数字电路与数字逻辑-第四章-2ppt课件

1、二、译码器 (2) 3 8 线译码器 (3) 使能端的作用 1.二进制译码器 (1) 2 4 线译码器 (4) 用译码器设计组合逻辑电路 2.二十进制译码器 (1) 七段数码管 (2) 数字显示译码器7448 3. 数字显示译码器 三、数据选择器 1. 四选一数据选择器 二、译码器 译码：将输入的每个代码的含义“翻译过来，给出相应的输出信号。 1.二进制译码器 2n个 n位二进制代码2n个互不一样的形状(1) 2 4 线译码器 123456ABCD654321DCBAT itleNum berR evisionSizeBDate:16-Feb-2002Sheet of File:C :Prog

2、ram FilesDesign E xplorer 99 SE L ibraryYangHengXinM yDesign.ddbDrawn B y:&11111&ENAAYYYY012301图 4.2.5 (a) 逻辑图123456ABCD654321DCBAT itleN um berR evisionSizeBD ate:16-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y:AAYYYYE N013012

3、2/4(b) 简化符号E：使能端，低电平有效； A1 、A0 地址输入端； Y3Y0 译码输出端； 表 4.2.4 24 线译码器的功能表 1 1 0 11 000001EN使能输入1 1 1 01 11 0 1 10 10 1 1 1 0 01 1 1 1 Y0 Y1 Y2 Y3A1 A0 输 出输 入E=0 时，器件任务，算出 输入的一组二进制代码对应的十进制数，以此数作为下标的输出端被选中(输出0)。24线译码器的逻辑表达式；器件不任务 ；器件任务EN=1，Yi =1 ( i = 0,1,2,3 )EN=0，Yi = mi ( i = 0,1,2,3 )图 4.2.6 双24线译码器74

4、的简化逻辑符号123456ABCD654321DCBATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:1Y1Y1Y1Y2Y2Y2Y2Y1A1A1EN2EN2A2A01010123012374139(2) 3 8 线译码器 123456ABCD654321DCBATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program

5、FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By: Y Y Y Y Y Y Y YAAAEEE0112A012345677413822B图 4.2.7 (a) 简化符号E1、E2A、E2B：使能端； A2、A1、A0 地址输入端； Y7Y0 译码输出端； 表 4.2.5 38 线译码器74的功能表 1 1 1 1 1 0 1 11 0 1 1 01 1 1 1 1 1 0 11 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0 1E1 E2A+E2B使能输入1 1 1 1 0 1 1 11 0 0

6、1 1 1 0 1 1 1 10 1 11 1 0 1 1 1 1 10 1 01 0 1 1 1 1 1 10 0 11 1 1 1 1 1 1 01 1 10 1 1 1 1 1 1 10 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 A2 A1 A0 输 出输 入38线译码器74的逻辑表达式；器件不任务 ；器件任务E1=1和E2A+E2B=0同时满足，Yi = mi ( i = 0,1,7 )E1=1和E2A+E2B=0不同时满足，Yi =1 ( i = 0,1,7 )(3) 使能端的作用 扩展地址输入端 1234

7、56ABCD654321DCBATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:1Y1Y1Y1Y2Y2Y2Y2Y1A1A1EN2EN2A2A010101230123741391AAAYYYYYYYY01234567012图 4.2.8 (a) 表 4.2.6 24 线译码器扩展为 38 线译码器的真值表 1 1 1 1 1 1 1 0 1 0 1 1 1 Y0 Y1 Y2 Y3 Y4 Y

8、5 Y6 Y7 A2 A1 A0 1 0 1 0 1 0 0 1 0 1 0 1 0 11EN 2EN 使能输入 1 1 1 1 1 0 1 1 1 0 1 1 1 1 1 0 1 1 1 1 0 0 1 1 1 0 1 1 1 1 0 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 0 1 0 1 0 1 1 1 1 1 1 0 0 1 0 1 1 1 1 1 1 1 0 0 0 1Y0 1Y1 1Y2 1Y3 2Y0 2Y1 2Y2 2Y3 A2 A1 A0 输 出 输 入 123456ABCD654321DCBAT itleN um berR evis

