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standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 1 of 11 3h20 n rev. p001 ec4901 7 general description ec490 17 is a complete constant - current & constant voltage linear charger for single cell lithium - ion and lithium - polymer batteries. its sot 23 package and low external component count make EC49017 ideally sui ted for portable applications. furthermore, the EC49017 is specifically designed to work within usb power specification. at the same time, EC49017 can also be used in the standalone lithium - ion and lithium - polymer battery charger s . no e xternal sense resistor is needed, and no blocking diode is required due to the internal mosfet architecture. thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. the charge vo ltage is fixed at 4.2 2 v, and the charge current can be programmed externally with a single resistor.the EC49017 automatically terminates the charge cycle when the charge current drops to 1/10 th the programmed value after the final float voltage is reached. when the input supply (wall adapter or usb supply) is removed, the EC49017 automatically enters a low current stage, dropping the battery drain current to less than 2ua. the EC49017 can be put into shutdown mode, reducing the supply current to 20 ua. oth er features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage. EC49017 is intentionally designed to have slightly negative tempco. this provides ext ra protection to lithium battery during charging. features ? programmable charge current up to 800ma ? no mosfet, sense resistor or blocking diode required ? constant - current/constant - voltage operation with thermal protection to maximize charge rate without ri sk of overheating ? charges single cell li - ion batteries directly from usb port ? preset 4.22v charge voltage with 1% accuracy ? 20 a supply current in shutdown ? 2.9v trickle charge threshold ? soft - start limits inrush current ? available in 6 - lead sot23 and sop - 8(e xposed pad) packages ? rohs compliant and 100% lead pb free applications ? cellular telephones, pda, mp3 players ? charging docks and cradles ? bluetooth applications pin configuration application diagram
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 2 of 11 3h20 n rev. p001 ec4901 7 ordering information absolute maximum rating (1) parameter symbol value units input supply voltage v cc 7 v prog voltage v prog vcc+0.3 v bat voltage v bat 7 v chrg voltage v chrg 7 v bat sh ort - circuit duration continuous thermal resistance, junction - to - ambient ja 2 5 0 (sot23 - 6l) c/w 75(sop - 8 with exposed pad) bat pin current i bat 800 ma prog pin current i prog 800 ? a maximum junction temperature t j 1 25 c storage temperature t s - 65 to +1 25 c lead temperature (soldering, 10 sec) 300 c package part number marking marking information sot 23 - 6 l EC49017nnb3r 01 7 b 1. starting with character 7 , a bar on top of 7 is for production year 20 13 , and underlined 7 is for year 20 14 . the naming pattern continues with consecutive characters for later years. 2. the last character b is the week code. (a - z: 1 - 26, a - z: 27 - 52) sop - 8 (exposed pad) EC49017nnm hr 49017 lllll yywwt 1. lllll lot no. 2. yyww date code 3. t internal tracking code
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 3 of 11 3h20 n rev. p001 ec4901 7 operating rating (2) parameter symbol value units supply input voltage v in - 0.3 to + 7 v junction temperature t j - 40 to + 8 5 c electrical characteristics v in = 5 v; t j = 25c; unless othe rwise specified . symbol parameter conditions min typ max unit v cc input supply voltage 3. 5 cc input supply current charge mode (3) , r prog = 10k 110 500 a standby mode (charge terminated) 70 prog not connected, v cc < v bat , or v cc < v uv ) 20 40 a v float regulated output (float) voltage i bat = 3 0ma , i chrg = 5ma 4.15 4.2 2 4.3 v i bat bat pin current r prog = 10k, current mode 90 106 130 ma r prog = 2k, current mode prog not c onnected) cc = 0v trikl trickle charge c urrent v bat < v trikl , r prog = 10 k trikl trickle charge threshold voltage r prog = 10k, v bat rising 2.8 2.9 3.0 v v uv v cc undervoltage lockout threshold from v cc low to high 3.4 v v uvhys v cc undervoltage lockout hysteresis 100 mv v msd manual shutdown threshold voltage prog pin rising 1.25 v prog pin falling 1.2 v v asd v cc C bat lockout threshold v oltage v cc from low to high 100 mv v cc from high to low 30 mv i term c/10 termination current threshold r prog = 10k (4) 10. 5 ma r prog = 2k 52 ma
