Texas Instruments SN74ALS151DRE4

Overview

SN74ALS151DRE4 from Texas Instruments is an 8-line to 1-line TTL-compatible data selector/multiplexer with active-low enable (G), three binary select inputs (A, B, C), eight data inputs (D0–D7), and complementary outputs (Y and W). It operates from 4.5 V to 5.5 V at 0°C to 70°C, delivers 24 mA low-level output drive, and achieves 10 ns typical propagation delay from data input to Y output. It serves as a Boolean function generator in digital logic control subsystems.

For engineers reviewing the SN74ALS151DRE4 datasheet, SN74ALS151DRE4 pinout, SN74ALS151DRE4 application, or SN74ALS151DRE4 equivalent, key selection criteria include its 16-pin SOIC (D) package, dual active-high/active-low outputs (Y/W), guaranteed 24 mA sink capability, and compatibility with legacy ALS logic families in industrial control and instrumentation signal routing.

Technical Context

The SN74ALS151DRE4 implements full binary decoding of A/B/C inputs to route exactly one of eight data inputs to the Y output when strobe (G) is low; W provides the logical complement of Y. Its internal architecture uses bipolar ALS (Advanced Low-Power Schottky) transistor technology, enabling higher speed and lower power than standard LS logic while maintaining TTL voltage thresholds.

Input clamping diodes are integrated on all data and select inputs, simplifying system-level ESD protection and reducing external component count. The device features totem-pole outputs - not open-collector - and does not support 3-state operation; both Y and W are always driven high or low based on selection and enable state.

Key Specifications

Pinout & Package

SN74ALS151DRE4 is housed in a 16-pin plastic small-outline integrated circuit (SOIC) package per JEDEC MS-012, 7.5 mm body width, 1.75 mm max height, with 1.27 mm lead pitch. Pin 1 is marked by a beveled corner or notch on the package top edge.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-line to 1-line multiplexer applications.

Compared with SN74ALS151DRE4, SN74ALS151N offers identical logic behavior in through-hole form for serviceability, while SN74AS151NSR trades higher power for 30% faster switching - critical in high-frequency data acquisition but unnecessary in stable control loops.

Availability

SN74ALS151DRE4 is available at Aetrix Electronics and suitable for industrial control panels, digital instrumentation, and legacy system repair requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74ALS151DRE4 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 SN74ALS151DRE4 belongs to TI's legacy Advanced Low-Power Schottky (ALS) logic family, engineered for reliable 5 V digital signal routing in cost-sensitive, thermally constrained commercial systems where speed-power balance matters.

FAQ

What is the maximum operating frequency supported by SN74ALS151DRE4?

The SN74ALS151DRE4 does not specify a maximum clock frequency, but its worst-case propagation delay from data input to Y output is 15 ns (tPHL, D→Y). This supports reliable operation in synchronous systems with clock periods ≥30 ns (i.e., ≤33 MHz), assuming setup/hold times are met. The SN74ALS151DRE4 is not a clocked sequential device - it is combinatorial - so timing depends solely on input transition stability relative to enable and select signals.

Does SN74ALS151DRE4 support 3-state (high-impedance) outputs?

No, the SN74ALS151DRE4 does not feature 3-state outputs. It has two active-drive outputs: Y (true) and W (complement), both of which are continuously driven high or low depending on input states and strobe (G) level. When G is high, Y is forced low and W is forced high - neither enters high-impedance mode. For bus-sharing applications requiring tri-state capability, consider alternatives like SN74LS251 or SN74ALS251.

Can SN74ALS151DRE4 be used with 3.3 V logic systems?

The SN74ALS151DRE4 is designed for 5 V TTL operation and requires VCC = 4.5 V to 5.5 V. Its input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) are incompatible with 3.3 V logic levels: a 3.3 V high signal may not reliably exceed VIH, and noise margins shrink significantly. Direct interfacing risks metastability or incorrect selection. Use level-shifting buffers (e.g., SN74LVC245) if integrating SN74ALS151DRE4 into mixed-voltage systems.

What is the purpose of the W output on SN74ALS151DRE4?

The W output on SN74ALS151DRE4 is the logical complement of the Y output - when Y is high, W is low, and vice versa - under all valid operating conditions (G = L). This eliminates the need for an external inverter in applications requiring both true and inverted versions of the selected data, such as differential signaling paths, dual-edge-triggered logic, or redundant fault-detection circuits. W is not a separate function; it mirrors Y with identical timing and drive strength.

Is SN74ALS151DRE4 RoHS compliant?

Yes, SN74ALS151DRE4 is RoHS compliant. Per Texas Instruments' packaging documentation, the part uses NiPdAu (nickel-palladium-gold) lead finish and meets EU Directive 2011/65/EU requirements. It carries MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH) and is supplied in tape-and-reel format (2500 units per reel), confirming full compliance for modern SMT manufacturing environments.