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rev. 1.00 1 may 27, 2011 rev. 1.00 pb june 21, 2011 HT7A3942 high performance current mode pwm controller feature ? high performance, low cost current mode pwm controller especially designed for energy star 2.0 ? high-voltage cmos process with excellent esd protection (>3kv) ? very low startup current (<20a) and operating current ? 5% trimmed oscillator for precise frequency control ? non-audible-noise green mode control ? leb (leading-edge blanking) on cs pin ? internal slope compensation ? programmable switching frequency ? internally trimmed reference with uvlo (under v oltage lockout) ? cycle-by-cycle current limiting ? build-in short-circuit-protection(scp) for short-circuit and over-load condition ? 8-pin sop package applications ? switching ac-dc adaptor ? open frames switching power supply ? lcd tv general description the HT7A3942 is a high performance, low cost current m ode p wm controller for providing necessary feature to implement of f-line application. by opt imizing fo r t he e nergy st ar 2 .0 sp ec., t he power supply unit (psu) implemented using the HT7A3942 can satisfy the ener gy star no-load mode stand-by power standard, which is less than 0.3w within all nameplate output power range of 0~250w. internally implemented circuits include a trimmed oscillator for precise frequency control, a temperature-compensated v oltage reference, slope c ompensation, l eading-edge b lanking, a nd a patented non-audible noise green mode control scheme. the HT7A3942 features a range of various protection functions such short-circuit protection (scp , which can a lso be use d fo r ove r-load prot ection, ol p), cycle-by-cycle current limiting and under v oltage lock-out (uvlo). application circuits emi filter flyback converter ht 7a 3942 rt gd cs vcc comp vref gnd 0.1 uf 10 k fod 817 tl 431 25k 95 k gnd vout current sense voltage sense
rev. 1.00 2 may 27, 2011 HT7A3942 block diagram pin assignment 32v uvlo 14v / 8v internal bias & vref green mode osc slop compensation pwm 2r r ocp 1v leb 350ns scp s r q driver stage vref vcc gd gnd vcc rt comp cs pin description pin no. pin name description 1 comp voltage feedback pin. connected to a photo-coupler for close-loop control. 2 n.c no connection 3 cs a voltage proportional to inductor current is connected to this input. the pwm generator uses this voltage information to terminate the output switch conduction. 4 rt the oscillator frequency is programmed by connecting a resistor rt between this pin and ground. a maximum frequency of 500khz is possible. 5 gnd combined control circuitry and power ground. 6 gd power mosfet gate driver output. 7 vcc positive supply. 8 vref reference output. absolute maximum ratings supply v oltage vcc ................................................................................................................................ -0.3v~30.0v comp , rt, cs pins ................................................................................................................................... -0.3v~5.5v junction t emperature .......................................................................................................................................... 150c operating ambient t emperature ............................................................................................................... -40c~85c storage t emperature range .................................................................................................................... -65c~150c package thermal resistance (8-pin sop) ..................................................................................................... 160c/w esd protection: human body model ......................................................... .............................................................................. 3kv machine model ......................................................... ................................................................................... 200v note: these are stress ratings only . stresses exceeding the range specifed under absolute maximum ratings may cause substantial damage to the device. functional operation of this device at other conditions beyond t hose l isted i n t he sp ecifcation i s n ot i mplied a nd p rolonged e xposure t o e xtreme c onditions m ay a ffect device reliability.
rev. 1.00 3 may 27, 2011 HT7A3942 electrical characteristics unless otherwise stated, this specifcations apply for 0c ta 70c, v cc =15v, rt=10k w symbol parameter test condition min. typ. max. unit supply voltage (vcc pin) i st startup current v cc =12.9v 12 30 m a i cc operating current v comp =0v 2.0 3.0 ma v comp =3v 2.5 ma v tl uvlo (off) 7 8 9 v v th uvlo (on) 13 14 15 v reference section v ref output voltage tj = 25c, i o = 1ma 5.5 v ?v ref line regulation 12v v cc 25v 3 20 mv ?v ref load regulation 1ma i o 10ma 4 25 mv current sensing (cs pin) v cs(off) maximum input voltage, vcs(off) 0.9 1.0 1.1 v t leb leading edge blanking time 350 ns delay to output 100 ns oscillator (rt pin) f osc oscillator frequency tj=25c, rt=10k w 49 52 55 khz ?f osc ?t a temp. stability -40c ~105c 5 % ?f osc ?v ref voltage stability v cc =10v~25v 0.2 1.0 %/v d max maximum duty 75 % gate drive output (gd pin) v ol output low level v cc =15v, isink=20ma 1 v v oh output high level v cc =15v, isource=20ma 9 v t r rising time tj=25c, load capacitance=1nf 50 150 ns t f falling time tj=25c, load capacitance=1nf 50 150 ns voltage feedback (comp pin) i sink short circuit current v comp =0v 1.5 2.2 ma v comp open loop voltage comp pin open 5.5 v scp (short circuit protection) v comp scp trip level v comp (scp) 4.7 v scp delay time (see note) f s =52khz 40 ms 1rwh 7khvh 3dudphwhuv dowkrxjk jxdudqwhhg duh qrw whvwhg lq surgxfwlrq
