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

onsemi 74AC240SJ

Name: 74AC240SJ
Brand: onsemi
SKU: 74AC240SJ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74AC240SJ

Manufacturer:: onsemi

Category:: Buffers, Drivers, Receivers, Transceivers

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

Datasheet:: 74AC240SJ.pdf

Description:: IC BUFF INVERT 6V 20SOP

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Product details

Overview

74AC240SJ from onsemi is an octal inverting buffer/line driver with 3-state outputs, designed for memory address driving, bus-oriented data transmission, and clock distribution in high-density PCB layouts. It operates at 2.0–6.0 V supply, delivers ±24 mA output drive, and features TTL-compatible input thresholds only in ACT variants - the AC variant uses CMOS-compatible inputs. It supports industrial temperature range (−40°C to +85°C) and is Pb-free.

For engineers reviewing the 74AC240SJ datasheet, pinout, applications, or equivalent options, key selection criteria include its dual 3-state enable architecture (OE1/OE2), propagation delays under 9 ns at 5 V, low ICC (≤40 µA), and SOIC-20W package compatibility with legacy 74-series footprint constraints.

Technical Context

The 74AC240SJ implements eight independent inverting buffers, each with separate 3-state control via two grouped enable inputs (OE1 controls O0–O3; OE2 controls O4–O7). Its CMOS-based AC logic family ensures rail-to-rail output swing and low static power consumption while maintaining noise immunity through defined VIH/VIL thresholds across 3.3 V, 4.5 V, and 5.5 V operation.

It is not TTL-compatible - unlike the 74ACT240 - and requires CMOS-level input signaling. Output disable timing (tPHZ/tPLZ) and enable timing (tPZH/tPZL) are asymmetric and voltage-dependent, with worst-case values of 11.5 ns at 3.3 V and 9.5 ns at 5.0 V under 50 pF load.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage Range	2.0 V to 6.0 V - supports mixed-voltage system interfacing and legacy 5 V designs without level shifters.
Output Drive Strength	±24 mA per output - sufficient to directly drive 50 Ω transmission lines or fan-out to ≥10 LS-TTL loads.
Propagation Delay (tPLH/tPHL)	Max 9.0 ns at 5.0 V, CL = 50 pF - enables reliable operation in 100+ MHz bus systems with setup/hold margin.
3-State Leakage (IOZ)	±2.5 µA max - ensures minimal bus contention current when outputs are disabled in shared-bus configurations.
Input Thresholds (VIH/VIL)	VIH = 2.1 V min @ 3.0 V VCC; VIL = 0.9 V max - provides robust noise margin (>0.8 V) in noisy industrial environments.
Quiescent Supply Current (ICC)	40 µA max @ 5.5 V - enables low-power standby modes in battery-backed or energy-sensitive applications.
Operating Temperature	−40°C to +85°C - qualified for industrial-grade embedded control, instrumentation, and communications equipment.

Pinout & Package

74AC240SJ is packaged in SOIC-20W (case 751BJ), a 20-pin wide-body surface-mount package with 1.27 mm pitch, 12.8 mm × 7.5 mm body size, and JEDEC MS-013 compliance. Pin 1 is marked by a beveled corner or dot.

Pin/Terminal	Circuit Role	Design Meaning
1, 19	OE1, OE2	Active-low 3-state enable inputs - OE1 controls outputs O0–O3; OE2 controls O4–O7; independent control allows partial bus gating.
2–9	I0–I7	Inverting data inputs - each drives corresponding output with polarity inversion; no internal pull-ups or pull-downs.
11–18	O0–O7	Inverting 3-state outputs - high-impedance state activated when respective OE is HIGH; capable of sourcing/sinking 24 mA.
10	GND	Ground reference - must be low-inductance connection to minimize switching noise coupling into logic thresholds.
20	VCC	Positive supply - bypassing with 0.1 µF ceramic capacitor near pin is required for stable high-speed operation.

Key Features

Feature	Design Value
Reduced ICC and IOZ	50% lower than standard 74AC devices - extends system-level power budget and reduces ground bounce in dense routing.
Dual independent 3-state enables	OE1 and OE2 separately gate two 4-bit output groups - enables time-multiplexed bus sharing without external logic.
High-output drive (±24 mA)	Eliminates need for external bus transceivers in medium-fanout applications like FPGA I/O expansion or microcontroller peripheral buses.
Pb-free SOIC-20W packaging	Complies with JEDEC J-STD-020B - supports lead-free reflow profiles and meets RoHS Directive 2011/65/EU requirements.
Wide VCC operating range	2.0–6.0 V operation - interoperable with 3.3 V microcontrollers, 5 V legacy peripherals, and mixed-supply backplanes.

