Texas Instruments SN74LS157NSR

Overview

SN74LS157NSR from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer in a 16-pin SOP (NS) package, operating from 4.75 V to 5.25 V with typical propagation delay of 15 ns and fan-out of 20 LS-TTL loads. It performs logic-level signal routing in digital control systems, such as address/data bus switching in microprocessor peripheral interfaces.

For engineers reviewing the SN74LS157NSR datasheet, SN74LS157NSR pinout, SN74LS157NSR application, or SN74LS157NSR equivalent, key selection criteria include its TTL-compatible input thresholds, complementary enable control (1G̅), single-bit select line (S), and guaranteed operation across 0°C to 70°C ambient temperature.

Technical Context

The SN74LS157NSR integrates four independent 2:1 multiplexers sharing one common data select (S) and one active-low enable (1G̅). Each channel routes either A or B input to Y output based on S state when 1G̅ is low; all Y outputs go high-impedance when 1G̅ is high.

It uses bipolar Schottky TTL process technology, delivering standard LS logic voltage levels (VIH = 2.0 V min, VIL = 0.8 V max), DC output drive capability of –0.4 mA (high) / 8 mA (low), and noise immunity via hysteresis-free but tightly specified input thresholds.

Key Specifications

Pinout & Package

SOP (NS) package: 16-pin small-outline plastic package, 1.27 mm pitch, 8.45 mm × 10.55 mm body size, 2.00 mm max height, tape-and-reel packaging (2000 pcs/reel), RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS157N and SN74LS157DR, the SN74LS157NSR provides identical logic behavior and timing in a narrower SOP package optimized for high-density surface-mount layouts, with no change to control signaling or power requirements.

Availability

SN74LS157NSR is available at Aetrix Electronics and suitable for microprocessor bus arbitration, industrial PLC I/O expansion, digital test equipment signal routing, and legacy instrumentation interface logic requiring stable component supply across commercial temperature range.

Supply support for SN74LS157NSR 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 products with global manufacturing and quality certification infrastructure.

The SN74LS157NSR belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost digital signal routing in commercial-grade industrial control, test, and computing equipment.

FAQ

What is the maximum clock frequency supported by SN74LS157NSR?

The SN74LS157NSR is not a clocked device-it has no internal clock and operates asynchronously. Its usable data rate depends on propagation delay (15 ns typical) and system setup/hold timing. In practice, it reliably supports data switching up to approximately 30 MHz in well-designed PCB layouts with controlled trace lengths and proper termination.

Does SN74LS157NSR support 3.3 V logic interfaces?

No. The SN74LS157NSR is a 5 V-only TTL device with VIH minimum of 2.0 V and VIL maximum of 0.8 V. Direct connection to 3.3 V CMOS outputs may result in marginal or unreliable high-level recognition. A level-shifter or buffer such as SN74LVC1T45 is required for robust 3.3 V ↔ 5 V interfacing.

Can SN74LS157NSR outputs drive LEDs directly?

No. The SN74LS157NSR output sink current is rated at 8 mA (IOL), which is insufficient for most indicator LEDs requiring 10–20 mA. Additionally, its high-state output current is only –0.4 mA, making it unsuitable for high-side LED drive. Use a transistor buffer or dedicated LED driver IC when connecting to LEDs.

Is SN74LS157NSR pin-compatible with SN74LS158NSR?

No. Although both are 16-pin SOP devices, SN74LS157NSR is a quad 2:1 multiplexer, while SN74LS158NSR is a quad 2-input NAND gate with different pin assignments-including distinct enable and output configurations. Their pinouts are not interchangeable; PCB layout and firmware control logic must be redesigned for substitution.

What is the meaning of the "NS" in SN74LS157NSR?

The "NS" in SN74LS157NSR denotes the SOP (Small Outline Package) variant with 16 pins, standardized under TI's package drawing NS0016A. It specifies a 1.27 mm lead pitch, 8.45 mm × 10.55 mm body, and RoHS-compliant NiPdAu plating-distinct from "D" (SOIC) and "N" (PDIP) variants of the same logic function.