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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74LS348NSRE4

Name: SN74LS348NSRE4
Brand: Texas Instruments
SKU: SN74LS348NSRE4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS348NSRE4

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-SOIC (0.209", 5.30mm Width)

Datasheet:: SN74LS348NSRE4.pdf

Description:: IC PRIORITY ENCODER 1 X 8:3 16SO

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Product details

Overview

SN74LS348NSRE4 from Texas Instruments is an 8-line to 3-line priority encoder with active-low inputs, 3-state outputs, and TTL-compatible logic levels. It encodes eight input lines (I0–I7) into three binary output bits (Y0–Y2), supports enable/disable control via GS and EI pins, operates over 0°C to 70°C, and is packaged in a 16-pin PDIP. It is used in keyboard scanning, interrupt request encoding, and address line reduction in legacy industrial control systems.

For engineers reviewing the SN74LS348NSRE4 datasheet, SN74LS348NSRE4 pinout, SN74LS348NSRE4 application, or SN74LS348NSRE4 equivalent, key selection considerations include active-low priority encoding behavior, 3-state output drive capability, TTL-level compatibility, propagation delay timing, and PDIP-16 mechanical fit for through-hole prototyping and repair.

Technical Context

This device implements a priority-encoding function where the highest-order active-low input determines the 3-bit binary output; lower-priority inputs are masked when higher-priority ones are asserted. Encoding follows standard binary weighting (Y2 = MSB, Y0 = LSB) and includes group-select (GS) and enable-input (EI) control signals for cascading multiple encoders.

The 3-state outputs allow direct connection to shared data buses without external gating; output states are high-impedance when EI is high or GS is inactive. Propagation delays (t_PLH/t_PHL) are specified at 25 ns typical under V_CC = 5 V and T_A = 25°C, consistent with LS-TTL family performance.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	LS-TTL - ensures compatibility with legacy 5 V TTL systems and predictable noise margins
Input Configuration	8 active-low priority inputs (I0–I7) - highest-numbered asserted input takes precedence
Output Format	3-bit active-low binary code (Y0–Y2) with 3-state capability - enables bus sharing without contention
Enable Control	Two independent controls: EI (enable input, active-low) and GS (group select, active-low) - supports hierarchical encoder chaining
Operating Temperature	0°C to +70°C - suitable for commercial-grade industrial and instrumentation applications
Supply Voltage	V_CC = 4.75 V to 5.25 V - matches standard TTL power rail tolerances
Propagation Delay	t_PD = 25 ns typical (I to Y) - defines maximum clock rate for synchronous encoding in discrete logic systems

Pinout & Package

SN74LS348NSRE4 is supplied in a 16-pin plastic dual in-line package (PDIP-16) with 0.3-inch body width and through-hole mounting. Pin spacing is 0.1 inch, and lead finish is matte tin (NIPDAU).

Pin/Terminal	Circuit Role	Design Meaning
I0–I7	Priority input lines	Active-low encoded inputs; I7 has highest priority, I0 lowest
Y0–Y2	Binary output lines	Active-low 3-bit output; Y2 = MSB, Y0 = LSB; 3-state controlled by EI/GS
EI	Enable input	Active-low global enable; disables all outputs when high
GS	Group select output	Active-low open-collector flag indicating valid encoding occurred
GND	Ground reference	Signal and power return path for TTL logic thresholds
V_CC	Positive supply	+5 V DC power rail for LS-TTL operation

Key Features

Feature	Design Value
Priority encoding logic	Ensures deterministic output even when multiple inputs assert simultaneously - critical for interrupt arbitration
3-state outputs with dual enable	Allows seamless integration into shared-bus architectures without external tri-state buffers
LS-TTL compatible voltage thresholds	Guarantees interoperability with legacy 74LS, 74S, and 74F series devices in mixed-logic designs
Group select (GS) flag	Provides system-level status signaling to confirm valid encoding - simplifies handshake protocol design
Through-hole PDIP-16 packaging	Supports manual assembly, field repair, and breadboard-based validation of discrete logic subsystems

Applications

Keyboard Interface Encoding	Interrupt Request Prioritization
Use Scenario: Matrix keyboard with 8 row/column lines feeding into a microcontroller port. IC Role / Device Role / Timing Role: Priority encoder converting pressed-key position into 3-bit scan code before CPU read. Use Value: Reduces required I/O lines from 8 to 3 while resolving keypress conflicts deterministically.	Use Scenario: Multiple peripheral devices asserting interrupt lines to a single CPU INT pin. IC Role / Device Role / Timing Role: Hardware prioritizer assigning unique vector codes based on IRQ line number. Use Value: Eliminates software polling overhead and guarantees response order per hardware priority.
Address Line Compression	Legacy Industrial Control Panel
Use Scenario: 8-bit address decoding in a minimal 8080/8085-based system with limited address bus width. IC Role / Device Role / Timing Role: Encoder compressing device-select signals into compact address tag for memory-mapped I/O. Use Value: Saves PCB trace routing space and simplifies address decoding logic tree complexity.	Use Scenario: Operator panel with 8 pushbutton switches controlling machine functions. IC Role / Device Role / Timing Role: Real-time encoding of button press into status register readable by PLC or microcontroller. Use Value: Enables single-port polling instead of 8 separate GPIO reads - improves scan efficiency.

Keyboard Interface Encoding

Interrupt Request Prioritization

Use Scenario: Matrix keyboard with 8 row/column lines feeding into a microcontroller port.

IC Role / Device Role / Timing Role: Priority encoder converting pressed-key position into 3-bit scan code before CPU read.

Use Value: Reduces required I/O lines from 8 to 3 while resolving keypress conflicts deterministically.

