SLFS023B - APRIL 1978 - REVISED SEPTEMBER 1997
These devices provide two monolithic, independent timing circuits of the NE555, SA555, SE555, or SE555C type in each package. These circuits can be operated in the astable or the monostable mode with external resistor-capacitor timing control. The basic timing provided by the RC time constant may be actively controlled by modulating the bias of the control voltage input.
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 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 input can override all other inputs and can be used to initiate a new timing cycle. When the reset input goes low, the flip-flop is reset and the output goes low. Whenever the output is low, a low impedance path is provided between the discharge terminal and ground.
The NE556 is characterized for operation from 0°C to 70°C. The SA556 is characterized for operation from - 40°C to 85°C, and the SE556 and SE556C are characterized for operation over the full military range of - 55°C to 125°C.
View more information about generic part numbers:NE556, SA556, SE556
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