description pin connection (top view) the hy 3842d-n/3843d-n/3844d-n/3845d-n, are fixed frequency current mode pw m controller. t hey are specially designed for of f ? line and dc to dc converter applications w i th a minimal external components. internally implemented circuits include a trimmed oscillator for precise duty cy cle control, a te mperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a pow er mosf et . protection circuitry includes built under voltage lockout and cu rrent limiting. the hy 3842d-n, hy 3844d-n, have uvlo thresholds of 16 v (on) and 10 v (off). the corresponding thresholds for the hy 3843d-n/3845d- n a r e 8.4v (on) and 7.6v (off). t he hy 3842d-n, hy 3843d-n, can operate within 100% duty cycle. the hy 3844d-n, hy 3845d-n, can operate w i thin 50% duty cy cle. the hy 384xd-n have star t-up current 0.17ma (typ). features ? low start-up and operating current ? high current totem pole output ? under voltage lockout w i th hy steresis ? operating f r equency up t o 500khz block diagram (toggle flip flop used only in hy 3844, hy 3845) absolute maximum ratings c h a r a c t e r i s t i c s y m b o l v a l u e u n i t supply voltage (low impedance source) v cc 3 0 v output current i o 1 a input voltage (analog inputs pins 2,3) v i ? 0.3 to 5.5 v error amp output sink current i sink (e.a) 1 0 m a pow e r dissipation (t a =25 0 c ) p o 1 w storage temperature range tstg -65 to150 o c lead temperature (soldering 5 sec.) t l 260 o c HY3842/43/44/45 1 1 www.hooyi-semi.com 1 free datasheet http://www.ndatasheet.com
electrical characteristics (*v cc =15v, r t =10k ? , c t =3.3nf, t a =0 0 c to +70 0 c, unless otherwise specified) characteristics symbol test condition min typ max unit reference section reference output voltage v ref t j = 25 c, i ref = 1 ma 4.9 5.0 5.1 v line regulation ? v ref 12v v cc 25 v 6.0 20 mv load regulation ? v ref 1 ma i ref 20ma 6.0 25 short circuit output current i sc t a = 25 c -100 -180 ma oscillator section oscillation frequency f t j = 25 c 47 52 57 khz frequency change with voltage ? f/ ? v cc 12v v cc 25 v 0.05 1.0 % oscillator amplitude v (osc) (peak to peak) 1.6 v error amplifier section input bias current i bias v fb =3v -0.1 -2 a input voltage v i(e.a) v pin1 = 2.5v 2.42 2.5 2.58 v open loop voltage gain a vol 2v v 0 4v 65 90 db unity gain bandwidth ugbw t j =25 0 c, note 3 0.5 0.6 mhz power supply rejection ratio psrr 12v v cc 25 v 60 70 db output sink current i sink v pin2 = 2.7v, v pin1 = 1.1v 2 7 ma output source current i source v pin2 = 2.3v, v pin1 = 5v -0.5 -1.0 ma high output voltage v oh v pin2 = 2.3v, r l = 15k ? to gnd 5.0 6.0 low output voltage v ol v pin2 = 2.7v, r l = 15k ? to pin 8 0.8 1.1 v current sense section gain g v (note 1 & 2) 2.85 3.0 3.15 v/v maximum input signal v i(max) v pin1 = 5v (note1) 0.9 1.0 1.1 v supply voltage rejection svr 12v v cc 25 v (note 1) 70 db input bias current i bias v pin3 = 3v -3.0 -10 a output section low output voltage v ol i sink = 20 ma 0.08 0.4 i sink = 200 ma 1.4 2.2 high output voltage v oh i sink = 20 ma 13 13.5 i sink = 200 ma 12 13.0 v rise time t r t j = 25 c, c l = 1nf (note 3) 45 150 fall time t f t j = 25 c, c l = 1nf (note 3) 35 150 ns undervoltage lockout section start theshold v th(st) hy 3842d-n/44d-n 14.5 16.0 17.5 hy 3843d-n/45d-n 7.8 8.4 9.0 v min. operating voltage v opr(min) hy 3842d-n/44d-n 8.5 10 11.5 (after turn on) hy 3843d-n/45d-n 7.0 7.6 8.2 v pwm section max. duty cycle d (max) hy 3842d-n/43d-n 95 97 100 hy 3844d-n/45d-n 47 48 50 % min. duty cycle d (max) 0 total standby current hy 3843d-n, hy 3845d-n 0.17 0.3 hy 3842d-n, hy 3844d-n 0.17 0.3 start ? up current i st operating supply current i cc (opr) v pin3 = v pin2 = 0v 13 17 ma zener voltage v z i cc =25 ma 30 38 v * adjust v cc above the start threshold before setting it to 15v. note 1: parameter measured at trip point of latch with v pin2 =0. note 2: gain defined as a= ? v pin1 / ? v pin3 ; 0 v pin3 0.8v. note 3: these parameters, although guaranteed, are not 100% tested in production. HY3842/43/44/45 1 2 www.hooyi-semi.com 2 free datasheet http://www.ndatasheet.com
