TRUTH TABLE

INPUTS

OUTPUTS

FUNCTION

CCLR LOAD

ENP

ENT

CCK

U/D

RCK

R/C

G

QA

QB

QC

QD

X

X

X

X

X

X

X

X

H

ZZZZ

HIGH IMPEDANCE

L

X

X

X

X (*)

X

X

L

L

L

L

L

L

CLEAR COUNTER

H

L

X

X

X

X

L

L

a

b

c

d

LOAD COUNTER

H

H

H

X

X

X

L

L

NO CHANGE

NO COUNT

H

H

X

H

X

X

L

L

NO CHANGE

NO COUNT

H

H

L

L

H

X

L

L

COUNT UP

COUNT UP

H

H

L

L

L

X

L

L

COUNT DOWN

COUNT DOWN

H

X

X

X

X

X

L

L

NO CHANGE

NO COUNT

X

X

X

X

X

X

H

L

a’

b’

c’

d’

LOAD REGISTER

X

X

X

X

X

X

H

L

NO CHANGE

NO LOAD

(*)

:

For HC698/699

X

: Don’t care

Z

: High impedance

a-d

: The level of steady state input at inputs a through D respectively

a’-d’

: The level of steady state outputs at internal counter outputs QA’ through QD’ respectively

RCO function : HC696/8 - RCO = (UP

• QA • QD • ENT + UP • QA • QD • ENT)

HC697/9 - RCO = (UP

• QA • QB • QC • QD • ENT + UP • QA • QB • QC • QD • ENT)

BLOCK DIAGRAM

M54/M74HC696/697/698/699

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