unisonic technologies co., ltd us3702 preliminary linear integrated circuit www.unisonic.com.tw 1 of 9 copyright ? 2015 unisonic technologies co., ltd qw-r119-022.c high performance current mode power switch with zero current detection ? description the utc us3702 is an integrated pwm controller and sensefet specifically designed for switching operation with minimal external components. the utc us3702 is designed to provide several special enhancements to satisfy the needs, for example, power-saving mode for low standby power (<0.3w), frequency hopping , constant output power limiting , slope compensation ,over current pr otection (ocp), over voltage protection (ovp), over load pr otection (olp), under voltage lock out (uvlo), short circuit protection (scp) , over temperature protection (otp) etc. ic will be shutdown or can auto-restart in situations. ? feature * internal high voltage sensefet(700v) * frequency hopping for improved emi performance. * lower than 0.3w standby power design * linearly decreasing frequency to 26khz during light load * internal soft start * internal slope compensation * constant power limiting for universal ac input range * gate output maximum voltage clamp(15v) * over temperature protection * overload protection * over voltage protection * leading edge blanking * cycle-by-cycle current limiting * under voltage lock out * short circuit protection dip-8 ? ordering information ordering number package packing lead free halogen free us3702l-d08-t US3702G-D08-T dip-8 tube (1) t: tube (2) d08: dip-8 (3) l: lead free, g: halogen free and lead free us3702l -d08 -t (1)packing type (2)package type (3)green package
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 2 of 9 www.unisonic.com.tw qw-r119-022.c ? marking ? pin configuration 1 drain sgnd drain pgnd drain v cc nc 2 3 4 5 6 7 8 fb ? pin description pin no. pin name description 1 sgnd ground 2 pgnd mosfet ground 3 v cc supply voltage 4 fb feedback 5 nc 6 drain power mosfet drain 7 drain power mosfet drain 8 drain power mosfet drain
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 3 of 9 www.unisonic.com.tw qw-r119-022.c ? block diagram notes: olp (over load protection) ovp (over voltage protection) otp (over temperature protection) ocp (over current protection) uvlo (under voltage latch-out) leb (led edge blanking) ? absolute maximum rating (t a =25c, unless otherwise specified) parameter symbol ratings unit supply voltage v cc 30 v input voltage to fb pin v fb -0.3~6.5 v junction temperature t j +150 c operating temperature t opr -40~+125 c storage temperature t stg -50~+150 c note: 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. ? operating range parameter symbol ratings unit supply voltage v cc 7~23 v ? electrical characteristics (t a 25c, v cc =15v, unless otherwise specified) parameter symbol test conditions min typ max unit supply section start up current i st v cc = v thd ( on ) -1v 5 15 a supply current with switch i op v fb =4v gate without c load 2 3 ma under-voltage lockout section start threshold voltage v thd ( on ) 12 13.5 14 v min. operating voltage v cc ( min ) 7 8 9 v control section
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 4 of 9 www.unisonic.com.tw qw-r119-022.c feedback source current i fb v fb =0 2 ma v fb open level v fbmax 5.0 v burst-mode out fb voltage v fb ( out ) v cs =0 1.2 v reduce-frequency end fb voltage v fb ( end ) v cs =0 2.4 v burst-mode enter fb voltage v fb ( in ) v cs =0 1.0 v switching frequency normal initial f (sw) v fb =4v 69 75 81 khz power-saving before enter burst mode 20 khz duty cycle d max v fb =4v v cs =0 70 75 80 % frequency hopping f j ( sw ) 3 4.5 6 % frequency variation vs v cc deviation f dv v cc =10~20v 5 % frequency variation vs temperature deviation f dt t=-25~105c 5 % soft-start time t softs 2 4 6 ms protection section ovp threshold v ovp v fb =4v 23 v olp threshold v fb ( olp ) v cs =0 4.7 v delay time of olp t d-olp 35 65 95 ms otp threshold t ( thr ) 130 145 c current limiting section peak current limitation i lim v fb =4.4v 1.06 1.2 1.34 a threshold voltage for valley i lim-l v fb =4.4v 1.14 a
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 5 of 9 www.unisonic.com.tw qw-r119-022.c ? electrical characteristics (cont.) parameter symbol test conditions min typ max unit power mos-transistor section drain-source breakdown voltage v dss v gs =0v, i d =250ma 700 v turn-on voltage between gate and source v th v ds =v gs , i d =250ma 2 4 v drain-source diode continuous source current i s 2 a static drain-source on-state resistance r ds ( on ) v gs =10v, i d =2.25a 5 ? rise time t r v dd =300v, i d =4.0a r g =25 ? (note 1,2) 45 100 ns fall time t f 35 80 ns notes: 1. pulse test: pulse width 300 s, duty cycle 2% 2. essentially independent of operating temperature
