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

STMicroelectronics M74HC540B1R

Name: M74HC540B1R
Brand: STMicroelectronics
SKU: M74HC540B1R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M74HC540B1R

Manufacturer:: STMicroelectronics

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-DIP (0.300", 7.62mm)

Datasheet:: M74HC540B1R.pdf

Description:: IC BUFFER INVERT 6V 20DIP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

M74HC540B1R from STMicroelectronics is an octal inverting bus buffer with 3-state outputs, designed for bidirectional data bus interfacing in high-speed digital systems. It features 9 ns typical propagation delay at 6 V, ±6 mA output drive capability, and operates across 2–6 V supply range - enabling use in mixed-voltage 3.3 V/5 V logic translation and memory address/data buffering applications.

For engineers reviewing the M74HC540B1R datasheet, M74HC540B1R pinout, M74HC540B1R application, or M74HC540B1R equivalent, key selection considerations include its dual enable inputs (G1/G2), symmetrical output impedance, high noise immunity (28% VCC), and DIP-20 package compatibility with legacy 74-series layouts.

Technical Context

The M74HC540B1R implements eight independent inverting buffers, each with a 3-state output controlled by a two-input AND gate (G1 ∧ G2). When either G1 or G2 is high, all Y1–Y8 outputs enter high-impedance mode - supporting shared bus arbitration without external logic.

Designed using silicon C2MOS technology, it delivers balanced tPLH ≅ tPHL propagation delays and supports input rise/fall times up to 1000 ns at 2 V, ensuring robust timing margin in noisy industrial environments with operating temperature range from –55 °C to +125 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage Range	2 V to 6 V - enables interoperability between 3.3 V and 5 V logic domains without level shifters
Propagation Delay (tPD)	9 ns (typ.) at VCC = 6 V - supports >50 MHz bus operation in synchronous systems
Output Drive (IOH/IOL)	±6 mA (min.) - sufficient to drive 50 pF loads with <22 ns transition time at 6 V
Quiescent Current (ICC)	4 µA (max.) at TA = 25 °C - enables low-power standby in battery-backed systems
Noise Immunity	VNIH/VNIL = 28% VCC (min.) - rejects >1.2 V peak noise on 5 V buses
Operating Temperature	–55 °C to +125 °C - qualified for automotive under-hood and industrial control environments
Input Capacitance	5 pF - minimizes loading on upstream drivers in fan-out-critical designs

Pinout & Package

Package: Plastic DIP-20 (0.300" wide), 20-pin through-hole, JEDEC MS-001 compliant. Pin layout places inputs (A1–A8, G1, G2) on left side and outputs (Y1–Y8) on right side to simplify PCB routing.

Pin/Terminal	Circuit Role	Design Meaning
1, 19	G1, G2	Active-high 3-state enable inputs; both must be low for output assertion
2–9	A1–A8	Inverting data inputs; each drives corresponding Yn output
10	GND	Ground reference for all internal logic and I/O structures
11–18	Y1–Y8	Inverting 3-state outputs; high-impedance when G1 or G2 = high
20	VCC	Positive supply rail (2–6 V); decoupling capacitor required per best practice

Key Features

Feature	Design Value
Inverting 3-state bus buffer	Enables bidirectional data flow control on shared memory or peripheral buses
Dual AND-gated output enable	Prevents accidental bus contention during power-up or reset sequencing
Input protection circuits	ESD-rated to ±2 kV HBM; withstands transient voltage spikes on industrial I/O lines
Pin-compatible with 74LS540	Direct drop-in replacement for legacy TTL-based bus interface designs
Low input leakage	±0.1 µA max at 6 V - avoids signal degradation in high-impedance sensor interface nodes

Applications

Memory Address Buffering

Microcontroller Bus Expansion

Use Scenario: Driving 16-bit address bus from an 8-bit microcontroller with external RAM/ROM.

IC Role / Device Role / Timing Role: Inverting buffer with 3-state control synchronizes address latching and prevents bus contention during instruction fetch cycles.

Use Value: 9 ns propagation delay ensures setup/hold timing compliance with 12 MHz system clocks; ±6 mA drive sustains signal integrity over 10 cm PCB traces.

Use Scenario: Expanding GPIO count via parallel I/O port connected to MCU data bus.

IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling read/write access to external peripherals without direction-control pins.

Use Value: Dual enable inputs allow precise timing of data capture windows; 28% VCC noise margin suppresses coupling from adjacent motor drivers.

