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1 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apri l 27, 2012 general description the AAT3691 batterymanager? is an integrated single cell lithium-ion (li-ion) battery charger ic, designed to operate from usb ports, ac adapter inputs, or from a cellular phone charger adapter up to an input voltage of typical 6.75v. for increased safety, the AAT3691 also includes over-voltage input protection (ovp) up to 28v. the AAT3691 precisely regulates battery charge voltage and current for 4.2v li-ion battery cells. the charge current can be programmed up to 1.6a for adp charging and 0.5a for usb charging by external resistors on the adpset/usbset pins. in the case of an over-voltage condition of adp or usb input power exceeding typical 6.75v, the internal series switch opens, blocking the damage to the battery and charging circuitry. the AAT3691 also includes a no-battery present input (nobat). when the nobat indicates that no battery is present, ovp block will prevent the input power from passing through the ovp block and suspend the charging function. battery charging status is continuously monitored for fault conditions. in the event of a battery over voltage or chip over thermal failure, the charger will automatically shutdown, protecting the charging device, control system and battery, until the fault condition is removed. the open drain status monitor output pin (stat) is adopted to report battery charging activity by active low. the AAT3691 comes in a thermally enhanced, space- saving, pb-free 16-pin 3x4 mm tdfn package and is specified for operation over the -40 c to +85 c tempera- ture range. features ? dual input usb and ac adapter input ? programmable constant current from 100ma to 1.6a for adp charge ? programmable constant current from 50ma to 0.5a for usb charge ? no battery present input detection ? 3.0v ~ 6.75v (typical) input voltage range ? over-voltage input protection up to 28v ? high level of integration with internal: ? power device ? reverse current blocking ? current sensing ? automatic recharge sequencing ? fast over-voltage protection turn off and release turn on time ? full battery charge auto turn off/sleep mode/charge termination ? charge status indicator ? automatic charge reduction ? automatic trickle charge for battery preconditioning ? thermal shutdown protection ? active digital thermal loop control ? power on reset and soft start ? active low enable with internal 200k resistor pull- down to gnd ? 3x4mm tdfn package applications ? ? digital still cameras ? ? mobile phones ? ? personal data assistants (pdas) ? ? other li-ion battery powered devices typical application AAT3691 10f batt- usbin battery pack batt+ on/off gnd bat r usbset usbset usb en usbch 2.2f adp adpin adpset r adpset stat adpch 2.2f nobat nobat voltage source ic 1f 1f r
2 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 pin descriptions pin # name type function 1 usb i input from usb port connector 2. usbch i/o output from usb ovp stage, input to battery charger. decouple with 2.2 f capacitor. 3 adp i input from adapter port connector 4 adpch i/o output from adp ovp stage, input to battery charger. decouple with 2.2 f capacitor. 5, 7, 10 ic i internally used. connect to gnd or leave oating. 6 stat o charge status indication pin, open drain. 8, 9 gnd connect to power ground 11 en i active low enable with internal 200k resistor pull-down to gnd. 12 adpset i adp charge current programming input pin. 13 usbset i usb charge current programming input pin. 14 nobat i no battery present input. logic ?high? indicates no battery. internal 1.6m pull-high resistor. 15 n/c no connection. 16 bat o connect to lithium-ion battery. pin configuration tdfn34-16 (top view) adp a dpch ic usb usbch 3 stat ic gnd nobat usbset adpset bat n/c en ic gnd 4 5 1 2 6 7 8 14 13 12 16 15 11 10 9
3 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 absolute maximum ratings 1 symbol description value units v adp ,v usb adp, usb input continuous 28 v v adpch, , v usbch charger input continuous -0.3 to 7.5 v v n bat, stat, en, adpset , usbset, nobat, ic -0.3 to 7.5 + 0.3 v t j operating junction temperature range -40 to 150 ? c t lead maximum soldering temperature (at leads) 300 ? c thermal information 2 symbol description value units ? ja maximum thermal resistance (tdfn 3x4) 50 ? c/w p d maximum power dissipation 2 w 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at co nditions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any one time . 2. mounted on a fr4 board.
