revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 1 features ? constant voltage and constant current control ? low voltage operation ? precision internal voltage references ? low external component count ? current sink output stage ? easy compensation ? low ac mains voltage rejection ? rugged 1.5kv esd withstand capability. ? internal 2 led drivers ? available in sop8 and dip-8 package. ? rohs compliant and 100% lead (pb)-free description SE1052 is a highly integrated solution for smps applications requiring cv (constant voltage) and cc (constant current) modes. it also has built-in led drivers specifically designed for stand-alone battery charging applications. SE1052 integrates three voltage references, three operational amplifiers, and two current sensing circuits together in the same ic. the 1 st voltage reference, together with one operational amplifier, contro ls the output voltage. the 2 nd voltage reference, together with another operational amplifier, sens es and limits the amount of the current on the low side, hence the overall current at the output. the 3 rd voltage reference and operational amplifier senses when the charging current drops to 10% of the programmed value. during charging, SE1052 will turn on red led. when the charging is completed, SE1052 will turn on green led. the SE1052 is available in sop8 and dip8 package. pin configuration gre e n ou tp ut gnd vctrl vcc vsens e ic trl red 1 2 3 45 6 7 8 green ou tp ut gnd vctrl vcc vsense ic trl red 1 2 3 45 6 7 8 sop8 top view di p8 top v iew application ? adapters ? digital camera chargers. ? cellphone chargers. ? other battery chargers ordering information device package v out SE1052 sop8 and dip8 (lead-free) fixed output voltages 1.21v pin description name pin# type function green 1 driver turning on green led when the charging is completed. v out 2 current sink output output pin. sinking current only gnd 3 power supply ground line. 0v reference for all voltages v ctrl 4 analog input input pin of the voltage control loop v cc 5 power supply positive power supply line v sense 6 analog input input pin of the current control loop i ctrl 7 analog input input pin of the current control loop red 8 driver turning on red led when the charging is in progress.
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 2 absolute maximum rating symbol parameter maximum units v cc dc supply voltage 18 v v in input supply voltage -0.3~ v cc v ja thermal resistance junction to ambient 250 c/w t j operating junction temperature range 0 to 125 c t stg storage temperature range -40 to 150 c t lead lead temperature (soldering 10 sec) 260 c electrical characteristic v cc = 5.0v, t a = 25c, unless otherwise specified. symbol parameter conditions min typ max unit total current comsuption i cc total supply current - not taking the output sinking current into account isink=0 0.7 1.2 2.5 ma voltage control loop g mv transconduction gain (vctrl). sink current only 1 isink=0 to 10ma 2.4 ma/mv v ref voltage control loop reference 2 isink=0 1.198 1.21 1.222 v lr v linear regulation of voltage control loop reference vcc= 2.5v to 18v 0.6 8 mv i ibv input bias current (vctrl) 70 na v ol low output voltage at 10ma sinking current vctrl=vcc, ictrl=vsense=gnd, isink=10ma, g and r pins open 250 350 mv i os output short circuit current. output to vcc. sink current only vctrl=vout=vcc, ictrl=vsense=gnd, g and r pins open 15 24 35 ma current control loop g mi transconduction gain (ictrl). sink current only 3 isink=0 to 5ma 7.2 ma/mv v sense current control loop reference 4 isink=0 192 200 208 mv lr i linear regulation of current control loop reference vcc=2.5v to 18v 0.8 4 mv i ibi current out of pin ictrl at -200mv 20 ua v ol low output voltage at 10ma sinking current vsense=vcc, ictrl=vctrl=gnd, isink=10ma, g and r pins open 250 350 mv i os output short circuit current. output to vcc. sink current only vsense=vout=vcc, ictrl=vctrl=gnd, g and r pins open 15 24 35 ma
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 3 electrical characteristic v cc = 5.0v, t a = 25c, unless otherwise specified. symbol parameter conditions min typ max unit current monitor loop v th threshold voltage of turning red pin from low to high 20 mv h ys hysterisis of the comparator in current monitor loop 14 mv 1. if the voltage on v ctrl (the negative input of the amplifier) is higher than th e positive amplifier input (v ref =1.210v), and it is increased by 1m v, the sinking current at the out put out will be increased by 2.4ma. 2. the internal voltage reference is set at 1.210v. t he internal voltage reference is fixed by bandgap, and trimmed to 1% accuracy at room temperature. 3. when the positive input at i ctrl is lower than -200mv, and the voltage is decreased by 1mv, the sinking current at the output out will be increased by 2.9ma. 4. the internal current sense threshold is set to -200mv. the current control loop prec ision takes into account the cumulative effects of the internal voltage reference deviation as well as the input offset voltage of the trans-conduction operational amplifier.
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 4 typical application 1.210v ictrl vsense green red vctrl output vcc gnd 100mv 10mv rsense r2 r1 ri c2 ri c1 ci c1 c2 rvc1 cvc1 2.2nf 22 pf 2.2nf led_g led_r v out+ vout- to primary SE1052 rout rl ed 1k cs rs note 0 ohms of ric2 is recommended for led charging indication function.
