LM555CN - Highly Stable 555 Timer

The LM555 is a highly stable device for generating accurate time delays or oscillations. Additional terminals are provided for triggering or resetting if desired.

It has two main operation modes:

  1. Time delay mode, or monostable operation - the delay is precisely set using one external resistor and capacitor.
  2. Oscillator mode, or astable operation - the free running frequency and duty cycle are accurately controlled by two external resistors and one capacitor.


Pin Functions

Pin I/O Description
No Name
5 Control Voltage I Controls the threshold and trigger levels, determines the pulse width of the output waveform
7 Discharge I Discharges a capacitor between intervals, toggles the output from high to low when voltages reaches 2/3 of the supply voltage
1 GND O Ground Voltage
3 Output O Output driven waveform
4 Reset I Negative pulse applied on the pin to disable or reset the timer
6 Threshold I Compares the voltage applied to the terminal to the 2/3 value of the supply voltage, and determines the set state of the internal flip-flop
2 Trigger I Triggers the internal flip-flop transition from set to reset
8 VCC I Supply voltage relative to ground