4 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 electrical characteristics 1 v adp = v usb = 5v, t a = -25c to +85c, unless otherwise noted. typical values are at t a = 25c. symbol description conditions min typ max units operation v adp_max, v usb_max input over-voltage protection range 28 v v adp, v usb adp and usb normal operating input voltage range 3.0 6.5 v i adp_op, i usb_op operating current v adp or v usb = 5v, charge current = 100ma, en = 0v 0.5 1.5 ma i sd(off) shutdown supply current v adp or v usb = 5v, en = 5v 8 a i standby standby mode current charge terminated 300 a i bat leakage current from bat pin v bat = 4v, usb and adp open 1 4 a over-voltage protection v ovpt over-voltage protection trip voltage rising edge 6.5 6.75 7.0 v hysteresis 300 mv battery charger v uvlo_adp, v uvlo_usb under-voltage lockout threshold rising edge 3.0 v uvlo hysteresis 150 mv voltage regulation v bat_eoc output charge voltage regulation 4.158 4.20 4.242 v ? v ch /v ch output charge voltage tolerance 0.5 % v min preconditioning voltage threshold 2.4 2.6 2.8 v v rch battery recharge voltage threshold v bat_eoc - 0.1 v battery charging device r ds(on) charging and ovp total on resistance v adp or v usb = 5v, t a = 25c 600 m ? current regulation i lim_adp adp charge current programmable range 100 1600 ma i lim_usb usb charge current programmable range 50 500 ma i ch_cc constant-current mode charge current v bat = 3.6v -10 10 % v adpset , v usbset adpset, usbset pin voltage 2v ki adpset charge current set factor: i ch_cc /i adpset constant current mode, v bat = 3.6v 800 ki usbset charge current set factor: i ch_cc /i usbset constant current mode, v bat = 3.6v 800 i ch_trk trickle charge current r adpset = 8k ? 51015 % i ch_cc i ch_term charge termination threshold current i ch_cc 800ma 8 10 12 % 1. the AAT3691 is guaranteed to meet performance specifications over the -40c to +85 c operating temperature range and are assured by design, characterization and correla- tion with statistical process controls.
5 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 electrical characteristics (continued) 1 v adp = v usb = 5v, t a = -25c to +85c, unless otherwise noted. typical values are at t a = 25c. symbol description conditions min typ max units logic control / battery protection v en#(h) input high threshold v adp = 5v 1.2 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 48ma v nobat(h) no battery present input high threshold 1.2 v v nobat(l) no battery present input low threshold 0.4 v v bovp battery over-voltage protection threshold 4.4 v t respov over-voltage response time v adp , v usb voltage step up signal from 6v to 8v 0.5 1.0 s t ovpon ovp switch ovp release turn-on delay time v adp voltage step down signal from 8v to 6v, r load = 10 ? , c adpch = 1 f 5 s t ovpstarton ovp switch start up turn-on delay time v adp voltage step up signal from 0v to 5v, r load = 10 ? , c adpch = 1 f 130 s t ovpr ovp switch turn-on rise time r load = 10 ? , c adpch = 1 f 100 s t shdn chip thermal shutdown temperature thermal shutdown threshold 140 c hysteresis 15 1. the AAT3691 is guaranteed to meet performance specifications over the -40c to +85 c operating temperature range and are assured by design, characterization and correla- tion with statistical process controls.
