74HC158 datasheet(2/7 Pages) PHILIPS

2 / 7 page

December 1990

Philips Semiconductors

Product speciﬁcation

Quad 2-input multiplexer; inverting

74HC/HCT158

FEATURES

• Inverting data path

• Output capability: standard

• ICC category: MSI

GENERAL DESCRIPTION

The 74HC/HCT158 are high-speed Si-gate CMOS devices

and are pin compatible with low power Schottky TTL

(LSTTL). They are specified in compliance with JEDEC

standard no. 7A.

The 74HC/HCT158 are quad 2-input multiplexers which

select 4 bits of data from two sources and are controlled by

a common data select input (S). The four outputs present

the selected data in the inverted form. The enable input (E)

is active LOW.

When E is HIGH, all the outputs (1Y to 4Y) are forced

HIGH regardless of all other input conditions.

Moving the data from two groups of registers to four

common output buses is a common use of the “158”. The

state of S determines the particular register from which the

data comes. It can also be used as a function generator.

The device is useful for implementing highly irregular logic

by generating any four of the 16 different functions of two

variables with one variable common.

The ”158” is the logic implementation of a 4-pole,

2-position switch, where the position of the switch is

determined by the logic levels applied to S.

The logic equations for the output are:

1Y = E.(1l1.S + 1l0.S)

2Y = E.(2l1.S + 2l0.S)

3Y = E.(3l1.S + 3l0.S)

4Y = E.(4l1.S + 4l0.S)

The “158” is identical to the “157” but has inverting outputs.

QUICK REFERENCE DATA

GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns

Notes

1. CPD is used to determine the dynamic power dissipation (PD in µW):

PD = CPD × VCC2 × fi +∑ (CL × VCC2 × fo) where:

fi = input frequency in MHz

fo = output frequency in MHz

∑ (CL × VCC2 × fo) = sum of outputs

CL = output load capacitance in pF

VCC = supply voltage in V

2. For HC the condition is VI = GND to VCC

For HCT the condition is VI = GND to VCC − 1.5 V

ORDERING INFORMATION

See

“74HC/HCT/HCU/HCMOS Logic Package Information”.

SYMBOL

PARAMETER

CONDITIONS

TYPICAL

UNIT

HCT

tPHL/ tPLH

propagation delay

CL = 15 pF; VCC = 5 V

nI0, nI1 to nY

E to nY14

S to nY14

input capacitance

3.5

CPD

power dissipation capacitance per multiplexer

notes 1 and 2

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