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i C H U B IE N : PTS D K IM B A N G / A / LY THUYET & UNG DUNG r \ / i 1010101010101010100101010101 01 O lo I M N H A m J A T \ B A N LA O D O N G / X A w H r " — M ' PTS DO KIM BANG Bien soan k y m Z7 nr g f m s o □ mJ Ky □ B< i i: ys; i iiA i K’j fljS M 1EUKG TAM HQC U f NHA XUAT BAN LAO DONG - XA HOI ■ HA NOI - 2004 ■ -1 m LQ1 H B & I Ngay nay, ky thuat digital dUOc ap dung rong rai nhieu ITnh virc Cac mach digital dude dira vao sirdung hang loat cac san pham dien tif, nhi/ cac thiet bi vien thong, may ti'nh, ti_r dong hoa, cac choi co mach dien tCr, cac he thong nghe nhin, gia dung, dung cu luting, dung cu y te va quan sir, cac tur dien dien tCr_ Sach Ky thuat digital - ly thuyet va Crng dung gidi thieu nhCrng kien thud co ban ve ky thuat digital va mot so irng dung doi song Be tiep thu cac kien thud de cap cuon sach nay, ban doc can co nhCrng kien thud thong ve toan va ve mach dien tir Ky thuat digital dude nghien ciru trutic hoac nghien cuti song song v i mon hoc dien tir co ban vi cac kien thud ve linh kien ti'ch cifc rdi rac khong phai la dieu kien doi hoi trutic het Co the noi, cuon sach la ngirdi ban dong hanh cua cac ban ham thich dien ti!r digital, cua cac cong nhan nganh dien tu” - vien thong va may ti'nh cGng nhif cua cac cong nhan lanh nghe thuoc cac ITnh vu t co lien quan den cac mach dien tu1digital Cuon sach dirpc xem nhir la tai lieu tham khao hCru dung vi ti'nh thut dung va de hieu cua no doi vdi cac sinh vien cao dang va dai hoc nganh dien tCr vien thong va may ti'nh Sach Ky thuat digital - ly thuyet va u"ng dung co 11 chirong Chi/ong khai quat ve cac he thong so nhi phan, bat phan va thap luc phan, moi lien quan giCra cac he thong vdi he thong so thap phan, chi/Ong cGng gidi thieu tong quan cac ma diroc sCr dung ITnh vi/c vien thong va may tfnh Chutfng gidi thieu ve dai so logic, phan tich va tong hop mach logic, cac djnh ly De Morgan, cac phifOng phap toi gian mach bang bang Karnaugh, bang cac dinh ly va dinh luat cua dai so logic Chi/dng gidi thieu cac mach xir ly so lieu, de cap den cac bo ghep kenh, phan kenh, cac bo giai ma, ma hoa, bo tao va kiem tra bit chan le Noi dung Chi/ong noi ve phep cong, phep trif so hoc, cac phep bu 1, bu va cac bo niTa cong va cong day du, de tirdo, ta hieu di/Oc can ke cac bo cong va bo trir ChiTOng gidi thieu cac ho IC TTL va CMOS, noi dung de cap phan giup ta co cac kien th u t co ban de sCr dung co hieu qua va phoi ket hop di/oc cac ho IC TTL va CMOS cac mach digital Noi dung cac Chuting , ChiTOng va ChGOng di/oc u'ng dung nhieu cac mach dien tu1 digital thong thuting ChifOng gidi thieu cac loai flip flop RS, RS dong bo tTnh, flip flop D, flip flop JK va flip flop JK Master-Slave; ngoai ra, gidi thieu trigo Schmitt, loai trigo co dac ti'nh quan trong, dude su' dung de tao nen cac xung nhip; Chudng