Texas Instruments CD74ACT257EE4

Overview

CD74ACT257EE4 from Texas Instruments is a quad 2-input CMOS multiplexer with three-state non-inverting outputs, designed for data routing in digital logic systems. It features 12 ns typical propagation delay at 5 V/15 pF, -55°C to 125°C operating temperature range, and active-low output enable (OE) for bus isolation. It is commonly used in register-to-bus data selection and function generation circuits.

For engineers reviewing the CD74ACT257EE4 datasheet, CD74ACT257EE4 pinout, CD74ACT257EE4 application, or CD74ACT257EE4 equivalent, key selection criteria include its 16-pin PDIP package, HCT-compatible input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V), three-state output drive capability, and guaranteed operation across extended industrial and military temperature ranges.

Technical Context

The CD74ACT257EE4 implements four independent 2:1 multiplexers sharing a common select (S) and output enable (OE) control. Each channel routes one of two data inputs (I0/I1) to its respective three-state output (Y) based on S state, with OE asserting high-impedance when logic high.

It uses advanced CMOS technology optimized for TTL-level compatibility: input thresholds match LSTTL (VIH = 2 V min, VIL = 0.8 V max at VCC = 5 V), while output drive meets ±24 mA sink/source capability under load, enabling direct interface with legacy TTL buses without level-shifting.

Key Specifications

Pinout & Package

CD74ACT257EE4 is supplied in a 16-lead plastic dual in-line package (PDIP), with 0.3-inch body width and through-hole mounting. Pin 1 is located at the top-left corner adjacent to the notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74ACT257EE4, SN74ACT257N offers identical timing and drive strength with updated manufacturing traceability, while CD74HCT257E trades 1 ns of speed for broader process tolerance and lower dynamic power-making it suitable for less timing-critical 5 V control logic.

Availability

CD74ACT257EE4 is available at Aetrix Electronics and suitable for aerospace avionics, industrial programmable logic controllers, and military embedded computing systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74ACT257EE4 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The CD74ACT series targets high-speed, TTL-compatible CMOS logic applications demanding precise timing, wide temperature operation, and robust noise immunity in mission-critical systems.

FAQ

What logic family does CD74ACT257EE4 belong to, and how does it differ from HC or HCT variants?

CD74ACT257EE4 belongs to the Advanced CMOS Technology (ACT) logic family. Unlike HC (2–6 V operation) or HCT (4.5–5.5 V with TTL-compatible inputs), ACT devices combine HCT's input thresholds with improved speed and drive strength: 12 ns typical propagation delay and ±24 mA output current at 5 V. This makes CD74ACT257EE4 optimal for high-fanout, noise-immune 5 V systems where HC lacks drive and HCT lacks speed.

Does CD74ACT257EE4 support operation outside the standard 5 V supply range?

No. CD74ACT257EE4 is specified only for 4.5 V to 5.5 V operation. Its input thresholds, propagation delays, and output drive characteristics are characterized and guaranteed exclusively within this range. Operation below 4.5 V may result in undefined logic states or excessive delay; above 5.5 V risks exceeding absolute maximum ratings and causing permanent damage.

Can CD74ACT257EE4 be used in place of CD74HC257E in an existing design?

CD74ACT257EE4 can replace CD74HC257E only if the design operates strictly at 5 V with adequate noise margin and timing budget. While both share pinout and basic functionality, CD74ACT257EE4 draws higher supply current under switching loads and delivers stronger output drive (±24 mA vs. ±4 mA). Verify PCB decoupling, thermal dissipation, and downstream loading to prevent signal integrity issues or overstress.

What is the maximum capacitive load CD74ACT257EE4 can drive while maintaining specified timing?

CD74ACT257EE4 is characterized for CL = 15 pF (12 ns typical delay) and CL = 50 pF (up to 45 ns max delay at -55°C to +125°C). Driving loads beyond 50 pF will increase propagation delay nonlinearly and may violate setup/hold timing in synchronous systems. For >50 pF loads, add a buffer stage or reduce trace length and parallel stubs to maintain signal fidelity.

Is CD74ACT257EE4 suitable for use in high-reliability aerospace applications?

Yes. CD74ACT257EE4 is offered in a military-qualified version (CD54ACT257) meeting MIL-PRF-38535 Class K standards, and the commercial CD74ACT257EE4 shares the same die and process. Its -55°C to +125°C rating, 150°C max junction temperature, and electrostatic discharge protection make it appropriate for avionics, satellite subsystems, and ground-based radar control units when qualified per program-specific reliability testing.