?2005 fairchild semiconductor corporation www.fairchildsemi.com rev. 1.0.1 features ? low start current 0.2ma (typ) ? operating range up to 500khz ? cycle by cycle current limiting ? under voltage lock out with hysteresis ? short shutdown delay time: typ.100ns ? high current totem-pole output ? output swing limiting: 22v description the ka3843ac are fixed pwm controller for off-line and dc to dc converter applications. the internal circuits include uvlo, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a power mosfet. also ka3843ac provide low start up current below 0.3ma and short shutdown delay time typ. 100ns. the ka3843ac is 8.4v(on) and 7.6v(off). the ka3843ac can operate within 100% duty cycle. 8-dip 8-sop 1 1 internal block diagram 8 + - 7 5 set/ reset 5v v ref internal bias good logic 2 r s oscillator 1 3 4 t 7 6 5 uvlo 29v 22v 1/3 error amp 1/2v ref 1v c.s comp. pwm latch v ref v fb comp c.s r t /c t output v cc gnd pwr v c pwr gnd ka3843ac smps controller
ka3843ac 2 absolute maximum ratings electrical characteristics (v cc = 15v, r t = 10kw, c t = 3.3nf, t a = 0 c to +70 c ,unless otherwise specified) notes: 1. these parameters, although guaranteed, are not 100% tested in production. 2. parameter measured at trip point of latch with v fb = 0v. 3. gain defined as: parameter symbol value unit supply voltage v cc 30 v output current i o +1 a analog inputs (pin2, 3) v i(ana) -0.3 to 6.3 v error amp. output sink current i sink(ea) 10 ma power dissipation p d 1w parameter symbol conditions min. typ. max. unit reference section output voltage v ref t j = 25 c, i o = 1ma 4.9 5.0 5.1 v line regulation r line v cc = 12v to 25v - 6 20 mv load regulation r load i o = 1ma to 20ma - 6 25 mv output short circuit i sc t a = 25 c - -100 -180 ma osillator section initial accuracy f osc t j = 25 c475257khz voltage stability st v v cc = 12v to 25v - 0.2 1 % amplitude v osc v pin4 , peak to peak - 1.7 - v discharge current i dischg t j = 25 c 7.8 8.3 8.8 ma current sense section gain g v (note2, 3) 2.85 3 3.15 v/v maximum input signal v i(max) v pin1 = 5v(note2) 0.9 1.0 1.1 v psrr psrr v cc = 12v to 25v (note1, 2) - 70 - db input bias current i bias v sense =0v - -2 -10 ua delay to output t d v pin3 = 0 v to 2v (note1) - 100 200 ns g v ? v comp ? v sense ------------------------- ov sense 0.8v ? ; =
ka3843ac 3 electrical characteristics (continued) (v cc = 15v, r t = 10kw, c t = 3.3nf, t a = 0 c to +70 c, unless otherwise specified) * adjust v cc above the start threshold before setting at 15v notes : 1. these parameters, although guaranteed, are not 100% tested in production. 2. parameter measured at trip point of latch with v fb = 0v. 3. gain defined as: parameter symbol conditions min. typ. max. unit error amplifier section input voltage v i v pin1 = 2.5v 2.42 2.50 2.58 v input bias current i bias v fb =0v - -0.3 - 2 ua open loop gain g vo v o = 2v to 4v (note1) 65 90 - db unity gain bandwidth gbw t j = 25 c (note1) 0.7 1 - mhz psrr psrr v cc = 12v to 25v (note1) 60 70 - db output sink current i sink v pin2 = 2.7v, v pin1 = 1.1v 2 6 - ma output source current i source v pin2 = 2.3v, v pin1 = 5.0v -0.5 -0.8 - ma output high voltage v oh v pin2 = 2.3v r1 = 15k ? to gnd 56 -v output low voltage v ol v pin2 = 2.7v r1 = 15k ? to vref -0.71.1v output section output low level v ol i sink = 20ma - 0.1 0.4 v i sink = 200ma - 1.5 2.2 v output high level v oh i source = 20ma 13 13.5 - v i source = 200ma 12 13.5 - v rise time t r t j = 25 c, c1 = 1nf (note1) - 40 100 ns fall time t f t j = 25 c, c1 = 1nf (note1) - 40 100 ns output voltage swing limit v olim v cc = 27v, c1 = 1nf - 22 - v under voltage lockout section start threshold v th ka3882e 15 16 17 v ka3883e 7.8 8.4 9.0 v min. operating voltage ( after turn on ) v tl ka3882e 9 10 11 v ka3883e 7.0 7.6 8.2 v pwm section maximum duty cycle d max ka3882e/ka3883e 94 96 100 % minimum duty cycle d min ---0% total standby current start-up current i st --0.20.4ma operating supply current i cc v pin2 = v pin3 = 0v - 11 17 ma v cc zener voltage v z i cc = 25ma - 29 - v g v ? v comp ? v sense ------------------------- ov sense 0.8v ? ; =
