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| KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 1 current mode pwm controller ? description ? features ? applications internally implemented circuits include a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power mosfet. protection circuitry includes built under voltage lockout and current limiting. the KA384X are fixed frequency current mode pwm controller. they are specially designed for off-line and dc to dc converter applications with a minimal external components. ? operating frequency up to 500khz ? switching mode power supplies ? power converters ? under voltage lockout with hysteresis ? low star-up and operating current ? high current totem pole output ? pin description block diagram et-
KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 2 ? ordering information part number operating temperature range package packing ka3842ki sop-8 tape & reel ka3843ki sop-8 tape & reel ka3844ki sop-8 tape & reel ka3845ki -40 o c ~ +85 o c sop-8 tape & reel ka3842ji dip-8 tube ka3843ji dip-8 tube ka3844ji dip-8 tube ka3845ji -40 o c ~ +85 o c dip-8 tube ? absolute maximum ratings symbol parameter value unit v cc supply voltage (low impedance source) 30 v i out output current 1 a v in input voltage (analog input pins 2,3) -0.3 ~ 5.5 v i sink(e.a) error amp output sink current 10 ma p d power dissipation (t a =25 o c) 1.0 w t stg storage temperature range -65 ~ 150 o c t lead lead temperature (soldering 5 sec.) 260 o c ? thermal characteristics symbol parameter package typical value unit sop-8 160 ja thermal resistance from junction to ambient in free air. (measured with the component mounted on a high effective thermal conductivity test board in free air.) dip-8 100 o c/w et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 3 ? electrical characteristics (t a =25 c, v cc =15v, r t =10k ? , c t =3.3nf, t a =0 o c to +70 o c, unless otherwise specified .) symbol parameter test condition min. typ. max. unit reference section v ref reference output voltage t j =25 o c, i ref =1ma 4.9 5.0 5.1 v reg line line regulation 12v v cc 25v - 6.0 20 mv reg load load regulation 1ma i ref 20ma - 6.0 25 mv i sc short circuit output current t a =25 o c - -100 -180 ma oscillator section f oscillator frequency t j =25 o c 47 52 57 khz f/ v cc frequency change with voltage 12v v cc 25v - 0.05 1.0 % v (osc) oscillator amplitude (peak to peak) - 1.6 - v error amplifier section i bias input bias current v fb =3v - -0.1 -2.0 ua v in(e.a) input voltage v pin1 =2.5v 2.42 2.5 2.58 v a vol open loop voltage gain 2v vo 4v 65 90 - db ugbw unity gain bandwidth tj=25 o c, note 3 0.5 0.6 - mhz psrr power supply rejection ratio 12v v cc 25v 60 70 - db i sink output sink current v pin2 =2.7v, v pin1 =1.1v 2.0 7.0 - ma i source output source current v pin2 =2.3v, v pin1 =5.0v -0.5 -1.0 - ma v oh high output voltage v pin2 =2.3v, r l =15k ? to gnd 5.0 6.0 - v v ol low output voltage v pin2 =2.3v, r l =15k ? to pin 8 - 0.8 1.1 v current sense section g v gain ( note 1 & 2 ) 2.85 3.0 3.15 v/v v in(max) maximum input signal v pin1 =5v (note 1) 0.9 1.0 1.1 v svr supply voltage 12v v cc 25v - 70 - db i bias input bias current v pin3 =3v - -3.0 -10 ua output section i sink =20ma - 0.08 0.4 v ol low output voltage i sink =200ma - 1.4 2.2 i sink =20ma 13 13.5 v oh high output voltage i sink =200ma 12 13.0 - v t r rise time t j =25 o c,c l =1nf (note 3) - 45 150 t f fall time t j =25 o c,c l =1nf (note 3) - 35 150 ns under-voltage lockout section ka3842 / ka3844 14.5 16.0 17.5 v th(st) start threshold ka3843 / ka3845 7.8 8.4 9.0 v ka3842 / ka3844 8.5 10 11.5 v opr(min) min. operating voltage (after turn on) ka3843 / ka3845 7.0 7.6 8.2 v et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 4 ? electrical characteristics (con.) (t a =25 c, v cc =15v, r t =10k ? , c t =3.3nf, t a =0 o c to +70 o c, unless otherwise specified .) symbol parameter test condition min. typ. max. unit pwm section ka3842 / ka3843 95 97 100 d (max.) max. duty cycle ka3844 / ka3845 47 48 50 d (min.) min. duty cycle - - 0 % total standby current ka3843 / ka3845 - 0.13 0.3 i st start-up current ka3842 / ka3844 - 0.2 0.3 i cc(opr) operating supply current v pin3 =v pin2 =0v - 13 17 ma v z zener voltage i cc =25ma 30 38 - v * adjust v cc above the start threshold before setting it to 15v. notes: note 1: parameter measur ed 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. ? pin function pin function description 1 comp this pin is the error amplifier output and is made for loop compensation. 2 v fb this is the inverting input of the error amplifier. it is normally connected to the switching power supply output through a resistor divider. 3 i sense a voltage proportional to inductor current is connected to this input. the pwm uses this information to terminate the output switch conduction. 4 r t /c t the oscillator frequency and maximum output duty cycle are programmed by connecting resistor r t to v ref and capacitor c t to ground. 5 gnd this pin is the combined control circuitry and power ground. 6 out this output directly drivers the gate of a powe r mosfet. peak currents up to 1a are soured and sink by this pin. 7 v cc this pin is the positive supp ly of the integrated circuit. 8 v ref this is the reference output. it provid es charging current for capacitor c t through resistor r t . et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 5 ? application information ka3842 ka3844 16v ka3843 ka3845 8.4v v on 7.6v 10v v off et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 6 ? application information (con.) et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 7 ? application information (con.) et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 8 ? application information (con.) et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 9 ? typical characteristics (ka384 2/43) et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 10 ? typical caracteristics (con.) et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 11 ? package information sop-8 et- KA384X www.estek.com.cn copyright @ estek electronics co., ltd version 0.2 27 july 2011 12 ? package information dip-8 et- |
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