HD74HC138 Datasheet, PDF (1/9 Pages) Hitachi Semiconductor – 3-to-8-line Decoder/Demultiplexer

HD74HC138
3-to-8-line Decoder/Demultiplexer
Description
The HD74HC138 has 3 binary select inputs (A, B and C). If the device is enabled these inputs determine
which one of the eight normally high outputs will go low. Two active low and one active high enables (G₁,
G_2A and G_2B) are provided to ease the cascading of decoders.
Features
• High Speed Operation: t_pd (A, B, C to Y) = 16.5 ns typ (C_L = 50 pF)
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: V_CC = 2 V to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: I_CC (static) = 4 µA max (Ta = 25°C)
Function Table
Inputs
Enable
Select
Outputs
G1 G_2A
G_2B
C
B
A
Y₀
Y₁
Y₂
Y₃
Y₄
Y₅
Y₆
Y₇
XX
H
X
X
X
H
H
H
H
H
H
H
H
XH
X
X
X
X
H
H
H
H
H
H
H
H
LX
X
X
X
X
H
H
H
H
H
H
H
H
HL
L
L
L
L
L
H
H
H
H
H
H
H
HL
L
L
L
H
H
L
H
H
H
H
H
H
HL
L
L
H
L
H
H
L
H
H
H
H
H
HL
L
L
H
H
H
H
H
L
H
H
H
H
HL
L
H
L
L
H
H
H
H
L
H
H
H
HL
L
H
L
H
H
H
H
H
H
L
H
H
HL
L
H
H
L
H
H
H
H
H
H
L
H
HL
L
H
H
H
H
H
H
H
H
H
H
L