cung gidi thieu cac loai mach dao dong, mach tao xung nhip Noi dung ChUdng thirc chat la cac u’ng dung dac ti'nh cua cac flip flop diroc ti'ch hap cac IC de thirc hien cac phep di chuyen so lieu Trong chirong , noi dung diroc de cap la cac loai bo dem va cac Mod dem; tir chirong nay, ta thay diroc cac cau true va cac iru nhiroc diem cua cac loai bo dem Chirong 9, bo nho ban dan va chirong 10, chuyen doi A/D va chuyen doi D/A, hai chirong gidi thieu ve nhCrng nguyen ly cau tao co ban va cac dac ti'nh cua cac bo nho ban dan, cac bo chuyen doi A/D va chuyen doi D/A, giup ta co the Crng dung cac bo kien cac mach dien tir digital Chirong 11 dira mot so mach Crng dung ky thuat digital, nhir dung cu dem tan, do rong xung va dong ho digital Co the xem chirong 11 nhir la mot so bai tap Ion, Crng dung ky thuat digital, tir do, ta co the van dung ky thuat digital vao cac Crng dung khac doi song hang Voi dung y cuon sach Ky thuat digital - ly thuyet va Crng dung diroc viet de cap rong rai kien thCrc ve digital, voi cach trinh bay de hieu, co nhieu vi du, nhieu bai tap va loi giai Tac gia rat mong cuon sach diroc dong dao cac cong nhan lanh nghe cung nhir cac sinh vien cao d in g va dai hoc nganh dien tir - vien thong va may ti'nh, cac ban yeu thi'ch ky thuat dien tir digital rut diroc nhCrng dieu bo ich tu” cuon sach Trong qua trinh bien soan va in an, cuon sach khong the tranh khoi nhCrng thieu sot Chung toi rat mong ban doc thong cam va gop y xay diing, de Ian tai ban, cuon sach diroc hoan thien hon Chung toi xin gCri toi Ban Bien tap Nha Xuat ban Lao dong - Xa hoi loi cam on chan ve sir giup qui bau cua Qui Ban, de cuon sach s m dGOc m§t ban doc DO KIM BANG CHUONG HE THONG SO VA M A ■ Hoc xong chuang nay, hoc vien co kha nang: □ Hieu dwoc cac he dem thap phan, nhi phan, bat phan va thap luc phan □ Chuyen doi d'uoc cac so tit he thap phan sang cac he nhi phan, bat phan va thap luc phan va ngwoc lai □ Tinh d'L/oc cac gia tri cua cac so phan nguyen va phan phan tit cac he nhi phan, bat phan va thap luc phan sang cac so tuong ditong cua he thap phan va ngitdc lai □ Hieu diroc cac cau true mot so ma thong thudng dung ky thuat digital TONG QUAN Khi noi den so dem, moi ngirdi deu nghT den he thap phan v i 10 so: 0, 1,2, 3, 4, 5, , 7, , May vi tinh hien dai khong xir ly so thap phan Thay vao la he thong so nhi phan sir dung so: va Nhi/ng sir dung so nhi phan, muon the hien mot so thap phan co tri so tirong doi Ion bang so nhi phan thi so nhi phan kha dai Do do, ngirdi ta thirdng sir dung cac so bat phan va thap luc phan de rut ngan chuoi so nhi phan Chirong trinh bay cac he nhi phan, bat phan va thap luc phan v i muc di'ch khong chi dem diroc cac so theo cac he dem tren day ma nghien ciru each chuyen doi tir he dem thap phan sang cac he dem nhi phan, bat phan va thap luc phan va ngiroc lai Chu’Ong cung de cap den cac