Texas Instruments 74ACT11257DWR

Overview

74ACT11257DWR from Texas Instruments is a quadruple 2-line-to-1-line data selector/multiplexer with 3-state outputs, designed for bus-organized systems. It features TTL-voltage-compatible inputs, ±24 mA output drive at 5 V, 4.4 ns typical propagation delay (A/B to Y), and operates across −40°C to 85°C. It enables signal routing from four dual-source data buses to four independent output lines in high-speed digital backplanes.

For engineers reviewing the 74ACT11257DWR datasheet, 74ACT11257DWR pinout, 74ACT11257DWR application, or 74ACT11257DWR equivalent, this device supports critical timing-sensitive bus interface design, latch-up-immune operation (500 mA typical at 125°C), and flow-through PCB layout optimization via center-pin V_CC/GND configuration.

Technical Context

The 74ACT11257DWR implements four independent 2:1 multiplexers sharing a common output-enable (OE) control and select (A/B) line. Each channel selects between two inputs (A or B) and drives a dedicated 3-state output (Y), with all outputs disabled when OE is high. Its EPIC (Enhanced-Performance Implanted CMOS) 1-μm process ensures rail-to-rail output swing and low dynamic power dissipation.

Logic-level compatibility is maintained through TTL-input thresholds (V_IL ≤ 0.8 V, V_VIH ≥ 2 V) and CMOS-output drive strength. The device supports hot-swap-capable bus interfacing via fast enable/disable timing (t_PZH/t_PHZ ≤ 8.4 ns max), and its center-aligned V_CC/GND pins minimize simultaneous switching noise in dense layouts.

Key Specifications

Pinout & Package

74ACT11257DWR uses a 20-pin SOIC (DW) package with 3.90 mm body width, 2.65 mm max height, and 1.27 mm lead pitch. Pin 1 is marked by a beveled corner; V_CC (pins 15, 16) and GND (pins 4, 5, 6, 7) are centrally located to reduce ground bounce and supply noise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multiplexer applications.

Compared with 74ACT11257DWR, the 74ACT157DWR offers identical functionality with reduced noise suppression and latch-up margin, while SN74LVC157DR shifts voltage domain and timing performance - making the 74ACT11257DWR optimal for legacy 5-V industrial bus interfaces demanding robustness and layout efficiency.

Availability

74ACT11257DWR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automated test equipment, legacy bus interface modules, and high-reliability data acquisition systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74ACT11257DWR 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 logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.

The 74ACT family delivers advanced CMOS logic with TTL compatibility, optimized for high-speed, noise-immune digital systems - specifically targeting industrial control, instrumentation, and legacy infrastructure upgrades.

FAQ

What is the maximum operating frequency supported by the 74ACT11257DWR?

The 74ACT11257DWR does not specify a maximum clock frequency in its datasheet, but its 6.9 ns maximum propagation delay (A/B to Y at 25°C) supports reliable operation up to approximately 145 MHz in ideal conditions. Real-world bus timing must account for load capacitance, trace inductance, and setup/hold margins - typically limiting practical use to ≤80 MHz in 50-pF loaded systems. The 74ACT11257DWR's t_PZH/t_PHZ values confirm fast bus turnaround suitable for burst-mode transfers.

Does the 74ACT11257DWR require external pull-up resistors on its 3-state outputs?

No, the 74ACT11257DWR does not require external pull-up resistors on its 3-state outputs. Its outputs are actively driven to valid logic levels (V_OH ≥ 4.94 V, V_OL ≤ 0.44 V at V_CC = 5.5 V) when enabled, and present high-impedance (I_OZ ≤ ±5 μA) when disabled. Pull-ups are unnecessary unless the system design mandates weak biasing during high-Z states - a scenario not addressed in the 74ACT11257DWR's specification or application guidance.

Can the 74ACT11257DWR operate reliably at 4.5 V supply voltage?

Yes, the 74ACT11257DWR is fully characterized for operation at 4.5 V V_CC, with guaranteed parameters including VOH ≥ 3.94 V, VOL ≤ 0.44 V, and t_PLH/t_PHL ≤ 6.9 ns across −40°C to 85°C. Its recommended operating range explicitly spans 4.5 V to 5.5 V, and electrical characteristics tables include 4.5 V test conditions - confirming robust functionality at the lower rail, essential for brown-out tolerant industrial systems using the 74ACT11257DWR.

How does the center-pin V_CC/GND configuration of the 74ACT11257DWR improve noise performance?

The center-pin V_CC (pins 15, 16) and GND (pins 4–7) placement in the 74ACT11257DWR reduces high-frequency switching noise by minimizing power/ground loop inductance. This geometry shortens current return paths for all 20 pins, lowering Δi/Δt-induced voltage spikes. TI's datasheet confirms this layout "minimizes high-speed switching noise" - a measurable benefit validated by 500 mA latch-up immunity and clean eye diagrams in backplane applications using the 74ACT11257DWR.

Is the 74ACT11257DWR pin-compatible with the 74ACT157DWR?

Yes, the 74ACT11257DWR is pin-compatible with the 74ACT157DWR in the DW package: both share identical 20-pin SOIC footprints, pin numbering, and functional assignments (including A/B, OE, 1A–4B, 1Y–4Y). However, the 74ACT11257DWR adds center-placed V_CC/GND pins (pins 15/16 and 4–7) versus the 74ACT157DWR's corner-placed power pins - meaning PCB layout must accommodate the enhanced grounding scheme to realize full noise immunity benefits of the 74ACT11257DWR.