Texas Instruments SN74LS258BNS

Overview

SN74LS258BNS from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer in a 16-pin SOIC package, operating over 0°C to 70°C, with typical propagation delay of 15 ns and output drive capability of ±8 mA. It performs parallel data routing under common select and enable control, used in digital logic subsystems for bus arbitration and signal path selection.

For engineers reviewing the SN74LS258BNS datasheet, SN74LS258BNS pinout, SN74LS258BNS application, or SN74LS258BNS equivalent, key selection criteria include its TTL-compatible input thresholds, complementary enable logic (active-low G̅), quad independent channel structure, and compatibility with legacy LS-family timing and loading requirements.

Technical Context

The SN74LS258BNS implements four identical 2:1 multiplexer cells sharing a single dual-bit select input (S₀, S₁) and one active-low output enable (G̅). Each channel routes either I₀ or I₁ to Y based on select state, with outputs disabled when G̅ is high.

It uses bipolar TTL circuitry with Schottky-clamped transistors to achieve stable switching at 35 MHz maximum toggle rate, specified for V_CC = 5 V ±5%, and exhibits guaranteed noise margins of 0.4 V (low) and 0.5 V (high) across temperature.

Key Specifications

Pinout & Package

SN74LS258BNS is housed in a 16-pin small-outline integrated circuit (SOIC-16) package per TI's NS package drawing, with 1.27 mm pitch, gull-wing leads, and JEDEC-standard footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 2:1 multiplexer applications.

Compared with SN74LS257BN, SN74LS258BNS provides identical logic functionality in a space-saving SOIC package ideal for high-density layouts, while SN74LS157N adds inverted outputs at the cost of increased gate count in downstream logic - making SN74LS258BNS optimal for single-polarity bus steering.

Availability

SN74LS258BNS is available at Aetrix Electronics and suitable for computer bus arbitration, digital test equipment signal routing, legacy industrial controller I/O expansion, and EPROM programming data path control requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS258BNS 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 technologies with broad industrial and aerospace heritage.

The SN74LS258BNS belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-power digital signal routing in commercial-grade computing and instrumentation systems of the 1970s–1990s era.

FAQ

What is the primary function of the SN74LS258BNS?

The SN74LS258BNS is a quadruple 2-line to 1-line data selector/multiplexer that routes one of two input signals per channel to a common output under shared select (S₀, S₁) and enable (G̅) control. It performs deterministic, TTL-compatible digital signal path selection in bus-oriented systems, with all four channels operating synchronously using identical timing and drive characteristics. Its design enables compact implementation of parallel data switching without external gating logic.

Does the SN74LS258BNS support 3.3 V operation?

No, the SN74LS258BNS is strictly a 5 V TTL device with V_CC specification of 4.75 V to 5.25 V. It does not operate reliably at 3.3 V: input thresholds are defined for 5 V logic levels, and output drive strength degrades significantly below 4.5 V. For 3.3 V systems, designers must use level translators or select modern 3.3 V-compatible multiplexers such as the SN74LVC157A - the SN74LS258BNS remains viable only in 5 V legacy designs.

How does the SN74LS258BNS differ from the SN74LS257B?

The SN74LS258BNS and SN74LS257B are functionally identical quad 2:1 multiplexers with matching pinouts, timing, and DC specifications. The sole difference is output polarity: SN74LS258BNS provides true (non-inverted) outputs, while SN74LS257B delivers inverted outputs (Y̅). This makes SN74LS258BNS suitable for direct connection to positive-logic loads, whereas SN74LS257B requires inversion elsewhere if true outputs are needed - confirming SN74LS258BNS as the preferred choice for standard bus steering.

Is the SN74LS258BNS pin-compatible with CMOS multiplexers like the CD4052?

No, the SN74LS258BNS is not pin-compatible with the CD4052 or other CMOS multiplexers. It uses a 16-pin SOIC layout optimized for TTL-level signaling (e.g., G̅ active-low enable, S₀/S₁ binary select), while the CD4052 employs different pin assignments, dual-supply operation (V_DD/V_SS/V_EE), and analog-switch architecture. Interchange requires PCB redesign and level-shifting - the SN74LS258BNS serves strictly digital, 5 V, current-driving applications unlike the CD4052's analog/rail-to-rail switching role.

What is the maximum clock frequency supported by the SN74LS258BNS?

The SN74LS258BNS does not operate on a clock signal; it is asynchronous. Its maximum usable toggle rate is determined by propagation delay: with t_pd = 15 ns max, the device supports reliable data switching up to approximately 35 MHz in repetitive 2:1 selection patterns. This assumes clean edges, proper termination, and load capacitance ≤ 15 pF - exceeding this limit risks setup/hold violations in synchronous systems using the SN74LS258BNS as part of a larger timing chain.