high performance current mode pwm controller ap3842/3/4/5 this datasheet contains new product information. anachip corp. rese rves the rights to modify the product specification without notice. no liability is assumed as a result of the use of this product. no rights under any patent accompany the sale of the product. rev.a3 feb.10, 2004 1/8 ? features ? optimized for off-line and dc to dc converters ? low start-up current ( Q 0.5ma) ? automatic feed forward compensation ? pulse-by-pulse current limiting ? enhanced load response characteristics ? under-voltage lockout (uvlo) with hysteresis ? double pulse suppression ? high current totem pole output ? internally trimmed bandgap reference ? current mode operation to 500khz ? low ro error amplifier ? pin connections pdip-8l, sop-8l 1 2 3 4 comp. v fb v ref 5 6 7 8 i sense r t /c t output ground v i top view ? general description the ap3842/3/4/5 family of control ics provides the necessary features to implement off-line or dc to dc fixed frequency current mode control schemes with a minimal external parts count. internally implemented circuits include under voltage lockout featuring start-up curr ent less than 0.5 ma, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a pwm comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. the output stage, suitable for driving n-channel mosfets, is low in the off-state. differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. the ap3842 and ap3844 have uvlo thresholds of 16v(on) and 10v(off), ideally suited for off-line applications. the corresponding thresholds for the ap3843 and ap3845 are 8.5v and 7.6v. the ap3842 and ap3843 can operate to duty cycles approaching 100%. a range of the zero to < 50% is obtained by the ap3844 and ap3845 by the addition of an internal toggle flip flop which blanks the output off every other clock cycle. ? ordering information ap 384x x x x package s8:sop-8l n8:pdip-8l packing blank: tube part no. 2:3842 3:3843 4:3844 5:3845 lead free blank : normal l : lead free package a : taping
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 2/8 ? block diagram ( toggle flip flop used only in ap3844 and ap3845 ) s/r 5v ref t s r r 2r 1v current sense comparator pwm latch 8 6 output vref 5v 50ma internal bias vref good logic 2.50v osc. error amp. 2 1 3 4 5 7 vi ground rt/ct vfb comp current sense 16v ap384x uvlo 36v ? absolute maximum ratings symbol parameter value unit v i supply voltage (low impedance source) 36 v v i supply voltage (li < 30ma) self limiting i o output current 0.7 a e o output energy (capacitive load) 5 j analog inputs (pins2,3) -0.3 to 5.5 v error amplifier output sink current 10 ma p tot power dissipation at t amb Q 50 0 c (pdip8) 1.25 w p tot power dissipation at t amb Q 25 0 c (sop8) 800 mw t stg storage temperature range -65 to 150 o c t l lead temperature (soldering 10s) 260 o c *notes: 1. all voltages are with respect to pin 5, all currents are positive into the specified terminal. ? electrical characteristics (unless otherwise stated, thes e specifications apply for 0 Q t amb Q 70 o c for ap384x ; v i = 15v(note 5); r t = 10k ? ;c t = 3.3nf) ap384x symbol parameter test conditions min. typ. max. unit reference section v ref output voltage tj = 25 0 c i 0 =1ma 4.90 5.00 5.10 v v ref line regulation 12v Q v i Q 25v 2 20 mv v ref load regulation 1ma Q i o Q 20ma 3 25 mv v ref/ t temperature stability (notes 2) 0.2 0.4 mv/ 0 c total output variation line, load, temperature (notes 2) 4.82 5.18 v e n output noise voltage 10hz Q f Q 10khz tj=25 0 c (notes 2) 50 v long term stability t amb =125 0 c, 1000hrs (notes 2) 5 25 mv i sc output short circuit current -85 -120 ma
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 3/8 ? electrical characteristics(continued) (unless otherwise stated, thes e specifications apply for 0 Q t amb Q 70 o c for ap384x ; v i = 15v(note 5); r t = 10k ? ;c t = 3.3nf) ap384x symbol parameter test conditions min. typ. max. unit oscillator section f s oscillator frequency tj=25 0 c (notes 6, 7) 49 52 55 khz voltage stability 12v Q v i Q 25v 0.2 1 % temperature stability t min Q t amb Q t max (notes 2) 0.5 % v 4 amplitude v pin4 peak to peak 1.6 v discharge current tj=25 0 c v pin4 =2v 7.8 8.3 8.8 ma error amp section v 2 feedback input voltage v pin1 =2.5v 2.42 2.50 2.58 v i b input bias current v fb =5v -0.1 -2 a a vol 0v Q v 0 Q 4v 65 90 db b unity gain bandwidth tj=25 o c 0.7 1 mhz svrr supply voltage rejection ratio 12v Q v i Q 25v 60 70 db i o output sink current v pin2 =2.7v v pin1 =1.1v 2 6 ma i o output source current v pin2 =2.3v v pin1 =5v -0.5 -0.8 ma v out high v pin2 =2.3v; r l =15k to ground 5 7 v v out low v pin2 =2.7v; r l =15k to pin 8 0.8 1.1 v current sense section g v gain (notes3¬es4) 2.85 3 3.15 v/v v 3 maximum input signal v pin1 =5v (notes3) 0.9 1 1.1 v svrr supply voltage rejection ratio 12 Q v i Q 25v (notes3) 70 db i b input bias current -2 -10 a delay to output 150 300 ns output section i sink = 20ma 0.1 0.4 v v ol output low level i sink = 200ma 1.6 2.2 v i source = 20ma 13 13.5 v v oh output high level i source = 200ma 12 13.5 v t r rise time tj=25 0 c c l =1nf (notes2) 50 150 ns t f fall time tj=25 0 c c l =1nf (notes2) 50 150 ns v ols uvlo saturation vcc = 6v ; isink = 1ma 0.1 1.1 v under-voltage lockout section 3842/4 14.5 16 17.5 v start threshold 3843/5 7.8 8.4 9 v 3842/4 8.5 10 11.5 v min operating voltage after turn-on 3843/5 7.0 7.6 8.2 v pwm section 3842/3 94 96 % maximum duty cycle 3844/5 47 48 50 % minimum duty cycle 0 % total standby current i st start-up current vi=14v,3842/4 ; vi=6.5v 3843/5 0.3 0.5 ma i i operating supply current v pin2 =v pin3 =0v 12 17 ma v iz zener voltage i i =25ma 30 36 v
