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for information on other maxim products, visit maxim? website at www.maxim-ic.com. general description the MAX8600A single-input linear battery charger safe- ly charges single-cell li+ batteries. charging is opti- mized for li+ cells using a control algorithm that includes low-battery precharging, voltage and current- limited fast-charging, and top-off charging, while con- tinuously monitoring the battery for overvoltage, over/under temperature, and charging time. charger timeout protection is programmable, and the status is indicated by three open-drain outputs. the MAX8600A linear charger optimizes charging time by adjusting the charge rate to accommodate the ther- mal characteristics of a given application. there is no need to reduce the maximum charge current to accom- modate worst-case charger power dissipation. the MAX8600A is a variation of the max8600 with improved dropout and other spec changes. see maxim? website for an outline of max8600/MAX8600A differences. the MAX8600A is available in a 3mm x 3mm power- enhanced tdfn package. applications cell phones portable media players digital cameras mp3 players pdas wireless appliances gps features ? low dropout -0.188v at 0.75a ? up to 1a programmable fast-charge ? 5% charge-current accuracy ? logic-low enable input ? 14v input overvoltage protection ? programmable on-chip charge timer ? battery thermistor input ? three charger-status outputs ? thermally optimized charge rate ? 14-pin, 3mm x 3mm tdfn package MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer ________________________________________________________________ maxim integrated products 1 19-3205; rev 1; 1/09 evaluation kit available ordering information part temp range pin-package top mark MAX8600A etd+ -40? to +85? 14 tdfn-ep* (3mm x 3mm) (t1433-2) aef bat thm en ct off on flt dc gnd seti pok chg MAX8600A dc input 4.1v to 5.9v led logic supply li+ + safe dc typical operating circuit 8 9 10 11 12 13 14 7 6 5 4 3 2 1 MAX8600A tdfn top view seti bat thm gnd ct n.c. bat flt dc dc chg pok dc en + pin configuration * ep = exposed pad. + denotes a lead(pb)-free/rohs-compliant package.
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer 2 _______________________________________________________________________________________ absolute maximum ratings stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. pok to gnd.................................................-0.3v to (dc + 0.3v) dc to gnd .............................................................-0.3v to +16v bat, ct, chg , en , flt , seti, thm to gnd ......................................................-0.3v to +5.5v continuous power dissipation (t a = +70?) 14-pin tdfn 3mm x 3mm multilayer pcb (derate 24.4mw/? above +70?)...................................................... 1951.2mw operating temperature range ...........................-40? to +85? junction temperature range ............................-40? to +150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? electrical characteristics (v dc = 5v, v bat = 3.6v, v en = 0v, r seti = 2k , c ct = 0.068?, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter conditions min typ max units dc input voltage range 014v input operating range (note 2) 4.1 6.0 v input undervoltage threshold when pok goes low, dc rising, 500mv hysteresis 3.89 4.0 4.10 v input overvoltage threshold when pok goes high, dc rising, 200mv hysteresis 6.2 6.5 6.8 v input supply current i bat = 0ma, r thm = 10k = = = bat t a = +25? 4.179 4.2 4.221 bat regulation voltage i bat = 0ma t a = -40? to +85? 4.166 4.2 4.234 v bat restart fast-charge threshold from bat regulation voltage -180 -150 -120 mv r seti = 1.5k = = = , v bat = 2.0v 67.5 75 82.5 ma soft-start time ramp time to fast-charge current 1.2 ms bat prequal threshold when charging current changes, bat rising, 170mv hysteresis 2.30 2.50 2.54 v bat leakage current v dc = 0v, v bat = 4.2v 0.001 5a control inputs and outputs seti r seti resistance range guaranteed by charging current 1.5 5.0 k
