NE555 timer

These devices are precision timing circuits capable of producing accurate time delays or oscillation. In the timedelay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor. The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. These levels can be altered by use of the control-voltage terminal. When the trigger input falls below the trigger level, the flip-flop is set, and the output goes high. If the trigger input is above the trigger level and the threshold input is above the threshold level, the flip-flop is reset and the output is low. The reset (RESET) input can override all other inputs and can be used to initiate a new timing cycle. When RESET goes low, the flip-flop is reset, and the output goes low. When the output is low, a lowimpedance path is provided between discharge (DISCH) and ground.

Technical Specification

• Timing from microseconds to hours
• Astable or monostable operation
• Adjustable duty cycle
• TTL compatible output can source or sink up to 200mA
• “Green” Molding Compound (No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 1)