Dual Non-Retriggerable One-Shot - Fairchild Semiconductor
Description
DM74LS221 Dual Non-Retriggerable One-Shot with Clear and Complementary Outputs
August 1986 Revised April 2000
DM74LS221 Dual Non-Retriggerable One-Shot with Clear and Complementary Outputs
General 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 components.
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 Fairchild Semiconductor one-shot application notes carefully and observe recommendations.
Features
s A dual, highly stable one-shot s Compensated for VCC and temperature variations s Pin-out identical to DM74LS123 (Note 1) s Output pulse width range from 30 ns to 70 seconds s Hysteresis provided at (B) input for added noise immunity s Direct reset terminates output pulse s Triggerable from CLEAR input s DTL, TTL compatible s Input clamp diodes
Note 1: The pin-out is identical to DM74LS123 but, functionally it is not; refer to Operating Rules #10 in this datasheet.
Ordering Code:
Order Number DM74LS221M DM74LS221SJ DM74LS221N Package Number M16A M16D N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.
150 Narrow 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.
3mm Wide 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.
300 Wide
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