revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 1 features ? internal zener diode ? low cost emitter drive pwm solution ? 0.13w standby power ? current mode operation ? short circuit protection ? over-current protection ? over-temperature protection ? under-voltage lockout with auto-restart ? available in to-94 packages ? rohs compliant and 100% lead (pb)-free description the SE3901 is a green-mode pulse width modulation (pwm) controller. it is specifically designed for low power applications such as 5w-20w adaptors and off-line battery chargers. in these typical applications, the low standby power, space saving, and low cost are all required. SE3901 is a perfect solutions to meet these challenges. the typical standby power is only 0.13watt. in normal operation, the SE3901 switches on and off at a fixed switching freq uency of 60 khz. with a current limit capability of about 420ma, the SE3901 can directly drive the emitter of a high voltage npn transistor. when the output power falls below a given level, the ic enters skip cycle mode to reduce power consumption. the SE3901 also features under-voltage lockout , over-temperature protection, over-current and short circuit protections. the SE3901 is available in to-94 packages. pin configuration to-94 top view vcc gnd out zener application ? battery chargers ? universal off-li ne power supplies ? power adaptors ? led 3w-9w lighting solutions with se1051 pin description name pin# function vcc 1 the power supply of the ic, and is gener ally connected to opto-coupler's emitter gnd 2 supply ground out 3 the output pin, connected to the emitter of npn transistor. zener 4 the output pin, connected to internal zener
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 2 electrical characteristics (vcc=4v, t j =25 ,unless otherwise specified) parameter symbol conditions min typ max unit uvlo section start-up voltage v th (st) 5.00 5.25 5.5 v minimal operating voltage v opr (min) 3.4 3.65 3.9 v thermal protect thermal shutdown t sd 150 thermal hysteresis t hy 20 standby current section start-up current i st vcc=4v 0.22 0.4 ma operating current i cc(opr) 0.45 0.7 ma vcc zener voltage vz i cc =10ma 6 6.3 v dynamic impedance r vcc vcc=3.8 to 4.8v 9 k internal oscillator switching frequency f 50 60 75 khz drive output section out start-up voltage v st 8.5 11 v short circuit threashold voltage v sc 6 v maximum duty cycle d max v opr (min)+0.2 75 % minimum duty cycle vcc=vth(st)-0.2 3 % driver out on-resistance r out i out =0.06a 3 switch off current driver off, vout=10v 20 40 ua effective current limit i lim vcc= v opr +0.1v 420 ma out current coefficient g a -0.3 a/v absolute maximum rating symbol parameter maximum units vcc dc supply voltage -0.3 ~ 6 v out voltage at out -0.3~ 18 v ja thermal resistance junction to ambient (to92) 220 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
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 3 typical application 1 2 3 4 r1 10/ 1w bridge d1-d4 1n4007 r2 1.5m 1/4w r3 100k 1/2w d5 1n4007 q1 13003 c4 10uf r5 4.7 d7 1n4148 u2 out vcc gnd u1 SE3901 r6 200 c5 3.3n c6 10uf d8 sb240 c10 220uf/15v r9 100 r8 2k 220v 220v c12 2.2uf c8 222m 400v c9 z d6 1n4818 r4 400 c10 4.7uf/15v u3 se43 1 r11 10.7k r10 10k port port 5v/1a c12 104 fig.1 5v/1a mobile phone usb ch arger using SE3901(to94) and se431.
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 4 1 2 3 4 r1 10/ 1w bridge d1-d4 1n4007 r2 1.5m 1/4w r3 100k 1/2w d5 1n4007 q1 13003 c4 10uf r5 4.7 d7 1n4148 u2 out vcc gnd u1 SE3901 r6 200 c5 3.3n c6 10uf d8 sb240 c10 220uf/15v u3 se1051 r10 0.8k r11 100 r8 2k r12 22k r13 470k vcc vout ictrl c12 224 c13 104 vct rl vsense gnd r16 r14 1k r15 10k r17 89k 220v 220v 12v/700ma c12 2.2uf c8 222m 400v c9 0.34ohm z d6 1n4818 r4 400 c10 4.7uf/15v fig.2 12v/700ma lighting 9w led so lution using SE3901(to94) and se1051.
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 5 1 2 3 4 r1 10/ 1w bridge d1-d4 1n4007 r2 1.5m 1/4w r3 100k 1/2w d5 1n4007 q1 13003 c4 10uf r5 4.7 d7 1n4148 u2 out vcc gnd u1 SE3901 r6 200 c5 3.3n c6 10uf d8 sb240 c10 220uf/15v r10 0.8k r11 100 r8 2k r12 22k r13 470k vcc vout ictrl c12 224 c13 104 vct rl vsense gnd r16 r14 1k r15 10k r17 60k 220v 220v c12 2.2uf c8 222m 400v c9 0.05ohm z d6 1n4818 r4 400 c10 4.7uf/15v led-r led-g red gre e n r18 1k bat1 bat2 8.4v/2a fig.3 8.4v/1a 2 cell batteries char ger, using SE3901(to94) and se1052. note: se1052 integrates voltage reference, voltage setting and current setting and led drivers all in the same ic. when the charging is on-going, the red led is on and the green led is off. when the charging is completed, the green led is on and the red led is off. the charging current can be programmed by setting the r16 to the proper valu e. please refer to se1052 datasheet for details.
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 6 outline drawing to94
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? page 7 outline drawing sot143
revision 1/20/2009 preliminary and all contents are subject to change without prior notice. ? seaward electronics, inc., 2008. ? www.seawardinc.com ? 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 - 1/20/2009
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