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 4 of 11 3h20 n rev. p001 ec4901 7 electrical characteristics v in = 5 v; t j = 25c; unless otherwise specified . s ymbol parameter conditions min typ max unit v prog prog pin voltage r prog = 10k, current mode 0.9 1.03 1.1 v v chrg chrg pin output low voltage i chrg = 5ma 0.6 rechrg recharge battery threshold voltage v float - v rechrg 100 mv t lim thermal pro tection temperature 120 c t ss soft - start time i bat = 0 to 1 0 00v/r prog 100 s t recharge recharge comparator filter time v bat high to low 1 ms t term termination comparator filter time i bat falling below i chg /10 1000 s i prog prog pin pu ll - up current 1 a note 1: exceeding the absolute maximum rating may damage the device. note 2 : the device is not guaranteed to function outside its operating rating. note 3 : supply current includes prog pin current (approximately 100a) but does not include any current delivered to the battery through the bat pin (approximately 100ma). note 4: i term is expressed as a fraction of measured full charge current with indicated prog resistor. pin functions pin pin function description pin pin functi on description vcc positive input supply voltage . provides power to charger. vcc can range from 3.5 to 6.5v and should be bypassed w ith at least a 1uf capacitor. chrg open - drain charge status output. when the battery is charging, the chrg pin is pulled low by an internal n - channel mosfet. when the charge cycle is completed, a weak pull - down of approximately 20ua is connected to the chrg pin, indicating an open - drain charge termination status output. when the battery is charging, the chrgt pin is pulled high by an external compenent such as an led. after the charging is completed, this pin is pulled low by internal n - channel mosfet and it can be used as a charging termination indicator.
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 5 of 11 3h20 n rev. p001 ec4901 7 block diagram
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 6 of 11 3h20 n rev. p001 ec4901 7 typical performance cha racteristics float voltage vs supply voltage 4.185 4.190 4.195 4.200 4.205 4.210 4.215 4.220 4.225 4.230 4.0 4.5 5.0 5.5 6.0 6.5 v cc (v) v bat (v) r prog =10k t a =25 charge current vs supply voltage 0 100 200 300 400 500 600 4.0 4.5 5.0 5.5 6.0 6.5 7.0 v cc (v) i bat (ma) r prog =2k r prog =10k v bat = 4 v t a =25 onset of thermal regulation trickle charge current vs supply voltage 0 10 20 30 40 50 60 70 4.0 4.5 5.0 5.5 6.0 6.5 7.0 v cc (v) i trikl (ma) r prog =2k v bat =2.5v t a =25 r prog =10k float voltage vs temperature 4.185 4.190 4.195 4.200 4.205 4.210 4.215 20 40 60 80 100 120 temperature ( ) v float (v)
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 7 of 11 3h20 n rev. p001 ec4901 7 operation the ec4901 7 is a single cell lithium - ion battery charger using a constant - current/constant - voltage algorithm. it can deliver up to 800ma of charge current (using a good thermal pcb layout) with a final float voltage accuracy of 1 %. the e c4901 7 includes an internal p - channel power mosfet and thermal regulation circuitry. no blocking diode or external current sense resist or is required; thus, the basic charger circuit requires only two external comp onents. furthermore, the ec4901 7 is capable of operating from a usb power source. normal charge cycle a charge cycle begins when the voltage at the vcc pin rises above the uvlo threshold level and a 1% program resistor is connected from the prog pin to ground or when a battery is connected to the char ger output. if the bat pin is less than 2. 8 v, the charger enters trickle charge mode. in this mode, the ec4901 7 supplies approximately 1/10 the programmed charge current to bring the battery voltage up to a safe level for full current charging. when the b at pin voltage rises above 2. 8 v, the charger enters constant - current mode, where the programmed charge current is supplied to the battery. when the bat pin approaches the final float voltage (4.2 2 v), the ec4901 7 enters constant - voltage mode and the charge current begins to decrease. when the charge current drops to 1/10 of the programmed value, the charge cycle ends. programming charge current the charge current is programmed using a single resistor from the prog pin to ground. the battery charge current i s 1 060 times the current out of the prog pin. the program resistor and the charge current are calculated using the following equations: , the charge current out of the bat pin can be determined at any time by monitoring the prog pin voltage using the following equation: this actual current will vary from ic to ic. the typical variation is within +/ - 20%. charge termination a charge cycle is terminated when the charge current falls to 1/10 th the programmed value after the final float voltage is reached. this condition is detected by using an internal, filtered comparator to monitor the prog pin. when the prog pin voltage falls below 100mv for longer than t term (typically 1ms), charging is t erminated. the charge current is latched off and the ec4901 7 enters standby mode, where the input supply current drops to 200ma. (note: c/10 termination is disabled in trickle charging and thermal limiting modes).when charging, transient loads on the bat p in can cause the prog pin to fall below 100mv for short periods of time before the dc charge current has dropped to 1/10th the programmed value. the 1ms filter time (t term ) on the termination comparator ensures that transient loads of this nature do not re sult in premature charge cycle termination. once the average charge current drops below 1/10th the programmed value, the ec4901 7 terminates the charge cycle and ceases to provide any current through the bat pin. in this state, all loads on the bat pin must be supplied by the battery. the ec4901 7 constantly monitors the bat pin voltage in standby mode. if this voltage drops below the 4.05v recharge threshold (v rechrg ), another charge cycle begins and current is once again supplied to the battery. to manually restart a charge cycle when in standby mode, the prog chg chg prog r v i i v r 1060 , 1060 ? ? 1060 ? ? prog prog bat r v i
