and v in is greater than the v in _ sleep threshold. figure 12 illustrates the entire battery charging profile, which consists of three phases: 1. preconditioning-current mode (trickle) charging 2. constant-current mode charging 3. constant-voltage mode charging c on s tant- c urrent fa s t c harging pha s e preconditioning trickle c harging ph a s e c harging c omplete regulated voltage 4.2 c on s tant- c urrent mode voltage thre s hold 2. 6 regulated c urrent 1 c trickle c harging and termination thre s hold (programmable) battery recharging voltage thre s hold battery di s charging c on s tant-voltage taper c harging pha s e c on s tant-voltage taper c harging pha s e v i 300 time ma l s l s l c harging pha s e c on s tant- c urrent 1 2 3 2 3 t0220 the pro?le con s i s t s of three pha s e s : 1. preconditioning- c urrent mode (trickle) c harging - linear mode 2. c on s tant- c urrent (fa s t) mode c harging - s witching mode 3. c on s tant-voltage mode (taper) c harging - s witching/linear mode. figure 12. charging current and battery voltage vs time downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 9 the battery preconditioning current is equal to 10% of the constant-current charging level, so the battery preconditioning current range is 100 to 200 ma. linear mode is on standby while switch-mode is active in the constant-current charging region 2.6 v < v bat < 4.2 v. the charger re-enters linear mode while in constant voltage mode after the switch-mode current drops below 300 ma. the termination current is programmed by an external resistor with a separate iterm pin and the termination current set pin also monitors the charging current. the output short circuit current is equal to the battery preconditioning current. preconditioning trickle charge battery charging starts only after the aat3620 battery charger checks several conditions in order to maintain a safe charging environment. the system operation flow chart for the battery charger operation is shown in figure 13. the input supply must be above the minimum operating voltage (uvlo) and the enable pin (en) must be high (it is internally pulled up). when the battery is connected to the bat pin, the battery charger checks the condition of the battery and determines which charging mode to apply. preconditioning C current mode charging current if the battery voltage is below the preconditioning voltage threshold v ch _ bc , the battery charger initiates precondition trickle charging mode and charges the battery at 10% of the programmed constant-current magnitude. for example, if the programmed current is 1 a, the trickle charging current would be 100 ma. trickle charging is a safety precaution for a deeply discharged cell. it also reduces the power dissipation in the internal series pass mosfet when the input-output voltage differential is at its highest. constant C current mode charging current trickle charging continues until the battery voltage reaches v bat _ bc . at this point the battery charger begins constant- current charging. the current level default for this mode is programmed using a resistor from the iset pin to ground. programmed current can be set at a minimum of 100 ma and up to a maximum of 2.0 a. the aat3620 contains a high performance 2 a, 1.5 mhz synchronous step-down converter. the step-down converter operates to ensure high efficiency performance over all load conditions. it requires only 3 external power components (c in , c out , and l). constant C voltage mode charging constant-current charging continues until the battery voltage reaches the output charging voltage regulation point v bat _ re g . when the battery voltage reaches v bat _ re g , the battery charger transitions to constant-voltage mode. v bat _ re g is factory programmed to 4.2 v (nominal). charging in constant-voltage mode continues until the charging current is reduced to the programmed end-of-charging termination current. power-save mode after the charging cycle is complete, the battery charger turns off the series pass device and automatically goes into power- save mode. during this time, the series pass device blocks current in both directions to prevent the battery from discharging through the battery charger. in power-save mode, the battery charger monitors all parameters and resumes charging in the most appropriate mode. sleep mode the battery charger shuts down if the charger source is disconnected and v in is less than v in _ sleep