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

onsemi 74LCX540WMX

Name: 74LCX540WMX
Brand: onsemi
SKU: 74LCX540WMX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74LCX540WMX

Manufacturer:: onsemi

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-SOIC (0.295", 7.50mm Width)

Datasheet:: 74LCX540WMX.pdf

Description:: IC BUFFER INVERT 3.6V 20SOIC

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Inventory:19,000

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Product details

Overview

74LCX540WMX from ON Semiconductor (formerly Fairchild) is a low-voltage octal buffer/line driver with 5V-tolerant inputs and outputs, designed for memory/address bus driving, clock distribution, and bidirectional bus interfacing in mixed-voltage systems. It operates from 2.3V to 3.6V V_CC, delivers 6.5ns max propagation delay at 3.3V, supports live insertion/withdrawal, and features power-down high-impedance I/Os.

For engineers reviewing the 74LCX540WMX datasheet, pinout, applications, or equivalent options, key selection criteria include 5V tolerance on all I/Os, flow-through pinout for PCB layout optimization, 3-STATE dual enable control (OE1/OE2), and compatibility with 2.5V/3.3V logic domains interfacing legacy 5V subsystems.

Technical Context

The 74LCX540WMX implements an octal non-inverting 3-STATE buffer with dual independent output-enable inputs (OE1, OE2), enabling selective activation of two groups of four outputs. Its advanced CMOS process ensures high-speed operation while maintaining low ICC (≤10µA quiescent current) and robust noise immunity.

It supports true 5V-tolerant I/Os across full operating temperature (–40°C to +85°C), with input voltage range up to 5.5V and output capability to drive ±24mA at 3.3V - critical for bridging 3.3V microcontrollers to 5V peripherals without level shifters.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	2.3V–3.6V - Enables direct use with 2.5V and 3.3V supply rails without regulation overhead.
Propagation Delay (t_PD)	6.5ns max at V_CC = 3.3V - Supports >100MHz bus timing margins in address/data path applications.
I/O Voltage Tolerance	0V–5.5V - Allows safe connection to 5V signals without external clamping or translation circuitry.
Output Drive (I_OL/I_OH)	±24mA at V_CC = 3.3V - Sufficient to drive multiple TTL loads or terminated transmission lines.
Quiescent Current (I_CC)	10µA max - Minimizes standby power in battery-backed or energy-sensitive embedded systems.
3-STATE Enable/Disable Time	8.5ns max t_PZL/t_PHZ - Ensures clean bus arbitration with minimal contention window during direction switching.
Input Leakage (I_I)	±5.0µA max - Reduces signal integrity risk on high-impedance buses or long trace runs.

Pinout & Package

74LCX540WMX uses a 20-lead SOIC (JEDEC MS-013, 0.300" wide) package with gull-wing leads, optimized for automated assembly and thermal reliability in industrial PCB layouts.

Pin/Terminal	Circuit Role	Design Meaning
1, 19	OE1, OE2	Independent 3-STATE enable inputs - Active-Low control allows partitioned bus management (e.g., OE1 for lower nibble, OE2 for upper nibble).
2–9	I0–I7	Buffer inputs - Flow-through arrangement (inputs on left, outputs on right) simplifies layer routing and reduces crosstalk in dense bus designs.
11–18	O0–O7	Buffer outputs - Symmetric drive strength (±24mA) supports bidirectional data flow when paired with complementary devices.
10	GND	Ground reference - Dedicated ground pin minimizes ground bounce in high-speed switching.
20	V_CC	Power supply - Single 2.3V–3.6V rail eliminates need for auxiliary voltage regulators in mixed-signal systems.

Key Features

Feature	Design Value
5V-tolerant I/Os	Enables direct interface between 3.3V logic and 5V peripherals (e.g., legacy UARTs, displays, sensors) without external level translators.
Flow-through pinout	Inputs on left side (pins 2–9), outputs on right side (pins 11–18) - Reduces trace length and layer count in microprocessor address/data bus layouts.
Live insertion support	Power-down high-impedance I/Os prevent bus contention during hot-plug operations in modular backplane or docking station designs.
Low dynamic noise	Proprietary EMI reduction circuitry limits simultaneous switching noise (SSN), improving signal integrity in noise-sensitive analog/mixed-signal environments.
Latch-up immunity	Exceeds JEDEC 78 Class II requirements - Ensures robustness against transient overvoltage events in industrial control and automotive body electronics.