6 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 typical characteristics over-voltage protection vs. temperature temperature (c) v adp or v usb (v) -40 -20 0 20 40 60 80 6.50 6.55 6.60 6.65 6.70 6.75 6.80 power sweep low to high power sweep high to low end of charge voltage vs. supply voltag e (r adpset = 1k, r usbset = 3.2k ) v adp or v usb (v) v eoc (v) 4.4 4.8 5.2 5.6 6.0 6.4 6.8 4.18 4.19 4.20 4.21 4.22 usb adp i charge vs. r adpset r adpset (k) i charge (ma) 1 10 100 10 100 1000 10000 i charge vs. r usbset r usbset (k) i charge (ma) 1 10 100 10 100 1000 battery recharge voltage threshold vs. supply voltag e (r adpset = 1k; r usbset = 3.2k; c bat = 22f ) v adp or v usb (v) v rch (v) 4.5 4.9 5.3 5.7 6.1 6.5 3.96 3.98 4.00 4.02 4.04 4.06 4.08 4.10 usb adp battery recharge voltage threshold vs. temperature (v adp = v usb = 5v; r adpset = 1k; r usbset = 3.2k; c bat = 22f ) temperature (c) v rch (v) -40 -20 0 20 40 60 80 4.00 4.02 4.04 4.06 4.08 4.10 usb adp
7 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 typical characteristics end of charge voltage vs. temperature (r adpset = 1k; r usbset = 3.2k ) temperature (c) v eoc (v) -40 -20 0 20 40 60 80 4.18 4.19 4.20 4.21 4.22 usb adp charge current vs. temperature (v adp = v usb = 5v; v bat = 3.6v; r adpset = 1k; r usbset = 3.2k ) temperature (c) i ch (ma) -40 -20 0 20 40 60 80 0 200 400 600 800 1000 1200 1400 1600 1800 adp usb charging current vs. battery voltage (v adp = v usb = 5v; r adpset = 1k; r usbset = 3.2k ) v bat (v) i ch (ma) 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 0 200 400 600 800 1000 1200 1400 1600 1800 adp usb usb charging current vs. supply voltage (r usbset = 3.2k ) v usb (v) i ch_usb (ma) 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 0 100 200 300 400 500 600 v bat = 3.3v v bat = 3.6v v bat = 3.9v adp charging current vs. supply voltage (r adpset = 1k ) v adp (v) i ch_adp (ma) 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 0 200 400 600 800 1000 1200 1400 1600 1800 v bat = 3.3v v bat = 3.6v v bat = 3.9v usb charging current vs. supply voltage (r usbset = 3.2k ) v usb (v) i ch_usb (ma) 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 0 100 200 300 400 500 600 -40c 0c 25c 50c 85c
8 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 typical characteristics adp charging current vs. battery voltage (v adp = 5v ) v bat (v) i ch_adp (ma) 2.5 2.9 3.3 3.7 4.1 4.5 0 300 600 900 1200 1500 1800 r set = 1k r set = 1.14k r set = 1.33k r set = 1.6k r set = 2k r set = 3.2k r set = 5.33k r set = 16k usb charging current vs. battery voltage (v usb = 5v ) v bat (v) i ch_ usb (ma) 0 100 200 300 400 500 600 4.5 4.0 3.5 3.0 2.5 r set = 3.2k r set = 4k r set = 5.33k r set = 8k r set = 16k r set = 32k nobat high input threshold vs. input power v usb or v adp (v) nobat v ih (v) 3.0 3.6 4.2 4.8 5.4 6.0 6.6 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 -40c 25c 85c nobat low input threshold vs. input power v usb or v adp (v) nobat v il (v) 3.0 3.6 4.2 4.8 5.4 6.0 6.6 0.40 0.45 0.50 0.55 0.60 0.65 0.70 -40c 25c 85c enable input high threshold vs. input power v usb or v adp (v) en v ih (v) 4.0 4.4 4.8 5.2 5.6 6.0 6.4 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 -40c 25c 85c enable input low threshold vs. input power v usb or v adp (v) en v il (v) 4.0 4.4 4.8 5.2 5.6 6.0 6.4 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 -40c 25c 85c
9 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 functional description the AAT3691 is a high performance battery charger designed to charge single cell lithium ion or polymer batteries with up to 1600ma charging current from an adaptor (adp) power source, or with up to 500ma charging current from an usb power source. the AAT3691 is a stand-alone charging solution, with just a few external component required for complete function- ality. both input paths include a fast turn-off over-volt- age protection (ovp) circuit with voltage up to +28v and an under-voltage lockout level of 3.0v. the AAT3691 automatically selects the charging source from usb or adp according to adp and usb voltage. the adp path is always the high priority charging path when adp voltage is higher than 4.5v. the charging current is determined by the selected charging path and its exter- nal set resistor (r set ). usb charging uses an automatic charge reduction loop control allow battery charging with limited available cur- rent from a usb port while maintaining the regulated port voltage. this system assures that the battery charge function will not overload a usb port while charg- ing if other system demands also share power with the respective port supply. during adapter charging, high set charging