Chng 1. Linh kin bn dn

Chng 1. Linh kin bn dnNi dungLinh kin th ngCht bn dn DiodeTransistor lng cc BJTTransistor hiu ng trng FET

1.1. Linh kin th ng

3Khi nim v phn loi Linh kin th ng l linh kin ch tiu th nng lng ch khng c kh nng sinh ra nng lng. Quan h gia dng v p trn linh kin th ng l quan h tuyn tnh Cc linh kin th ng in hnh bao gm:in tr (Resistor)T in (Capacitor)Cun dy (Coil)Bin p (Transformer)

4in tr (Resistor)

in tr l linh kin in t c bn, n cn tr s lu thng ca dng in. Tc dng ca in tr trong mch in l xc nh mc dng v p.n v ca in tr l Ohm k hiu l . Bi s ca thng l Kilo, Mega v Giga1K = 103 1M = 106 1G = 109 in tr quang

Hnh dng thc t ca in tr

Nhit tr

in tr quang

Cc nh sn xut khng sn xut in tr vi mi gi tr m theo cc gi tr chun c EIA khuyn ngh, gi l tiu chun E vi cc h chnh l:E6 sai s 20%100, 150, 220, 330, 470, 680E12 sai s 10%100, 120, 150, 180, 220, 270, 330, 390, 470, 560, 680, 820E24 sai s 5%100, 110, 120, 130, 150, 160, 180, 200, 220, 240, 270, 300, 330, 360, 390, 430, 470, 510, 560, 620, 680, 750, 820, 910E48 sai s 2%E96 sai s 1%E128 sai s 0,25%; 0,5%; 0,1% v nh hn na c gi tr mong mun ngi ta mc in tr theo kiu ni tip, song song hoc kt hp5in tr (Resistor)

6in tr (Resistor)

in tr c gi tr khng i hoc c th thay i (bin tr)

in tr c gi tr khng i

Bin tr

Bin tr vi chnh (trimer): l loi c lm ch yu t carbon, kch thc nh v phi s dng tuoclovit xoay. T l iu chnh ca loi bin tr ny thng l logarit

7Cch c thng s in tr

c trc tip khi thn in tr ln (in tr dy qun) ghi gi tr in tr, cng sut v dung sai.v d: 22 , 25W, sai s 1% c gin tip theo quy c ch s v ch ci (in tr dn b mt) v m mu (in tr carbon hoc in tr film) tiu chun BS 1852 ca Anh Quy c 1: ch s cui cng (3 hoc 4) ch h s nhn ch ci ch n v R (hoc E hoc khng ghi) = K= 103 M = 106 v tr ch ci ch v tr du thp phn

8,2

0,003 0,75 M15 K

8Cch c thng s in tr

c gin tip theo quy c ch s v ch ci (in tr dn b mt) v m mu (in tr carbon hoc in tr film) tiu chun BS 1852 ca AnhQuy c 2: ch s cui cng ch h s nhn ch ci ch dung sai :F = 1%; G = 2%; J = 5%; K = 10%V d:K hiuThng s220F22 1%682J6,8 K 5%1K51,5 K153K15 K 10%

9Quy c m mu

MuVng 1,2S thcVng 3H s nhnVng 4Dung saiVng 5H s nhiten0100-Nu11011%100ppm21022%50ppmCam3103 1K3%15ppmVng41044%25ppmLc5105-Lam6106 - 1M-Tm 7107-Xm8--Trng9--Vng kim-10-15%Bch kim-10-210%

Vch mu ca in tr thuc E12 + Nu ch c 3 vng mu th sai s mc nh l 20%

+ Nu 6 vng mu th 3 vng u ch s thc

ng vai tr l phn t hn dng, trnh cho cc linh kin b ph hng do cng dng qu ln c s dng ch to cc dng c sinh hot (bn l, bp in hay bng n,) hoc cc thit b cng nghip (thit b sy, si,) Xc nh hng s thi gian: Trong mt s mch to xungPhi hp tr khng c s dng trong cc mch phn p phn cc cho cc linh kin in tng dng ca in tr

