The 74HC595 8 Bit Serial To Parallel Shift Register IC is high speed shift register utilizes advanced silicon-gate CMOS technology. 74HC595 device possesses the high noise immunity and low power consumption of standard CMOS integrated circuits, as well as the ability to drive 15 LS-TTL loads. This device contains an 8-bit serial-in, parallel-out shift register that feeds an 8-bit D-type storage register. The storage register has 8 3-STATE outputs. Separate clocks are provided for both the shift register and the storage register.
The shift register has a direct-overriding clear, serial input, and serial output (standard) pins for cascading. Both the shift register and storage register of 74HC595 use positive-edge triggered clocks. If both clocks are connected together, the shift register state will always be one clock pulse ahead of the storage register. See more information in datasheet of 74HC595.