Texas Instruments SN74AHCT158NSR

Overview

SN74AHCT158NSR from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC designed for 4.5-V to 5.5-V V_CC operation. It features a common strobe (G) input, inverted outputs, TTL-voltage-compatible inputs, and operates across –40°C to 85°C. It routes one of two 4-bit data sources to four outputs based on the A/B select line - used in digital logic routing, address decoding, and bus multiplexing in industrial control systems.

For engineers reviewing the SN74AHCT158NSR datasheet, SN74AHCT158NSR pinout, SN74AHCT158NSR application, or SN74AHCT158NSR equivalent, key selection criteria include its 16-pin SOP-NS package, 8 mA output drive capability, 7.5 ns typical propagation delay (A/B → Y at 5 V, 15 pF), and compatibility with TTL-level control signals in mixed-voltage logic interfaces.

Technical Context

The SN74AHCT158NSR implements four independent 2:1 multiplexers sharing a single active-low strobe (G) and a common select input (A/B). Each channel selects either input A or B based on the logic level of A/B, with output inversion applied before driving the Y pin.

Its architecture supports synchronous enable/disable via G: when G = HIGH, all Y outputs are forced HIGH regardless of A/B or data inputs; when G = LOW, selection and inversion occur. Inputs tolerate TTL voltage thresholds (V_IL ≤ 0.8 V, V_VIH ≥ 2 V), ensuring interoperability with legacy 5-V TTL logic families.

Key Specifications

Pinout & Package

SN74AHCT158NSR is housed in a 16-pin SOP (Small Outline Package) with NS suffix, measuring 5.3 mm × 10.2 mm × 1.95 mm (height max), gull-wing leads, and RoHS-compliant NiPdAu finish. It complies with JEDEC MO-153 and is optimized for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT158NSR, SN74AHCT157N provides functional equivalence with polarity correction, while 74LVC157APW trades voltage compatibility for compactness and lower static power - making SN74AHCT158NSR the optimal choice for robust 5-V industrial control where inverted output logic aligns with existing firmware and timing constraints.

Availability

SN74AHCT158NSR is available at Aetrix Electronics and suitable for industrial PLC I/O multiplexing, legacy microcontroller address decoding, test equipment signal routing, and digital audio switching matrix applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for SN74AHCT158NSR 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 with broad industrial, automotive, and communications reach.

The SN74AHCT158NSR belongs to TI's 74AHCT logic family - engineered for TTL-compatible 5-V systems requiring low power, high noise immunity, and robust latch-up performance in harsh operating environments.

FAQ

What is the maximum operating temperature range for SN74AHCT158NSR?

The SN74AHCT158NSR is rated for continuous operation from –40°C to +85°C ambient temperature. This extended industrial temperature range ensures reliability in factory automation controllers, motor drives, and outdoor communication equipment where thermal cycling and ambient extremes are common. The device's thermal resistance (θ_JA = 64°C/W for NS package) supports adequate heat dissipation without heatsinking under typical 5-V, low-duty-cycle logic conditions.

Does SN74AHCT158NSR require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of the SN74AHCT158NSR must be held at V_CC or GND to ensure proper device operation and prevent floating-node-induced current leakage or oscillation. TI's application report SCBA004 explicitly mandates this for CMOS-based 74AHCT devices. Leaving inputs unconnected risks increased ICC, unpredictable output states, and potential ESD vulnerability - especially critical in high-reliability SN74AHCT158NSR deployments.

What is the output logic polarity of SN74AHCT158NSR?

The SN74AHCT158NSR provides inverted outputs: the Y pins deliver the logical complement of the selected input (A or B). For example, if A/B = LOW and 1A = HIGH, then 1Y = LOW. This inversion is inherent to the device's internal gate structure and is documented in the FUNCTION TABLE and logic diagram of the SCLS348J datasheet. Designers must account for this polarity in downstream logic or use complementary part SN74AHCT157NSR for non-inverting behavior.

Can SN74AHCT158NSR interface directly with 3.3-V microcontrollers?

No - SN74AHCT158NSR is a 5-V-only device with V_CC range 4.5 V to 5.5 V and TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_VIH ≥ 2.0 V). While its inputs accept 3.3-V logic HIGH (≥2.0 V), driving it from a 3.3-V MCU output risks violating V_IH margin under voltage droop or noise. Additionally, its 5-V outputs exceed 3.3-V I/O absolute maximum ratings. A level-shifter or buffer such as TXS0102 is required for safe bidirectional interfacing with 3.3-V systems.

What package variant does SN74AHCT158NSR use, and is it lead-free?

SN74AHCT158NSR uses a 16-pin SOP (Small Outline Package) with NS suffix - standardized as JEDEC MO-153, 5.3 mm × 10.2 mm body, 1.95 mm max height, and gull-wing leads. It is RoHS-compliant with NiPdAu lead finish and qualifies as lead-free per JEDEC J-STD-609. The "NS" designation specifically identifies this tape-and-reel variant of the SOP package, distinct from SOIC-D or TSSOP-PW versions in footprint and thermal profile.