DM74LS221

· A dual, highly stable one-shot
· Compensated for VCC and temperature variations
· Pin-out identical to DM74LS123 (Note 1)
· Output pulse width range from 30 ns to 70 seconds
· Hysteresis provided at (B) input for added noise immunity
· Direct reset terminates output pulse
· Triggerable from CLEAR input
· DTL, TTL compatible
· 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.

Supply Voltage ..........................................................7V
Input Voltage ............................................................7V
Operating Free Air Temperature Range ...0°C to +70°C
Storage Temperature Range .............−65°C to +150°C

Note 3: The "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The "Recommended Operating Conditions" table will define the conditions for actual device operation.

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 V_CC 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 DM74LS221 device please read operating rules as well as the Fairchild Semiconductor one-shot application notes carefully and observe recommendations.