ma nhi phan thirdng diroc su' dung cac he thong digital 1.1 SO NHj PHAN Cac may vi ti'nh va cac he thong digital deu dira tren co so hoat dong nhi phan (2 trang thai) Vi du, khoa chuyen mach Hinh 1.1a co the diroc dong lai hoac mo Do do, khoa chuyen mach la mot vi du ve thiet bi nhi phan don gian nhat Tranzito cac mach dien tir dung cac he thong va cac may tinh digital diroc thiet ke de hoat dong tirong hop v i he thong nhi phan, la hien tirong ngirng dan hoac dan bao hoa cua tranzito Ket qua la ngo cua mach tranzito co mot hai trang thai mire dien ap cao hoac mire dien ap thap Khi quan sat tin hieu digital tren may hien song thay dien ap hoac m ut thap hoac mire cao Cac tin hieu digital thay doi mire dien ap may vi ti'nh hoat dong, cac dien ap xuat hien nhir la cac xung (Hinh1.1b) 5V 5V +v o CLK CLK -C> CLK Q CLR a) Ky hieu FF JK CLR — ©— b) FF JK xac lap va c) FFJK xac lap va phuc hoi mtic H phuc hoi O mtic L Hinh 6.14: Flip flop JK 6.7 FLIP FLOP JK MASTER-SLAVE Hinh 6.15 la sd nguyen ly ve cau true cua flip flop JK Master-Slave Flip flop JK Master-Slave gom flip flop: flip flop Master va flip flop Slave, flip flop JK Master-Slave hoat dong nhu sau: flip flop Master chuyen trang thai b§ng sudn duong xung nhip va flip flop Slave chuyen trang thai bang sudn am xung nhip Do do, flip flop Master dap ting vdi ngd vao J va K cua no trudc so vdi flip flop Slave Neu J = va K = 0, flip flop Master xac lap sudn di/Cng xung nhip tdi ngd vao cua CLK Ngd Q = se dieu khien ngd vao J cua flip flop Slave, nen sudn am xung nhip xuat hien, flip flop Slave xac lap, chep lai hoat dong cua flip flop Master Hinh 6.15: Flip flop Master-Slave Khi J = va K = 1, flip flop Master phuc hoi nhd sudn dudng xung nhip tac dong Ngd Q = cua flip flop Master di den ngd vao K cua flip flop Slave Do do, sudn am xung nhip tdi ngd vao CLK cua flip flop Slave lam cho flip flop phuc hoi Lai mot Ian nu’a, flip flop Slave chep so lieu cua flip flop Master 168 Neu co hai ngo vao J va K cua Flip flop Master deu^d muc 1, ngo Q se chuyen trang thai bu sUo'n duong xung nhip xuat hien d ngo vao CLK cua flip flop Master Khong can quan tam la flip flop Master da chuyen trang thai nao chi biet la f|jp f|0p Slave chep giong het hoat dong cua flip flop Master, flip flop Slave cung phuc hoi (Reset) Hinh 6.16a la ky hieu cua flip flop J K Master-Slave Flip flop co chu’c nang Preset va Clear Vong tron nhd d ngo vao CLK nhac ta nho la ngo chuyen trang thai sudn am xung nhip xuat hien d ngd vao CLK Flip flop JK MasterSlave hay ducfc dung cac bo dem IC 54/74 LS76 cd mot cap flip flop JK Master-Slave, dupe dung rong rai ky thuat mach digital Chan IC 54/74LS76 va bang su that duoc trinh bay tren Hinh 6.16b va c Output Input Tai thai diem tn Tai thai diet a) Ky hieu cua Flip Flop JK chu-ta J K Qn+1 0 Qn 1 1 Qn c) Dang su th a t b) Ky hieu logic va chan cua IC 