文档介绍：A、选择题 (3) (2) (2) (1) (1) (1) (2) (3) (2) (1) (3) (2) B、基本题当 Ui≥5 时, D 导通,则 Uo = Ui; 当 Ui<5 时, D 截止,则 Uo =5 v. (a )图:当 Ui≥E 时, D 导通,则 Uo =E=5v。当Ui<E 时, D 截止,则 Uo = Ui。(b )图:当 Ui≤E 时, D 导通,则 Uo = Ui; 当 Ui>E 时, D 截止,则 Uo =E=5v。(c )图:当 Ui≤E 时, D 导通,则 Uo =5v; 当 Ui>E 时, D 截止,则 Uo = Ui。(d )图:当 Ui<E 时, D 截止,则 Uo =E=5v; 当 Ui>E 时, D 导通,则 Uo = Ui。 (a )图:当 Ui≥0 时, D 导通,则 Uo = Ui; 当 Ui<0 时, D 截止,则 Uo =0。(b )图:当 Ui≥0 时, D 导通,则 Uo =o; 当 Ui<0 时, D 截止,则 Uo = Ui。 (1)U A=U B=0时,D A、D B 导通,则V y=0,I Db=I Db= (1/2) I R = mA ,I R =12/R=3mA 。(2)U A =3v ,U B =0 时, D A 截止, D B 导通,则 V y =0,I DB =I R =12/R= 3mA ,I DA=0。(3)U A =U B =3v 时,D A、D B 同时导通,则U Y =3v ,I R=( 12-3 ) /R= ,I DB =I DA=( 1/2 ) I R = 。 (1) Ua=6v , Ub=0 时, DA 导通, DB 截止,则 Vy= ( 10v*9k )/( 1k+9k ) =9v ,I Db =0, I DA =10v/ ( 1k+9k ) =1mA 。(2) Ua=6v , Ub= 时, D A、D B 导通,则 Vy= ( )/( 1k+9k ) *9k= , I R == ,I DB = ,I DA=( 6- ) /1k= 。(3)U a =U b =5v 时,D A、D B 都导通,则V y=( 5*9k )/( 9k+1k ) = ,I R == , I DA =I DB = 。 1 2 3 4 5 6 A B C D 6 5 4 3 2 1 D C B A Title Number Revision SizeB Date: 23-Dec-2010 Sheet of File: C:\Documents and Settings\Administrator\桌面\zhangshengqun\ Drawn By: R1 Dz R2 E 由于 Va=R2/(R1+R2)*E=20*1100/(900+1100)=11v>V Z, 则稳压管 D Z 稳