NE555P.pdf

Texas Instruments NE555 Single-Precision Timer

Texas Instruments NE555 Single-Precision Timers are precision timing circuits capable of generating accurate time delays or oscillations. In time delay or monostable mode, the timing interval is controlled by a single external resistor and capacitor network; in astable mode, frequency and duty cycle are independently controlled by two external resistors and an external capacitor. Typically, the threshold and trigger levels of this timer are two-thirds and one-third VCC, respectively, and these levels can be changed using the control voltage terminals. When the trigger input is lower than the trigger level, the timer runs and generates a high output; if the trigger input is higher than the trigger level and the threshold input is higher than the threshold level, the timer runs and resets and generates a low output. The reset (RESET) input overrides all other inputs and can be used to start a new timing cycle.