The LM555 is a highly stable device for generating accurate time delays or oscillation.
Additional terminals are provided for triggering or resetting if desired. In the time delay mode of
operation, the time is precisely controlled by one external resistor and capacitor. For a stable
operation as an oscillator, the free running frequency and duty cycle are accurately controlled
with two external resistors and one capacitor. The circuit may be triggered and reset on falling
waveforms, and the output circuit can source or sink up to 200 mA or drive TTL circuits.
