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an-064e rev.1.1 april 2011 1 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ fuji switching power supply control ic green mode quasi-resonant ic FA5640/41/42 application note april 2011 fuji electric co., ltd.
an-064e rev.1.1 april 2011 2 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 1. the contents of this note (product specification, characteristics, data, materials, and structure etc.) were prepared in april 2011. the contents will subject to change without notice due to product specification change or some other reasons. in case of using the products stated in this document, the latest product specification shall be provided and the data shall be checked. 2. the application examples in this note show the typical examples of using fuji products and this note shall neither assure to enforce the industrial property including some other rights nor grant the license. 3. fuji electric co.,ltd. is always enhancing the product quality and reliability. however, semiconductor products may get out of order in a certain probability. measures for ensuring safety, such as redundant design, spreading fire protection design, malfunction protection design shall be taken, so that fuji electric semiconductor product may not cause physical injury, property damage by fire and social damage as a result. 4. products described in this note are manufactured and intended to be used in the following electronic devices and electric devices in which ordinary reliability is required: - computer - oa equipment - communication equipment (pin) - measuring equipment - machine tool - audio visual equipment - home appliance - personal equipment - industrial robot etc. 5. customers who are going to use our products in the following high reliable equipments shall contact us surely and obtain our consent in advance. in case when our products are used in the following equipment, suitable measures for keeping safety such as a back-up-system for malfunction of the equipment shall be taken even if fuji electric semiconductor products break down: - transportation equipment (in-vehicle, in-ship etc.) - communication equipment for trunk line - traffic signal equipment - gas leak detector and gas shutoff equipment - disaster prevention/security equipment - various equipment for the safety. 6. products described in this note shall not be used in the following equipments that require extremely high reliability: - space equipment - aircraft equipment - atomic energy control equipment - undersea communication equipment - medical equipment. 7. when reprinting or copying all or a part of this note, our company?s acceptance in writing shall be obtained. 8. if obscure parts are found in the contents of this note, contact fuji electric co.,ltd. or a sales agent before using our products. fuji electric co.,ltd. and its sales agents shall not be liable for any damage that is caused by a customer who does not follow the instructions in this cautionary statement. caution
an-064e rev.1.1 april 2011 3 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ contents 1. overview ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 4 2. features ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 4 3. outline drawings ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 4 4. block diagram ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 5-6 5. functional description of pins ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 7 6. rating and characteristics ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 7-12 7. characteristic curve ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 13-17 8. basic operation ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 18 9. description of the function ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 19-24 10. how to use pin and advice designing ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 25-33 11. precautions for pattern design ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 34 12. example of application circuit ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 35 caution) ? the contents of this note will subject to change without notice due to improvement. ? the application examples or the components constants in this note are shown to help your design, and variation of components and service conditions are not taken into account. in using these components, a design with due consideration for these conditions shall be conducted.
an-064e rev.1.1 april 2011 4 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 1. overview FA5640 series are a quasi-resonant type switching power supply control ic with excellent stand-by characteristics. though it is a small package with 8 pins, it has a lot of functions and enables to decrease external parts. therefore it is possible to realize a small size and a high cost-performance power supply. 2. features ? a quasi-resonant type switching power supply ? a power supply with excellent standby characteristics ? low power consumption achieved by integrated startup circuit ? low current consumption, during operation: 0.85 ma ? control of number of bottom skips by on-off width detection ? burst operation function under light load ? built-in drive circuit directly connectable to a power mosfet, output current: 0.5 a (sink)/0.25 a (source) ? built-in overload protection function ? built-in latch protection function based on overvoltage detection on the secondary side ? maximum input threshold voltage of is pin and threshold voltage of stopping on-pulse are compensated by detecting high-line voltage. ? built-in under voltage lock out function, on threshold voltage: 14 v and 10 v ? package: sop-8 function list by types (lineup is under review.) type overload protection on threshold voltage operation compensation minimum switching frequency delay time of restart FA5640 auto recovery 14v yes no 25us fa5641 auto recovery 14v yes 25khz 7.6us fa5642 auto recovery 10v no no 25us * see 10. (9) ?other advice on designing? for details of the lineup without the minimum oscillating frequency function. 3. outline drawings 0 . 6 5 0 . 2 5 0 1 0 3 . 9 0 . 2 1 . 8 m a x 1.27 5.0 0.25 1 pin mark 0 . 2 0 . 1 0.4 0.1 0 . 2 6 . 0 0 . 3 sop-8
an-064e rev.1.1 april 2011 5 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 4. block diagram FA5640 fa5641 bottom detection s r1 q startup current uvlo vh vcc 4.8v reg. internal supply driver out startup management 11v/9v 3.5/3.3v overload 14v/8v enb gnd fb is zcd timer 200ms 1600ms disable soft start (1ms) current comparator 4.8v 4.8v 1/6 10 a latch timer 60 s zcd ovp1 off timer (4.5 s) latch protection 6v ovp detection zcd enb olp protection reset off timer (2 s) r2 input voltage detection mode select signal vinh 24k resistance ratio mp1 on/off 91.3%/100% 84.1%/100% 30k 7.5v 1 shot (290ns) enb set bottom skip control max. ton (24 s) reset pulse width detection 0.5v vinh 0.45v vthis restart timer 25 s 0.45v vinh 0.35v vthfb0 0.55v standby standby detection + - vinh 0.15v vinh 0.10v vthis at standby mp1
an-064e rev.1.1 april 2011 6 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ fa5642 bottom detection s r1 q startup current uvlo vh vcc 4.8v reg. internal supply driver out startup management 11v/9v 3.5/3.3v overload 10v/8v enb gnd fb is zcd timer 200ms 1600ms disable soft start (1ms) current comparator 4.8v 4.8v 1/6 10 a latch timer 60 s zcd ovp1 off timer (4.5 s) latch protection 6v ovp detection zcd enb olp protection reset off timer (2 s) r2 24k resistance ratio mp1 on/off 91.3%/100% 30k 7.5v 1 shot (290ns) enb set bottom skip control max. ton (24 s) reset pulse width detection 0.5v vthis restart timer 25 s 0.45v vthfb0 0.55v standby standby detection + - 0.15v vthis at standby mp1
