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unisonic technologies co., ltd ub2012 preliminary linear integrated circuit www.unisonic.com.tw 1 of 17 copyright ? 2010 unisonic technologies co., ltd qw-r121-018.b advanced linear charge management ic for single and two-cell lithium-ion and lithium-polymer ? description utc ub2012 is designed for portable electronics with lower cost. its advantages of high-accuracy voltage/current regulation, charging status indication, temperature monitoring, and automatic charge-rate compensation. in applications, the battery temperat ure is continuously under monitor by using an external thermistor, if the temperature is over user-defined threshold; utc ub2012 inhibits charge for safety concern. generally, the ub2012 charges the battery in conditioning, constant voltage and constant current phases. if the battery voltage is lower than the low-voltage threshold (v min ), a low current is used for conditioning the battery. the conditioning charge rate is around 10% of the regulatio n current and the heat dissipat ion in the external pass element during the initial stage of the charge is minimized by the conditioning current. after the conditioning phase, the ub2012 applies a constant current that be set by an external sense-resistor to the battery. the sense-resistor can be on the battery without additional components. the c onstant current phase continue s until the battery reaches the charge-regulation voltage, then the c onstant voltage phase is beginning. utc ub2012 offers 4.1v, 4.2v, 8.4v and 8.4v fixed-volt age for single and dual cells. charge stops when the current tapers to the charge termination threshold (i term ) and will recharge if the battery voltage falls below the v rch . the automatic charge-rate compensati on feature reduces the charging time of batteries. for the internal impedance of battery pack during charge, this advanced technique offers safe and dynamic compensation. ? features * ideal for single 4.1v,4.2 v and dual-cell 8.2,8.4 v li-ion or li-pol packs * 0.3v dropout voltage for minimizing heat dissipation * better than 1% accuracy of voltage regulation with preset voltages * dynamic compensation of battery pack?s internal impedance to short charging time * optional cell-temperature monitoring * integrated voltage and current regulati on with programmable charge-current * integrated cell conditioning for reviving deeply dischar ged cells and minimizing heat dissipation during initial charge stage * charge status output for single or dual led or host processor interface * automatic battery-recharge feature * charge termination by minimum current * automatic low-power sleep mode when v cc is removed * evms available for quick evaluation ? ordering information ordering number package packing UB2012XG-S08-R sop-8 tape reel note: x: output voltage, re fer to marking information.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 2 of 17 www.unisonic.com.tw qw-r121-018 .b ? marking information package voltage code marking sop-8 a: 4.1v b: 4.2v c: 8.2v d: 8.4v ? pin configuration ? pin description pin no. pin name i/o pin description 1 sns i current sense input 2 bat i voltage sense input 3 v cc i supply voltage 4 ts i temperature sense input 5 stat o charge status output 6 v ss ground 7 cc o charge control output 8 comp i charge-rate compensation input (auto comp)
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 3 of 17 www.unisonic.com.tw qw-r121-018 .b ? block diagram v cc v(bat) v(bat) v(bat) v(bat) vo(reg) v(ts) v(ts) vcc comp ts v(ts) sns v(sns) v(sns) v(sns) vcc-v(sns) vss-v(sns) control logic vcc current regulation voltage termination vcc/2 ts2 ts1 high/low sns set battery conditioning battery recharge voltage regulation sleep mode g(comp) reference vo(reg) v ss stat cc driver driver driver
