Texas Instruments SN74HC158D

Overview

SN74HC158D from Texas Instruments is a high-speed CMOS 4-bit 2-to-1 data selector/multiplexer with active-low enable (G), inverting outputs, and dual-data-source selection capability. It operates from 2 V to 6 V, delivers 11 ns typical propagation delay at 6 V, supports ±6-mA output drive, and drives up to 15 LSTTL loads - used in digital logic routing, bus arbitration, and address/data path switching in industrial control systems.

For engineers reviewing the SN74HC158D datasheet, SN74HC158D pinout, SN74HC158D application, or SN74HC158D equivalent, key selection considerations include its inverted-output behavior, strobe-controlled gating, guaranteed operation across 2–6 V supply, low 80-µA max ICC, and SOIC-16 package compatibility with legacy 74LS/74HC board layouts.

Technical Context

The SN74HC158D implements four independent 2:1 multiplexer channels sharing a common active-low strobe (G) input and a single select line (A/B). Each channel selects between two complementary inputs (e.g., 1A/1B) and routes the chosen signal - inverted - to its corresponding output (1Y, 2Y, etc.). All logic functions conform to standard positive-logic truth table behavior with inversion applied at output stage.

Its architecture requires all unused inputs to be tied to VCC or GND per TI SCBA004 guidance; no internal pull-ups/pull-downs are provided. The device uses silicon-gate CMOS technology, ensuring TTL-compatible input thresholds (VIH = 3.15 V min at VCC = 4.5 V) and rail-to-rail output swing under load.

Key Specifications

Pinout & Package

SN74HC158D is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package, 7.5 mm wide, with 1.27 mm pitch, JEDEC MS-012 compliant, RoHS-compliant NiPdAu lead finish, and moisture sensitivity level (MSL) 1 (unlimited floor life at ≤30°C/60% RH).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC158D, SN74HC157D offers identical timing and drive but lacks output inversion - requiring logic-level adjustments in downstream stages. 74ACT158SOIC trades wider voltage support and lower power for higher speed and 5 V-only operation, limiting flexibility in modern low-voltage embedded systems.

Availability

SN74HC158D is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, digital test equipment signal routing, and legacy bus interface adapter designs requiring stable component supply, long-term lifecycle assurance, and drop-in compatibility with existing SOIC-16 footprints.

Supply support for SN74HC158D 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, automotive, and communications market reach.

The SN74HC158D belongs to TI's 74HC high-speed CMOS logic family, designed specifically to replace obsolete 74LS devices with lower power, wider voltage tolerance, and improved noise immunity in industrial control and instrumentation applications.

FAQ

What logic function does the SN74HC158D implement?

The SN74HC158D implements a 4-bit 2-to-1 data selector/multiplexer with active-low strobe (G) and inverting outputs. For each of four channels, it selects either input A or B based on the A/B control line, passes the selected input through an inverter, and presents the result at the corresponding Y output. When G is HIGH, all outputs are forced HIGH regardless of A/B or data states.

Can SN74HC158D operate at 3.3 V supply?

Yes, SN74HC158D is fully specified for operation from 2 V to 6 V, including 3.3 V nominal supplies. At VCC = 3.3 V, it maintains valid VIH (≥2.31 V) and VIL (≤1.09 V) thresholds, delivers ≥±4 mA output drive, and achieves ~15 ns typical propagation delay (CL = 50 pF), making it suitable for mixed-voltage 3.3 V/5 V system interfaces.

Is SN74HC158D pin-compatible with SN74HC157D?

Yes, SN74HC158D and SN74HC157D share identical SOIC-16 pinouts, supply ranges, timing, and drive specifications - differing only in output polarity (inverting vs. non-inverting). This allows direct PCB replacement when system-level logic accommodates the polarity change, or when an external inverter is acceptable.

What is the maximum capacitive load SN74HC158D can drive reliably?

SN74HC158D is characterized up to CL = 150 pF in datasheet switching tables. At 6 V supply, tpd increases from 11 ns (50 pF) to 45 ns (150 pF), and output transition time (tt) rises from 13 ns to 45 ns. For reliable operation beyond 150 pF, add a buffer stage or reduce trace length/capacitance - the device itself does not specify derating beyond this limit.

Does SN74HC158D require external pull-up or pull-down resistors on unused inputs?

Yes - per TI application report SCBA004, all unused inputs of SN74HC158D must be tied to VCC or GND. Floating CMOS inputs cause increased ICC, potential oscillation, and ESD susceptibility. No internal termination is provided; 10 kΩ pull-up/down resistors are recommended for unconnected A/B, G, or data inputs.