Overview
The SN74LS138N is a 3-line to 8-line decoder/demultiplexer integrated circuit produced by Texas Instruments. This device is part of the Low Power Schottky (LS) family of TTL (Transistor-Transistor Logic) MSI (Medium Scale Integration) circuits. It is designed for high-performance applications, particularly in memory decoding and data-routing systems that require short propagation delay times.
The SN74LS138N features three binary select inputs and three enable inputs, which simplify cascading and data reception. It is packaged in a 16-pin PDIP (Plastic Dual In-Line Package) and operates within a temperature range of 0°C to 70°C.
Key Specifications
| Parameter | Value |
|---|---|
| Package Type | PDIP (N) |
| Pins | 16 |
| Operating Temperature Range (°C) | 0 to 70 |
| Enable Inputs | Three (2 active-low, 1 active-high) |
| Select Inputs | Three binary select inputs |
| Output Lines | Eight |
| Propagation Delay Time | Very short, suitable for high-speed applications |
| Input Type | Fully buffered inputs with high-performance Schottky diodes |
Key Features
- Designed specifically for high-speed applications such as memory decoders and data transmission systems.
- Three enable inputs to simplify cascading and/or data reception.
- Schottky-clamped for high performance and to suppress line-ringing.
- Fully buffered inputs, each representing only one normalized load to its driving circuit.
- Can be used as a demultiplexer by using an enable input as a data input.
- Capable of implementing larger decoders without external inverters (e.g., 24-line decoder without external inverters, 32-line decoder with only one inverter).
Applications
- High-performance memory decoding systems to minimize system decoding delays.
- Data-routing applications requiring very short propagation delay times.
- Demultiplexing applications where an enable input can be used as a data input.
- Cascaded decoder systems for larger decoding requirements.
Q & A
- What is the primary function of the SN74LS138N?
The SN74LS138N is a 3-line to 8-line decoder/demultiplexer, designed to decode one of eight lines based on the conditions at the three binary select inputs and the three enable inputs.
- What package types are available for the SN74LS138N?
The SN74LS138N is available in a 16-pin PDIP (Plastic Dual In-Line Package) among other package types like SOIC and SOP.
- What is the operating temperature range of the SN74LS138N?
The operating temperature range of the SN74LS138N is from 0°C to 70°C.
- How many enable inputs does the SN74LS138N have?
The SN74LS138N has three enable inputs, two of which are active-low and one that is active-high.
- What is the purpose of the Schottky diodes in the SN74LS138N?
The Schottky diodes are used to suppress line-ringing and to simplify system design, enhancing the overall performance of the device.
- Can the SN74LS138N be used as a demultiplexer?
- How does the SN74LS138N simplify cascading decoders?
The SN74LS138N simplifies cascading decoders by allowing the implementation of larger decoders without the need for external inverters or gates.
- What are some common applications of the SN74LS138N?
- Is the SN74LS138N RoHS compliant?
- Where can I find detailed datasheets for the SN74LS138N?