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 4 of 17 www.unisonic.com.tw qw-r121-018 .b ? absolute maximum rating parameter symbol ratings unit supply voltage (v cc with respect to gnd) v cc -0.3 ~ +15 v input voltage, sns, bat,ts, comp (all with respect to gnd) v in -0.3 ~ v cc +0.3 v sink current (note 2) stat pin i sink 20 ma source current (note 2) stat pin i source 10 ma output current (note 2) cc pin i out 40 ma power dissipation (ta=25c) p d 300 mw operating temperature t opr -20 ~ +70 c storage temperature t stg -40 ~ +125 c notes: 1. absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. 2. not to exceed p d . ? recommended operating conditions parameter symbol min typ max units supply voltage v cc 4.5 12 v operating free-air temperature range t a -20 70 c ? electrical characteristics parameter symbol conditions min typ max units v cc current i (vcc) v cc > v cc(min) , excluding external loads 2 5 ma ub2012a ub2012b 3 6 a ub2012c v cc sleep current i (vccs) v (bat) v (min) v (bat) - v cc 0.8v ub2012d 10 a bat pin i ib(bat) v (bat) =v (reg) 1 a sns pin i ib(sns) v (sns) =5v 5 a ts pin i ib(ts) v (ts) =5v 5 a input bias current comp pin i ib(comp) v (comp) =5v 5 a battery voltage regulation ub2012a 4.050 4.10 4.150 v ub2012b 4.150 4.20 4.250 v ub2012c 8.100 8.20 8.300 v output voltage v o(reg) see notes ub2012d 8.300 8.40 8.500 v current regulation ub2012a ub2012b 80 100 120 mv ub2012c current regulation threshold v (sns) current sensing configuration ub2012d 105 125 145 mv charge termination detection charge termination current detect threshold i (term) voltage at pin sns, 0c ta 50c -24 -14 -4 mv
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 5 of 17 www.unisonic.com.tw qw-r121-018 .b ? electrical characteristics temperature comparator lower v (ts1) 29.1 30 30.9 %v cc temperature threshold upper v (ts2) ts pin voltage 58.3 60 61.8 %v cc precharge comparator ub2012a 2.94 3.0 3.06 v ub2012b 3.04 3.1 3.16 v ub2012c 5.98 6.1 6.22 v precharge threshold v (min) ub2012d 6.18 6.3 6.42 v precharge current regulation voltage at pin sns, 0c ta 50c 13 mv precharge current regulation i (prechg) voltage at pin sns, 0c ta 50c, v cc = 5 v 3 13 22 mv v rch comparator (battery recharge threshold) ub2012a ub2012b v o(reg) -80mv v o(reg - -100mv v o(reg) -120mv v ub2012c recharge threshold v (rch) ub2012d v o(reg) -160mv v o(reg) -200mv v o(reg) -240mv v charge-rate compensation (autom atic charge-rate compensation) automatic charge-rate compensation gain g (comp) v (bat) +0.3v v cc v cc(max), 1.7 2.2 2.7 v/v stat pin output (low) voltage v ol(stat) i ol =10ma 0.7 v output (high) voltage v oh(stat) i oh =5ma v cc -0.5 v cc pin output low voltage v ol(cc) i o(cc) =5ma (sink) 1.5 v sink current i o(cc) not to exceed power rating (p d ) 5 40 ma notes: v (bat) +0.3 v v cc v cc(max)
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 6 of 17 www.unisonic.com.tw qw-r121-018 .b ? typical application circuit ub2012 gnd c2 10 f vss vcc sns cc bat stat ts comp r1 1k ? r sns 0.2 ? dc+ q1 2sb1151 v cc c1 0.1 f v cc r t1 temp pack- pack+ r t2 r2 2k ? d1 battery pack ntc figure 1. low dropout single-or two-cell li-lon/li-pol charger functional description the utc ub2012 is designed for the applications of single or tw o-cell li-ion or li-pol batteries. figure 1 is the schematic of using this advanced li near charge controller with a pnp pass transistor. figure 2 is the operation flowchart of ub2012 . figure 3 shows the typical charge profile. figur e 4 is the application schematic of a charger using p-channel mosfet..