an-064e rev.1.1 april 2011 7 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 5. functional description of pins pin number pin name pin function 1 zcd zero current detection, ovp detection 2 fb feedback input, olp detection, burst operation control 3 is current sense input, over-current limiter, standby signal detection 4 gnd ground 5 out output 6 vcc power supply, uvlo, vh pin current control 7 (n.c.) no connection 8 vh high voltage input 6. rating and characteristics * ?+? shows sink and ??? shows source in current prescription. (1) absolute maximum ratings item symbol rating unit supply voltage vcc 28 v ioh -0.25 a peak current at out pin (note 1) iol +0.5 a the voltage at out pin vout -0.3 to vcc+0.3 v input voltage at fb and is pin vfb, vis -0.3 to 5.0 v the current at fb and is pin ifb, iis -0.3 to +0.3 ma isozcd -2.0 ma the current at zcd pin isizcd +3.0 ma the voltage at zcd pin vzcd -2 to +8 v input voltage at vh pin vvh -0.3 to 500 v power dissipation ta=25 pd 400 mw operating junction temperature tj -40 to +125 storage temperature tstg -40 to +150 note 1) please consider power supply voltage and load current well and use this ic within maximum power dissipation, operating junction temperature and recommended ambient temperature in operation. the ic may cross over maximum power dissipation at normal operating condition by power supply voltage or load current within peak current absolute maximum rating. * allowable loss reduction characteristics package thermal resistor j-a= 250 w 400 S p ? m a x i m u m d i s s i p a t i o n p d [ m w ] 25 85 125 ambiance temperature ta [ ] -40 0
an-064e rev.1.1 april 2011 8 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (2) recommended operating conditions item symbol min. typ. max. unit supply voltage vcc 11 15 26 v input voltage at vh pin vvh 50 450 v capacitance at vcc pin cvcc 10 47 220 uf turn-off resonant period trs 2 4 us ambient temperature in operation ta -40 85 (3) dc electric characteristics (unless otherwise specified : vcc=15v, vh=141v, zcd=0v, fb=3v, is=open, tj=25 ) current sense part (is pin) item symbol conditions min. typ. max. unit input bias current iis vis=0v -15 -10 -5 ua vthis1 vfb=3.2v, vvh=141v 0.47 0.5 0.53 v maximum threshold voltage vthis2 FA5640,fa5641 vfb=3.2v, vvh=324v 0.42 0.45 0.48 v v o l t a g e g a i n a v i s v f b / v i s 5 . 4 6 . 0 6 . 6 v / v minimum on pulse width tonmin vfb=3.2v,vis=1.5v 205 290 375 ns delay to output tpdis is input: 0v to 1.5v (pulse signal) 30 70 150 ns feedback part (fb pin) item symbol conditions min. typ. max. unit vthfb01 duty=0% vvh=141v 405 450 495 mv input threshold voltage of stopping on-pulse vthfb02 FA5640,fa5641 duty=0% vvh=324v 315 350 385 mv rfb11 vfb=1v to 2v vvh=141v 1 4 . 2 1 8 . 9 2 3 . 6 k rfb12 vfb=1v to 2v vvh=324v 1 3 . 0 1 7 . 4 2 1 . 7 k rfb21 vfb=0v to 0.3v vvh=141v 1 5 . 5 2 0 . 7 2 5 . 9 k fb pin input resistance rfb22 vfb=0v to 0.3v vvh=324v 1 5 . 5 2 0 . 7 2 5 . 9 k fb pin source current ifb0 vfb=0v -260 -200 -160 ua S rfb1 S rfb1=rfb11/rfb21 vvh=141v 89.3 91.3 93.3 % fb pin input resistance ratio S rfb2 FA5640,fa5641 S rfb2=rfb12/rfb22 vvh=324v 82.1 84.1 86.1 %
an-064e rev.1.1 april 2011 9 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ zero current detection part (zcd pin) item symbol conditions min. typ. max. unit vthzcd1 vzcd decreasing 40 60 80 mv input threshold voltage vthzcd2 vzcd increasing 100 150 220 mv hysteresis vhyzcd vthzcd2-vthzcd1 30 90 150 mv minimum detectable pulse width tzcdmin zcd input pulse vpulse=1v to 0v f=100khz 300 ns vih izcd=+3ma high state 6.5 7.5 9.5 v input clamp voltage vil izcd=-2ma low state -1.0 -0.8 -0.4 v zcd pin internal e s i s t a n c e r z c d v z c d = 1 v t o 5 v 2 2 . 5 3 0 3 7 . 5 k zcd pin propagation delay time tzcd zcd pulse:1v to 0v, out: turn-on 50 150 300 ns tb12 changed 1st bottom to 2nd bottom 8.1 9.0 9.9 us tb21 changed 2nd bottom to 1st bottom 12.6 14.0 15.4 us tb23 changed 2nd bottom to 3rd bottom 7.2 8.0 8.8 us tb32 changed 3rd bottom to 2nd bottom 10.5 11.67 12.84 us tb34 changed 3rd bottom to 4th bottom 6.3 7.0 7.7 us the on/off pulse width of changed number of bottom at turn-on tb43 changed 4th bottom to 3rd bottom 9.0 10.0 11.0 us FA5640,fa5642 out=low, vzcd=0v 20 25 30 us timeout after last zcd trigger trestart fa5641 out=low, vzcd=0v 6.7 7.6 8.5 us over-voltage protection part (zcd pin) item symbol conditions min. typ. max. unit over-voltage threshold voltage vovp vzcd is increased, and timer latch function is operated 5.7 6.0 6.3 v over-voltage detection timing tlat1 delay from turn-off 3.5 4.5 5.5 us delay time to latch-off tla 2 delay from upper the vovp voltage 40 60 80 us overload protection part (fb pin) item symbol conditions min. typ. max. unit volp1 vfb increasing 3.3 3.5 3.8 v olp threshold voltage volp2 vfb decreasing 3.0 3.3 3.6 v hysteresis hysolp volp1-volp2 0.1 0.2 0.3 v fault time duration tolp delay from vfb>volp1 140 200 260 ms auto recovery mode latch-off time duration toff the off time only by internal signal 980 1400 1820 ms
an-064e rev.1.1 april 2011 10 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ soft start part item symbol conditions min. typ. max. unit soft-start time tsoft at start-up only 0.7 1.0 1.3 ms standby-mode function (is pin) item symbol conditions min. typ. max. unit stand-by detection threshold voltage at is pin visstb read timing is turn-off after tstb. 0.5 0.55 0.6 v stand-by detection timing tstb delay from turn-off 1.5 2.0 2.5 us vthiss 1 vfb=3.2v vvh=141v 0.12 0.15 0.18 v maximum threshold voltage at stand-by vthiss 2 FA5640,fa5641 vfb=3.2v vvh=324v 0.07 0.10 0.13 v other protection part item symbol conditions min. typ. max. unit maximum on pulse width tonmax vis=0v, vis=2v vzcd=0v 20 24 28 us minimum switching frequency fmin fa5641 vis=0v,vfb=3.2v 20.8 25 30.3 khz drive output part (out pin) item symbol condition min. typ. max. unit out low voltage vol iol=100ma vcc=15v 0.5 1.0 2.0 v out high voltage voh ioh=-100ma, vcc=15v 12 13.2 14.5 v rise time tr vcc=15v, cl=1nf tj=25 20 40 80 ns fall time tf vcc=15v, cl=1nf tj=25 12.5 25 60 ns
an-064e rev.1.1 april 2011 11 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ high voltage input part (vh pin) item symbol condition min. typ. max. unit ivhrun vvh=400v, vcc > vstoff 10 30 60 ua ivh1 vvh=100v, vcc=6.5v 4.0 8.0 10.5 ma supply current of vh pin ivh0 vvh=100v, vcc=0v 0.49 0.7 1.4 ma ipre1 vcc=8v, vvh=100v -10 -7.4 -3.7 ma charge current for vcc pin ipre2 vcc=13v, vvh=100v at uvlo mode -9 -5.7 -3 ma vhdch FA5640,fa5641 vcc>vstoff vh pin input voltage is increasing by dc voltage. 200 226 250 v the threshold voltage to change input voltage mode setting at dc input vhdcl FA5640,fa5641 vcc>vstoff vh pin input voltage is decreasing by dc voltage. 190 212 235 v hysteresis voltage width at dc input only vhdchys FA5640,fa5641 vh: dc voltage input vhdch-vhdcl 8 14 18 v the threshold voltage to change input voltage mode setting at ac input (ac rms conversion voltage) vhac FA5640,fa5641 vcc>vstoff vh pin input voltage is half-wave rectified ac waveform. 141 160 177 vrms delay time of changing input voltage mode setting tpdvh FA5640,fa5641 vcc>vstoff (vcc charge off) 11 30 70 ms low voltage malfunction protection circuit (uvlo) part (vcc pin) item symbol condition min. typ. max. unit FA5640,fa5641 vcc increasing 12.5 14 15.5 v start-up threshold voltage vccon fa5642 vcc increasing 9 10 11 v shutdown threshold voltage vccoff vcc decreasing 7 8 9 v hysteresis (uvlo) vhys1 FA5640,fa5641 vccon-vccoff 5 6 7 v istart-up off voltage fa5642 vccon-vccoff 1.5 2 2.5 v istart-up restart voltage vstoff vcc increasing 9.5 11 12.5 v hysteresis width at istart-up vstrst vcc decreasing 8 9 10 v
an-064e rev.1.1 april 2011 12 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ current consumption (vcc pin) item symbol condition min. typ. max. unit iccop1 vfb=2v, is=open vzcd=0v out= no load 0.7 0.85 1.5 ma operating-state supply current iccop2 duty cycle=0%, vfb=0v, is=open vzcd=0v 0.6 0.8 1.1 ma latch mode supply current icclat fb=open vcc=11v at latch-mode 100 200 350 ua *1 : regarding to these items, guaranteed by design. the column showing ?-? has no specified value.
