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AAT2556 data sheet battery charger and step-down converter for portable applications 1 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 general description the AAT2556 is a member of skyworks' total power management ic (tpmic?) product family. it is a fully integrated 500ma battery charger plus a 250ma step- down converter. the input voltage range is 4v to 6.5v for the battery charger and 2.7v to 5.5v for the step-down converter, making it ideal for single-cell lithium-ion/poly- mer battery-powered applications. the battery charger is a complete constant current/ con- stant voltage linear charger. it offers an integrated pass device, reverse blocking protection, high current accu- racy and voltage regulation, charge status, and charge termination. the charging current is programmable via external resistor from 15ma to 500ma. in addition to standard features, the device offers over-voltage, cur- rent limit, and thermal protection. the step-down converter is a highly integrated converter operating at 1.5mhz of switching frequency, minimizing the size of external components while keeping switching losses low. it has independent input and enable pins. the output voltage ranges from 0.6v to the input volt- age. the feedback and control deliver excellent load regulation and transient response with a small output inductor and capacitor. the AAT2556 is available in a pb-free, thermally- enhanced tdfn33-12 package and is rated over the -40c to +85c temperature range. features battery charger: ? input voltage range: 4v to 6.5v ? programmable charging current up to 500ma ? highly integrated battery charger ? charging device ? reverse blocking diode step-down converter: ? input voltage range: 2.7v to 5.5v ? output voltage range: 0.6v to v in ? 250ma output current ? up to 96% efficiency ? 30 a quiescent current ? 1.5mhz switching frequency ? 100 s start-up time short-circuit, over-temperature, and current limit protection tdfn33-12 package -40c to +85c temperature range applications bluetooth? headsets cellular phones handheld instruments mp3 and portable music players pdas and handheld computers portable media players typical application c batt - adp iset gnd bat batt + adapter / usb input stat en_bat enable r set vin en_buck l= 3.3h fb lx r fb2 r fb1 c out v out system battery pack downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 2 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 pin descriptions pin # symbol function 1 fb feedback input. this pin must be connected directly to an external resistor divider. nominal voltage is 0.6v. 2, 8, 10 gnd ground. 3 en_buck enable pin for the step-down converter. when connected to logic low, the step-down converter is disabled and it consumes less than 1 a of current. when connected to logic high, it resumes normal operation. 4 en_bat enable pin for the battery charger. when internally pulled down, the battery charger is disabled and it con- sumes less than 1 a of current. when connected to logic high, it resumes normal operation. 5 iset charge current set point. connect a resistor from this pin to ground. refer to typical curves for resistor selection. 6 bat battery charging and sensing. 7 stat charge status input. open drain status input. 9 adp input for usb/adapter charger. 11 lx output of the step-down converter. connect the inductor to this pin. internally, it is connected to the drain of both high- and low-side mosfets. 12 vin input voltage for the step-down converter. ep exposed paddle (bottom): connect to ground directly beneath the package. pin configuration tdfn33-12 (top view) fb gnd en_buck 1 en_bat iset bat vinlx gnd adp gnd sta t 2 3 4 5 6 12 11 10 9 8 7 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 3 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at conditions 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. absolute maximum ratings 1 symbol description value units v in input voltage to gnd 6.0 v v adp adapter voltage to gnd -0.3 to 7.5 v v lx lx to gnd -0.3 to v in + 0.3 v v fb fb to gnd -0.3 to v in + 0.3 v v en en_bat and en_buck to gnd -0.3 to 6.0 v v x bat, iset and stat to gnd -0.3 to v adp + 0.3 v t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c thermal information symbol description value units p d maximum power dissipation 2.0 w ? ja thermal resistance 2 50 c/w downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 4 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 1. the AAT2556 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls. 2. output voltage tolerance is independent of feedback resistor network accuracy. electrical characteristics 1 v in = 3.6v; t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units step-down converter v in input voltage 2.7 5.5 v v uvlo uvlo threshold v in rising 2.7 v hysteresis 200 mv v in falling 1.8 v v out output voltage tolerance 2 i out = 0 to 250ma, v in = 2.7v to 5.5v -3.0 3.0 % v out output voltage range 0.6 v in v i q quiescent current no load 30 a i shdn shutdown current en = gnd 1.0 a i lim p-channel current limit 600 ma r ds(on)h high-side switch on resistance 0.59 ? r ds(on)l low-side switch on resistance 0.42 ? i lxleak lx leakage current v in = 5.5v, v lx = 0 to v in 1.0 a ? v linereg / ? v in line regulation v in = 2.7v to 5.5v 0.2 %/v v fb feedback threshold voltage accuracy v in = 3.6v 0.591 0.600 0.609 v i fb fb leakage current v out = 1.0v 0.2 a f osc oscillator frequency 1.5 mhz