TLF5206

January 1988

MM54HC123AMM74HC123A

Dual Retriggerable Monostable Multivibrator

General Description

The MM5474HC123A high speed monostable multivibra-

tors (one shots) utilize advanced silicon-gate CMOS tech-

nology They feature speeds comparable to low power

Schottky TTL circuitry while retaining the low power and

high noise immunity characteristic of CMOS circuits

Each multivibrator features both a negative A and a posi-

tive B transition triggered input either of which can be

used as an inhibit input Also included is a clear input that

when taken low resets the one shot The ’HC123 can be

triggered on the positive transition of the clear while A is

held low and B is held high

The ’HC123A is retriggerable That is it may be triggered

repeatedly while their outputs are generating a pulse and

the pulse will be extended

Pulse width stability over a wide range of temperature and

supply is achieved using linear CMOS techniques The out-

is in seconds R is in ohms and C is in farads All inputs are

protected from damage due to static discharge by diodes to

Features

Y

Typical propagation delay 25 ns

Y

Wide power supply range 2V – 6V

Y

Low quiescent current 80 mA maximum (74HC Series)

Y

Low input current 1 mA maximum

Y

Fanout of 10 LS-TTL loads

Y

Y

Wide pulse range 400 ns to % (typ)

Y

Y

Schmitt TriggerAB inputs enable infinite signal input

rise and fall times

Connection Diagram

Dual-In-Line Package

TLF5206 – 1

Top View

Order Number MM54HC123A or MM74HC123A

Timing Component

TLF5206 – 2

Note

Pin 6 and Pin 14 must be

hard-wired to GND

Truth Table

Inputs

Outputs

Clear

AB

Q

Q

LX

X

L

H

XH

X

L

H

XX

L

L

H

HL

u

H

v

H

u

LH

e

One High Level Pulse

e

One Low Level Pulse

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A