NE555DR | Texas Instruments

Precision Timer, NE555DR, Texas Instruments

The NE555DR timer is a precision timing circuit capable of producing an accurate time delay or oscillation. In time-delay or monostable operating modes, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle are controlled independently with two external resistors and a single external capacitor. The timer has a trigger level equal to approximately one-third of the supply voltage and a threshold level equal to approximately two-thirds of the supply voltage. These levels can be altered by use of the control voltage pin (CONT). When the trigger input (TRIG) is less than the trigger level, the flip-flop is set and the output goes high. If TRIG is greater than the trigger level and the threshold input (THRES) is greater than the threshold level, the flip-flop is reset and the output is low. The reset input (RESET) overrides all other inputs and is used to initiate a new timing cycle. If RESET is low, the flip-flop is reset and the output is low.

Features

• Timing from microseconds to hours
• Adjustable duty cycle

Applications

• Pulse-shaping circuits
• Missing-pulse detectors
• Pulse-width modulators
• Pulse-position modulators
• Sequential timers
• Pulse generators
• Frequency dividers
• Industrial controls