11T in

T in l linh kin th ng dng np v phng in tch (c kh nng tch v phng nng lng). N chn dng mt chiu nhng li cho dng xoay chiu i qua. K hiu v hnh dng thc t

K hiu v hnh dng thc t ca mt s loi t in

12T in

Bn ccCht in miin tch trong : l hng s in mi S l tit din hiu dng ca bn cc t d l khong cch gia hai bn cc t

n v tnh ln ca in dung l Fara nhng trn thc t y l gi tr rt ln nn ngi ta thng dng c s ca Fara l:MicroFara: 1F = 10-6 F NanoFara: 1nF = 10-9 FPicoFara: 1pF = 10-12 F

13

c trc tip: p dng cho t ha. Kch thc ln ghi y cc thng s: in dung, in p lm vic, di nhit .

c theo quy c v ch s v ch ci: p dng cho t a gm hoc mican v tnh bng pF

V d: 150000pF = 150 nF

Cch c thng s trn thn t

14Cch c thng s trn thn t

Cch c thng s trn thn t (gn ging in tr) M mu: p dng cho t film gm

MuSASBH s nhnDDung sai khi >10pFDung sai khi 0): diode dn in, trong mch c dng in chy qua. Khi ny c th coi diode nh mt kha in t ng (ngn mch) nu UAK > UD

39

UAK < UDUAK > UD

Nguyn tc lm vic ca diode (2)Diode lm vic da trn tnh cht dn in mt chiu ca chuyn tip P-N.Khi phn cc ngc (UAK < 0): diode khng dn in, trong mch ch c dng in ngc rt nh chy qua. Khi ny c th coi diode nh mt kha in t m (h mch).

40

c tuyn Vn-Ampe ca diodePhn thun ca c tuyn (UAK > 0)UD : in p ngng ca diode. UD 0,3V (Ge) UD 0,7V (Si)Ithmax l dng in thun cc i cho php ca diode in p ng vi gi tr Ithmax c gi l Ubh, c gi tr 0,8V ( Ge), 1,2V (Si).Vng phn cc thun c c trng l dng ln (mA), in p nh v in tr nhPhn ngc ca c tuyn (UAK < 0)Dng ngc bo ha c gi tr rt nh IS c nA Khi UAK = Udt (in p nh thng) th dng in ngc tng vt, gi l hin tng nh thng chuyn tip P - N Udt 12V i vi diode tch sng v khong vi chc V ti 1kV vi diode nn in.

41

Phn loi v ng dngDiode chnh luDiode n p (Zener)Diode bin dung (Varicap)Diode pht quang (LED), thu quang (Photo diode)Diode xuyn hm (tunnel), cao tn, xung42

Diode chnh lu (nn in)K hiu v hnh dng thc t

Cch xc nh cc ca diode: theo k hiu hoc dng Vn k.ng dngMch chnh luMch hn binMch dch mc

43

Mch chnh luMch chnh lu na chu k

Mch chnh lu c chu k

44

Mch hn binMch hn bin trn

Mch hn bin di

45

Mch dch mcLm thay i mc dc (mt chiu) ca tn hiu46

Diode n p (Zener)Diode Zene c cu to tng i c bit ch n c nng pha tp cht rt cao, c v bng thy tinh trong sut v kch thc kh nh.

47

Diode Zene lm vic trn on c tuyn ngc, li dng ch nh thng v in ca chuyn tip P-N n nh in p. Ngha l khi b phn cc ngc v lm vic trong vng nh thng th n khng b hng nh cc diode khc.in p nh thng ca diode Zene thng kh nh (vi chc Vn tr xung) .