an-064e rev.1.1 april 2011 13 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 7. characteristic curve ? unless otherwise specified : tj=25 ?? , vcc=15v ? ?+? shows sink and ??? shows source in current prescription. ? data listed here shows the typical characteristics of an ic and does not guarantee the characteristics. is pin maximum threshold voltage (vthis1) vs. junction temperature (tj) 0.47 0.48 0.49 0.5 0.51 0.52 0.53 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h i s 1 [ v ] is pin maximum threshold voltage (vthis2) vs. junction temperature (tj) 0.42 0.43 0.44 0.45 0.46 0.47 0.48 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h i s 2 [ v ] fb pin input threshold voltage switching off (vthfb01) vs. junction temperature(tj) 400 410 420 430 440 450 460 470 480 490 500 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h f b 0 1 [ m v ] fb pin input threshold voltage switching off (vthfb02) vs. junction temperature (tj) 315 325 335 345 355 365 375 385 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h f b 0 2 [ m v ] is pin maximum threshold voltage (vthis1) vs. fb pin voltage (vfb) 0 0.1 0.2 0.3 0.4 0.5 0.6 0 1 2 3 4 vfb [v] v t h i s 1 [ v ]
an-064e rev.1.1 april 2011 14 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ zcd pin input threshold voltage (vthzcd2) vs. junction temperature (tj) 100 120 140 160 180 200 220 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h z c d 2 [ m v ] zcd pin internal resistance (rzcd) vs. junction temperature (tj) 22.5 25 27.5 30 32.5 35 37.5 -50 -25 0 25 50 75 100 125 150 tj [ ] r z c d [ k ] zcd pin ovp threshold voltage (vovp) vs. junction temperature (tj) 5.7 5.8 5.9 6 6.1 6.2 6.3 -50 -25 0 25 50 75 100 125 150 tj [ ] v o v p [ v ] delay time to olp (tolp) vs. junction temperature (tj) 140 160 180 200 220 240 260 -50 -25 0 25 50 75 100 125 150 tj [ ] t o l p [ m s ] zcd pin input threshold voltage (vthzcd1) vs. junction temperature (tj) 20 30 40 50 60 70 80 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h z c d 1 [ m v ] olp off time (toff) vs. junction temperature (tj) 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 -50 -25 0 25 50 75 100 125 150 tj [ ] t o f f [ m s ]
an-064e rev.1.1 april 2011 15 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ input current of vh pin (ivhrun) vs. junction temperature (tj) 10 15 20 25 30 35 40 45 50 55 60 -50 -25 0 25 50 75 100 125 150 tj [ ] i v h r u n [ u a ] input current of vh pin (ivh1) vs. junction temperature (tj) 4 5 6 7 8 9 10 11 -50 -25 0 25 50 75 100 125 150 tj [ ] i v h 1 [ m a ] input current of vh pin (ivh0) vs. junction temperature (tj) 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 -50 -25 0 25 50 75 100 125 150 tj [ ] i v h 0 [ m a ] input current of vh pin (ivh) vh pin voltage (vvh) 0 1 2 3 4 5 6 7 8 9 10 0 100 200 300 400 500 vvh [v] i v h [ m a ] is pin maximum threshold voltage at standby (vthisst1) vs. junction temperature (tj) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h i s s t 1 [ v ] is pin maximum threshold voltage at standby (vthisst2) vs. junction temperature (tj) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 -50 -25 0 25 50 75 100 125 150 tj [ ] v t h i s s t 2 [ v ]
an-064e rev.1.1 april 2011 16 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ charge current for vcc pin (ipre1) vs. junction temperature (tj) -10 -9 -8 -7 -6 -5 -4 -3 -50 -25 0 25 50 75 100 125 150 tj [ ] i p r e 1 [ m a ] shutdown threshold voltage (vccoff) vs. junction temperature (tj) 7 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9 -50 -25 0 25 50 75 100 125 150 tj [ ] v c c o f f [ v ] operating-state supply current (iccop1) vs. vcc pin voltage (vcc) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 5 10 15 20 25 30 vcc [v] i c c o p 1 [ m a ] startup threshold voltage (vccon) vs. junction temperature (tj) 12.5 13 13.5 14 14.5 15 15.5 -50 -25 0 25 50 75 100 125 150 tj [ ] v c c o n [ v ] startup device on voltage (vstrst) vs. junction temperature (tj) 8 8.2 8.4 8.6 8.8 9 9.2 9.4 9.6 9.8 10 -50 -25 0 25 50 75 100 125 150 tj [ ] v s t r s t [ v ] startup device off voltage (vstoff) vs. junction temperature (tj) 9.5 10 10.5 11 11.5 12 12.5 -50 -25 0 25 50 75 100 125 150 tj [ ] v s t o f f [ v ]
an-064e rev.1.1 april 2011 17 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ latch mode supply current (icclat) vs. junction temperature (tj) 100 150 200 250 300 350 -50 -25 0 25 50 75 100 125 150 tj [ ] i c c l a t [ u a ] operating-state supply current (iccop1) vs. junction temperature (tj) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 -50 -25 0 25 50 75 100 125 150 tj [ ] i c c o p 1 [ m a ]
an-064e rev.1.1 april 2011 18 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 8. basic operation (the values in the following description are typical values unless otherwise specified.) the basic operation of the power supply using ic is not switching operation with fixed frequency using an oscillator but switching with self-excited oscillation. this is shown in fig.1 schematic circuit diagram and fig.2 waveform in the basic operation. t1 to t2 q1 turns on and then q1 drain current id (current of primary windings of t1) begins to rise from zero. q1 current is converted into the voltage by rs and is input into is pin. t2 when the current of q1 get to the reference voltage of the current comparator that is fixed by the voltage of fb pin, a reset signal is input into rs flip-flop and q1 turns off. t2 to t3 when q1 turns off, then the windings voltage of the transformer turns over and the current i f is provided from the transformer into the secondary side through d1. t3 to t4 when the current from the transformer into the secondary side stops and the current of d1 gets to zero, the voltage of q1 turns down rapidly due to the resonance of the transformer inductance and the capacitor cd. at the same time the transformer auxiliary windings voltage vsub also drops rapidly. zcd pin receives this auxiliary windings voltage but then it has a little delay time because of cr circuit composed with r zcd and c zcd on the way. t4 if zcd pin voltage turns down lower than the threshold voltage 50mv of bottom detection, a set signal is input into r-s flip-flop and q1 turns on again. if the delay time of cr circuit placed between the auxiliary windings and zcd pin is adjusted properly, q1 voltage can be turned on at the bottom. this operation makes the switching loss of turn on to the minimum. (return to t1) subsequently repeat from t1 to t4 and continue switching. out (q1 gate) q1 vds q1 id d1 i f vsub zcd pin current comparator out put (reset) 1 shot out put (valley signal set) t1 t2 t3 t4 60mv fig.2 waveform in basic operation fig.1 schematic circuit diagram in basic operation bottom detection 1 shot (290ns) bottom skip control driver level shift zcd c 1 r 1 rs 2 3 sq r 1 5 out is fb d1 vds vsub if set rset current comparator q1 cd
