The DM74LS123 is a dual retriggerable monostable multivibrator capable of generating output pulses from a few nano-seconds to extremely long duration up to 100% duty cycle. Each device has three inputs permitting the choice of either leading edge or trailing edge triggering. Pin (A) is an active-LOW transition trigger input and pin (B) is an active-HIGH transition trigger input. The clear (CLR) input terminates the output pulse at a predetermined time independent of the timing components. The clear input also serves as a trigger input when it is pulsed with a low level pulse transition. To obtain the best trouble free operation from this device please read the operating rules as well as the Fairchild Semiconductor one-shot application notes carefully and observe recommendations.
DC triggered from active-HIGH transition or active-LOWtransition inputs