555 is a very commonly used IC for generating accurate timing pulses. It is an 8pin timer IC and has mainly two modes of operation: monostable and astable. In monostable mode time delay of the pulses can be precisely controlled by an external resistor and a capacitor whereas in astable mode the frequency & duty cycle are controlled by two external resistors and a capacitor. 555 is very commonly used for generating time delays and pulses.
|2||Voltage below 1/3 Vcc to trigger the pulse||Trigger|
|4||Active low; interrupts the timing interval at Output||Reset|
|5||Provides access to the internal voltage divider; default 2/3 Vcc||Control Voltage|
|6||The pulse ends when the voltage is greater than Control||Threshold|
|7||Open collector output; to discharge the capacitor||Discharge|
|8||Supply voltage; 5V (4.5V – 16 V)||Vcc|