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 6 of 9 www.unisonic.com.tw qw-r119-022.c ? functional description the internal reference voltages and bias circuit work at v cc > v thd (on) , and shutdown at v cc us3702 preliminary linear integrated circuit unisonic technologies co., ltd 7 of 9 www.unisonic.com.tw qw-r119-022.c ? functional description(cont.) (3) internal synchronized slope compensation built-in slope compensation circuit adds voltage ramp onto the current sense input voltage for pwm generation, this greatly improves the close loop st ability at ccm and prevents the sub-harmo nic oscillation and thus reduces the output ripple voltage. (4) frequency hopping for emi improvement the frequency hopping is implemented in the ic ; there are two oscillators built-in the ic. the first oscillator is to set the normal switching frequency; the switching frequency is modulated with a period signal generated by the 2nd oscillator. the relation between the first oscillator and th e 2nd oscillator as followed fig.5. so the tone energy is evenly spread out, the spread spectrum minimizes the conduction band emi and therefor e eases the system design in meeting stringent emi requirement. fig. 5 frequency hopping (5) constant output power limit when the primary current, across the prim ary wind of transfer, reaches the limit current, around 1.2a, the output gate drive will be turned off after a small propagation delay t d . this propagation delay will introduce an additional current proportional to t d v in /lp. since the propagation delay is nearly co nstant regardless of the input line voltage v in . higher input line voltage will result in a larger additional current and hence the output power limit is also higher than that under low input line voltage. to compensate for this output power limit variation across a wide ac input range, the limit current in pr imary winding is adjusted by adding a positive ra mp. this ramp signal rises from 1.14a to 1.2a, and then flattens out at 1.2a. a smaller limit current forces the output gate drive to terminate earlier. this reduces the total pwm turn-on time and makes the output po wer equal to that of low line input. this proprietary internal compensation ensures a constant output powe r limit for a wide ac input voltage range (90vac~264vac). (6) protection section the ic takes on more protection functions such as olp, ovp and otp etc. in case of those failure modes for continual blanking time, the driv er is shut down. at the same time, ic enters auto-restart, v cc power on and driver is reset after v cc power on again. olp after power on, ic will shutdown driver if over load state occurs for continual t d-olp . olp case as followed fig. 6. the test circuit as followed fig.8 ovp ovp will shutdown the switching of the power mosfet whenever v cc >v ovp . the ovp case as followed fig.7. the test circuit as followed fig.9.
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 8 of 9 www.unisonic.com.tw qw-r119-022.c ? functional description(cont.) fig.6 olp case fig.7 ovp case us3702 470u 2 1 3 4 7 8 6 5 33n ic3 v cc 15v v cc drain v ovp 2.5v 470u 33n v dd 15v 500 fig.8 olp test circuit fig.9 ovp test circuit otp otp will shut down driver when junction temperature t j > t (thr) for continual a blanking time. (7) driver output section the driver-stage drives the gate of the mosfet and is optimized to minimi ze emi and to provide high circuit efficiency. this is done by reducing the switch on slope when reaching the mosfet threshold. this is achieved by a slope control of the rising edg e at the driver?s output. the output driver is clamped by an internal 15v zener diode in order to protect power mosfet transistors against undesirable gate over voltage. (8) inside power switch mos transistor specific power mos transistor par ameter is as ?power mos transistor section? in electrical characteristics table.
us3702 preliminary linear integrated circuit unisonic technologies co., ltd 9 of 9 www.unisonic.com.tw qw-r119-022.c ? typical application circuit f1 line neut 8 9 10 1 2 3 4 l2 5v/2.4a gnd 1 4 7 ic1 6 7 4 3 1 2 l1 1 2 3 4 t1 ic3 ic2 bd1 t znr1 1 2 3 4 tr1 sgnd drain drain fb 8 3 v cc xc1 r1 r2 c1 r4 r3 d1 c2 yc1 r5 c8 c4 d2 c5 c10 c7 d3 c3 r6 c9 r12 r7 r8 r9 6 drain pgnd 2 c11 fig.10 utc us3702 typical application circuit table1. components reference descripti on for utc us3702 application circuit designator part type designator part type designator part type c1 33 f r1 2.2m ? d1 fr107 c2 202pf r2 2.2m ? d2 sb540 c3 22 f r3 100k ? d3 rs1d c4 470 f r4 1m ? ic1 us3702 c5 470 f r5 15 ? ic2 pc-817 c6 0.1 f r6 820 ? ic3 tl431 c7 102pf r7 1k ? yc1 222 c8 0.001 f r8 22k ? t1 ee25 c9 0.1 f r9 22k ? l1 uu10.5 c10 220 f r10 15~25m ? l2 2 h c11 1 f (optional) r11 68k ? f1 2a/250v r12 2k ? znr1 7d471k tr1 sck102r55a xc1 334/275v bd1 kbp205 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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