0246

20406080100120140on c tuyn ngc ca diode ZeneDng in ngc(mA)

I

V

V

in p st trn diode gn nh khng i

Cc tham s quan trng ca diode n pin p n nh UZin tr trong RiCng sut nh mc PZ, n l cng sut tiu tn trn diode khi c dng IZ chy quaPZ = UZ . IZImin l tr s dng in nh nh ti im m hin tng nh thng n nhImax l tr s dng in cc i qua diode c xc nh bi cng sut tiu tn cc i diode (nu I > Imax diode s b chy)49

Mch n p dng diode ZenerMch n p c ti

50

Diode bin dung (Varicap)

51Gi tr in dung ca diode c tnh bng cng thc:Trong :: hng s in mi ca cht bn dnS: din tch mt ct ngang ca chuyn tip P Ndtx: b dy ca chuyn tip P-N

Gi tr ca Cv thng rt nh, khong t 2pF n 100pF. iu chnh gi tr ny ngi ta thay i gi tr ca dtx bng cch iu khin in p ngc t vo diode

LEDKhi c phn cc thun s pht ra nh sng Diode pht quang (LED)

52

Powersupply

VSRS

Photodiode c phn cc ngc v dn in khi c nh sng chiu voPhotodiodeDiode thu quang (photodiode)53

Transistor lng cc (BJT) Cu to, k hiu Kh nng khuch i Nguyn tc hot ng Cc s phn cc v nh im lm vic Cc s mc c bn

54

Cu to Transistor NPN

Min Colect pha tp thpC

NPN

Min Baz mng v pha tp thpB

Min Emit pha tp nhiuE

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Cu to Transistor PNP

NMin Baz mng v pha tp thpB

Min Emit pha tp nhiuE

56P

Min Colect pha tp thpC

P

EmitterK hiu Transistor NPN

Base

CollectorChiu mi tn ch chiu dng in qua chuyn tip Emit

EBC57

Collector

Base

Emitter

EBCK hiu Transistor PNP58

Tm tt v cu to ca TransistorTransistor c to thnh bi 2 chuyn tip P - N ghp lin tipTransistor c 3 cc: cc Colect (gp), cc Baz (gc) v cc Emit (pht).Chuyn tip gia Colect v Baz gi l chuyn tip Colect, k hiu l JCChuyn tip gia Emi v Baz gi l chuyn tip Emit, k hiu l JEHu ht cc ht dn pht x t min Emit, qua min gc Baz v b thu gp ti min ColectDng IB c gi tr nh nhng gi vai tr iu khin59

Nguyn tc lm vic ca TransistorTransistor c 2 ch lm vic ty vo trng thi phn cc ca cc chuyn tip.Transistor lm vic ch khuch i (cn gi l ch tch cc, iu khin c)- JE phn cc thun- JC phn cc ngc2. Transistor lm vic ch kha in t (khng iu khin c)JE v JC phn cc thun (dn bo ha)JE v JC phn cc ngc (ngt)60

Khuch i

RaVoK=

VoRaKh nng khuch i ca Transistor61

Tip gip JE phn cc thunV JC phn cc ngcNPN

Phn cc Transistor NPN

C

B

E

Dng in trn 3 cc

Hu ht cc ht dn pht x t Emit vt qua c min Baz do min Colecto htCh : IB nh hn nhiu IE v IC.ICIBIE

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Cc thnh phn dng in ch tch cc

JE c phn cc thun nn cc ht a s trong Emito tng cng khuch tn sang BazCc ht a s ca Emit phun vo Baz v tr thnh cc ht thiu s tri. Do chnh lch nng m chng s khuch tn ti b min in tch khng gian ca chuyn tip JC.Chuyn tip JC phn cc ngc nn s cun tri cc ht thiu s sang min Colect.