an-064e rev.1.1 april 2011 19 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 9. description of the function (the values in the following description are typical values unless otherwise specified.) (1) steady-state operation, bottom-skip operation, and burst operation ? steady-state operation, bottom-skip operation the on/off cycle, which is from turn-on of the driver signal to the end of fly-back voltage, is detected, and bottom-skip operations are performed at the time detected. since the relation between the on/off width and the number of times of bottom skip operations is exhibited in the hysteresis as shown in fig. 4, waveform fluctuations can be prevented and transformer audible noise can be decreased. fig. 5 shows the change image of the switching frequency to the output electric power. fig. 6 shows the change image of the on/off width. vds bottom signal t<10us out pulse 10us9us out pulse 9us>t>8us 8us>t>7us t<7us load decrease 1st 3rd 4th 2nd t>14us 1th on-off width fig.3 steady-state operation and bottom-skip operation timing chart
an-064e rev.1.1 april 2011 20 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ fig.4 on/off width at transfer to bottom-skip operation fig.5 change image of switching frequency fig.6 change image of on/off width 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 on-off width [us] b o t t o m c o u n t [ t h ] load decrease load increase 11.67us 0 50 100 150 0 20 40 60 80 100 output power [w] s w i t c h i n g f r e q . [ k h z ] load decrease load increase bottom skip 1st 2nd 3rd 4th 1st 2nd 3rd 4th 0 5 10 15 20 0 20 40 60 80 100 output power [w] o n - o f f w i d t h [ u s ] load decrease load increase bottom skip 1st 2nd 3rd 4th 1st 2nd 3rd 4th
an-064e rev.1.1 april 2011 21 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ ? burst operation when the fb pin voltage decreases to lower than the pulse shutdown threshold voltage, switching is stopped. on the contrary, if the fb voltage increases to higher than the pulse shutdown threshold voltage, switching is resumed. overshoot and undershoot of the fb pin voltage occur over and under the pulse shutdown threshold voltage for mode switching. continuous pulses are issued during this overshoot period, and long-cycle burst frequency is obtained during the undershoot period. the pulse shutdown threshold voltage is switched to 0.45 v when input voltage is low, whereas it is switched to 0.35 v when input voltage is high, as input voltage compensation. fig.7 burst operation at light load vthfb01=0.45v vthfb02=0.35v fb pin voltage pulse stop voltage out pin switching pulse heavy load light load (burst switching)
an-064e rev.1.1 april 2011 22 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (2) startup circuit and auxiliary winding voltage when power is turned on, the current supplied from the startup circuit to the vcc pin through the vh pin charges the capacitor connected to the vcc pin to increase voltage. if the vcc pin voltage exceeds on threshold voltage 14 v or 10 v, the internal operation power is turned on, and the ic is start operating. at this time, if the voltage supplied from the auxiliary winding is higher than 9 v, the startup circuit is operated at the time of startup only, and after the startup, auxiliary winding voltage is used as power supply. meanwhile, if the auxiliary winding voltage is lower than 9v, the ic maintains operation within the vcc range between 9v and 11v by on/off of startup circuit. vcc startup circuit switching 11v 9v 8v 14v ac sw fig.8 startup and shutdown (when auxiliary winding voltage is higher than 9v) vcc startup circuit switching 11v 9v 8v 14v ac sw fig.9 startup and shutdown (when auxiliary winding voltage is lower than 9v)
an-064e rev.1.1 april 2011 23 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (3) operation under overload using the built-in timer, the duration of overload status of 200 ms or longer is detected, and switching is stopped forcibly. if the switching is stopped, supply of current from the auxiliary winding is eliminated, and the vcc pin voltage reduces to 9 v or lower, the startup circuit is operated, and the vcc is maintained within the range from 9 v to 11 v. if overload status continues for 200 ms or longer, the switching is stopped, and then after the elapse of 1400 ms, the switching is resumed. at that time, if the overload status persists, start and stop switching are repeated. if the load returns to normal, normal operation is resumed. at the time of startup, it is necessary to increase the output voltage to the setting within the timer setting of 200 ms. since the operation is performed automatically using the built-in timer, even if external power is input directly to the vcc pin, operation is reset automatically. 11v 9v 8v 200ms 3.3v 200ms 1600ms 200ms 1600ms 14v 200ms 1600ms vcc pin voltage start up circuit on/off signal olp timer output output pin switching pulse fb pin voltage olp timer operation active disabled on off normal load over load normal load fig.10 operation under overload (automatic reset type)
an-064e rev.1.1 april 2011 24 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (4) overvoltage protection function on the secondary side in case of overvoltage of output, the voltage of the auxiliary winding also rises. the zcd pin has the function of cycle-by-cycle detecting the voltage of the auxiliary winding of transformer. if the state in which the zcd pin voltage is 6.0 v or higher continues for 60 ? s or longer, switching is stopped and the operation is latched-off. this state is maintained until the input voltage is interrupted, and the vcc decreases to the off threshold voltage of the uvlo. for example if switching is made at 40 khz, 60 ? s ? 40 khz = 2.4: detection of twice or more is required. (5) external latch-off function by pulling up the zcd pin to 6.0 v or higher for 60 ? s or longer, the ic is latched-off. this state is maintained until the input voltage is interrupted and vcc decreases to the off threshold voltage of the uvlo. (6) compensating each threshold level by high-line voltage detection (FA5640/fa5641) by detecting the peak voltage of the vh pin, each threshold level is switched to compensate for high/low line voltage. the threshold level to be switched by high-line voltage include the pulse shutdown fb voltage, which is related to the pulse mode switching load, and the maximum input threshold voltage, which is the overcurrent limit level of the is pin. (7) minimum switching frequency limitation and maximum on width limitation the maximum on pulse width is limited to 24 ? s to reduce the audible noise of the transformer when it is started and stopped. in addition, fa5641 is integrated in minimum switching frequency that is limited at 25 khz to reduce audible noise more. see 10. (9) ?other advice on designing? for details. (8) switching of overload protection levels due to external signal detection by pulling up the voltage of is pin to higher than the is pin standby detection voltage during the off period of the mosfet using external signals, overload protection levels can be switched. more specifically, by switching the maximum input threshold voltage, which is the overcurrent limit level of the is pin, the power can be limited to approximately 1/7 of the overload protection level of normal operation. this function is useful for limiting the power in standby mode, for example. (9) restart operation if the mosfet cannot be turned on based on bottom detection of the zcd pin at the time of startup, restart operation is performed using a timer to forcibly turn on the mosfet. if the condition in which the out is low (mosfet is off) and the voltage of the zcd pin is below to input threshold voltage (vthzcd2) 150 mv or lower, the timer starts counting and the mosfet is turned on when the timeout from the last zcd trigger.
