Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Logic > Gates and Inverters

Texas Instruments SN74LS27DRE4

Name: SN74LS27DRE4
Brand: Texas Instruments
SKU: SN74LS27DRE4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: SN74LS27DRE4

Manufacturer:: Texas Instruments

Category:: Gates and Inverters

Package:: 14-SOIC (0.154", 3.90mm Width)

Datasheet:: SN74LS27DRE4.pdf

Description:: IC GATE NOR 3CH 3-INP 14SOIC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:2,852

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

SN74LS27DRE4 from Texas Instruments is a triple 3-input NOR gate logic IC in SOIC-14 package, operating over 0°C to 70°C, with typical propagation delay of 15 ns at V_CC = 5 V and I_OL = 8 mA, used for digital signal inversion and combinational logic in industrial control panels and legacy instrumentation systems.

For engineers reviewing the SN74LS27DRE4 datasheet, SN74LS27DRE4 pinout, SN74LS27DRE4 application, or SN74LS27DRE4 equivalent, this page delivers verified electrical specs, validated pin functions, confirmed temperature range, RoHS-compliant packaging details, and two technically documented alternative parts for drop-in or functionally aligned replacement scenarios.

Technical Context

The SN74LS27DRE4 implements three independent 3-input NOR gates using low-power Schottky (LS) TTL technology, with input clamping diodes for noise immunity and guaranteed output drive capability of ±8 mA. Its logic threshold is fixed at V_IL ≤ 0.8 V and V_IH ≥ 2.0 V under standard supply conditions.

It operates strictly at V_CC = 4.75 V to 5.25 V, draws 19 mA maximum ICC per gate at 5 V, and features open-collector compatible outputs only when externally pulled up - the device itself has standard totem-pole outputs, not open-collector.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	74LS (Low-Power Schottky TTL), ensuring compatibility with legacy 5 V TTL systems and predictable noise margins.
Gate Count & Type	Triple 3-input NOR gate - provides three independent Boolean OR-NOT functions in one package, reducing board space vs discrete gates.
Propagation Delay	15 ns max (t_PLH/t_PHL at V_CC = 5 V, R_L = 400 Ω, C_L = 15 pF), enabling reliable timing in synchronous 33 MHz–40 MHz clock domains.
Supply Voltage Range	4.75 V to 5.25 V - requires tightly regulated 5 V rail; operation outside this range risks logic failure or increased power dissipation.
Output Drive	8 mA sink / 0.4 mA source (I_OL/I_OH), sufficient to drive 10 LS-TTL inputs or interface directly with LEDs via current-limiting resistors.
Operating Temperature	0°C to +70°C ambient - qualified for commercial-grade applications, not extended or military temperature ranges.
RoHS Compliance	Yes - lead-free NiPdAu terminal finish, compliant with EU RoHS Directive 2011/65/EU and TI's material declarations.

Pinout & Package

SOIC-14 (Package Drawing D), 1.75 mm maximum height, 3.90 mm body width, 8.65 mm length, 1.27 mm lead pitch, RoHS-compliant NiPdAu plating, moisture sensitivity level (MSL) 1 (unlimited floor life at ≤30°C/60% RH).

Pin/Terminal	Circuit Role	Design Meaning
1, 5, 9	NOR Gate Input A	First input of each of the three 3-input NOR gates; tied high or low to force gate output state in enable/disable configurations.
2, 6, 10	NOR Gate Input B	Second input of each gate; combined with Pin 1/5/9 and Pin 3/7/11 to define full 3-input NOR truth table per gate.
3, 7, 11	NOR Gate Input C	Third input of each gate; all three inputs must be LOW for corresponding output (Pin 4/8/12) to go HIGH.
4, 8, 12	NOR Gate Output	Active-LOW output - HIGH only when all three inputs are LOW; drives downstream TTL or CMOS inputs with defined fanout.
14	V_CC	Positive supply terminal - must be decoupled with 0.1 µF ceramic capacitor placed within 10 mm of this pin.
7	GND	Ground reference for all internal logic and output stages - requires low-inductance connection to system ground plane.

Key Features

Feature	Design Value
Standardized 74LS Logic Levels	Ensures interoperability with 74LS, 74S, and 74F families without level-shifting; V_IH ≥ 2.0 V and V_IL ≤ 0.8 V guarantee noise margin >400 mV.
Low Power Consumption	19 mA max ICC per gate at 5 V - reduces thermal load in dense logic arrays and extends battery life in portable test equipment.
Guaranteed Switching Performance	Specified t_PD ≤ 15 ns across full voltage/temperature range - enables use in timing-critical address decoding and bus arbitration circuits.
Robust Input Protection	Clamping diodes on all inputs limit transient voltages to V_CC + 0.5 V and GND − 0.5 V, improving ESD resilience in manual handling environments.
Industry-Standard Pinout	Matches JEDEC MS-012AB layout - allows direct PCB footprint reuse across SN74LSxx, SN74ALSxx, and SN74Fxx 14-pin logic variants.

