Texas Instruments SN74ALS258ANG4

Overview

SN74ALS258ANG4 from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer with 3-state outputs, designed for bus-organized systems. It selects one of two 4-bit data sources (A or B) per channel under A/B control, enables/disables all outputs via OE, and operates at 0°C to 70°C with 5 V supply. It interfaces directly with system buses in high-performance digital logic applications.

For engineers reviewing the SN74ALS258ANG4 datasheet, SN74ALS258ANG4 pinout, SN74ALS258ANG4 application, or SN74ALS258ANG4 equivalent, key selection criteria include its 3-state bus interface capability, propagation delay (tPLH/tPHL ≤ 8 ns), output drive strength (IOL = 24 mA), and compatibility with standard TTL logic families in legacy industrial control and instrumentation designs.

Technical Context

The SN74ALS258ANG4 implements four independent 2:1 multiplexers sharing a common A/B select line and output-enable (OE) input. Each channel routes either the A or B input to its Y output based on the logic level of A/B, while OE controls high-impedance state across all four outputs simultaneously.

It belongs to the ALS (Advanced Low-Power Schottky) logic family, offering lower power consumption than standard LS TTL while maintaining compatible voltage thresholds (VIH = 2 V, VIL = 0.8 V) and higher noise immunity. Its 3-state outputs prevent bus contention during multi-source data routing in shared-data-path architectures.

Key Specifications

Pinout & Package

SN74ALS258ANG4 is supplied in a 16-pin plastic dual in-line package (PDIP-N), 300-mil width, with through-hole mounting and industry-standard pin spacing (0.1 inch).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALS257AN and SN74AS258N, SN74ALS258ANG4 uniquely balances low power (13 mA max ICC), robust 24 mA drive, and unified A/B control - making it optimal for cost-sensitive, thermally constrained, and bus-synchronized legacy digital systems requiring reliable 4-bit multiplexing.

Availability

SN74ALS258ANG4 is available at Aetrix Electronics and suitable for industrial PLCs, legacy test equipment, computer backplane expansion, and digital audio control systems requiring stable component supply and long-term obsolescence management.

Supply support for SN74ALS258ANG4 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 SN74ALS258ANG4 belongs to TI's legacy 74ALS logic family, engineered for high-reliability, low-power, TTL-compatible digital interfacing in mission-critical industrial and instrumentation applications.

FAQ

What is the function of the A/B pin on the SN74ALS258ANG4?

The A/B pin is a common select input that determines which of the two 4-bit data sources (A-side or B-side) is routed to the four Y outputs. When A/B is low, inputs 1A–4A pass to outputs 1Y–4Y; when high, inputs 1B–4B pass. This unified control simplifies synchronization across all channels in bus-oriented systems, and is a defining feature distinguishing SN74ALS258ANG4 from variants like SN74ALS257AN.

Does SN74ALS258ANG4 support 3.3 V operation?

No, SN74ALS258ANG4 is specified only for 4.5 V to 5.5 V supply operation and is not 3.3 V tolerant. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V) are optimized for 5 V TTL systems. Applying 3.3 V to VCC may result in undefined logic states or failure to meet timing specifications, and is outside the device's recommended operating conditions.

How does the OE pin affect output behavior in SN74ALS258ANG4?

The OE (Output Enable) pin is active-low and globally controls all four Y outputs. When OE is high, all outputs enter high-impedance (3-state) mode, electrically disconnecting them from the bus. When OE is low, outputs actively drive logic levels based on A/B and input data. This enables safe bus sharing among multiple devices, and the SN74ALS258ANG4's tPZH/tPHZ ≤ 18 ns ensures rapid, glitch-free bus release during arbitration.

Can SN74ALS258ANG4 replace SN74LS258 in existing designs?

Yes, SN74ALS258ANG4 is a direct functional and pin-compatible upgrade to SN74LS258, offering identical pinout, logic function, and voltage thresholds, but with lower power consumption (ICC ≤ 13 mA vs. ~20 mA for LS) and improved noise immunity. No PCB changes are required, and the enhanced speed (8 ns vs. 15 ns typical) provides additional timing margin in legacy 5 V systems.

What is the maximum capacitive load SN74ALS258ANG4 can drive reliably?

SN74ALS258ANG4 is characterized for CL = 50 pF in switching tests, and its 24 mA low-level output current supports driving typical PCB traces plus up to 10 standard LS-TTL inputs (each ~20 pF). For heavier loads (>100 pF), series termination or buffer stages are recommended to maintain signal integrity and meet tPLH/tPHL ≤ 8 ns timing guarantees across temperature and voltage extremes.