current or high ambient operating temperature may cause the AAT3691 junction temperature to rise up to 110c. a special digital thermal loop control system is employed to maximize charging current by dynamically decreasing the battery charging current. thermal protection shuts down the AAT3691's charging function when internal dissipation becomes excessive, while ovp function still works. the junction over-temper- ature threshold is 140c with 15c of hysteresis. once an over-temperature condition is removed, the charging function automatically recovers. the status monitor output pin (stat) is designed to indi- cate the battery charge status with open-drain structure by directly driving one external led. battery charging operation regardless of which charge input function is selected (adapter input or usb input), the AAT3691 has three basic modes for the battery charge cycle: precondition- ing (trickle) charge, constant current/fast charge, and constant voltage charge. when no automatic charge reduction mode or digital thermal loop is triggered, the charge profile is controlled as shown in figure 1. functional block diagram charge control current compare current compare reverse blocking bat uvlo over-temp. protect gnd stat usb en cv/precharge usbch usbset charge status a dpset nobat reverse blocking ovp sense and control ovp sense and control adpch adp ovp switch ic
10 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 regulated current constant current mode voltage threshold trickle charge and termination threshold i = cc/10 i = max cc preconditioning trickle charge phase constant current charge phase constant voltage charge phase charge current battery voltage time battery charge current battery voltage charge complete voltage figure 1: charge current vs. battery voltage profile during charging phases. battery charging commences only after the AAT3691 checks several conditions in order to maintain a safe charging environment. the input supply must be above the minimum operating voltage and the enable pin must be low. when the battery is connected to the bat pin and the nobat pin indicates there is a battery connected, the AAT3691 checks the condition of the battery and determines which charging mode to apply. if the battery voltage is below v min , then the device begins trickle charging by charging at 10% of the programmed con- stant current. for example, if the programmed current is 500ma, then the trickle charge current is 50ma. trickle charging is 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 volt- age differential is at its highest. trickle charging contin- ues until the battery voltage reaches v min . at this point, the AAT3691 begins constant current charging. the cur- rent value for this mode is programmed by the external resistors from the adpset and usbset pin to ground. programmed current can be set from a minimum of 100ma up to a maximum of 1.6a for an adp power source, and from a minimum of 50ma up to a maximum of 500ma for a usb power source . constant current charging continues until the battery voltage reaches the voltage regulation point, v bat_eoc . when the battery volt- age reaches v bat_eoc (typical 4.2v), the AAT3691 will switch to constant voltage mode. constant current charge will continue until the charging current is reduced to 10% of the programmed current. after the charge cycle is complete, the AAT3691 turns off the series pass device and automatically goes into standby mode. during this time, the series pass device will block current in both directions, therefore preventing the battery from discharging through the ic. the AAT3691 remains in standby mode until either 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 AAT3691 will monitor all parameters and resume charging in the most appropri- ate mode. over-voltage protection in normal operation an ovp switch acts as a slew-rate controlled load switch, connecting and disconnecting the power supply from adp to adpch and usb to usbch. a low-resistance mosfet is used to minimize the voltage drop between the voltage source and the charger and to reduce the power dissipation. when the voltage on the input exceeds the 6.75v (typical) voltage limit, the device immediately turns off the internal ovp switch, disconnecting the load from the abnormal voltage and preventing damage to any downstream components. on initial power-up with low and battery present, if v usb/adp < v uvlo (3v maximum), the ovp switch is held off; if v uvlo < v usb/adp < 6.75v (typical), the ovp switch will turn on after a 130 s typical internal delay; if v usb/adp rises above 6.75v (typical), the ovp switch is turned off after a 0.5 s typical internal delay.
