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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 221

DESCRIPTION

The

M74HC221

is

an

high

speed

CMOS

MONOSTABLE MULTIVIBRATOR fabricated with

There are two trigger inputs, A INPUT (negative

edge) and B INPUT (positive edge).

Triggering on the B input occurs at a particular

voltage threshold and is not related to rise and fall

time of the applied pulse. The device may also be

trigger by using the CLR input (positive edge)

because

of

the

Schimtt-trigger

input;

after

triggering

the

output

maintains

the

MONOSTABLE

STATE

for

the

time

period

determined by the external resistor Rx and

capacitor Cx. 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

K

All inputs are equipped with protection circuits

against static discharge and transient excess

voltage.

M74HC221

DUAL MONOSTABLE MULTIVIBRATOR

PIN CONNECTION AND IEC LOGIC SYMBOLS

ORDER CODES

PACKAGE

TUBE

T & R

DIP

M74HC221B1R

SOP

M74HC221M1R

M74HC221RM13TR

TSSOP

M74HC221TTR

TSSOP

DIP

SOP