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onsemi MC74LCX540MELG
- Part No.:
- MC74LCX540MELG
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
MC74LCX540MELG.pdf
- Description:
- IC BUFFER INVERT 3.6V SOEIAJ-20
- Quantity:
- Payment:
- Shipping:
Inventory:1,090
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Product details
Overview
MC74LCX540MELG from onsemi is a low-voltage CMOS octal inverting buffer with 3-state outputs, flow-through pinout, and 5 V-tolerant I/O. It operates from 2.3 V to 3.6 V, delivers ±24 mA output drive at 3.0–3.6 V, supports −40°C to +85°C operation, and features near-zero static ICC (10 µA) in all logic states. It is used for memory address driving and TTL-level bus transceiver applications.
For engineers reviewing the MC74LCX540MELG datasheet, pinout, applications, or equivalent options, key selection criteria include 5 V-tolerant I/O compatibility, 24 mA balanced sink/source capability, flow-through architecture for PCB routing efficiency, and IOFF protection for live insertion.
Technical Context
The MC74LCX540MELG implements dual independent 3-state enable controls (OE1, OE2), each disabling all eight outputs into high-impedance when HIGH. Its inverting logic function propagates D0–D7 to O0–O7 with tPLH/tPHL ≤ 7.5 ns at VCC = 3.0–3.6 V and CL = 50 pF.
It uses LVTTL/LVCMOS-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and guarantees 5.5 V absolute maximum input voltage. The IOFF specification ensures high-impedance outputs even when VCC = 0 V, enabling hot-swap capability without back-driving powered systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3 V to 3.6 V - Enables direct interface with 2.5 V/3.3 V logic domains without level shifters. |
| Input Voltage Tolerance | −0.5 V to +7.0 V - Allows safe connection to 5 V TTL sources without external clamping. |
| Output Drive | ±24 mA at VCC = 3.0–3.6 V - Sufficient to drive multiple LVTTL loads or terminate short stubs on shared buses. |
| Propagation Delay | tPLH/tPHL ≤ 7.5 ns - Supports >100 MHz bus toggle rates in point-to-point configurations. |
| Quiescent ICC | 10 µA max - Minimizes standby power in battery-backed or always-on subsystems. |
| IOFF Leakage | 10 µA max at VCC = 0 V - Prevents signal contention during hot-plug events or partial power-down. |
| ESD Rating | HBM >2000 V - Meets industrial-grade robustness requirements for board handling and field deployment. |
Pinout & Package
MC74LCX540MELG is packaged in a 20-pin SOIC wide-body (SOIC-20 WB, Case 751D), with 1.27 mm pitch, 12.8 mm × 7.5 mm body size, and Pb-free/Green compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Active-Low 3-state enables - Both must be LOW to activate outputs; HIGH places all O0–O7 in high-Z. |
| 2–9 | D0–D7 | Inverting data inputs - Each drives corresponding output with polarity inversion (Dn → On). |
| 11–18 | O0–O7 | Inverting 3-state outputs - Flow-through layout (D0–D7 left, O0–O7 right) simplifies PCB trace routing. |
| 10 | GND | Ground reference - Single ground pin serves all internal circuitry and output drivers. |
| 20 | VCC | Power supply - Single 2.3–3.6 V supply powers all logic and output stages. |
Key Features
| Feature | Design Value |
|---|---|
| 5 V-tolerant I/O | Supports mixed-voltage system integration where 5 V controllers drive 3.3 V peripherals without level translators. |
| Flow-through pinout | Minimizes layer count and trace crossovers in dense bus layouts by aligning inputs and outputs on opposite sides. |
| IOFF protection | Guarantees high-impedance outputs during power-off or brown-out, preventing back-powering of upstream devices. |
| 24 mA balanced drive | Enables reliable signal integrity across unterminated or lightly loaded 50 Ω transmission lines in compact embedded modules. |
| Latchup immunity | Exceeds 500 mA - Ensures robust operation in noisy industrial environments with transient coupling or EFT exposure. |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
Use Scenario: Driving address lines from a 3.3 V microcontroller to multiple SRAM or Flash ICs sharing a common address bus. IC Role / Device Role / Timing Role: Inverting octal buffer providing level-shifted, noise-immune address propagation with 3-state control for bus arbitration. Use Value: Eliminates need for discrete level shifters while maintaining <7.5 ns propagation delay and supporting 5 V-tolerant address decoding logic. | Use Scenario: Isolating and buffering bidirectional data/control signals between a 2.5 V FPGA I/O bank and legacy 5 V industrial PLC modules. IC Role / Device Role / Timing Role: Unidirectional inverting buffer with 3-state enable, used per signal direction to prevent contention on shared control lines. Use Value: Enables safe 5 V ↔ 3.3 V interfacing with ±24 mA drive strength and IOFF protection during FPGA reconfiguration. |
| Hot-Swappable Backplane Interface | Low-Power Embedded Control Bus |
Use Scenario: Buffering configuration signals (e.g., reset, chip select) between a powered backplane and removable daughter cards. IC Role / Device Role / Timing Role: 3-state inverting buffer with IOFF, allowing card insertion/removal while main system remains operational. Use Value: Prevents bus contention and back-driving during live insertion via guaranteed high-Z state at VCC = 0 V. | Use Scenario: Driving LED indicators, relay drivers, or sensor interface lines in a battery-powered IoT node operating at 3.0 V. IC Role / Device Role / Timing Role: Low-quiescent-current inverting buffer delivering precise logic inversion with minimal standby power draw. Use Value: Achieves 10 µA ICC in all states, extending battery life without sacrificing drive strength or noise margin. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC240APWR | Same 2.7–3.6 V VCC range, but only 5 V-tolerant inputs (not outputs); tPLH/tPHL = 6.5 ns typical. | Lacks 5 V-tolerant outputs - requires external clamping if driving 5 V loads. | Select when output voltage swing is constrained to VCC and system-level clamping is already present. |
| 74LCX540MTCX | Identical electrical specs and pinout; differs only in TSSOP-20 package (Case 948E) and moisture sensitivity level (MSL 1 vs MSL 3). | No functional difference - suitable for space-constrained designs requiring smaller footprint. | Select when board area is critical and reflow profile accommodates MSL 3 handling. |
Compared with SN74LVC240APWR and 74LCX540MTCX, the MC74LCX540MELG uniquely combines full 5 V-tolerant I/O with SOIC-20 WB mechanical robustness and MSL 1 rating, making it optimal for industrial backplanes and mixed-voltage control buses requiring zero-layout change upgrades from legacy 74LS540 designs.
