M54HC191

2/13

IEC LOGIC SYMBOLS

INPUT AND OUTPUT EQUIVALENT CIRCUIT

PIN DESCRIPTION

TRUTH TABLE

X : Don’t Care

a - d: The level of steady state inputs a through d respectively

PIN N°

SYMBOL

NAME AND FUNCTION

3, 2, 6, 7

QA to QD

Flip-Flop Outputs

4

ENABLE

Count Enable Input

(Active LOW)

5D/U

Parallel Data Input

11

LOAD

Load Input (Active LOW)

12

MA/MI OUT Terminal Count Output

13

RCO

Ripple Clock Output

(Active LOW)

14

CLOCK

Clock Input (LOW to

HIGH, edge triggered)

15, 1, 10, 9

DA to DD

Data Inputs

8

GND

Ground (0V)

16

Positive Supply Voltage

INPUTS

OUTPUTS

FUNCTION

LOAD

ENABLE

D/U

CLOCK

QAQBQCQD

L

X

X

X

a

b

c

d

PRESET DATA

H

L

L

UP COUNT

UP COUNT

H

L

H

DOWN COUNT

DOWN COUNT

H

H

X

NO CHANGE

NO COUNT

H

X

X

NO CHANGE

NO COUNT