Applications

Memory Address Buffering	Microcontroller I/O Expansion
Use Scenario: Driving 16-bit address bus from a 3.3V ARM Cortex-M microcontroller to external SRAM or Flash memory operating at 5V. IC Role / Device Role / Timing Role: Non-inverting octal buffer providing level-shifted, low-skew address signals with 3-STATE isolation during memory read/write cycles. Use Value: Eliminates discrete level-shifter ICs and reduces BOM count by 3+ components while maintaining <6.5ns timing margin across all eight address lines.	Use Scenario: Expanding GPIO count of a 3.3V SoC to control eight 5V relay modules in industrial PLC I/O modules. IC Role / Device Role / Timing Role: Output port driver with dual OE control enabling grouped actuation (e.g., relays 0–3 via OE1, relays 4–7 via OE2). Use Value: Delivers ±24mA per output to directly drive relay coils, avoiding external transistor arrays and reducing PCB area by >40%.
Legacy Bus Interface	High-Density Clock Distribution
Use Scenario: Interfacing a modern 3.3V FPGA to a legacy ISA bus operating at 5V logic levels in test equipment retrofit designs. IC Role / Device Role / Timing Role: Bidirectional bus transceiver buffer (used unidirectionally) translating control/address signals with 5V-tolerant I/O protection. Use Value: Prevents damage from 5V bus transients while maintaining sub-7ns propagation delay - critical for meeting ISA timing setup/hold windows.	Use Scenario: Distributing a 3.3V system clock to eight synchronous peripherals (ADCs, DACs, FPGAs) requiring matched skew and low jitter. IC Role / Device Role / Timing Role: Low-skew clock buffer with output-to-output skew ≤1.0ns, minimizing clock domain misalignment. Use Value: Achieves <1ns inter-channel skew across all eight outputs - enabling precise time-of-flight measurements in multi-channel data acquisition systems.

Memory Address Buffering

Microcontroller I/O Expansion

Use Scenario: Driving 16-bit address bus from a 3.3V ARM Cortex-M microcontroller to external SRAM or Flash memory operating at 5V.

IC Role / Device Role / Timing Role: Non-inverting octal buffer providing level-shifted, low-skew address signals with 3-STATE isolation during memory read/write cycles.

Use Value: Eliminates discrete level-shifter ICs and reduces BOM count by 3+ components while maintaining <6.5ns timing margin across all eight address lines.

Use Scenario: Expanding GPIO count of a 3.3V SoC to control eight 5V relay modules in industrial PLC I/O modules.

IC Role / Device Role / Timing Role: Output port driver with dual OE control enabling grouped actuation (e.g., relays 0–3 via OE1, relays 4–7 via OE2).

Use Value: Delivers ±24mA per output to directly drive relay coils, avoiding external transistor arrays and reducing PCB area by >40%.

Legacy Bus Interface

High-Density Clock Distribution

Use Scenario: Interfacing a modern 3.3V FPGA to a legacy ISA bus operating at 5V logic levels in test equipment retrofit designs.

IC Role / Device Role / Timing Role: Bidirectional bus transceiver buffer (used unidirectionally) translating control/address signals with 5V-tolerant I/O protection.

Use Value: Prevents damage from 5V bus transients while maintaining sub-7ns propagation delay - critical for meeting ISA timing setup/hold windows.

Use Scenario: Distributing a 3.3V system clock to eight synchronous peripherals (ADCs, DACs, FPGAs) requiring matched skew and low jitter.

IC Role / Device Role / Timing Role: Low-skew clock buffer with output-to-output skew ≤1.0ns, minimizing clock domain misalignment.

Use Value: Achieves <1ns inter-channel skew across all eight outputs - enabling precise time-of-flight measurements in multi-channel data acquisition systems.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
74LVC541APW,118	Single OE input (vs. dual OE1/OE2); identical 5V-tolerant I/Os and 3.3V V_CC range.	Lacks independent nibble control - unsuitable for partial bus gating but simpler for full-bus enable scenarios.	Select when unified 3-STATE control suffices and board space favors TSSOP20 over SOIC20.
SN74LVCH16244ADGGR	16-bit (dual-octal), higher drive (±32mA), 1.65V–3.6V V_CC; no 5V tolerance - requires external clamping for 5V interfaces.	Not 5V-tolerant - cannot replace 74LCX540WMX in mixed-voltage systems without redesign.	Choose only for pure 3.3V/2.5V systems needing higher channel density and drive strength.

Compared with 74LVC541APW,118 and SN74LVCH16244ADGGR, the 74LCX540WMX uniquely combines dual-OE granularity, native 5V I/O tolerance, and SOIC20 manufacturability - making it the only drop-in solution for legacy bus bridging where partial enable control and voltage interoperability are mandatory.

