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LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx general description features 1.5v, 1.8v, 2.5v, 3.3v, 5v, 12v, 15v and adjustable output versions adjustable version output voltage range, 1.23v to 37v 4% max over line and load conditions guaranteed 3a output current w i de input voltage range, 40v requires only 4 external components 52 khz fixed frequency oscillator t t l shutdow n capability , low pow er standby mode high efficiency uses readily available standard inductors t hermal shutdow n and curr ent limit protection applications simple high-efficiency step-dow n (buck) regulator efficient pre-regulator for linear regulators on-card sw itching regulators t he LM2576, LM2576m series of regulators are monolithic integrated circuits t hat provide all the active functions for a step-dow n (buck) sw itching regul ator, capable of driving 3a load w i th excellent line and load regulation. t hese devices are available in fixed output voltages of 3.3v, 5v, 12v, 15v (1.5v, 1.8v, 2.5v the LM2576m only ) and adjustable output versions. requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fi xed-frequency oscillator. t he LM2576, LM2576m series offers a high-efficiency replacement for popular three- terminal linear regulators. it substantially reduces the size of the heat sink, and in some cases no heat sink is required. a standard series of inductors optimized for use w i th the LM2576, LM2576m are available from several different manufacturers. t h is feature gr eatly simplifies the design of sw itch-mode pow er supplies. other features include a guaranteed 4% tolerance on output voltage w i thin specifi ed input voltages and output load conditions, and 10% on the oscillator frequency . external shutdow n is incl uded, featuring 50 a (ty p ical) standby current. t he output sw itch includes cy cle- by -cy c le current limiting, as w e ll as thermal shutdow n fo r full protection under fault conditions. positive to negative converter (buck-boost) typical application (fixed output voltage versions) figure 1. f + +5v regulated outp ut 3a load LM2576 LM2576m LM2576mk +v in 1 c in 3 gnd on/off output 4 l1 100 h d1 1n5822 c out 10 0 0 100 f 2 + 5 unregulat e LM2576m1k feedback 7v - 40v ( 6 0 v f o r h v ) unregulated dc input unregulated dc input - 1 - silicon link inc. june 2007 rev. 0
block diagram 1.5v, r2= 220 ? 1.8v, r2= 467 ? 2.5v, r2= 1 .036 ? + c in c ou t feed - back + 1 4 + - - + dr i ver 1. 2 3 v band-g a p reference 52 kh z osci ll at or reset thermal shutdo wn current li m i t 3 2 l1 l o a d internal regu l a tor on / o f f 5 r2 r1 1. 0 k fixed gain e r ror am p co m parator 3 a m p swi t c h out p ut gnd v ou t d1 on/ o f f v in unregu l a ted dc input 3.3v, r2 =1.7k 5v, r2 = 3.1k 12v, r2 = 8.84k 15v, r2 = 11.3k for adj, version r1 = open, r2 = 0 ? ordering information output voltage t e mp eratu r e ra nge 1 . 5 1 . 8 2 . 5 3 . 3 5 . 0 1 2 1 5 ad j l m 2 5 7 6 -3.3 LM2576 -5.0 LM2576 -12 LM2576 -15 LM2576 -adj LM2576m -1.5 LM2576m -1.8 LM2576m -2.5 LM2576m -3.3 LM2576m -5.0 LM2576m -12 LM2576m -15 LM2576m -adj LM2576mk -1.5 LM2576mk -1.8 LM2576mk -2.5 LM2576mk -3.3 LM2576mk -5.0 LM2576mk -12 LM2576mk -15 LM2576mk -adj -40 c t a 125 c LM2576m1k -1.5 LM2576m1k -1.8 LM2576m1k -2.5 LM2576m1k -3.3 LM2576m1k -5.0 LM2576m1k -12 LM2576m1k -15 LM2576m1k -adj LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx marking information & pin configurations (top view) v v, vvv = output voltage (33 = 3.3v, 120= 12v, a =a dj ) a = assembly location y =year w w =weekly 1 2 3 4 8 7 6 5 gnd gnd vin vout on/off fb LM2576 vvayww gnd gnd - 2- silicon link inc. june 2007 rev. 0 sop- 8fd
