December 1990 2
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
• I
CC
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 (I
0
to I
8
) 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; T
amb
=25°C; t
r
=t
f
= 6 ns
Notes
1. C
PD
is used to determine the dynamic power dissipation (P
D
in µW):
P
D
=C
PD
× V
CC
2
× f
i
+∑(C
L
× V
CC
2
× f
o
) where:
f
i
= input frequency in MHz
f
o
= output frequency in MHz
∑ (C
L
× V
CC
2
× f
o
) = sum of outputs
C
L
= output load capacitance in pF
V
CC
= supply voltage in V
2. For HC the condition is V
I
= GND to V
CC
For HCT the condition is V
I
= GND to V
CC
− 1.5 V
ORDERING INFORMATION
See
“74HC/HCT/HCU/HCMOS Logic Package Information”
.
SYMBOL PARAMETER CONDITIONS
TYPICAL
UNIT
HC HCT
t
PHL
/ t
PLH
propagation delay C
L
= 15 pF; V
CC
=5 V
I
n
to ∑
E
17 18 ns
I
n
to ∑
O
20 22 ns
C
I
input capacitance 3.5 3.5 pF
C
PD
power dissipationcapacitance per package notes 1 and 2 65 65 pF
