Texas Instruments SN74AS250ADW

Overview

SN74AS250ADW from Texas Instruments is a 4-line-to-1-line 16-channel TTL multiplexer with inverting W output, 3-state bus driver inputs, symmetrical propagation delay (2–8 ns), and operation over 0°C to 70°C. It selects one of 16 data inputs (E0–E15) using address lines A–D and enables/disables output via buffered OE, used in parallel-to-serial conversion and Boolean function generation.

For engineers reviewing the SN74AS250ADW datasheet, SN74AS250ADW pinout, SN74AS250ADW application, or SN74AS250ADW equivalent, this device supports high-speed digital logic selection in legacy industrial control, test equipment, and data routing systems where TTL-level compatibility, low-output skew, and 3-state bus isolation are required.

Technical Context

The SN74AS250ADW implements full binary decoding across four select inputs (A–D) to route one of sixteen data sources (E0–E15) to an inverting W output. Its internal logic ensures symmetrical tPLH/tPHL timing, minimizing transient risk during switching transitions.

It features a buffered 3-state output-enable (OE) input that places W in high-impedance without affecting internal data latching - enabling cascaded n-line-to-1-line multiplexing while allowing new input setup during output disable.

Key Specifications

Pinout & Package

SN74AS250ADW uses a 24-pin plastic small-outline (DW) package with 300-mil width, gull-wing leads, and JEDEC MO-153AA compliance. Pin 1 is marked by notch or dot; pin numbering follows standard dual-inline convention.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-channel TTL multiplexer applications.

Compared with SN74AS250ADW, SN74AS850N omits scalability and bus isolation, while SN74F250N trades power efficiency for marginal speed gain - making SN74AS250ADW optimal for balanced performance in commercial instrumentation and control systems.

Availability

SN74AS250ADW is available at Aetrix Electronics and suitable for industrial control systems, legacy test equipment upgrades, and data acquisition modules requiring stable component supply and long-term obsolescence management.

Supply support for SN74AS250ADW 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74AS250ADW belongs to TI's Advanced Schottky TTL logic family, designed for high-speed, low-skew digital routing in commercial-grade systems where reliability and interoperability with legacy 5 V logic are essential.

FAQ

What logic family does SN74AS250ADW belong to, and how does it interface with modern microcontrollers?

SN74AS250ADW is an Advanced Schottky TTL device with VIH ≥ 2.0 V and VIL ≤ 0.8 V, making it directly compatible with 5 V-tolerant GPIOs of legacy microcontrollers (e.g., 8051, PIC16F) and FPGA I/O banks configured for LVTTL. Its 48 mA sink capability allows direct connection without level-shifting, though newer 3.3 V-only MCUs require translation circuitry. SN74AS250ADW maintains robust noise margins in electrically noisy environments typical of industrial control panels.

Does SN74AS250ADW support cascading for more than 16 inputs, and how is it implemented?

Yes, SN74AS250ADW supports n-line-to-1-line cascading using its buffered OE input. Multiple devices can share common A–D address lines, with each unit enabled via unique OE control (e.g., decoded from higher-order address bits). The W outputs feed a second-stage multiplexer or wired-OR bus. SN74AS250ADW's OE independence from internal latching permits seamless handoff between stages without data corruption during transition.

What is the significance of the inverting W output in SN74AS250ADW, and when is it advantageous?

The inverting W output of SN74AS250ADW delivers the logical complement of the selected Ei input, eliminating the need for external inverters in sum-of-products logic synthesis (e.g., PLA implementations). This feature reduces component count and propagation delay in Boolean function generators, and simplifies active-low signal routing in bus arbitration or enable schemes. SN74AS250ADW retains full 3-state control regardless of inversion polarity.

How does SN74AS250ADW handle simultaneous address and data changes, and what timing guarantees apply?

SN74AS250ADW guarantees symmetrical tPLH/tPHL (2–8 ns) and specifies setup/hold times relative to address transitions. Its internal decoding ensures glitch-free output transitions when A–D change synchronously with stable Ei inputs. The datasheet confirms no minimum pulse width requirement on address lines, and SN74AS250ADW tolerates overlapping changes provided OE remains active - critical for real-time data routing in oscilloscope trigger logic or protocol analyzers.

Is SN74AS250ADW RoHS compliant, and what packaging details apply to the DW variant?

SN74AS250ADW is not RoHS compliant - it uses leaded solder finish per legacy AS-series manufacturing. The DW package is a 24-pin plastic small-outline (SOIC) with 300-mil body width, gull-wing leads, and JEDEC MO-153AA mechanical dimensions. Pin 1 location is marked by notch or dot; thermal pad is absent. TI discontinued new RoHS-compliant variants, so SN74AS250ADW remains available through authorized distributors for legacy repair and continuity programs.