SN74HCT257D

Overview

The SN74HCT257D is a quadruple 2-line to 1-line data selector/multiplexer with 3-state outputs manufactured by Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and features buffered inputs and outputs. The device provides high-current 3-state outputs capable of driving system buses directly, with an output drive of ±6 mA at 5 V. Typical propagation delay is 17 ns, and maximum input current is 1 µA. It is housed in a 16-pin SOIC package.

Feature Summary

• Provides bus interface from multiple sources in high-performance systems
• High-current 3-state outputs interface directly with system bus
• Inputs are TTL-voltage compatible

Applications

• Multiplexing signals from 4-bit data sources to 4-output data lines
• Bus-organized systems requiring signal selection
• Data selectors for digital logic circuits

Procurement Notes

Verify the specific ordering suffix 'D' corresponds to the SOIC-16 package variant. Confirm RoHS compliance status and lead finish details via the manufacturer's official documentation or packaging addendum before procurement. Ensure the component meets the required operating temperature range of -40°C to +85°C for your application environment.

Selection Notes

Select this component when TTL-compatible inputs are required alongside CMOS performance levels. The HCT series ensures compatibility with standard TTL logic families while offering low power consumption. Verify that the 3-state output capability aligns with the bus architecture requirements of the target design.

Part Context

This part belongs to the SN74HCT257 family of quadruple 2-to-1 multiplexers. It shares functional characteristics with other variants such as SN74HCT257N (PDIP) and SN74HCT257DR (SOIC tape and reel). The 'D' suffix specifically denotes the surface-mount SOIC package format.

Replacement Considerations

SN74HCT257N

FAQ

What is the typical propagation delay for the SN74HCT257D?

The typical propagation delay (tpd) is 17 ns.

How does the OE input affect the output state?

When the Output Enable (OE) input is high, the outputs enter a high-impedance state. When OE is low, the selected data input is passed to the output.