DM74LS221 Datasheet | National Semiconductor

Description The DM74LS221 is a dual monostable multivibrator with Schmitt-trigger input Each device has three inputs permitting the choice of either leading-edge or trailing-edge triggering Pin (A) is an active-low trigger transition input and pin (B) is an active-high transition Schmitt-trigger input that allows jitter free triggering for inputs with transition rates as slow as 1 volt second This provides the input with excellent noise immunity Additionally an internal latching circuit at the input stage also provides a high immunity to VCC noise The clear (CLR) input can terminate the output pulse at a predetermined time independent of the timing ponents This (CLR) input also serves as a trigger input when it is pulsed with a low level pulse transition ( ) To obtain the best and trouble free operation from this device please read operating rules as well as the NSC one-shot application notes carefully and observe remendations Features Y A dual highly stable one-shot Y pensated for VCC and temperature variations Y Pin-out identical to ’LS123 (Note 1) Y Output pulse width range from 30 ns to 70 seconds Y Hysteresis provided at (B) input for added noise immunity Y Direct reset terminates output pulse Y Triggerable from CLEAR input Y DTL TTL patible Y Input clamp diodes Note 1 The pin-out is identical to ’LS123 but functionally it is not refer to Operating Rules 10 in this datasheet Functional Description The basic output pulse width is determined by selection of an external resistor (RX) and capacitor (CX) Once triggered the basic pulse width is independent of further input transitions and is a function of the timing ponents or it may be reduced or terminated by use of the active low CLEAR input Stable output pulse width ranging from 30 ns to 70 seconds is readily obtainable Connection Diagram Dual-In-Line Package TL F 6409 - 1 Order Number DM74LS221M or DM74LS221N See NS Package Number M16A or N16A Function Table Inputs Outputs CLEAR...