NE555, NE555Y, SA555, SE555, SE555C PRECISION TIMERS

►Timing From Microseconds to Hours

►Astable or Monostable Operation

►Adjustable Duty Cycle

►TTL-Compatible Output Can Sink or Source up to 200 mA
►Functionally Interchangeable With the Signetics NE555, SA555, SE555, SE555C; Have Same Pinout

SE555C FROM TI IS NOT RECOMMENDED FOR NEW DESIGNS

description

These devices are precision monolithic timing circuits capable of producing accurate time delays or oscillation. In the time-delay 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 may be independently controlled with two external resistors and a single external capacitor.

The threshold and trigger levels are normally 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. RESET 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. Whenever the output is low, a low-impedance path is provided between DISCH and ground.

The output circuit is capable of sinking or sourcing current up to 200 mA. Operation is specified for supplies of 5 V to 15 V. With a 5-V supply, output levels are compatible with TTL inputs. The NE555 is characterized for operation from 0°C to 70°C. The SA555 is characterized for operation from –40°C to 85°C. The SE555 and SE555C are characterized for operation over the full military range of –55°C to 125°C.

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