数字设计课件数字电路第六章.ppt

ABCG1G2AG2BY0Y1Y2Y3Y4Y5Y6Y774x138EN1EN2_LEN3_LSSRC0SSRC1SSRC2fighting（冲突）利用使能端进行时序控制三态器件允许信号共享单个“同线”（partyline）典型的三态器件，进入高阻态比离开高阻态快P0P1P7SDATAEN1EN2_L,EN3_Lmax(tpLZmax,tpHZmax)min(tpZLmin,tpZHmin)SSRC[2:0]01237SDATAP0P1P2P3P7DeadTime(截止时间)StandardSSIandMSIThree-StateBuffer

(标准SSI和MSI三态缓冲器)The74x541Octalthree-statebufferA1A2A3A4A5A6A7A8G1G2Y1Y2Y3Y4Y5Y6Y7Y874x541A1A8G1G2Y1Y874x541DB[0:7]A1A8G1G2Y1Y874x541NotationofDataBus（数据总线的表示法）A1B1DIRTransferDatainEitherDirectionsByUsingThree-StateTransceiver(利用三态缓冲器实现数据双向传送)BusTransceiver(总线收发)DIRG_L6.7Multiplexer（多路复用器）DigitalSwitch,Multi-Switch,DataSelector(又称数据开关、多路开关、数据选择器)（缩写：MUX）UnderSelectControllingSignals,SelectOneoftheMulti-InputstotheOutput(在选择控制信号的作用下，从多个输入数据中选择其中一个作为输出。)MultiplexerENSELD0Dn-1YEnable使能Select选择n个1位数据源数据输出（1位）ENSELD0Dn-1YEnable(使能)Select(选择)NDataSources(n个b位数据源)DataOutput(数据输出)（b位）EN_LCBAYY_L1XXX0000000100100011010001010110011101D0D0’D1D1’D2D2’D3D3’D4D4’D5D5’D6D6’D7D7’(8输入1位多路复用器)TruthTablefora74x1518-Input,1-bitMultiplexerENABCD0D1D2D3D4D5D6D7YY74x15143211514131211109756EN_LCBAYY_L1XXX0000000100100011010001010110011101D0D0’D1D1’D2D2’D3D3’D4D4’D5D5’D6D6’D7D7’(8输入1位多路复用器)TruthTablefora74x1518-Input,1-bitMultiplexerHowtogetalogicequationforaMUXoutput?输入G_LS1X000100001A2A3A4A1B2B3B4B(2输入4位多路复用器)TruthTablefora74x157输出1Y2Y3Y4Y