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LTC4059 1 4059f n wireless pdas n cellular phones n portable electronics n wireless headsets n digital cameras , ltc and lt are registered trademarks of linear technology corporation. n programmable charge current up to 900ma with 5% accuracy n charge current monitor output for charge termination* n constant-current/constant-voltage operation with thermal regulation to maximize charging rate without risk of overheating* n constant-current source mode for charging nickel batteries n no external mosfet, sense resistor or blocking diode required n operating supply voltage from 3.75v to 8v n charges single cell li-ion batteries directly from usb port n preset 4.2v charge voltage with 0.6% accuracy n 10 m a supply current in shutdown mode n tiny 6-lead (2mm 2mm) dfn package 900ma linear li-ion battery charger with thermal regulation in 2 2 dfn the ltc ? 4059 is a constant-current/constant-voltage lin- ear charger for single cell lithium-ion batteries. its 2mm 2mm dfn package and low external component count make the LTC4059 especially well suited for portable applications. furthermore, the LTC4059 is designed to work within usb power specifications. no external sense resistor, mosfet or blocking diode is required. thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient thermal conditions. the charge voltage is fixed at 4.2v and the charge current can be programmed with a resistor. when the input supply (wall adapter or usb supply) is removed, the LTC4059 automatically enters a low current state, dropping the battery current drain to less than 1 m a. with power applied, the LTC4059 can be put into shutdown mode, reducing the supply current to 10 m a. the LTC4059 can also be used as a constant current source to charge nickel cells. other features include undervoltage lockout protection and a current monitor pin which can indicate when to terminate a charge cycle. the LTC4059 is available in a 6-lead, low profile (0.8mm) 2mm 2mm dfn package. v cc LTC4059 v in 4.5v to 6.5v en li cc bat 1 f 2k 4.2v li-ion battery 600ma 4059 ta01 prog gnd + *us patent 6,522,118 complete charge cycle (800mah battery) time (hours) 0 500 600 700 2 4059 ta02 400 300 0.5 1 1.5 2.5 200 100 0 4.0 4.2 4.4 3.8 3.6 3.4 3.2 3.0 charge current (ma) battery voltage (v) constant current constant voltage v cc = 5v r prog = 2k t a = 25 c features descriptio u applicatio s u typical applicatio u
LTC4059 2 4059f input supply voltage (v cc ) ...................... C0.3v to 10v bat .......................................................... C0.3v to 10v prog, en, li cc ....................................... C0.3v to 10v bat short-circuit duration ........................... continuous bat pin current ............................................... 1000ma prog pin current ............................................. 1000 m a junction temperature .......................................... 