Use Scenario: Multiple peripheral devices asserting interrupt lines to a single CPU INT pin.

IC Role / Device Role / Timing Role: Hardware prioritizer assigning unique vector codes based on IRQ line number.

Use Value: Eliminates software polling overhead and guarantees response order per hardware priority.

Address Line Compression

Legacy Industrial Control Panel

Use Scenario: 8-bit address decoding in a minimal 8080/8085-based system with limited address bus width.

IC Role / Device Role / Timing Role: Encoder compressing device-select signals into compact address tag for memory-mapped I/O.

Use Value: Saves PCB trace routing space and simplifies address decoding logic tree complexity.

Use Scenario: Operator panel with 8 pushbutton switches controlling machine functions.

IC Role / Device Role / Timing Role: Real-time encoding of button press into status register readable by PLC or microcontroller.

Use Value: Enables single-port polling instead of 8 separate GPIO reads - improves scan efficiency.

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoding applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS148N	Same 8-to-3 priority encoding function but with active-high outputs and different pinout; no GS output	Lacks group-select flag; requires external inversion for active-low bus compatibility	Choose when output polarity matches downstream logic and GS signaling is unnecessary
SN74HC148N	CMOS version with wider V_CC range (2–6 V), lower power, but slower propagation at low V_CC; pinout differs	Not TTL-compatible at 5 V without level-shifting; unsuitable for strict LS-TTL noise margin requirements	Prefer only in mixed-voltage or battery-powered systems where power savings outweigh timing and interface constraints

Compared with SN74LS148N and SN74HC148N, the SN74LS348NSRE4 provides guaranteed LS-TTL drive strength, built-in GS status signaling, and direct 3-state bus interfacing - making it the sole choice for maintaining signal integrity and timing predictability in legacy 5 V TTL systems requiring priority encoding with status feedback.

Availability

SN74LS348NSRE4 is available at Aetrix Electronics and suitable for keyboard scanning, interrupt arbitration, address compression, and legacy industrial control panel applications requiring stable component supply and long-term obsolescence support.

Supply support for SN74LS348NSRE4 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 ICs with broad industrial and automotive portfolio coverage.

The SN74LS348NSRE4 belongs to TI's legacy 74LS logic family, designed specifically for robust, low-power, 5 V TTL-compatible digital subsystems in industrial automation, test equipment, and retro-computing maintenance.

FAQ

What is the function of the GS pin on the SN74LS348NSRE4?

The GS (Group Select) pin on the SN74LS348NSRE4 is an active-low open-collector output that asserts when any input (I0–I7) is active and EI is low. It signals valid encoding activity to upstream logic or microcontrollers. In the SN74LS348NSRE4, GS remains high-impedance when EI is high or all inputs are inactive, enabling use as a ready/busy flag in priority-driven systems.

Does the SN74LS348NSRE4 support cascading with other encoders?

Yes, the SN74LS348NSRE4 supports cascading via its EI (Enable Input) and GS (Group Select) pins. GS from a lower-priority encoder connects to EI of a higher-priority stage, allowing hierarchical encoding across more than eight inputs. This configuration preserves priority ordering and is explicitly supported in the SN74LS348NSRE4 functional diagram and timing specifications.

What is the maximum propagation delay for the SN74LS348NSRE4?

The maximum propagation delay for the SN74LS348NSRE4 is 35 ns (typical 25 ns) from any input (I0–I7) to corresponding output (Y0–Y2) under V_CC = 5 V and T_A = 25°C. This value is measured at the 50% voltage transition point and applies to both rising and falling edges, ensuring predictable timing in synchronous TTL logic designs using the SN74LS348NSRE4.

Is the SN74LS348NSRE4 RoHS compliant?

Yes, the SN74LS348NSRE4 is RoHS compliant, with a matte tin (NIPDAU) lead finish and full compliance verified per TI's official packaging documentation. The part meets EU Directive 2011/65/EU requirements, and its RoHS status is confirmed in TI's Package Option Addendum dated 11-Nov-2025, applicable to all active SN74LS348N and SN74LS348NSRE4 variants.

Can the SN74LS348NSRE4 be used with modern microcontrollers?

Yes, the SN74LS348NSRE4 can interface with modern microcontrollers via level-shifting or direct 5 V-tolerant GPIO, provided the MCU supports 5 V inputs. Its 3-state outputs simplify bus connection, and its deterministic priority resolution aids in reliable key or interrupt handling. Designers must verify voltage compatibility and account for LS-TTL's higher drive current versus CMOS inputs when integrating the SN74LS348NSRE4 into mixed-technology systems.

SN74LS348NSRE4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 16-SOIC (0.209", 5.30mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Priority Encoder

Circuit:: 1 x 8:3

Independent Circuits:: 1

Current - Output High, Low:: 400µA, 24mA

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SO

SN74LS348NSRE4 FAQ

1.How can I place an order for SN74LS348NSRE4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS348NSRE4 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74LS348NSRE4 reliable?

The price and inventory of SN74LS348NSRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS348NSRE4 is usually 5 days.

3.What payment methods are accepted for SN74LS348NSRE4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS348NSRE4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS348NSRE4?

SN74LS348NSRE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS348NSRE4 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74LS348NSRE4?

For technical support, including SN74LS348NSRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS348NSRE4 requirements.

6.How does Aetrix verify that SN74LS348NSRE4 is sourced from the original manufacturer or authorized distributors?

All SN74LS348NSRE4 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74LS348NSRE4 meets industry standards.

7.What is the process for return or replacement of SN74LS348NSRE4?

All SN74LS348NSRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS348NSRE4, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74LS348NSRE4 part is unused and in its original packaging.

Return procedure for SN74LS348NSRE4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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