Texas Instruments SN74HC258DT

Overview

SN74HC258DT from Texas Instruments is a quadruple 2-line to 1-line inverting data selector/multiplexer with 3-state outputs, operating across 2 V to 6 V supply voltage. It features 12 ns typical propagation delay at 5 V, ±6 mA output drive capability, and high-impedance outputs controlled by an active-low strobe (G) input. It is used in bus interface applications where multiple data sources must be selectively routed to shared data lines in digital systems.

For engineers reviewing the SN74HC258DT datasheet, SN74HC258DT pinout, SN74HC258DT application, or SN74HC258DT equivalent, key selection criteria include its inverted output logic, 3-state enable timing (13 ns enable time at 6 V), compatibility with LSTTL loads, and SOIC-16 package footprint for space-constrained PCB layouts.

Technical Context

The SN74HC258DT implements four independent 2:1 multiplexers sharing common address (A/B) and active-low strobe (G) inputs. Each channel selects between two inputs (A or B) and passes the inverted value to its Y output when G is low; all outputs enter high-impedance state when G is high.

Its CMOS HC-family design ensures low static current (≤80 µA ICC max), rail-to-rail output swing, and compatibility with both TTL and CMOS logic families. Input thresholds are specified relative to VCC (VIH = 3.15 V min at 4.5 V), supporting robust noise margins in mixed-voltage systems.

Key Specifications

Pinout & Package

SN74HC258DT uses a 16-pin SOIC (D) package with nominal body size 9.90 mm × 3.90 mm and standard 1.27 mm pitch. Pin numbering follows JEDEC MS-012, with Pin 1 in top-left corner marked by index notch or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC257DR and 74LVC257PW, SN74HC258DT provides unique inverted-output behavior in a widely available SOIC-16 package, making it optimal for legacy bus architectures requiring polarity inversion without additional gate logic.

Availability

SN74HC258DT is available at Aetrix Electronics and suitable for industrial control bus multiplexing, legacy system signal routing, test equipment channel selection, and digital audio data switching requiring stable component supply and long-term obsolescence management.

Supply support for SN74HC258DT 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 company specializing in analog, embedded processing, and logic ICs, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74HC258DT belongs to TI's industry-standard 74HC logic family, designed for robust, low-power digital signal routing in mixed-voltage systems where reliability and interoperability across legacy and modern logic families are essential.

FAQ

What is the function of the G (strobe) input on the SN74HC258DT?

The G input on the SN74HC258DT is an active-low 3-state enable control. When G is low, the selected outputs (Y1–Y4) drive inverted logic values based on A/B and input data; when G is high, all outputs enter high-impedance state regardless of A/B or input states. This allows safe bus sharing and prevents signal contention during data transitions. The SN74HC258DT datasheet specifies 13 ns typical enable time at 6 V.

Does the SN74HC258DT support 3.3 V operation?

Yes, the SN74HC258DT fully supports 3.3 V operation within its 2 V to 6 V supply range. At VCC = 3.3 V, it delivers guaranteed VOH ≥ 2.97 V and VOL ≤ 0.33 V under 6 mA load, meeting standard 3.3 V LVTTL thresholds. Its input thresholds scale proportionally (VIH ≥ 2.31 V), ensuring reliable interfacing with 3.3 V microcontrollers and FPGAs without level translation. The SN74HC258DT maintains 12 ns typical propagation delay at 5 V but increases to ~18 ns at 3.3 V per TI characterization data.

How does the SN74HC258DT differ from the SN74HC257 series?

The SN74HC258DT differs from the SN74HC257 series solely in output polarity: SN74HC258DT provides inverted outputs (Y = NOT(selected input)), while SN74HC257 provides non-inverted outputs (Y = selected input). All other parameters-including pinout, timing (12 ns vs. 9 ns tpd), supply range, 3-state behavior, and package options-are functionally identical. The SN74HC258DT is not a drop-in replacement for SN74HC257 in circuits relying on true-level outputs, as signal inversion would break logic functionality unless compensated elsewhere.

What is the maximum capacitive load the SN74HC258DT can drive reliably?

The SN74HC258DT is characterized for CL = 50 pF and CL = 150 pF in its switching specifications. At 5 V supply, it maintains 12 ns typical tpd up to 50 pF; at 150 pF, tpd increases to 25 ns (typical). TI recommends limiting total load (including trace capacitance and connected inputs) to ≤150 pF for predictable timing. Exceeding this may cause marginal setup/hold violations or increased transition times. The SN74HC258DT output structure supports ±6 mA drive, which corresponds to ~15 LSTTL loads - consistent with its rated fanout capability.

Is the SN74HC258DT RoHS compliant?

No, the SN74HC258DT is marked as Obsolete in TI's packaging addendum and carries no RoHS compliance designation. Its material status indicates "Call TI" for lead finish and MSL rating, and historical documentation confirms use of SnPb (tin-lead) terminations. For RoHS-compliant alternatives, consider active variants like SN74HC258DR (SOIC-16, NIPDAU finish, Level-1 MSL rating) or SN74HC258PWR (TSSOP-16, RoHS-compliant). The SN74HC258DT remains suitable for legacy repair or military/aerospace applications where SnPb is permitted.