threshold. it comes out of sleep mode if either v in is greater than v in _ sleep or en pin is cycled high while v in is greater than v in _ sleep . programming charging current (iset) the default constant-current mode charging level is user- programmed with a set resistor placed between the iset pin and ground. the accuracy of the constant charging current, as well as the preconditioning trickle charging current, is dominated by the tolerance of the set resistor. for this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. the constant charging current levels from 1 to 2 a can be set by selecting the appropriate resistor value from table 5. table 5. iset resistor vs constant-current mode current r set (k ? ) i ch _ cc (ma) 100 2000 90 1800 80 1600 70 1400 60 1200 50 1000 40 800 30 600 20 400 downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 10 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without not ice ? 201904d power on reset power input voltage v cc > v cc _ uvlo fault conditions monitoring ov, ot, preconditioning test current phase test voltage phase test no no yes no preconditioning (trickle charge) constant current charging mode constant voltage charging mode yes yes yes charging completed charging timer control no recharging test yes no shut down yes enable yes no no expired v ts 1 v bat _ bc v bat i ch _ term i bat < i ch _ term v bat > v bat _ re g v bat _ rch > v bat t0221 figure 13. system operation flowchart for the battery charger downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 11 programmable charging termination current the charging termination current i ch _ term can be programmed by connecting a resistor from term to g nd: 6 term ch_term 10 r i ? ? ? if the term pin is left open, the termination current level is set to 200 ma as the default. when the charging current drops to the termination current level, the device terminates charging and goes into a power- save mode. the charger remains in this mode until the battery voltage decreases to a level below the battery recharging voltage threshold (v bat _ rch ). consuming very low current in the power-save mode, the aat3620 minimizes battery drain when it is not charging. this feature is particularly useful in applications where the input supply level can fall below the battery charge. if the aat3620 input voltage drops, the device enters sleep mode and automatically resumes charging once the input supply has recovered from the fault condition. the term pin can also be used as a charging current monitor when the charging current voltage level = 1 a/v. status indicator (stat1/stat2) charging status output the aat3620 provides battery charger status using two status pins (stat1 and stat2). each of the two pins is internally connected to an n-channel open-drain mosfet. the status pin can indicate the conditions shown in table 6. the leds should be biased with as little current as necessary to create reasonable illumination. therefore, a ballast resistor should be placed between the led cathode and the stat pins. led current consumption adds to the overall thermal power budget for the device package, so keeping the led drive current to a minimum is recommended C 2 ma should be sufficient to drive most low-cost green or red leds. do not exceed 8 ma for driving an individual status led. the required ballast resistor values can be estimated using the following equation: led )led(f in ballsat i v v r ? ? example: ? k5.1 ma 2 v0.2 v0.5 r ballsat ? ? ? note: red led forward voltage (v f ) is typically 2.0 v @ 2 ma. protection circuitry charging safety timer (ct) while monitoring the charging cycle, the aat3620 utilizes a charging safety timer to help identify damaged cells and to ensure that the cell is charged safely: ? upon initiating a charging cycle, the aat3620 charges the cell at 10% of the programmed maximum charging until v bat > 2.6 v. ? if the cell voltage fails to reach the precondition threshold of 2.6 v (typical) before the safety timer expires, the cell is assumed to be damaged and the charging cycle terminates. ? if the cell voltage exceeds 2.6 v prior to the expiration of the timer, the charging cycle proceeds into fast charging. there are three time-out periods, as shown in table 7. table 6. led status indicator stat1 and stat2 conditions stat1 stat2 pre-charging on on fast-charging on off end-of-charging (charging complete) off on charging disabled off off sleep mode (v in < v in _ sleep ) off off no battery with charging enabled fla sh, 50% duty cycle flash, 50% duty cycle fault condition (battery 0 v) off off fault condition [battery ot (over-temperature) / ut (under-temperature)] off off fault condition (device ot) off off fault (pre-charging time out) off flash, 50% duty cycle fault (time out) off off downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 12 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without not ice ? 