Di6t binh thuang da xem xet a ml,lc 2.2.1 la.m vi¢c theo d~c tuy~n Von- .Ampe (hlnh 2.19) Ilng v6i nhanb thu~n a goc vuOng I. Di6t thOng thuang
kh6ng.duqc phep Hun vi~c trong vung sat chl dQ danh thung (rung khuyu 4).
'.
Ung -Uz o
2 Fbanap
ng\IQC 3
,
~
0)
1 Fbanap
thu~
b)
Di6t Zener la lo~i di6t d~c bi~t, lam vi~c duqc b vung danh thung voi di~n ap pha.n ql'C nguqc.
D~c tuyln Von-Ampe clla di6t Zener nhu tren hlnh 2.3.6. Khi pMn ap thu4n. di6t Zener lam vi¢c nhu di6t thOng thOOng (do~
1). Khi pMn ap nguqc, di6t Zener khOng dAn di~n rna cbi c6 dong ro khOng dang kt'! (do(l!12). Khi di¢n
~p nguqc vuQ't qua gicri h~n d~nh
thung - Uz thl dong di~n qua di6t Zener tang V9t. nhung di¢n ap -Uz glin nhu giu nguyen (do~n 3).
Tinh cha't nay cua di6t Zener duqc Ung dl:mg la.m pMn tu 6n dinh
diÂn ap - ã-di6t 6n ap (diÂn ap 6n djnh 1. U,).
Hi"h 2.36 .. D4c tuye;/ Von-Ampe (a) vd kf hifU (b) cuo diat Zeller
Hai thOng s6 quan trQng cua di6t Zener la di¢n ap 6n ap Uz va cOn.g suilt tieu tan tren di6t Zener Pz. Tu 1,Jz va Pz c6 th~ tfnb dong nguqc qlC d~i cbo phep qua di6t Zener 1.:
1" =--..Z.... P
Zmox U , (2.9)
R,
' -_ _ -<-_-i> ,
Hinh 2.37: Sd dd tht}ng thll&lIg I1Inc
diat Zener
Di6t Zener duqc mac trong m~ch 6n ap thOng thuang nhu hlnb 2.37.
Ngu6n ca'p di¢n ~p dn co di¢n ap Ian han di¢n ap 6n ap (Ung > U1)
Vi lai mac song song voi di6t Zener va cimg c6 di¢n ap Uz nen dong qua
Ro giu khOng dOi (coi ngu6n c6 Rng =:: 0).
Unl - Uz
lRo= =II+Iz""'invar
R,
Tit d6, khi dong tai tang (giam) bac nhieu thi dong qua di6t Zener giilm (tang) b!y nhieu. N6i cach kM.c, gia s6 biln thien cua dbng di~n tren tai va tren di6t Zener IUOn bAng nhau vai huang biln thien nguqc chi~u nhau.
b) Di6t pMt Quang
Di6t pMt Quang con gQi Ia den LED (Light - Emitting - Diode). Di6t pMt Quang cilng c6 ca'u truc P-N va d~c tjnh Von-Ampe tuang tl! nhu di6~ thOng thuang nhlffig nguOng din di~n khi phAn ap thu~n cac han (1,6V + 3,OV), chiu di~n ap nguqc kern han (3V + i5V) va khi dan di~n thea chi~u thu~n thi pMt sang. Mau anh sang phl,l thu¢c vAa v~t li~u chI! t~a (bang 2.2).
Bang 2 2
V~t H+u chi tlllo LED Gallium - Arsenid Gallium - Arsenid Phosphid
Gallium - Phosphid Sillizium - Karbid
Gallium - Nitrit D~ng pb6 bitn cua LED va. kf hi~u
LED tren sa d6 di~n
duqc bi~u thi nhu tren blnh 2.38.
LED duqc sir dl,lng r¢ng rai trang nhi~u
Hnh VJ!c Quang bao do
th~ tich nhb, cOng sua:t tieu tan tha'p, thfch.
hqp vai cac m~ch
logic. LED co th~ sir dl,lng d~ Mo hi~u
tril-ng thai lam vi~c cua m(H m~ch hay baa m¢t hnh ki~n bi hong.
