general description the max1551/max1555 charge a single-cell lithium-ion (li+) battery from both usb and ac adapter sources. they operate with no external fets or diodes, and accept operating input voltages up to 7v. on-chip thermal limiting simplifies pc board layout and allows optimum charging rate without the thermal limits imposed by worst-case battery and input voltage. when the max1551/max1555 thermal limits are reached, the chargers do not shut down, but progressively reduce charging current. the max1551 includes a pok output to indicate when input power is present. if either charging source is active, pok goes low. the max1555 instead features a chg output to indicate charging status. with usb connected, but without dc power, charge cur- rent is set to 100ma (max). this allows charging from both powered and unpowered usb hubs with no port communication required. when dc power is connected, charging current is set at 280ma (typ). no input-blocking diodes are required to prevent battery drain. the max1551/max1555 are available in 5-pin thin sot23 packages and operate over a -40? to +85? range. applications pdas wireless appliances cell phones digital cameras features ? charge from usb or ac adapter ? automatic switchover when ac adapter is plugged in ? on-chip thermal limiting simplifies board design ? charge status indicator ? 5-pin thin sot23 package sot23 dual-input usb/ac adapter 1-cell li+ battery chargers ordering information 19-2902; rev 0; 7/03 part temp range pin-package max1551 ezk-t -40? to +85? 5 thin sot23-5 max1555 ezk-t -40? to +85? 5 thin sot23-5 gnd dc 15 bat usb max1551 (max1555) thin sot23 top view 2 34 pok (chg) pin configuration max1551 (max1555) dc usb bat ac adapter 3.7v to 7v usb 3.7v to 6v to system load li+ gnd to logic rail charge control pok (chg) logic control typical operating circuit selector guide part top mark features MAX1551EZK adrt pok output max1555ezk adru chg output functional diagrams pin configurations appear at end of data sheet. functional diagrams continued at end of data sheet. ucsp is a trademark of maxim integrated products, inc. available for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim?s website at www.maxim integrated.com. max1551/max1555
sot23 dual-input usb/ac adapter 1-cell li+ battery chargers absolute maximum ratings electrical characteristics (v dc = 5v, v usb = 0, i bat = 0, c bat = 1f, t a = 0? to +85?, unless otherwise noted.) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. dc to gnd......................................................................0 to +8v dc to bat .......................................................................0 to +7v bat, chg, pok , usb to gnd .................................-0.3v to +7v continuous power dissipation (t a = +70c) 5-pin thin sot23 (derate 9.1mw/ c above +70 c) ....727mw operating temperature range ...........................-40 c to +85c junction temperature range ............................-40 c to +150c storage temperature range .............................-65 c to +150c lead temperature (soldering, 10s) .................................+300 c parameter conditions min typ max units dc dc voltage range (note 1) 3.7 7.0 v dc to bat voltage range 0.1 6.0 v dc undervoltage lockout threshold input rising, 430mv hysteresis, v bat = 3v (note 1) 3.75 3.95 4.15 v dc supply current 1.75 3 ma dc to bat on-resistance v dc = 3.7v, v bat = 3.6v 1 2 ? dc to bat dropout voltage when charging stops, v bat = 4v, dc falling, 200mv hysteresis 30 60 90 mv usb usb voltage range (note 1) 3.7 6.0 v usb undervoltage threshold input rising, 430mv hysteresis, v dc = 0, v bat = 3v (note 1) 3.75 3.95 4.15 v usb supply current v usb = 5v, v dc = 0 1.65 3 ma usb to bat on-resistance v usb = 3.7v, v bat = 3.6v, v dc = 0 2 4 ? usb to bat dropout voltage when charging stops, v bat = 4v, usb falling, 200mv hysteresis, v dc = 0 30 60 90 mv bat bat regulation voltage v dc or v usb = 5v 4.158 4.2 4.242 v dc charging current v bat = 3.3v, v usb = 0, v dc = 5v 220 280 340 ma usb charging current v bat = 3.3v, v dc = 0, v usb = 5v 80 90 100 ma bat prequal threshold v bat rising, 100mv hysteresis 2.9 3 3.1 v prequalification charging current v bat = 2.8v 20 40 80 ma bat leakage current v dc = v usb = 0, v bat = 4.2v 5 a pok , chg, and thermal limit chg threshold charge current where chg goes high, i bat falling, 50ma hysteresis 25 50 100 ma chg, pok logic-low output i chg , i pok = 10ma 150 300 mv chg, pok leakage current v chg , v pok = 6v, t a = +25 c 0.001 1 a thermal-limit temperature charge current reduced by 17ma/ c above this temperature +110 c max1551/max1555 2 maxim integrated
