Datasheet

SN54HC138, SN74HC138
3-LINE TO 8-LINE DECODERS/DEMULTIPLEXERS
SCLS107E − DECEMBER 1982 − REVISED SEPTEMBER 2003
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description/ordering information (continued)
The conditions at the binary-select inputs at the three enable inputs select one of eight output lines. Two
active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding.
A 24-line decoder can be implemented without external inverters, and a 32-line decoder requires only one
inverter. An enable input can be used as a data input for demultiplexing applications.
FUNCTION TABLE
INPUTS
OUTPUTS
ENABLE SELECT
OUTPUTS
G1 G2A G2B C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
X H X X X X H H H H H H H H
X XHXXXHHHHHHHH
L XXXXXHHHHHHHH
H LLLLLLHHHHHHH
H LLLLHHLHHHHHH
H LLLHLHHLHHHHH
H LLLHHHHHLHHHH
H LLHLLHHHHLHHH
H LLHLHHHHHHLHH
H LLHHLHHHHHHLH
H L L H H H H H H H H H H L