Tu6i thQ cua LED cao
(~ 10' gia).
Mo" BlIi:Ic 56ng l. fJ,lm)
H6ng ngoljli 0,91
Db 0,65
Xanh Iii. cAy 0,56
Xanh da lrai 0,49
Tfm 0,40
.)
b)
Hi"" 2.38; Dgng pM bie1l clio LED (0) va kJ hi~1I LED (b)
tren sdM di!n
Khi sir dl,lng LED, cAn luu y di~n cip mQt chil!u d~.t l~n LED thea chi~u thu~n khOng n~n vm;Jt qua di~n ap nguang (::::: 3V + 5V) va dong di~n khoang
IO rnA + 20 rnA. Do v~y, thuang c6 m~t di¢n trb mAc n6i ti€p vai LED:
R= Unl: -ULEO
IillD
trong do: Ung - di¢n ,ap ngu6n nuOi ;
Vfd~2.1:
U LED - di¢n lip ngu6ng cua LED;
I LED - dong di¢.n qua LED.
(2.10)
M~t LED c6 nguong di¢n ap 3V va dong 10 rnA mitc vilO ngu6n mQt chi~u 12V thi di¢n trb dn n6i ti€p vai LED (hlnh 2. 39) lit:
R= Ung-ULED =12-3=9000
lLE!) 0,01
Thl!c t€, khOng c6 san di¢n trb 9000 nen ta chQn di¢n tro 10000 = 1 kn. COng 5U&'t di¢n tro la:
P = RI' = 900.(0,01)' = 0,09W
ChQn lo~i di¢n tro 1 kn c6 cOng 5U&'t ~ W =0,125W . Vi dI,l2.2:
<12V
:: R=IKn
- -
Hmh 2.39: LED ntJl vdo ngu&n 12V
M¢t LED c6 ngu6ng di¢n ap 3V va dong 20 rnA mAc vao ngu6n xoay
chi~u 220V thl phiti mAc th€ nlo?
Di¢n tro C4D mAc D6i ti€p la:
R=220-3 =58500 0,02 •
•
Vl khOng co siin di¢n trb nay, nen ta chQn di¢'n trb 6,8 kO vcri cOng suit:
P = 5850 x 0,02' = 2,34W .... chQn P = 3W (hlnh 2.40a)
Vi di?n Ap danh thung cua LED tMp (3V , + 15V) n~n IJ nua chu kl pMn ap nguQ'c. LED se bi danh thung. Do v~y, cain mAc th~m m¢t di6t silicon song song nguQ'c vai LED (hlnh 2.40b). Nhb' d6. di¢n ap nguQ'c dl)t l~n LED se bAng di¢n tip rai tren di6t b nira chu ki phan ap nguQ'c (It: 0,5V). Di6t dn chiu dong
220 V ~ ° 033A.
6800n '
Sir d\1D8 LED
~ng mfch xoay
cbi~u 220V. c6 thi tham kUo mOJ.Ch 6 hlnh 2.4Oc.
MQt chu Y kh8c
khi sir d1,lng LED Ill.: CalOI cua LED thuang b chilD ugAn
ho~c b phia vo bj
cat XeD (bloh 2.38a) vA di¢n C1:rc cua cal6t thuang
Ian han di~n qrc
cUB a06t.
LED con duqc dung trong cae hi~n
th! s6 va chii' qua cae blob dang LED
d~ng chilm hay dl.1ng g~ch dai. Hloh 2 . .41 Ill. hai dl.1ng s6 dan va s6 kep dung bay thanh LED bieu
nii m¢t con s6.
c) Tranzito truang
-220V -220V
R =6,8Kn =R=6,8Kn
o
f: 50Hz
.) b) 0)
Hlnh 2.40: LED 11m ~do IIgu611 220V
10 9 8 7 6
f~b •
.~o I)cdJ 0
2 3 4 5
. . .
. . .