minimum esd rating: LM2576, LM2576m, LM2576mk 1kv l m 2 5 7 6 m 1 k 2 k v absolute maximum ratings (note 1) (c= 100pf , r = 1.5 k ? ) lead t e mperature (soldering, 10 seconds) 260 c maximum supply voltage operating ratings LM2576, LM2576m, LM2576mk, LM2576m1k 45v t e mperature range _ on/of f pin input voltage -0.3v v +v in LM2576, LM2576m, LM2576mk, LM2576m1k -40 c t j + 125 c output voltage to ground supply voltage (steady state) -1v pow e r dissipation internally limited LM2576, LM2576m, LM2576mk, LM2576m1k 40v storage t e mperature range -65 c to +150 c maximum junction t e mperature 150 c LM2576m-1.5, LM2576mk-1.5, LM2576m1k-1.5 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (no t e 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 12v, i load =0.5a circuit of f i gure 2 1.5 1.470 1.530 v v(min) v(max ) v out output voltage 4.2v v in 40v, 0.5a i load 3a circuit of f i gure 2 1.5 1.440/ 1.425 1.560/ 1.575 v v(min) v(max ) LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 3 - silicon link inc. june 2007 rev. 0
LM2576m-1.8, LM2576mk-1.8, LM2576m1k-1.8 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (note 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 12v, i load =0.5a circuit of f i gure 2 1.8 1.764 1.836 v v(min) v(max ) v out output voltage 4.5v v in 40v, 0.5a i load 3a circuit of f i gure 2 1.8 1.728/ 1.710 1.872/ 1.890 v v(min) v(max ) LM2576m-2.5, LM2576mk-2.5, LM2576m1k-2.5 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (no t e 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 12v, i load =0.5a circuit of f i gure 2 2.5 2.450 2.550 v v(min) v(max ) v out output voltage 5.2v v in 40v, 0.5a i load 3a circuit of f i gure 2 2.5 2.400/ 2.375 2.600/ 2.625 v v(min) v(max ) LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 4 - silicon link inc. june 2007 rev. 0
LM2576-3.3, LM2576m-3.3, lm 2576mk-3.3 LM2576m1k-3.3 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (no t e 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 12v, i load =0.5a circuit of f i gure 2 3.3 3.234 3.366 v v(min) v(max ) v out output voltage 6v v in 40v, 0.5a i load 3a circuit of f i gure 2 3.3 3.168/ 3.135 3.432/ 3.465 v v(min) v(max ) efficiency v in = 12v, i load =3 a 75 % LM2576-5.0, LM2576m-5.0, lm 2576mk-5.0, LM2576m1k-5.0 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th f i gure 2 b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (note 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in =12v, i loa d =0.5a circuit of fi gure 2 5.0 4.900 5.100 v v(min) v(max) v out output voltage 0.5a i loa d 3a, 8v v in 40v circuit of fi gure 2 5.0 4.800/ 4.750 5.200/ 5.250 v v(min) v(max) efficiency v in =12v, i loa d =3a 77 % LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 5 - silicon link inc. june 2007 rev. 0
LM2576-12, LM2576m-12, lm 2576mk-12, LM2576m1k-12 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (note 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 25v, i load =0.5a circuit of f i gure 2 12 11.76 12.24 v v(min) v(max ) v out output voltage 0.5a i load 3a, 15v v in 40v circuit of f i gure 2 12 11.52/ 11.40 12.48/ 12.60 v v(min) v(max ) efficiency v in = 15v, i load =3 a 88 % LM2576-15, LM2576m-15, lm 2576mk-15, LM2576m1k-15 electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (note 2) units (limits) system parameters (note 3) test circuit figure 2 v out output voltage v in = 25v, i load =0.5a circuit of f i gure 2 15 14.70 15.30 v v(min) v(max ) v out output voltage 0.5a i load 3a, 18v v in 40v circuit of f i gure 2 15 14.40/ 14.25 15.60/ 15.75 v v(min) v(max ) efficiency v in = 18v, i load =3 a 88 % LM2576-adj, LM2576m-adj, LM2576mk-adj, LM2576m1k-adj electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. sy m b o l p a ra me te r conditions ty p limit (note 2) units (limits) system parameters (note 3) test circuit figure 2 v out f eedback voltage v in = 12v, i load =0.5a, v out =5 v circuit of f i gure 2 1.230 1.217 1.243 v v(min) v(max ) v out f eedback voltage 0.5a i load 3a , 8v v in 40v v out =5v circuit of f i gure 2 1.230 1.193/1 .180 1.267/1 .280 v v(min) v(max ) efficiency v in = 12v, i load =3 a, v out =5 v 77 % LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 6 - silicon link inc. june 2007 rev. 0
