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DM74LS221SJ View Datasheet(PDF) - Fairchild Semiconductor

Part Name
Description
Manufacturer
DM74LS221SJ Datasheet PDF : 8 Pages
1 2 3 4 5 6 7 8
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 permit-
ting the choice of either leading-edge or trailing-edge trig-
gering. 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 Fair-
child 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 Package Number
Package Description
DM74LS221M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74LS221SJ
M16D
16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide
DM74LS221N
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram
Function Table
Inputs
Outputs
CLEAR
A
B
Q
Q
L
X
X
L
H
X
H
X
L
H
X
X
H
L
H
(Note 2)
L
L
H
H
L
H
H = HIGH Logic Level
L = LOW Logic Level
X = Can Be Either LOW or HIGH
↑ = Positive Going Transition
↓ = Negative Going Transition
= A Positive Pulse
= A Negative Pulse
Note 2: This mode of triggering requires first the B input be set from a
LOW-to-HIGH level while the CLEAR input is maintained at logic LOW
level. Then with the B input at logic HIGH level, the CLEAR input whose
positive transition from LOW-to-HIGH will trigger an output pulse.
© 2000 Fairchild Semiconductor Corporation DS006409
www.fairchildsemi.com
 

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