LI NI U K thut in t hin nay rt pht trin, n uc p dng rt nhiu vo cc lnh vc nh t ng ho, sn sut cng nghp v cn nhiu lnh vc khc na. Cng vi s pht trin ca nn kinh t v khoa hc k thut trn con ng cng nghip ho v hin i ho t nc. Ngnh in t ni chung c nhng bc tin vt bc v mang li nhng thnh qu ng k. Ngy nay vic p dng cng ngh thng tin vo cc lnh vc kh a dng,. Vic p dng CNTT vo in t cng vy, tr gip ngi thit k mch chuyn nghip, tp on Cadence cho ra i phn mm v mch Orcad . Orcad l mt phn mm chuyn dng rt mnh vi giao din rt thn thin, cch s dng n gin. Chng c th v mch nguyn l vi OrCAD Capture, chy m phng vi Pspice, c bit l chc nng v mch in rt mnh vi OrCAD layout, cng vi mt th vin linh kin khng l c hu ht cc nh sn xut linh kin in t cung cp cho OrCAD.. cc sinh vin c tng kh nng t duy v lm quen vi cng vic thit k, ch to chng em c c giao cho thc hin n: Thit k mch n led sng theo m nhc nhm cng c v mt kin thc trong qu trnh thc t. Vi nhng kin thc hc c t thy c gio cng thm ti liu tham kho tuy c th hon thnh n ny nhng khng th trnh khi nhiu thiu st, chng em rt mong nhn uc s dy bo ca thy c v kin ng gp ca cc bn. Chng em chn thnh cm n c gio : dy cho chng em nhng kin thc c bn chng em c th hon thnh n.

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Nhn xt ca gio vin: ................................................................................................................. ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ........................................................................................................................... ...........................................................................................................................

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ti: Mch n Led sng theo m nhc Tm tt bo co: Phn I: C s l thuyt Tm hiu phn tch IC AN6884 Phn II: ng dng Orcad v mch Cc bc tin hnh v mch Schematic Cc bc tin hnh v mch Layout

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Phn I: C s l thuyt IC AN6884 L 1 khi tng hp mch iu khin 5 led hin th biu dng ct ty theo tn hiu vo. kt hp hiu chnh h s khuch i bng bin tr u vo. p dng vi tn hiu AC, DC vi mc o kh rng. c tnh: Khong bin thin in th hot ng: Vcc=3.5~16V Dng in ra: I led=15mA Led sng khi khi tn hiu vo mc thp 5 led thanh p ng theo logarit vi cc mc: -10, -5, 0, 3, 6dB Thnh phn linh kin bn ngoi rt it. S nguyn l cu to ca AN6884:

Nhn vo s cu to ta thy bn trong AN6884 gm c 6 b OPAM. Trong 1 OPAM c tc dng khuch i tn hiu vo(Vin) v 5 OPAM4

cn li c vai tr nh mch so snh. Tn hiu v c so snh vi Vref. Ta c th thay i Vref bng cch lp them bin tr phn p Vref. Th t chn cu AN6884 nh sau: S Pin 1 2 3 4 5 6 7 8 9 Tn Pin LED 1 input LED 2 input LED 3 input LED 4 input GND LED 5 input AMP output AMP input Vcc

Mch test hot ng ca AN6884 theo datasheet:

Thit k mch: T cu to bn trong ca AN6884 chng em thit k 3 b AN6884 chung mt tn hiu vo, nhng gi tr Vref (in p tham chiu) s c chnh bng5

3 bin tr, nh vy ta c 15led vi 3 hng led sng theo nhc vi mc in p tham chiu khc nhau, kt qu thu c hiu ng led sng theo nhc kh th v. S mch nh sau:

Mch ngun s dng IC KA7805 n nh in p 5V cung cp cho AN6884 hot ng. AN 6884 c th hot ng mc in p t 3-18V nhng chng em dng 7805 n nh gi tr in p tham chiu (Vref).

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Phn II: ng dng Orcad v mch 1, Mch nguyn l. Ban u chng ta s tin hnh thit k mch nguyn l, trc tin chng ta khi ng phn mm thit k mch nguyn l Orcad Capture:Khi ng Orcad vi chng trnh Capture hoc Capture CIS.

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To mt project mi nh sau: Chn menu file >> new >> project.

