t d38 4 2a / 38 4 3a / 3844a / 3845a 1 high performance curre nt mode p w m cont rollers descript ion f e a t ures dip-8 sop-8 tmc t o p v i e w compensation v oltage feedback current sense r t /c t v r e f v cc output gnd p in connections 1 2 3 4 8 7 5 6 b lock diagram n o t e 1 : t o g g l e f l i p f l o p u s e d o n l y i n 3 8 4 4 a a n d 3 8 4 5 a . t h e t d3 8 4 2 a / 3 8 4 3 a / 3 8 4 4 a / 3 8 4 5 a a r e f i x e d f r e q u e n c y c u r r e n t - m o d e pw m co n t r o ller . th ey are sp ecia l ly d e sig n ed f o r of f - lin e an d dc - t o - dc con v erte r ap p licatio n s w i th m i n i m u m ex ter n al c o m p o n en ts. these in te g r a t ed c i r cu its f eatu r e a trim med o s cillato r f o r p r ecise d u ty cycle co n t r o l, a tem p eratu r e co m p en sated r ef e r en ce, h i g h g a i n e r r o r a m p l i f i e r . c u r r e n t se n s i n g c o mp a r a t o r , a n d a h i g h cu r r en t to te m p o l e o u tp u t id eally su ited f o r d r iv in g a p o wer m o sfet . pr o t ec tio n c i r cu i ty i n clu d es built in u n d e r - v o l t a g e l o c k o u t a n d c u r r e n t l i m i t i n g . t h e t d3 8 4 2 a a n d t d 3 8 4 4 a h a v e u v l o t h r e s h o l d s o f 1 6 v ( o n ) a n d 1 0 v ( o f f ) t h e t d 3 8 4 3 a a n d t d 3 8 4 5 a a r e 8 . 4 v ( o n ) a n d 7 . 6 v ( o f f ) t h e t d3 8 4 2 a a n d t d3843a c a n o p e r a t e w i t h i n 1 0 0 % d u t y c y c l e . t h e td 3 8 4 4 a a n d t d 3 8 4 5 a can o p erate with 5 0 % d u ty cy cle. ? l o w start up c u r r e n t ? m ax im u m d u ty clam p ? uvlo w ith hy steresis ? o p e r a t i n g f r e q u e n c y u p t o 5 0 0 k h z .com .com .com 4 .com u datasheet
2 tm c ma ximum r a t ing s r ating s ymbol v alue unit b ias and driver v oltages (zero s eries impedance, s ee als o t otal device s pec) v c c , v c 30 v t otal p ower s upply and zener c urrent (i c c + i z ) 30 ma output c urrent, s ource or s ink (note 1) i o 1.0 a output e nergy (c apacitive load per c ycle) w 5.0 m j c urrent s ens e and v oltage f eedback inputs v in - 0.3 to + 5.5 v e rror amp output s ink c urrent i o 10 ma p ower dis s ipation and t hermal c haracteris tics d s uf fix, p las tic p ackage maximum p ower dis s ipation @ t a = 25 c t hermal r es is tance, j unction-to-air n s uf fix, p las tic p ackage maximum p ower dis s ipation @ t a = 25 c t hermal r es is tance, j unction-to-air p d r q j a p d r q j a 862 145 1.25 100 mw c /w w c /w operating j unction t emperature t j + 150 c operating ambient t emperature t a 0 to + 70 c s torage t emperature r ange t s tg - 65 to + 150 c 1. maximum p ackage power dis s ipation limits mus t be obs erved. e l e c t r ic a l c ha r a c t e r is t ic s (v c c = 15 v , [note 2], r t = 10 k, c t = 3.3 nf , t a = t low to t high [note 3], unles s otherwis e noted.) t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a c harac teris tic s s ymbol min t y p max unit r e f e r e nc e s e c t ion r