Texas Instruments SN74AHC158N

Overview

SN74AHC158N from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC operating from 2 V to 5.5 V, featuring a common strobe (G) input, inverted outputs, and 16-pin PDIP packaging. It routes one of two 4-bit input sources to four inverted outputs based on the A/B select line, with propagation delays as low as 4.1 ns at 5 V and ±8 mA output drive capability.

For engineers reviewing the SN74AHC158N datasheet, SN74AHC158N pinout, SN74AHC158N application, or SN74AHC158N equivalent, this device serves as a logic-level data routing solution in bus management, address decoding, and signal selection circuits where low-power CMOS compatibility, wide supply range, and deterministic enable-controlled output states are required.

Technical Context

The SN74AHC158N implements four independent 2:1 multiplexers sharing a single active-low strobe (G) and a common select input (A/B). When G is high, all Y outputs are forced high regardless of inputs; when G is low, each Yn selects between An and Bn per the A/B state and drives inverted logic.

Its AHC logic family ensures TTL-compatible input thresholds, rail-to-rail output swing, and ESD protection exceeding 2000-V HBM. The device supports mixed-voltage interfacing across 2–5.5 V operation and exhibits latch-up immunity >250 mA per JESD 17.

Key Specifications

Pinout & Package

SN74AHC158N uses a 16-pin plastic dual in-line package (PDIP-N) with 0.3-inch body width and through-hole mounting. Pin 1 is located at the top-left corner adjacent to the notch or dot marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV158N and 74HC158N, the SN74AHC158N delivers optimal balance of speed (4.1 ns), drive strength (±8 mA), and supply flexibility (2–5.5 V), making it preferred for new designs requiring fast, robust, mixed-voltage data routing.

Availability

SN74AHC158N is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy microcontroller bus multiplexing, and automotive diagnostic interface selector applications requiring stable component supply across long production lifecycles.

Supply support for SN74AHC158N 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 solutions for industrial, automotive, and communications markets.

The SN74AHC158N belongs to TI's AHC advanced high-speed CMOS logic family, designed specifically for low-power, high-speed digital signal routing in mixed-voltage systems where reliability and interoperability across 2–5.5 V rails are essential.

FAQ

What is the function of the G (strobe) pin on the SN74AHC158N?

The G pin is an active-high strobe input that globally disables all four multiplexer outputs. When G is high, all Y outputs are forced high regardless of A/B or data inputs. When G is low, the SN74AHC158N performs normal 2:1 selection and inversion. This enables synchronized channel blanking in time-multiplexed systems without requiring individual enable lines per channel.

Does the SN74AHC158N support 3.3 V-only operation?

Yes, the SN74AHC158N operates reliably from 2 V to 5.5 V, including nominal 3.3 V supplies. At VCC = 3.3 V, it delivers VOH ≥ 2.58 V and VOL ≤ 0.36 V under 4 mA load, meeting standard 3.3 V CMOS logic thresholds. Its input thresholds scale with VCC, ensuring correct interpretation of 3.3 V signals even when interfacing with 5 V controllers via level translation.

Are pins 3 and 11 on the SN74AHC158N functional or unused?

Pins 3 and 11 are marked "NC" (No internal connection) in the official TI datasheet for the SN74AHC158N. These pins have no internal bond wires or circuitry and must remain unconnected in PCB layout. Leaving them floating or tying them to VCC/GND may introduce parasitic capacitance or EMI coupling; best practice is to omit pads or leave them unconnected.

How does the SN74AHC158N handle unused inputs?

All unused inputs on the SN74AHC158N-including A/B, G, and any unconnected A or B lines-must be tied to either VCC or GND to prevent floating nodes. Floating CMOS inputs cause increased ICC, erratic switching, and potential device damage due to shoot-through current. TI recommends using pull-up or pull-down resistors (10 kΩ typical) rather than direct connections to minimize board-level noise coupling.

Can the SN74AHC158N be used in place of the SN74LS158?

No, the SN74AHC158N is not a direct replacement for the SN74LS158. While both are quadruple 2:1 multiplexers with identical pinouts, the LS version is bipolar TTL with 5 V-only operation, higher power consumption, and different input thresholds. The SN74AHC158N is CMOS, supports 2–5.5 V, draws far less current, and requires compatible logic families. Interfacing may require level-shifting or redesign of bias networks.