an-064e rev.1.1 april 2011 25 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 10. how to use each pin and advice for designing (the values that appear in the following description are typical values, unless otherwise specified.) (1) pin no. 1 (zcd pin) function ( ) detects the timing that mosfet is turned on. ( )performs latch-off protection by external signals. ( )performs latch-off protection in case overvoltage on the secondary side. how to use ( ) turn on timing detection ? connection method connect the auxiliary winding of the transformer via the cr circuits, r1 and c1 (fig. 11). be careful the polarity of the auxiliary winding. ? operation if the voltage of the zcd pin decreases to 60 mv or lower, the mosfet is turned on. the auxiliary winding voltage fluctuates significantly in both positive and negative voltage at the time of switching. to protect the ic from this voltage fluctuation, a clamp circuit is integrated. if the auxiliary winding voltage is positive, current is fed as shown in fig. 12, and if it is negative, current is fed as shown in fig. 13, to clamp the voltage of the zcd pin. in turning on based on bottom detection of the zcd pin is not possible at the time of startup, for example, restart operation is performed using timer to forcibly turn on the mosfet. if the out is low (mosfet is off) and the voltage of the zcd pin is below to input threshold voltage (vthzcd2) 150 mv or lower, the timer starts counting, and if the time out time from the last trigger (7.6 ? s or 25 ? s), the mosfet is turned on. ( ) latch-off protection by external signals ? connection method pull up the zcd pin by external signals. figure 14 is a typical connection showing the overvoltage on the primary side. (constants are examples. check the operation with the actual power supply unit.) ? operation if the voltage of the zcd pin exceeds 6.0 v, and this state continues for 60 ? s or longer, latch-off operation is performed to stop output switching. once the latch-off operation is started, the vcc voltage is maintained by the startup circuit to continue the latch-off operation. decrease the vcc to the off threshold voltage or lower to reset the latch operation. ( ) latch-off protection at overvoltage on the secondary side ? connection method the same as turn on timing in ( ) ? operation if the output voltage (vo) on the secondary side enters overvoltage state, the auxiliary winding voltage and zcd pin voltage also increase. this ic detects zcd pin voltage elapsed time of 4.5 ? s after mosfet is turned off, and when the zcd pin voltage exceed 6.0v and this states continues for 60 ? s or longer, latch-off operation is performed to stop switching (fig. 15). once the latch operation is started, the vcc voltage is maintained by the startup circuit to continue the latch operation. decrease the vcc to the off threshold voltage of the uvlo or lower to reset the latch operation. 1 30k w 7.5v zcd c 1 r 1 cd r zcd fig.11 zcd pin circuit 1 30k w 7.5v zcd clamp current fig.12 clamp circuit (when auxiliary winding is in positive voltage.) 1 30k w zcd clamp current -0.8v fig.13 clamp circuit (when auxiliary winding is in negative voltage.) 1 6 vcc zcd 8.2k 2.2k 2.2k 24v 0.47uf ? ^ fig.14 primary side overvoltage protection circuit
an-064e rev.1.1 april 2011 26 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ advice for designing immediately before the mosfet is turned on, the mosfet drain-source voltage is resonated due to the transformer inductance and the resonance capacitor cd. adjust c1 to allow the mosfet to be turned on at the valley of this resonance (see figs. 16 and 17). since overvoltage threshold voltage is 5.7 v (min.), select resistance r1 not to allow the zcd pin voltage to exceed 5.7 v, or allow the zcd pin current to exceed the absolute maximum rating, in normal operation, ensuring that the following calculation formulae are satisfied. v zcd =v thovp vn s / v ovp where, v zcd : zcd pin voltage at normal operation v thovp : zcd pin overvoltage threshold level (6 v) vn s : line voltage secondary winding of transformer at normal operation (vo ? vf) v ovp : output voltage to be subjected to overvoltage latch-off vn sub =vn s n sub / n s where, vn sub : line voltage of auxiliary winding of transformer n sub : number of turns of auxiliary windings of transformer n s : number of turns of secondary windings of transformer using the formula v zcd =vn sub r zcd / (r 1 r zcd ) , r1 is found to be r 1 =vn sub r zcd / v zcd r zcd where, r zcd : internal resistance of zcd pin (30 k ? ) if the capacitance of capacitor c1 is to be increased to prevent malfunction due to surge, for example, it may be necessary to decrease the resistance r1 for bottom detection of the auxiliary winding. if the overvoltage detection level decreases as a result, add resistance r2 for adjustment. in this case, the following formula applies: r 1 = r zcd r 2 r zcd +r 2 vn sub v zcd 1 since the source current of the zcd pin input current (absolute maximum rating) is ? 2.0 ma, the following formula must be satisfied at the same time: r 1 > 2v ac(max) n sub / n p / i sozcd where, i sozcd : zcd pin input current (source current = ? 2.0 ma) generally, r1 is around several tens k ? , whereas c1 is around several tens pf. if timing of bottom detection is ok, c1 need not be connected. add schottky diode between zcd-gnd as shown in figure 17 when the terminal zcd input current is not filled even if r1 is appropriately adjusted. if r1 and c1 constants are not appropriate, overvoltage protection may not function properly. figure 18 shows the zcd pin waveform at the time of overvoltage protection. with the upper zcd pin waveform, overvoltage on the secondary side is detected properly, and latch-off is performed by fault protection. meanwhile, with the lower zcd pin waveform, protective function is not operated because the threshold voltage is not reached in 4.5 ? s. in this case, adjust r1 and c1. vo zcd pin 0v 0v 6.0v 4.5us 60us latch fig.15 zcd pin waveform at overvoltage on the secondary side vds fig.16 vds waveform 1 30k w 7.5v zcd c 1 r 1 cd r zcd v ns v o v f ns np nsub v nsub v zcd r 2 d1 fig.17 zcd pin resistance r1 calculation
an-064e rev.1.1 april 2011 27 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (2) pin no. 2 (fb pin) function ( )input feedback signals from the error amplifier on the secondary side. ( )detects overload status. ( )stops switching for burst operation. how to use ( ) feedback signal input ? connection method connect the optocoupler corrector to this pin will allow reguration. at the same time, to prevent generation of noise, connect a capacitor in parallel to the optocoupler (fig. 19). ? operation pin no. 2 is biased from the ic internal power supply via the resistance. the fb pin voltage is level-shifted and input into the current comparator to provide the threshold voltage of the mosfet current signals to be detected with the is pin. ( ) overload detection ? connection method the same as the feedback signal input in ( ). ? operation in case of overload, the output voltage decreases to lower than the setting, therefore the fb pin overshoots to the high side. this state is detected to judge overload status. the threshold voltage for overload judgment is 3.5 v. by the automatic recovery function, overload status brings about hiccup operation, and once the overload state is reset, operation is automatically resumed. see 9. (3) ?operation under overload? for details of operation. ( ) stopping switching for burst operation ? connection method the same as feedback signal input in ( ) ? operation fb pin voltage decreases under light load. if this voltage decreases to threshold voltage of stopping on-pulse or lower, switching is stopped, and switching is resumed if the voltage increases to the threshold voltage of stopping on-pulse or higher. by repeating this operation, burst operation is achieved. to undershoot the fb pin voltage significantly at the time of burst operation, the internal fb pin resistance is switched (fig. 19). to compensate the dependence of load point for entering burst operation on the high-line voltage, the pulse shutdown fb threshold voltage is switched to 0.45 v for high line voltage, and 0.35 v for low line voltage. 0v 6.0v 6.0v 0v 4.5us fig.18 zcd pin waveform at overvoltage advice for designing the fb pin provides threshold voltage of the current comparator. if noise is added to the pin, output pulse fluctuation may result. to prevent generation of noise, a capacitor having the capacitance of approximately 1000 pf to 0.01 ? f is connected for use as shown in fig. 19. 2 24k w 4.8v fb 1000pf 0.01uf 216k w / 108k w fig.19 fb pin circuit
