quick st ar t guide for demonstra tion circuit 441 1.25a synchronous buck regula tor l t c3411 description demonstratio n cir c uit 441 is a constant-frequency step- down converter , using the l t c3411 monolithic synchro- nous buck r e gulator . the dc441 has an input volt age range of 2.65v to 5.5v , an d is capable of delivering up to 1.25a of out put current. in burst mod e ? operation, the dc supply current is typically only 240a at no load , and less than 1a in shutdow n. in switching-noise sensitive applications, pulling the mode pin to sgnd in hibits burst mode ? operation. these features, plus the l t c3411 coming in a small 10-pin ms package and hav- ing an operating frequency of 1mhz (allowing the exclu- sive use of low profile sur f ace mount compone nts), make the dc441 demo board an ideal cir c uit for u se in batter y -powered, hand-held applications. d e sign files for this circ uit board ar e availab l e. call the l t c factor y . quick st art procedure demonstratio n cir c uit 441 is easy to set up to eval uate the per f ormance of the l t c3411. refer to figure 1 for proper measurement equipment setup and f o llow the procedure below: note: when measu ring the output ripple, s ee figure 2 for proper scope probe technique. 1. select the desired output voltage using jumper jp2. the fixed output voltages are 1.8v , 2 . 5v , and 3.3v (as shown). there is also an o p tion to set t h e outpu t vol t - age to a custom value by inserting a resistor into the rf b5 pads n ext to jumper jp2. 2. connect the input power supply to the vin and gnd terminals on the left-side of the board. do not hot- plug vin or increase vin over the rated maximu m supply voltage of 5.5v , or the part may be damaged. 3. connect the load between the v out and gnd termi- nals on the right-side of the board. 4. select the desired operating mode usi ng jp1. t o s e - lect pulse-skipping mode, tie to ground by insertin g the jumper into the rightmost position. inserting the jumper into the leftmost position conne cts the pin t o vin, which allows burst mode ? operation. 5. t o shut down the cir c uit, connect the shdn/r t pin to sv in by inse rting the jp3 jumper into the rightmo st position. v s + ? + ? + ? + ? + ? + ? load figure 1. prope r measur ement equipme n t setup vin gnd figure 2. scope probe placement for me asuring output ripple 1
5 5 4 4 3 3 2 2 1 1 d d c c b b a a sy nc 2.65v-5. 5v 3. 3v 2. 5v 1. 8v vin 3.3v/2 .5v/1.8v vou t 1. 25a gnd gnd gnd pgo od ci n1 ci n2 u1 co ut1 co ut2 l1 rpg rsw rfb1 cf fw rse t rc cc pcb silkscr een opt . jp2 c1 burst mode pulse-ski p on off ltc 3411ems /m ode a demo DC441A monday, march 11, 2002 1 1 buck regulator: 2.65v-5.5 v->1.8v, 2.5v, or 3.3v@1.25a(max) june wu 6/28/01 tom gross 6/28/01 siz e sc ale: cage code dwg no rev sheet of file name: titl e contr act no. app rovals da te drawn checked approved engineer designer technolog y 16 30 mccarthy blvd. milpitas, ca 95035 phone: (408)4 32-1900 fax: (408)434-0 507 vi n co ut2 1u f op t. 7 8 d1 opt . 2 1 co ut4 opt . rf b3 412k, 1% rsd 4.7m rf b2 698k, 1% rp g 100 k cin1 10u f 6. 3v rf b1 887k, 1% ci n2 1u f op t. rfil t 0 ci n4 47 uf 16v rf b5 opt . cbyp opt . e5 jp3 1 2 3 u1 ltc 3411ems 6 8 7 2 3 5 1 10 9 4 pvin pgood svin sy/mode sgnd pgnd sd/rt ith vfb sw cc 100 0pf e1 1 2 e2 rs1 1m e7 rset 324 k jp1 1 2 3 rs2 1m l1 2.2 uh cin3 opt . e6 r1 10k co ut3 0.1uf c1 opt . cou t1 22 uf 6. 3v cffw 10p f rf b4 280k, 1% 3 4 e4 rsw opt . 1% e3 rc 16 .2k 5 6
linear technology corporation ltc3411ems confidential bill of material demo bd. #441a item qty reference part description manufacture / part # pkg qty 1 0 cbyp,cout2,cin2 (opt) cap., 0603 2 1 cc cap., x7r, 1000pf, 25v, 20% 0402 avx, 04023c102mat 965 3 1 cffw cap., npo, 10pf, 50v, 10% 0402 avx, 04025a100kat 930 4 1 cout1 cap., x5r, 22uf, 6.3v, 10% 1210 murata, grm32dr60j226ka01 470 5 1 cin1 cap., x5r, 10uf, 6.3v, 10% 1206 murata, grm31cr60j106kc01 475 6 0 cout4,cin3 (opt) cap., 6032, 7343 7 1 cout3 cap., x7r, 0.1uf, 16v, 20% 0603 avx, 0603yc104mat 780 8 1 cin4 cap., tant., 47uf, 16v, 20% 6032 avx, tajc476m016r 468 9 0 c1 (opt) cap., 402 10 0 d1 (opt) diode, sma 11 7 e1-e7 testpoint, turret, .094" mill-max, 2501-2 3345 12 2 jp1,jp3 0.079 single row header 3 pin comm con, 2802s-03-g1 1117 13 1 jp2 0.079x4 double row header comm con, 2202s-08-g1 463 14 3 jp1,jp2,jp3 shunt, comm con, ccij2mm-138g 1403 15 1 l1 inductor, 2.2uh d52lc toko, a914byw-2r2m 509 16 1 rc res.,chip, 16.2k, 1/16w, 5%, 0402 aac, cr05-1622fm 1000 17 1 r1 res.,chip, 10k, 1/16w, 5%, 0402 aac, cr05-103jm 550 18 1 rfb1 res.,chip, 887k, 1/16w, 1% 0402 aac, cr05-8873fm 960 19 1 rfb2 res.,chip, 698k, 1/16w, 1% 0402 aac, cr05-6983fm 920 20 1 rfb3 res.,chip, 412k, 1/16w, 1% 0402 aac, cr05-4123fm 965 21 1 rfb4 res.,chip, 280k, 1/16w, 1% 0402 aac, cr05-2803fm 960 22 0 rfb5 (opt) res., 1% 0402 23 1 rfilt res.,chip, 0, 1/16w, 0402 a ac, cj05-000m 760 24 1 rpg res.,chip, 100k, 1/16w, 5% 0402 aac, cr05-104jm 930 25 1 rse t res.,chip, 316k, 1/16w, 1% 0402 a ac, cr05-3163fm 960 26 0 rsw (opt) res., 0402 27 2 rs1,rs2 res.,chip, 1m, 1/16w, 5% 0402 aac, cr05-105jm 1540 28 1 rsd res.,chip, 4.7m, 1/16w, 5% 0402 aac, cr05-475jm 960 29 1 u1 i.c., ltc3411, ms10 linearl, ltc3411ems 459 30 1 printed circuit boards demo board DC441A 456 31 1 stencil stencil DC441A 32 1 s / f s / frame, #10679, @ flairis 1 6-boards to alan 3/15/02 page 1 - of - 1
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