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 7 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information figure 2. operation flowchart por v cc >v (bat) checked at all times yes ts pin in ts1 to ts2 range yes v (bat) ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 8 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) qualification and precharge when the battery is present and power is applied, the utc ub2012 starts a charge-cycl e. charge qualification is affected by battery temperature and voltage. if the battery temperat ure is out of the v ts1 to v ts2 range; the ub2012 will suspend charge. in addition, if the battery voltage is below the precharge threshold v (min) , the ub2012 uses precharge to condition the battery. the conditioning charge rate i (prechg) is set at approximately 10% of the regulation current, and the conditioning current minimizes heat dissipation in the external pass-element during the beginning of charge, refer to figure 3.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 9 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) current regulation phase when the battery-pack voltage is le ss than the regulation voltage, v o(reg) , the current is regulated by the utc ub2012 . this advanced linear charge management ic monitors charge current at the sns input by the voltage drop across a sense-resistor, r sns , in series with the battery pack. in current sensing configuration (figure 5), r sns is between the vcc and sns pins. charge-current feedback, applied through pin sns, maintains a voltage of v sns across the current sense resistor. the following formu la calculates the value of the sense resistor: o(reg) (sns) sns i v r = (1) where i o(reg) is the desired charging current.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 10 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) voltage regulation phase the voltage regulation feedback is through the bat pin. this input is tied directly to the positive side of the battery pack. the utc ub2012 monitors the battery-pack voltage between the bat and vss pins. according to the voltage regulation, there ar e four versions of utc ub2012 , namely, 4.1 v, 4.2 v, 8.2 v and 8.4 v. other regulation voltages can be ac hieved by adding a voltage divide r between the positive and negative terminals of the battery pack and using utc ub2012 c or utc ub2012 d. the voltage divider presents scaled battery-pack voltage to bat input. (see figure 7 and figure 8) the resistor values rb1 and rb2 for the voltage divider are calculated by the following equation: 1 - ) v v (n = r r o(reg) (cell) b2 b1 (2) where: n = number of cells in series, v (cell) = desired regulation voltage per cell charge termination and recharge the utc ub2012 monitors the charging current durin g the voltage-regulation phase. the utc ub2012 declares a done condition and terminates charge when the current tapers off to the charge termination threshold, i (term) . a new charge cycle begins when the battery voltage falls below the v (rch) threshold.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 11 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) battery temperature monitoring the utc ub2012 continuously monitors temperature by meas uring the voltage between the ts and vss pins. a negative- or a positive-temperature co efficient thermistor (ntc, ptc) and an external voltage divider typically develop this voltage. (see figure 9.) the utc ub2012 compares this voltage against its internal v (ts1) and v (ts2) thresholds to determine if charging is allowed. (see fi gure 10.) the temperature sensing circuit is immune to any fluctuation in v cc , since both the external voltage divider and the internal thresholds (v (ts1) and v (ts2) ) are referenced to v cc . the resistor values of r (t1) and r (t2) are calculated by the following equations: for ntc thermistors: ) r r ( 3 r r 5 = r th tc tc th 1 t - (3) )] r 7 ( - ) r 2 [( r r 5 = r th tc tc th 2 t (4) for ptc thermistors: ) r r ( 3 r r 5 = r tc th tc th 1 t - (5) )] r 7 ( - ) r 2 [( r r 5 = r tc th tc th 2 t (6) where r (tc) is the cold temperature resistance and r (th) is the hot temperature re sistance of thermistor, as specified by the thermistor manufacturer. r t1 or r t2 can be omitted if only one temperat ure (hot or cold) setting is requi red. applying a voltage between the v (ts1) and v (ts2) thresholds to pin ts disables the temperature-sensing feature. utc ub2012 sns bat v cc ts stat v ss cc comp bat- bat+ r sns dc+ dc- r t1 r t2 thermistor figure 7. temperature sensing circuits figure 8. utc ub2012 ts input thresholds
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 12 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) charge inhibit function the ts pin can be used as charge-inhibit input. the user can inhibit charge by connecting the ts pin to vcc or vss (or any level outside the v (ts1) to v (ts2) thresholds). applying a voltage between the v (ts1) and v (ts2) thresholds to pin ts returns the charger to normal operation. charge status indication the utc ub2012 reports the status of the char ger on the 3-state stat pin. t he following table summarized the operation of the stat pin. condition stat pin battery conditioning and charging high charge complete (done) low temperature fault or sleep mode hi-z the stat pin can be used to drive a single led (figure 1) , dual-chip leds (figure 4) or for interface to a host or system processor (figure 11). when interfacing the utc ub2012 to a processor, the us er can use an output port, as shown in figure 11, to recognize the high-z state of the stat pin. in this configuration, the user needs to read the input pin, toggle the out put port and read the stat pin again. in a high-z condition, the input port always matches the signal level on the output port. utc ub2012 sns bat v cc ts stat v ss cc comp out in host processor figure 9 interfacing the utc 2012 to a host processor low-power sleep mode the utc ub2012 enters the sleep mode if the v cc falls below the voltage at the bat input. this feature prevents draining the battery pack during the absence of v cc .
