Encyclopedia Entry: 74AC257SC

Product Overview

Category

The 74AC257SC belongs to the category of integrated circuits (ICs).

Use

This IC is commonly used in digital electronic systems for data multiplexing and demultiplexing applications.

Characteristics

• The 74AC257SC is a quad 2-input multiplexer with 3-state outputs.
• It operates on a supply voltage range of 2V to 6V, making it suitable for various digital systems.
• This IC offers high-speed operation and low power consumption.
• It has a wide operating temperature range, typically from -40°C to +85°C.
• The 74AC257SC is designed to be compatible with TTL (Transistor-Transistor Logic) and CMOS (Complementary Metal-Oxide-Semiconductor) logic levels.

Package and Quantity

The 74AC257SC is available in a small outline package (SOIC) with 16 pins. It is commonly sold in reels or tubes containing multiple units.

Essence

The essence of the 74AC257SC lies in its ability to efficiently multiplex and demultiplex data signals in digital systems.

Specifications

• Supply Voltage Range: 2V to 6V
• Operating Temperature Range: -40°C to +85°C
• Input Voltage High (VIH): 2V to VCC
• Input Voltage Low (VIL): GND to 0.8V
• Output Voltage High (VOH): VCC - 0.5V
• Output Voltage Low (VOL): 0.4V
• Propagation Delay Time: 7 ns (max)
• Power Dissipation: 500 mW (max)

Detailed Pin Configuration

The 74AC257SC has a total of 16 pins, each serving a specific purpose. The pin configuration is as follows:

1. A0: Input A0
2. B0: Input B0
3. A1: Input A1
4. B1: Input B1
5. GND: Ground
6. Y0: Output Y0
7. Y1: Output Y1
8. E: Enable Input
9. Y2: Output Y2
10. Y3: Output Y3
11. B3: Input B3
12. A3: Input A3
13. B2: Input B2
14. A2: Input A2
15. VCC: Supply Voltage
16. NC: No Connection

Functional Features

The 74AC257SC offers the following functional features:

• Quad 2-input multiplexer with 3-state outputs.
• Enables data selection from four different inputs (A0-A3, B0-B3) based on the control input (E).
• Provides four output lines (Y0-Y3) for transmitting the selected data.

Advantages and Disadvantages

Advantages

• High-speed operation allows for efficient data multiplexing and demultiplexing.
• Low power consumption makes it suitable for battery-powered devices.
• Wide operating temperature range enables usage in various environments.
• Compatibility with TTL and CMOS logic levels ensures versatility in system integration.

Disadvantages

• Limited number of input and output lines may restrict its application in complex systems.
• Propagation delay time may affect real-time applications requiring instantaneous data transmission.

Working Principles

The 74AC257SC operates by selectively routing data from the input lines (A0-A3, B0-B3) to the output lines (Y0-Y3) based on the control input (E). When E is low, the outputs are in a high-impedance state, allowing multiple devices to share the same bus without interference. When E is high, the selected input data is transmitted to the corresponding output line.

Detailed Application Field Plans

The 74AC257SC finds applications in various digital systems, including but not limited to:

1. Data multiplexing and demultiplexing in microcontrollers and microprocessors.
2. Address decoding in memory systems.
3. Signal routing in communication devices.
4. Input/output expansion in embedded systems.
5. Logic circuit design in electronic projects.

Alternative Models

For similar functionality, the following alternative models can be considered:

1. 74HC257: CMOS logic level compatible version.
2. 74LS257: TTL logic level compatible version.
3. CD4051: Analog multiplexer/demultiplexer IC.

These alternative models provide comparable features and can be used as substitutes for the 74AC257SC in different applications.

In conclusion, the 74AC257SC is a versatile integrated circuit used for data multiplexing and demultiplexing in digital systems. Its high-speed operation, low power consumption, and compatibility with