INPUT AND OUTPUT EQUIVALENT CIRCUIT

LOGIC DIAGRAMS

PIN DESCRIPTION

PIN No

SYMBOL

NAME AND F UNCTIO N

1

SELECT

Common Data Select Input

2, 5, 14, 11

1A to 4A

Data Input From Source A

3, 6, 13, 10

1B to 4B

Data Inputs from Source B

4, 7, 12, 9

1Y to 4Y

3 State Multiplexer Outputs

15

OE

3 State Output Enable

Inputs (Active LOW)

8

GND

Ground (0V)

16

Positive Supply Voltage

TRUTH TABLE

INPUTS

OUTPUT S

O E

SELECT

ABY

H

X

XXZ

LLL

X

L

LL

H

X

H

LH

X

L

L

LH

X

H

H

X = DON’T CARE Z = HIGH IMPEDANCE

This logic diagram has not be used to estimate propagation delays

74ACT257

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