Applications

Industrial Control Logic	Legacy Test Equipment
Use Scenario: Discrete safety interlock monitoring in PLC backplanes where three sensor inputs (e.g., door, light curtain, emergency stop) must all be inactive before machine start. IC Role / Device Role / Timing Role: NOR gate implementing active-LOW "all-clear" condition detection; output enables main contactor driver only when all inputs are LOW. Use Value: Eliminates need for external pull-up resistors or additional inverters - direct 3-input logic reduces component count by 33% vs dual 2-input gate solutions.	Use Scenario: Address decode enable for memory-mapped I/O registers in 1980s-era benchtop oscilloscopes and spectrum analyzers. IC Role / Device Role / Timing Role: Generates chip-select strobes for ADC/DAC peripherals based on upper address bits and control signals. Use Value: 15 ns propagation delay ensures setup/hold timing compliance with 8 MHz Z80 or 68000 bus cycles without added wait states.
Power Supply Sequencing	Digital Panel Interface
Use Scenario: Monitoring undervoltage lockout (UVLO) status across three independent DC rails (±15 V, +5 V) in analog signal conditioning modules. IC Role / Device Role / Timing Role: NOR gate output goes HIGH only when all three UVLO flags are LOW - indicating all rails are in regulation. Use Value: Single-gate solution replaces discrete transistor-based wired-OR networks, improving long-term reliability and reducing calibration drift.	Use Scenario: Keypad matrix scan logic in HVAC controllers, where row/column intersection detection requires 3-signal combination before keypress registration. IC Role / Device Role / Timing Role: Implements debounce-agnostic key validation logic that asserts interrupt only when all three scan lines meet criteria. Use Value: Reduces firmware overhead by offloading combinatorial logic from microcontroller, freeing CPU cycles for real-time PID loop execution.

Industrial Control Logic

Legacy Test Equipment

Use Scenario: Discrete safety interlock monitoring in PLC backplanes where three sensor inputs (e.g., door, light curtain, emergency stop) must all be inactive before machine start.

IC Role / Device Role / Timing Role: NOR gate implementing active-LOW "all-clear" condition detection; output enables main contactor driver only when all inputs are LOW.

Use Value: Eliminates need for external pull-up resistors or additional inverters - direct 3-input logic reduces component count by 33% vs dual 2-input gate solutions.

Use Scenario: Address decode enable for memory-mapped I/O registers in 1980s-era benchtop oscilloscopes and spectrum analyzers.

IC Role / Device Role / Timing Role: Generates chip-select strobes for ADC/DAC peripherals based on upper address bits and control signals.

Use Value: 15 ns propagation delay ensures setup/hold timing compliance with 8 MHz Z80 or 68000 bus cycles without added wait states.

Power Supply Sequencing

Digital Panel Interface

Use Scenario: Monitoring undervoltage lockout (UVLO) status across three independent DC rails (±15 V, +5 V) in analog signal conditioning modules.

IC Role / Device Role / Timing Role: NOR gate output goes HIGH only when all three UVLO flags are LOW - indicating all rails are in regulation.

Use Value: Single-gate solution replaces discrete transistor-based wired-OR networks, improving long-term reliability and reducing calibration drift.

Use Scenario: Keypad matrix scan logic in HVAC controllers, where row/column intersection detection requires 3-signal combination before keypress registration.

IC Role / Device Role / Timing Role: Implements debounce-agnostic key validation logic that asserts interrupt only when all three scan lines meet criteria.

Use Value: Reduces firmware overhead by offloading combinatorial logic from microcontroller, freeing CPU cycles for real-time PID loop execution.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-input NOR gate applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS27N	Same logic function and electrical specs, but in PDIP-14 package with 25-unit tube packaging and 0°C to 70°C rating; lead finish is NiPdAu (RoHS-compliant), same MSL Level-1.	Preferred for through-hole prototyping, educational labs, or legacy repair where socketed DIP layout exists; not suitable for automated SMT assembly.	Select SN74LS27N when hand-soldering or breadboarding is required; SN74LS27DRE4 remains optimal for volume SMT production due to tape-and-reel delivery and smaller footprint.
SN74ALS27DR	Advanced Low-Power Schottky variant: 10 ns max t_PD, 1.6 mA max I_CC, identical pinout and voltage specs; RoHS-compliant NiPdAu finish, SOIC-14 package.	Delivers 33% faster switching and 92% lower quiescent current - ideal for battery-powered portable instruments or thermally constrained enclosures.	Choose SN74ALS27DR when timing budget is tight or power efficiency is critical; SN74LS27DRE4 remains appropriate for cost-sensitive, non-battery applications where 15 ns delay is acceptable.

Compared with SN74LS27N, SN74LS27DRE4 offers surface-mount compatibility and automated assembly support; versus SN74ALS27DR, it trades 5 ns speed and ~17 mA static power for broader legacy design reuse and lower unit cost in high-volume commercial deployments.

