Texas Instruments SN74LS158D

Overview

SN74LS158D from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer in a 16-pin SOIC package, operating from 0°C to 70°C with typical propagation delay of 15 ns and supply current of 19 mA at 5 V. It performs logic-level signal routing in digital control systems, enabling selection between two input groups (A/B) under common select and enable control for industrial sequencers and test equipment.

For engineers reviewing the SN74LS158D datasheet, SN74LS158D pinout, SN74LS158D application, or SN74LS158D equivalent, this page delivers verified functional identity, confirmed pin roles, temperature-rated performance, TTL-compatible drive capability, and direct alternative options for legacy LS logic redesigns.

Technical Context

The SN74LS158D implements four independent 2:1 multiplexers sharing a single active-low strobe (G̅) and dual select inputs (S0, S1), where S0/S1 jointly determine which of two input pairs (1A/1B, 2A/2B, 3A/3B, 4A/4B) routes to corresponding outputs (1Y, 2Y, 3Y, 4Y). All inputs and outputs are TTL-compatible with guaranteed VIH ≥ 2.0 V and VIL ≤ 0.8 V.

It uses bipolar Schottky-clamped transistor logic for speed-power trade-off optimization, delivering 15 ns typical tPD at 5 V while maintaining fan-out of 20 TTL loads. The device lacks internal latching or three-state output control - outputs are always active when G̅ = LOW and follow selected inputs with standard TTL voltage thresholds.

Key Specifications

Pinout & Package

SN74LS158D is housed in a 16-pin Small Outline Integrated Circuit (SOIC) package (Package Drawing D), 7.5 mm wide, with 1.27 mm pitch and 2.00 mm max height. Pin 1 is marked by a beveled corner or notch orientation per JEDEC MS-012.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS158D, SN74LS157N offers identical logic behavior in a through-hole package ideal for hand-soldered development, while SN74LS158DR provides identical SOIC functionality with active manufacturing support, RoHS compliance, and tape-and-reel packaging - making it the recommended choice for production builds.

Availability

SN74LS158D is available at Aetrix Electronics and suitable for industrial control sequencing, legacy test equipment signal routing, digital logic prototyping, and embedded system address decoding requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS158D 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 specializing in analog, embedded processing, and logic ICs with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74LS158D belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost digital signal routing in commercial-grade systems where TTL compatibility and deterministic timing are essential.

FAQ

What is the function of the SN74LS158D in digital circuits?

The SN74LS158D is a quad 2-line-to-1-line data selector/multiplexer that routes one of two input signals per channel to its corresponding output, controlled by shared select (S0, S1) and strobe (G̅) inputs. It performs parallel signal selection in TTL-based systems, enabling compact implementation of data switching, address decoding, and test-mode routing without external latches or buffers. Its design ensures consistent timing and fan-out across all four channels.

Is SN74LS158D still in active production?

No, SN74LS158D is marked as Obsolete in TI's official packaging documentation. However, Aetrix Electronics maintains legacy inventory and offers traceable, tested units for repair and continuity support. For new designs, SN74LS158DR - an active, RoHS-compliant SOIC variant with identical pinout and functionality - is the recommended replacement.

Can SN74LS158D be used in place of SN74LS157?

No - SN74LS158D and SN74LS157 are functionally distinct. SN74LS157 is a quad 2-input multiplexer with complementary outputs (Y and Y̅), while SN74LS158D provides only true outputs (Y) and uses inverted-enable logic (G̅). Their truth tables, pin assignments, and output behavior differ; substituting one for the other will cause incorrect logic states unless circuit-level adaptation is performed.

What is the maximum clock frequency supported by SN74LS158D?

The SN74LS158D does not operate on a clock signal - it is a combinational logic device with no internal clock or latch. Its usable data rate depends on propagation delay (15 ns typical) and system timing margins. In practice, it supports reliable operation in synchronous systems up to approximately 30 MHz for non-critical path selection, assuming proper setup/hold times are met at inputs and downstream loads are within fan-out limits.

Does SN74LS158D support three-state outputs?

No, SN74LS158D does not feature three-state outputs. When enabled (G̅ = LOW), outputs actively drive HIGH or LOW depending on selected inputs. When disabled (G̅ = HIGH), all outputs are forced HIGH (not high-impedance). For bus-sharing applications requiring high-Z states, alternatives like SN74LS251 or SN74LS151 with explicit three-state control must be used instead of SN74LS158D.