74LS138 3-to-8 Decoder – DIP-16

The 74138 is a TTL logic integrated circuit designed to convert 3 binary input lines into 8 mutually exclusive active-low outputs. It performs one-of-eight decoding, where only one output is activated based on the input combination. The device includes three enable inputs (two active-low and one active-high), allowing flexible control and easy cascading for larger decoding systems. Operating on a standard 5V TTL supply, the 74138 is widely used in address decoding, memory selection, signal routing, and digital control applications.

Features

- 3-to-8 line decoder architecture

- One-of-eight output decoding

- Active-low output configuration

- Three enable inputs for flexible control

- Supports cascading for larger decoder systems

- Standard TTL logic compatibility

- Single 5V supply operation

- Fast switching performance

- Suitable for memory and address decoding

- Can function as a demultiplexer

- Reliable digital logic operation

- DIP-16 through-hole package

- Breadboard-friendly design

- Easy PCB integration

Specifications

Model: 74138

Device Type: 3-Line to 8-Line Decoder / Demultiplexer IC

Logic Family: TTL

Input Lines: 3

Output Lines: 8 (Active-Low)

Enable Inputs: 3 (2 Active-Low, 1 Active-High)

Supply Voltage: 5V

Propagation Delay (Typical): 15ns

Maximum Output Sink Current: 16mA

Power Consumption (Typical): 75mW

Package Type: 16-Pin DIP

Mounting Type: Through-Hole

Operating Temperature Range: 0°C to +70°C

Application Type: Address Decoding and Signal Routing

Links

- 3D Model

- Datasheet

Tutorials

Decoder: 3:8 74138 Decoder IC