74hct238 NXP Semiconductors, 74hct238 Datasheet - Page 2

• Manufacturer Part Number: 74hct238
• Description: 3-to-8 Line Decoder/demultiplexer
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FEATURES
GENERAL DESCRIPTION
The 74HC/HCT238 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/HCT238 decoders accept three binary
weighted address inputs (A
QUICK REFERENCE DATA
GND = 0 V; T
Notes
1. C
2. For HC the condition is V
ORDERING INFORMATION
See
December 1990
SYMBOL
t
C
C
PHL/
Demultiplexing capability
Multiple input enable for easy expansion
Ideal for memory chip select decoding
Active HIGH mutually exclusive outputs
Output capability: standard
I
3-to-8 line decoder/demultiplexer
I
PD
CC
f
f
C
V
For HCT the condition is V
i
o
“74HC/HCT/HCU/HCMOS Logic Package Information”
CC
PD
= input frequency in MHz
L
t
category: MSI
= output frequency in MHz
(C
PLH
= output load capacitance in pF
P
= supply voltage in V
is used to determine the dynamic power dissipation (P
L
D
= C
V
amb
CC
PD
PARAMETER
propagation delay
input capacitance
power dissipation capacitance per package
2
A
E
E
= 25 C; t
n
3
n
V
f
to Y
to Y
to Y
o
CC
) = sum of outputs
2
n
n
n
f
r
0
i
, A
= t
I
I
f
1
= GND to V
= GND to V
= 6 ns
, A
(C
L
2
) and when enabled,
V
CC
2
CC
CC
f
o
) where:
1.5 V
2
.
CONDITIONS
C
notes 1 and 2
provide 8 mutually exclusive active HIGH outputs
(Y
The “238” features three enable inputs: two active LOW
(E
LOW unless E
This multiple enable function allows easy parallel
expansion of the “238” to a 1-of-32 (5 lines to 32 lines)
decoder with just four “238” ICs and one inverter.
The “238” can be used as an eight output demultiplexer by
using one of the active LOW enable inputs as the data
input and the remaining enable inputs as strobes. Unused
enable inputs must be permanently tied to their
appropriate active HIGH or LOW state.
The “238” is identical to the “138” but has non-inverting
outputs.
L
D
0
1
= 15 pF; V
in W):
and E
to Y
7
).
2
) and one active HIGH (E
CC
1
= 5 V
and E
2
are LOW and E
HC
14
16
17
3.5
72
TYPICAL
74HC/HCT238
Product specification
3
). Every output will be
HCT
18
20
21
3.5
76
3
is HIGH.
UNIT
ns
ns
ns
pF
pF