eference output v oltage (i o = 1.0 ma, t j = 25 c ) v ref 4.9 5.0 5.1 v line r egulation (v c c = 12 v to 25 v ) r eg line - 2.0 20 mv load r egulation (i o = 1.0 ma to 20 ma) r eg load - 3.0 25 mv t emperature s tability t s - 0.2 - mv / c t otal output v ariation over line, load, t emperature v ref 4.82 - 5.18 v output nois e v oltage (f = 10 hz to 10 khz, t j = 25 c ) v n - 50 - m v long t erm s tability (t a = 125 c for 1000 hours ) s - 5.0 - mv output s hort c ircuit c urrent i s c - 30 - 85 - 180 ma os c il l a t or s e c t ion f requency t j = 25 c t a = t low to t high f os c 47 46 52 - 57 60 khz f requency c hange with v o ltage (v c c = 1 2 v t o 2 5 v ) d f os c/ d v - 0.2 1.0 % f requency c hange with t emperature t a = t low to t high d f os c/ d t - 5.0 - % os cillator v oltage s wing (p eaktop eak) v os c - 1.6 - v dis charge c urrent (v os c = 2.0 v ) t j = 25 c t a = t low to t high i dis chg 7.5 7.2 8.4 - 9.3 9.5 ma t d38 4 2a / 38 4 3a / 3844a / 3845a .com .com .com .com 4 .com u datasheet
t d38 4 2a / 38 4 3a / 3844a / 3845a 3 tmc e r r or a mp l if ie r s e c t ion v oltage f eedback input (v o = 2.5 v ) v f b 2.42 2.5 2.58 v input b ias c urrent (v f b = 2.7 v ) i ib - -0.1 -2.0 m a open loop v oltage g ain (v o = 2.0 v to 4.0 v ) a v o l 65 90 - db unity g ain b andwidth (t j = 25 c ) b w 0.7 1.0 - mhz p ower s upply r ejection r atio (v c c = 12 v to 25 v ) p s r r 60 70 - db output c urrent s ink (v o = 1.1 v , v f b = 2.7 v ) s ource (v o = 5.0 v , v f b = 2.3 v ) i s ink i s ource 2.0 -0.5 12 -1.0 - - ma output v oltage s wing high s tate (r l = 15 k to ground, v f b = 2.3 v ) low s tate (r l = 15 k to v ref , v f b = 2.7 v ) v oh v ol 5.0 - 6.2 0.8 - 1.1 v 2. adjus t v c c above the s tartup thres hold before s etting to 15 v . 3. low duty cycle puls e techniques are us ed during tes t to maintain junction temperature as clos e to ambient as pos s ible. t l o w = 0 c f o r t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a t h i g h = + 7 0 c f o r t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a e l e c t r ic a l c ha r a c t e r is t ic s (v c c = 15 v , [note 4], r t = 10 k, c t = 3.3 nf , t a = t low to t high [note 5], unles s otherwis e noted.) c harac teris tic s s ymbol min t y p max unit c ur r e nt s e ns e s e c t ion c urrent s ens e input v oltage g ain (notes 6 & 7) a v 2.85 3.0 3.15 v /v maximum c urrent s ens e input t hres hold (note 6) v th 0.9 1.0 1.1 v p ower s upply r ejection r atio v c c = 12 to 25 v (note 6) p s r r - 70 - db input b ias c urrent i ib - -2.0 -10 m a p ropagation delay (c urrent s ens e input to output) t p lh(in/out) - 150 300 ns out p ut s e c t ion output v oltage low s tate (i s ink = 20 ma) low s tate (i s ink = 200 ma) high s tate (i s ink = 20 ma) high s tate (i s ink = 200 ma) v ol v oh - - 13 12 0.1 1.6 13.5 13.4 0.4 2.2 - - v output v oltage with uv lo activated v c c = 6.0 v , i s ink = 1.0 ma v ol(uv l o) - 0.1 1.1 v output v oltage