Hill" 2.41: LED ooy thanh
Tranzilo thuang dB: tclub bay 6 ml,le 2.2.2 la pMn IU dUQ'c di~u khi~n
bang dong di¢n vA din di¢n bing d. hai iOl.1i phdn tiI mang di¢n : di¢n tiI vA 16 trOng. Tranzito truOng. con gQi 18 tranzito hi¢u dng truang hay FET (Field - Effect Transistor) la phin tir di~u khi~n bAng di¢n ap. Tranzito hi¢u ilng truong lam vi¢c tren co sa dong di¢n qua lap ban dan mong se bl bil!'n d6i nba rae dOng cua m¢t di¢n truang vu6ng goc voi lop ban dAn d6.
FET dAn di¢n chi bAng mOt IO'.li phiin tir mang di¢n (ho~c di¢n ti'r, ho~c 10 tr6ng) nen con c6 ten la tranzito dan qrc . .
PET co ba qrc la : qrc mang D (Drain), qrc ngu6n S (Source) vA cllc dra G (Gate). Lo'.li FET dung trong bO t.d:n s6 c6 bOn cl!c. vi cO hai cl!c dra rieng bi¢t (Gl va G2 ).
PET chia ra HUn hai lo~i:
- LO'.li c6 cl!c dra G 18. lap til!'p xuc P-N (JPET : Junction Field - Effect Transistor).
-Lo~i co qrc dra cach Ii (MOSFET : Metal Oxyde Semiconductor Field - Effect Transistor).
JFET
Hinh 2.42 trinh bay nguyen If cA'u t~o va ki hi~u cua IFET kenh N (hlnh 2.42a, b) va kenh P (hlnh 2.42c. d). Giii'a c.I!c nguOn S va. qrc mang D c6 vang ban dan t~o thanh cllc cil'a G. Do d6, tren duong di giii'a cac cllc S-vs. D co mQt vung tiep giap P-N t~o boi kenh dAn va lOp ban dAn cllc cua.
D
D
G G
G
s
.) b) 0)
Hl"h 2.42: Nguyill/j nfu tfJO va kjhifU c,w FEr
xet JFET kenh N theD so do tren hlnh 2.43. Thy thea dj~n a p giii'a qrc G va cllc S Am nhi~u hay it rna vung chuy~n tie'p rQng hay
h~p va dang ID til D sang S nha hay Ibn.
JFET c6 tra khang til
vai MO de'n vai chl:Ic MO.
MOSFET
D~ tllng tra kh'ng vAo cao han (de'n hllng ngAn MO), ngubi ta c8l ti!n PET Dha dung C\rc cua cach di~D
c6 nguyen If clu t~o nhu tren hlnh 2.44. eve G cach
s
NiAll 2.43: JFEr U"h N
D
G
s
d)
R,
ly voi thanb Mn dan P hoi Wp oxyt silic each di~n. Thanh bAn dAn lOQ.i P (cung co the III lo~i N khi S, D lo~i Pl.
Kiml~
o.Jr :::::f
Thw>h ,",p Kenh d!q N s s
a) b) c)
Hill" 2.44: Nguyln Jj cau t~ (a) va ki hifu (b, c) cua MOSFE[
Khi d~t vao qrc G m¢t di~n ap so vd'i c\I'c S thi trong thanh ban dAn P hlob thilnh mQt kenh dAn l0i1-i N thOng gili'a CI1C S va C1:I'C D. Kenh nay rQng hay h~p
HI. tuy dien Ap dua vao Cl,IC G Ion bay nba.
Tranzito tnIang c6 hai c,!c dla tach biet dugc ki hieu nhu blob 2.44c.
cae traozito trU'oog c6 mQt s6 d~c diem:
- Dien trb vao rlit I6n (vai MO dl!'n hang ngao MO).
-Tl;LpAm Dho.
- S", bi'!n dOi ella dong di~n thea nhi~t dQ ngu<;,c vCti traozita thuc:mg : nhiet dQ ta.ng thi 51! thOng dAn 1,i giam.
Tranzito truoog dugc lhlg dl,lDg de khu.!ch d,i; t~o dao dQng, ph6i hgp trb khAng, khoa dien u.'r.v.v .. (Tog dl.lng da d,ng eoa traozito truang 130 nha d,!a v~o cac d~c diem da neu va cac U'U diem sau:
- Tranzito truang MOSFET 18: phcin tU di~u khien bing di~n ap. trong khi cac tranzito thuang (m1,lc 2.2.2) Ii phd.n tu di~u khien bang dong di~n.