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 13 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) selecting an external pass-transistor the utc ub2012 is designed to work with both pnp transist or and p-channel mosfet. the device should be chosen to handle the required power dissipation, give n the circuit parameters, pcb layout and heat sink configuration. the following examples illust rate the design process for either device: pnp transistor: selection steps for a pnp bipolar transistor: example: v i = 4.5 v, i (reg) = 1 a, 4.2-v single-cell li-ion (utc ub2012c ). v i is the input voltage to the charger and i (reg) is the desired charge current (see figure 1). 1. determine the maximum power dissipation, p d , in the transistor. the worst case power dissipation happens when the cell voltage, v (bat) , is at its lowest (typically 3 v at the beginning of current regulation phase) and v i is at its maximum. where v cs is the voltage drop across the current sense resistor. p d = (v i -v (cs) -v (bat) )i (reg) (7) p d = (4.5-0.1-3)1a p d = 1.4w 2. determine the package size needed in order to ke ep the junction temperature below the manufacturer?s recommended value, t jmax . calculate the total theta, (c/w), needed. ja = d a(max) max(j) p ) t - (t (8) ja = 4 . 1 ) 40 - 150 ( ja = 78c/w now choose a device package with a theta at least 10% be low this value to account for additional thetas other than the device. a sot223 package, for inst ance, has typically a theta of 60c/w. 3. select a collector-emitter voltage, v (ce) , rating greater than the maximum input voltage. a 15-v device will be adequate in this example. 4. select a device that has at least 50% higher drain current i c rating than the desired charge current i (reg) . 5. using the following equation calculate the minimum beta ( or h fe ) needed: min =i cmax / i b (9) min =1 / 0.035 min =28 where i max(c)) is the maximum collector current (in this case same as i (reg) ), and i b is the base current (chosen to be 35 ma in this example). now choose a pnp transistor that is rated for v (ce) 15 v, ja 78c /w, i c 1.5 a, min 28 and that is in a sot223 package.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 14 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) selecting an external pass-transistor (cont.) p-channel mosfet: selection steps for a p-channel mosfet: example: v i = 5.5 v, i (reg) = 500ma, 4.2-v single-cell li-ion (utc ub2012 c). v i is the input voltage to the charger and i (reg) is the desired charge current (see figure 4). 1. determine the maximum power dissipation, p d , in the transistor. the worst case power dissipation happens when the cell voltage, v (bat) , is at its lowest (typically 3 v at the beginning of current regulation phase) and v i is at its maximum. where v d is the forward voltage drop across the re verse-blocking diode (if one is used), and v cs is the voltage drop across the current sense resistor. p d = (v i -v d -v (cs) -v (bat) )i (reg) (10) p d = (5.5-0.4-0.1-3)0.5a p d = 1w 2. determine the package size needed in order to ke ep the junction temperature below the manufacturer?s recommended value, t jmax . calculate the total theta, (c/w), needed. ja = d a(max) max(j) p ) t - (t (11) ja = 1 ) 40 - 150 ( ja = 110c/w now choose a device package with a theta at least 10% below this value to account for additional thetas other than the device. a sop-8 package, for inst ance, has typically a theta of 70c/w. 3. select a drain-source voltage, v (ds) , rating greater than the maximum input voltage. a 12 v device will be adequate in this example. 4. select a device that has at least 50% higher drain current (i d ) rating than the desired charge current i (reg) . 5. verify that the available drive is large enough to supply the desired charge current. v (gs) = (v d +v (cs) +v ol(cc) )-v i (12) v (gs) = ( 0.4+0.1+1.5)-5.5 v (gs) = -3.5 where v (gs) is the gate-to-source voltage, v d is the forward voltage drop across the reverse-blocking diode (if one is used), and v cs is the voltage drop across the current sense resistor, and v ol(cc) is the cc pin output low voltage specification for the utc ub2012 . select a mosfet with ga te threshold voltage, v (gsth) , rating less than the calculated v (gs) . now choose a p-channel mosfet transistor that is rated for v ds -15 v, ja 110c /w, i d 1 a, v (gsth) -3.5 v and in a sop package.