A low pulse on this pin (below 1/3 of VCC) sets the internal flip-flop and makes the output go HIGH. When the voltage on this pin reaches 2/3 of VCC, it resets the flip-flop, and the output goes LOW.

The 74HC595 is an 8-bit serial-in, parallel-out shift register IC that is commonly used to drive leds motor or any other electronic equipment. PIN(Q0 - Q7) Output pin of the IC, that can be controlled ...