54/74L S 76 Hinh 6.16: Flip flop JK Master-Slave 6.8 TRI-GO SCHMITT Tri-go Schmitt la mot mach dien tir dupe dung de phat hien xem dien ap cd vupt qua mu’c tham chieu hay khong Mach tri-go Schmitt cd hai trang thai on dinh va dac biet dupe sir dung nhu la bo dieu chinh tin hieu Cd xung hinh sin, xung tam giac, hoac xung chu ky cho trudc nao d ngd vao, tri-go Schmitt se tao xung hinh chu nhat d ngd ra, cd sudn trudc va sudn sau th in g dirng, nhir yeu cau ve xung doi vdi cac mach dien tir so VOUT VO UT (V) M i'ic H 3.4 MucL i ' a) Hinh 17: Dac tinh ddng thai chuyen mu'c cua tri-gd Schmitt Hinh 6.18: Invectd tri-go’ Schmitt a) Ky hieu logic b) Dac tinh chuyen mu'c 169 Hinh 6.17 bieu thi chCrc nang di chuyen (VOUT doi v6i VIN) cua tri-gd Schmitt Gia tri VIN tao d ngo budc nhay tir mu’c L len mu’c H, duoc goi la dien ap ngudng dirong VT+, gia tri VIN tao ngo budc nhay tir mu'c H xuong mu’c L du’Oc goi la dien ap ngudng am VT Dien ap ngo hoac mu’c H hoac mu’c L Khi ngo d mu’c L, can tang dien ap d ngo vao Idn hon mot chut so vdi VT+ de cd the chuyen mu’c Sau do, dien ap d ngd dupe chuyen trang thai tu’ mu’c L len mu’c H va tri trang thai cho den nao dien ap ngd vao giam nho hon gia tri VT_ mot chut, do, ngd se chuyen trang thai tir mu’c H xuong mu’c L Cac mui ten va dudng dut net bieu thi cac dong thai chuyen mu’c Sir phan biet giua hai dien ap ngirdng dupe biet nhir la dudng tre Cd the loai bo hien tupng trd thiet ke mach, nhirng mot lirpng nho cua hien tirpng tre la can thiet, vi no dam bao cho dong thai chuyen mu’c nhanh tren mot giai rong cua nhiet Tre cung cd the la mot dac ti'nh cd Ipi Vi du, tre cd the du’Oc sir dung de loai tru" nhieu cac Crng dung nhat dinh IC 7414 cd mach Invecto dung tri-go Schmitt, dang DIP Hinh 6.18a la ky hieu logic chuan cua Invecto dung tri-go Schmitt IC 7414 Trong Hinh 6.18b, dien ap ngd vao virpt qua mu’c 1,7V, dien ap ngd se chuyen trang thai xuong mu’c L Khi dien ap ngo vao xuong nho hon 0,9V, dien ap ngd se chuyen trang thai len mu’c H Dong thai chuyen mu’c dupe cac mGi ten va cac dirdng dut net bieu thi Hinh 6.19: Cac dang xung ngd vao ngo cua tri-go Schmitt Hinh 6.19 chi dang xung ngd vao va ngd cua trigo Schmitt Hinh mo ta tin hieu d ngd vao va ngd cua co’ng dao sir dung trigo Schmitt Trigo Schmitt da thay doi dang xung tir dang song hinh sin d ngd vao dang xung chu nhat cd sudn trirdc va sudn sau th in g dirng Hoat dong cua trigo Schmitt cung tirong tu doi vdi cac dang xung ngd vao la cac xung cd chu ky, xung ngd cung v in la xung chCr nhat 6.9 CAC DANG XUNG NHIP He thong xung nhip cung cap dang xung chu ky dung lam tin hieu dong bo Xung vuong nhu Hinh 6.20a la loai xung dien hinh dung he thong 170 digital That khong can xung nhip co dang that doi xirng nhi/ chi tren Hir>h 6.20a, ma co the la mot chudi xung di/dng (hoac am) nhu” chi tren Hinh 6.20b, dang xung la xung vuong