74HCT280 datasheet(2/7 Pages) PHILIPS

2 / 7 page

December 1990

Philips Semiconductors

Product speciﬁcation

9-bit odd/even parity generator/checker

74HC/HCT280

FEATURES

• Word-length easily expanded by cascading

• Similar pin configuration to the “180” for easy system

up-grading

• Generates either odd or even parity for nine data bits

• Output capability: standard

• ICC category: MSI

GENERAL DESCRIPTION

The 74HC/HCT280 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/HCT280 are 9-bit parity generators or checkers

commonly used to detect errors in high-speed data

transmission or data retrieval systems. Both even and odd

parity outputs are available for generating or checking

even or odd parity up to 9 bits.

The even parity output (

∑E) is HIGH when an even number

of data inputs (I0 to I8) are HIGH. The odd parity output (∑0)

is HIGH when an odd number of data inputs are HIGH.

Expansion to larger word sizes is accomplished by tying

the even outputs (

∑E) of up to nine parallel devices to the

data inputs of the final stage. For a single-chip 16-bit

even/odd parity generator/checker, see

PC74HC/HCT7080.

APPLICATIONS

• 25-line parity generator/checker

• 81-line parity generator/checker

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

In to ∑E

In to ∑O

input capacitance

3.5

CPD

power dissipationcapacitance per package

notes 1 and 2

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