t s startup time from enable to output regulation 100 s t sd over-temperature shutdown threshold 140 c t hys over-temperature shutdown hysteresis 15 c v en(l) enable threshold low 0.6 v v en(h) enable threshold high 1.4 v i en input low current v in = v en = 5.5v -1.0 1.0 a downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 5 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 1. the AAT2556 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. electrical characteristics 1 v adp = 5v; t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units battery chargeroperation 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 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 15 500 ma ? i ch /i ch charge current regulation tolerance 10 % v set iset pin voltage 2v 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 stat output low voltage stat pin sinks 4ma 0.4 v i stat stat pin current sink capability 8m a v ovp over-voltage protection threshold 4.4 v i tk /i chg pre-charge current i ch = 100ma 10 % i term /i chg charge termination threshold current 10 % downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 6 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C step-down converter efficiency vs. load (v out = 1.8v; l = 3.3h) output current (ma) efficiency (%) 40 50 60 70 80 90 100 0.1 1 10 100 1000 v in = 3.6v v in = 2.7v v in = 4.2v v in = 5.0v v in = 5.5v dc load regulation (v out = 1.8v; l = 3.3h) output current (ma) output error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 v in = 4.2v v in = 3.6v v in = 2.7v v in = 5.5v v in = 5.0v efficiency vs. load (v out = 1.2v; l = 1.5h) output current (ma) efficiency (%) 30 40 50 60 70 80 90 100 0.1 1 10 100 1000 v in = 3.6v v in = 2.7v v in = 5.5v v in = 4.2v v in = 5.0v dc load regulation (v out = 1.2v; l = 1.5h) output current (ma) output error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 v in = 5.0v v in = 5.5v v in = 2.7v v in = 4.2v v in = 3.6v soft start (v in = 3.6v; v out = 1.8v; i out = 250ma; c ff = 100pf) enable and output voltage (top) (v) inductor current (bottom) (a) time (100s/div) -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 -0.2-0.4 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 v en v o i l line regulation (v out = 1.8v) input voltage (v) accuracy (%) -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 i out = 250ma i out = 10ma i out = 0ma i out = 50ma i out = 150ma downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 7 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C step-down converter output voltage error vs. temperature (v in = 3.6v; v out = 1.8v; i out = 250ma) temperature ( c) output error (%) -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 -40 -20 0 20 40 60 80 100 switching frequency variation vs. temperature (v in = 3.6v; v out = 1.8v) temperature ( c) variation (%) -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 -40 -20 0 20 40 60 80 100 frequency variation vs. input voltage (v out = 1.8v) input voltage (v) frequency variation (%) -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 no load quiescent current vs. input voltage input voltage (v) supply current (a) 10 15 20 25 30 35 40 45 50 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 85 c 25 c -40 c p-channel r ds(on) vs. input voltage input voltage (v) r ds(on)h (m ) 300 400 500 600 700 800 900 1000 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 120 c 100 c 85 c 25 c n-channel r ds(on) vs. input voltage input voltage (v) r ds(on)l (m ) 300 350 400 450 500 550 600 650 700 750 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 120 c 100 c 85 c 25 c downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 8 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C step-down converter load transient response (10ma to 250ma; v in = 3.6v; v out = 1.8v; c out = 4.7f; c ff = 100pf) output voltage (top) (v) load and inductor current (bottom) (200ma/div) time (25s/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 v o i lx i o load transient response (10ma to 250ma; v in = 3.6v; v out = 1.8v; c out = 4.7f) output voltage (top) (v) load and inductor current (bottom) (200ma/div) time (25s/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 v o i lx i o line response (v out = 1.8v @ 250ma; c ff = 100pf) output voltage (top) (v) input voltage (bottom) (v) time (25s/div) 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 v o v in output ripple (v in = 3.6v; v out = 1.8v; i out = 1ma) output voltage (ac coupled) (top) (mv) inductor current (bottom) (a) time (2s/div) -120 -100 -80 -60 -40 -20 0 20 40 -0.01 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 v o i l output ripple (v in = 3.6v; v out = 1.8v; i out = 250ma) output voltage (ac coupled) (top) (v) inductor current (bottom) (a) time (200ns/div) -120 -100 -80 -60 -40 -20 0 20 40 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 v o i l downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 9 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C battery charger r set (k ) i ch (ma) constant charging current vs. set resistor values 1 10 100 1000 1 10 100 1000 charging current vs. battery voltage (v adp = 5v) 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 = 8.06k r set = 5.36k r set = 3.24k r set = 16.2k r set = 31.6k end of charge battery voltage vs. supply voltage v adp (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 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 constant charging current vs. supply