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer _______________________________________________________________________________________ 3 electrical characteristics (continued) (v dc = 5v, v bat = 3.6v, v en = 0v, r seti = 2k , c ct = 0.068?, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter conditions min typ max units en rising 1.6 logic input thresholds falling 0.4 v logic input resistance to gnd 250 485 1000 k pok logic output voltage, low i pok = 100? 29 100 mv t a = +25? 0.001 1 logic output leakage current, high v pok = v dc = 16v t a = +85? 0.01 ? chg , flt logic output voltage, low i c h g = i f l t = 1 m a 12 100 mv t a = +25? 0.001 1 logic output leakage current, high v chg = v flt = 5.5v, v dc = 0v t a = +85? 0.01 ? chg r seti = 1.5k 60 r seti = 2k 30 45 60 chg /top-off current threshold i bat falling, battery is charged r seti = 5k 18 ma thm thm pullup resistance match to thermistor resistance at t a = +25? -1% 10 +1% k thm resistance, hot r thm falling, 420 hysteresis 3.72 3.94 4.13 k thm resistance, cold r thm rising, 2.7k hysteresis 26.7 28.3 29.7 k thm resistance, disabled r thm falling, 230 hysteresis 240 309 370 timers, ct timer accuracy c ct = 0.068? -20 +20 % prequal time limit from pok low and en low to end of prequal charge, bat < 2.4v, c ct = 0.068? 34.8 min charge time limit from pok low and en low to end of charge, c ct = 0.068? 334 min top-off time limit from chg high to done, c ct = 0.068? 69.6 min thermal loop thermal-limit temperature juncti on tem p er atur e w hen the char g e cur r ent i s r ed uced , t j r i si ng +100 ? thermal-limit gain reduction of i bat for increase of t j , i bat /t j (over +100?) 5 %/? note 1: limits are 100% production tested at t a = +25?. limits over the operating temperature range are guaranteed by design and characterization. note 2: guaranteed by undervoltage- and overvoltage-threshold testing. for complete charging, the input voltage must be greater than 4.35v.
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer 4 _______________________________________________________________________________________ typical operating characteristics (v dc = 5v, r seti = 2k , v bat = 3.6v, max8601 evaluation kit with thermal resistance of 50?/w. t a = +25?, unless otherwise noted.) 0 300 200 100 500 400 900 800 700 600 1000 0 2 4 6 8 10 12 14 supply current vs. input voltage MAX8600A toc01 input voltage (v) supply current ( a) v en = 0v 0 150 100 50 250 200 450 400 350 300 500 02468101214 disabled supply current vs. input voltage MAX8600A toc02 input voltage (v) supply current ( a) v en = 5v 0 200 400 600 800 1000 0 1.0 0.5 1.5 2.0 2.5 3.0 3.5 4.0 4.5 charge current vs. battery voltage MAX8600A toc03 v bat (v) charge current (ma) r seti = 1.5k r seti = 3k r seti = 2k dashed data taken with pulse testing to avoid thermal limit 0 200 400 600 800 1000 1200 02468101214 charge current vs. dc voltage MAX8600A toc04 v dc (v) charge current (ma) r seti = 1.5k r seti = 2k r seti = 3k dashed data taken with pulse testing to avoid thermal limit 0 300 200 100 400 500 600 700 800 900 1000 00.4 0.2 0.6 0.8 1.0 charge current vs. input voltage headroom MAX8600A toc05 v in - v bat (v) charge current (ma) 4.180 4.190 4.185 4.200 4.195 4.205 4.210 -40 10 -15 35 60 85 battery regulation voltage vs. ambient temperature MAX8600A toc06 t a ( c) battery regulation voltage (v) 0 300 200 100 400 500 600 700 800 900 1000 -40 10 -15 35 60 85 charge current vs. ambient temperature (750ma charge) MAX8600A toc07 t a ( c) charge current (ma) v bat = 4v v bat = 3.6v
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer _______________________________________________________________________________________ 5 pin name function 1, 7 bat battery connection. the ic delivers charging current and monitors battery voltage using bat. bypass bat to gnd with a 2.2? or larger ceramic capacitor. connect both bat inputs together externally. bat is high impedance when the ic is disabled. ensure that all bat pins are connected together. 2 seti dc charge-current programming pin. connect a resistor from seti to gnd to set the maximum charging current (i bat = 1500v/r seti ), the prequal current, and the chg done threshold. monitor charging current by measuring this pin voltage. seti is high-impedance when en is high, or dc is at gnd. 3 thm thermistor input. connect a 10k ntc thermistor, in close proximity to the battery, from thm to ground to monitor the battery temperature. the ic suspends charging when r thm is outside the hot and cold limits. disable thermistor functionality by connecting thm to gnd. thm is high impedance when en is high or dc is at gnd. 4 gnd ground 5ct timing capacitor input. connect a capacitor from ct to gnd to set the precharge timeout, top-off time, and fast-charge timeout. connect ct to gnd to disable the timers. ct is high impedance when en is high or dc is at gnd. 6 n.c. no connection. make no external circuit connection. 