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Home > Products > Integrated Circuits (ICs) > Logic > Buffers, Drivers, Receivers, Transceivers

Texas Instruments SN74F240NSR

Name: SN74F240NSR
Brand: Texas Instruments
SKU: SN74F240NSR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74F240NSR

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-SOIC (0.209", 5.30mm Width)

Datasheet:: SN74F240NSR.pdf

Description:: IC BUFFER INVERT 5.5V 20SO

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Product details

Overview

SN74F240NSR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for memory address driving and bus interfacing in TTL-compatible systems. It features two independent 4-bit sections, each with active-low output-enable (OE) control, 5 V supply operation, ±64 mA low-level output drive, and propagation delays as low as 1.2 ns (tPHL). It operates from 0°C to 70°C and is packaged in a 20-pin SOP (NS) package.

For engineers reviewing the SN74F240NSR datasheet, SN74F240NSR pinout, SN74F240NSR application, or SN74F240NSR equivalent, key selection criteria include 3-state bus-driving capability, TTL-level compatibility, dual-section independent enable control, high-current sinking performance, and industrial-temperature SOIC-compatible packaging.

Technical Context

The SN74F240NSR implements two independent 4-bit noninverting buffer sections, each with dedicated active-low output-enable inputs (1OE and 2OE), enabling selective bus isolation without signal inversion. Its TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V) and output voltage levels (VOH ≥ 2.4 V at –3 mA, VOL ≤ 0.55 V at 64 mA) ensure robust interoperability with legacy 5 V logic families.

Internal architecture supports simultaneous high-impedance state entry/exit across all eight outputs via OE assertion, with specified tPZL (3.2–10 ns) and tPHZ (1.2–6.3 ns) timing to minimize bus contention during state transitions. Output structure is designed for direct connection to terminated transmission lines or memory address buses requiring symmetrical drive strength and fast edge rates.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	4.5 V to 5.5 V - Ensures stable operation across standard TTL power rail tolerances.
Output Drive (IOL)	64 mA - Supports heavy capacitive loads and multiple TTL inputs on shared bus lines.
Propagation Delay (tPHL)	1.2–5.7 ns - Enables high-speed address/data buffering in 20–30 MHz system clocks.
3-State Leakage (IOZL)	–50 µA - Minimizes standby current and prevents unintended bus loading when disabled.
Operating Temperature	0°C to 70°C - Qualified for commercial and industrial embedded control environments.
Input Thresholds	VIL = 0.8 V, VIH = 2.0 V - Guarantees reliable logic recognition across voltage and noise margins.
Package	20-pin SOP (NS) - Surface-mount footprint compatible with automated assembly and space-constrained PCB layouts.

Pinout & Package

The SN74F240NSR is housed in a 20-pin small-outline package (SOP-20, package code NS), 7.5 mm wide, with 1.27 mm pitch and 2.65 mm max height. Pin 1 is located at the top-left corner (Q1 quadrant per tape orientation), with gull-wing leads suitable for reflow soldering.

Pin/Terminal	Circuit Role	Design Meaning
1OE	Section 1 Output Enable (active-low)	Controls Y1–Y4 outputs; low = enabled, high = high-Z.
1A1–1A4	Section 1 Data Inputs	Noninverting inputs driving outputs Y1–Y4 respectively.
2OE	Section 2 Output Enable (active-low)	Controls Y5–Y8 outputs; independent of 1OE for flexible bus partitioning.
2A1–2A4	Section 2 Data Inputs	Noninverting inputs driving outputs Y5–Y8 respectively.
1Y1–1Y4, 2Y1–2Y4	Buffer Outputs	3-state outputs with TTL-compatible VOH/VOL and ±64 mA sink/source capability.
VCC (Pin 20)	Power Supply	5 V nominal supply; must be decoupled locally to suppress switching noise.
GND (Pin 10)	Ground Reference	Common return path for all I/O and internal logic; critical for noise immunity.