an-064e rev.1.1 april 2011 28 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (3) pin no. 3 (is pin) function ( ) detects and limits the current value of the mosfet. ( ) switches the maximum threshold voltage of current limit by external signals. how to use ( ) current detection and current limiting ? connection method connect a current detecting resistor rs between the mosfet source pin and the gnd. the current signals of the mosfet generated in the resistor are input (fig. 20). ? operation the current signals of the mosfet input to the is pin is then input to the current comparator, and if it reaches the threshold voltage determined by the fb pin, the mosfet is turned off. this fb pin voltage fluctuates due to the feedback circuit from the output voltage to control the mosfet current. in addition, since the maximum input threshold voltage is also input to the current comparator, the mosfet current is limited by the current equivalent to this voltage even in an emergency state such as transient state at the time of startup or overload status. if overload state continues, the latch-off stop is performed by the overload protection function. generally, the output current value that is stopped in the latch-off mode varies depending on the high-line voltage, and there may be a case in which the higher the line voltage, the larger the output current that is stopped in the latch mode. to compensate the dependency of overload detection level on the line voltage, the maximum input threshold voltage is switched between 0.5 v (low line voltage) and 0.45 v (high line voltage). ( ) switching of current limiting maximum threshold voltage by external signals ? connection method as shown in fig. 21, a diode, current limiting resistor, transistor switch, optocoupler, etc. are added between the auxiliary winding and the is pin. ? operation while the mosfet remains on, mosfet current signals are kept input to the is pin for comparison with the threshold voltage that is determined by the fb pin. with this ic, is pin voltage level is detected during this off period. by increasing the is pin voltage to 0.55 v, which is the is pin standby detection voltage, or higher within 2 ? s after the mosfet is turned off, the maximum input threshold voltage of the is pin is switched. in this case, the detection level is decreased to approximately 1/7 of that of normal operation. but it is necessary to confirm output power in actual power supply unit because the output power may vary with specification of transformer and circuit constant. for example, the power of the power supply is limited in standby mode. specifically, the maximum input threshold voltage is switched between 0.15 v (low line voltage) and 0.1 v (high line voltage). if low signals are input from the external signal, transistor tr1 and the optocoupler are set to off, and transistor tr2 is brought into continued state, and the is pin is subjected to the effect of the auxiliary winding voltage. the auxiliary winding voltage remain positive while the mosfet is set to off, and negative while it is set to on, and thanks to the function of diode d1, the is pin voltage is increased to positive side only during the period in which the mosfet remains off. 3 rs is current comparator fig.20 is pin circuit is vcc rs 6 3 vout d1 d2 external switch signal tr2 tr1 r3 normal standby standby detection voltage 0.55v(typ.) is pin delay 2.0us fig.21 power limiting circuit and waveform at standby detection
an-064e rev.1.1 april 2011 29 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ advice for designing (1) insertion of a filter since this ic has a leading edge blanking (minimum on width: 290 ns), malfunction due to surge current generated at the mosfet is switched on does not occur. however, if the surge current generated at the leading edge of out is large, or external noise is added, malfunction may occur. in such cases, add a cr filter to the is pin as shown in fig. 22. the filter constant depends on the magnitude of the noise, but as the time constant of ris ? cis, about 500 ns or less is recommended. note, however, the overload detection level and the load level of starting burst operation may vary, thus audible noise may be generated or standby power may vary. pay special attention to the above phenomena. (2) burst operation point adjustment 1 under light load if burst operation is started under heavy load, the audible noise may be generated at transformer. to decrease the burst point slightly, add resistor r4 between the is pin and the out pin (fig. 23). if r4 is connected, the positive bias voltage is applied to the is pin voltage when the mosfet is turned-on, and consequently, the fb pin voltage also remains high level. since burst operation occurs if the fb pin voltage decrease to 0.45 v (at low line voltage) or lower, burst operation does not tend to occur if the fb pin voltage remains high. even if a resistor is added between the is pin and the out pin, the effect of resistor r4 may not be obtained if ris is small. in this case, decrease cis and increase ris, while fixing the time constant of the filter (ris = 470 ? is recommended when r4 is added). note, however, that the standby power may increase, or overload detection level may vary. with this ic, though the dependency of overload detection level on line voltage has been compensated, this ratio may deviate. confirm there is no problem in application enough. (3) burst operation point adjustment 2 under light load to allow bust operation to occur under slightly heavier load, thus to improvement the efficiency under light load, on condition that there is no transformer audible noise problem, add resistor r5 between the is pin and the out pin (fig. 24). note, however, that the overload detection level varies in this case also. with this ic, though the dependency of overload detection level on line voltage has been compensated, this ratio may deviate. confirm there is no problem in application enough. (4) switching of current limiting maximum threshold voltage by external signals diodes d1 and d2 in fig. 21 can share parts with the diode connected between the vcc pin and the auxiliary winding. while the mosfet is turned-off, the voltage of auxiliary windings is depended on output voltage on the secondary side and ratio of the number of turns of secondary windings and number of turns of auxiliary windings. as the pull-up level of the is pin voltage, determine the value of r3 so that the is pin voltage reaches is pin standby detection voltage 0.55 v, or higher within 2 ? s after the turn off. in this case, if ris is small, the is pin voltage may not increase. therefore, adjust the constant of the filter, following the description in (2) ?burst operation point adjustment 1 under light load.? diode d2 is added to prevent heating of the mosfet in the event diode d1 is short-circuited, causing negative voltage to be applied to the is pin and allowing the on width to increase abnormally. 3 rs is current comparator ris cis fig.22 is pin filter gnd is 3 ris rs cis 5 out r4 4 fig.23 burst operation point adjustment 1 gnd is 3 4 ris r5 rs c1 6 vcc fig.24 burst operation point adjustment 2
