The MC54LS138J is a 3-to-8 Line Decoder/Demultiplexer. Belonging to the LS (Low-power Schottky) TTL family, this device decodes one of eight lines based on a 3-bit binary input. It features three enable inputs to facilitate cascading and is commonly used in memory addressing, data routing, and control signal distribution.

Applications

• Memory address decoding
• Data routing
• Control signal selection
• Peripheral selection
• Industrial control systems

Features

• 3-to-8 line decoding
• Low-power Schottky TTL technology
• Three enable inputs
• High noise immunity
• Typical propagation delay of 20 ns
• Fan-out of 10 LS-TTL loads

Benefits

• Efficient memory addressing
• Simplified data routing
• Flexible control signal selection
• Reduced component count
• Improved system reliability

The MC54LS138J operates from a standard 5V power supply. It has three enable inputs (G1, G2A, G2B), allowing for selective activation of the decoder. When the enable inputs are active, one of the eight output lines is asserted low, corresponding to the binary input code applied to the A, B, and C inputs.

The internal circuitry consists of TTL gates, providing a good balance between speed and power consumption. The device's low-power Schottky technology reduces power dissipation and improves noise immunity compared to standard TTL devices.

The MC54LS138J is typically available in a 16-pin DIP (Dual In-line Package). It is designed to operate over a military temperature range, typically -55°C to 125°C.

This decoder/demultiplexer is suitable for various applications where efficient memory addressing or control signal selection is required. Its ease of use and versatile features make it a popular choice for designers of digital systems, computer systems, and industrial control systems.