Applications

Memory Address Buffering	Industrial Bus Transceiver
Use Scenario: Driving 16-bit address bus from microcontroller to SRAM or EPROM in programmable logic controllers. IC Role / Device Role / Timing Role: Inverting octal buffer with grouped 3-state control isolates address lines during DMA cycles and prevents bus contention. Use Value: ±24 mA drive ensures full logic swing across 15 cm PCB traces; tPLH < 9 ns guarantees setup timing margin for 25 MHz memory access.	Use Scenario: Bidirectional data buffering between two isolated 8-bit microcontroller subsystems sharing a common parallel bus. IC Role / Device Role / Timing Role: Dual-enable 3-state architecture allows direction control via OE1/OE2 sequencing - no external direction pin needed. Use Value: Independent OE control eliminates timing race conditions during bus handoff; low IOZ (<2.5 µA) prevents leakage-induced logic errors.
Legacy System Clock Distribution	Test Equipment Signal Conditioning
Use Scenario: Fan-out and level-shifting of a 5 MHz system clock to multiple synchronous peripherals in test fixtures. IC Role / Device Role / Timing Role: Inverting buffer with rail-to-rail CMOS output restores edge integrity degraded by capacitive loading on long clock traces. Use Value: Propagation delay matching (tPLH ≈ tPHL) minimizes duty cycle distortion; low ICC preserves clock tree power integrity.	Use Scenario: Isolating and conditioning digital stimulus signals from ATE pattern generators before applying to DUT inputs. IC Role / Device Role / Timing Role: 3-state outputs allow safe signal injection during DUT power-up/down sequences without back-driving test hardware. Use Value: High-impedance disable state protects sensitive ATE drivers; ±24 mA sink capability handles DUT input leakage currents up to 20 µA.

Memory Address Buffering

Industrial Bus Transceiver

Use Scenario: Driving 16-bit address bus from microcontroller to SRAM or EPROM in programmable logic controllers.

IC Role / Device Role / Timing Role: Inverting octal buffer with grouped 3-state control isolates address lines during DMA cycles and prevents bus contention.

Use Value: ±24 mA drive ensures full logic swing across 15 cm PCB traces; tPLH < 9 ns guarantees setup timing margin for 25 MHz memory access.

Use Scenario: Bidirectional data buffering between two isolated 8-bit microcontroller subsystems sharing a common parallel bus.

IC Role / Device Role / Timing Role: Dual-enable 3-state architecture allows direction control via OE1/OE2 sequencing - no external direction pin needed.

Use Value: Independent OE control eliminates timing race conditions during bus handoff; low IOZ (<2.5 µA) prevents leakage-induced logic errors.

Legacy System Clock Distribution

Test Equipment Signal Conditioning

Use Scenario: Fan-out and level-shifting of a 5 MHz system clock to multiple synchronous peripherals in test fixtures.

IC Role / Device Role / Timing Role: Inverting buffer with rail-to-rail CMOS output restores edge integrity degraded by capacitive loading on long clock traces.

Use Value: Propagation delay matching (tPLH ≈ tPHL) minimizes duty cycle distortion; low ICC preserves clock tree power integrity.

Use Scenario: Isolating and conditioning digital stimulus signals from ATE pattern generators before applying to DUT inputs.

IC Role / Device Role / Timing Role: 3-state outputs allow safe signal injection during DUT power-up/down sequences without back-driving test hardware.

Use Value: High-impedance disable state protects sensitive ATE drivers; ±24 mA sink capability handles DUT input leakage currents up to 20 µA.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal inverting buffer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
74AC240SCX	Same AC logic family, identical electrical specs, but in SOIC-20W tape-and-reel packaging (no suffix 'J' indicating tube delivery).	No functional difference - differs only in packaging format and reel quantity (1000 vs. tube); pinout and thermal profile identical.	Select 74AC240SCX for automated SMT assembly; retain 74AC240SJ for manual prototyping or low-volume repair where tube handling is preferred.
74ACT240SCX	TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V @ 5 V), otherwise identical AC output drive and timing.	Required when interfacing with legacy TTL or LSTTL logic families; unsuitable for pure CMOS systems due to higher input current.	Choose 74ACT240SCX only if driving from 74LS or 74F series; otherwise 74AC240SJ offers better noise margin and lower power in CMOS-native designs.