r is e t ime (c l = 1.0 nf , t j = 25 c ) t r - 50 150 ns output v oltage f all t ime (c l = 1.0 nf , t j = 25 c ) t f - 50 150 ns unde r v ol t a g e l oc k out s e c t ion s t a r t u p t h r e s h o l d t d 3 8 4 2 a / t d 3 8 4 4 a t d 3 8 4 3 a / t d 3 8 4 5 a v th 14.5 7.8 16 8.4 17.5 9.0 v m i n i m u m o p e r a t i ng v o l t a g e a f t e r t u r n o n td 3 8 4 2 a / t d 3 8 4 4 a t d3843 a / t d 3 8 4 5 a v c c (min) 8.5 7.0 10 7.6 1 1.5 8.2 v t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a c harac teris tic s s ymbol min t y p max unit .com .com .com .com 4 .com u datasheet
4 tmc p wm s e c t ion duty c ycle m aximum m inimum dc max dc min 94 - 96 - 100 0 % t o t a l de v ic e p ower s upply c urrent (note 4) s tartup: (v c c = 6 . 5 v f o r t d 3 8 4 3 a , (v c c = 1 4 v f o r t d 3 8 4 2 a ) o p e r a t i ng i c c - - 0.5 12 1.0 17 ma p ower s upply zener v oltage (i c c = 25 ma) v z 30 36 - v 4. adjus t v c c above the s tartup thres hold before s etting to 15 v . 5. low duty cycle puls e techniques are us ed during tes t to maintain junction temperature as clos e to ambient as pos s ible. t l o w = 0 c f o r t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a t h i g h = + 7 0 c f o r t d 3 8 4 2 a / 4 3 a / 4 4 a / 4 5 a 6. t his parameter is meas ured at the latch trip point with v f b = 0 v . 7. c omparator gain is defined as : a v d v output c ompens ation d v c urrent s ens e input c harac teris tic s s ymbol min t y p max unit o u t p u t / c o m p e n s a t i o n c u r r e n t s e n s e i n p u t l a t c h ` ` r e s e t ' ' input o u t p u t c a p a c i t o r c t l a t c h ` ` set' ' input l a r g e r t / s m a l l c t small r t /large c t f igure 1. t iming diagram t d38 4 2a / 38 4 3a / 3844a / 3845a t d3842a/tdd3843a t d3844a/tdd3845a 4 7 4 8 5 0 .com .com .com .com 4 .com u datasheet
5 tmc oscillat o r sect i on 5 4 8 rt ct large rt small ct small rt large ct v4 v4 internal clock internal clock dead t i m e v s c t ( r t >5k w ) ti m i ng res i s t anc e v s frequenc y 1 10 100 1 1 0 100 0.1 td ( m s ) ct (nf) 100 1 10 6 10 5 10 4 10 3 10 10 2 rt (k w ) frequency (hz) ct=1nf ct=2.2nf ct=4.7nf ct=10nf ct=22nf ct=47nf ct=100nf shut dow n t e chniques 8 3 330 500 1k 1 shutdown to current sense resistor shutdown sh u t do w n t d3842a c an be ac c o m p li s h ed by t w o m e t hod s ; ei t h er r a is e pin 3 abo v e 1v or p u ll pi n 1 b e low a v o lt age t w o dio d e drop s abo v e groun d. eit her m e t h o d c a u s e d t h e out p u t o f p w m c o m par at or t o be hig h ( r e f e r t o bloc k diag r a m ) . t he p w m la t c h i s r e s e t do m i na nt s o t h a t t h e o u t put w ill re m a in low unt il t h e n e x t c l o c k c y c l e aft e r t h e s h u t dow n c ond it ion a t pin s 1 and/ or 3 is re m o v e d. i n on e ex am ple , an ex t e r n ally la t c hed s h ut ?dow n m a y be ac c o m p li s h ed by addi ng an sc r w h ic h b e r e s e t by c y c lin g v c c b e low