Availability

74LCX540WMX is available at Aetrix Electronics and suitable for memory subsystems, microcontroller I/O expansion, legacy bus interfacing, and clock distribution requiring stable component supply across industrial, test & measurement, and embedded computing programs.

Supply support for 74LCX540WMX 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global leader in intelligent power and sensing solutions, delivering high-performance semiconductor components for automotive, industrial, cloud, and consumer applications.

The 74LCX family was engineered specifically for low-voltage, high-speed bus interface applications in mixed-signal systems - emphasizing 5V tolerance, flow-through layout efficiency, and robust ESD/latch-up performance.

FAQ

What is the maximum operating temperature range for the 74LCX540WMX?

The 74LCX540WMX is rated for free-air operating temperatures from –40°C to +85°C, validated across its full 2.3V–3.6V V_CC range. This specification ensures reliable operation in industrial control cabinets, outdoor instrumentation enclosures, and automotive under-hood environments where ambient thermal stress is present. All AC and DC parameters in the 74LCX540WMX datasheet are guaranteed within this range.

Does the 74LCX540WMX require external pull-up resistors on OE pins during power-up?

Yes - to guarantee high-impedance outputs during power-up or power-down sequences, OE1 and OE2 must be tied to V_CC via pull-up resistors. The minimum resistor value depends on the current-sourcing capability of the upstream driver; typical values range from 4.7kΩ to 10kΩ. This prevents bus contention in systems with asynchronous power sequencing, such as hot-swap backplanes or modular compute cards using the 74LCX540WMX.

Can the 74LCX540WMX safely interface with 5V logic while powered at 2.5V?

Yes - the 74LCX540WMX maintains full 5V tolerance on all inputs and outputs regardless of V_CC level (2.3V–3.6V). When powered at 2.5V, it accepts 0–5.5V input signals and drives outputs to valid HIGH/LOW levels compatible with 5V TTL thresholds. This enables direct connection to 5V peripherals without level shifters, preserving timing integrity and reducing component count in mixed-voltage designs using the 74LCX540WMX.

What is the recommended PCB land pattern for the 74LCX540WMX SOIC package?

The 74LCX540WMX SOIC20 (M20B) package requires the JEDEC MS-013 compliant land pattern: 12.60mm × 7.60mm body, 1.27mm lead pitch, and 0.65mm pad width. Fairchild specifies "SOIC127P1030X265-20L" as the standard footprint - ensuring adequate solder fillet formation, thermal relief, and mechanical stability during reflow. Using this exact pattern avoids tombstoning, insufficient wetting, or solder bridging in high-volume manufacturing of boards incorporating the 74LCX540WMX.

How does the 74LCX540WMX handle simultaneous switching noise (SSN)?

The 74LCX540WMX integrates proprietary noise/EMI reduction circuitry that staggers internal output switching edges and optimizes drive strength slew rates. Measured dynamic peak VOL (VOLP) is limited to 0.8V at 3.3V V_CC, and quiet-output valley VOL (VOLV) stays above –0.8V - significantly reducing ground bounce and supply rail collapse. This design allows the 74LCX540WMX to maintain signal integrity in high-density PCBs with tightly coupled power/ground planes, especially when multiple units drive shared buses.

74LCX540WMX Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: 74LCX

Package/Case:: 20-SOIC (0.295", 7.50mm Width)

Packaging:: Bulk

Product Status:: Active

Logic Type:: Buffer, Inverting

Number of Elements:: 1

Number of Bits per Element:: 8

Input Type:: -

Output Type:: 3-State

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

Voltage - Supply:: 2V ~ 3.6V

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SOIC

74LCX540WMX FAQ

1.How can I place an order for 74LCX540WMX through Aetrix?

Please submit a Request for Quotation (RFQ) for 74LCX540WMX 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 74LCX540WMX reliable?

The price and inventory of 74LCX540WMX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LCX540WMX is usually 5 days.

3.What payment methods are accepted for 74LCX540WMX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LCX540WMX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74LCX540WMX?

74LCX540WMX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74LCX540WMX 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 74LCX540WMX?

For technical support, including 74LCX540WMX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LCX540WMX requirements.

6.How does Aetrix verify that 74LCX540WMX is sourced from the original manufacturer or authorized distributors?

All 74LCX540WMX 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 74LCX540WMX meets industry standards.

7.What is the process for return or replacement of 74LCX540WMX?

All 74LCX540WMX units undergo pre-shipment inspection (PSI). If there is an issue with 74LCX540WMX, 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 74LCX540WMX part is unused and in its original packaging.

Return procedure for 74LCX540WMX:

1.Submit a request within 90 days.

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

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