)63

IE = IC + IB (thng thng IB UB >UCKhi tnh ton ch mt chiu trong vng tch cc ta dng cc cng thc sau:UBE = 0.7VIC = IBIE= IB + IC = ( +1)IB74

ng ti tnh v im cng tc tnhng ti tnh c v trn c tuyn ra tnh ca transitor nghin cu dng in v in p mt chiu khi mc trong mt mch c th no .

im cng tc tnh (hay im tnh, im phn cc) l im nm trn ng ti tnh xc nh dng in v in p trn transitor khi khng c tn hiu t vo, ngha l xc nh iu kin phn cc cho transitor.

ng ti tnh v im cng tc tnh75

ng ti tnh

im cng tc tnh Q

Vcc

Vcc/Rt

iC(mA)

UCE(V)

Chn im cng tc tnhGiao im ca ng ti tnh v ng c tuyn ra gi l im cng tc tnh Q. Vic chn v tr cho Q c ngha rt ln i vi ch lm vic ca transistor.

Khi transistor lm vic ch khuch i, thng thng ngi ta chn Q nm gia ng ti tnh (gia vng tch cc) tn hiu u ra c th c bin ln nht m khng b mo. 76

n nh im cng tc tnhV tr ca im lm vic tnh rt quan trng trong hot ng ca BJT Nguyn nhn dn n s thay i v tr ca im Q:Nhit thay is ho gi ca linh kin theo thi gian hot ngs khng n nh ca ngun cung cp ...Trong yu t v nhit l yu t thng xuyn tc ng v c th hn ch c. Do tnh cht chung ca bn dn l c tnh in ph thuc vo nhit nn dng in v in p trn transistor ph thuc rt nhiu vo nhit . Ngha l im lm vic tnh s b di chuyn khi nhit thay i. nh hng ca nhit chnh l nh hng ti hai tham s l dng ngc ICB0 v in p UBE.UBE bin i khong 2,2mV/0C i vi transistor loi Si v -1,8mV/0C i vi transistor Ge.ICB0 tng gp 2 ln khi nhit tng 100C77

S phn cc c nh (1) Mch phn cc c nh

VCC l ngun cung cp mt chiuRB u t dng ngun Vcc v cc gc dn in p dng v cc gc.RC dn in p t dng ngun Vcc v cc gp.C1, C2: t ni tngDng in IB chy t dng ngun Vcc qua RB , qua BJT v m ngun.Dng in IC chy t dng ngun Vcc qua RC , qua BJT v m ngun.

78

S phn cc c nh (2) (xc nh im cng tc tnh Q)PT Kirchhoff cho vng in p pha u vo ta c phng trnh:VCC = UBE + RB .IB IB= (VCC UBE)/RB Khi lm vic ch khuch i UBE c gi tr rt nh do chuyn tip Emitter phn cc thun. Nn ta c:

Ta thy dng IB c gi tr khng i nn phng php ny c gi l phng php phn cc bng dng IB c nh. Vit phng trnh Kirchhoff cho vng in p pha u ra:VCC = UCE + RC .IC phng trnh ng ti tnhGi tr dng IC chy qua in tr RC (dng ICQ) c tnh theo cng thc:

tm gi tr in p UCEQ ta thay gi tr ICQ vo phng trnh ng ti tnh. Vy ta c:

Khi ny im cng tc tnh Q xc nh bng 3 gi tr (IBQ, ICQ, UCEQ)

79

S phn cc c nh (3)ng ti tnh v im cng tc tnh Minh ho trn c tuyn ra tnh v ng ti tnh ta cn xc nh hai im:Mt im trn trc tung tng ng vi in UCE =0 v IC = VCC/RCMt im trn trc honh tng ng vi IC = 0 v UCE = VCCim cng tc tnh ca mch l giao ca ng ti tnh v c tuyn ra IB = VCC/ RB

80

Khi nhit thay i, h s thay i lm cho IC thay i (v IC= IB). Do im lm vic tnh Q (ICQ, UCEQ)s thay i nhiu theo khi nhit thay i.H s n nh nhit

V IB khng i nn c IB = 0. Thay vo cng thc trn c:S= + 1Nhn xtH s n nh nhit S ln do lnMun thay i S phi thay i thay i BJT Mch b nh hng ln bi nhit . Trong thc t ch dng cch phn cc ny khi khng yu cu n nh nhit cao.

