Texas Instruments SN74LS157DRG4

Overview

SN74LS157DRG4 from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer in a 16-pin SOIC package, operating at 0°C to 70°C, with typical propagation delay of 15 ns and supply current of 19 mA at V_CC = 5 V. It performs digital signal routing in bus management and address/data path selection for microprocessor systems.

For engineers reviewing the SN74LS157DRG4 datasheet, SN74LS157DRG4 pinout, SN74LS157DRG4 application, or SN74LS157DRG4 equivalent, key selection criteria include its TTL-compatible input thresholds, complementary enable-controlled output gating, single-supply 5-V operation, and compatibility with legacy LS logic families in industrial control and test equipment design.

Technical Context

The SN74LS157DRG4 integrates four independent 2:1 multiplexers sharing a common strobe (enable) input and complementary outputs. Each channel selects between two data inputs (A or B) based on the select line state, with active-low enable asserting high-impedance outputs when inactive.

It uses bipolar transistor–transistor logic (TTL) architecture with Schottky-clamped transistors to achieve speed-power trade-offs characteristic of the 74LS family: guaranteed 15 ns max t_PD, fan-out of 20 LS-TTL loads, and noise immunity of 0.4 V min V_IL and 1.5 V min V_IH.

Key Specifications

Pinout & Package

SN74LS157DRG4 is housed in a 16-pin small-outline integrated circuit (SOIC-D) package with 1.27-mm pitch, 3.9-mm body width, and 1.75-mm maximum height. Pin 1 is located at the top-left corner with notch or dot marking.

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 SN74LS157DRG4, SN74LS158DR offers identical timing and packaging but inverted logic polarity, while SN74HC157DR trades speed and drive strength for CMOS power efficiency and wider voltage range-making each suitable only for specific voltage, noise, and signal-polarity contexts.

Availability

SN74LS157DRG4 is available at Aetrix Electronics and suitable for microprocessor bus steering, test equipment signal routing, digital logic function synthesis, and legacy system interface bridging requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74LS157DRG4 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 market reach.

The SN74LS157DRG4 belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-cost digital signal routing in commercial-grade control systems, instrumentation, and retrofitted computing platforms.

FAQ

What is the maximum clock frequency supported by SN74LS157DRG4?

The SN74LS157DRG4 does not operate on a clock signal-it is a combinational logic device with no internal clock. Its usable data rate depends on propagation delay (15 ns max) and system setup/hold timing; for clean 2:1 selection in synchronous buses, it supports effective toggle rates up to approximately 33 MHz when paired with compatible drivers and loads. The SN74LS157DRG4 itself imposes no clock limitation.

Can SN74LS157DRG4 be used with 3.3-V logic inputs?

No-SN74LS157DRG4 requires TTL-compatible input voltages: V_IH ≥ 2.0 V and V_IL ≤ 0.8 V at V_CC = 5 V. A 3.3-V logic high may fall below the guaranteed V_IH threshold, risking unreliable switching. For 3.3-V systems, consider SN74LVC157A or level-shifting buffers. The SN74LS157DRG4 is strictly a 5-V device.

Does SN74LS157DRG4 have ESD protection diodes on its inputs?

Yes-the SN74LS157DRG4 includes internal clamp diodes from each input to V_CC and GND, rated for ±2 kV HBM per JEDEC JESD22-A114. These protect against transient overvoltage during handling and board insertion, but do not replace system-level ESD safeguards. Always observe proper grounding and static-safe practices when handling the SN74LS157DRG4.

Is SN74LS157DRG4 pin-compatible with SN74LS157N (PDIP package)?

Yes-SN74LS157DRG4 (SOIC-D) and SN74LS157N (PDIP-N) share identical pin numbering, signal assignments, and electrical specifications. Both are 16-pin devices with the same logic function, timing, and DC characteristics. Only the package type differs; PCB layout must accommodate SOIC footprint versus DIP through-hole mounting. The SN74LS157DRG4 is a direct functional and pinout replacement for SN74LS157N in surface-mount designs.

What is the recommended bypass capacitor for SN74LS157DRG4?

A 0.1-µF ceramic capacitor placed as close as possible (≤10 mm) to the V_CC (pin 16) and GND (pin 8) pins is recommended for SN74LS157DRG4. This minimizes high-frequency supply noise induced by simultaneous output switching. For systems with heavy bus loading or high-speed cycling, add a bulk 4.7-µF tantalum capacitor nearby. Proper decoupling ensures stable operation of the SN74LS157DRG4 across its full temperature and load range.