201904d table 7. summary for a 0.1 ? f ceramic capacitor used for the timing capacitor mode time trickle charging (tc) time-out 25 minutes trickle charging (tc) + constant-current (cc) mode time-out 2.2 hours constant-voltage (cv) mo de time-out 3 hours the aat3620 has a battery fault detector, which, when used in conjunction with a 0.1 ? f capacitor on the ct pin, outputs a 1 hz signal with 50% duty cycle at the stat2 pin in the event of a time-out while in trickle charging mode. the ct pin is driven by a constant-current source and provides a linear response to increase the timing capacitor value. thus, if the timing capacitor is doubled from the nominal 0.1 ? f value, the time-out periods are doubled. the ct pin should not be left floating or unterminated, as this would cause errors in the internal timing control circuit. the constant-current provided to charge the timing capacitor is very small, so this pin is susceptible to noise and changes in capacitance value. therefore, the timing capacitor should be physically located on the printed circuit board layout as close as possible to the ct pin. because the accuracy of the internal timer is dominated by the capacitance value, a ceramic capacitor with 10% tolerance or better is recommended. the x7r and x5r types of ceramic capacitors are good choices for this application. the aat3620 has the no-battery detection function, "no-bat". the ct pin capacitor (c ct ) sets up an internal clock to reset the no battery detector every 8 clock periods. the internal clock frequency is inversely proportional to the c ct : ct c hz nf 100 f ? ? the no-battery detection function detects when the charger toggles between charging termination and the recharging threshold in less than 8 clock periods. if this occurs for four consecutive times, the battery is considered disconnected. requiring four consecutive "no bat" cycles prevents a false indication when the battery connection is bounced. if the battery is disconnected while powered on, the recommended 0.1 ? f capacitor at ct pin creates a 1 hz internal clock to make the stat led blink at 1 hz, 50% duty cycle, to indicate no battery connected. to ensure that the charger cycles between charging termination and recharging in less than 8 clock periods, the bat pin capacitor cannot exceed 22 ? f for every 100 nf on the ct pin. for example, if c ct is 220 nf, the capacitor on the bat pin cannot exceed 47 ? f. if more capacitance is used on the bat pin, it takes longer than 8 clock periods to complete a charge termination/recharging cycle and the no-battery detection does not work. note that disabling the safety timer (ct pin grounded) on the aat3620 leads to a false "no bat" detection, and both stat pins go low after four consecutive charge termination/recharge cycles. over-voltage protection an over-voltage event is defined as a condition where the voltage on the bat pin exceeds the maximum battery charging voltage and is set by the over-voltage protection threshold (v bat _ ovp ). if an over-voltage condition occurs, the aat3620 charging control shuts down the device until the voltage on the bat pin drops below v bat _ ovp . the aat3620 resumes normal charging operation after the over-voltage condition is removed. during an over-voltage event, the stat leds report a system fault. over-temperature shutdown the aat3620 has a thermal protection control circuit which shuts down charging functions if the internal die temperature exceeds the preset thermal limit threshold. when the internal die temperature falls back below the thermal limit, normal operation resumes the previous charging state. battery temperature fault monitoring (ts) in the event of a battery over-temperature condition, the charging control turns off the internal pass device and reports a battery temperature fault on the stat pins. after the system recovers from a temperature fault, the device resumes charging operation. the aat3620 checks battery temperature before starting the charging cycle, as well