? semiconductor components industries, llc, 2006 july, 2006 ? rev. 4 1 publication order number: cs2842a/d cs2842a, CS3842A, cs2843a, cs3843a off?line current mode pwm control circuit with undervoltage lockout the cs284xa, cs384xa provides all the necessary features to implement off ? line fixed frequency current ? mode control with a minimum number of external components. the cs384xa family incorporates a new precision temperature ? controlled oscillator with an internally trimmed discharge current to minimize variations in frequency. a precision duty ? cycle clamp eliminates the need for an external oscillator when a 50% duty ? cycle is used. duty ? cycles greater than 50% are also possible. on board logic ensures that v ref is stabilized before the output stage is enabled. ion implant resistors provide tighter control of undervoltage lockout. other features include low startup current, pulse ? by ? pulse current limiting, and a high ? current totem pole output for driving capacitive loads, such as the gate of power mosfet. the output is low in the off state, consistent with n ? channel devices. the cs384xa series of current ? mode control ics are available in 8 and14 lead packages for surface mount (so) applications as well as 8 lead pdip packages. features ? optimized for off ? line control ? internally trimmed temperature compensated oscillator ? maximum duty ? cycle clamp ? v ref stabilized before output stage is enabled ? low startup current ? pulse ? by ? pulse current limiting ? improved undervoltage lockout ? double pulse suppression ? 1.0% trimmed bandgap reference ? high current totem pole output http://onsemi.com x = 2 or 3 y = 2 or 3 a = assembly location wl, l = wafer lot yy, y = year ww, w = work week dip ? 8 n suffix case 626 1 8 so ? 8 d suffix case 751 1 8 so ? 14 d suffix case 751a 1 14 1 8 x84ya awl yyww marking diagram 1 x84ya alywx 8 1 csx84ya awlyww 14 see detailed ordering and shipping information in the package dimensions section on page 8 of this data sheet. ordering information
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 2 pin connections gnd osc v out sense v cc v fb v ref comp 1 gnd osc pwr gnd nc v out sense v cc pwr nc 114 v cc v fb nc nc v ref comp 8 dip ? 8 & so ? 8so ? 14 figure 1. block diagram set/ reset 5.0 v reference undervoltage lock ? out circuit 16 v/10 v (8.4 v/7.6 v) 34 v v cc gnd output enable internal bias oscillator osc 2.50 v v cc pwr v ref v out + ? v fb comp error amplifier s r v c 2r r 1.0 v sense current sensing comparator pwm latch pwr gnd ( ) indicates cs2843a/3843a nor
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 3 maximum ratings* rating value unit supply voltage (i cc < 30 ma) self limiting ? supply voltage (low impedance source) 30 v output current 1.0 a output energy (capacitive load) 5.0 j analog inputs (v fb , sense) ? 0.3 to + 5.5 v error amp output sink current 10 ma package thermal resistance, pdip ? 8 junction ? to ? case, r jc junction ? to ? ambient, r ja 52 100 cw cw package thermal resistance, so ? 8 junction ? to ? case, r jc junction ? to ? ambient, r ja 45 165 cw cw package thermal resistance, so ? 14 junction ? to ? case, r jc junction ? to ? ambient, r ja 30 125 cw cw lead temperature soldering: wave solder (through hole styles only) (note 1) reflow (smd styles only) (note 2) 260 peak 230 peak c c 1. 10 second maximum. 2. 60 second maximum above 183 c. *the maximum package power dissipation must be observed. electrical characteristics ( ? 25 t a 85 for cs2842a/cs2843a, 0 t a 70 for CS3842A/cs3843a. v cc = 15 v*; r t = 680 , c t = 0.022 f for triangular mode, r t = 10 k , c t = 3.3 nf for sawtooth mode (see figure 7); unless otherwise stated.) characteristic test conditions cs2842a/cs2843a CS3842A/cs3843a unit min typ max min typ max reference section output voltage t j = 25 c, i out = 1.0 ma 4.95 5.00 5.05 4.90 5.00 5.10 v line regulation 12 v in 25 v ? 6.0 20 ? 6.0 20 mv load regulation 1.0 i out 20 ma ? 6.0 25 ? 6.0 25 mv temperature stability note 3. ? 0.2 0.4 ? 0.2 0.4 mv/ c total output variation line, load, temperature (note 3.) 4.90 ? 5.10 4.82 ? 5.18 v output noise voltage 10 hz f 10 khz, t j = 25 c (note 3.) ? 50 ? ? 50 ? v long term stability t a = 125 c, 1.0 khrs. (note 3.) ? 5.0 25 ? 5.0 25 mv output short circuit t a = 25 c ? 30 ? 100 ? 180 ? 30 ? 100 ? 180 ma oscillator section initial accuracy sawtooth mode (see figure 7), t j = 25 c triangular mode (see figure 7), t j = 25 c 47 47 52 52 57 57 47 44 52 52 57 60 khz khz voltage stability 12 v cc 25 v ? 0.2 1.0 ? 0.2 1.0 % temperature stability sawtooth mode t min t a t max (note 3.) triangular mode t min t a t max (note 3.) ? ? 5.0 8.0 ? ? ? ? 5.0 8.0 ? ? % % amplitude osc peak to peak ? 1.7 ? ? 1.7 ? v discharge current t j = 25 c t min t a t max 7.5 7.2 8.3 ? 9.3 9.5 7.5 7.2 8.3 ? 9.3 9.5 ma ma 3. these parameters, although guaranteed, are not 100% tested in production. *adjust v cc above the start threshold before setting at 15 v.
