Texas Instruments SN74LS157NE4

Overview

SN74LS157NE4 from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer in a 16-pin PDIP 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, bus management, and address/data path selection in legacy microprocessor interfaces.

For engineers reviewing the SN74LS157NE4 datasheet, SN74LS157NE4 pinout, SN74LS157NE4 application, or SN74LS157NE4 equivalent, key selection criteria include its TTL-compatible input thresholds, complementary enable control (1G), dual-output structure (1Y–4Y), and guaranteed operation across 0°C to 70°C ambient temperature-critical for industrial control panels and retro-computing hardware upgrades.

Technical Context

This device implements four independent 2:1 multiplexers sharing a common data-select (S) and output-enable (1G) control. Each channel routes either A or B input to Y output based on S logic level, with active-low enable asserting high-impedance outputs when disabled.

All inputs are TTL-compatible with VIH = 2.0 V min and VIL = 0.8 V max; outputs drive standard LS-TTL loads with VOH = 2.7 V min at IOL = 8 mA and VOL = 0.5 V max at IOH = 400 µA. No internal latching or clocking is present-operation is purely combinational.

Key Specifications

Pinout & Package

SN74LS157NE4 uses a 16-pin plastic dual in-line package (PDIP-N), 0.300-inch wide body, with 0.100-inch lead pitch and through-hole mounting. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.

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 SN74LS157NE4 offers identical logic functionality and DC/AC performance but provides TI's enhanced Pb-free plating specification (E4) and tube packaging optimized for manual prototyping, repair, and low-volume industrial builds.

Availability

SN74LS157NE4 is available at Aetrix Electronics and suitable for industrial control logic, legacy microprocessor bus interface, and digital test equipment requiring stable component supply with long-term obsolescence mitigation.

Supply support for SN74LS157NE4 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and automotive reach.

The SN74LS157NE4 belongs to TI's legacy 74LS logic family, designed specifically for backward compatibility with 1970s–1990s digital systems requiring robust TTL signaling, deterministic timing, and through-hole manufacturability.

FAQ

What is the function of the 1G pin on the SN74LS157NE4?

The 1G pin is the active-low output enable control for the SN74LS157NE4. When 1G is high, all four Y outputs enter a high-impedance (Hi-Z) state regardless of the S or input states-enabling bus sharing in multi-device configurations. When 1G is low, the multiplexer operates normally, routing selected inputs to outputs. This behavior is confirmed in TI's SN74LS157 datasheet Section 7.3.

Can SN74LS157NE4 operate with a 3.3 V supply?

No, the SN74LS157NE4 is not specified for 3.3 V operation. Its absolute maximum supply voltage is 5.5 V, and minimum recommended VCC is 4.75 V per TI's datasheet. At 3.3 V, input thresholds become unreliable and output drive capability collapses-use SN74LVC157 or similar 3.3 V logic families instead. The SN74LS157NE4 requires a regulated +5 V rail.

Is SN74LS157NE4 pin-compatible with SN74LS158?

No, SN74LS157NE4 is not pin-compatible with SN74LS158. While both are 16-pin PDIP multiplexers, SN74LS158 implements dual 4:1 multiplexers with different pin assignments for inputs, selects, and outputs. Pinouts differ significantly-e.g., SN74LS157NE4 uses pins 2–3, 4–5, 10–11, 12–13 for A/B inputs, whereas SN74LS158 assigns them differently. Direct substitution will cause functional failure.

What does the "E4" suffix indicate in SN74LS157NE4?

Per TI's packaging nomenclature, the "E4" suffix in SN74LS157NE4 denotes an enhanced Pb-free terminal finish compliant with JEDEC J-STD-020 moisture sensitivity standards and TI's internal plating specification revision. It confirms NiPdAu (nickel-palladium-gold) plating over copper leads, optimized for solderability and long-term reliability in through-hole assembly. The core SN74LS157NE4 die and logic function remain unchanged from SN74LS157N.

Does SN74LS157NE4 support latched or registered operation?

No, the SN74LS157NE4 is purely combinational logic with no internal storage elements. Its outputs respond asynchronously to changes in S, 1G, or input signals-there is no clock input, latch enable, or edge-triggered behavior. Any timing-critical use requires external synchronization, as confirmed by the absence of clock-related parameters in TI's SN74LS157 datasheet timing diagrams.