Nexperia USA Inc. 74AHCT257D,118

Overview

74AHCT257D,118 from Nexperia is a quad 2-input multiplexer with 3-state outputs and TTL-compatible input thresholds, operating from 4.5 V to 5.5 V supply. It features overvoltage-tolerant inputs (up to 5.5 V), Schmitt-trigger inputs for noise immunity, and supports mixed-voltage translation in bus interface applications. Its propagation delay is as low as 3.7 ns (typ.) at VCC = 5.0 V and CL = 15 pF.

For engineers reviewing the 74AHCT257D,118 datasheet, 74AHCT257D,118 pinout, 74AHCT257D,118 application, or 74AHCT257D,118 equivalent, this device serves as a logic-level-selectable data routing solution in industrial control backplanes, test equipment signal switching, and legacy TTL-to-CMOS interfacing where output enable control and high-impedance isolation are required.

Technical Context

The 74AHCT257D,118 implements four independent 2:1 multiplexers sharing a common select line (S) and a single active-low output enable (OE). Each channel routes either I0 or I1 to its Y output based on S, while OE places all outputs in high-impedance state when HIGH. The device uses standard CMOS silicon with TTL-level input recognition (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 4.5–5.5 V).

All inputs include Schmitt-trigger action for hysteresis, improving noise rejection on slow or noisy control signals. Overvoltage tolerance allows safe operation with input voltages up to 5.5 V regardless of VCC, enabling use as level translators between 3.3 V logic domains and 5 V buses without external clamping.

Key Specifications

Pinout & Package

74AHCT257D,118 is housed in a plastic small outline package (SO16), SOT109-1, with 16 leads and 3.9 mm body width. Pin 1 is marked by a notch or dot; the package is lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2-input multiplexer applications.

Compared with 74AHC257D,118 and SN74LVC257APW, the 74AHCT257D,118 uniquely bridges legacy 5 V TTL logic with modern mixed-voltage architectures - offering both input-level compatibility and overvoltage resilience absent in the LVC variant and unnecessary in pure-CMOS AHC implementations.

Availability

74AHCT257D,118 is available at Aetrix Electronics and suitable for industrial automation backplanes, automated test equipment signal routing, and legacy system interface bridging requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AHCT257D,118 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

Nexperia is a global semiconductor expert delivering high-performance, reliable logic, analog, and MOSFET solutions with emphasis on efficiency, miniaturization, and industrial-grade reliability.

The 74AHCT257D,118 belongs to Nexperia's advanced logic family designed specifically for robust signal routing in mixed-voltage industrial and instrumentation applications where TTL compatibility, noise immunity, and thermal resilience are mandatory.

FAQ

Can 74AHCT257D,118 operate with a 3.3 V supply?

No - the 74AHCT257D,118 is specified only for 4.5 V to 5.5 V operation. Its TTL-compatible input thresholds require minimum 4.5 V VCC to guarantee VIH ≥ 2.0 V and proper logic recognition. Using 3.3 V risks undervoltage lockout and undefined output states.

What is the maximum clock frequency supported for S input toggling?

The device does not specify a maximum toggle frequency for S, but propagation delay (tpd ≤ 9.0 ns max at VCC = 5.5 V, CL = 50 pF) implies reliable operation up to ~50 MHz for clean, well-sourced signals. For sustained high-frequency use, ensure input rise/fall times ≤20 ns/V and maintain proper PCB layout with ground plane and decoupling.

Is 74AHCT257D,118 pin-compatible with older 74LS257 devices?

Yes - it uses identical SO16 pinout (SOT109-1) and matches the 74LS257 function table, including active-low OE and common S control. However, it draws significantly less supply current (80 μA vs. ~20 mA) and offers improved noise immunity via Schmitt-trigger inputs.

Does OE affect propagation delay measurements?

Yes - tpd values in the datasheet assume OE = LOW (enabled state). When OE transitions from LOW to HIGH, disable time (tdis) is 9.5 ns max; when transitioning HIGH to LOW, enable time (ten) is 12.0 ns max. These delays must be included in timing budgets for bus arbitration or dynamic channel switching.