sot23 dual-input usb/ac adapter 1-cell li+ battery chargers note 1: the input undervoltage lockout has 430mv of hysteresis. the charger turns on when an input rises to 3.95v (typ), and turns off when it falls below 3.52v. note 2: specifications to -40c are guaranteed by design, not production tested. electrical characteristics (v dc = 5v, v usb = 0, i bat = 0, c bat = 1f, t a = -40 c to +85 c, unless otherwise noted.) (note 2) parameter conditions min max units dc dc voltage range (note 1) 3.7 7.0 v dc to bat voltage range 0.1 6.0 v dc undervoltage lockout threshold input rising, 430mv hysteresis, v bat = 3v (note 1) 3.75 4.15 v dc supply current 3ma dc to bat on-resistance v dc = 3.7v, v bat = 3.6v 2 ? dc to bat dropout voltage when charging stops, v bat = 4v, dc falling, 200mv hysteresis 30 95 mv usb usb voltage range (note 1) 3.7 6.0 v usb undervoltage lockout threshold input rising, 430mv hysteresis, v dc = 0, v bat = 3v (note 1) 3.75 4.15 v usb supply current v usb = 5v, v dc = 0 3 ma usb to bat on-resistance v usb = 3.7v, v bat = 3.6v, v dc = 0 4 ? usb to bat dropout voltage when charging stops, v bat = 4v, usb falling, 200mv hysteresis, v dc = 0 30 95 mv bat bat regulation voltage v dc or v usb = 5v 4.141 4.259 v dc charging current v bat = 3.3v, v usb = 0, v dc = 5v 220 340 ma usb charging current v bat = 3.3v, v dc = 0, v usb = 5v 80 100 ma bat prequal threshold v bat rising, 100mv hysteresis 2.9 3.1 v prequalification charging current v bat = 2.8v 20 80 ma bat leakage current v dc = v usb = 0, v bat = 4.2v 5 a pok , chg chg threshold charge current where chg goes high, i bat falling, 50ma hysteresis 25 100 ma chg, pok logic-low output i chg , i pok = 10ma 300 mv chg, pok leakage current v chg , v pok = 6v, t a = +25 c1 a max1551/max1555 maxim integrated 3
sot23 dual-input usb/ac adapter 1-cell li+ battery chargers typical operating characteristics (v dc = 5v, v usb = 0, i bat = 0, c bat = 1f, t a = +25c, unless otherwise noted.) charge current vs. dc voltage headroom max1551/55 toc01 dc voltage headroom (v dc - v bat ) (v) charge current (ma) 0.30.20.1 0 50 100 150 200 250 300 -50 00 . 5 0.4 v bat = 3.8v, v dc falling charge current vs. usb voltage headroom max1551/55 toc02 usb voltage headroom (v usb - v bat ) (v) charge current (ma) 0.4 0.3 0.2 0.1 0 20 40 60 80 100 -20 00 . 5 v dc = 0, v bat = 3.8v, v usb falling dc charge current vs. battery voltage max1551/55 toc03 battery voltage (v) dc charge current (ma) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 50 100 150 200 250 300 -50 04 . 5 usb charge current vs. battery voltage max1551/55 toc04 battery voltage (v) usb charge current (ma) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 20 40 60 80 100 -20 04 . 5 dc charge current vs. ambient temperature max1551/55 toc05 temperature (c) dc charge current (ma) 75 65 55 45 35 0 50 100 150 200 250 300 -50 25 85 v bat = 3.8v, v dc = 5v thermal limit activated battery termination voltage vs. temperature max1551/55 toc06 temperature (c) battery termination voltage (v) 35 60 10-15 4.19 4.20 4.21 4.22 4.18 -40 85 bat open off-battery leakage current vs. dc input voltage max1551/55 toc07 dc or usb input voltage (v) off-battery leakage current ( a) 4 3 2 1 0.5 1.0 1.5 2.0 2.5 0 05 v dc = 0, sweeping usb 0 to 5v or v usb = 0, sweeping dc 0 to 5v v bat = 4.2v usb-to-dc transition waveform max1551/55 toc08 400ms/div v usb 5v/div v dc 5v/div 0a 0v 0v 0v battery current 200ma/div v pok 2v/div max1551/max1555 4 maxim integrated
detailed description the max1551/max1555 charge a single-cell li+ bat- tery from both usb and ac adapter sources, enabling portable users to forgo carrying a wall cube. these devices operate with no external fets or diodes, and accept operating input voltages up to 7v. an internal thermal control loop simplifies pc board lay- out and allows optimum charging rate without the ther- mal limits imposed by worst-case battery and input voltage. when the max1551/max1555 thermal limits are reached, the chargers do not shut down, but simply reduce charging current by 17ma/ c above a die tem- perature of +110c. with usb connected, but without dc power, the charge current is set to 100ma (max). this allows charging from both powered and unpowered usb hubs with no port communication required. when dc power is con- nected, charging current is set at 280ma (typ). the max1551/max1555 do not feature an enable input. once power is connected to usb and/or dc, the charger is on. when input power is removed, battery leakage current is less than 5a. no input-blocking diodes are required to prevent battery