Texas Instruments SN74F258N

Overview

SN74F258N from Texas Instruments is a quadruple 2-line-to-1-line data selector/multiplexer with 3-state outputs, designed for bus-organized digital systems. It features four independent 2:1 multiplexers, 3-state output control via OE pin, operates at 4.5–5.5 V supply, and supports 0°C to 70°C industrial temperature range. It enables selective routing of dual-source 4-bit data onto shared system buses.

For engineers reviewing the SN74F258N datasheet, SN74F258N pinout, SN74F258N application, or SN74F258N equivalent, key selection considerations include its 16-pin PDIP package, 3-state bus interface capability, propagation delay (≤6 ns), output drive strength (24 mA sink), and compatibility with TTL-level logic families in legacy computing and industrial control designs.

Technical Context

The SN74F258N implements four independent 2:1 multiplexers, each selecting between two input lines (A or B) based on the A/B select line. All outputs are controlled by a common active-low Output Enable (OE) signal, placing them in high-impedance state when asserted.

It uses standard TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_VIH ≥ 2.0 V) and delivers rail-to-rail 3-state outputs with guaranteed VOL ≤ 0.5 V at 24 mA sink and VOH ≥ 2.4 V at −3 mA source, ensuring robust noise margins in mixed-signal backplane environments.

Key Specifications

Pinout & Package

SN74F258N is supplied in a 16-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and through-hole mounting. Pin spacing conforms to JEDEC MS-001 standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F258N, SN74LS258N trades speed and drive for reduced power, while SN74HC258N shifts to CMOS characteristics-neither offers pin-compatible drop-in replacement without verifying voltage thresholds, timing budgets, and bus loading requirements.

Availability

SN74F258N is available at Aetrix Electronics and suitable for computer backplane design, industrial PLC development, and legacy test equipment repair requiring stable component supply and long-term obsolescence management.

Supply support for SN74F258N 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and automotive qualification.

The SN74F258N belongs to TI's 74F family of fast TTL logic devices, engineered for high-speed digital systems requiring reliable bus interfacing and deterministic timing in commercial temperature environments.

FAQ

What is the function of the A/B pin on the SN74F258N?

The A/B pin is a common select input that determines which of the two data inputs (A or B) is routed to each of the four outputs (1Y–4Y) in the SN74F258N. When A/B is low, all Y outputs reflect their corresponding A inputs; when high, they reflect their B inputs. This enables synchronized 4-bit data path selection without individual channel controls.

Does the SN74F258N support hot-swapping on a live bus?

The SN74F258N supports controlled bus disconnection via its active-low OE pin, but it is not hot-swap rated. Its absolute maximum ratings allow −0.5 V to 5.5 V on disabled outputs, permitting safe insertion only if bus voltages are stabilized and no dynamic transients exceed those limits. Full hot-swap compliance requires additional protection circuitry beyond the SN74F258N itself.

Can the SN74F258N operate from a 3.3 V supply?

No, the SN74F258N requires a minimum supply voltage of 4.5 V per its recommended operating conditions. At 3.3 V, it fails to meet TTL input threshold specifications (VIH ≥ 2.0 V becomes marginal) and cannot guarantee VOH or VOL performance. Use SN74HC258N instead for true 3.3 V operation.

What is the purpose of the NC pins on the SN74F258N PDIP package?

The SN74F258N PDIP package has no NC (No Connection) pins - all 16 pins are assigned functional roles per the datasheet pinout. Confusion may arise from other packages (e.g., FK ceramic chip carrier), but the N-package pin map shows continuous numbering with no unconnected terminals. Each pin serves a defined signal or power function.

How does the SN74F258N differ from the SN74F157 in functionality?

The SN74F258N integrates a common A/B select line across all four 2:1 multiplexers, whereas the SN74F157 uses individual select lines per channel. This makes SN74F258N ideal for parallel data path selection (e.g., choosing between two 4-bit buses), while SN74F157 supports independent channel control - a distinction critical for bus arbitration versus per-signal routing architectures.