8 en active-low enable input. drive low or connect en to gnd to enable the charger. drive en high to disable the charger. en has an internal 470k pulldown resistance to gnd. 10 pok power-ok monitor. pok is an open-drain output that pulls low when a valid charging source is detected. pok is high impedance when dc voltage is outside valid range. pok remains active monitoring dc with the charger enabled or disabled. pin description typical operating characteristics (continued) (v dc = 5v, r seti = 2k , v bat = 3.6v, max8601 evaluation kit with thermal resistance of 50?/w. t a = +25?, unless otherwise noted.) 100 400 300 200 500 600 700 800 900 1000 1100 -40 10 -15 35 60 85 charge current vs. ambient temperature (1a charge) MAX8600A toc08 t a ( c) charge current (ma) v bat = 4v v bat = 3.6v r seti = 1.5k 0 100 200 300 400 500 600 700 800 0.010 0.045 0.080 0.115 0.150 fast-charge time vs. c ct MAX8600A toc09 c ct ( f) fast-charge time (min)
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer 6 _______________________________________________________________________________________ pin name function 11 chg charging-status output. chg pulls low when the battery is above 2.5v and being charged with a current greater than 6% of the current programmed with r seti . chg is high impedance when the charger is in prequal, top-off, or disabled. 9, 12, 13 dc dc input source. connect directly to a 4.5v to 6.0v charging source. bypass dc to gnd with 1? or greater. dc is overvoltage protected to 14v. ensure that all dc pins are connected together. 14 flt fault status output. flt pin pulls low when the fast-charge or prequal timers expire and the battery voltage is not above the required threshold. clear the fault by raising en or dropping dc to gnd (remove input power). ep exposed pad. connect ep to the gnd plane for optimum thermal dissipation. pin description (continued) any state fault chg = high flt = low i bat < 90/r seti and v bat 4.2v set timer = 0s v dc invalid or v dc < v bat or en high off pok = monitors input chg = high, flt = high i bat = 0ma en low and pok good set timer = 0s prequal pok = low, chg = high, flt = high i bat = 150/r seti done pok = low, chg = high, flt = high, i bat = 0ma top-off fast-charge pok = low, chg = low, flt = high, v bat 4.2v, i bat 1500/r seti suspend pq pok = low, chg = high, flt = high, i bat = 0ma, timer halted suspend fc timer > 34.8min timer > 334min timer > 69.6min pok = low, chg = high, flt = high, v bat 4.2v i bat < 150/r seti and v bat < 4.2v set timer = 0s note: all timer values are for c ct = 0.068 f thm not ok thm ok pok = low, chg = high, flt = high, i bat = 0ma, timer halted v bat < 2.37v set timer = 0s thm not ok thm ok v bat < 4.1v set timer = 0s v bat > 2.5v set timer = 0s figure 1. charger state diagram
detailed description the MAX8600A is a single-cell li+ battery charger. charging is optimized for li+ cells using a control algo- rithm that includes low-battery precharging, charging with simultaneous voltage and current compliance, and top-off charging. the battery is continuously monitored for over/under temperature, and charging is suspended if the temperature is out of range. charging is also ter- minated when the input source voltage is greater than 6.5v, or after excess charging time (fault). charger timeout protection is programmable. charger status is indicated by three-open drain outputs: pok , chg , and flt . an input overvoltage protection circuit prevents charging from improper input sources. the MAX8600A reduces charging time by continuously adjusting the charge rate to accommodate the thermal characteristics of a given application. there is no need to reduce the maximum charge current based on worst-case supply voltage, temperature, and thermal resistance. dc charging the MAX8600A is designed to charge a single-cell li+ battery from a dc source voltage between 4.1v and 6.0v. the precharge current, charge current, and top- off threshold are programmable with r seti . en charger-enable input en is a logic input (active low) that enables the charger. drive en high to disable the charger-control circuitry. drive en low or connect to gnd for normal operation. soft-start to prevent input transients, the rate of change of charging current is limited. when the charger is turned on or when the input source is changed, charge current is ramped from 0 to the set current value in typically 1.2ms. this is done to ensure that the dc source is not subjected to a severe load current