rev. 1.00 4 may 27, 2011 HT7A3942 typical performance characteristics 11 .5 12 12 .5 13 13 .5 14 14 .5 15 15 .5 - 40 - 20 0 20 40 60 80 100 120 temperature ( degree c ) uvlo (on)(v) figure 1. uvlo (on) (v) vs. temperature 47 48 49 50 51 52 53 54 55 56 57 - 40 - 20 0 20 40 60 80 100 120 temperature ( degree c ) frequency (khz) figure 3. frequency vs. temperature 4.4 4. 45 4.5 4. 55 4.6 4. 65 4.7 4. 75 4.8 4. 85 4.9 - 40 - 20 0 20 40 60 80 100 120 temperature ( degree c ) vcomp (v) figure 5. vcomp for scp vs. temperature 6 6.5 7 7.5 8 8.5 9 9.5 10 - 40 10 60 110 temperature ( degree c ) uvlo (off)(v) figure 2. uvlo (off)(v) vs. temperature 47 48 49 50 51 52 53 54 55 56 57 11 13 15 17 19 21 23 25 vcc (v) frequency (khz) figure 4. frequency vs. vcc 15 17 19 21 23 25 27 29 31 11 13 15 17 19 21 23 25 vcc (v) green mode frequency (khz) figure 6. green mode frequency vs. vcc
rev. 1.00 5 may 27, 2011 HT7A3942 application information operation overview the ht 7a3942 i s a n e xcellent, l ow powe r of f-line pwm controller . w ith a high degree of functional integration, the external component requirement is greatly reduced resulting in excellent performance/ cost ratios. the device integrates many enhanced features s uch as a n on-acoustic-noise g reen m ode osc illator, int ernal sl ope com pensation, int ernal leading-edge blanking, short-circuit protection and a wide industrial operating temperature range (-40 c to 85 c ). the device is designed for primary side control / secondary side feedback applications and is optimized for the ener gy-star 2.0 specifcation, this ens ures that any eps (external p ower s upply) implemented using the HT7A3942 can fully satisfy the energy star 1.1/2.0 stand-by (no-load) criteria. energy consumption criteria for no-load nameplate output power (p no ) maximum power in no-load ac-ac eps ac-dc eps 0 to < 50 watts 0.5 watts 0.3 watts 50 to 250 watts 0.5 watts 0.3 watts table 1. energy star 2.0 no-load criteria ultra low stand-by power for energy star 2.0 and later energy star requirement the device contains many advanced control schemes for low stand-by power like tiny operating/stand- by current, green mode for light-load, etc. by c hoosing a n a ppropriate st and-by re sistor (a s shown in figure 7), eps implemented by the device can fully satisfy the energy star 2.0 no-load criteria. figure 7. stand-by resistor base on device feld test demo board results, for the full-range (1 15v, 230v v ac) input, the stand-by power will remain less than 0.3w@pno=60w(as shown in t able 2).this is within the ener gy star 2.0 criteria. input range stand-by power demo board input condition (p no =60 watts) 115v v ac < 0.3w 230v v ac < 0.3w table 2. demo board stand-by power results advanced precise-oscillator for green- mode switching and non-acoustic noise requirement a t rimmed precise green mode oscillator is implemented in the device to enhance the conversion ef ficiency under conditions of light loads. as the da ta shown i n fi g. 8, t he e ffciency di fference of t he traditional current mode pwm controller between light loads and heavy loads is more than 8%, while t he a verage e fficiency i s onl y 82% , t he e fficiency dif ference of the HT7A3942 is only 1%, while average effciency is up to 87.5%. figure 8. effciency comparison between HT7A3942 & traditional current mode pwm controller (measured at HT7A3942 demo board)
rev. 1.00 6 may 27, 2011 HT7A3942 the gre en mode osc illator t ypes suppli ed by ot her pw m c ontroller pr oviders a re pl agued by t he problems of acoustic-noise. this is because, under the conditions of light loads, the frequency will keep de creasing t hrough hum an ac oustic ra nge (from 20hz to 20khz), these audio frequencies may create audible noise in the transformer . holtek s HT7A3942 patented green mode oscillator designed using an a dvanced non-acoust ic noi se schem e t o pre vent t he ge neration of fre quencies i n t he a udio fre quency band, thus eliminating any transformer noise. figure 9. oscillator behavior compared with HT7A3942 and other green mode pwm controller under voltage lockout (uvlo) an uvl o c omparator i s i mplemented i n t o e nsure that the device is fully functional before the output st age i s e nabled. as sh own i n fi g. 1 0, a h ysteresis is provided to prevent the pwm controller from sh utting d own d uring a ny v oltage d ips wh ich m ight occur during startup process . the turn-on and turn- of f threshold levels are set at 16.0v and 10.0v , respectively . figure 10. uvlo scheme and start-up current current sense and leading-edge blanking (leb) a leading-edge blanking scheme is integrated in the device to prevent false triggerin g due to feedback current spi kes whi ch m ay appea r on t he cs pin, further eliminate the need for r-c filter which is alw ays a requirement in the traditional current mode pwm controller applications. figure 11. leb with r-c filter removed