Compared with 74AC240SCX, the 74AC240SJ offers identical performance in a tube-packaged form factor optimized for engineering validation; versus 74ACT240SCX, it trades TTL input compatibility for superior noise immunity and lower ICC in CMOS-system contexts.

Availability

74AC240SJ is available at Aetrix Electronics and suitable for industrial control systems, test equipment interfaces, and legacy bus expansion requiring stable component supply, long-term lifecycle support, and Pb-free compliance.

Supply support for 74AC240SJ 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, logic, and sensor solutions for automotive, industrial, and cloud infrastructure markets.

The 74AC240SJ belongs to onsemi's legacy 74AC logic family - engineered for high-speed, low-power, pin-compatible upgrades to standard TTL/LS logic in industrial and communications equipment.

FAQ

What is the function of OE1 and OE2 on the 74AC240SJ?

The 74AC240SJ uses OE1 and OE2 as active-low 3-state enable inputs: OE1 controls outputs O0–O3, and OE2 controls O4–O7. When either enable is HIGH, its associated four outputs enter high-impedance state; when LOW, they actively drive inverted input signals. This grouping allows selective bus segmentation without external logic, making the 74AC240SJ ideal for partial-bus isolation in memory or peripheral interfaces.

Does the 74AC240SJ support 3.3 V operation?

Yes, the 74AC240SJ is fully specified for 3.3 V operation (VCC = 3.0–3.6 V), with guaranteed VIH = 2.1 V, VIL = 0.9 V, VOH = 2.9 V, and VOL = 0.1 V at −24 mA/24 mA loads. Propagation delay is 8.0 ns max at 3.3 V, CL = 50 pF. Its CMOS input structure ensures compatibility with 3.3 V microcontrollers and FPGAs without level translation.

Is the 74AC240SJ pin-compatible with the 74LS240?

No - while both are octal inverting buffers with 3-state outputs, the 74AC240SJ has different pin assignments: OE1/OE2 are on pins 1 and 19, whereas 74LS240 places both enables on pin 1. Additionally, the 74AC240SJ uses SOIC-20W (751BJ) packaging with 1.27 mm pitch, differing from the 74LS240's narrower SOIC-20 (751D) or PDIP-20 footprints. Direct replacement requires PCB layout revision.

What is the maximum capacitive load the 74AC240SJ can drive reliably?

The 74AC240SJ is characterized for CL = 50 pF in AC timing specifications, with propagation delays and transition times validated under that load. While it can drive heavier loads (e.g., >100 pF), timing margins degrade - tPLH/tPHL increase by ~0.5 ns per 10 pF beyond 50 pF. For reliable 25 MHz bus operation, total trace + load capacitance should remain ≤60 pF; above that, consider adding series termination or using a dedicated bus driver.

How does the 74AC240SJ differ from the 74ACT240 in practical design use?

The 74AC240SJ uses CMOS-compatible inputs (VIH ≈ 0.7×VCC), while the 74ACT240 uses TTL-compatible inputs (VIH = 2.0 V fixed). This makes the 74AC240SJ better suited for pure CMOS systems (e.g., 3.3 V FPGAs) with higher noise immunity, whereas the 74ACT240 is necessary for interfacing with older 74LS or 74F logic. Both share identical output drive, timing, and 3-state behavior - the input threshold difference is the sole critical selection factor.

74AC240SJ Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: 74AC

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

Packaging:: Tube

Product Status:: Obsolete

Logic Type:: Buffer, Inverting

Number of Elements:: 2

Number of Bits per Element:: 4

Input Type:: -

Output Type:: 3-State

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

Voltage - Supply:: 2V ~ 6V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SOP

74AC240SJ FAQ

1.How can I place an order for 74AC240SJ through Aetrix?

Please submit a Request for Quotation (RFQ) for 74AC240SJ 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 74AC240SJ reliable?

The price and inventory of 74AC240SJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC240SJ is usually 5 days.

3.What payment methods are accepted for 74AC240SJ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC240SJ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74AC240SJ?

74AC240SJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74AC240SJ 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 74AC240SJ?

For technical support, including 74AC240SJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC240SJ requirements.

6.How does Aetrix verify that 74AC240SJ is sourced from the original manufacturer or authorized distributors?

All 74AC240SJ 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 74AC240SJ meets industry standards.

7.What is the process for return or replacement of 74AC240SJ?

All 74AC240SJ units undergo pre-shipment inspection (PSI). If there is an issue with 74AC240SJ, 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 74AC240SJ part is unused and in its original packaging.

Return procedure for 74AC240SJ:

1.Submit a request within 90 days.

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

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