Key Features

Feature	Design Value
Dual independent 4-bit sections	Enables selective bus segmentation-e.g., isolate address vs. data paths using separate OE controls.
High-current 3-state outputs	64 mA sink capability allows direct drive of up to 20 standard TTL loads per output without external buffers.
Fast enable/disable timing	tPZL = 3.2–10 ns ensures minimal bus float time during state transitions, reducing contention risk.
TTL-compatible interface	Guaranteed VIH/VIL and VOH/VOL margins eliminate level-shifting needs in mixed 5 V logic systems.
SOP-20 surface-mount package	Reduces PCB area by >50% vs. PDIP while maintaining pin compatibility with legacy designs.

Applications

Memory Address Buffering	System Bus Isolation
Use Scenario: Driving 16-bit address bus between microprocessor and SRAM/ROM in embedded controllers. IC Role / Device Role / Timing Role: Noninverting buffer with independent OE control isolates memory subsystem during DMA cycles. Use Value: Prevents address bus contention and reduces setup/hold timing violations via sub-6 ns propagation delay and precise 3-state timing.	Use Scenario: Interfacing multiple peripheral devices (UART, SPI controller, ADC) to a shared data bus. IC Role / Device Role / Timing Role: Bidirectional bus driver enabling controlled access with OE-synchronized enable/disable sequencing. Use Value: Eliminates need for discrete pull-ups or bus-hold circuits due to low leakage (<50 µA) and strong drive (64 mA).
Clock Distribution	Legacy System Upgrade Interface
Use Scenario: Distributing CPU clock or strobe signals to multiple synchronous peripherals in industrial PLCs. IC Role / Device Role / Timing Role: Low-skew, noninverting fanout buffer with matched tPLH/tPHL ensuring phase-aligned edges. Use Value: Maintains <1 ns skew across all eight outputs, preserving timing integrity in multi-device synchronous timing domains.	Use Scenario: Integrating modern microcontrollers with legacy TTL-based logic boards (e.g., ISA bus expansion). IC Role / Device Role / Timing Role: Level- and protocol-transparent interface bridging 3.3 V MCU GPIOs to 5 V address/data buses. Use Value: Provides full 5 V TTL drive compliance without external level shifters, simplifying redesign of aging hardware platforms.

Memory Address Buffering

System Bus Isolation

Use Scenario: Driving 16-bit address bus between microprocessor and SRAM/ROM in embedded controllers.

IC Role / Device Role / Timing Role: Noninverting buffer with independent OE control isolates memory subsystem during DMA cycles.

Use Value: Prevents address bus contention and reduces setup/hold timing violations via sub-6 ns propagation delay and precise 3-state timing.

Use Scenario: Interfacing multiple peripheral devices (UART, SPI controller, ADC) to a shared data bus.

IC Role / Device Role / Timing Role: Bidirectional bus driver enabling controlled access with OE-synchronized enable/disable sequencing.

Use Value: Eliminates need for discrete pull-ups or bus-hold circuits due to low leakage (<50 µA) and strong drive (64 mA).

Clock Distribution

Legacy System Upgrade Interface

Use Scenario: Distributing CPU clock or strobe signals to multiple synchronous peripherals in industrial PLCs.

IC Role / Device Role / Timing Role: Low-skew, noninverting fanout buffer with matched tPLH/tPHL ensuring phase-aligned edges.

Use Value: Maintains <1 ns skew across all eight outputs, preserving timing integrity in multi-device synchronous timing domains.

Use Scenario: Integrating modern microcontrollers with legacy TTL-based logic boards (e.g., ISA bus expansion).

IC Role / Device Role / Timing Role: Level- and protocol-transparent interface bridging 3.3 V MCU GPIOs to 5 V address/data buses.

Use Value: Provides full 5 V TTL drive compliance without external level shifters, simplifying redesign of aging hardware platforms.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-state buffer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS240N	Lower drive (IOL = 24 mA), slower speed (tPHL ≈ 15 ns), PDIP-only packaging.	Acceptable only in low-speed, low-fanout legacy systems where power and timing margins permit.	Choose only if backward compatibility with LS-family boards is mandatory and performance requirements are relaxed.
SN74ACT240DBR	CMOS technology, 5 V tolerant, higher speed (tPHL ≈ 6.5 ns), lower ICC (2 µA), but requires 4.5–5.5 V supply.	Better for mixed-voltage systems needing low static power and improved noise immunity.	Select when upgrading from F-series for lower power or tighter timing budgets-verify VIL/VIH compatibility with driving source.

