CD74HC257EX

Overview

The CD74HC257EX is a high-speed CMOS logic device manufactured by Harris Corporation, belonging to the HC/UH series. It functions as a quad 2-input multiplexer with three-state non-inverting outputs. The component utilizes a 16-pin PDIP package and operates within a temperature range of -55 °C to 125 °C. It features an enable input for controlling output states and includes clamp diodes on inputs to facilitate interface with voltages exceeding VCC using current-limiting resistors.

Feature Summary

• Quad 2-input multiplexer architecture providing four independent data selection channels
• Three-state outputs allowing direct interfacing with system buses
• Non-inverting data path ensuring true output form from selected inputs
• Input clamp diodes included for protection against voltage exceedances

Applications

• Data selection between two sources in digital systems
• Interface buffering for system bus connections
• Multiplexing applications requiring tri-state control

Procurement Notes

Verify manufacturer documentation for specific ordering suffixes and package variations. Confirm RoHS compliance status as historical Harris components may differ from modern standards. Ensure the PDIP-16 package matches design requirements. Check for obsolescence notices or lifecycle changes associated with Harris Corporation logic products before finalizing procurement plans.

Selection Notes

Select this component when a quad 2-input multiplexer with tri-state capability is required. The HC series offers compatibility with standard CMOS logic levels. Consider the operating temperature range and package type for environmental suitability. Verify that the non-inverting output characteristic aligns with the circuit design needs compared to inverted alternatives.

Part Context

This part belongs to the widely used 74HC logic family, known for high-speed CMOS operation. It is pin-compatible with Low-power Schottky TTL (LSTTL) devices, facilitating upgrades in legacy designs. The CD prefix typically denotes commercial grade temperature ranges, while the E suffix often indicates specific packaging or testing configurations defined by the manufacturer.

Replacement Considerations

Compatible substitutes include the NXP 74HC257 and Texas Instruments CD74HC257. These parts share identical logical functionality and pinouts. Verify supply voltage ranges and output drive capabilities to ensure interchangeability in existing circuits.