voltage (r set = 8.06k ) v adp (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 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 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 10 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C battery charger 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 preconditioning threshold voltage vs. temperature (r set = 8.06k ) 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 preconditioning charge current vs. temperature (r set = 8.06k ) 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 charge current vs. supply voltage v adp (v) i trickle (ma) 0 10 20 30 40 50 60 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4 r set = 8.06k r set = 5.36k r set = 3.24k r set = 16.2k r set = 31.6k 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 sleep mode current vs. supply voltage (r set = 8.06k ) v adp (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 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 11 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 typical characteristics C battery charger v en(h) vs. supply voltage (r set = 8.06k ) v adp (v) v en(h) (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 v en(l) vs. supply voltage (r set = 8.06k ) v adp (v) v en(l) (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 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 12 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 functional description the AAT2556 is a high performance power system com- prised of a 500ma lithium-ion/polymer battery charger and a 250ma step-down converter. the battery charger is designed for single-cell lithium-ion/ polymer batteries using a constant current and constant voltage algorithm. the battery charger operates from the adapter/usb input voltage range from 4v to 6.5v. the adapter/usb charging current level can be programmed up to 500ma for rapid charging applications. a status monitor output pin is provided to indicate the battery charge state by directly driving one external led. internal device temperature and charging state are fully moni- tored 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 sys- tem, and the battery under charge. other features include an integrated reverse blocking diode and sense resistor. the step-down converter operates with an input voltage of 2.7v to 5.5v. the switching frequency is 1.5mhz, minimizing the size of the inductor. under light load con- ditions, the device enters power-saving mode; the switching frequency is reduced, and the converter con- sumes 30 a of current, making it ideal for battery-oper- ated applications. the output voltage is programmable from v in to as low as 0.6v. power devices are sized for 250ma current capability while maintaining over 90% efficiency at full load. light load efficiency is maintained at greater than 80% down to 1ma of load current. a high-dc gain error amplifier with internal compensation controls the output. it provides excellent transient response and load/line regulation. under-voltage lockout the AAT2556 has internal circuits for uvlo and power on reset features. if the adp supply voltage drops below the uvlo threshold, the battery charger will suspend charg- ing and shut down. when power is reapplied to the adp pin or the uvlo condition recovers, the system charge control will automatically resume charging in the appro- priate mode for the condition of the battery. if the input voltage of the step-down converter drops below uvlo, the internal circuit will shut down. protection circuitry over-voltage protection an over-voltage protection event is defined as a condition where the voltage on the bat pin exceeds the over-volt- age protection threshold (v ovp ). if this over-voltage condi- tion occurs, the charger control circuitry will shut down the device. the charger will resume normal charging operation after the over-voltage condition is removed. functional block diagram charge control reverse blocking constant current bat uvlo over- temperature protection stat gnd + - + - iset adp en_ba t vin lx logic dh dl + - v ref v ref fb input en_buck downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 13 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 current limit, over-temperature protection for overload conditions, the peak input current is limited at the step-down converter. as load impedance decreas- es and the output voltage falls closer to zero, more power is dissipated internally, which causes the internal die temperature to rise. in this case, the thermal protec- tion circuit completely disables switching, which protects the device from damage. the battery charger has a thermal protection circuit which will shut down charging functions when the internal die temperature exceeds the preset thermal limit threshold. once the internal die temperature falls below the thermal limit, normal charging operation will resume. control loop the AAT2556 contains a compact, current mode step- down dc/dc controller. the current through the p-channel mosfet (high side) is sensed for current loop control, as well as short-circuit and overload protection. a fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. the peak current mode loop appears as a voltage- programmed current source in parallel with the output capacitor. the output of the voltage error amplifier pro- grams the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. internal loop compensation terminates the transconductance voltage