as during all stages of charging. this is accomplished by monitoring the voltage at the ts pin. the internal battery temperature sensing system (figure 14) is comprised of two comparators that establish a voltage window for safe operation. the thresholds for the ts operating window are bounded by the v ts 1 and v ts 2 specifications. refer to the electrical characteristics in table 4: v ts 1 threshold = 0.30 ? v cc and the v ts 2 threshold = 0.60 ? v cc . this system is intended for use with negative temperature coefficient thermistors (ntc), which are typically integrated into the battery package. most of the commonly used ntc thermistors in battery packs are approximately 10 k ? at room temperature (25 c). if the battery gets too hot during charging due to an internal fault or excessive constant charging current, the thermistor heats up and reduces in value, pulling the ts pin voltage lower than the ts1 threshold, and the aat3620 stops charging until the condition is removed, when charging is resumed. to accurately set the ts voltage according to the temperature coefficient and the nominal value of the thermistor, two resistors can be used as shown in the example below. it is recommended to use ntc thermistors in the 10 k ? to 100 k ? range, with beta constant values in the 3000 to 5000 range. downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 13 ?? ? ? ?? ? ? ?? ? ? ? ? ? ?? ? ? ?? ? ? ? ? ?? ? ? ?? ? ? ? ? ? 1 cold ratio 1 r 1 hot ratio 1 r hot ratio 1 cold ratio 1 r r rt2 )cold(ntc )hot(ntc )cold(ntc )hot(ntc ?? ? ? ?? ? ? ?? ? ? ? ? ? ? ) cold (ntc ) cold (ntc r 2 rt r 2 rt cold ratio cold ratio 1 rt1 where: ratio cold = 0.60 (2% tolerance) ratio hot = 0.30 (2% tolerance) r ntc ( cold ) = thermistor resistance at cold (typically 0 c) r ntc ( hot ) = thermistor resistance at hot (typically 45 c) for a 10 k ? ntc thermistor with a beta of 3370: r ntc (0 ? c ) = 28.1 k ? r ntc (45 ? c ) = 4.91 k ? the calculation results are as follows: rt2 = 31.6 k ? rt1 = 9.92 k ? if the use of the ts pin function is not required by the system, it should be tied to vcc using a 10 k ? resistor. 0.6 v cc battery cold fault battery hot fault vcc ts pack 0.3 v cc battery rt1 rt2 r ntc v cc t0221 figure 14. aat3620 battery temperature sense circuit thermal considerations the actual maximum charging current is a function of charging adapter input voltage, the state of the battery charging at the moment of charging, the system supply current from the bat pin, the ambient temperature and the thermal impedance of the package. the maximum programmable current may not be achievable under all operating parameters. the aat3620 is offered in a tdfn33-14 package which can provide up to 2 w of power dissipation when properly bonded to a printed circuit board. the maximum thermal resistance is 50 c/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 design. the ambient temperature around the charger ic also has an effect on the thermal limits of a battery charging application. the maximum limits that can be expected for a given ambient condition can be estimated by the following considerations: 1. the maximum power dissipation for a given situation should be calculated: ja a )max(j d(max) t t p ? ? ? where: p d ( max ) = maximum power dissipation (w) ? ja = package thermal resistance (c/w) t j ( max ) = maximum device thermal shutdown temperature (c) [140 c] t a = ambient temperature (c) 2. the power dissipation for both the linear charging mode and the switching charger mode should be considered. the power dissipation for the switching charger can be calculated by the following equation: ? ? ? ? ?? pin qop cc_ch sw sw pin bat pin ls)on(ds bat hs)on(ds 2 cc_ch d(max) v i i f t v v v r v r i p ? ? ? ? ? ? ? ? ? ? ? where: p d ( max ) = total power dissipation by the device v pin = adapter input voltage v bat = battery voltage at the bat pin i ch _ cc = constant charging current programmed for the application i qop = quiescent current consumed by the ic for normal operation [5 ma] r ds ( on ) hs and r ds ( on ) ls = on-resistance of step-down high and low side mosfets 3. the power dissipation for the linear charging mode can be calculated by the following equation: ? ? qop pin cb_ch bat pin d(max) i v i v v p ? ? ? ? ? where: downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 14 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without not ice ? 