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 8 of 11 3h20 n rev. p001 ec4901 7 input voltage must be removed and reapplied, or the charger must be shut down and restarted using the prog pin. figure 1 shows the state diagram of a typical charge cycle. charge status indicator (chrg) ch rg pin and chrgt pin indicates different charge states. w hen ec4 9017 is in a charge cycle , chrg pin is pull - down (~10ma), and chrgt pin is high impedance. once the charge cycle has terminated, the chrg pin is high impedance and chrgt pin is pull - down. th ermal limiting an internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 120 . this feature protects the ec4901 7 from excessive temperature and allows the user to p ush the limits of the power handling capability of a given circuit board without risk of damaging the ec4901 7 . the charge current can be set according to typical (not worst - case) ambient temperature with the assurance that the charger will automatically re duce the current in worst - case conditions. undervoltage lockout (uvlo) an internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until vcc rises above the undervoltage lockout threshold. the uvlo circuit h as a built - in hysteresis of 200mv. furthermore, to protect against reverse current in the power mosfet, the uvlo circuit keeps the charger in shutdown mode if vcc falls to within 30mv of the battery voltage. if the uvlo comparator is tripped, the charger w ill not come out of shutdown mode until vcc raises 100mv above the battery voltage. figure 1. state diagram of a typical charge cycle
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 9 of 11 3h20 n rev. p001 ec4901 7 stability considerations the constant - voltage mode feedback loop is stable without an output capacitor provided a ba ttery is connected to the charger output. with no battery present, an output capacitor is recommended to reduce ripple voltage. when using high value, low esr ceramic capacitors, it is recom mended to add a 1 resistor in series with the capacitor. no serie s resistor is needed if tantalum capacitors are used. in constant - current mode, the prog pin is in the feedback loop, not the battery. the constant - current mode stability is affected by the impedance at the prog pin. with no additional capacitance on the prog pin, the charger is stable with program resistor values as high as 20k. however, additional capacitance on this node reduces the maximum allowed program resistor. the pole frequency at the prog pin should be kept above 100khz. v cc bypass capacitor m any 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 capacitors, high voltage transients can b e generated under some start - up conditions, such as connecting the charger input to a live power source. adding a 1.5 resistor in series with a ceramic capacitor will minimize start - up voltage transients. power dissipation the conditions that cause the ec4 901 7 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the ic. nearly all of this power dissipation is generated by the internal mosfet this is calculated to be approximately: p d = (v cc C v bat ) ? i bat the approximate ambient temperature at which the thermal feedback begins to protect the ic is: t a = 120c C p d ja t a = 120c C (v cc C v bat ) ? i bat ? ja thermal considerations because of the small size of the thin sot23 package, it is very important to use a good thermal pc board layout to maximize the available charge current. the thermal path for the heat gene rated by the ic is from the die to the copper lead frame, through the package lead, (especially the ground lead) to the pc board copper. the pc board copper is the heat sink. the footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. other heat sources on the board, not related to the charger, must also be considered when designing a pc board layout because they will affect overall temperature rise and the maximu m charge current. application hints
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 10 of 11 3h20 n rev. p001 ec4901 7 no - load indications put a 1uf capacitor between bat and gnd . this makes up of a no - load indications circuit as shown below. if there is not a battery connected to bat and gnd of ec490 17 then we can see that led - r will be flashing at 2.5 hz/s. if there is a battery connected to bat and gnd pin of ec490 17. th en ec490 17 enters normal charging cycle.
standalone linear lithium battery charger e - cmos corp. ( www.ecmos.com.tw ) page 11 of 11 3h20 n rev. p001 ec4901 7 outline drawing sot23 - 6 l outline drawing sop - 8(exposed pad)

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