SN74HC251DBR

Overview

The SN74HC251DBR is an 8-to-1 data selector/multiplexer from the Texas Instruments HC series, housed in a 16-pin SSOP package. It features full binary decoding to select one of eight data sources and provides strobe-controlled complementary 3-state outputs. The device operates within a supply voltage range of 2 V to 6 V and supports an operating temperature range of -40°C to +85°C. Key electrical characteristics include a maximum input current of 1 μA, typical propagation delay of 9 ns at 5 V with 50 pF load, and output drive capability of ±6 mA at 5 V.

Feature Summary

• Provides 1-of-8 data selection with full binary decoding logic
• Features complementary true and inverted 3-state outputs controlled by a strobe input
• Capable of parallel-to-serial conversion functions
• Outputs interface directly with system buses or drive multiple LSTTL loads

Applications

• Bus-oriented system data routing
• Parallel-to-serial data conversion circuits
• Data selector applications requiring high-impedance bus isolation

Procurement Notes

Verify that the specific orderable part number matches the required package type and tape/reel quantity specifications. Confirm RoHS compliance status and moisture sensitivity level ratings for surface mount assembly processes. Ensure the procurement documentation aligns with the active production status indicated in the manufacturer's latest package addendum.

Selection Notes

Select this component when an 8-channel multiplexer with tri-state output control is required for standard CMOS logic interfaces. Consider the wide operating voltage range and low power consumption characteristics suitable for battery-powered or general-purpose digital systems. Verify thermal resistance requirements against the SSOP package junction-to-ambient rating for the intended application environment.

Part Context

This device belongs to the SNx4HC251 family of data selectors, which are functionally equivalent to the 3-state version of the SN74HC151. It is part of the broader Texas Instruments 74HC series of high-speed CMOS logic devices designed for general-purpose digital applications.

Replacement Considerations

SN74HC251DR (SOIC package)

FAQ

How are the outputs controlled?

The complementary 3-state outputs are controlled by the output-enable (OE) input. Outputs are disabled when OE is high.

What happens if inputs are left floating?

Unused inputs must not be left floating; they should be connected to logic high or logic low voltage to prevent undefined operational states.