- Tranzito truang MOSFET c6 tin 56 d6ng cAt rlit cao (t6i v30i trilm kHz)
m~c diI kha nling chiu tai v~ dong di~n va di~n ap kern han tranzito thuang.
Voi uu thl! nay. n6 duqc dung trong cac bQ ngu6n xung cua may tinh PC.
- T6n bao cOng su:!t khi lam vi~c nhc Khi sir d1,lng tranzito truang dn lUll y:
- Tranzito truang nh~y cam vai truong tinh di~n ngoai. Di~u n~y dn d~c
bi¢t hru y khi dung MOSFET.
.,
,"
- Til!p da't mb han khi han, tbaa tranzito truang ;
- NgAn ml.lch cae chan tranzito truang khi chua sir dIJng ; - Khbng thaD, lap tranzito tcuang khi co ngu6n ;
- Khbng thit tin hi¢u khi khOng c6 ngu6n.
Vi d~ 2,3:
Ml.lch khu&h dl.li am '!n dung FET (hinh 2.45)
+12V
R, FET,D Ie,
Tranzito tmong kenh N. C l I II .01
Tin hi~u (xoay chi~.u) vlw ~.Olll-, ~--,G'+l-"sr---' qua tJ,l CJ • TI,I Cj Ht tl,l each Ii hI R2 R3 C3
m(:lt chieu giUa FET va u. -- 2M 1.5Kt ~~ 20j.J.
nguOn tin hi¢u vao. Khi c6 tin hi~u (xoay chieu) vao, ngan m,!-ch qua C •• toj qrc 0
thi tren c1!c mang D co liD HlRh 2.45: Mqch thuech d9i dung Fer .
hi¢u XQay chieu, !ify ra qua tl,l ~. 11:1 C) nhAm ogAn ml.lch di¢n trO R3 ve xoay chieu nhAm dam bao tro khang qlC S so v6i OV Ia nho. DAy l8. m~ch khu&h dl.li qlC S chung.
Vi d~ 2.4 :
Khoa di~n til dung FET (hinh 2.46)
Khi dien lip di~ukhieD Udk = Ua, = 0 'hi PET 'hOng bio hoA.
tai coi nbu dUQ'C cap di~n ~y dia (U, ~ U .. ). Khi U" am PET tho!
(,huang -4V + -5V) thl 'ai coj nhu bi ngit di~n (U, ~ 0),
+ D
, ... ~
R,
, .J..:. Cas
~ ,+ ,
•
OR.
"CD:
...
HiM 2.46: KhOO tlj~1i til dtJng Fer
Ois lei R, ::t! IMQ. R2 ChQD sao cho Ian ban nhi~u Ros luc thOng bao boa.
Do thOng tranh dugc 51! c6ãmi)t ella di~n dung Cas gWa cqc G va ClJC S nen c6 rn! thai gian khi FET chuyen m(l,ch (VI Cas nl;lp khi Udt < 0 va CI,l'C 0 se hj am trong thai gian Cas ph6ng di¢n), De darn bIIo qrc tiob Udk khong duong m(l,ch co mac them di6t D.
d) Tranzito m"t til!p giap
Transistor mQt til!p giap con gQi Ill. UJT (UniJunction Transistor) co nguyen 19 cllu 1<)0 tcloh bAy 0 blob 2.47.
B, B,
B, B,
N P
E E B, E B, E , ,
N, ,
B, B,
a) b) c)
Hi"" 2.47: Nguyini; cdu tt;lo (a) vd if hi¢u (b, c) eua Uff
UJT c6 ba qrc : hai qrc baw (BI • 8:J) va. mOt qrc pMt (E). Nhu bloh 2.47a, d~ n6i gHl'a hai qrc haw III blin dAn N. qrc pMt E lA ban dAn P. Loq.i UJT kenh N nay c6 kf hi¢u nhu blob 2,47b. N~u dt! Iii ban dAn P, qrc E la ban dan N thi VIT dUQ'c kf hi~u nhu bloh 2.47c. D6 ta UJT ktnh P.
co the coi UJT (hlnh 2.47a) nbu m/?t di6t c6 hal d.fu Ia BI va ~ v6i phAn ap RBI va RBl (bloh 2.48). RBI vlt RBl duqc coi lA di¢n tra d~N til E tm RBI va t6i Rill'
I,
B,
D R~ 3
E +
A U" I, ,
+ , , 2
U, R ..