error amplifier output. the error amplifier reference is fixed at 0.6v. battery charging operation battery charging commences only after checking several conditions in order to maintain a safe charging environ- ment. the input supply (adp) must be above the mini- mum operating voltage (uvlo) and the enable pin must be high (internally pulled down). when the battery is connected to the bat pin, the charger checks the condi- tion of the battery and determines which charging mode to apply. if the battery voltage is below v min , the charger begins battery pre-conditioning by charging at 10% of the programmed constant current; e.g., if the pro- grammed current is 150ma, then the pre-conditioning current (trickle charge) is 15ma. pre-conditioning is purely a safety precaution for a deeply discharged cell and will also reduce the power dissipation in the internal series pass mosfet when the input-output voltage dif- ferential is at its highest. pre-conditioning continues until the battery voltage reaches v min . at this point, the charger begins constant- current charging. the current level for this mode is pro- grammed using a single resistor from the iset pin to ground. programmed current can be set from a mini- mum 15ma up to a maximum of 500ma. constant cur- rent charging will continue until the battery voltage reaches the voltage regulation point, v bat . when the battery voltage reaches v bat , the battery charger begins constant voltage mode. the regulation voltage is factory programmed to a nominal 4.2v (0.5%) and will con- tinue charging until the charging current has reduced to 10% of the programmed current. after the charge cycle is complete, the pass device turns off and the device automatically goes into a power-sav- ing sleep mode. during this time, the series pass device will block current in both directions, preventing the bat- tery from discharging through the ic. the battery charger will remain in sleep mode, even if the charger source is disconnected, until one of the fol- lowing events occurs: the battery terminal voltage drops below the v rch threshold; the charger en pin is recycled; or the charging source is reconnected. in all cases, the charger will monitor all parameters and resume charging in the most appropriate mode. constant current charge phase constant voltage charge phase preconditioning trickle charge phase charge complete voltage constant current mode voltage threshold regulated currenttrickle charge and termination threshold i = cc / 10 i = max cc figure 1: current vs. voltage profile during charging phases. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 14 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 battery charging system operation flow chart power on reset power input voltage v adp > v uvlo fault conditions monitoring ov, ot preconditioning test v min > v bat current phase test v adp > v bat voltage phase test i bat > i term no 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 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 15 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 application informationsoft start / enable the en_bat pin is internally pulled down. when pulled to a logic high level, the battery charger is enabled. when left open or pulled to a logic low level, the battery charger is shut down and forced into the sleep state. charging will be halted regardless of the battery voltage or charging state. when it is re-enabled, the charge con- trol circuit will automatically reset and resume charging functions with the appropriate charging mode based on the battery charge state and measured cell voltage from the bat pin. the step-down converter features a soft start that limits the inrush current and eliminates output voltage over- shoot during startup. the circuit is designed to increase the inductor current limit in discrete steps when the input voltage or enable input is applied. typical start up time is 100 s. pulling en_buck to logic low forces the converter in a low power, non-switching state, and it consumes less than 1 a of quiescent current. connecting it to logic high enables the converter and resumes normal operation. adapter or usb power input constant current charge levels up to 500ma may be programmed by the user when powered from a sufficient input power source. the battery charger 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 connected between iset and ground. refer to table 1 for recommended r set val- ues for a desired constant current charge level. 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 trickle charge current, is domi- nated by the tolerance of the set resistor used. for this reason, a 1% tolerance metal film resistor is recom- mended for the set resistor function. fast charge con- stant current levels from 15ma to 500ma may be set by selecting the appropriate resistor value from table 1. normal i charge (ma) set resistor value r2 (k ? ) 500 3.24 400 4.12 300 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 table 1: r set values. r set (k ) i ch (ma) 1 10 100 1000 1 10 100 1000 figure 2: constant charging current vs. set resistor values. charge status output the AAT2556 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 exter- nal led. the status pin can indicate several conditions, as shown in table 2. event description status no battery charging activity off battery charging via adapter or usb port on charging completed off table 2: led status indicator. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 16 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 the led should be biased with as little current as neces-sary to create reasonable illumination; therefore, a bal- last 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 pack- age, 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 estimated using the following formulas: v adp - v f(led) r 1 = i led example: 5.5v - 2.0 v r 1 = = 1.75k 2ma note: red led forward voltage (v f ) is typically 2.0v @ 2ma.thermal considerations the AAT2556 is offered in a tdfn33-12 package which can provide up to 2w of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50c/w. many consider- ations 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 gener- ating devices in a given application design. the ambient temperature around the ic will also have an effect on the thermal limits of a battery charging application. the maximum limits that can be expected for a given ambi- ent condition can be estimated by the following discus- sion. first, the maximum power dissipation for a given situa- tion should be calculated: (t j(max) - t a ) p d(max) = ja 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 dis- sipation and ambient temperature of the AAT2556. t a ( c) p d(max) (mw) 0 500 1000 1500 2000 2500 3000 0 20 40 60 80 100 120 figure 3: maximum power dissipation. next, the power dissipation of the battery charger can be calculated by the following equation: p d = [(v adp - v bat ) i ch + (v adp i op )] where:p d = total power dissipation by the device v adp = adp/usb 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 cur- rent before reaching the thermal limit condition (thermal cycling). the maximum charge current is the key factor when designing battery charger applications. (p d(max) - v in i op ) v in - v bat i ch(max) = (t j(max) - t a ) ja v in - v bat i ch(max) = - v in i op in general, the worst condition is the greatest voltage drop across the ic, when battery voltage is charged up to the preconditioning voltage threshold. figure 4 shows the maximum charge current in different ambient tem- peratures. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 17 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 v in (v) i cc(max) (ma) 0 100 200 300 400 500 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5 6.75 t a = 85c t a = 60c figure 4: maximum charging current before thermal cycling becomes active. there are three types of losses associated with the step- down converter: switching losses, conduction losses, and quiescent current losses. conduction losses are associ- ated with the r ds(on) characteristics of the power output switching devices. switching losses are dominated by the gate charge of the power output switching devices. at full load, assuming continuous conduction mode (ccm), a simplified form of the losses is given by: p total i o 2 (r dson(h) v o + r dson(l) [v in - v o ]) v in = + (t sw f s i o + i q ) v in i q is the step-down converter quiescent current. the term t sw is used to estimate the full load step-down con- verter switching losses. for the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: p total = i o 2 r dson(h) + i q v in since r ds(on) , quiescent current, and switching losses all vary with input voltage, the total losses should be inves- tigated over the complete input voltage range. given the total losses, the maximum junction tempera- ture can be derived from the ? ja for the tdfn33-12 package which is 50c/w. t j(max) = p total ja + t amb capacitor selectionbattery charger input capacitor (c1) in general, it is good design practice to place a decou- pling capacitor between the adp pin and gnd. an input capacitor in the range of 1 f to 22 f 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 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 10 f 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. step-down converter input capacitor (c3) select a 4.7 f to 10 f x7r or x5r ceramic capacitor for the input. to estimate the required input capacitor size, determine the acceptable input ripple level (v pp ) and solve for c in . the calculated value varies with input voltage and is a maximum when v in is double the output voltage. ?? 1 - ?? v o v in c in = v o v in ?? - esr f s ?? v pp i o ?? 1 - = for v in = 2 v o ?? v o v in v o v in 14 c in(min) = 1 ?? - esr 4 f s ?? v pp i o always examine the ceramic capacitor dc voltage coef- ficient characteristics when selecting the proper value. for example, the capacitance of a 10 f, 6.3v, x5r ceramic capacitor with 5.0v dc applied is actually about 6 f. the maximum input capacitor rms current is: ?? 1 - = d (1 - d) = 0.5 2 = ?? v o v in v o v in 12 downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 18 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 the input capacitor rms ripple current varies with the input and output voltage and will always be less than or equal to half of the total dc load current. ?? i rms = i o 1 - ?? v o v in v o v in for v in = 2 v o i o rms(max) i 2 = the term ?? 