© 2000 Fairchild Semiconductor Corporation

DS006386

www.fairchildsemi.com

August 1986

Revised April 2000

DM74LS123

Dual Retriggerable One-Shot

with Clear and Complementary Outputs

General Description

The DM74LS123 is a dual retriggerable monostable multi-

vibrator capable of generating output pulses from a few

nano-seconds to extremely long duration up to 100% duty

cycle. Each device has three inputs permitting the choice of

either leading edge or trailing edge triggering. Pin (A) is an

active-LOW transition trigger input and pin (B) is an active-

HIGH transition trigger input. The clear (CLR) input termi-

nates the output pulse at a predetermined time indepen-

dent of the timing components. The clear input also serves

as a trigger input when it is pulsed with a low level pulse

transition (

). To obtain the best trouble free operation

from this device please read the operating rules as well as

the Fairchild Semiconductor one-shot application notes

carefully and observe recommendations.

Features

s DC triggered from active-HIGH transition or active-LOW

transition inputs

s Retriggerable to 100% duty cycle

s Triggerable from CLEAR input

s DTL, TTL compatible

s Input clamp diodes

Ordering Code:

Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.

Connection Diagram

Function Table

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

Order Number

Package Number

Package Description

DM74LS123M

M16A

16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

DM74LS123SJ

M16D

16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide

DM74LS123N

N16E

16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

Inputs

Outputs

CLEAR

A

B

Q

Q

LX

X

L

H

XH

X

L

H

XX

L

L

H

HL

↑



H

↓

H



↑

LH