I, ,
----~---
B, , ,
" u u .... u,
Hill" 2.48: Su dd II/drlg dlldllg CUD m4t un Nu.1t 2.49: lJ4c Iuyi'n Von-Ampe cuo Uff D~t m¢t di~n lip biin thien UE vllo girm hal C\lC E vlt B, thl dbng IE se bi6n thieD. QuaD h¢ U,(I,) thu duqc gQi lA ~ tuy!n Von - Ampe cua UIT (hinh 2.49).
R~ R,
Khiham<)chEBjthi :UA=R .UBB=T)U sa v(ril1= '
8, + Rs, RD, + Rs,
Thuang 11 = 0,45 + 0,75 va 11 cit it ph\J thu¢c vao nhi¢t d¢.
+Ue +Ue
R R, R R,
UIT urr R,
B,
E B, U. E B, C Th
+ U
C R, C R,
.) b)
Khi UE <
T]VRa + UD (v6'i Vb HI. di¢n ap nguong eua lOp til!p giap P-N - eOng la di¢n ap nguong de dIn dong thu~n eua di6t D, thuang kho'ng (O.5V + O.7V)) thi UJT con chua lam vi¢e (khoa).
Qua UlT ehi eo dong ro rA't nha (doan I).
Hlnh 2.50: Mfileh tgo xUlIg rang ella (a) va m(1Ch lIitw kIIj/1I thyrislO (b)
Khi UE > T]UBB + VD ,
VlT ehuy~n sang dA.n di¢n (th6ng) voi d~e di~m IE tang dan trong khi VE titng toi VEmu r6i giam xu6ng
VEmin (do~n 2). a do~n
nay, tr! s6 IE do di¢n tra
m~ch ngoAi quyl!t djnh.
DAy la vfing UlT c6 di¢n tra.m (e6 -I Ul + -2 to).
Nguyen nhan IA di6t D din lAm RR2 vA RBI giam, d"c bi¢t la RBI. Do d6. T] giam vA U A giam, dong IE t4ng.
Khi I, > I, .(hl Uff e6 di¢n lrb' duang nha, elf! 00
(do~n 3).
Transistor mt)t til!p giap.
thuang duge (mg d\lng trong
m~ch t(to xung (ki~u dao d¢ng tfeh thoat) ho~c dfing d! thOng thyristo.
U,
---~~~---;~--
, --
2 ,
, .)
, , , , ---..,-- , ,
tl :
' " , , , ,
, , , , , , , , , , , , , , , ,
, , , ,
, , , ,
, , , ,
, , T
~ ,
l< , ,
o '0
U. , , , , , , , , , , , , , , , , , , , , , , I
b)
o
Hinl! 2.51: GMn dd thbi gia" cua tn(lch tr,wxung hInl! 2.50
Vf d~ 2.5:
M~ch t~o xung rAng cua (xung tam gi.1c) (hloh 2.50),
T~i thai diem to, c~p nguon +USB cho m~ch. TI,l C duqc n~p di~n qua di~n lrb R. Di~n ap UE tAng ditn thea ham mfi (hloh 2.51a) nhlffig UJT vAn b ch€ d¢
khoa chilng DaO UE con nho han UEmax ' Di~n .1p ra Uta tr~n B] nhu tren hlnh 2.51b. Khi t~ C duqc n~p t6'i di~n ap UE.> UEmu (thai dil~m t1) thi UJT thOng.
Gill'a B2 va BJ c6 dong 121 , d6ng thai t~ C ph6ng di~n til E qua BI vlt RJ v6i dong di~n d<.mg ham rnO suy giam va UE giam nhanh. Ditu ra BI c6 di~n ap d .. mg xung nhQD. Khi UE < UErnin (thai di~m t2 ) thi UIr thoa va t1,l C li!i duqc
n~p di~n qua R. Qua tdoh eli' th€ ti€p di~n.