drain. insert a diode at dc (the adapter input) if protection from negative voltage inputs (reversed-polarity adapter plugs) is required. usb to adapter power handoff the max1551/max1555 can charge from either the usb input or the dc input. the battery does not charge from both sources at the same time. the max1551/ max1555 automatically detect the active input and charge from that. if both power sources are active, the dc input takes precedence. the switchover between dc and usb is detailed in table 1. max1551 power-ok ( pok ) the max1551 s pok is an active-low, open-drain out- put that goes low when v dc or v usb is above 3.95v. pok can be used as a logic output or can drive an led. pok indicates the charger is connected to input power and is charging. max1555 charge status ( chg ) the max1555 s chg is an active-low, open-drain charge status indicator. chg pulls low when the battery is charging (whenever usb or dc are powered) and charge current is greater than 50ma. chg indicates when the battery is fully charged by going high imped- ance when the charger is in voltage mode and charge current falls below 50ma. charging does not stop when chg goes high. chg is low in precharge mode. sot23 dual-input usb/ac adapter 1-cell li+ battery chargers pin description pin name function 1 usb usb port charger supply input. usb draws up to 100ma to charge the battery. decouple usb with a 1f ceramic capacitor to gnd. 2 gnd ground pok power-ok active-low open-drain charger status indicator. pok pulls low when either charger source is present (max1551 only). 3 chg active-low open-drain charge status indicator. chg pulls low when the battery is charging. chg goes to a high-impedance state, indicating the battery is fully charged, when the charger is in voltage mode and charge current falls below 50ma. chg is high impedance when both input sources are low (max1555 only). 4dc dc charger supply input for an ac adapter. dc draws 280ma to charge the battery. decouple dc with a 1f ceramic capacitor to gnd. 5 bat battery connection. decouple bat with a 1f ceramic capacitor to gnd. v dc > 7v or v usb > 6v v dc > 3.95v and v usb don ?t care v dc < 3.52v and 3.95v < v usb < 6v v dc and v usb < 3.52v exceeds operating input range. not allowed. see the absolute maximum ratings section. 280ma (typ) charging from dc 100ma (max) charging from usb undervoltage lockout table 1. usb and dc input selection (v dc takes precedence when both inputs are present.) max1551/max1555 maxim integrated 5
precharge current the max1551/max1555 feature a precharge current to protect deeply discharged cells. if v bat is less than 3v, the device enters precharge mode where charging cur- rent is limited to 40ma. package thermal limiting on-chip thermal limiting in the max1551/max1555 sim- plifies pc board layout and allows charging rates to be optimized without the limits imposed by worst-case bat- tery and input voltages. the device reduces the power dissipation at bat to prevent overheating. this allows the board design to be optimized for compact size and typical thermal conditions. when the max1551/ max1555 thermal limits are reached, the chargers do not shut down, but progressively reduce charging cur- rent by 17ma/ c above a die temperature of +110 c. solder the max1551/max1555s gnd to a large ground plane to help dissipate power and keep the die temperature below the thermal limit. the usb charge current of 100ma is unlikely to induce thermal limiting. bypass capacitors use ceramic bypass capacitors at dc, usb, and bat. mount these capacitors within 1cm of their respective pins. x7r and x5r dielectrics are recommended. chip information transistor count: 541 process: bicmos sot23 dual-input usb/ac adapter 1-cell li+ battery chargers max1551 (max1555) dc usb bat ac adapter 3.7v to 7v usb 3.7v to 6v to system load li+ gnd to logic rail charge control pok (chg) logic control c1 1f c2 1f c3 1f r1 100k? indicates that power is present (either dc or usb) typical application circuit max1551/max1555 6 maxim integrated
sot23 dual-input usb/ac adapter 1-cell li+ battery chargers package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) max1551/max1555 maxim integrated 7
sot23 dual-input usb/ac adapter 1-cell li+ battery chargers package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) max1551/max1555 8 maxim integrated 160 rio robles, san jose, ca 95134 usa 1-408-601-1000 maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. ? 2003 maxim integrated the maxim logo and maxim integrated are trademarks of maxim integrated products, inc.
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