1/12

July 2001

s

HIGH SPEED :

s

LOW POWER DISSIPATION:

STAND BY STATE :

ACTIVE STATE :

s

HIGH NOISE IMMUNITY:

s

SYMMETRICAL OUTPUT IMPEDANCE:

s

BALANCED PROPAGATION DELAYS:

s

WIDE OPERATING VOLTAGE RANGE:

s

WIDE OUTPUT PULSE WIDTH RANGE :

s

PIN AND FUNCTION COMPATIBLE WITH

74 SERIES 123

DESCRIPTION

The

M74HC123

is

an

high

speed

CMOS

MONOSTABLE MULTIVIBRATOR fabricated with

There are two trigger inputs, A INPUT (negative

edge) and B INPUT (positive edge). These inputs

are valid for slow rising/falling signals, (tr=tf=l sec).

The device may also be triggered by using the

CLR

input

(positive-edge)

because

of

the

Schmitt-trigger input; after triggering the output

maintains the MONOSTABLE state for the time

period determined by the external resistor Rx and

capacitor Cx. When Cx > 10nF and Rx > 10K

Ω,

the output pulse width value is approsimatively

given by the formula : tW(OUT) = K · Cx · Rx.

(K

Taking CLR low breaks this MONOSTABLE

STATE. If the next trigger pulse occurs during the

MONOSTABLE

period

it

makes

the

MONOSTABLE period longer. Limit for values of

Cx and Rx : Cx : NO LIMIT

All inputs are equipped with protection circuits

against static discharge and transient excess

voltage.

M74HC123

DUAL RETRIGGERABLE MONOSTABLE MULTIVIBRATOR

PIN CONNECTION AND IEC LOGIC SYMBOLS

ORDER CODES

PACKAGE

TUBE

T & R

DIP

M74HC123B1R

SOP

M74HC123M1R

M74HC123RM13TR

TSSOP

M74HC123TTR

TSSOP

DIP

SOP