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 (74HC) 13 (74HCT) |
ns |
Pin Description :
Pin | Symbol | Description |
---|---|---|
1 | 1E | enable input (active low) |
2 | 1A0 | address input |
3 | 1A1 | address input |
4 | 1Y0 | output (active low) |
5 | 1Y1 | output (active low) |
6 | 1Y2 | output (active low) |
7 | 1Y3 | output (active low) |
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 |
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