74HC138

3-to-8 Line Decoder/Demultiplexer

DIP-16 2V – 6V Datasheet ↗

Pinout

74HC138A01A12A23~E14~E25E36~Y77GND8~Y69~Y510~Y411~Y312~Y213~Y114~Y015VCC16

Description

The 74HC138 is a high-speed CMOS 3-to-8 line decoder/demultiplexer. It accepts a 3-bit binary address on inputs A0–A2 and activates one of eight active-low outputs (Y0–Y7). Three enable inputs (E1, E2 active-low, E3 active-high) allow cascading and easy expansion to larger decoders.

Pin Descriptions

#NameTypeDescription
1A0inputAddress input bit 0 (LSB)
2A1inputAddress input bit 1
3A2inputAddress input bit 2 (MSB)
4~E1enableEnable input 1, active low
5~E2enableEnable input 2, active low
6E3enableEnable input 3, active high
7~Y7outputOutput 7, active low
8GNDpowerGround
9~Y6outputOutput 6, active low
10~Y5outputOutput 5, active low
11~Y4outputOutput 4, active low
12~Y3outputOutput 3, active low
13~Y2outputOutput 2, active low
14~Y1outputOutput 1, active low
15~Y0outputOutput 0, active low (selected when A=000)
16VCCpowerSupply voltage

Truth Table

E1~E2~E3A2A1A0Y0~Y1~Y2~Y3~Y4~Y5~Y6~Y7~
HXXXXXHHHHHHHH
XHXXXXHHHHHHHH
XXLXXXHHHHHHHH
LLHLLLLHHHHHHH
LLHLLHHLHHHHHH
LLHLHLHHLHHHHH
LLHLHHHHHLHHHH
LLHHLLHHHHLHHH
LLHHLHHHHHHLHH
LLHHHLHHHHHHLH
LLHHHHHHHHHHHL