step. charge-current ramp-up is also limited when transition- ing from prequal to fast-charge. there is no di/dt limit- ing, however, if i set is changed suddenly using a switch at r seti . thermal-limit control the MAX8600A features a thermal limit that reduces the charge current when the die temperature exceeds +100?. as the temperature increases above +100?, the ic lowers the fast-charge current compliance by 5%/?. chg charge-indicator output chg is an open-drain output that indicates charger sta- tus. chg goes low during charge cycles where v bat is greater than 2.5v and i bat is greater than 6% of the maximum charge current set by r seti . when the MAX8600A is used in conjunction with a microproces- sor (?), connect a pullup resistor between chg and the logic i/o voltage to indicate charge status to the ?. alternatively, chg can sink up to 20ma for an led charge indicator. fault indicator ( flt ) the MAX8600A contains an open-drain flt output to signal the user when a fault occurs. flt goes low if the charger is in prequal and the prequal timer expires, or if the charger is in fast-charge and the fast-charge time expires. flt does not go low if the thm thermistor tem- perature is out of range. toggle en or the input power to reset the flt indicator. power-ok indicator ( pok ) the MAX8600A contains an open-drain pok output that goes low when a valid input source is detected at dc. a valid input source is one whose voltage is between 4.1v and 6.0v and exceeds the battery volt- age by 350mv. after a valid input has been estab- lished, charging is sustained with inputs as low as 3.5v as long as the input voltage remains above the battery voltage by at least 75mv (typ). figure 2 shows pok being used to drive an external p-channel mosfet to create a node called safe dc. safe dc is an overvolt- age-protected version of dc. MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer _______________________________________________________________________________________ 7 bat thm en ct off on flt dc gnd seti pok chg MAX8600A dc input 4.1v to 6.0v led logic supply li+ c2 2.2 f t1 10k at +25 c r2 100k r3 330 d1 r seti 2k c ct 0.068 f c1 1 f + safe dc q1 d2 r1 470k figure 2. typical operating circuit. an r seti of 2k sets a maxi- mum charge current of 750ma.
MAX8600A applications information figure 2 shows the typical operating circuit for the MAX8600A. the following section describes component changes for different charging current and timer durations. charge-current selection the maximum charging current is programmed by an external resistor (r seti ) connected from seti to gnd. calculate the r seti value as follows: r seti = 1500/i charge(max) where i charge(max) is in amps and r seti is in ohms. seti can also be used to monitor the actual charge- current level. the output voltage at seti is proportional to the charging current as follows: v seti = (i charge x r seti )/1000 note that the prequal charge current (when v bat < 2.5v) operation is 10% of the fast-charge current set by r seti . also, the top-off charge-current threshold is set to 6% of the fast-charge current set by r seti . i prequal = 150/r seti i top-off = 90/r seti timer capacitor selection the MAX8600A contains timers for prequal, fast- charge, and top-off operation. these time periods are determined by the capacitance from ct to gnd. to set the charge times, calculate c ct as follows: t fastcharge = 334min x (c ct /0.068?) t prequal = 34.8min x (c ct /0.068?) t topoff = 69.6min x (c ct /0.068?) note that when thm halts charging, the timers stop and hold their value. single-input 1-cell li+ charger with ovp protection and programmable charge timer 8 _______________________________________________________________________________________ thermistor beta 3000 3250 3500 3750 resistance at +25 c 10,000 10,000 10,000 10,000 resistance at +50 c 4587.78 4299.35 4029.06 3775.75 resistance at 0 c 25,140.55 27,148.09 29,315.94 31,656.90 nominal hot trip temperature +55.14 c +52.60 c +50.46 c +48.63 c nominal cold trip temperature -3.24 c -1.26 c +0.46 c +1.97 c table 1. fault temperatures for different thermistors component function description c1 filter capacitor 1? ceramic capacitor c2 filter capacitor 2.2? ceramic capacitor c ct timing capacitor 0.068? low tc ceramic capacitor r seti dc charge-current program resistor 2k 1% (for 750ma charge) r1 pullup resistor 470k r2 pullup resistor 100k r3 led current program resistor 330 t1 negative tc thermistor phillips ntc thermistor, p/n 2322-640-63103, 10k 5% at +25? d1 charge indicator led led figure 2 external components list