201904d p d ( max ) = total power dissipation by the device v pin = input voltage v bat = battery voltage as seen at the bat pin i ch _ bc = battery conditioning charging current programmed for the application i qop = quiescent current consumed by the charger ic for normal operation [5 ma]. by substitution, the maximum charging current before reaching the thermal limit condition (thermal loop) can be derived. the maximum charging current is the key factor when designing battery charger applications: bat pin qop pin )max(d ch_bc(max) v v i v p i ? ? ? ? bat in qop pin ja a j ch(max) v v i v t t i ? ? ? ? ? ? in general, the worst condition is the greatest voltage drop across the charger ic, when battery voltage is charged up to the preconditioning voltage threshold and entering constant- current (cc) switching charging mode. example worst-case power dissipation the worst-case power dissipation can be calculated using the lowest battery voltage level when the charger enters cc charging mode and the charging current is set to 2 a: i ch _ cc = 2 a v pin =6 v r ds ( on ) hs = 0.3 ? r ds ( on ) ls = 0.25 ? t sw = 5 ? 10 -9 i qop = 0.005 a f sw = 1.5 ? 10 6 t a = 85 c ? ja = 50 c/w ?? ? ? ?? ?? ? ? ?? v6 a 005 .0 a2 10 5.1 10 5 v6 v8.2 v6 25.0 v8.2 3.0 a2 p 6 9 2 d(max) ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? w 213 .1 p d(max) ? )c( 213 .1 50 85 t j(max) ? ? ? ? )c(65. 145 t j(max) ? ? for the linear mode: i qop = 0.005 a v pin = 6 v v bat = 2 v i ch _ bc = 0.2 a ? ? a 005 .0 v6 a2.0 v2 v6 p d(max) ? ? ? ? ? w 83.0 p d(max) ? pcb layout guidance when laying out the pc board, follow the guidelines below to ensure proper operation of the aat3620: ? solder the exposed pad ep reliably to p g nd/a g nd and multilayer g nd. connect the exposed thermal pad to board ground plane and pins 2 and 3. include a large exposed copper pad under the package in the ground plane with vias to all board layers for thermal dissipation. ? keep the power traces, including g nd traces, the lx traces and the vin trace short, direct and wide to allow large current flow. make the l1 connection to the lx and cs pins as short as possible. use several via pads when routing between layers. ? connect the input capacitors (c1, c4, and c5) as close as possible to vpin (pin 1), vcc (pin 4) and g nd/p g nd (pins 2, 3) to get good power filtering. it is recommended to add a resistor r7 between vin and vcc to create a low-pass rc filter on vcc. ? connect the output capacitors c2, c6 and c7 and inductor l1 as close as possible, and do not route any signal lines under the inductor. ? keep the resistance of the trace from the load return to the p g nd (pin 2) to a minimum. this helps to minimize any error in dc regulation due to differences in the potential of the internal signal ground and the power ground. evaluation board description the aat3620 evaluation board is used to test the performance of the aat3620. an evaluation board schematic diagram is provided in figure 15. layer details for the evaluation board are shown in figure 16. the evaluation board has additional components for easy evaluation; the actual bill of materials required for the system is shown in table 8. package information package dimensions for the 14-pin tdfn33 package are shown in figure 17. tape and reel dimensions are shown in figure 18. downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 15 bat gnd t s tb1 vpin 1 pgnd 2 gnd 3 v cc 4 en 5 i s et 6 c t 7 s tat2 8 bat 12 s tat1 9 term 10 t s 11 cs 13 lx 14 ep aat3 6 20-tdfn33-14 u1 4.7 h l1 en jp1 s tat1 d1 s tat2 d2 100 k r4 4 9 . 9 k r3 10 k r1 10 k r2 v cc t s jp2 0.1 f c 3 2 k r5 2 k r 6 vin 0.1 f c 1 1 f c 5 vin tb2 gnd 10 f c 4 t s tp7 gnd tp 6 tp1 cs tp5 lx tp4 bat tp8 v cc tp2 100 r7 gnd tp3 22 f c 2 0.1 f c 7 0.1 f c6 vin tc94 figure 15. aat3620 evaluation board schematic table 8. aat3620 evaluation board bill of materials component description value footprint c4 capacitor, ceramic, x5r, 10 v, 20% 10 ? f 0805 c1, c3, c6, c7 capacitor, ceramic, 20%, 10 v, x5r 0.1 ? f 0603 c2 capacitor, ceramic, 20%, 10 v, x5r 22 ? f 1206 c5 capacitor, ceramic, 20%, 10 v, x5r 1 ? f 0603 l1 inductor, wurth, 7447789004 4.7 ? h 7 mm ? 7 mm r1, r2 resistor, 5% 10 k ? 0402 r5, r6 resistor, 5% 2 k ? 0402 r3 resistor, 1% 49.9 k ? 0402 r4 resistor, 1% 100 k ? 0402 r7 resistor, 1% 100 ? 0402 d1, d2 red and green smd 0402 (a) top layer (b) bottom layer tc95 figure 16. aat3620 evaluation board layer details downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 16 october 21, 2013 ? skyworks proprietary information ? pro ducts and product information are subject to change without not ice ? 