1 - ?? v o v in v o v in appears in both the input voltage ripple and input capacitor rms current equations and is a maximum when v o is twice v in . this is why the input voltage ripple and the input capacitor rms current ripple are a maximum at 50% duty cycle. the input capacitor provides a low impedance loop for the edges of pulsed current drawn by the step-down con- verter. low esr/esl x7r and x5r ceramic capacitors are ideal for this function. to minimize stray inductance, the capacitor should be placed as closely as possible to the ic. this keeps the high frequency content of the input current localized, minimizing emi and input voltage ripple. the proper placement of the input capacitor (c3) can be seen in the evaluation board layout in figure 6. a laboratory test set-up typically consists of two long wires running from the bench power supply to the evalu- ation board input voltage pins. the inductance of these wires, along with the low-esr ceramic input capacitor, can create a high q network that may affect converter performance. this problem often becomes apparent in the form of excessive ringing in the output voltage dur- ing load transients. errors in the loop phase and gain measurements can also result. since the inductance of a short pcb trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. in applications where the input power source lead induc- tance cannot be reduced to a level that does not affect the converter performance, a high esr tantalum or alu- minum electrolytic capacitor should be placed in parallel with the low esr, esl bypass ceramic capacitor. this dampens the high q network and stabilizes the system. battery charger output capacitor (c2) the AAT2556 only requires a 1 f ceramic capacitor on the bat pin to maintain circuit stability. this value should be increased to 10 f or more if the battery connection is made any distance from the charger output. if the AAT2556 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 10 f may be required to prevent the device from cycling on and off when no battery is present. step-down converter output capacitor (c4) the output capacitor limits the output ripple and pro- vides holdup during large load transitions. a 4.7 f to 10 f x5r or x7r ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the esr and esl charac- teristics necessary for low output ripple. for enhanced transient response and low temperature operation appli- cations, a 10 f (x5r, x7r) ceramic capacitor is recom- mended to stabilize extreme pulsed load conditions. the output voltage droop due to a load transient is dom- inated by the capacitance of the ceramic output capacitor. during a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. the relationship of the output volt- age droop during the three switching cycles to the output capacitance can be estimated by: c out = 3 i load v droop f s once the average inductor current increases to the dc load level, the output voltage recovers. the above equa- tion establishes a limit on the minimum value for the output capacitor with respect to load transients. the internal voltage loop compensation also limits the minimum output capacitor value to 4.7 f. this is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. increased output capac- itance will reduce the crossover frequency with greater phase margin. the maximum output capacitor rms ripple current is given by: 1 23 v out (v in(max) - v out ) rms(max) i l f s v in(max) = dissipation due to the rms current in the ceramic output capacitor esr is typically minimal, resulting in less than a few degrees rise in hot-spot temperature. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 19 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 inductor selection the step-down converter uses peak current mode con- trol with slope compensation to maintain stability for duty cycles greater than 50%. the output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. the internal slope compensation for the AAT2556 is 0.45a/ sec. this equates to a slope compensation that is 75% of the inductor current down slope for a 1.8v output and 3.0 h inductor. 0.75 ? v o m = = = 0.45 l 0.75 ? 1.8v 3.0h a sec 0.75 ? v o l = = 1.67 ? v o = 1.67 ? 3.0v = 5.0h m 0.75 ? v o 0.45a sec a sec a a sec for most designs, the step-down converter operates with an inductor value of 1 h to 4.7 h. table 3 displays inductor values for the AAT2556 with different output voltage options. manufacturers specifications list both the inductor dc current rating, which is a thermal limitation, and the peak current rating, which is determined by the satura- tion characteristics. the inductor should not show any appreciable saturation under normal load conditions. some inductors may meet the peak and average current ratings yet result in excessive losses due to a high dcr. always consider the losses associated with the dcr and its effect on the total converter efficiency when selecting an inductor. the 3.0 h cdrh2d09 series inductor selected from sumida has a 150m ? dcr and a 470ma dc current rat- ing. at full load, the inductor dc loss is 9.375mw which gives a 2.08% loss in efficiency for a 250ma, 1.8v out- put. output voltage (v) l1 ( h) 1.0 1.5 1.2 2.2 1.5 2.7 1.8 3.0/3.3 2.5 3.9/4.2 3.0 4.7 3.3 5.6 table 3: inductor values. adjustable output resistor selection resistors r3 and r4 of figure 5 program the output to regulate at a voltage higher than 0.6v. to limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the suggested value for r4 is 59k ? . decreased resistor values are nec- essary to maintain noise immunity on the fb pin, result- ing in increased quiescent current. table 4 summarizes the resistor values for various output voltages. ???? r3 = -1 r4 = - 1 59k = 267k v out v ref ???? 