battery temperature control the MAX8600A monitors battery temperature through a negative tc thermistor. select a thermistor resistance that is 10k at +25? and has a beta of 3500. the ic suspends charging when it is greater than 28.3k or less than 3.94k , which translates to a temperature limit of 0? to +50?. table 1 shows the nominal tem- perature limits that result from a wide range of available thermistor temperature curves. the curves are defined by the following equation: where is the beta term in table 1. connect thm to gnd to disable the temperature-con- trol function. when r thm disables charging, all timers pause and hold their value. capacitor selection connect a 2.2? ceramic capacitor from bat to gnd for proper stability. connect a 1f ceramic capacitor from dc to gnd. use a larger input bypass capacitor for high charging currents to reduce supply noise. all capacitors should be x5r dielectric or better. be aware that some capacitors have large voltage coefficients that reduce actual capacitance at higher operating volt- ages and should be avoided. thermal considerations the MAX8600A is in a thermally enhanced tdfn pack- age with an exposed paddle. connect the exposed pad- dle of the package to a large copper ground plane to provide a thermal contact between the device and the circuit board. the exposed paddle transfers heat away from the device, allowing the ic to charge the battery with maximum current, while minimizing the increase in die temperature. note that the MAX8600A? thermal-limit control allows the charger to be tolerant of thermally restricted pcb layouts that are sometimes unavoidable in compact portable designs. with such non-optimal lay- outs, the charger still operates, but can reduce charge current to manage temperature rise. dc input sources the MAX8600A operating input voltage range is 4.1v to 6.0v. the device survives input voltages up to 16v without damage to the ic. if the input voltage is greater than 6.5v (typ), the ic stops charging. an appropriate power supply must provide at least 4.2v plus the volt- age drop across the internal pass transistor when sourcing the desired maximum charging current. v in(min) > 4.2v + i charge(max) x r on where r on is the input-to-bat resistance (typically 0.25 ). failure to meet this requirement results in an incomplete charge or increased charge time. layout and bypassing connect the input capacitors as close as possible to the device. provide a large copper gnd plane to allow the exposed paddle to sink heat away from the device. connect the battery to bat as close as possible to the ic to provide accurate battery voltage sensing. make all high-current traces short and wide to minimize voltage drops. for an example layout, refer to the MAX8600A evaluation kit. chip information transistor count: 6838 process: bicmos rr t tce = + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 25 1 273 1 298 MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer _______________________________________________________________________________________ 9
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer 10 ______________________________________________________________________________________ 6, 8, &10l, dfn thin.eps package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . package type package code document no. 14 tdfn-ep t1433-2 21-0137
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer ______________________________________________________________________________________ 11 common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.05 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.10 mo229 / weed-3 0.40 bsc - - - - 0.200.05 2.40 ref t1433-2 14 2.300.10 1.700.10 t633-2 6 1.500.10 2.300.10 0.95 bsc mo229 / weea 0.400.05 1.90 ref t833-2 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref t833-3 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref 2.300.10 mo229 / weed-3 2.00 ref 0.250.05 0.50 bsc 1.500.10 10 t1033-2 package information (continued) for the latest package outline information and land patterns, go to www.maxim-ic.com/packages .
MAX8600A single-input 1-cell li+ charger with ovp protection and programmable charge timer maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 12 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 1/08 initial release 1 1/09 corrected various errors 1?, 6, 7

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