Availability
MC74LCX540MELG is available at Aetrix Electronics and suitable for memory address buffering, industrial bus transceivers, and hot-swappable backplane interfaces requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for MC74LCX540MELG 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 focused on energy-efficient electronics, serving automotive, industrial, cloud, and IoT markets with discrete, analog, and logic solutions.
The MC74LCX540MELG belongs to the LCX low-voltage CMOS logic family, designed specifically for high-speed, low-power interfacing between mixed-voltage digital subsystems in industrial control and embedded computing.
FAQ
What is the maximum input voltage rating for MC74LCX540MELG?
The MC74LCX540MELG supports DC input voltages from −0.5 V to +7.0 V, with a specified VI of up to 5.5 V for safe interfacing with 5 V TTL logic. This 5 V tolerance applies to both inputs and outputs, enabling direct connection to legacy 5 V systems without external protection components. The absolute maximum rating ensures robustness against transient overvoltage conditions within defined limits.
Does MC74LCX540MELG support hot-swap operation?
Yes, the MC74LCX540MELG supports hot-swap operation due to its IOFF specification, which guarantees high-impedance outputs when VCC = 0 V. This prevents back-driving of powered circuits during card insertion or removal. The device maintains isolation even when unpowered, making it suitable for modular backplane architectures and field-replaceable units where live insertion is required.
What is the output drive capability of MC74LCX540MELG at 3.3 V supply?
At VCC = 3.0 V to 3.6 V, the MC74LCX540MELG provides ±24 mA output drive - 24 mA sink current (IOL) and −24 mA source current (IOH). This balanced capability allows reliable driving of multiple LVTTL loads or termination of short PCB traces. Performance is validated per AC test conditions with CL = 50 pF and RL = 500 Ω, ensuring signal integrity in real-world bus environments.
Is MC74LCX540MELG pin-compatible with standard 74-series octal buffers?
No, the MC74LCX540MELG is not pin-compatible with standard 74LS540 or 74HC540 due to its flow-through pinout (inputs on one side, outputs on the other) and dual OE pins (pins 1 and 19). Standard 74-series parts use interleaved or centralized enable layouts. PCB redesign is required to adopt MC74LCX540MELG, though its SOIC-20 WB footprint matches industry-standard 20-pin SOIC land patterns.
What is the quiescent supply current of MC74LCX540MELG in all logic states?
The MC74LCX540MELG exhibits near-zero static supply current: ICC ≤ 10 µA maximum across all three logic states (HIGH, LOW, and HIGH-Z) when VCC = 3.6 V and inputs are at VIH or VIL. This ultra-low quiescent current significantly reduces system-level power consumption in always-on or battery-operated applications, distinguishing it from older bipolar or higher-leakage CMOS logic families.
MC74LCX540MELG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LCX
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- SOEIAJ-20
MC74LCX540MELG FAQ
1.How can I place an order for MC74LCX540MELG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74LCX540MELG 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 MC74LCX540MELG reliable?
The price and inventory of MC74LCX540MELG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74LCX540MELG is usually 5 days.
3.What payment methods are accepted for MC74LCX540MELG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74LCX540MELG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74LCX540MELG?
MC74LCX540MELG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74LCX540MELG 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 MC74LCX540MELG?
For technical support, including MC74LCX540MELG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74LCX540MELG requirements.
6.How does Aetrix verify that MC74LCX540MELG is sourced from the original manufacturer or authorized distributors?
All MC74LCX540MELG 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 MC74LCX540MELG meets industry standards.
7.What is the process for return or replacement of MC74LCX540MELG?
All MC74LCX540MELG units undergo pre-shipment inspection (PSI). If there is an issue with MC74LCX540MELG, 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 MC74LCX540MELG part is unused and in its original packaging.
Return procedure for MC74LCX540MELG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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