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Product data sheet

Rev. 03 — 20 April 2005

5 of 19

Philips Semiconductors

74ABT544

Octal latched transceiver with dual enable; inverting; 3-state

7.

Functional description

7.1 Function table

[1]

H = HIGH voltage level;

h = HIGH voltage level one set-up time prior to the LOW-to-HIGH clock transition;

L = LOW voltage level;

l = LOW voltage level one set-up time prior to the LOW-to-HIGH clock transition;

X = don’t care;

↑ = LOW-to-HIGH clock transition;

NC = no change;

Z = high-impedance OFF-state.

B3

19

port B, 3-state output 3

B2

20

port B, 3-state output 2

B1

21

port B, 3-state output 1

B0

22

port B, 3-state output 0

EBA

23

B-to-A enable input (active LOW)

24

supply voltage

Table 3:

Symbol

Pin

Description

Table 4:

Function table [1]

Status

Control

Input

Output

OExx

Exx

LExx

An or Bn

An or Bn

Disabled

H

XXXZ

XH

XXZ

Disabled + latch

L

↑

LhZ

lZ

Latch + display

L

L

↑

hL

lH

Transparent

LLLH

L

LH

Hold

L

L

H

X

NC