pin function n f u n c t i o n d e s c r i p t i o n 1 comp t h is pin is the error amplifie r output and is made for loop compensation. 2 v fb t h is is the inverting input of t he error amplifier. it is normally c onnected to the sw itching pow er supply output through a resistor divider. 3 i sen se a voltage proportional to inductor current is connected to this input. t he pw m uses this information to terminate the output sw itch conduction. 4 r t /c t t he oscillator frequency and maximum output duty cy cle are programmed by connecting resistor r t to v re f and capacitor c t to ground. 5 ground t h is pin is the combined control circuitry and pow er ground. 6 out p ut t h is output directly drives the gate of a pow er mosf et . peak cu rrents up to 1a are sourced and sink by this pin. 7 v cc t h is pin is the positive suppl y of the integrated circuit. 8 v re f t h is is the reference output. it provi des charging current for capacitor c t through resistor r t . application information f i gure 1. error amp configuration f i gure 2. under voltage lockout HY3842/43/44/45 HY3842 hy3845 hy3844 hy3843 3 3 free datasheet http://www.ndatasheet.com
figure 3. current sense circuit f i gure 4. slope compensation t e chniques HY3842/43/44/45 HY3842 HY3842 4 www.hooyi-semi.com 4 free datasheet http://www.ndatasheet.com
scr must be selected for a holding current of less than 0.5ma. the simple tw o transistor circuit can be used in place of the scr as show n. f i gure 5. latched shutdow n f i gure 6. error amplifier compensation HY3842/43/44/45 hooyi-semi.com 5 www.hooyi-semi.com 5 free datasheet http://www.ndatasheet.com
figure 7. ex ternal clock sy nchronization figure 8. soft-start circuit HY3842/43/44/45 6 www.hooyi-semi.com 6 free datasheet http://www.ndatasheet.com
typical performance characteristics figure 1. t i ming resistor vs. oscillator frequency figure 2. output dead-t i me vs. oscillator frequency f i gure 3. maximum output duty cy cle vs. f i gure 4. error amp open-loop gain vs. t iming resistor ( hy 3842/43) frequen cy figure 5. current sense input threshold vs. figure 6. reference short circuit current vs. error amp output voltage temperature HY3842/43/44/45 7 www.hooyi-semi.com 7 free datasheet http://www.ndatasheet.com
www.hooyi-semi.com f i gure 7. output saturation voltage vs. load current f i gure 8. supply current vs. supply voltage t a = 2 5 c figure 9. oscillator and output w a veforms HY3842/43/44/45 8 8 free datasheet http://www.ndatasheet.com
pad location 5 7 7 8 6 5 4 1 2 3 chip size: 1.82 x 1.35 mm 2 pad location coordinates coordina te s m pad n pad name x y 1 c o m p 1 1 4 1 1 5 2 v fb 8 6 1 1 1 5 3 i sen se 1 0 7 7 1 1 5 4 r t /c t 1 5 4 5 1 4 3 5 p o w e r g n d 1 4 8 7 1 0 9 0 5 g n d 1 4 5 9 1 2 4 0 6 o u t 1 1 6 7 1 2 0 7 7 p o w e r v cc 8 7 3 1 2 0 7 7 v cc 7 2 3 1 2 0 7 8 v re f 4 5 3 1 2 0 7 t he appearance complies w i th the requi rements of the company standards. HY3842/43/44/45 9 www.hooyi-semi.com 10 free datasheet http://www.ndatasheet.com
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