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 4/8 notes 2.these parameters, although guaranteed, are not 100% tested in production. 3.parameter measured at trip point of latch with v pin2 =0. 4.gain defined as: ? v pin1 a= ? v pin3 ; 0 Q v pin3 Q 0.8v 5.adjust v i above the start threshold before setting at 15v. 6.output frequency equals oscillator frequency for the ap3842 and ap3843. 7.output frequency is one and half oscillator frequency for the ap3844 and ap3845. figure 1 : error amp configuration. zf zf comp v fb 2 1 2.5v 0.8 ma error amp can source or sink up to 0.5ma figure 2 : under voltage lockout . ap3842 ap3844 ap3843 ap3845 v on v off 16v 10v 8.4v 7.6v 7 v i on/off command to rest of ic i cc v cc v on v off <1 ma <17 ma during under-voltage lockout, the output driver is bias ed to sink minor amounts of current. pin 6 should be shunted to ground with a bleeder resistor to prevent activating the power switch with extraneous leakage currents. figure 3 : current sense circuit. 3 1 5 r 2r 1v current sense comparator error amp comp current sense gnd c r rs i s
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 5/8 peak current(i s ) is determined by the formula 1.0v i s max r s a small rc filter may be required to suppress switch transients. figure 4 . 5 4 8 r t c t v ref r t /c t ground for r t > 5k f= 1.72 r t c t figure 5 : open loop test circuit. 1 2 3 4 5 6 7 8 comp. v fb v ref i sense r t/ c t output ground v i ap3842 a ground output vi v ref tw 1k 0.1 uf 0.1 uf c t 5k 4.7k 4.7k 1k 100k i sense adjust error amp. adjust r t 2n2222 high peak currents associated with capacitive loads necessitate careful grounding techniques. timing and bypass apacitors should be connected close to pin 5 in a single point ground. the transistor and 5 k potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3. figure 6 : shutdown techniques . 3 b 1 comp shutdown to current sense resistor v ref i sense 1k 500k 330k shutdown
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 6/8 shutdown of the ap3842 can be accomplished in two ways; either raise pin 3 above 1v or pull pin 1 below a voltage two diode drops above ground. either one of them causes the output of the pwm comparator to be high (refer to block diagram). the pwm latch is reset dominant so that the output will remain low until the next clock cycle after the shutdown c ondition at pins 1 and/or 3 is remov ed. in one example, an externally latched shutdown may be accomplished by adding an scr that will be reset by cycling v i below the lower uvlo threshold. at this point the reference turns off, allowing the scr to reset. figure 7 : slope compensation. 8 3 4 uref rt/ct isense ct rt r1 r2 c rsense isense 0.1uf ap3842/3 a fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope compensation for converters requiring dut y cycles over 50%. note that c apacitor, c, forms a filter with r 2 to suppress the leading edge switch spikes.
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 7/8 ? package diagrams (1) pdip-8l (plastic dual-in-line package) e1 d 7 (4x) a l a2 a1 b2 b1 b e s 15 (4x) e c eb e-pin o0.118 inch pin #1 indent o0.025 deep 0.006-0.008 inch dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a - - 5.33 - - 0.210 a1 0.38 - - 0.015 - - a2 3.1 3.30 3.5 0.122 0.130 0.138 b 0.36 0.46 0.56 0.014 0.018 0.022 b1 1.4 1.52 1.65 0.055 0.060 0.065 b2 0.81 0.99 1.14 0.032 0.039 0.045 c 0.20 0.25 0.36 0.008 0.010 0.014 d 9.02 9.27 9.53 0.355 0.365 0.375 e 7.62 7.94 8.26 0.300 0.313 0.325 e1 6.15 6.35 6.55 0.242 0.250 0.258 e - 2.54 - - 0.100 - l 2.92 3.3 3.81 0.115 0.130 0.150 eb 8.38 8.89 9.40 0.330 0.350 0.370 s 0.71 0.84 0.97 0.028 0.033 0.038
high performance current mode pwm controller ap3842/3/4/5 anachip corp. www. anachip.com.tw rev.a3 feb.10, 2004 8/8 (2) sop-8l (jedec small outline package) view "a" l c view "a" h e a a2 a1 b e d 7 (4x) 0.015x45 7 (4x) y dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a 1.40 1.60 1.75 0.055 0.063 0.069 a1 0.10 - 0.25 0.040 - 0.100 a2 1.30 1.45 1.50 0.051 0.057 0.059 b 0.33 0.41 0.51 0.013 0.016 0.020 c 0.19 0.20 0.25 0.0075 0.008 0.010 d 4.80 5.05 5.30 0.189 0.199 0.209 e 3.70 3.90 4.10 0.146 0.154 0.161 e - 1.27 - - 0.050 - h 5.79 5.99 6.20 0.228 0.236 0.244 l 0.38 0.71 1.27 0.015 0.028 0.050 y - - 0.10 - - 0.004 0 o - 8 o 0 o - 8 o ? marking information ac ap384x b yyww x x 2,3,4,5 year : "01"=2001 "02"=2002 xth week : 01~52 id code: internal logo part no. ~ blank: normal l: lead free package
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