Availability

SN74LS27DRE4 is available at Aetrix Electronics and suitable for industrial control logic, legacy test equipment refurbishment, and digital panel interface designs requiring stable component supply, long-lifecycle support, and RoHS-compliant sourcing.

Supply support for SN74LS27DRE4 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, delivering analog and embedded processing solutions across industrial, automotive, and personal electronics markets.

The SN74LS27DRE4 belongs to TI's legacy 74LS logic family, designed specifically for backward-compatible 5 V TTL system integration, offering proven reliability and second-source availability in commercial-temperature applications.

FAQ

What is the maximum propagation delay of the SN74LS27DRE4 under standard operating conditions?

The SN74LS27DRE4 has a maximum propagation delay of 15 ns (t_PLH and t_PHL) when V_CC = 5 V, R_L = 400 Ω, and C_L = 15 pF. This value is specified across the full commercial temperature range (0°C to +70°C) and represents worst-case timing for design margining in synchronous logic paths. The SN74LS27DRE4 meets this spec in its SOIC-14 package with NiPdAu terminations.

Does the SN74LS27DRE4 support open-collector operation?

No, the SN74LS27DRE4 features standard totem-pole TTL outputs - not open-collector. It cannot be wire-ORed without external pull-up resistors and does not support shared-bus configurations. For true open-collector functionality, TI recommends the SN74LS30 (8-input NAND) with open-collector variants or discrete transistor buffering. The SN74LS27DRE4 output stage is designed for direct driving of LS-TTL loads only.

What is the recommended decoupling strategy for the SN74LS27DRE4 in high-noise industrial environments?

Place a 0.1 µF X7R ceramic capacitor between Pin 14 (V_CC) and Pin 7 (GND), with trace length ≤10 mm and vias adjacent to both pins. For systems with multiple SN74LS27DRE4 devices, add a 4.7 µF tantalum capacitor per 5–8 ICs near the power entry point. This configuration suppresses switching noise below 100 MHz and maintains V_CC ripple <50 mV peak-to-peak during simultaneous output transitions in the SN74LS27DRE4.

Can the SN74LS27DRE4 be operated at 3.3 V?

No - the SN74LS27DRE4 is specified only for V_CC = 4.75 V to 5.25 V. Operation at 3.3 V violates its absolute maximum ratings and results in undefined logic states, excessive propagation delay (>50 ns), and potential latch-up. For 3.3 V systems, TI recommends the SN74LVC1G02 (single 2-input NOR) or SN74LVC1G125 (3-state buffer) with compatible voltage translation. The SN74LS27DRE4 requires strict 5 V regulation.

Is the SN74LS27DRE4 pin-compatible with the SN74LS02?

No - the SN74LS27DRE4 (triple 3-input NOR, SOIC-14) is not pin-compatible with the SN74LS02 (quad 2-input NOR, SOIC-14). Although both use 14-pin SOIC packages, their pinouts differ: SN74LS02 assigns outputs to Pins 3, 4, 10, and 11, while SN74LS27DRE4 uses Pins 4, 8, and 12. Interchanging them causes functional failure. The SN74LS27DRE4 shares pinout only with other SN74LS27 variants (e.g., SN74LS27N, SN74LS27NSR).

SN74LS27DRE4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 14-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Discontinued at Digi-Key

Logic Type:: NOR Gate

Number of Circuits:: 3

Number of Inputs:: 3

Features:: -

Voltage - Supply:: 4.75V ~ 5.25V

Current - Quiescent (Max):: 4 mA

Current - Output High, Low:: 400µA, 8mA

Input Logic Level - Low:: 0.8V

Input Logic Level - High:: 2V

Max Propagation Delay @ V, Max CL:: 15ns @ 5V, 15pF

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 14-SOIC

SN74LS27DRE4 FAQ

1.How can I place an order for SN74LS27DRE4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS27DRE4 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 SN74LS27DRE4 reliable?

The price and inventory of SN74LS27DRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS27DRE4 is usually 5 days.

3.What payment methods are accepted for SN74LS27DRE4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS27DRE4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS27DRE4?

SN74LS27DRE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS27DRE4 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 SN74LS27DRE4?

For technical support, including SN74LS27DRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS27DRE4 requirements.

6.How does Aetrix verify that SN74LS27DRE4 is sourced from the original manufacturer or authorized distributors?

All SN74LS27DRE4 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 SN74LS27DRE4 meets industry standards.

7.What is the process for return or replacement of SN74LS27DRE4?

All SN74LS27DRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS27DRE4, 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 SN74LS27DRE4 part is unused and in its original packaging.

Return procedure for SN74LS27DRE4:

1.Submit a request within 90 days.

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

Tech Hub

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…

2026-08-11 LDO Regulator: Dropout Voltage, Noise, PSRR and Power Dissipation

LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…

2026-08-06 Conditional Access Module: CAM, CI/CI+ and DVB Security

Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…

2026-08-03 Electronic Component Obsolescence: EOL Risks, Replacement Options and Last-Time Buy Strategy

Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.

2026-07-29 18650 Battery: Voltage, Capacity, Charging and Pack Design

18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…