11 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 system operation flowchart power on reset ovp (6.75v) v usb or v adp v uvlo_adp or v uvlo_usb (3v) preconditioning test v min > v bat current phase test v in > v bat_eoc voltage phase test i bat > i term yes no yes yes preconditioning (trickle charge) constant current charge mode constant voltage charge mode yes yes yes charge completed no recharge test v rch > v bat yes no nobat indicates no battery no yes v usbch < 4.5v auto charge reduction loop control ovp switch off usbch = adpch = 0v no no no enable yes no usbch = usb, adpch = adp v adpch > v uvlo_adpch (3.5v) no v usbch > v uvlo_usbch (3.5v) no preconditioning test v min > v bat current phase test v in > v bat_eoc voltage phase test i bat > i term no yes preconditioning (trickle charge) constant current charge mode constant voltage charge mode yes yes yes charge completed no recharge test v rch > v bat yes no device thermal loop monitor t j > 115c thermal loop current reduction in c.c. mode no no yes adapter charge usb charge
12 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 application information charge sources the AAT3691 operates from sources of an adapter or usb interface. the internal system control will always select the adapter input to charge the battery rather than the usb input if the adapter voltage is above 4.5v. the normal charging input voltage range is up to typical 6.75v. the device can withstand up to 28v on the adapt- er or usb inputs without damage to the ic. if v adp or v usb is greater than 6.75v, the internal over-voltage protec- tion circuitry disables charging until the input falls bel ow typical 6.55v . ac adapter/usb system power charging adapter mode in the adapter mode, constant current charge levels up to 1.6a can be programmed by the user. the fast charge current for the adapter input mode is set by the r adpset resistor connected between adpset and ground. it is programmed by the following equations: 2 r adpset i adp_cc = ki adpset 2 i adp_cc r adpset = ki adpset with ki adpset = 800. table 1 gives the recommended 1% tolerance metal film resistance values for a desired con- stant current charge level. thermal loop control to protect the linear charging ic from thermal problems, a special thermal loop control system is used to maxi- mize charging current under adapter charge mode. the thermal management system measures the internal cir- cuit die temperature and reduces the fast charge current when the die exceeds the preset internal temperature control threshold. once the thermal loop control becomes active, the fast charge current is initially reduced by a factor of 0.44. the initial thermal loop current can be estimated by the following equation: i tloop = i cc 0.44 i ch_cc (ma) r adpset (k )r usbset (k ) 50 32.4 75 21.5 100 16 16 200 8.06 8.06 300 5.36 5.36 400 4.02 4.02 500 3.24 3.24 600 2.67 700 2.32 800 2 900 1.78 1000 1.60 1100 1.47 1200 1.33 1300 1.24 1400 1.15 1500 1.07 1600 1 table 1: standard 1% metal film resistor values for constant current setting. the thermal loop control re-evaluates the circuit die temperature every three seconds and raises the fast charge current in small steps to the full fast charge cur- rent level. figure 2 illustrates the thermal loop function at 1a fast charge current as the ambient temperature increases and recovers. in this manner the thermal loop controls the system charge level, and the AAT3691 pro- vides the highest level of constant current in the fast charge mode for any possible valid ambient temperature condition. 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 time (10s/div) charge current (0.2a/div) a mbient temperature decreases ambient temperature increases figure 2: digital thermal loop function at 1a fast charge current with ambient temperature increasing and recovering.
13 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 adapter input charge inhabit and resume the AAT3691 has an under-voltage lockout feature so that if the charger input supply adp pin drops below the uvlo threshold, the charger will suspend charging. when the uvlo condition is removed and v adpch > v bat , the system charge control assesses the state of charge of the battery cell and automatically resumes charging in the appropriate phase (pre-conditioning trickle charge, constant current charge, constant voltage charge or end of charge) according to the condition of the battery. usb mode the AAT3691 also provides an input for intelligent usb charging. when no voltage is present on the adapter input pin or adapter input is below 4.5v , the charge con- troller will automatically switch to accepting power from the usb input. the usb charge may be user programmed to any level between 50ma and 500ma by selecting the appropriate resistor values for r usbset . 2 r usbset i usb_cc = ki usbset 2 i usb_cc r usbset = ki usbset among them, ki usbset is 800. refer to table 1 for recom- mended r usbset values for the desired usb input constant current charge levels. usb charge reduction in many instances, product system designers do not know the real properties of a potential usb port used to supply power to the battery charger. typically, powered usb ports found on desktop and notebook pcs should supply up to 500ma. if a usb port being used to supply the charger is unable to provide the programmed fast charge current or if the system under charge must share supply current with other functions, the AAT3691 auto- matically reduces usb fast charge current to maintain port integrity and protect the host system. the usb charge reduction system becomes active when the voltage on the usbch input falls below the usb charge reduction threshold, typically 4.5v. the charge reduction system reduces the fast charge current level in a linear fashion until the voltage sensed on the usb input recovers above the charge reduction threshold voltage. usb input charge inhibit and resume the AAT3691 uvlo and power on reset feature functions when the usb input pin voltage level drops below the uvlo threshold. at this point, the charger suspends charging and shuts down. when power is re-applied to the usb pin or the uvlo condition recovers, the system charge control will assess the state of charge on the bat- tery cell and automatically resume charging in the appropriate mode for the condition of the battery. enable / disable the AAT3691 provides an enable function to allow the normal operating input voltage to pass through and con- trol the ic charging. the enable (en) pin is active low and is pulled down to ground by an internal 200k resis- tor . when pulled to a logic high level, the AAT3691 is shut down and forced into the sleep state during which input voltage up to 28v will be blocked and charging be halted regardless of the battery voltage or charging state. when the device is re-enabled, the ovp block will automatically reassess the input voltage and allow the normal operating voltage to pass through. if a battery is also present (nobat is low), the charge control circuit will automatically reset and resume charging with the appropriate charging mode based on the battery charge state and measured cell voltage. over-temperature shutdown thermal protection completely disables charging when internal dissipation exceeds the junction over-tempera- ture threshold, which is 140c with 15c of hysteresis. once the over-temperature fault condition is removed, the charge function automatically recovers. battery charge status indication the AAT3691 has one status led driver output. the led can indicate simple functions such as battery charging, charge complete, and charge disabled. description en led status battery charging low on charge complete low off charge disabled high off table 2. led status conditions.
