时序逻辑电路(290)教学提纲.ppt

《时序逻辑电路(290)教学提纲.ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、时序逻辑电路(290)功能表R0(1)、R0(2)——置“0”端S9(1)、S9(2)——置“9”端，CPA单独接入脉冲，FA构成二进制计数器。CPB单独接入脉冲，FBFCFD构成五进制计数器。外部时钟CP是先送到CPA还是先送到CPB，在QDQCQBQA这四个输出端会形成不同的码制。2CPACPBR0(1)R0(2)S9(2)S9(1)NCNCVCCQAQDQBQCGND1234567141312111098QAQDQBQCS9(2)S9(1)R0(2)R0(1)CP1CPA74LS9074LS90管脚分布图3常用符号QAQBQCQDCPA74LS90CPB

2、S9(1)S9(0)R0(1)R0(1)4(1)CPA单独接入脉冲，FA构成二进制计数器。二进制计数器SdC1Rd&&CPAQAS9(1)S0(2)R0(2)R0(1)1J1KF0SdC1Rd1JC1RdRdSdC1Rd1J&&CP0CPBQ0QBQCQDS9(1)S9(2)R0(2)R0(1)C11K1J1K1J1K1KFAFBFCFD5(2)CP1单独接入脉冲，FBFCFD构成五进制计数器。1JC1RdRdSdC1Rd1J&CPBQBQCQDR0(2)R0(1)C11K1J1K1KFBFCFD&S9(1)S0(2)SdC1Rd&CP0Q0S0(1)S9(2

3、)1J1KFA五进制计数器6分析1JC1RdRdSdC1Rd1J&CPBQBQCQDR0(2)R0(1)C11K1J1K1KFBFCFD&S9(1)S9(2)7功能表0001111011001111010101111011101111110010111010008(3)CPA接入脉冲，QA接CPB脉冲，FAFBFCFD构成8421码计数器。SdC1Rd1JC1RdRdSdC1Rd1J&&CPACPBQAQBQCQDS9(1)S9(2)R0(2)R0(1)C11K1J1K1J1K1KFAFBFCFDCPB=QAQA变化，提供CPB脉冲。9(4)CPB接入脉冲，Q

4、D接CPA脉冲，FAFBFCFD构成5421码计数器。SdC1Rd1JC1RdRdSdC1Rd1J&&CPACPBQAQBQCQDS9(1)S9(2)R0(2)R0(1)C11K1J1K1J1K1KFAFBFCFDCPA=QDQD变化，提供CPA脉冲。10用7490构成任意进制计数器例1：用7490构成七进制计数器QDQCQBQA000000010010001101000101011001111000100111QAQBQCQDCPA74LS90CPBS9(1)S9(0)R0(1)R0(1)&实现电路QDQCQBQA0000000100100011010001

5、010110011110001001请看EDA：90计数器(七进制）.ca412例2：用7490构成八进制计数器QDQCQBQA000000010010001101000101011001111000100113QAQBQCQDCPA74LS90CPBS9(1)S9(0)R0(1)R0(1)实现电路QDQCQBQA0000000100100011010001010110011110001001请看EDA：90计数器(八进制）.ca414例2：用7490构成53进制计数器QDQCQBQA00000001001000110100010101100111100010

6、01QDQCQBQA0000000100100011010001010110011110001001高位低位15QAQBQCQDCPA74LS90CPBS9(1)S9(0)R0(1)R0(1)实现电路QAQBQCQDCPA74LS90CPBS9(1)S9(0)R0(1)R0(1)高位低位&16结束17此课件下载可自行编辑修改，仅供参考！感谢您的支持，我们努力做得更好！谢谢