125 c operating temperature range (note 2) .. C 40 c to 85 c storage temperature range ................. C 65 c to 125 c order part number consult ltc marketing for parts specified with wider operating temperature ranges. LTC4059edc absolute axi u rati gs w ww u package/order i for atio uu w (note 1) electrical characteristics the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25 c. v cc = 5v unless otherwise noted. t jmax = 125 c, q ja = 60 c/w to 85 c/w depending on pcb layout (note 3) exposed pad is gnd (pin 7) must be soldered to pcb symbol parameter conditions min typ max units v cc v cc supply voltage l 3.75 8 v i cc quiescent v cc supply current v bat = 4.5v (forces i bat and i prog = 0) l 25 60 m a i ccms v cc supply current in shutdown v en = v cc l 10 25 m a i ccuv v cc supply current in undervoltage v cc < v bat ; v cc = 3.5v, v bat = 4v l 410 m a lockout v float v bat regulated output voltage i bat = 2ma 4.175 4.2 4.225 v 4.5v < v cc < 8v, i bat = 2ma l 4.158 4.2 4.242 v i bat bat pin current r prog = 2.43k, current mode, v bat = 3.8v l 475 500 525 ma r prog = 12.1k, current mode, v bat = 3.8v l 94 100 106 ma i bms battery drain current in shutdown v en = v cc , v cc > v bat l 0 1 m a i buv battery drain current in undervoltage v cc < v bat , v bat = 4v l 014 m a lockout v uv v cc C v bat undervoltage lockout v cc from low to high, v bat = 3.7v l 100 150 200 mv threshold v cc from high to low, v bat = 3.7v l 03580 mv v prog prog pin voltage r prog = 2.43k, i prog = 500 m a l 1.18 1.21 1.24 v r prog = 12.1k, i prog = 100 m a l 1.18 1.21 1.24 v v ms manual shutdown threshold v en increasing l 0.3 0.92 1.2 v v mshys manual shutdown hysteresis v en decreasing 85 mv r en en pin input resistance v en = 5v l 1 1.85 3 m w v li cc voltage mode disable threshold v li cc increasing l 0.3 0.92 1.2 v v li cchys voltage mode disable hysteresis v li cc decreasing 85 mv t lim junction temperature in constant 115 c temperature mode r on power fet on resistance v li cc = 5v, i bat = 150ma 800 1200 m w (between v cc and bat) top view 7 dc6 package 6-lead (2mm 2mm) plastic dfn 4 5 6 3 2 1 gnd li cc bat en prog v cc note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: the LTC4059e is guaranteed to meet performance specifications from 0 c to 70 c. specifications over the C40 c to 85 c operating temperature range are assured by design, characterization and correlation with statistical process controls. note 3: failure to solder the exposed backside of the package to the pc board ground plane will result in a thermal resistance much higher than 60 c/w. dc6 part marking lafu
LTC4059 3 4059f typical perfor a ce characteristics uw battery regulation (float) voltage vs battery charge current i bat (ma) 0 v float (v) 4.16 4.18 4.20 300 500 4059 g01 4.14 4.12 4.10 100 200 400 4.22 4.24 4.26 v cc = 5v t a = 25 c r prog = 2.43k temperature ( c) ?0 v float (v) 4.19 4.20 4.21 25 75 4059 g02 4.18 4.17 4.16 ?5 0 50 4.22 4.23 4.24 100 v cc = 5v i bat = 2ma r prog = 2.43k v cc (v) 4 v float (v) 4.19 4.20 4.21 7 4059 g03 4.18 4.17 4.16 56 4.22 4.23 4.24 8 t a = 25 c i bat = 10ma r prog = 2.43k battery regulation (float) voltage vs temperature regulated output (float) voltage vs supply voltage charge current vs input voltage charge current vs ambient temperature with thermal regulation v cc (v) 4 0 i bat (ma) 100 200 300 400 500 600 56 78 4059 g04 v bat = 3.85v t a = 25 c thermal limiting r prog = 2.43k r prog = 12.1k charge current vs battery voltage v bat (v) 2.5 0 i bat (ma) 100 200 300 400 500 600 3 3.5 4 4.5 4059 g05 li cc = 5v li cc = 0v v cc = 5v t a = 25 c r prog = 2.43k ambient temperature ( c) ?0 i bat (ma) 400 500 600 25 75 4059 g06 300 200 ?5 0 50 100 125 100 0 r prog = 12.1k r prog = 2.43k v cc = 5v v bat = 3.85v thermal control loop in operation prog pin voltage vs temperature (constant current mode) prog pin voltage vs charge current power fet on resistance vs temperature i bat (ma) 0 1.0 1.2 1.4 400 4059 f07 0.8 0.6 100 200 300 500 0.4 0.2 0 v prog (v) v cc = 5v t a = 25 c r prog = 2.43k temperature ( c) ?0 400 r ds(on) (m ) 500 600 700 800 1000 ?5 02550 4059 g09 75 100 900 v cc = 5v li cc = 5v i bat = 100ma temperature ( c) ?0 v prog (v) 1.22 1.23 1.24 25 75 4059 g08 1.21 1.20 ?5 0 50 100 125 1.19 1.18 r prog = 12.1k r prog = 2.43k v cc = 5v v bat = 3.85v
LTC4059 4 4059f typical perfor a ce characteristics uw v cc C v bat undervoltage lockout threshold vs battery voltage en pin current vs en voltage and temperature battery drain current in uvlo vs battery voltage v bat (v) 3 v uv (mv) 300 400 500 7 4059 g10 200 100 250 350 450 150 50 0 4 5 6 8 t a = 25 c r prog = 12.1k v en (v) 0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 35 4059 g11 12 46 en ( a) t a = 100 c t a = ?0 c t a = 25 c v bat (v) 0 i buv ( a) 1.2 1.6 2.0 4 4059 g12 0.8 0.4 1.0 1.4 1.8 0.6 0.2 0 1 2 3 5 v cc = 0v t a = 25 c uvlo battery drain current vs temperature manual shutdown supply current vs temperature temperature ( c) 50 ?5 0 i buv ( a) 1.0 2.5 0 50 75 4059 g13 0.5 2.0 1.5 25 100 125 v cc = 0v v bat = 4v temperature ( c) ?0 8 10 14 25 75 4059 g14 6 4 ?5 0 50 100 125 2 0 12 i ccms ( a) v cc = 5v v en = 5v manual shutdown threshold voltage vs temperature voltage mode disable threshold voltage vs temperature temperature ( c) ?0 0.6 v ms (v) 0.7 0.8 0.9 1.0 1.2 ?5 02550 4059 f15 75 100 1.1 rising falling temperature ( c) ?0 0.6 v li cc (v) 0.7 0.8 0.9 1.0 1.2 ?5 02550 4059 f16 75 100 1.1 rising falling
LTC4059 5 4059f pi fu ctio s uuu gnd (pins 1, 7): ground/exposed pad. the exposed package pad is ground and must be soldered to the pc board for maximum heat transfer. li cc (pin 2): li-ion/constant current input pin. pulling this pin above v li cc disables voltage mode thereby pro- viding a constant current to the bat pin. this feature is useful for charging nickel chemistry batteries. tie to gnd if unused. bat (pin 3): charge current output. provides charge current to the battery and regulates the final float voltage to 4.2v. an internal precision resistor divider from this pin sets this float voltage and is disconnected in shutdown mode. v cc (pin 4): positive input supply voltage. this pin provides power to the charger. v cc can range from 3.75v to 8v. this pin should be bypassed with at least a 1 m f capacitor. when v cc is within 35mv of the bat pin voltage, the LTC4059 enters shutdown mode, dropping i bat to less than 4 m a. prog (pin 5): charge current program and charge cur- rent monitor pin. connecting a 1% resistor, r prog , to ground programs the charge current. when charging in constant-current mode, this pin servos to 1.21v. in all modes, the voltage on this pin can be used to measure the charge current using the following formula: i v r bat prog prog = 1000 en (pin 6): enable input pin. pulling this pin above the manual shutdown threshold (v ms is typically 0.92v) puts the LTC4059 in shutdown mode, thus terminating a charge cycle. in shutdown mode, the LTC4059 has less than 30 m a supply current and less than 1 m a battery drain current. enable is the default state, but the pin should be tied to gnd if unused.
