Texas Instruments SN74LVC257AQDREP

Overview

SN74LVC257AQDREP from Texas Instruments is a radiation-hardened, quad 2-line to 1-line data selector/multiplexer with 3-state outputs, designed for 2.0–3.6 V operation in extended-temperature aerospace and defense systems. It features 4.6 ns max propagation delay at 3.3 V, 5.5 V-tolerant inputs, and operates across –40°C to 125°C. Its 3-state outputs enable bus-oriented multiplexing in mixed-voltage (3.3 V/5 V) digital subsystems.

For engineers reviewing the SN74LVC257AQDREP datasheet, SN74LVC257AQDREP pinout, SN74LVC257AQDREP application, or SN74LVC257AQDREP equivalent, key selection criteria include its 16-pin SOIC-D package, OE-controlled 3-state output behavior, voltage translation capability, and QML-qualified reliability for high-integrity embedded timing and control paths.

Technical Context

This device implements four independent 2:1 multiplexers sharing a common output-enable (OE) input. Each channel selects between two data inputs (A/B) based on the A/B select line, routing the chosen signal to a 3-state output (Y). All logic is LVC-family CMOS, ensuring rail-to-rail swing and low static current.

Input tolerance up to 5.5 V enables direct interfacing with legacy 5-V logic without level shifters. The 3-state outputs are actively disabled when OE is high, presenting high impedance (>10⁹ Ω) to downstream buses - critical for shared-data-path architectures in avionics and spaceborne telemetry interfaces.

Key Specifications

Pinout & Package

SN74LVC257AQDREP is housed in a 16-pin SOIC-D package (7.5 mm × 10.3 mm, 1.75 mm height), JEDEC MS-012 compliant, with 1.27 mm pitch and gull-wing leads. RoHS-compliant matte tin lead finish, MSL Level 1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.

Compared with SN74LVC257AQDREP, SN74LVC257AQPWREP offers smaller footprint and higher thermal resistance, while SN54LVC257A provides deeper military screening - neither is pin-compatible without layout revision due to differing package footprints and marking conventions.

Availability

SN74LVC257AQDREP is available at Aetrix Electronics and suitable for avionics data bus multiplexing, satellite telemetry interface, and industrial PLC I/O expansion requiring stable component supply across extended temperature and radiation environments.

Supply support for SN74LVC257AQDREP includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-reliability components for aerospace, industrial, and automotive markets.

The SN74LVC257A-EP product line delivers radiation-tolerant, extended-temperature logic ICs for mission-critical systems where failure is not an option - designed specifically for satellite payloads, flight computers, and hardened ground stations.

FAQ

What is the maximum clock/data rate supported by SN74LVC257AQDREP?

The SN74LVC257AQDREP has a maximum propagation delay of 4.6 ns at VCC = 3.3 V, supporting reliable data switching up to approximately 217 MHz in ideal conditions. Real-world achievable rate depends on load capacitance, trace length, and signal integrity margins - TI recommends limiting toggle frequency to ≤100 MHz for robust operation across the full temperature range. The SN74LVC257AQDREP does not implement internal clocking; it functions as combinational logic.

Can SN74LVC257AQDREP safely interface with 5-V microcontrollers?

Yes - the SN74LVC257AQDREP inputs are rated for voltages up to 5.5 V regardless of VCC level, allowing direct connection to 5-V GPIOs without level-shifting circuitry. Its outputs swing rail-to-rail (0 V to VCC), so interfacing with 5-V receivers requires external pull-up resistors or compatible 3.3-V-tolerant inputs. This 5.5-V tolerance is confirmed in the Absolute Maximum Ratings and Recommended Operating Conditions tables of the official datasheet.

How should the OE pin be handled during power-up to prevent bus contention?

To guarantee high-impedance outputs at power-on, OE must be held high until VCC stabilizes. TI recommends tying OE to VCC through a pull-up resistor; minimum value is determined by the driver's sink capability - typically 10 kΩ suffices for most microcontroller outputs. Leaving OE floating risks undefined output states and potential bus conflicts. This requirement applies identically to all variants including SN74LVC257AQDREP.

Is SN74LVC257AQDREP suitable for space applications?

Yes - SN74LVC257AQDREP is QML-qualified per V62/04660-01YE, meeting MIL-PRF-38535 Class V requirements for spaceflight use. It undergoes radiation hardness assurance (RHA) testing, including TID and SEE characterization, and is screened for extended temperature operation (–40°C to +125°C). Flight heritage exists in multiple LEO missions; full pedigree documentation is available from TI upon request for SN74LVC257AQDREP.

What is the difference between SN74LVC257AQDREP and SN74LVC257AQPWREP?

SN74LVC257AQDREP uses a 16-pin SOIC-D package (7.5 mm × 10.3 mm), while SN74LVC257AQPWREP uses a TSSOP-16 package (4.4 mm × 5.0 mm). Both share identical electrical specifications, QML-qualification, and top-side marking (C257AEP), but differ in thermal resistance (73°C/W vs. 108°C/W), moisture sensitivity (MSL 1 vs. MSL 1), and mechanical robustness. Layout redesign is required to substitute SN74LVC257AQDREP with SN74LVC257AQPWREP.