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 4 electrical characteristics (continued) ( ? 25 t a 85 for cs2842a/cs2843a, 0 t a 70 for CS3842A/cs3843a. v cc = 15 v*; r t = 680 , c t = 0.022 f for triangular mode, r t = 10 k , c t = 3.3 nf for sawtooth mode (see figure 7); unless otherwise stated.) characteristic test conditions cs2842a/cs2843a CS3842A/cs3843a unit min typ max min typ max error amp section input voltage v comp = 2.5 v 2.45 2.50 2.55 2.42 2.50 2.58 v input bias current v fb = 0 ? ? 0.3 ? 1.0 ? ? 0.3 ? 2.0 a a vol 2.0 v out 4.0 v 65 90 ? 65 90 ? db unity gain bandwidth note 4. 0.7 1.0 ? 0.7 1.0 ? mhz psrr 12 v cc 25 v 60 70 ? 60 70 ? db output sink current v fb = 2.7 v, v comp = 1.1 v 2.0 6.0 ? 2.0 6.0 ? ma output source current v fb = 2.3 v, v comp = 5.0 v ? 0.5 ? 0.8 ? ? 0.5 ? 0.8 ? ma v out high v fb = 2.3 v, 15 k to ground 5.0 6.0 ? 5.0 6.0 ? v v out low v fb = 2.7 v, 15 k to v ref ? 0.7 1.1 ? 0.7 1.1 v current sense section gain notes 5 & 6. 2.85 3.00 3.15 2.85 3.00 3.15 v/v maximum input signal v comp = 5.0 v (note 5.) 0.9 1.0 1.1 0.9 1.0 1.1 v psrr 12 v cc 25 v (note 5.) ? 70 ? ? 70 ? db input bias current v sense = 0 ? ? 2.0 ? 10 ? ? 2.0 ? 10 a delay to output t j = 25 c (note 4.) ? 150 300 ? 150 300 ns output section output low level i sink = 20 ma i sink = 200 ma ? ? 0.1 1.5 0.4 2.2 ? ? 0.1 1.5 0.4 2.2 v v output high level i source = 20 ma i source = 200 ma 13 12 13.5 13.5 ? ? 13 12 13.5 13.5 ? ? v v rise time t j = 25 c, c l = 1.0 nf (note 4.) ? 50 150 ? 50 150 ns fall time t j = 25 c, c l = 1.0 nf (note 4.) ? 50 150 ? 50 150 ns output leakage uvlo active, v out = 0 ? ? 0.01 ? 10.00 ? ? 0.01 ? 10.00 a total standby current startup current ? ? 0.5 1.0 ? 0.5 1.0 ma operating supply current v fb = v sense = 0 v, r t = 10 k , c t = 3.3 nf 11 17 ? 11 17 ? ma v cc zener voltage i cc = 25 ma ? 34 ? ? 34 ? v 4. these parameters, although guaranteed, are not 100% tested in production. 5. parameters measured at trip point of latch with v fb = 0. 6. gain defined as: a = v comp / v sense ; 0 v sense 0.8 v. *adjust v cc above the start threshold before setting at 15 v.
