NEXPERIA 74HC123D,653

74HC123D,653 is a dual retriggerable monostable multivibrator with reset. and output pulse width control. The basic output pulse width is programmed by selection of external components (REXT and CEXT). Once triggered this basic pulse width may be extended by retriggering either of the edge triggered inputs (n (active low)A or nB). By repeating this process, the output pulse period (nQ = HIGH, n(active low)Q = LOW) can be made as long as desired. Alternatively, an output delay can be terminated at any time by a LOW-going edge on input nRD. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC. Schmitt-trigger action in the nA and nB inputs, makes the circuit highly tolerant to slower input rise and fall times.