3.3v 0.6v with enhanced transient response for extreme pulsed load application, an external feed-forward capacitor (c5 in figure 5) can be added. v out (v) r4 = 59k ? r4 = 221k ? r3 (k ? ) r3 (k ? ) 0.8 19.6 75 0.9 29.4 113 1.0 39.2 150 1.1 49.9 187 1.2 59.0 221 1.3 68.1 261 1.4 78.7 301 1.5 88.7 332 1.8 118 442 1.85 124 464 2.0 137 523 2.5 187 715 3.3 267 1000 table 4: adjustable resistor values for step-down converter. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 20 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 printed circuit boardlayout considerations for the best results, it is recommended to physically place the battery pack as close as possible to the AAT2556 bat pin. to minimize voltage drops on the pcb, keep the high current carrying traces adequately wide. refer to the AAT2556 evaluation board for a good layout example (see figures 6 and 7). the following guidelines should be used to help ensure a proper layout. 1. the input capacitors (c1, c3) should connect as closely as possible to adp (pin 9) and vin (pin 12). 2. c4 and l1 should be connected as closely as possi- ble. the connection of l1 to the lx pin should be as short as possible. do not make the node small by using narrow trace. the trace should be kept wide, direct, and short. 3. the feedback pin (pin 1) should be separate from any power trace and connect as closely as possible to the load point. sensing along a high-current load trace will degrade dc load regulation. feedback resistors should be placed as closely as possible to the fb pin (pin 1) to minimize the length of the high impedance feedback trace. if possible, they should also be placed away from the lx (switching node) and inductor to improve noise immunity. 4. the resistance of the trace from the load return to pgnd (pin 10) and gnd (pin 2) should be kept to a minimum. this will help to minimize any error in dc regulation due to differences in the potential of the internal signal ground and the power ground. 5. a high density, small footprint layout can be achieved using an inexpensive, miniature, non-shielded, high dcr inductor. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 21 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 red led d1 1k r1 c110f c2 2.2f adp r28.06k jp10 bat 1 2 3 enable_buck jp3 3h l1 100pf c5 c44.7f vout 118k r3 59k r4 1 2 3 buck input jp4 1 2 enable_bat jp2 4.7f c3 vin iset 5 fb 1 bat 6 gnd 8 gnd 2 en _ buck 3 stat 7 en _ bat 4 adp 9 gnd 10 lx 11 vin 12 AAT2556 u1 vout figure 5: AAT2556 evaluation board schematic. figure 6: AAT2556 evaluation board figure 7: AAT2556 evaluation board top side layout. bottom side layout. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 22 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 component part number description manufacturer u1 AAT2556iwp-t1 battery charger and step-down converter for portable applications; tdfn33-12 package skyworks c1 ecj-1vb0j106m cer 10 f 10v 20% x5r 0603 panasonic - ecg c2 grm185b30j225ke25d cer 2.2 f 6.3v 10% x7r 0603 murata c3, c4 grm188r60j475ke19b cer 4.7 f 6.3v 10% x7r 0603 murata c5 grm1886r1h101jz01j cer 100pf 50v 5% r2h 0603 murata l1 cdrh2d09-3r0 shielded smd, 3.0 h, 150m ? , 3x3x1mm sumida r1 chip resistor 1k ? , 5%, 1/4w; 0603 vishay r2 chip resistor 8.06k ? , 1%, 1/4w; 0603 vishay r3 chip resistor 118k ? , 1%, 1/4w; 0603 vishay r4 chip resistor 59k ? , 1%, 1/4w; 0603 vishay jp1 chip resistor 0 ? , 5%, 1/4w; 0603 vishay jp2, jp3, jp4 prpn401paen connecting header, 2mm zip sullins electronics d1 cmd15-21src/tr8 red led; 1206 chicago miniature lamp table 5: AAT2556 evaluation board component listing. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 23 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 step-down converter design examplespecifications v o = 1.8v @ 250ma, pulsed load ? i load = 200ma v in = 2.7v to 4.2v (3.6v nominal) f s = 1.5mhz t amb = 85c 1.8v output inductor l1 = 1.67 ? v o2 = 1.67 ? 1.8v = 3h sec a sec a (use 3.0 h; see table 3) for sumida inductor cdrh2d09-3r0, 3.0 h, dcr = 150m ? . v o v o 1.8 v 1.8v i l1 = ? 1 - = ? 1 - = 228m a l1 ? f s v in 3.0h ? 1.5mhz 4.2v i pkl1 = i o + i l1 = 250ma + 114ma = 364ma 2 p l1 = i o 2 ? dcr = 250ma 2 ? 150m = 9.375mw ?? ?? ?? ?? 1.8v output capacitorv droop = 0.1v 1 23 1 1.8v (4.2v - 1.8v) 3.0h 1.5mhz 4.2v 23 rms i l1 f s v in(max) = 3 i load v droop f s 3 0.2a 0.1v 1.5mhz c out = = = 4f; use 4.7f = 66marms (v o ) (v in(max) - v o ) = p esr = esr i rms 2 = 5m (66ma) 2 = 21.8w downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 24 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 input capacitorinput ripple v pp = 25mv c in = = = 1.38f (use 4.7f ) 1 ?? - esr 4 f s ?? v pp i o 1 ?? - 5m 4 1.5mhz ?? 25mv 0.2a i o rms ip = esr i rms 2 = 5m (0.1a) 2 = 0.05mw 2 = = 0.1arms AAT2556 losses p total + (t sw f s i o + i q ) v in i o 2 (r dson(h) v o + r dson(l) [v in -v o ] ) v in = = + ( 5ns 1.5mhz 0.2a + 30a ) 4.2v = 26.14mw 0.2 2 (0.59 1.8v + 0.42 [4.2v - 1.8v]) 4.2v t j( max ) = t amb + j a p l oss = 85 c + ( 50 c/w ) 26.14mw = 86.3 c downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 25 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 1. for reduced quiescent current, r4 = 221kw. 2. r4 is opened, r3 is shorted. output voltage v out (v) r4 = 59k ? r3 (k ? ) r4 = 221k ? 