ka3843ac 4 mechanical dimensions package dimensions in millimeters 6.40 0.20 3.30 0.30 0.130 0.012 3.40 0.20 0.134 0.008 #1 #4 #5 #8 0.252 0.008 9.20 0.20 0.79 2.54 0.100 0.031 () 0.46 0.10 0.018 0.004 0.060 0.004 1.524 0.10 0.362 0.008 9.60 0.378 max 5.08 0.200 0.33 0.013 7.62 0~15 0.300 max min 0.25 +0.10 ?.05 0.010 +0.004 ?.002 8-dip
ka3843ac 5 mechanical dimensions (continued) package dimensions in millimeters 8-sop
ka3843ac 3/2/05 0.0m 001 stock#dsxxxxxxxx ? 2005 fairchild semiconductor corporation life support policy fairchild?s products are not authorized for use as critical components in life support devices or systems without the express written approval of the president of fairchild semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. a critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com disclaimer fairchild semiconductor reserves the right to make changes without further notice to any products herein to improve reliability, function or design. fairchild does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. ordering information product number package operating temperature ka3843ac 8-dip 0 ~ +70 c ka3843acd 8-sop
careers | sitema go datasheets, samples, buy technical information applications design center support company investors my f a home >> find products >> product status/pricing/packaging ka3843a smps controller general description back to top features back to top contents ? general description ? features ? product status/pricing/packaging ? order samples ? qualification support the ka3843ac are fixed pwm controller for off-line and dc to dc converter applications. the internal circuits include uvlo, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a power mosfet. also ka3843ac provide low start up current below 0.3ma and short shutdown delay time typ. 100ns. the ka3843ac is 8.4v(on) and 7.6v(off). the ka3843ac can operate within 100% duty cycle. z low start current 0.2ma (typ) z operating range up to 500khz z cycle by cycle current limiting z under voltage lock out with hysteresis z short shutdown delay time: typ.100ns z high current totem-pole output z output swing limiting: 22v datasheet download this datasheet e - mail this datasheet this page print version product product status pb-free status pricing* package type leads packing method related links request samples how to order products product change notices (pcns) support sales support quality and reliability design cente r pa g e 1 of 2 product folder - fairchild p/n ka3843a - smps controlle r 17-au g -2007 mhtml:file://c:\ temp\KA3843ACS.mht
back to top qualification support click on a product for detailed qualification data back to top KA3843ACS full production $0.445 dip 8 rail * fairchild 1,000 piece budgetary pricing ** a sample button will appear if the part is available through fa irchild's on-line samples program. if there is no sample butt on, please contact a fairchild distributor to obtain samples indicates product with pb -free second-level interconne ct. for more information click here. product KA3843ACS ? 2007 fairchild semiconductor products | design center | support | company news | investors | my fairchild | contact us | site index | privacy policy | site terms & conditions | standard terms & conditions o pa g e 2 of 2 product folder - fairchild p/n ka3843a - smps controlle r 17-au g -2007 mhtml:file://c:\ temp\KA3843ACS.mht
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