LTC4059 6 4059f block diagra w 2 1,7 3 4 6 + + ma v cc m2 1 d1 d1 m1 1000 r1 r2 r3 d3 + + ca ref ta + t die 115 c 1.2v voltage reference va bat ref logic r en en d2 li cc prog gnd 4059 f01 5 figure 1
LTC4059 7 4059f operatio u the LTC4059 is a linear battery charger designed primarily for charging single cell lithium-ion batteries. featuring an internal p-channel power mosfet, the charger uses a constant-current/constant-voltage charge algorithm with programmable current. charge current can be programmed up to 900ma with a final float voltage accuracy of 0.6%. no blocking diode or external sense resistor is required; thus, the basic charger circuit requires only two external components. the li cc pin disables constant-voltage operation and turns the LTC4059 into a precision current source capable of charging nickel chemistry batteries. furthermore, the LTC4059 is designed to operate from a usb power source. an internal thermal limit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 115 c. this feature protects the LTC4059 from excessive temperature, and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the LTC4059 or external components. another benefit of the LTC4059 thermal limit is that charge current can be set according to typical, not worst-case, ambient temperatures for a given application with the assurance that the charger will auto- matically reduce the current in worst-case conditions. the charge cycle begins when the voltage at the v cc pin rises approximately 150mv above the bat pin voltage, a 1% program resistor is connected from the prog pin to ground, and the en pin is pulled below the shutdown threshold (typically 0.85v). if the bat pin voltage is below 4.2v (or the li cc pin is pulled above v li cc ) the LTC4059 will charge the battery with the programmed current. this is constant-current mode. when the bat pin approaches the final float voltage (4.2v), the LTC4059 enters constant-voltage mode and the charge current begins to decrease. to terminate the charge cycle the en should be pulled above the shutdown threshold. alternatively, reducing the input voltage below the bat pin voltage will also terminate the charge cycle. applicatio s i for atio wu uu programming charge current the charge current is programmed using a single resistor from the prog pin to ground. the battery charge current is 1000 times the current out of the prog pin. the program resistor and the charge current are calculated using the following equations: r v i i v r prog chg chg prog == 1000 121 1000 121 . , . the charge current out of the bat pin can be determined at any time by monitoring the prog pin voltage and using the following equation: i v r bat prog prog = 1000 undervoltage lockout (uvlo) an internal undervoltage lockout circuit monitors the input voltage and keeps the charger in undervoltage lockout until v cc rises approximately 150mv above the bat pin voltage. the uvlo circuit has a built-in hysteresis of 115mv. if the bat pin voltage is below approximately 2.75v, then the charger will remain in undervoltage lock- out until v cc rises above approximately 3v. during under- voltage lockout conditions, maximum battery drain cur- rent is 4 m a. shutdown mode charging can be terminated by pulling the en pin above the shutdown threshold (approximately 0.92v). in shutdown mode, the battery drain current is reduced to less than 1 m a and the supply current to 10 m a.
LTC4059 8 4059f usb and wall adapter power although the LTC4059 allows charging from a usb port, a wall adapter can also be used to charge li-ion batteries. figure 2 shows an example of how to combine wall adapter and usb power inputs. a p-channel mosfet, mp1, is used to prevent back conducting into the usb port when a wall adapter is present and schottky diode, d1, is used to prevent usb power loss through the 1k pull-down resistor. typically a wall adapter can supply significantly more current than the 500ma limited usb port. therefore, an n-channel mosfet, mn1, and an extra program resistor are used to increase the charge current to 850ma when the wall adapter is present. whichever is trying to reduce the charge current the most. the output of the other amplifier saturates low which effectively removes its loop from the system. when in constant-current mode, ca servos the voltage at the prog pin to be 1.21v. va servos its inverting input to precisely 1.21v when in constant-voltage mode and the internal resistor divider made up of r1 and r2 ensures that the battery voltage is maintained at 4.2v. the prog pin voltage gives an indication of the charge current during constant-voltage mode as discussed in the pro- gramming charge current section. transconductance amplifier, ta, limits the die tempera- ture to approximately 115 c when in constant-tempera- ture mode. ta acts in conjunction with the constant-current loop. when the die temperature exceeds approximately 115 c, ta sources current through