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 5 application hints voltage control the voltage loop is controlled via a first transconductance operational amplifier, the resistor bridge r1, r2, and the optocoupler which is directly connected to the output. the relation between the values of r1 and r2 should be chosen as written in equation 1. r1 = r2 x vref / (vout - vref) eq1 where vout is the desired output voltage. to avoid the discharge of the load, the resistor bridge r1, r2 should be highly resistive. for this type of application, a total value of 100k (or more) would be appropriate for the resistors r1 and r2. as an example, with r2 = 100k , vout = 4.10v, vref = 1.210v, then r1 = 41.9k . note that if the low drop diode should be inserted between the load and the voltage regulation resistor bridge to avoid current flowing from the load through the resistor bridge, this drop should be taken into account in the above calculations by replacing vout by (vout + vdrop). current control the current loop is controlled via the second trans-conductance operational amplifier, the sense resistor rsense, and the optocoupler. the control equation is: rsense x i-limit = vsense eq2 rsense = vsense / i-limit eq3 where i-limit is the desired current limit, and vsense is the threshold voltage for the current control loop. as an example, with i-limit = 1a, vsense = -200mv, then rsense = 200m . note that the rsense resi stor should be selected with the consideration of the maximum power in full load operations (p-limit). p-limit = vsense x i-limit. eq4 as an example, with i-limit = 1a, and vsense =-200mv, p-limit = 200mw. consequently, for most adapter and battery charger applications, a quarter-watt resistor to make the current sensing function is sufficient. vsense threshold is achieved internally by a resistor bridge tied to the vref voltage reference. its middle point is tied to the positive input of the current control operational am plifier, and its foot is to be connected to lower potential point of the sense resistor as shown on the following figure. the resistors of this bridge are matched in layout to provide the best precision possible. the current sinking outputs of the two trans-conductance operational amplifiers are connected together. this makes an oring function which ensures that whenever the current or the voltage reaches too high values, the optocoupler is activated. the relation between the controlled current and the controlled output voltage can be described with a square characteristic as shown in the following v/i output-power graph. fig.2 output voltage versus output current compensation the voltage-control trans-conductance operational amplifier can be fully compensated. both of its output and negative input ar e directly accessible for external compensation components. an example of a suitable compensation network is shown in fig.1. it consists of a capacitor cvc1=2.2nf and a resistor rcv1=470k in series, connected in parallel with another capacitor cvc2=22pf. the current-control trans-conductance operational amplifier can also be fully compensated. both of its output and negative input ar e directly accessible for external compensation components. an example of a suitable compensation network is shown in fig.1. it consists of a capacitor cic1=2.2nf and a resistor ric1=22k in series. when the vcc voltage reaches 12v it could be interesting to limit the current coming through the output in the aim to reduce the dissipation of the device and increase the stability performances of the whole application. an example of a suitable rout value could be 330 in series with the opto-coupler in case vcc=12v. driving led SE1052 provides direct driving pins to red and green led?s for charging applications. during charging, SE1052 will turn on red led. when the charging is completed, SE1052 will turn on green led.
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 6 start up and short circuit conditions under start-up or short-circuit conditions the SE1052 does not have a high enough supply voltage. this is due to the fact that the chip has its power supply lin e in common with the power supply line of the charger system. consequently, the current limitation can only be ensured by the primary pwm module, which should be designed accordingly. if the primary current limitation is considered not to be precise enough for the app lication, then a sufficient supply for the SE1052 has to be ensured under any co ndition. it would then be necessary to add some circuitry to supply the chip with a separate power line. this can be achieved in numerous ways, including an additional winding on the transformer. the following schematic shows how to realize a lo w-cost power supply for the SE1052 (with no additional windings). please pay attention to the fact that in the particula r case presented here, this low-cost power supply can reach voltages as high as twice the voltage of the regu lated line. since the absolute maximum rating of the SE1052 supply voltage is 18v, this low-cost auxiliary pow er supply can only be used in applications where the regulated line voltage does not exceed 9v. 1.210 v ictrl vsense green red vctrl output vcc gnd 100mv 10mv rsense r2 r1 ri c2 ri c1 ci c1 c2 rvc1 cvc1 2.2nf 22 p f 2.2nf led_g led_r vout+ vout- to primary SE1052 rout rs rl ed 1k cs note 0 ohms of ric2 is recommended for led charging indication function.
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 7 outline drawing dip-8 outline drawing sop-8 1 2 3 4 5 6 7 8 h e d a1 a b b1 c min max min max a 0.0532 0.0688 1.35 1.75 a1 0.0040 0.0098 0.10 0.25 b 0.0130 0.0200 0.33 0.51 b1 c 0.0075 0.0098 0.19 0.25 d 0.1890 0.1968 4.80 5.00 h 0.2284 0.2440 5.80 6.20 e 0.1497 0.1574 3.80 4.00 dimensions 0.050 bsc 1.27 bsc dim n inches mm
revision 5/7/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2006. ? www.seawardinc.com.cn ? page 8 customer support seaward electronics incorporated ? china section b, 2nd floor, shangdi scientific office complex, #22 xinxi road haidian district, beijing 100085, china tel: 86-10-8289-5700/01/05 fax: 86-10-8289-5706 seaward electronics corporation ? taiwan 2f, #181, sec. 3, minquan east rd, ta i p e i , ta i w a n r . o . c tel: 886-2-2712-0307 fax: 886-2-2712-0191 seaward electronics incorporated ? north america 1512 centre pointe dr. milpitas, ca95035, usa tel: 1-408-821-6600 last updated - 5/7/2009
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