Tiln s6 xung (do d6 chu ky T) phl;l thu¢c R, C. Xung fa Ura -vI! nguyen lac
• co the dung d~ rna thong thyristo nhu sa d6 hloh 2.50b. Vlfn M con l{Li 18 ph6i hqp va ChQD thai diem phiit xung.
~) Diac
Diac la dl,lng Cl,l ban dAn g6m ba l6'p b.1n dAn (hlnh 2.52a) nhu tranzito nhung chi c6 hai qrc. Ki hi~u diac nhu hloh 2.52b.
Diac c6 kha nAng dAn di~n thea cii hai chieu. D~c tuy€n Von-Ampe clla diac nhu hlnh 2.53. D*t tuy€n nay tuang t\l' triac nhlIIlg khOng cAn di.!u khien.
P N p
.) b)
I ... __________ _
ãU, u, u
Hlnh 2.52: Nguyelllj cau tqo (a) Hlnh 2.53: D~c Illyen Von-Ampe cua iliac va ki hj~1J. (b) cua iliac
Khi di~n ap U d*t len diac thee chMu nlLy hay chi~u kia nhc) han gia tli nguang Uo : lUi < IUol thl diac khOng dAn di~n (kholi).
Khi di~n ap d*t Mn diac : lUI~IUolthl diac dAn di~n (thOng). Lllc nay, di~n .1p rai tIen diac nha han ]Uol. DOng qua diac phq. thu¢c m~ch taL Khi dong qua diac (dong tail ]11 < ]Idli thl diac t\l' kho.1.
Vf dl,l 2.6 :
Hinh 2.54 Ia m~eh dung diae dieu khi6n m~t triac.
Qua m~ch VR-Cl va R- C2 • di~n tip xoay ehieu UC2 d~t
len diae. Khi iUC2i bang ho*e C1 Ian han di¢n lip nguang IU(l1
cua diae thi diae thong, t~o dong xung lam triac th6ng, cap di~n eho tiii a ca hai nua diu ky xoay ehieu.
R,
R D, Tn
c,
Hillh 2.54. Mgch dung diac dieu khitn (riac.
Goe ma triac duqe dieu ehinh bai bien tra YR.
cAu H61 CHUONG 2
I. Tfnh chat eua di¢n tra. tl,l di¢n va ell¢n day trang m~eh di¢n m9t ehi6u
(f = 0) va xoay chieu (f"# 0) e6 gi kh<k nhau?
2. Tan s6 dong di¢n co anh huang gl taj tfnh ehA""t eua ba lo~i linh ki¢n thl,!
d~ng?
3. Neu 1u~t mau de dQc cae gia tr~ cua di?n tra va tl,l di¢n?
4. Nell nguyen ly call t~o cua cae Hnh ki~n di¢n tir dch Cl,re : diat, tranzito, thyristo, triac? Neu ten cac cl!C eua chung?
5. So saoh d~e tllyen Von-Ampe eua cae iinh ki¢n di¢o tir tfeh cl!e da: bi€t?
6. Nell di~u ki¢n th6ng, khoa cua c~c lioh ki¢n di¢n tfr tfeh Cl,re?
7. Neu rtng dl,lng eua cae linh ki¢n di~n tfr tfeh cl!c?
8. Di6t Zener kMe di6uhUOng the ntto? Nell lffig dl,lng eua diat Zener?
9. JFET vi\ MOSFET khae nhau th€ ntto? D~c diem eua tranzito tfUemg la gl? PhAn bi~t s\! kh!'ic nhau giua tranzito tIuang va v6i tranuto thuemg? Nell ung d1}.ng eua chung?
10. PhAn bi¢t s\! kbac ohall giua diae va di6t? So scinh diae va triac?
11. UJT 13. gi? Neu ung dl,!ngcua UJT?
Chlldng3
KHAI QUAT VE cAc LlNH KleN £lIeN Til 56
3.1. KffAI QuAT vt Ki THU~T s6