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 5 electrical characteristics (continued) ( ? 25 t a 85 for cs2842a/cs2843a, 0 t a 70 for CS3842A/cs3843a. v cc = 15 v*; r t = 680 , c t = 0.022 f for triangular mode, r t = 10 k , c t = 3.3 nf for sawtooth mode (see figure 7); unless otherwise stated.) characteristic test conditions cs2842a CS3842A cs2843a/cs3843a unit min typ max min typ max min typ max undervoltage lockout section start threshold ? 15 16 17 14.5 16 17.5 7.8 8.4 9.0 v min. operating voltage after turn on 9.0 10 11 8.5 10 11.5 7.0 7.6 8.2 v *adjust v cc above the start threshold before setting at 15 v. package pin description package pin number symbol description dip ? 8 so ? 8 so ? 14 1 ? 9 ? 11 ? 2, 4, 6, 13 typical performance characteristics figure 2. oscillator frequency vs. c t figure 3. oscillator duty cycle vs. r t 900 800 700 600 500 frequency (khz) .0005 .001 .002 .04 .05 c t ( f) 400 300 200 100 .03 .02 .01 .003 .005 r t = 680 r t = 1.5 k r t = 10 k 100 90 80 70 50 duty cycle (%) r t ( ) 40 30 20 10 60 100 200 300 400 500 700 1 k 2 k 3 k 4 k 5 k 7 k 10 k
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 6 figure 4. test circuit v ref v cc v out gnd comp v fb sense osc 0.1 f 0.1 f r t 1.0 k 1.0 w 2n2222 100 k v cc v ref v out gnd a 5.0 k sense adjust c t 4.7 k 4.7 k 1.0 k error amp adjust circuit description csx843a 8.4 v 7.6 v csx842a 16 v 10 v v on v off on/off command to reset of ic v cc < 1.0 ma < 15 ma v on v off v cc i cc figure 5. typical undervoltage characteristics undervoltage lockout during undervoltage lockout (figure 5), the output driver is biased to a high impedance state. the output should be shunted to ground with a resistor to prevent output leakage current from activating the power switch. pwm waveform to generate the pwm waveform, the control voltage from the error amplifier is compared to a current sense signal which represents the peak output inductor current (figure 6). an increase in v cc causes the inductor current slope to increase, thus reducing the duty cycle. this is an inherent feed ? forward characteristic of current mode control, since the control voltage does not have to change during changes of input supply voltage. figure 6. timing diagram for key cs2841b parameters switch current ea output v cc i o v o osc reset osc when the power supply sees a sudden lar ge output current increase, the control voltage will increase allowing the duty cycle to momentarily increase. since the duty cycle tends to exceed the maximum allowed to prevent transformer saturation in some power supplies, the internal oscillator waveform provides the maximum duty cycle clamp as programmed by the selection of oscillator components. setting the oscillator oscillator timing capacitor, c t , is charged by v ref through r t and discharged by an internal current source. during the discharge time, the internal clock signal blanks out the output to the low state, thus providing a user selected maximum duty cycle clamp. charge and discharge times are determined by the formula:
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 7 t c r t c t ln v ref v lower v ref v upper t d r t c t ln v ref i d r t v lower v ref i d r t v upper substituting in typical values for the parameters in the above formulas: v ref = 5.0 v v upper = 2.7 v v lower = 1.0 v i d = 8.3 ma t c 0.5534r t c t t d r t c t ln 2.3 0.0083r t 4.0 0.0083r t the frequency and maximum duty cycle can be determined using the typical performance characteristic graphs. grounding high peak currents associated with capacitive loads necessitate careful grounding techniques. timing and bypass capacitors should be connected close to gnd pin in a single point ground. the transistor and 5.0 k potentiometer, shown in the test circuit, are used to sample the oscillator waveform and apply and adjustable ramp to sense. figure 7. oscillator timing network and parameters internal clock triangular mode v osc v osc internal clock small r t ( 700 k ) large r t ( 10 k ) sawtooth mode timing parameters v upper v lower t c t d v ref osc gnd r t c t