khong doi xirng jThgi gian chu ky xung nhip CTi gian chu ky xung nhip Hinh : Cac dang xung nhip ly tifcng Hinh 6.20 Can chu y rang xung nhip dirpc xac dinh la khoang thdi gian cd ban, khoang qua trinh hoat dong logic phai du’Oc dien Khoang thdi gian cd ban di/dc dinh nghTa la thdi gian cua mot chu ky xung nhip Nhi/vay, tat ca cac phan tCf logic, flip flop , cac cong v.v phai hoan chut nang cua chung khoang thdi gian nhd hon thdi gian cua mot chu ky xung nhip Dang xung nhip ve tren true thdi gian nhi/ d Hinh 6.21- ThCr nhat, xung nhip phai co mu’c logic tuyet doi on dinh Khi xung nhip d trang thai 1, mu’c logic phai tri dung d dien ap +5V, nhi/ chi tren true thdi gian giCra diem a va b xung nhip d trang thai 0, mu’c phai khcng thay ddi va bang OV nhi/ chi giCra diem b va c Tren thirc te, ti'nh A 10 100 N Ik \ ^ i N \ 10 k 100k f (Hz) Hinh 6.23: Mach dinh thdi dung IC 555 Vi du: Xac dinh tan so dao dong cua bo dinh thdi dung IC 555, neu RA= Rb = k Q va C = 1000 pF Ldi giai: Dung cac he thu’c tren, ta co: 1,44 F= 480 kHz [1000 + 2(1000)] 10" 174 6.12 DAO DONG DON ON DUNG IC DjNH THCJl 555 Chi vdi si/ thay doi nho, bo dinh thdi trinh bay phan 6.10 chuyen bo dao dong cd mot trang thai on dinh (don on) Loai mach di/pc dung rong rai ky thuat Hoat dong cua bo dinh thdi la d ngd vao nhan du’Oc mot xung tac dong, no chuyen sang trang thai gia on dinh, no tri trang thai nijy mot khoang thdi gian t du’Oc dinh tri/dc Sau do, mach trd lai trang thai on dinh cua no cho den lai nhan du’Oc mot xung tac dong mdi VI mach chi co mot trang thai on dinh nen du’Oc goi la mach don on TRIGGER TRIGGER Q Ob) Dang song a) Ky hieu logic Hinh 6.24: Mach don on Hinh 6.24a la ky hieu logic tieu chuan_cua mach don on Ngd vao du’Oc ky hieu tri-go, ngd ky hieu Q va phan bu la Q Thirdng thi ngd Q co trang thai mach trang thai on dinh Hinh 6.24b gidi thieu dang xung cua ngd vao tri-go va ngd Q Trong tri/dng hpp nay, mach du’Oc tac donq vdi sirdn am cua xung tri-go va ngd cd mu’c mach phuc hoi ve trang thai on dinh Mot du’Oc tac dong, Q len mu’c va tri d mu’c khoang thdi gian xac dinh tri/dc t va chuyen ve trang thai on dinh cua no cho den sirdn am xung tri-go khac xuat hien d ngd vao Hinh 6.25a la mach don on Trong trang thai on dinh, tu dinh thdi C phong dien hoan toan qua tranzito ben cua IC, noi tu C vdi chan 7, luc do, ngd d chan cd dien ap bang (tiep dat) + Vcc + 5V den + 15V RESET RA RL 555 Tai "dong mach' Ngo Gnd Vcc Dis Out Thr Rst Ctl f RL ~ >7 / / / / 01 / / / >/ // 1ms •001 100 us a) Mach dan on lom ' / XJ ; / / Phong dien NgUcnig f?ien ap dieu khiet, O lu F Tai "cat mach1 - 10 -rt* Trg t r ig I er- 100 / 100 ms 10 ms 1s 10 s b) Thai gian tre t = 1.1RA x C Hinh 6.25: Mach don on dung IC 555 175 100: Xung am cua ngo vao tri-go (chan 2) lam cho mach chuyen trang thai gia on dinh Luc do, ngo chan len mu’c va tranzito phong dien