74LS257 DIP Quad 2-Line to 1-Line Data Selector/Multiplexer with 3-State Outputs

The 74LS257 is a high speed TTL integrated circuit containing four independent 2-line to 1-line data selectors/multiplexers. It is designed to select one of two 4-bit words and route it to a common 4-bit output bus. A single Select input determines which of the two data sets (A or B) is presented at the outputs. This makes the device exceptionally useful for selecting between different data sources, such as address or data paths in a microprocessor system.

The device features 3-state outputs that are controlled by a common Output Enable (G) input. When the enable input is low, the selected data is presented at the outputs; when high, the outputs enter a high-impedance state. This high-impedance capability allows the 74LS257 to interface directly with bus-organized systems, as multiple outputs can be tied to the same bus without interference. Its low power Schottky architecture provides the high speed required for real-time data switching with low power consumption.

KEY FEATURES

• Four independent 2-line to 1-line multiplexers in one package
• 3-state outputs for direct bus-oriented system interfacing
• Common Select and Output Enable inputs for simplified control
• Non-inverting data paths for straightforward logic implementation
• Low power Schottky technology for high speed and efficiency
• Standard 16 pin dual in line package

SPECIFICATIONS

• Supply Voltage 4.75V to 5.25V
• Operating Temperature 0 to 70 Celsius
• Logic Type TTL Low Power Schottky
• Typical Propagation Delay 12ns
• High Level Output Current -2.6mA
• Low Level Output Current 24mA
• Input Voltage High 2.0V Minimum

INTERFACES

• 1A to 4A Data inputs group A
• 1B to 4B Data inputs group B
• SEL Select input (Low selects A, High selects B)
• OE BAR Output enable input active low
• 1Y to 4Y 3-state multiplexer outputs
• VCC Positive supply voltage
• GND Ground reference