S phn cc c nh (4) n nh nhit

81

Bi tpCho s mch sau v h c tuyn ra nh hnh di yXc nh im cng tc tnh QMinh ho trn th c tuyn raNhn xt v hot ng ca mch

82

p n

82

S hi tip m in p (1)S mch

Hi tip m in p l mt phn in p ra c a ngc tr li u vo sao cho tc dng cu n ngc pha vi in p vo.VCC l ngun cung cp mt chiuRC dn in p t dng ngun VCC v cc gp.in tr RB khng ni trc tip vi ngun VCC m ni gia cc C v cc B. Ngha l cc B c cp ngun t VC, qua RB. Cch xc nh im cng tc tnh Q cng tng t nh phn trn

83

S hi tip m in p (2)S ny c n nh nhit tt hn s phn dng c nh Khi nhit tng dng IC tng ln st p trn RC tng in p ti cc C l VC gim xung m VB = VC IB.RB do VB cng gim xung, lm cho gc m UBE nh li, BJT dn yu i, tc l cc dng qua BJT gim (IC gim chng li s thay i ban u). Qu trnh hon ton ngc li khi nhit gim im cng tc tnh s n nh khi nhit thay iNh vy, nh in tr hi tip m RB m im lm vic tnh ca mch s n nh hn.84

Phn cc bng phn p (1) S phn cc bng phn pS tng ng Thevenin

R1, R2 to thnh mch phn p cp in p cho cc BRC dn in p dng ngun v cc C.RE l in tr hi tip m dng in, to in p trn cc E tu vo gi tr dng IE i qua BJT (do vy gi l t phn cc).Dng in trn RE s to mt st p trn n c xu hng chng li s phn cc thun ca lp tip xc pht n nh nhit cho mch85

Phn cc bng phn p (2)(xc nh im cng tc tnh)Thay s mch trn bng s tng ng Thevenin vi cc gi tr tng ng nh sau:

phng trnh Kirchhoff in p vo nh sau:

Phng trnh ng ti tnh nh sau:

T 2 phng trnh ny xc nh c Q tng t nh 2 s trn

86

86

Bi tpCho s mch sau v h c tuyn ra nh hnh di yXc nh cc thnh phn dng v p trn cc cc ca transistorXc nh im cng tc tnh QNhn xt v hot ng ca mch

87

88Ht phn:

Chuyn tip P-N (P-N junction)Diode Transistor lng cc (BJT)Transistor trng (FET)Mt s linh kin khc (UJT, SCR, Diac, Triac ...)Xem tip cc phn sau trong slide tip theo

1.4. Linh kin tch cc

Vng phn cc ngc

Vng phn cc thun

UBR

UD

1V

UAK(V)

ID(mA)

Phn t khuch i(Transistor)

Ngun cp 1 chiu

Ngun tn hiu vo (AC)

Tn hiu ra trn ti (AC)

Vng bo ho

Vng tch cc

Vng ngt

(mA)

iB= 50(mA)

iB= 40(mA)

iB= 30(mA)

iB= 20(mA)

iB= 10(mA)

iB= 0(mA)

Vcc

Vcc/RC

UCE(V)

IB=Vcc/RB

iC(mA)

Q

ng ti tnh

UCEQ

ICQ

b=100

12V

4mA

UCE(V)

IBQ= 24.04mA

iC(mA)

Q

ng ti tnh

5.1V

2.4mA

12V

9,9mA

UCE(V)

IBQ= 51,9mA

iC(mA)

Q

ng ti tnh

5.77V

5.19mA