9、ionSizeBD ate:17-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y:(1)(2)100YYY Y Y Y YYY YYY Y Y Y YAAAA0123012345678910111213 14 15 Y Y Y Y Y Y Y YAAAEEE0112A012345677413822B Y Y Y Y Y Y Y YAAAEEE0112A012345677413822B图 4.2.8 (b) 构造数据分配器 1

10、23456ABCD654321DCBATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:AAYYYYEN0130122/4ABDYYYY0123123456ABCD654321DCBATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHen

11、gXinMyDesign.ddbDrawn By:DA BYYYY0123(b) 图 4.2.9 (a) 例如：AB = 00，那么输出选中Y0通道，Y0 = D。 由于 D = 0， Y0 = 0；D = 1，Y0 = 1 。所以，Y0 = D。(4) 用译码器设计组合逻辑电路 原理：译码器每个输出端分别与某一个最小项高电平译码或某一个最小项非低电平译码相对应。例1 用74实现函数 F = AB + AC 。解：F (A,B,C) = AB + AC = m4 + m6 + m7 = m4 + m6 + m7 = m4 m6 m7 = Y4 Y6 Y7 123456ABCD654321DCB

12、ATitleNumberRevisionSizeBDate:17-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:&ABCVCCF Y Y Y Y Y Y Y YAAAEEE0112A012345677413822B图 4.2.10 (a) 另，F (C,B,A) = AB + AC = m1 + m3 + m7 = m1 + m3 + m7 = Y1 Y3 Y7 123456ABCD654321DCBAT itleN um berR evi

13、sionSizeBD ate:17-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y:& Y Y Y Y Y Y Y YAAAEEE0112A012345677413822BCBAVC CF图 4.2.10 (b) 例2 用74设计一个多输出组合网络，它的输入为A、B、C三个变量，输出为下面三个函数。F3 = A + B + CF2 = A + CF1 = AC + BC 解：F1(A,B,C) = AC + BC =

14、 m1 + m5 + m7= m1 m5 m7 F2(A,B,C) = A + C = m0+m2+m4+m5+m6+m7= m0+m2+m4+m5+m6+m7= m1 + m3 = m1 m3 = Y1 Y3 F3(A,B,C) = A+B+C = A B C = m0 =Y0123456ABCD654321DCBAT itleN um berR evisionSizeBD ate:17-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw

15、 n B y:&ABCVFFF123C C Y Y Y Y Y Y Y YAAAEEE0112A012345677413822B图 4.2.11 2.二十进制译码器 123456ABCD654321DCBAT itleN um berR evisionSizeBD ate:17-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y: Y Y Y Y Y Y Y YAAAA0131234567874422YY90图 4.2.

16、12 (c) 8421BCD码译码器7442 余3BCD码译码器7443 余3格雷BCD码译码器7444 A3 A0：地址输入端； Y9 Y0 ：输出端。 表 4.2.7二十进制译码器 7442的功能表 1 1 1 1 1 1 1 0 1 1 0 1 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0 1 1 1 1 1 0 1 1 1 1 1 0 1 0 0 1 1 1 0 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 1 1 0 1 1 0 0 0 1 1 0 1 1 1 1 1 1 1 0 0 1 0 1

17、0 1 1 1 1 1 1 1 1 0 0 0 1 0 1 1 1 1 1 1 1 1 1 0 0 0 0 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 A3 A2 A1 A0 输 出 输 入续表 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1 1 1 1 1 1 1 1 0 1 0 0

