lm2576 series description the lm2576 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving 3a load w ith excellent line and load regulation. these devices are available in fixed output voltages of 3.3v, 5v, 12v, 15v, and an adjustable output versions. requiring a minimum number of external components, these regulators are simpl e to use and include internal frequenc y compensation and a fi x ed - frequency oscillator. the lm 2576 series o ffers a high - efficiency replacement for popular three - terminal linear regulators. it substantiall y 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 ith the lm 2576 are available from several different manufacturers. this feature greatl y simplifies the design of s w itc h - mode po w er supplies. other features include a guaranteed 4% tolerance on output voltage w ithin specified input voltages and output load conditions, and 10% on the oscillator frequenc y . e x ternal shutdo w n is included, featuring 50 a (t y pical) standb y current. the output s w itch includes c y cle - b y - c y cle current limiting, as w ell as thermal shutdo w n for full protection under fault conditions. note: features ? 3.3v, 5v, 12v, 15v, and adjustable output versions ? adjustable version output voltage range ? 1.23v to 37v (57v for hv version) 4% max over line and load conditions ? guaranteed 3a output current ? wide input voltage range, 40v up to 60v for hv version ? requires onl y 4 external components ? 52 khz fi x ed frequenc y oscillator ? ttl shutdo w n capabilit y , lo w po w er standb y mode ? high efficiency ? uses readil y available standard inductors ? thermal shutdo w n and current limit protection applications ? simple high - efficienc y step - do w n (buck) regulator ? efficient pre - regulator for linear regulators ? on - card s w itching regulators ? positive to negative converter (buck - boost) t y pical application f igure 1.( f ixed output voltage versions) 7v - 40v (60v for hv) unregulated + v in 1 lm2576/ lm2576hv- 5.0 feedback 4 output 2 l1 +5v regulated dc input + 3 gnd c in 5 on/off 10 0 h d1 1n5822 + c out 1 0 0 0 f out p ut 3a load 1 tiger ele ctr o n i c s c o ., l t d tiger electronic co.,ltd
lm2576 series block diagram u n re g u l a t e d d c i n put + v i n 1 4 i n t e r n al r e g ul a to r o n /o f f 5 on / of f c i n f e e d - b a ck r2 f i x e d g a i n e r ror a m p d r iver 3 a m p r1 1 . 0k 1.2 3 v + - co m p a r a t o r + - s w i t c h 2 3 ou tp ut d1 l1 + v o u t c o u t l o a b a n d - g ap 5 2 k hz t h e r m a l c u r r e n t d r e f e r e n c e o s c il l a t o r r e s e t s h u t d o w n l i m i t g n d 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 temperature range output voltage, v package t y pe - 25 c t a 7 5c 3.3 5.0 12 15 a d j lm2576sx-3.3 lm2576sx-5.0 lm2576sx-12 lm2576sx-15 lm2576sx-adj lm2576hvs -3.3 lm2576 hvs -5.0 lm2576hvs -12 lm2576hvs -15 lm2576hvs -adj lm 2576t-3.3 lm2576t-5.0 lm2576t-12 lm2576t-15 lm2576t-adj lm2576hvt-3. 3 lm2576hvt-5.0 LM2576HVT-12 lm2576hvt-15 lm2576hvt-adj to-263 to-220 2 ele ctr o n i c s c o ., l t d tiger
lm2576 series absolute maximum ratings (note 1) paramete r maximu m units maximum suppl y voltage lm 2576 lm 2576hv 45 63 v on/off pin input voltage - 0.3v v +v in output voltage to ground (stead y state) - 1 v po w er dissipation internall y limited w storage temperature range - 65 to +150 c maximum junction temperature 150 c minimum esd rating (c= 100pf, r = 1.5 k ? ) 2 kv lead temperature (soldering, 10 seconds) 260 c operating ratings temperature range lm 2576/lm 2576hv suppl y voltage parameter value units - 4 0 t j +125 c lm 2576 lm 2576hv 40 60 v electrical characteristics lm 2576 - 3.3, lm 2576hv -3.3 3.3 specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. s y mbo l paramete r conditions system p a r a meters (note 3 ) test circui t figure 2 v out output voltage v i n =12v, i l o a d =0.5a circuit of figure 2 lm 2576-3.3 -3.3 lm 2576hv-3.3 t y p limi t (note 2) 3.3 3.234 3.366 units (limits) v v(min) v(ma x ) v out output voltage l m2576 v out output voltage l m2576hv 6v v i n 40v, 0.5a i l o a d 3a circuit of figure 2 6v v i n 60v, 0.5a i l o a d 3a circuit of figure 2 3.3 3.3 3.168/ 3.135 3.432/ 3.465 3.168/ 3.135 3.450/ 3.482 v v(min) v(ma x ) v v(min) v(ma x ) efficiency v i n =12v, i l o a d =3a 75 % electrical characteristics lm 2576 - 5.0, lm 2576hv -5.0 5.0 specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. s y mbo l paramete r conditions system p a r a meters (note 3 ) test circui t figure 2 v out output voltage v i n =12v, i l o a d =0.5a circuit of figure 2 lm 2576 -5.0 5.0 lm 2576hv-5.0 t y p limi t (note 2) 5.0 4.900 5.100 units (limits) v v(min) v(ma x ) v out output voltage l m2576 v out output voltage lm 2576hv 0.5a i l o a d 3a, 8v v i n 40v circuit of figure 2 0.5a i l o a d 3a, 8v v i n 60v circuit of figure 2 5.0 5.0 4.800/ 4.750 5.200/ 5.250 4.800/ 4.750 5.225/ 5.275 v v(min) v(ma x ) v v(min) v(ma x ) efficiency v i n =12v, i l o a d =3a 77 % 3 ele ctr o n i c s c o ., l t d tiger
lm2576 series electrical characteristics lm 2576 - 12, lm 2576hv -12 12 specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. s y mbo l paramete r conditions system p a r a meters (note 3 ) test circui t figure 2 v out output voltage v i n =25v, i l o a d =0.5a circuit of figure 2 lm 2576 -12 1212 lm 2576hv-12 t y p limit (note 2) 12 11.76 12.24 units (limits) v v(min) v(ma x ) v out output voltage lm 2576 v out output voltage l m2576hv 0.5a i l o a d 3a, 15v v i n 40v circuit of figure 2 0.5a i l o a d 3a, 15v v i n 60v circuit of figure 2 12 12 11.52/ 11.40 12.48/ 12.60 11.52/ 11.40 12.54/ 12.66 v v(min) v(ma x ) v v(min) v(ma x ) efficiency v i n =15v, i l o a d =3a 88 % electrical characteristics lm 2576 - 15, lm 2576hv -15 -15 specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. s y mbo l paramete r conditions system p a r a meters (note 3 ) test circui t figure 2 v out output voltage v i n =25, i l o a d =0.5a circuit of figure 2 lm 2576 -15 15lm lm 2576hv-15 t y p limi t (note 2) 15 14.70 15.30 units (limits) v v(min) v(ma x ) v out output voltage lm 2576 v out output voltage lm 2576hv 0.5a i l o a d 3a, 18 v i n 40v circuit of figure 2 0.5a i l o a d 3a, 18 v i n 60v circuit of figure 2 15 15 14.40/ 14.25 15.60/ 15.75 14.40/ 14.25 15.68/ 15.83 v v(min) v(ma x ) v v(min) v(ma x ) efficiency v i n =18v, i l o a d =3a 88 % electrical characteristics lm 2576 - adj, lm 2576hv -adj adj specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. s y mbo l paramete r conditions system p a r a meters (note 3 ) test circui t figure 2 v out feedback voltage v i n =12v, i l o a d =0.5a, v out =5v circuit of figure 2 lm 2576 -adj a d lm 2576hv-adj t y p limit (note 2) 1.230 1.217 1.243 units (limits) v v(min) v(ma x ) v out feedback voltage lm 2576 v out feedback voltage lm 2576hv 0.5a i l o a d 3a , 8v v i n 40v v out =5v circuit of figure 2 0.5a i l o a d 3a, 8v v i n 60v, v out =5v circuit of figure 2 1.230 1.230 1.193/1 .180 1.267/1 .280 1.193/1 .180 1.273/1 .286 v v(min) v(ma x ) v v(min) v(ma x ) efficiency v i n =12v, i l o a d =3a, v out =5v 77 % 4 ele ctr o n i c s c o ., l t d tiger
lm2576 series all output voltage versions electrical characteristics specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. unless other w ise specified, v i n =12v for the 3.3v, 5v, and adjustable version, v i n =25v for the 12v version, and v i n =30v for the 15v version, , i l o a d =500ma. s y mbo l paramete r conditions device p a r a meters lm 2576 -xx xx xxlm lm 2576hv-xx t y p limi t (note 2) units (limits) i b feedback bias current v out =5v (adjustable version onl y ) 50 100/ 500 na f o o scillator frequency (note 8) 52 v sa t saturation voltage i out =3a (note 4) 1.4 d c max dut y c y cle (on ) (note 5 ) 98 i c l current limit (notes 4, 8) 5.8 i l output leakage current (notes 6, 7): output = 0v 47/ 42 58/ 63 1.8/ 2.0 93 4.2/ 3.5 6.9/ 7.5 2 khz khz ( min) khz ( ma x ) v v(ma x ) % %(m i n) a a(min) a(ma x ) ma(max) output = - 1v output = - 1v 7.5 30 ma ma(max) i q quiescent current (note 6) 5 10 ma ma(max) i s t b y standb y quiescent current ___ on/off p i n = 5v (off) 50 200 a a(ma x ) ___ on/off control v ih __ on/off p i n 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(ma x ) i ih i il __ on/off pin input current __ on/off p i n = 5v (off) __ on/off pin = 0v (on) 12 0 30 10 a a(ma x ) a a(ma x ) note 1 : absolute maximum ratings indicate limits be y ond w hich damage to the device ma y occur. operating ratings indicate conditions for w hich the device is intended to be functional, but do not guarantee specific performance limits. for guaranteed specifications and test conditions, see the electrical characteristics. note 2 : all limits guaranteed at room temperature (standa r d t y pe face) and at temperature extremes ( bold t y pe face ). note 3 : external components such as the catch diode, inductor, input and output capacitors can affect s w itching regulator s y stem performance. when the lm 2576/lm 2576hv is used as shown in the figure 2 test circuit, system performance will be a s sho w n in s y stem parameters section of electrical characteristics. note 4 : output pin sourcing current. no diode, inductor or capacitor connected to output. note 5 : feedback pin removed from output and connected to 0v. note 6 : feedback pin removed from output and connected to +12v for the adjustable, 3.3v, and 5v, versions, and +25v for the 12v and 15v versions, to force the output transistor off. note 7 : v i n =40v (60v for high voltage version). note 8 : the oscillator frequenc y reduces to appro x imatel y 11 khz in the event of an output short or an overload w hich causes the regulated output voltage to drop approximatel y 40% from the nominal output voltage. this self protections feature lo w ers the average po w er dissipation of the ic b y lo w ering the minimum dut y c y cle from 5% do w n to approximatel y 2%. 5 ele ctr o n i c s c o ., l t d tiger
lm2576 series t y pical performance characteristics (circuit o f f igure 2 ) n or m a l i z e d ou t pu t v o l t a g e l i n e r e g u l a t i on d r opou t v o l t a ge v i n = 20v i l oa d = 50 0 m a n o r m al i z e d a t t j = 25 c i l oa d = 50 0 m a t j = 25c i l oa d = 3 a l 1 = 150 h 3 . 3 v , 5 v & a d j 1 2v & 15v i l oa d = 20 0 m a i l oa d = 1 a r i nd = 0.1 ? j unctio n t e m p e r a t u re ( c ) in p u t v o l t ag e ( v ) j unctio n t e m p e r a t u re ( c) st a n d by qu i e s c e n t c ur r e n t qu i e s c e n t c ur r e n t c u r r e n t li m it v i n = 25v v i n = 40v v o u t = 5v m e a s u r e d at g r ound p i n v o n / o f f = 5v t j =2 5c v i n =12 v i l o a d = 200ma i l o a d = 3a ju n c t i o n t emp e r a t ure ( c) i n p ut vo l t a ge (v) ju n c t io n t emp e r a t ure ( c) s w i t c h s a t u r a t i on v o l t a g e e f f i c i e n c y osc i l a t o r f r e qu e n cy no r m al iz ed a t 25 c - 55 c i l oa d = 3 a 1 5 v o u t t j = 25 c i l oa d = 20 0 m a v i n = 40 v 2 5 c 1 5 0 c 5v i l oa d = 3 a i l oa d = 20 0 m a v i n = 12 v s wi t c h c urr e n t ( a ) i n p u t v o l t a g e (v ) j un c t i o n t e m p e r a t u r e ( c) m i ni m u m op era t in g v o l t a g e qu i e s ce n t c u rre n t vs d u t y cy cl e f ee db ack v ol t a g e vs d u t y cyc l e a dj u st a b l e v e r si o n o n l y a d j u st a b l e v e r s i on on l y v i n = 7v a d j u st a b l e v e r s i o n o n l y i loa d = 5 0 0 m a v in = 4 0 v v o u t 1.23v i lo a d = 500ma i load = 50 0 m a v i n = 40v v in = 7v j u n c t i on te mpe r a tu r e (c) d u ty c y c l e ( % ) d u ty c y c l e ( % ) 6 ele ctr o n i c s c o ., l t d tiger