all output voltage versions electrical characteristics specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. unless otherw i se specified, v in = 12v for the 3.3v, 5v, and adjustable version, v in = 25v for the 12v version, and v in = 30v for the 15v version, , i load = 500ma. sy m b o l p a r a m e t e r c o n d i t i o n s l m 2 5 7 6 - x x l m 2576m-xx l m 2576mk-xx l m 2576m1k-xx units (limits) ty p l i m i t (note 2) device parameters i b f eedback bias current v out = 5 v (adjustable version only ) 50 100/ 500 na f o oscillator frequency (note 8) 52 47/ 42 58/ 63 khz khz (min) khz (max ) v sat saturation voltage i out = 3 a (note 4) 1.4 1.8/ 2.0 v v(max ) dc max duty cy cle (on) (note 5) 98 93 % %(min) i cl current limit (notes 4, 8) 5.8 4.2/ 3.5 6.9/ 7.5 a a(min) a(max ) i l output leakage current (notes 6, 7): output = 0v output = -1v output = -1v 7.5 2 30 ma(max ) ma ma(max ) i q quiescent current (note 6) 5 10 ma ma(max ) i st by standby quiescent current _______ on/off pin = 5 v (off) 5 0 200 a a(max ) LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 7 - silicon link inc. june 2007 rev. 0
all output voltage versions electrical characteristics (continued) specifications w i th standard ty pe face are for t j = 2 5 c, and those w i th b o l d f ace ty p e apply over full operating t e mperature range. unless otherw i se specified, v in = 12v for the 3.3v, 5v, and adjustable version, v in = 25v for the 12v version, and v in = 30v for the 15v version, i load = 500ma. sy m b o l p a r a m e t e r c o n d i t i o n s l m 2 5 7 6 - x x l m 2576m-xx l m 2576mk-xx l m 2576m1k-xx units (limits) ty p l i m i t (note 2) ____ on/off control v ih _______ on/off pin v out = 0v 1.4 2.2/ 2.4 v(min) v il logic input level v out = nominal output voltage 1.2 1.0/ 0.8 v(max ) i ih _______ on/of f pin input current _______ on/off pin = 5 v (off) 1 2 30 a a(max ) i il _______ on/off pin = 0v (on) 0 10 a a(max ) note 1: absolute maximum ratings indicate limits bey ond w h ic h damage to the device may o ccur. operating ratings indicate conditions for w h ich the device is intended to be f unctional, but do not guarantee spec ific performance limits. f o r guaranteed specifications and te st conditions, see the electrical characteristics. note 2: all limits guaranteed at room temperature (standard ty pe face) and at te mperature extremes (bold ty pe face). note 3: external components such as the catch diode, inducto r, input and output capacitors can affect sw itching regulator sy stem performance. w hen the LM2576, LM2576m, lm 2576mk, LM2576m1k is us ed as show n in the f i gure 2 test circuit, sy stem performance w ill be as show n in sy st em parameters section of el ectrical characteristics. note 4: output pin sourcing current. no diode, i nductor or capacitor connected to output. note 5: f eedback pin removed from output and connected to 0v. note 6: f eedback pin removed from output and c onnected to + 12v for the adjustable, 3.3v, and 5v, versions, and + 25v for the 12v and 15v versions, to force the output transistor of f . note 7: v in = 40v. note 8: t he oscillator frequency reduces to approximately 11 khz in the event of an output s hort or an overload w h ich causes the regulated output voltage to drop approximately 40% from the nominal output volt age. t h is self protections feature low e rs the average pow er dissi pation of the ic by low e ring the mi nimum duty cy cle from 5% dow n to approximately 2%. LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 8 - silicon link inc. june 2007 rev. 0
