74139 Dual 2-to-4 Line Decoder / Demultiplexer IC

The 74139 is a dual 2 ? 4 line decoder with a demultiplexer in the 7400 series. Each side of the IC is a decoder with an active low enable from a 2-bit address to four active low signals. The two decoders can be wired independently or a /Y from one decoder can be wired to the /E on the other to calculate more complex combinational logic functions.

Specifications:

Parameter

Value

Unit

Propagation delay nAn to nYn

11 (74HC)

13 (74HCT)

ns

Propagation delay nE to nYn

10 (74HCT)

13 (74HCT)

ns

Pin Description

Pin

Symbol

Description

1

1E

enable input (active low)

2

1A0

address input

<td>3

1A1

address input

4

1Y0

output (active low)

5

1Y1

output (active low)

6

1Y2

output (active low)

7

1Y3

output (active low)

<td>8

GND

ground

9

2Y3

output (active low)

10

2Y2

Output (active low)

11

2Y1

output (active low)

12

2Y0

output (active low)

13

2A1

address input

14

2A0

address input

15

2E

enable input (active low)

16

Vcc

supply voltage