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Chn tn file v a ch ng dn cho file va to:

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Sau khi chng ta chn xong ng dn kt thc qu trnh u tin l to mt file mi cho thit k. Sau y chng ta s trc tip giao tip vi giao din ca Orcad thit k mch, tm linh kin ta c th lm nh sau:

Nhn P Chn biu tng Hoc chn PlacePart.

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Ta thy rng mch ny gm c: 7 in tr, 8 t ha, 2 t gm, 16led(5mm), 3 IC AN6884, 1 IC 7805, 1 connector 1, 1 connector 2.

Ban u chng ta s ly in tr:

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Chng ta s ly ht s in tr cn thit cho mch:

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Lp li qu trnh trn vi cc linh kin tip theo: - T ha: s lng = 8

T gm: s lng = 2

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Led 5mm: s lng = 15

IC 7805: s lng =1

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Conector 1: s lng =1

Conector 2: s lng =1

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AN 6884 l linh kin khng c trong th vin Orcad do vy chng ta cn to linh kin mi, chn File-NewLibrary:

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t tn cho linh kin mi v chn ng dn, sau y l giao din tolinh kin mi:

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Dng cng c Place rectangle trn thanh cng c v hnh ch nht.

V Hnh ch nht xong ch place Pin v chn linh kin. Ti mc Name chn tn chn. Number : s chn v.v..

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. Sau khi to cc tn chn v s chn linh kin tng ng ta c c linh kin AN 6884 nh hnh sau:

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Thm An 6884 va to vo th vin, ta tip tc ly thm 3 IC AN 6884. V cui cng khi ly ht tt c cc linh kin s c hnh sau:

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Tip theo ta sp xp linh kin theo s mch

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Ni cc linh kin vi nhau. Cui cng ta c s mch nguyn l nh sau:

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Kim tra xem mch va v c li hay khng:

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To file netlist c ui *.MNL:

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Sau khi to xong file c ui *.MNL chng ta s khi ng ORCAD Layout:

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To file mi . Load file DEFAULT.TCH

Load file netlist:

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Chn ng dn lu tn mch layout:

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Phn mm s a ra mt thng bo l khng tm thy s chn ca linh kin c tn l Resistor vi k hiu R1, khi chng ta cn tm mt s chn sao cho ph hp vi linh kin ngoi thc t:

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Nh y th linh kin u tin l in tr R1 chng ta vo th vin chn JUMPER :

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Tng t vi cc linh kin khc chng ta cng lm tng t: T:

Bin tr:

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IC 7805:

Led 5mm:

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Connector 2:

IC AN 6884 khng c trong th vin nn cn phi to footprint mi:

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Ta thy khong cch gia cc chn footprint ca linh kin =100mils. Nn la ch System Settings nh sau:

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Sau to chn linh kin hon chnh:

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Cui cng khi chn s chn ph hp cho tt c cc linh kin chng ta s c c hnh sau:

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Khi chng ta c c s nh trn th c c mt mch in ph hp chng ta cn c nhng nh dng cho mch in ca mnh: System Settings:

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nh dng s lp ca mch in:

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Tip theo chng ta s nh dng c ca ng dy i trong mch:

Chn ng dy rng: min=0.8mm, max=0.9mm

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Sau khi nh dng xong chng ta tin hnh sp xp li linh kin sao cho hp l sau tin hnh i dy. Trong Orcad c ch cho php i dy t ng, chng ta cng c th i dy bng tay tuy vo phc tp v tnh thm m ca ngi thit k. mch ny chng em thc hin i dy bng tay. Chn Add/Edit route Mode trn thanh cng c.:

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Sau qua trnh i dy v chnh sa chng ta thu c mt mch thit k hon chnh, t mch in ny chng ta c th t tay to ra mt sn phm in t cho ring mnh t s nguyn l ban u. Sau y l mch in hon chnh:

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Kt qu: u im: Mch in hon thnh kh nh gn v p. Linh kin xp kh hp l nn ng mch ni cc linh kin kh ngn.Tn hiu truyn t nhiu. Hn ch: cn i 2 dy nh lp top. Tnh thc t ca mch: Dng trang tr loa vi hiu ng nhp nhy theo m nhc kh p mt. Ti liu tham kho: Gio trnh thit k mch in t (Nh xut bn gio dc) Ebook: Hng dn s dng Orcad.

http://www.alldatasheet.comhttp://www.google.com.vn

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