数字时钟电路.pdf

摘 要 数字钟是一种用数字电路技术实现日、时、分、秒计时的装置，与传统的机 械式时钟相比，具有更高的准确性和直观性，且无机械传动装置，具有更更长的 使用寿命，因此得到了广泛的使用。小到人们日常生活中的电子手表，大到车站、 码头、机场等公共场所的大型数显电子钟。 本课程设计要用通过简单的逻辑芯片实现数字时钟。要点在于用555 芯片连 接成输出1000 秒的多谐振荡器，然后经过74LS90 构成的分频器输出1HZ 的秒脉 冲,用74LS160(10进制计数器)连接成60 和24进制的计数器,再通过七段数码管 显示，外加上校时电路，整点报时电路即构成了简单数字钟。扩展电路可实现定 点报时功能。 关键字：多谐振荡器；分频器；计时电路；闹钟电路；校时电路；整点报时电路 1 目 录 1 设计内容及要求·······················································1 1.1 设计目的·························································1 1.2 设计内容和要求················································1 1.3 创新部分·························································1 2 系统总体设计方案····················································1 2.1 数字时钟的组成 ···············································1 2.2 原理分析·························································1 2.3 基本逻辑功能框图·············································2 3 器件选择································································2 3.1 555 集成定时器················································2 3.2 74LS160 ························································3 3.3 LED 显示屏·····················································5 3.4 4 位十进制同步可逆计数器74LS90 ······················5 3.5 4 位数值比较器74LS85 ······································7 2 4 数字时钟的电路设计·················································9 4.1 时钟振荡电路··················································9 4.1.1 555 多谐振荡器产生1KHz ··························9 4.1.2 时钟信号发生电路 ···································9 4.1.3 时钟振荡电路的Multisim 仿真·················10 4.2 分频器电路 ····················································11 4.3 秒脉冲发生器电路···········································12 4.4 分脉冲发生器电路 ··········································13