18、1 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 Y8 Y9 A3 A2 A1 A0 输 出 输 入数字显示译 码 器BCD码3. 数字显示译码器 七 段数码管(1) 七段数码管 半导体数码管 液 晶数码管 共阳极 共阴极 123456ABCD654321DCBATitleNumberRevisionSizeBDate:18-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:abcdefgD.P12345678910(a) 外形图123456ABCD

19、654321DCBATitleNumberRevisionSizeBDate:18-Feb-2002Sheet of File:C:Program FilesDesign Explorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By:abcdefgD.P123,84567910公共阴极(b) 等效电路图 4.2.13 C391E(2) 数字显示译码器7448 123456ABCD654321DCBATitleNumberRevisionSizeBDate:18-Feb-2002Sheet of File:C:Program FilesDesign E

20、xplorer 99 SELibraryYangHengXinMyDesign.ddbDrawn By: Y Y Y Y Y Y YAAARBILTBI/RBO01abcdefg74482A3简化符号A3A0：8421BCD输入端YaYg：七段输出端LT：灯光测试输入端RBI：串行灭零输入端BI / RBO：熄灭输入/串行灭零输出端123456ABCD654321DCBAT itleN um berR evisionSizeBD ate:18-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH

21、 engX inM yD esign.ddbD raw n B y:abcdef0afggbcabdegabcdgbcfgacdfgcdefabc1234567abcdef8ggbcdegcdgbfgadfgdef9101112131415图 4.2.15 015十六个字符显示 表 4.2.8 7448功能表 1 1 1 0 0 0 0 1 0 1 1 1 1 7 1 1 1 1 1 1 1 1 1 0 0 0 1 8 1 1 1 0 0 1 1 0 0 1 1 1 1 1 1 0 1 1 0 1 1 0 1 1 0 0 1 1 1 1 1 1 0 0 1 1 1 0 1 1 0 1 0 1

22、1 0 0 0 0 1 1 1 1 1 1 0 Ya Yb Yc Yd Ye Yf Yg 输 出 1 1 1 1 1 1 1 1 LT 1 RBI 1 1 1 1 1 1 1 1 BI / RBO 1 0 0 1 0 1 1 0 0 1 0 1 0 1 0 0 0 0 1 1 0 0 1 0 0 0 0 1 0 0 0 0 A3 A2 A1 A0 输 入 译 码 显 示 阐明 5 4 3 6 9 2 1 0 十进制 数 或 功 能 续表 测试 1 1 1 1 1 1 1 1 0 LT=0 灭零 0 0 0 0 0 0 0 0 0 0 0 0 0 1 RBI=0 0 0 0 0 0 0 0 0

23、0 0 0 0 0 0 0 0 0 1 1 1 1 1 0 0 1 0 1 1 0 1 0 0 0 1 1 0 0 1 1 0 0 1 0 0 0 1 1 0 1 Ya Yb Yc Yd Ye Yf Yg 输 出 1 1 1 1 1 1 LT RBI 0 1 1 1 1 1 1 BI / RBO 1 1 1 1 1 1 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 0 A3 A2 A1 A0 输 入 熄灭 译 码 显 示 阐明 15 14 13 BI=0 12 11 10 十进制 数 或 功 能 图 4.2.17 用7448驱动BS201A的衔接方法123456ABCD6

24、54321DCBAT itleN um berR evisionSizeBD ate:18-Feb-2002Sheet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y: Y Y Y Y Y Y YAAAR B ILTB I/R B O01abcdefg74482A3abcdefgvccBS201AAAAA101231K7 123456ABCD654321DCBAT itleN um berR evisionSizeBD ate:18-Feb-2002S

25、heet of File:C :Program FilesD esign E xplorer 99 SE L ibraryY angH engX inM yD esign.ddbD raw n B y: Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag7448 Y YRBIBI / RBOag744811图 4.2.18 有灭零控制的8位数码显示系统三、数据选择器 123456ABCD654321DCBATitleNumberRevisionSizeBDate:18-Feb-2002Sh