DM74LS122 Datasheet, PDF (1/6 Pages) National Semiconductor (TI) – DM74LS122 Retriggerable One-Shot with Clear and Complementary Outputs

May 1989
DM74LS122 Retriggerable One-Shot with
Clear and Complementary Outputs
General Description
The DM74LS122 is a retriggerable monostable multivibrator
featuring both positive and negative edge triggering with
complementary outputs An internal 10 kX timing resistor is
provided for design convenience minimizing component
count and layout problems This device can be used with a
single external capacitor The ’LS122 has two active-low
transition triggering inputs (A) two active-high transition trig-
gering inputs (B) and a CLEAR input that terminates the
output pulse width at a predetermined time independent of
the timing components The clear (CLR) input also serves
as a trigger input when it is pulsed with a low level pulse
transition ( ) To obtain optimum and trouble free opera-
tion please read operating rules and NSC one-shot applica-
tion notes carefully and observe recommendations
Features
Y _{DC triggered from active-high transition or active-low}
transition inputs
Y _{Retriggerable to 100% duty cycle}
Y _{Over-riding clear terminates output pulse}
Y _{Internal 10 kX timing resistor}
Y _{TTL DTL compatible}
Y _{Compensated for VCC and temperature variations}
Y _{Input clamp diodes}
Functional Description
The basic output pulse width is determined by selection of
the internal resistor R_INT or an external resistor (R_X) and
capacitor (C_X) Once triggered the output pulse width may
be extended by retriggering the gated active-low (A) tran-
sition inputs or the active-high transition (B) inputs or the
CLEAR input The output pulse width can be reduced or
terminated by overriding it with the active-low CLEAR input
Connection Diagram
Function Table
Dual-In-Line Package
Inputs
CLEAR A1 A2 B1 B2
L
X
X
X
X
X
H
H
X
X
X
X
X
L
X
X
X
X
X
L
H
L XuH
H
L X Hu
H
X LuH
H
X L Hu
H
HvH H
H
vv H H
H
vH H H
u
L
X
H
H
TL F 6385 – 1
u
X
L
H
H
Order Number DM74LS122M or DM74LS122N
H e High Logic Level
See NS Package Number M14A or N14A
L e Low Logic Level
X e Can Be Either Low or High
u e Positive Going Transition
v e Negative Going Transition
e A Positive Pulse
e A Negative Pulse
Outputs
Q
Q
L
H
L
H
L
H
L
H
C1995 National Semiconductor Corporation TL F 6385
RRD-B30M105 Printed in U S A