t he low e r u v lo t h r e s hold . a at t h i s poi nt t h e re f e r e nc e t u r n s o f f allow i ng t h e s c r to r e s e t. t y pical performance charact erist i cs 0.01 0.1 1 0 1 2 3 4 s a t u r a t i on v o lt age ( v ) output current ( sourse or sink current) (a) vcc=15v ta=+25c ta=-55c 7 10 3 10 6 10 5 10 4 10 10 2 10 0 20 40 60 100 80 frequency (hz) v o lt age g a in ( d b ) -180 -135 -90 -45 0 ph ase (d e g r e e ) out put s a t u r at i on charac t e r i s t i c s e r r or a m pl i f i e r open-loop frequenc y res pons e t d38 4 2a / 38 4 3a / 3844a / 3845a .com .com .com .com 4 .com u datasheet
6 tmc - 50 - 25 0 2 5 5 0 7 5 100 125 150 4.96 4.97 4.98 4.99 5.00 5.01 5.02 vref (v) temperature (c) v cc=15v io=1ma -50 -25 0 2 5 5 0 7 5 100 125 150 250 300 350 400 450 500 550 i s ta r t ( m a ) temperature (c) vcc=9v - 50 - 25 0 2 5 5 0 7 5 100 125 150 9 10 11 12 13 14 15 icc (ma) temperature (c) v cc=15v io=1ma v r ef temperature drift istart temperature drift icc temperature drift o p e n- l o o p labo rat o ry t e s t f i x t ure 1 2 8 7 3 6 4 5 a v ref v c c 1k / 1w 0. 1 f ct rt 100k 5k 4. 7k 4. 7k 0. 1 f e r ror amp a djust i s ens e adj u s t output h i gh peak c u r r ent as s o c i at ed w i t h c apac it y loads nec es s i t a t e c a r ef u l grounding t e c hniques . t i m i ng and by pas s c apac it ors s hould be c onnec t ed c l os e t o pin 5 in s i ngle point gn d . t he t r ans is t o r and 5k w pot ent io-m et er are us ed t o s a m p le t he os c illat o r w a v e f o r m and apply an adj us t able r a m p t o pin 3. under-volt a ge lockout 7 v c c von=16v, v off=10v on/off command to rest of ic v on v off <1ma <15ma icc v cc d u r ing u n d e r - v olt age lo c k ou t , t he out pu t dri v er i s bia s e d t o a h i gh im p edan c e s t at e. p i n 6 s houl d be s hunt t o gn d w i th a bleeder resistor to prev ent activ a ting the pow er sw itch w i th output leakage currents. t d3842a/44a von=8.4v, v off=7.6v td3843a/45a t d38 4 2a / 38 4 3a / 3844a / 3845a .com .com .com .com 4 .com u datasheet
7 tmc e rror amplifier configurat i on 2 1 0.5ma 2.5v zf zi e r r or am pl i f i e r c an s ourc e or s i nk up t o 0. 5m a current sense circuit 5 3 1 2r r1 v c rs r is error amplifier current sense comparator p eak c u r r ent (i s ) det erm i ned by t he f o r m ul a: is(m a x ) = 1 .0 v /r s . a s m al l rc f i l t er be requi r ed t o s uppres s s w i t c h t r ans i ent s . s lo p e co m p e nsat io n 8 4 3 isense r1 r2 rsense c rt ct 0.1 f a f r ac t i on of t he os c illat o r ram p c an be res i s t i v e ly s u m m ed w i t h t he c u r r ent s ens e s i gnal t o prov ide s l ope c o m pens at ion f o r c onv ert s requiring dut y c y c l es ov er 50%. n ot e t hat c apac it or c , f o r m s a f ilt er w i t h r 2 t o s uppres s t he leading edge s w it c h s p ik es . t d38 4 2a / 38 4 3a / 3844a / 3845a .com .com .com 4 .com u datasheet
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