1 r3 (k ? ) l1 ( h) 0.6 2 1.5 0.8 19.6 75 1.5 0.9 29.4 113 1.5 1.0 39.2 150 1.5 1.1 49.9 187 1.5 1.2 59.0 221 1.5 1.3 68.1 261 1.5 1.4 78.7 301 2.2 1.5 88.7 332 2.7 1.8 118 442 3.0/3.3 1.85 124 464 3.0/3.3 2.0 137 523 3.0/3.3 2.5 187 715 3.9/4.2 3.3 267 1000 5.6 table 6: step-down converter component values. manufacturer part number inductance ( h) max dc current (ma) dcr (m ? ) size (mm) lxwxh type sumida cdrh2d09-1r5 1.5 730 88 3.0x3.0x1.0 shielded sumida cdrh2d09-2r2 2.2 600 115 3.0x3.0x1.0 shielded sumida cdrh2d09-2r5 2.5 530 135 3.0x3.0x1.0 shielded sumida cdrh2d09-3r0 3 470 150 3.0x3.0x1.0 shielded sumida cdrh2d09-3r9 3.9 450 180 3.0x3.0x1.0 shielded sumida cdrh2d09-4r7 4.7 410 230 3.0x3.0x1.0 shielded sumida cdrh2d09-5r6 5.6 370 260 3.0x3.0x1.0 shielded sumida cdrh2d11-1r5 1.5 900 54 3.2x3.2x1.2 shielded sumida cdrh2d11-2r2 2.2 780 78 3.2x3.2x1.2 shielded sumida cdrh2d11-3r3 3.3 600 98 3.2x3.2x1.2 shielded sumida cdrh2d11-4r7 4.7 500 135 3.2x3.2x1.2 shielded taiyo yuden nr3010 1.5 1200 80 3.0x3.0x1.0 shielded taiyo yuden nr3010 2.2 1100 95 3.0x3.0x1.0 shielded taiyo yuden nr3010 3.3 870 140 3.0x3.0x1.0 shielded taiyo yuden nr3010 4.7 750 190 3.0x3.0x1.0 shielded fdk mipwt3226d-1r5 1.5 1200 90 3.2x2.6x0.8 chip shielded fdk mipwt3226d-2r2 2.2 1100 100 3.2x2.6x0.8 chip shielded fdk mipwt3226d-3r0 3 1000 120 3.2x2.6x0.8 chip shielded fdk mipwt3226d-4r2 4.2 900 140 3.2x2.6x0.8 chip shielded table 7: suggested inductors and suppliers. manufacturer part number value ( f) voltage rating temp. co. case size murata grm118r60j475ke19b 4.7 6.3 x5r 0603 murata grm188r60j106me47d 10 6.3 x5r 0603 table 8: surface mount capacitors. downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 26 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . ordering information package marking 1 part number (tape and reel) 2 tdfn33-12 spxyy AAT2556iwp-ca-t1 skyworks green? products are compliant with all applicable legislation and are halogen-free. for additional information, refer to skyworks de?ition of green , document number sq04-0074. legend voltage code adjustable (0.6v) a 0.9 b 1.2 e 1.5 g 1.8 i 1.9 y 2.5 n 2.6 o 2.7 p 2.8 q 2.85 r 2.9 s3.0 t 3.3 w 4.2 c downloaded from: http:///
AAT2556 data sheet battery charger and step-down converter for portable applications 27 skyworks solutions, inc. phone [781] 376-3000 fax [781] 376-3100 sales@skyworksinc.com www.skyworksinc.com 202177b skyworks proprietary information products and product information are subject to change without notice. march 19, 2013 copyright ? 2012, 2013 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyworks solutions, inc. (skyworks) products or services. these materials, including the information contained herein, are provided by sky works as a service to its customers and may be used for informational purposes only by the customer. skyworks assumes no responsibility fo r errors or omissions in these materials or the information contained herein. sky- works may change its documentation, products, services, speci ? cations or product descriptions at any time, without notice. skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for con ? icts, incompatibilities, or other dif ? culties 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 informatio n provided here- under, including the sale, distribution, reproduction or use of skyworks products, information or materials, except as may be provided in skyworks terms and conditions of sale. the materials, products and information are provided as is without warranty of any kind, whether express, implied, statutory, or otherwise, including fitness for a particular purpose or use, merchantability, performance, quality or non-infringement of any intellectual property right; all such warranti es are hereby expressly disclaimed. skyworks does not warrant the accuracy or completeness of the information, text, graphics or other items contained within these materials. skyworks shall not be liable for any damages, in- cluding but not limited to any special, indirect, incidental, statutory, or consequential damages, including without limitation, lost revenues or lost profits that may result from the use of the materials or information, whether or not the recipient of materials has been advised of the possibility of such damage. 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 en- vironmental 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 using skyworks products, which may deviate from published speci ? cations as a result of design defects, errors, or operation of products outside of pub- lished parameters or design speci ? cations. customers should include design and operating safeguards to minimize these and other risks. skyworks assumes no liabi lity for applications assistance, customer product design, or damage to any equipment resulting from the use of skyworks products outside of stated published speci ? cations or parameters. skyworks, the skyworks symbol, and breakthrough simplicity are trademarks or registered trademarks of skyworks solutions, inc., in the united states and other countries. third-party brands and names are for identi ? cation purposes only, and are the property of their respective owners. additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 1. the leadless package family, which includes qfn, tqfn, dfn, tdfn and stdfn, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. a solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder c onnection. package information tdfn33-12 1 top view bottom view detail "a" side view 3.00 0.05 index area detail "a" 1.70 0.05 3.00 0.05 0.05 0.05 0.23 0.05 0.75 0.05 2.40 0.05 pin 1 indicator (optional) 0.40 0.05 0.45 0.05 0.23 0.05 0.1 ref c0.3 all dimensions in millimeters downloaded from: http:///

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