74HC595D单片机介绍

　　74HC595D，是一款单片机，属于微机的一种。

　　The 74HC/HCT595 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL （LSTTL）。 They are specified in compliance with JEDEC standard no. 7A. The 74HC/HCT595 is an 8-stage serial shift register with a storage register and 3-state outputs. The shift register and storage register have separate clocks. Data is shifted on the positive-going transitions of the SH_CP input. The data in each register is transferred to the storage register on a positive-going transition of the ST_CP input. If both clocks are connected together， the shift register will always be one clock pulse ahead of the storage register. The shift register has a serial input （DS） and a serial standard output （Q7’） for cascading. It is also provided with asynchronous reset （active LOW） for all 8 shift register stages. The storage register has 8 parallel 3-state bus driver outputs. Data in the storage register appears at the output whenever the output enable input （OE） is LOW.