chan se chuyen trang thai lam cho ngo co mu’c 0, nhu vay, luc tu dinh thdi C blit dau nap dien cho den dat mu’c + Vcc Khi dien ap tu C dat t6i 2/3 dien ap +Vcc, mach se tro ve trang thai on dinh, tranzito phong dien, dong mach trd lai va tu C phong dien xuong dat, ngo se tro lai mu’c (tiep dat), mach tri trang thai cho den mot xung khac den ngo vao tri-go Ngo cua bo dao dong don on co the du’Oc xem la cac xung duong va rong xung duoc xac dinh nhu sau: t = 1,1 (Ra x C) So cho tren Hinh 6.25b duoc su" dung de tinh nhanh cac gia tri RAva C can co cac rong xung khac Co the kiem tra xem gia tri dat dupe bai tap 6.14 nhu sau: RA nam tren dudng 10 kQ tuong ting vdi dien dung C = 0,1 i^Fco rong xung vao khoang ms./ 176 CAU HOI VA BAI TAP 6.1 Neu dac diem cua flip flop Diem khac co ban giura flip flop va mach logic to hpp la gi? 6.2 Hay so sanh iru nhi/pc diem cua cac loai flip flop RS va JK 6.3 Neu cac diem giong va khac giCra cac flip flop RS MasterSlave va JK Master-Slave 6.4 Giai thi'ch hoat dong cua flip flop D 6.5 Giai thi'ch hoat dong cua flip flop JK Master-Slave 6.6 Gia du rang xung nhip co dang xung vuong, thdi gian tre khong dang ke va trang thai ban dau cua flip flop a mu’c Hay ve dang xung tai diem Q2 nhir tren mach dien Hinh 6.26 +5V J1 Q1 -CJ>CLK JTTL CLK K1 J2 02 r C (> CLK K2 Hinh 6.26 6.7* Ve lai f!ip_flop_sir dung cong NAND nhir tren Hinh 6.4a va_gan cac mu’c logic vao cac chan S = R = Lap lai doi vdi cac trirdng hpp: S = R = 1; S = 1, R = 0; va S = 1, R =0 6.8* Cac dang xung cho tren Hinh 6.27 dieu khien flip flop RS dong bo tinh nhir tren Hinh 6.5 Xung nhip chuyen tir mu’c L len mu’c H tai cac thdi diem A, C, E va G Neu Q mu’c logic L trirdc thdi diem A, Hoi: a) Tai thdi diem nao Q len mu’c H? b) Khi nao Q phuc hoi ve 0? CLK -TLnLTLTU A B C P E F G H n Hinh 6.27 6.9* Hinh 6.28 (Hinh 8.12) cho biet cac dang xung ngd vao cua R S va CLK du’Oc dat vao flip flop RS dong bo tinh Hay giai thi'ch dang xung ngd Q "!77 t1 t2 Thaigian ■ CLK O1 01- Q t3 t4 t5 t6 4- I I t7 t3 I I II I I i i JL -H i i n o- Hinh 6.28 6.10* Cd flip flop JK Master-Slave nhir tren Hinh 6.29 co cac ngo vao J va K diroc noi den +Vcc va chudi xung vuong dirpc dat vao ngo vao xung nhip CLK Hay mo ta dang xung ngo Q +Vcc J CLK- Q c> K- Q Hinh 6.29 a BAI TAP 6.11 Trinh bay nguyen tac hoat dong cua cac ngo vao phu (Clear, Preset) cua cac flip flop 6.12 Ti'nh gia tri cua cac dien trd R „ R2 va tu dien C tren Hinh 6.23 de ngo co cac dao dong vdi cac tan so: a) 100 Hz b) 500 kHz 6.13* Tinh rong xung ngd doi vdi bo djnh thdi cho tren Hinh 6.25 vdi cac dir lieu sau: Ra = 10 kQ C = 0,1 pF 6.14* Xac dinh gia tri cua C can thiet de chuyen doi rong xung bai tap 6.13 10 ms 6.15* Xac dinh tan so dao dong va cac gia tri t1 va t2 cua bo dinh thdi sir dung IC 555 nhir tren Hinh 6.23 vdi cac gia tri nhir sau: Ra = 5000 Q, Rb = 7500Q va C = 1500 pF 178