rev. 1.00 7 may 27, 2011 HT7A3942 internal slope-compensation an i mportant i ssue wi th t he c urrent m ode c ontrol schemes is the instability due to sub-harmonic oscillation when the duty-cycle > 50%. t o prevent this problem from occurring, a sl ope-compensation fu nction i s a lways n ecessary. in t raditional c urrent m ode pw m cont roller a pplication, m any e xternal components are necess ary for s lope-compensation function, but in HT7A3942 the internal slope- com pensation e liminates t he ne ed for t hese e xternal components resulting in simplified the application circuit design. short-circuit protection (scp) and over-load protection (olp) to p rotect a ll t he d evices of a syst em f rom be ing damaged under over load or short circuit conditions, a sm art scp func tion i s i mplemented i n t he de vice. here the feedback system will force the voltage loop to move toward a saturat ion value and then pull up the voltage on the comp pin. whenever the vcomp increases to the scp threshold of 4.7v and remains there for longer than 40ms, the protection scheme will a ctivate a nd t hen t urn of f t he ga te out put t o st op t he switching of power circuit. by using such a protection mechanism, the average input power can be reduced to a very low level so that the component temperature a nd st ress c an b e c ontrolled wi thin sa fe o perating levels. figure 12. scp function behavior oscillator frequency tuning by choos ing an appropriate value of an external resistor between the r t pin and gnd, a suitable operating frequency can be generated. the relationship between the value of r t and the operating frequency is provided in the figure 13. figure 13. rt resistor value vs. operating frequency
rev. 1.00 8 may 27, 2011 HT7A3942 package information 8-pin sop (150mil) outline dimensions ms-012 symbol dimensions in inch min. nom. max. a 0.228 D 0.244 b 0.150 D 0.157 c 0.012 D 0.020 c' 0.188 D 0.197 d D D 0.069 e D 0.050 D f 0.004 D 0.010 g 0.016 D 0.050 h 0.007 D 0.010 0 D 8 symbol dimensions in mm min. nom. max. a 5.79 D 6.20 b 3.81 D 3.99 c 0.30 D 0.51 c' 4.78 D 5.00 d D D 1.75 e D 1.27 D f 0.10 D 0.25 g 0.41 D 1.27 h 0.18 D 0.25 0 D 8
rev. 1.00 9 may 27, 2011 HT7A3942 reel dimensions sop 8n (150mil) symbol description dimensions in mm a reel outer diameter 330.01.0 b reel inner diameter 100.01.5 c spindle hole diameter 13.0 +0.5/-0.2 d key slit width 2.00.5 t1 space between flange 12.8 +0.3/-0.2 t2 reel thickness 18.20.2
rev. 1.00 10 may 27, 2011 HT7A3942 carrier tape dimensions

sop 8n (150mil) symbol description dimensions in mm w carrier tape width 12.0 +0.3/-0.1 p cavity pitch 8.00.1 e perforation position 1.750.10 f cavity to perforation (width direction) 5.50.1 d perforation diameter 1.550.1 d1 cavity hole diameter 1.50 +0.25/-0.00 p0 perforation pitch 4.00.1 p1 cavity to perforation (length direction) 2.00.1 a0 cavity length 6.40.1 b0 cavity width 5.20.1 k0 cavity depth 2.10.1 t carrier tape thickness 0.300.05 c cover tape width 9.30.1
rev. 1.00 11 may 27, 2011 HT7A3942 holtek semiconductor inc. (headquarters) no.3, creation rd. ii, science park, hsinchu, taiwan tel: 886-3-5631999 fax: 886-3-563-1189 http://www.holtek.com.tw holtek semiconductor inc. (taipei sales offce) 4f-2, no. 3-2, yuanqu st., nankang software park, taipei 115, taiwan tel: 886-2-2655-7070 fax: 886-2-2655-7373 fax: 886-2-2655-7383 (international sales hotline) holtek semiconductor inc. (shenzhen sales offce) 5f, unit a, productivity building, no.5 gaoxin m 2nd road, nanshan district, shenzhen, china 518057 tel: 86-755-8616-9908, 86-755-8616-9308 fax: 86-755-8616-9722 holtek semiconductor (usa), inc. (north america sales offce) 46729 fremont blvd., fremont, ca 94538, usa tel: 1-510-252-9880 fax: 1-510-252-9885 http://www.holtek.com copyright ? 2011 by holtek semiconductor inc. the information appearing in this data sheet is believed to be accurate at the time of publication. however, holtek assumes no responsibility arising from the use of the specifications described. the applications mentioned herein are used solely for the purpose of illustration and holtek makes no warranty or representation that such applications will be suitable without further modifcation, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. holtek's products are not authorized for use as critical components in life support devices or systems. holtek reserves the right to alter its products without prior notifcation. for the most up-to-date information, please visit our web site at http://www. holtek.com.tw .

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