Compared with SN74LS240N, SN74F240NSR delivers 2.7× higher output current and ~3× faster propagation, making it suitable for denser, higher-speed bus architectures; versus SN74ACT240DBR, it offers superior noise margin and proven reliability in long-lifecycle industrial deployments, though at higher quiescent current.

Availability

SN74F240NSR is available at Aetrix Electronics and suitable for memory address buffering, system bus isolation, clock distribution, and legacy interface applications requiring stable component supply and long-term industrial availability.

Supply support for SN74F240NSR 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 specializing in analog, embedded processing, and logic solutions with over 50 years of industrial-grade product development.

The SN74F240NSR belongs to TI's 74F family of fast TTL logic devices, engineered for high-speed, high-drive bus interfacing in mission-critical computing and control systems.

FAQ

What is the maximum output sink current specification for SN74F240NSR?

The SN74F240NSR is rated for 64 mA low-level output current (IOL) under recommended operating conditions (VCC = 4.5 V, TA = 0°C to 70°C). This value is confirmed in the "electrical characteristics" table of the official SDFS061A datasheet and enables direct drive of up to 20 standard TTL inputs per output. Exceeding this rating risks thermal degradation or latch-up.

Does SN74F240NSR support true bidirectional data flow?

No, SN74F240NSR is a unidirectional noninverting buffer: data flows only from A inputs to Y outputs. It does not implement internal direction control or bus transceiver logic. For bidirectional operation, TI recommends the SN74F245 or SN74ACT245. The SN74F240NSR's 3-state outputs allow it to share a bus line, but external control logic must manage direction separately.

What is the pin 1 marking and orientation for SN74F240NSR in tape-and-reel packaging?

Per TI's PACKAGE MATERIALS INFORMATION (10-Aug-2026), SN74F240NSR uses Q1 quadrant orientation in tape: pin 1 is located in the upper-left corner of the cavity when the reel feeds with sprocket holes on the left. The device marking on the package reads "74F240", and the SOP-20 (NS) package has a 1.27 mm lead pitch with gull-wing terminations.

Can SN74F240NSR operate reliably at 4.5 V supply voltage?

Yes, SN74F240NSR is fully characterized for operation from 4.5 V to 5.5 V per its recommended operating conditions. At VCC = 4.5 V, it maintains guaranteed VOH ≥ 2.0 V (at –12 mA), VOL ≤ 0.55 V (at 64 mA), and tPHL ≤ 5.7 ns-meeting all TTL interface requirements. Operation below 4.5 V is outside specification and may result in marginal timing or noise immunity.

Is SN74F240NSR RoHS compliant and lead-free?

Yes, SN74F240NSR is RoHS compliant with lead-free terminal finish (NiPdAu/NiPdAu over copper leadframe, marked as "NIPDAU" in TI's packaging addendum). It carries MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH) and is qualified per JEDEC J-STD-020. The "Yes" RoHS status is explicitly listed for orderable part number SN74F240NSR in TI's official Package Option Addendum (15-Jul-2026).

SN74F240NSR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74F

Package/Case:: 20-SOIC (0.209", 5.30mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Logic Type:: Buffer, Inverting

Number of Elements:: 2

Number of Bits per Element:: 4

Input Type:: -

Output Type:: 3-State

Current - Output High, Low:: 15mA, 64mA

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SO

SN74F240NSR FAQ

1.How can I place an order for SN74F240NSR through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74F240NSR 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 SN74F240NSR reliable?

The price and inventory of SN74F240NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74F240NSR is usually 5 days.

3.What payment methods are accepted for SN74F240NSR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74F240NSR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74F240NSR?

SN74F240NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74F240NSR 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 SN74F240NSR?

For technical support, including SN74F240NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74F240NSR requirements.

6.How does Aetrix verify that SN74F240NSR is sourced from the original manufacturer or authorized distributors?

All SN74F240NSR 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 SN74F240NSR meets industry standards.

7.What is the process for return or replacement of SN74F240NSR?

All SN74F240NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74F240NSR, 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 SN74F240NSR part is unused and in its original packaging.

Return procedure for SN74F240NSR:

1.Submit a request within 90 days.

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

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