ty pical performance characteristics (circuit of f i gure 2 ) t j = 25c v in = 40v i lo a d = 3 a i lo a d = 200ma v in = 12v normalized at 25c i lo a d = 200ma i lo a d = 3 a -5 5c 25 c 150 c 15v out 5v s a a t v g h a ( ) swi t ch cu rrent (a) e f f i c i e n c y ( % ) i n pu t vo lt a g e ( v ) f e e d b a c k v o l t a g e c h a h g e ( m v ) j unc tio n temper a t ure ( c) swi t ch saturati on vo l t ag e eff ici enc y o sci lato r fre q u e n c y n g e v in = 20v i lo a d = 5 00ma n o rmalized at t j =2 5 c i lo a d = 500ma t j =25 c i lo a d = 3a i lo a d = 1 a i loa d = 200ma l 1 = 15 0 h r in d = 0. 1 ? 3 . 3v, 5v & adj 1 2 v & 15v jun c t i o n t e mpe r atur e ( c) i n put volt a g e ( v ) j un ct io n t e mpe r atur e ( c) o u t p u t v o l t a g e c h a n g e ( ) o u t p u t v o l t a g e c h a n g e ( % ) i n p u t - o u t p u t d i f f e r e n t i a l ( v ) no rmal ized outpu t vo lt ag e li ne reg u la tion dro pou t vo lta g e v in = 4 0 v v ou t = 5 v mea s ur ed at g r ou nd pin t j =2 5c v in = 25 v v in =12 v v on / o f f = 5 v i lo a d = 3a i loa d = 2 00m a j u n c t i o n t e mp er at ure ( c) in p u t v o lt a g e ( v ) j u n c t io n t e m p era t u r e ( c ) s t a n d b y q u i e s c e n t c u r r e n t ( a ) q u i e s c e n t c u r r e n t ( m a ) o u t p u t c u r r e n t ( a ) standby quiescent curre nt quiescent curre nt current l i mit e c o l t a i o n t u r LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 9 - silicon link inc. june 2007 rev. 0
typical performance characteristics (circuit of fi gure 2 ) (continued) v ou t 1.23v i lo a d = 500ma i lo a d = 50 0 m a ad ju st a b le ve r s io n on l y ad ju st a b le ve rs io n on l y v in = 7v v in = 40v i lo a d = 500ma v in = 7v ad ju st a b le ve r s io n on l y v in = 40v duty c y cle ( % ) junction t e mperature ( c ) q u i e s c e n t c u r r e n t ( m a ) o u t p u t c u r r e n t ( a ) min i mu m ope r ating v o ltage quiescent current vs d u ty cycle feedback voltage vs duty cycle i n p u t v o l t a g e ( v ) duty cycle ( % ) a d justa b le v e r s io n o n ly ja = 32 c/ w ja = 37 c/w ja = 5 0 c/ w ja = 73 c/ w maximum power dissipation (to-263) feedback pin current p o w e r d i s s i p a t i o n ( w ) amb ien t t e mp erat ure ( c) f e e d b a c k p i n c u r r e n t ( n a ) ju ncti o n temp era t ure ( c ) LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 10 - silicon link inc. june 2007 rev. 0
ty pical performance characteristics (circuit of f i gure 2 ) (continued) switching waveforms load transient response v out = 15v 5s / d i v a b c d 10 0 s /d iv out p ut vo lt a g e c h an ge lo ad c u rre nt a: output pin voltage, 50v/div b: output pin current, 2a/div c: inductor current, 2a/div d: output ripple voltage, 50mv/div, ac-coupled ho rizo n t al t i me base: 5 s/d i v LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx - 11 - silicon link inc. june 2007 rev. 0
test circuit and lay out guidelines as in any sw itching regulator , lay out is very important. rapidly sw itching currents associated w i th w i ring inductance generate voltage tr ansients w h ich can cause problems. f o r minimal i nductance and ground loops, the length of the leads indicated by heavy lines should be kept as short as possible. single-point grounding (as indicated) or ground plane construction should be used for best results. w hen using the adjustable version, phy si cally locate the programming resistors near the regulator , to keep the sensitive feedback w i ring short. fixed output voltage versions c in ? 100 f , 75v, aluminum electroly t ic c out ?1000 f , 25v, aluminum electroly t ic d1 ? schottky , mbr360 l 1 ? 100 h, pulse eng. pe-92108 r 1 ? 2k, 0.1% v in unregulat e d d c in p u t l m 25 76 h v - fi xe d out p ut +v in l o a d 1 + c in 3 gnd on / o f f out p ut 4 l1 10 0 h d1 mbr3 60 c out 10 00 f 100 f feedback 5 + 2 v ou t - r 2 ? 6.12k, 0.1% adjustable output voltage version ) r r 1 ( v v 1 2 ref out + = 7v - 6 0 v un re gulate d dc i n pu t lm 25 7 6 h v - adj +v in l o a d 1 + c in 3 gn d on/ o ff ou tput 4 l1 10 0 h d1 mb r36 0 c ou t 10 00 f 10 0 f fe edb a ck 5 + 2 v ou t 5.0 0 v r2 r1 - ) 1 v v ( r r ref out 1 2 ? = w here v re f = 1. 23v, r1 bet w een 1k and 5k figure 2. - 12 - silicon link inc. june 2007 rev. 0 LM2576 se rie s LM2576m-xx sim p le switcher 3a lm2 576mk-xx s t ep-down voltage r e gul ator LM2576m1k-xx

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