Overview
The SN74ALS138A is a 3-line to 8-line decoder/demultiplexer produced by Texas Instruments. This integrated circuit is designed for high-performance memory-decoding or data-routing applications. It features a Schottky-clamped system that minimizes system delay, making it suitable for various digital systems. The device operates over a temperature range of 0°C to 70°C, ensuring reliability in a variety of environmental conditions.
Key Specifications
| Parameter | Unit | Min | Nom | Max |
|---|---|---|---|---|
| VCC Supply Voltage | V | 4.5 | 5 | 5.5 |
| VIH High-level Input Voltage | V | 2 | 2 | |
| VIL Low-level Input Voltage | V | 0.7 | 0.8 | 0.8 |
| IOH High-level Output Current | mA | -0.4 | -0.4 | |
| IOL Low-level Output Current | mA | 4 | 8 | |
| TA Operating Free-air Temperature | °C | 0 | 70 | |
| VOH High-level Output Voltage | V | VCC - 2 | VCC - 2 | |
| VOL Low-level Output Voltage | V | 0.25 | 0.4 | 0.5 |
Key Features
- 3-Line to 8-Line Decoding/Demultiplexing: The SN74ALS138A can select one of eight output lines based on the conditions at the binary-select (A, B, and C) inputs and the three enable (G1, G2A, and G2B) inputs.
- Enable Inputs: Two active-low and one active-high enable inputs reduce the need for external gates or inverters when expanding the decoder.
- Demultiplexing Capability: An enable input can be used as a data input for demultiplexing applications.
- Temperature Range: Operates over a temperature range of 0°C to 70°C, ensuring reliability in various environmental conditions.
- Low System Delay: The Schottky-clamped system introduces negligible system delay, making it suitable for high-performance applications).
Applications
- Memory Decoding: Ideal for memory-decoding applications where high performance and low delay are critical).
- Data Routing: Suitable for data-routing applications where multiple output lines need to be selected based on input conditions).
- Digital Systems: Can be used in various digital systems requiring efficient decoding and demultiplexing functions).
Q & A
- What is the primary function of the SN74ALS138A?
The SN74ALS138A is a 3-line to 8-line decoder/demultiplexer designed for high-performance memory-decoding or data-routing applications).
- What is the operating temperature range of the SN74ALS138A?
The SN74ALS138A operates over a temperature range of 0°C to 70°C).
- How many enable inputs does the SN74ALS138A have?
The SN74ALS138A has three enable inputs: two active-low (G2A, G2B) and one active-high (G1)).
- Can the SN74ALS138A be used for demultiplexing?
- What is the supply voltage range for the SN74ALS138A?
The supply voltage range for the SN74ALS138A is 4.5V to 5.5V).
- How many output lines can the SN74ALS138A select?
The SN74ALS138A can select one of eight output lines based on the input conditions).
- Is the SN74ALS138A still in production?
No, the SN74ALS138ANS is no longer manufactured and will no longer be stocked once the current stock is depleted).
- What are the typical high-level and low-level output currents for the SN74ALS138A?
The typical high-level output current is -0.4 mA, and the typical low-level output current is 4 mA to 8 mA).
- Can the SN74ALS138A be used to implement larger decoders?
- What is the significance of the Schottky-clamped system in the SN74ALS138A?
The Schottky-clamped system introduces negligible system delay, enhancing the device's performance in high-speed applications).
