74139.md

74139: dual 2-bit to 4-line decoder

• Type: decoder
• DIP: 16-pin
• Input: 2-bit
• Output: 4 lines

Description

This chip provides two 2-bit to four line decoders with active low output.

Inputs and outputs

Label	Description	Signal
An	encoded input of first decoder	active high
Bn	encoded input of second decoder	active high
Yn	output of first decoder	active low
Zn	output of second decoder	active low
OEA	output enable of first decoder	active low
OEB	output enable of second decoder	active low

Function table

OEA	A1	A0	Y3	Y2	Y1	Y0
H	X	X	X	X	X	H
L	L	L	H	H	H	L
L	L	H	H	H	L	H
L	H	L	H	L	H	H
L	H	H	L	H	H	H

OEB	B1	B0	Z3	Z2	Z1	Z0
H	X	X	X	X	X	H
L	L	L	H	H	H	L
L	L	H	H	H	L	H
L	H	L	H	L	H	H
L	H	H	L	H	H	H

• H: HIGH voltage level
• L: LOW voltage level
• X: don't care

Pin layout

Datasheets

• CD74HC139 by Texas Instruments
• 74HC139 74HCT139 by Nexperia