r3. this causes ca to reduce the charge current until the prog pin voltage plus the voltage across r3 equals 1.21v. diode d3 ensures that ta does not affect the charge current when the die tem- perature is below approximately 115 c. the prog pin voltage continues to give an indication of the charge current. in typical operation, the charge cycle begins in constant- current mode with the current delivered to the battery equal to 1210v/r prog . if the power dissipation of the LTC4059 results in the junction temperature approaching 115 c, the amplifier (ta) will begin decreasing the charge current to limit the die temperature to approximately 115 c. as the battery voltage rises, the LTC4059 either returns to constant-current mode or enters constant- voltage mode straight from constant-temperature mode. regardless of mode, the voltage at the prog pin is proportional to the current delivered to the battery. power dissipation the conditions that cause the LTC4059 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the ic. for high charge currents, the LTC4059 power dissipation is approximately: p d = (v cc C v bat ) ? i bat where p d is the power dissipated, v cc is the input supply voltage, v bat is the battery voltage and i bat is the charge applicatio s i for atio wu uu bat LTC4059 3.4k 2.43k 1k mn1 mp1 5v wall adapter 850ma i chg usb power 500ma i chg i chg v cc 3 d1 4 5 li-ion battery 4059 f02 system load prog + figure 2. combining wall adapter and usb power constant current/constant voltage/ constant temperature the LTC4059 uses a unique architecture to charge a battery in a constant-current, constant-voltage and con- stant-temperature fashion. figure 1 shows a simplified block diagram of the LTC4059. three of the amplifier feedback loops shown control the constant-current, ca, constant-voltage, va, and constant-temperature, ta modes. a fourth amplifier feedback loop, ma, is used to increase the output impedance of the current source pair, m1 and m2 (note that m1 is the internal p-channel power mosfet). it ensures that the drain current of m1 is exactly 1000 times greater than the drain current of m2. amplifiers ca and va are used in separate feedback loops to force the charger into constant-current or voltage mode, respectively. diodes d1 and d2 provide priority to either the constant-current or constant-voltage loop;
LTC4059 9 4059f current. it is not necessary to perform any worst-case power dissipation scenarios because the LTC4059 will automatically reduce the charge current to maintain the die temperature at approximately 115 c. however, the approximate ambient temperature at which the thermal feedback begins to protect the ic is: t a = 115 c C p d q ja t a = 115 c C (v cc C v bat ) ? i bat ? q ja example: consider an LTC4059 operating from a 5v wall adapter providing 900ma to a 3.7v li-ion battery. the ambient temperature above which the LTC4059 will begin to reduce the 900ma charge current is approximately: t a = 115 c C (5v C 3.7v) ? (900ma) ? 50 c/w t a = 115 c C 1.17w ? 50 c/w = 115 c C 59 c t a = 56 c the LTC4059 can be used above 56 c, but the charge current will be reduced from 900ma. the approximate current at a given ambient temperature can be calculated: i ct vv bat a cc bat ja = () 115 q using the previous example with an ambient temperature of 65 c, the charge current will be reduced to approximately: i cc vv cw c ca ima bat bat = () = = 115 65 537 50 50 65 770 . / / furthermore, the voltage at the prog pin will change proportionally with the charge current as discussed in the programming charge current section. it is important to remember that LTC4059 applications do not need to be designed for worst-case thermal conditions since the ic will automatically reduce power dissipation when the junction temperature reaches approximately 115 c. board layout considerations in order to be able to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the LTC4059 package is soldered to the pc board ground. correctly soldered to a 2500mm 2 double sided 1oz copper board the LTC4059 has a thermal resistance of approximately 60 c/w. failure to make thermal contact between the exposed pad on the backside of the package and the copper board will result in thermal resistances far greater than 60 c/w. as an example, a correctly soldered LTC4059 can deliver over 900ma to a battery from a 5v supply at room temperature. without a backside thermal connection, this number could drop to less than 500ma. stability considerations the LTC4059 contains two control loops: constant voltage and constant current. the constant-voltage loop is stable without any compensation when a battery is connected with low impedance leads. excessive lead length, how- ever, may add enough series inductance to require a bypass capacitor of at least 1 m f from bat to gnd. further- more, a 4.7 m f capacitor with a 0.2 w to 1 w series resistor from bat to gnd is required to keep ripple