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 8 ordering information device temperature range package shipping cs2842aln8 ? 25 c to 85 c dip ? 8 50 units/rail cs2843aln8 dip ? 8 50 units/rail cs2842ald14 so ? 14 55 units/rail cs2842aldr14 so ? 14 2500 tape & reel CS3842Agn8 0 c to 70 c dip ? 8 50 units/rail CS3842Agd8 so ? 8 98 units/rail CS3842Agdr8 so ? 8 2500 tape & reel CS3842Agd14 so ? 14 55 units/rail CS3842Agdr14 so ? 14 2500 tape & reel cs3843agn8 dip ? 8 50 units/rail cs3843agd8 so ? 8 98 units/rail cs3843agdr8 so ? 8 2500 tape & reel cs3843agd14 so ? 14 55 units/rail cs3843agdr14 so ? 14 2500 tape & reel
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 9 package dimensions dip ? 8 n suffix case 626 ? 05 issue l notes: 1. dimension l to center of lead when formed parallel. 2. package contour optional (round or square corners). 3. dimensioning and tolerancing per ansi y14.5m, 1982. 14 5 8 f note 2 ? a ? ? b ? ? t ? seating plane h j g d k n c l m m a m 0.13 (0.005) b m t dim min max min max inches millimeters a 9.40 10.16 0.370 0.400 b 6.10 6.60 0.240 0.260 c 3.94 4.45 0.155 0.175 d 0.38 0.51 0.015 0.020 f 1.02 1.78 0.040 0.070 g 2.54 bsc 0.100 bsc h 0.76 1.27 0.030 0.050 j 0.20 0.30 0.008 0.012 k 2.92 3.43 0.115 0.135 l 7.62 bsc 0.300 bsc m ??? 10 ??? 10 n 0.76 1.01 0.030 0.040 so ? 8 d suffix case 751 ? 07 issue w seating plane 1 4 5 8 n j x 45 k notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimension a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006) per side. 5. dimension d does not include dambar protrusion. allowable dambar protrusion shall be 0.127 (0.005) total in excess of the d dimension at maximum material condition. a b s d h c 0.10 (0.004) dim a min max min max inches 4.80 5.00 0.189 0.197 millimeters b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.053 0.069 d 0.33 0.51 0.013 0.020 g 1.27 bsc 0.050 bsc h 0.10 0.25 0.004 0.010 j 0.19 0.25 0.007 0.010 k 0.40 1.27 0.016 0.050 m 0 8 0 8 n 0.25 0.50 0.010 0.020 s 5.80 6.20 0.228 0.244 ? x ? ? y ? g m y m 0.25 (0.010) ? z ? y m 0.25 (0.010) z s x s m
cs2842a, CS3842A, cs2843a, cs3843a http://onsemi.com 10 package dimensions so ? 14 d suffix case 751a ? 03 issue f notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. dimensions a and b do not include mold protrusion. 4. maximum mold protrusion 0.15 (0.006) per side. 5. dimension d does not include dambar protrusion. allowable dambar protrusion shall be 0.127 (0.005) total in excess of the d dimension at maximum material condition. ? a ? ? b ? g p 7 pl 14 8 7 1 m 0.25 (0.010) b m s b m 0.25 (0.010) a s t ? t ? f r x 45 seating plane d 14 pl k c j m dim min max min max inches millimeters a 8.55 8.75 0.337 0.344 b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.054 0.068 d 0.35 0.49 0.014 0.019 f 0.40 1.25 0.016 0.049 g 1.27 bsc 0.050 bsc j 0.19 0.25 0.008 0.009 k 0.10 0.25 0.004 0.009 m 0 7 0 7 p 5.80 6.20 0.228 0.244 r 0.25 0.50 0.010 0.019 on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including wi thout limitation special, consequential or incidental damages. ?typical? parameters which may be provided in scillc data sheets and/or specifications can and do vary in different application s and actual performance may vary over time. all operating parameters, including ?typicals? must be validated for each customer application by customer?s technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indemnify and hold scillc and its of ficers, employees, subsidiaries, af filiates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. publication ordering information n. american technical support : 800 ? 282 ? 9855 toll free usa/canada europe, middle east and africa technical support: phone: 421 33 790 2910 japan customer focus center phone: 81 ? 3 ? 5773 ? 3850 cs2842a/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 303 ? 675 ? 2175 or 800 ? 344 ? 3860 toll free usa/canada fax : 303 ? 675 ? 2176 or 800 ? 344 ? 3867 toll free usa/canada email : orderlit@onsemi.com on semiconductor website : www.onsemi.com order literature : http://www.onsemi.com/orderlit for additional information, please contact your local sales representative
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