14 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 the led anodes should be connected to either v usbch or v adpch , depending upon the system design requirements. the leds should be biased with as little current as nec- essary to create reasonable illumination; therefore, a ballast resistor should be adopted to limit the current flowing through the led by connecting it with the led in series between stat and v usbch or v adpch . led current consumption will add to the overall thermal power bud- get for the device package, so led drive current should be kept 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 value can be estimated using the following formulas: to connect to adpch: v adpch - v fled i led r = to connect to usbch: v usbch - v fled i led r = for example, using a red led with 2.0v v f @ 2ma, cal- culate r under 5.5v v adpch : 5.5v - 2.0v 2ma r = = 1.75k capacitor selection input capacitor an input capacitor is used to filter the input voltage by placing a decoupling capacitor between the adp, adpch, usb and usbch pins and ground. an input capacitor in the range of 1 f to 10 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. this input capac- itor range is also suitable for a system with an external power supply source, such as a typical ac-to-dc wall adapter. it will minimize switching or power bounce effects when the power supply is ?hot plugged?. likewise, a 2.2 f or greater input capacitor is recommended for the usb input to help buffer the effects of usb source power switching, noise, and input cable impedance. output capacitor the AAT3691 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. in a fast charge application with current above 1a, a 22 f output capacitor is required to obtain an accurate recharge volt- age threshold. if the AAT3691 is used in applications where the battery can be removed from the charger, such as in the case of desktop charging cradles, an out- put capacitor value greater than 10 f may be required to prevent the device from cycling on and off when no battery is present. thermal considerations the actual maximum charging current is a function of the charge input voltage (usbch and adpch), the bat- tery voltage at the bat pin, the ambient temperature, the rising temperature when charge current passing through the r ds(on) of the charging pass, and the thermal impedance of the package. the maximum programma- ble current may not be achievable under all operating parameters. the AAT3691 is offered in a 3x4mm tdfn package which can provide up to 2.0w of power dissipation when properly soldered 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 gen- erating devices in a given application design. the ambi- ent temperature around the charger ic will also have an effect on the thermal limits of a battery charging appli- cation. the maximum limits that can be expected for a given ambient condition can be estimated by the follow- ing discussion: first, the maximum power dissipation for a given situa- tion should be calculated: p d = [(v in - v bat ) i cc + (v in i op )] where: p d = total power dissipation of the AAT3691 v in = v adp or v usb , depending on which mode is selected v bat = battery voltage at the bat pin i cc = maximum constant fast charge current pro- grammed for the application i op = quiescent current consumed by the charger ic for normal operation.