201904d top view bottom view 3.000 0.050 index area 3.000 0.050 detail " a " 1. 6 50 0.050 2.500 0.050 0.203 ref 0.750 0.050 0.000 + 0.100 - 0.000 detail " a " s ide view 0.425 0.050 0.400 b sc 0.180 0.050 pin 1 indicator (optional) t00 6 0 all dimensions are in millimeters. figure 17. aat3620 14-pin tdfn package dimensions 1.50 0.10 1.10 0.00 0.30 0.05 1.75 0.10 5.50 0.05 2.00 0.05 12.00 0.30 4.00 0.00 8.00 0.10 3.30 0.10 pin 1 location all dimensions are in millimeters 3.30 0.10 t0059 figure 18. aat3620 tape and reel dimensions downloaded from: http:///
data sheet ? aat3620 single cell li+ switch mode battery charger skyworks solutions, inc. ? phone [ 781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201904d ? skyworks proprietary information ? products and product information are s ubject to change without notice ? oct ober 21, 2013 17 ordering information model name part marking (note 2) manufacturing part number (note 1) evaluation board part number aat3620 single cell li+ switch mode battery charger 6wxyy aat3620iwo-4.2-t1 aat3620iwo-4.2-evb note 1: xyy = assembly and date code. note 2: sample stock is generally held on part numbers listed in bold . copyright ? 2012-2013 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyw orks solutions, inc. (skyworks) products or services. these m aterials, including the information co ntained herein, are provided by skyworks as a service to its customers and may be used for info rmational purposes only by the customer. skyworks assumes no res ponsibility for errors or omissions in these materials or the information contained herein. skyworks may change its documentat ion, products, services, specific ations or product descriptions at any time, without notice. sk yworks makes no commitment to update the materials or information and shall have no responsib ility whatsoever for conflicts, incompatibilities, or other diff iculties arising from any future changes. no license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document . skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of skyworks products, information or mate rials, except as may be provided in skyworks terms and conditions of sale. the materials, products and information are pr ovided as is without warranty of any ki nd, whether express, implied, statutory, or otherwise, includin g fitness for a particular purpose or use, merchantability, performance, quality or non-infrin g ement of any intellectual property ri g ht; all such warranties are hereby expressly disclaimed. skyworks does not warra nt the accuracy or completeness of the information, text, g raphics or other items contained within these ma terials. skyworks shall not be liable for any dama g es, includin g but not limited to any special, indirect, incidental, statutory, or consequential dama g es, includin g without limitation, lost revenues or lost profits that may result from the use of the materials or information, whet her or not the recipient of mat erials has been advised of the possibility of such dama g e. skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the skyworks products could lead to personal injury, death, physical or environmental damage. skyworks customers using or selling skyworks products for use in such applications do so at their own risk and agree to fully indemnify skyworks for any damages resulting from such improper use or sale. customers are responsible for their products and applications us ing skyworks products, which ma y deviate from published specifi cations as a result of design defects, errors, or operation of products outside of published pa rameters or design specifications. customers sh ould include design and operating safeguards to minimize these and other risks. skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of skyworks products outsid e of stated published specifications or parameters. skyworks, the skyworks symbol, and breakthro ugh simplicity are trademarks or registered trademarks of skyworks solutions, inc ., in the united states and othe r countries. third-party brands and names are for identification purposes only, and are the proper ty of their respective owners. additional information, includ ing relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. downloaded from: http:///

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