an-064e rev.1.1 april 2011 30 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (5) fine adjustment of overload detection level the overload detection level is determined by the value of resistor rs in principle. to fine-tune the level, add resistor r6 as shown in fig. 25 to input the voltage divided by resistors ris and r6 into the is pin. (4) pin no. 4 (gnd pin) function pin no. 4 serves as the basis of the voltage of each part of the ic. (5) pin no. 5 (out pin) function drives the mosfet how to use ? connection method connect pin no. 5 to the mosfet gate (figs. 26, 27, and 28). ? operation while the mosfet remains on, it is in high state, and vcc voltage is output. while the mosfet remains off, it is in low state, and 0 voltage is output. advice for designing connect the gate resistor to limit the current fed to the out pin or prevent vibration of gate pin voltage. adjust the gate resistor not to exceed the ic output current rating of 0.25 a (source) and 0.5 a (sink). (6) pin no. 6 (vcc pin) function supplies for the ic. how to use ? connection method generally, the pin is connected the auxiliary winding of the transformer which is rectified and smoothed (fig. 29). the auxiliary winding that can be connected to the zcd pin can be shared. ? operation set the voltage to be supplied from the auxiliary winding within the 11 to 26 v range (recommended operation condition) in normal operation. since the startup circuit is operated when the vcc pin voltage decreases to the startup current restart voltage, 9 v, or lower, the vcc pin voltage is recommended to be used by 11 v or higher because the startup circuit is not operated. it is also possible to operate the ic not by using the auxiliary winding but using the current supplied from the startup circuit. however, standby power increases and heating of ic also increases in these cases. consequently, to achieve low standby power, it is recommended to supply vcc from the auxiliary winding. at the same time, if the startup circuit only is used for startup, the mosfet to be driven must be selected carefully because there is a limit in current to be supplied. 3 rs is ris cis r6 fig.25 fine adjustment of overload detection level 5 6 4 driver out vcc gnd fig.26 out pin circuit (1) 5 6 4 driver out vcc gnd fig.27 out pin circuit (2) 5 6 4 driver out vcc gnd fig.28 out pin circuit (3) 1 6 vcc zcd c2 c1 r1 fig.29 vcc circuit
an-064e rev.1.1 april 2011 31 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ advice for designing (1) connection of the bypass capacitor since large current is fed to the vcc pin when the mosfet is driven, relatively large noise tends to be generated. in addition, noise is also generated from the current supplied by the auxiliary winding. if this noise is large, malfunction of the ic may result. to minimize the noise that is generated at the vcc pin, add a bypass capacitor c2 (0.1 ? f or higher) adjacent to the vcc pin of the ic, between vcc and the gnd, as shown in fig. 29, in addition to the electrolytic capacitor. (2) adjustment of power supply voltage input range the recommended supplied voltage range is 11 v to 26 v. when the load is light, the vcc pin voltage decreases, whereas when the load is heavy, the voltage increases, thus deviating from the power supply voltage range. in such cases, change the resistor between the vcc pin and the diode to adjust the voltage. also, by adding beads core at the foot of the resistor, voltage fluctuation may be suppressed. if the above methods do not work, it is recommended to change the secondary winding and the auxiliary winding of the transformer to bifilar winding. (3) when power is supplied directly to the vcc pin when directly supplying power to the vcc pin without using vh pin, short-circuit the vh pin and the vcc pin for use. if the vh pin is connected to the gnd, or used in open state, leakage current may be generated. (7) pin no. 7 (n.c.) since this pin is placed adjacent to the high-voltage pin, it is not connected to inside the ic. (8) pin no. 8 (vh pin) function ( ) supplies startup current. ( ) detects and compensates by the high-line voltage. how to use ( ) supply startup current. ? connection method connect the pin to the high-voltage line. in this case, if connection is to be made after rectification, connect it via a resistor of several k ? (fig. 32). on the other hand, if connection is to be made before rectification, connect it to the high-voltage line via a resistor of several k ? and a diode (figs. 30 and 31). ? operation this ic, which integrates a startup circuit having withstand voltage of 500 v, achieves low power consumption. figure 30 presents a typical connection method, in which the vh pin is connected to the half-wave rectification waveform of the ac line voltage. with this method, the startup time is the longest of the three connection methods. in addition, since current supply from the vh pin is interrupted if the ac line voltage is interrupted after the ic enters the latch-off mode, the latch-off mode can be reset in a period of time as short as several seconds. 8 6 start on/off vh vcc fig.30 vh pin circuit (1) with the connection shown in fig. 31, the vh pin is connected to the full wave rectification waveform of the ac line voltage. the startup time of this method is approximately half of that of the half-wave rectification shown in fig. 30. in addition, by interrupting the ac line voltage, the time required for resetting the latch mode is as short as the case shown in fig. 30. but this connection method may malfunction when the model which is integrated line voltage compensation is used, so fa5642 only is recommended this connection. 8 6 start on/off vh vcc fig.31 vh pin circuit (2) startup circuit on/off signal startup circuit on/off signal
an-064e rev.1.1 april 2011 32 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ with the method shown in fig. 32, the vh pin is connected after the ac line voltage is rectified and smoothed. the startup time of this method is the shortest of the three connection methods. however, since the voltage charged in the bulk capacitor is applied to the vh pin even if the ac line voltage is interrupted after the ic enters the latch-off mode, longer time is required to reset the latch-off mode. note that several minutes are required to reset the latch-off mode after the ac line is interrupted, although the duration depends on the operating conditions. if power is turned on, the capacitor connected to the vcc pin is charged due to the current supplied from the startup circuit to the vcc pin via the vh pin, and the vcc voltage increases. when the on threshold voltage of 14 v of the low-voltage malfunction prevention circuit (uvlo) is exceeded, the internal supply is started to operate the ic. if vcc is not supplied from the auxiliary winding, the startup circuit is stopped. meanwhile, if power is not supplied from the auxiliary winding, the current supplied from the startup circuit is used for the normal operation of the ic. if vcc is supplied only from the startup circuit, without the supply from the auxiliary winding, the standby power increases, and the heating of the ic may increase. consequently, to keep the standby power at low level, it is desirable to supply vcc from the auxiliary winding. at the same time, if the startup circuit only is used for startup, there is a limit in current to be supplied. consequently, the mosfet to be driven must be selected carefully. the current fed from the vh pin to the vcc pin is approximately 8 ma when vcc = 6.5 v. note that when vcc = 0 v, the current decreases to 0.7 ma to cope with abnormal state such as short circuit between pins. ( ) the peak voltage of the line voltage is detected to subject it to high/low line voltage compensation. ? connection method the same as the method of supplying startup current in (i) ? operation if voltage after rectification is input to the vh pin, each threshold level is switched at 226 v when the vh pin voltage is increasing, and 212 v when it is decreasing. if half-wave and full-wave rectification waveforms are input, it is switched at 160 vrms. the input detection switching delay time is 30 ms. the threshold level for switching based on input voltage include the pulse shutdown fb voltage, which is related to the burst operation, and the maximum input threshold voltage, which is the overload limit level of the is pin. 8 6 start on/off vh vcc fig.32 vh pin circuit (3) advice for designing (1) startup resistor to prevent damage to the ic due to surge voltage of the ac line, it is recommended to connect a startup resistor whose resistance within the 2 k ? to 10 k ? range to the vh pin in series. startup time or startup voltage cannot be adjusted using this startup resistor. note that a resistor having too large resistance may result in inability to startup. (2) to supply power directly to the vcc pin to supply power directly to the vcc pin without using a vh pin, short-circuit the vh and the vcc pins. if the vh pin is connected to the gnd or used in open state, leakage current may be generated.