15 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 next, the maximum operating ambient temperature for a given application can be estimated based on the ther- mal resistance of the 3x4 tdfn package when suffi- ciently mounted to a pcb layout and the internal thermal loop temperature threshold. t a = t j - ( ja p d ) where: t a = ambient temperature in c t j = maximum device junction temperature below the thermal loop threshold p d = total power dissipation by the device ja = package thermal resistance in c/w. example: for an application where the fast charge current for the adapter mode is set to 1a, v adp = 5.0v, and the worst case battery voltage is 3.6v, what is the maximum ambi- ent temperature at which the digital thermal loop limit- ing will become active? given: v adp = 5.0v v bat = 3.6v i cc = 1 a i op = 0.25ma t j = 110c ja = 50c/w the device power dissipation for the stated condition can be calculated as below: p d = (5.0 ? 3.6v) 1a + (5.0v 0.25ma) 1.4w the maximum ambient temperature is t a = 110c - (50c/w 1.4w) = 40c therefore, under the stated conditions for this worst case power dissipation example, the AAT3691 will enter the digital thermal loop and lower the fast charge con- stant current when the ambient operating temperature rises above 40c. printed circuit board layout considerations for the best results, it is recommended to physically place the battery pack as close to the AAT3691 bat pin as pos- sible. to minimize voltage drops on the pcb, keep the high current carrying traces adequately wide. for maxi- mum power dissipation of the AAT3691 tdfn package, the exposed pad should be soldered to the board ground plane to further increase local heat dissipation. a ground pad below the exposed pad is strongly recommended.
16 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 c11 1f/50v c12 2.2f/10v c22 2.2f/10v c3 10f c21 1f/50v usb usbch adp adpch a dpch 1.74k r1 led1 red 2 1 3 j1 adpch usbch r2 disable r3 usb adp usbch bat j2 bat AAT3691 usbch 2 usb 1 adp 3 usbset 13 nobat 14 adpch 4 ic 5 en 11 adpset 12 ic 10 ep stat 6 ic 7 n/c 15 bat 16 gnd 8 gnd 9 u1 figure 3: AAT3691 evaluation board schematic. figure 4: AAT3691 evaluation board figure 5: AAT3691 evaluation board top side layout. bottom side layout.
17 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 component part number description manufacturer u1 AAT3691irn-t1 0.5a usb port /1.6a adapter lithium-lon; 16-pin 3x4 tdfn package skyworks r1 rc0603fr-071k74l res 1.74k 1/10w 1% 0603 smd yageo r2 rc0603fr-073k24l res 3.24k 1/10w 1% 0603 smd yageo r3 rc0603fr-072kl res 1.6k 1/10w 1% 0603 smd yageo c3 grm188r60j106m cap ceramic 10 f 0603 x5r 6.3v 20% murata c11, c21 grm21br71h105k cap ceramic 1 f 0805 x7r 50v 10% murata c12, c22 grm188r61a225k cap ceramic 2.2 f 0603 x5r 10v 10% murata j1 tmm-103-03-t-s conn. 3-pin header, 2.54mm pitch samtec j2, disable tmm-102-03-t-s conn. 2-pin header, 2.54mm pitch samtec led1 0805krct red led; 0805 hb adp, usb, bat dg308-2.54-02-14 multi-position micro pcb terminal blocks, 2.54mm, 2 pin, green degson adpch, usbch 5010k-nd red test point keystone g1, g2 5011k-nd black test point keystone table 3: AAT3691 evaluation board bill of materials.
18 AAT3691 data sheet dual input 1.6a linear charger with 28v ovp in a 3x4 tdfn package skyworks solutions, inc. ? phone [781] 376-3000 ? fax [781] 376-3100 ? sales@skyworksinc.com ? www.skyworksinc.com 201894b ? skyworks proprietary information ? products and product information are subject to change without notice. ? apr il 27, 2012 copyright ? 2012 skyworks solutions, inc. all rights reserved. information in this document is provided in connection with skyworks solutions, inc. (?skyworks?) products or services. these m aterials, including the information contained herein, are provided by skyworks 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 informati on 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 information provided here- under, including the sale, distribution, reproduction or use of skyworks products, information or materials, except as may be p rovided 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. sk yworks 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 co nditions, posted at www.skyworksinc.com, are incorporated by reference. ordering information package nobat input eoc voltage marking 1 part number (tape and reel) 2 tdfn34-16 active high 4.2 4txyy AAT3691irn-4.2-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. package information tdfn34-16 3 3.000 0.050 1.600 0.050 0.000 + 0.100 -0.000 0.203 ref 0.750 0.050 4.000 0.050 3.300 0.050 index area detail "a" top view bottom view side view 0.450 0.050 0.230 0.050 0.450 0.050 detail "a" all dimensions in millimeters. 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . 3. 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.

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