voltage low when the battery is disconnected. high value capacitors with very low esr (especially ce- ramic) reduce the constant-voltage loop phase margin. ceramic capacitors up to 22 m f may be used in parallel with a battery, but larger ceramics should be decoupled with 0.2 w to 1 w of series resistance. in constant-current mode, the prog pin is in the feedback loop, not the battery. because of the additional pole created by prog pin capacitance, capacitance on this pin must be kept to a minimum. with no additional capaci- tance on the prog pin, the charger is stable with program resistor values as high as 12k. however, additional capaci- tance on this node reduces the maximum allowed pro- gram resistor. the pole frequency at the prog pin should be kept above 500khz. therefore, if the prog pin is loaded applicatio s i for atio wu uu
LTC4059 10 4059f with a capacitance, c prog , the following equation should be used to calculate the maximum resistance value for r prog : r c prog prog p 1 2510 5 average, rather than instantaneous, battery current may be of interest to the user. for example, if a switching power supply operating in low current mode is connected in parallel with the battery, the average current being pulled out of the bat pin is typically of more interest than the instantaneous current pulses. in such a case, a simple rc filter can be used on the prog pin to measure the average applicatio s i for atio wu uu figure 3. isolating capacitive load on prog pin and filtering battery current as shown in figure 3. a 20k resistor has been added between the prog pin and the filter capacitor to ensure stability. v cc bypass capacitor many types of capacitors can be used for input bypassing; however, caution must be exercised when using multi- layer ceramic capacitors. because of the self-resonant and high q characteristics of some types of ceramic capaci- tors, high voltage transients can be generated under some start-up conditions, such as connecting the charger input to a live power source. for more information, refer to application note 88. LTC4059 c filter charge current montior circuitry r prog 20k 4059 f03 prog gnd figure 4. photo of typical circuit (2.5mm 2.7mm) 2.5mm 2.7mm
LTC4059 11 4059f u package descriptio dc package 6-lead plastic dfn (2mm 2mm) (reference ltc dwg # 05-08-1703) 2.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (wccd-2) 2. all dimensions are in millimeters 3. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 4. exposed pad shall be solder plated 5. shaded area is only a reference for pin 1 location on the top and bottom of package 0.38 0.05 bottom view?xposed pad 0.56 0.05 (2 sides) 0.75 0.05 r = 0.115 typ 1.37 0.05 (2 sides) 1 3 6 4 pin 1 top mark (see note 5) 0.200 ref 0.00 ?0.05 (dc6) dfn 0403 0.25 0.05 1.42 0.05 (2 sides) recommended solder pad pitch and dimensions 0.61 0.05 (2 sides) 1.15 0.05 0.50 bsc 0.675 0.05 2.50 0.05 package outline 0.25 0.05 pin 1 notch 0.50 bsc information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LTC4059 12 4059f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear.com ? linear technology corporation 2003 lt/tp 1103 1k printed in usa part number description comments ltc1733 monolithic lithium-ion linear battery charger standalone charger with programmable timer, up to 1.5a charge current ltc1734 lithium-ion linear battery charger in thinsot tm simple thinsot charger, no blocking diode, no sense resistor needed ltc1998 lithium-ion low battery detector 1% accurate 2.5 m a quiescent current, sot-23 ltc4050 lithium-ion linear battery charger controller simple charger uses external fet, features preset voltages, c/10 charger detection and programmable timer, input power good indication, thermistor interface ltc4052 monolithic lithium-ion battery pulse charger no blocking diode or external power fet required ltc4053 usb compatible monolithic li-ion battery charger standalone charger with programmable timer, up to 1.25a charge current ltc4054 standalone linear li-ion battery charger thermal regulation prevents overheating, c/10 termination, with integrated pass transistor in thinsot c/10 indicator ltc4056 standalone lithium-ion linear battery charger standalone charger with programmable timer, no blocking diode, in thinsot no sense resistor needed ltc4057 monolithic lithium-ion linear battery charger no external mosfet, sense resistor or blocking diode required, with thermal regulation in thinsot charge current monitor for gas gauging ltc4410 usb power manager for simultaneous operation of usb peripheral and battery charging from usb port, keeps current drawn from usb port constant, keeps battery fresh, use with the ltc4053, ltc1733 or ltc4054 ltc4058 950ma standalone li-ion charger in 3mm 3mm usb compatible, thermal regulation protects against overheating dfn thinsot is a trademark of linear technology corporation. related parts

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