an-064e rev.1.1 april 2011 33 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ (9) other advice on designing (1) surge that occurs at startup due to the minimum switching frequency limiting our lineup includes the one that the minimum switching frequency and the maximum on width are set with this ic to reduce audible noise at the time of starting /stopping. however, due to this minimum switching frequency function, there is a period in which the ic is operated in continuous conduction mode at startup, which may result in increased surge voltage of the diode on the secondary side. please consider using the one that this minimum switching frequency limiting function was not integrated if the serge of the diode is a problem. (2) switching frequency at the time of bottom skip this ic detects on/off width using the zcd pin, thus controlling the number of times of bottom skips. bottom skip is performed up to the point where the ic is turned on at the fourth bottom depending on the load. at this time, depending on the specifications of the power supply or design conditions of the transformer, the switching frequency at the time of bottom skip may be decreased to 40 khz or lower. if this frequency interferes with other devices, causing problems, for example, adjust the resonance capacitor connected between the drain and the source of the mosfet. if the capacitance is reduced, the resonance frequency increases, allowing the switching frequency at bottom skip to increase. (3) preventing malfunction due to negative voltage of the pin if large negative voltage is applied to each pin of the ic, the parasitic devices within the ic may be operated, thus causing malfunction. confirm that the voltage of -0.3 v or less is not applied to each pin. the vibration of the voltage generated after the mosfet is turned-off may be applied to the out pin through the parasitic capacitance, resulting in a case in which negative voltage is applied to the out pin. in addition, negative voltage may be applied to the is pin due to the vibration of surge current generated at the turn-on of the mosfet. in such cases, connect a schottky diode between each pin and the gnd. the forward voltage of the schottky diode can suppress the negative voltage at each pin. in this case, use a schottky diode whose forward voltage is low. figure 33 is a typical connection diagram where a schottky diode is connected to the out pin. (4) loss calculation to use the ic within its rating, it is necessary to confirm the loss of the ic. however, since it is difficult to measure the loss directly, the method of confirming the loss by calculation is shown below. if the voltage applied to the vh pin is defined as vvh, the current fed to the vh pin during operation as ivhrun, power supply voltage as vcc, supply current as iccop1, gate input charge of the mosfet to be used as qg, and switching frequency as fsw, the total loss pd of the ic can be calculated using the following formula. a rough value can be found using the above formula, but note that pd is slightly larger than the actual loss value. also note that each specific characteristic value has temperature characteristics or variation. example: if the vh pin is connected to a half-wave rectification waveform with ac 100 v input, the average voltage to be applied to the vh pin is approximately 45 v. in this state, assume that vcc = 15 v, qg = 80 nc, and fsw = 60 khz (when tj = 25 ? c). since ivhrun = 30 ? a and iccop1 = 0.85ma from the specifications, the standard ic loss can be calculated as follows: p d 1 5 v x ( 0 . 8 5 m a + 8 0 n c x 6 0 k h z ) + 4 5 v x 30a 86.1mw gnd out 5 4 sbd rg fig.33 negative charge prevention circuit
an-064e rev.1.1 april 2011 34 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 11. precautions for pattern design (1) precautions for pattern design in order to prevent the malfunction of the control ic (unstable voltage, unstable waveform, latch-off, etc.) caused by the surge voltage (noise) when a current is applied to the pattern on the minus side because of a principal current, a lightning surge test, an ac line surge test, and a static electricity test, consider the following contents when designing the pattern. the power supply has the following current paths: 1) a principal current applied from the electrolytic capacitor to the primary winding of the transformer, the mosfet, and the current sensing resistor after ac power supply rectification 2) a rectified current applied from the auxiliary winding of the transformer to the electrolytic capacitor; a drive current applied from the electrolytic capacitor to the control ic and the mosfet gate. 3) a control current of the control ic for output feedback or the like 4) filter and surge currents applied between the primary and secondary sides ? s e p a r a t e t h e p a t t e r n s o n t h e m i n u s s i d e i n 1 ) t o 4 ) t o a v o i d i n t e r f e r e n c e f r o m e a c h o t h e r . ? t o r e d u c e t h e s u r g e v o l t a g e o f t h e m o s f e t , m i n i m i z e t h e l o o p o f t h e p r i n c i p a l c u r r e n t p a t h . ? i n s t a l l t h e e l e c t r o l y t i c a n d f i l m c a p a c i t o r s b e t w e e n t h e v c c p i n a n d t h e g n d i n a c l o s e s t p o s i t i o n t o e a c h p i n i n o r d e r t o connect them at the shortest distance. ? i n s t a l l t h e f i l t e r c a p a c i t o r s f o r t h e f b , i s , a n d z c d p i n s a n d t h e l i k e i n a c l o s e s t p o s i t i o n t o e a c h p i n i n o r d e r t o c o n n e c t t h e m at the shortest distance. especially, connect the patterns on the negative side of the fb and is pins to the gnd pin of the ic, separately from other patterns, keeping the wiring as short as possible. ? a v o i d i n s t a l l i n g t h e c o n t r o l c i r c u i t a n d p a t t e r n w i t h h i g h i m p e d a n c e d i r e c t l y b e l o w t h e t r a n s f o r m e r . 5 6 ac input output cn2 1 4 8 7 6 5 1 2 3 4 lat fb is gnd outvcc(nc)vh principal current drive current filter and surge current control current fig.34 pattern design image
an-064e rev.1.1 april 2011 35 FA5640/41/42 fuji electric co., ltd. http://www.fujielectric.co.jp/products/semiconductor/ 12. example of application circuit the typical application circuit shown here provides specifications common to each ic series. 2 5 7 8 13,14,15,16 9,10, 11,12 1 ac85 to 264v 24v / 4a 96w f1 0.47u 4a,8mh 0.22u hs1 d10xb60h 600v,1a 4.7k 200v,1a 22 47 470u 0.1u 100k 1kv,0.5a t1 np:ns:nb=40:12:10 lp=176uh 2200p tr1 fmv11n70e 700v/11a 0.1 10k 400v,1a 4.7 100u 1000ppc1b1000p 10p ic1 470p 22 yg906c2r 200v/20a 1500u 1500u c23 0.1u hs2 0.1u 1.5k 4.7k pc1a tlp421f gr 130k 0.047u47k 15k cn2 cn1 ha17432hup 2200p 2200p 56k fb 4.7k fb 220p 470 p2 p1 p3 p4 rv1 3 5 1 2 3 4 1m 1m 8 7 6 5 1 2 3 4 zcd fb is gnd outvcc(nc)vh 0.1u 510 5.1k 3 4 39k sbd sbd sbd note: this application circuit is a reference material for describing typical usage of this ic, and does not guarantee the operation or characteristics of the ic.

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