lm2576 series all output voltage versions electrical characteristics specifications w ith standard t y pe face are for t j = 25 c, and those w ith boldface t y p e appl y over full operating temperature range. unless other w ise specified, v i n =12v for the 3.3v, 5v, and adjustable version, v i n =25v for the 12v version, and v i n =30v for the 15v version, , i l o a d =500ma. s y mbo l paramete r conditions device p a r a meters lm 2576 -xx xx xxlm l m 2576hv-xx t y p limi t (note 2) units (limits) i b feedback bias current v out =5v (adjustable version onl y ) 50 100/ 500 na f o o scillator frequency (note 8) 52 v sa t saturation voltage i out =3a (note 4) 1.4 d c max dut y c y cle (on ) (note 5 ) 98 i c l current limit (notes 4, 8) 5.8 i l output leakage current (notes 6, 7): output = 0v 47/ 42 58/ 63 1.8/ 2.0 93 4.2/ 3.5 6.9/ 7.5 2 khz khz ( min) khz ( ma x ) v v(ma x ) % %(m i n) a a(min) a(ma x ) ma(max) output = - 1v output = - 1v 7.5 30 ma ma(max) i q quiescent current (note 6) 5 10 ma ma(max) i s t b y standb y quiescent current ___ on/off p i n = 5v (off) 50 200 a a(ma x ) ___ on/off control v ih __ on/off p i n 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(ma x ) i ih i il __ on/off pin input current __ on/off p i n = 5v (off) __ on/off pin = 0v (on) 12 0 30 10 a a(ma x ) a a(ma x ) note 1 : absolute maximum ratings indicate limits be y ond w hich damage to the device ma y occur. operating ratings indicate conditions for w hich the device is intended to be functional, but do not guarantee specific performance limits. for guaranteed specifications and test conditions, see the electrical characteristics. note 2 : all limits guaranteed at room temperature (standa r d t y pe face) and at temperature extremes ( bold t y pe face ). note 3 : external components such as the catch diode, inductor, input and output capacitors can affect s w itching regulator s y stem performance. when the lm 2576/ l m2576hv is used as shown in the figure 2 test circuit, system performance will be a s sho w n in s y stem parameters section of electrical characteristics. note 4 : output pin sourcing current. no diode, inductor or capacitor connected to output. note 5 : feedback pin removed from output and connected to 0v. note 6 : feedback pin removed from output and connected to +12v for the adjustable, 3.3v, and 5v, versions, and +25v for the 12v and 15v versions, to force the output transistor off. note 7 : v i n =40v (60v for high voltage version). note 8 : the oscillator frequenc y reduces to appro x imatel y 11 khz in the event of an output short or an overload w hich causes the regulated output voltage to drop approximatel y 40% from the nominal output voltage. this self protections feature lo w ers the average po w er dissipation of the ic b y lo w ering the minimum dut y c y cle from 5% do w n to approximatel y 2%. 5 ele ctr o n i c s c o ., l t d tiger
lm2576 series test circuit and la y out guidelines as in an y s w itching regulator, la y out is ver y important. rapidl y s w itching currents associated w ith w iring inductance generate voltage transients w hich can cause problems. for minimal inductance and ground loops, the length of the leads indicated b y heav y lines should be kept as short as possible. single - point grounding (as indicated) or ground plane construction should be used for best results. when using the adjustable version, ph y sicall y locate the programming resistors near the regulator, to keep the sensitive feedback w iring short. fixed outpu t voltage versions ( f igure 2a) unr egul a ted + + v in 1 lm 2576hv- f i x e d o u tp u t o n / o f f f ee d b ack 4 o utput 2 l 1 1 00 h d 1 v o u t l o v in d c i nput g n 100 f d 3 5 + m br 3 60 c o u t 100 0 f a d c i n ? 100 f, 75v, aluminum electrol y tic c out ? 1000 f, 25v, aluminum electrol y tic d1 ? schottk y , mbr360 l 1 ? 100 h, pulse eng. pe - 92108 r 1 ? 2k, 0.1% r 2 ? 6.12k, 0.1% adjustable output voltage version ( f igure 2b) 7 v - 6 0v + v in 1 1 0 0 f lm 2576hv- ad j f ee d ba c k 4 o u t p u t 2 l1 1 0 0 h v o u t 5 . 0 0 v l u n r e g u l a t e d d c i n p ut + c in g n d 3 o n/ o f f 5 + c o u t r2 o a m b r 3 6 0 1 0 0 0 f r1 d v out = v ref 1 ( + r 2 ) r r r ( v out ) 1 2 1 v ref ? where v re f = 1.23v, r1 between 1k and 5k r e v n o : 01 - 0 6 08 13 8 ele ctr o n i c s c o ., l t d tiger
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