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 15 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) selecting input capacitor in most applications, a high-frequency de coupling capacitor is required. a 0.1 f ceramic, placed in proximity to vcc and vss pins, works well. the utc ub2012 works with both regulated and unregulated external dc supplies. if a non-regulated supply is chosen, the supply unit should ha ve enough capacitance to hold up the supply voltage to the minimum required input voltage at maximum load, otherwise more capacitance must be added to the input of the charger. selecting output capacitor for loop stability, the utc ub2012 does not require any output capacitor. however, when a battery is not present, the user can add out put capacitance in order to control the out put voltage. the charger quickly charges the output capacitor to the regulation volt age, but the output voltage decays slowly , because of the low leakage current on the bat pin, down to the recharge threshold. addition of a 0.1 f ceramic capacitor, for instance, results in a 100 mv (pp) ripple waveform, with an appr oximate frequency of 25hz. higher capacit or values can be used if a lower frequency is desired. automatic charge-rate compensation in order to compensate safely for internal impedance of the battery pack, the utc ub2012 uses the automatic charge-rate compensation technique to reduce charging time. the automatic charge-r ate compensation feature is disabled by connecting the comp pin to vcc in current-sensing configuration. figure 12 outlines the main components of a single-cell li-ion battery pack. the li-ion battery pack consists of a cell, protection circuit, fuse, current sense-resistors, connector, and some wiring. there are some resistances in each of these components. total impedanc e of the battery pack is equal to t he sum of the minimum resistances of all battery-pack components. using the minimum resist ance values reduces the odds for overcompensating. overcompensating may activate the sa fety circuit of the battery pack. bat+ terminal fuse bat- wire terminal discharge charge wire wire cell wire protection controller figure 10 typical components of a single-cell li-lon pack compensation is achieved through input pin comp (f igure 13). a portion of the current-sense voltage, presented through this pin, is scaled by a factor of g (comp) and summed with the regulation threshold, v o(reg) . this process increases the output voltage to compensate for t he battery pack?s internal impedance and for undesired voltage drops in the circuit.
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 16 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) automatic charge-rate comp ensation setup requires the following information: * total impedance of battery pack (z (pack) ) * maximum charging current (i (reg) ) the voltage drop across the internal impedance of battery pack, v (z) , can then be calculated using the following equation: ) reg ( ) pack ( ) z ( i z = v (13) the required compensation is then calc ulated using the following equations: ) comp ( ) z ( ) comp ( g v = v (14) ) v g ( + v = v ) comp ( ) comp ( ) reg ( o ) pack ( where v (comp) is the voltage on comp pin. this voltage is referenced to vcc in current sensing configuration. v (pack) is the voltage across the battery pack. the values of r (comp1) and r (comp2) can be calculated using the following equation: 2 comp 1 comp 2 comp ) sns ( ) comp ( r + r r = v v (15) utc ub2012 sns bat v cc ts stat v ss cc comp dc+ dc- r sns r comp2 r comp1 bat+ figure 11. automatic charge- rate compensation circuits
ub2012 preliminary linear integrated circuit unisonic technologies co., ltd 17 of 17 www.unisonic.com.tw qw-r121-018 .b ? application information(cont.) the following example illustrates these calculations: assume z (pack) = 100 m ? , i (reg) = 500 ma, current sensing utc ub2012b ) reg ( ) pack ( ) z ( i z = v (16) v (z) =0.10.5 v (z) =50mv ) comp ( ) z ( ) comp ( g v = v (17) v (comp) =0.05/2.2 v (comp) =22.7mv let r comp2 = 10 k ? ) comp ( ) comp ( ) sns ( 2 comp 1 comp v ) v v ( r = r - (18) mv 7 . 22 ) mv 7 . 22 - mv 105 ( k 10 = r 1 comp 36.25k ? r comp1 = use the closest standard value (36.0 k ? ) for r comp1 utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.

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