M74HC259

2/13

INPUT AND OUTPUT EQUIVALENT CIRCUIT

PIN DESCRIPTION

TRUTH TABLE

D : The level at the data input

Qi0 : The level before the indicated steady state input conditions where established, (i = 0, 1, ......., 7).

PIN No

SYMBOL

NAME AND FUNCTION

1, 2, 3

A, B, C

Address Inputs

4, 5, 6, 7, 9,

10, 11, 12

Q0 to Q7

Latch Outputs

13

D

Data Input

14

ENABLE

Latch Enable Input (Active

Low)

15

CLEAR

Conditional Reset Input

(Low)

8

GND

Ground (0V)

16

Vcc

Positive Supply Voltage

INPUTS

OUTPUTS OF

ADDRESSED LATCH

EACH OTHER OUTPUT

FUNCTION

CLEAR

ENABLE

H

L

D

Qi0

ADDRESSABLE LATCH

H

H

Qi0

Qi0

MEMORY

L

L

D

L

8 LINE DEMULTIPLEXER

LH

L

L

CLEAR ALL BITS TO ’L’

SELECT INPUTS

LATCH ADDRESSED

CBA

LLL

Q0

LL

H

Q1

LHL

Q2

LH

H

Q3

HL

L

Q4

HLH

Q5

HH

L

Q6

HHH

Q7