HD74HC148

8-to-3-line Octal Priority Encoder

Description

The HD74HC148 encodes eight data lines to three-line (4-2-1) binary (octal). Cascading circuitry (enable

input EI and enable output EO) is provided to allow octal expansion without the need for external circuitry.

The data inputs and outputs are active at the low logic level.

Features

• High Speed Operation: t

• High Output Current: Fanout of 10 LSTTL Loads

• Wide Operating Voltage: V

• Low Input Current: 1 µA max

• Low Quiescent Supply Current: I

Function Table

Inputs

Outputs

EI

012

345

67A

2

A

1

A

0

GS

EO

H

XXX

XXX

XXH

H

H

H

H

L

HHH

HHH

HHH

HHH

L

L

XXX

XXX

XL

LL

L

L

H

L

XXX

XXX

L

H

LL

H

L

H

L

XXX

XXLH

H

L

H

L

LH

L

X

X

X

X

L

H

HHL

HHL

H

L

X

X

X

LH

H

H

H

H

LLL

H

L

X

X

L

HHH

HHH

L

H

L

H

L

X

L

H

HHH

HHH

HL

L

H

L

L

HH

HHH

HHH

HHL

H

H :

High level

L

:

Low level

X :

Irrelevant