Unit LoadingFan Out

54F74F

Pin Names

Description

UL

HIGHLOW

S

Common Data Select Input

1010

OE

TRI-STATE Output Enable Input (Active LOW)

1010

Data Inputs from Source 0

1010

Data Inputs from Source 1

1010

TRI-STATE Inverting Data Outputs

15040 (333)

b

3 mA24 mA (20 mA)

Functional Description

The ’F258A is a quad 2-input multiplexer with TRI-STATE

outputs It selects four bits of data from two sources under

control of a common Select input (S) When the Select input

inputs appears at the outputs in inverted form The ’F258A

is the logic implementation of a 4-pole 2-position switch

where the position of the switch is determined by the logic

levels supplied to the Select input The logic equation for

the outputs is shown below

When the Output Enable input (OE) is HIGH the outputs are

forced to a high impedance OFF state If the outputs of the

TRI-STATE devices are tied together all but one device

must be in the high impedance state to avoid high currents

that would exceed the maximum ratings Designers should

ensure that Output Enable signals to TRI-STATE devices

whose outputs are tied together are designed so there is no

overlap

Truth Table

Output

Select

Data

Output

Enable

Input

Inputs

OE

Z

HX

X

X

Z

LH

X

L

H

LH

X

H

L

LL

L

X

H

LL

H

X

L

Logic Diagram

TLF9508 – 4

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays

2