Industrial PLC Backplane Interface

Legacy System Logic Translation

Use Scenario: Isolating and buffering I/O module address/data lines in modular automation racks.

IC Role / Device Role / Timing Role: Level-shifting buffer between 5 V backplane and 3.3 V FPGA-based modules.

Use Value: 2–6 V supply range eliminates need for external regulators; –55 °C to +125 °C rating supports uncooled cabinet deployment.

Use Scenario: Replacing obsolete 74LS540 in repair of vintage test equipment with 5 V TTL logic.

IC Role / Device Role / Timing Role: Pin- and function-compatible CMOS upgrade reducing power consumption and heat generation.

Use Value: 4 µA quiescent current cuts standby power by >99% vs. original TTL part; identical DIP-20 footprint enables zero-rework board replacement.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74HC540N	Same logic function and pinout; TI version has slightly higher ICC (8 µA max) and lower VOL (0.05 V typ. at 6 mA)	Qualified to AEC-Q100 Grade 2; preferred for automotive infotainment head units	Select when requiring TI's extended qualification or tighter VOL spec in noise-sensitive analog-digital hybrid boards
74VHC540N	Faster tPD (5.5 ns typ. at 5 V); higher ICC (20 µA max); narrower VCC range (2–5.5 V)	Optimized for high-speed communication interfaces (e.g., ISA bus clones) where sub-10 ns timing is critical	Select when prioritizing speed over ultra-low standby current or 6 V operation

Compared with SN74HC540N and 74VHC540N, the M74HC540B1R offers the widest supply range (2–6 V), lowest quiescent current (4 µA), and broadest temperature coverage (–55 °C to +125 °C), making it optimal for industrial and legacy-replacement use cases demanding robustness and compatibility.

Availability

M74HC540B1R is available at Aetrix Electronics and suitable for memory address buffering, microcontroller bus expansion, industrial PLC backplane interface, and legacy system logic translation requiring stable component supply and long-term obsolescence mitigation.

Supply support for M74HC540B1R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in automotive, industrial, and power management ICs with strong heritage in high-reliability logic families.

The M74HC540B1R belongs to ST's high-speed CMOS (HCMOS) logic portfolio, engineered for drop-in replacement of legacy TTL in industrial control, instrumentation, and telecom infrastructure where low power, wide voltage range, and extended temperature operation are essential.

FAQ

What is the maximum clock frequency supported by M74HC540B1R in bus applications?

The M74HC540B1R does not operate on a clock; it is a combinatorial buffer. Its 9 ns typical propagation delay at 6 V supports reliable operation in systems with bus toggle rates up to ~55 MHz, assuming 50 pF load and proper PCB layout. AC timing is validated per CL = 50 pF test conditions in the datasheet.

Can M74HC540B1R drive a 100 pF capacitive load reliably?

Yes - though datasheet AC specs are measured at 50 pF, the ±6 mA output drive capability ensures <30 ns transition time into 100 pF at 6 V (calculated via t = 0.35 / f ≈ 20 ns for 17.5 MHz bandwidth). Layout practices such as short traces and local decoupling remain critical for signal integrity.

Is M74HC540B1R RoHS compliant and lead-free?

Yes - M74HC540B1R (DIP-20 package) is manufactured per RoHS Directive 2011/65/EU and is lead-free. The plastic DIP package uses matte tin lead finish, and STMicroelectronics confirms full compliance in its official product change notices dated 2006 onward.

How does the dual-enable (G1/G2) architecture improve system reliability?

The AND-gated enable (G1 ∧ G2) requires both signals to be low for output activation, preventing unintended bus driving during power sequencing or reset glitches. This eliminates race conditions common in single-enable buffers and simplifies control logic in multi-master systems like industrial fieldbus nodes.

M74HC540B1R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: 74HC

Package/Case:: 20-DIP (0.300", 7.62mm)

Packaging:: Tube

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:: 7.8mA, 7.8mA

Voltage - Supply:: 2V ~ 6V

Operating Temperature:: -55°C ~ 125°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 20-DIP

M74HC540B1R FAQ

1.How can I place an order for M74HC540B1R through Aetrix?

Please submit a Request for Quotation (RFQ) for M74HC540B1R 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 M74HC540B1R reliable?

The price and inventory of M74HC540B1R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M74HC540B1R is usually 5 days.

3.What payment methods are accepted for M74HC540B1R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M74HC540B1R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M74HC540B1R?

M74HC540B1R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M74HC540B1R 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 M74HC540B1R?

For technical support, including M74HC540B1R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M74HC540B1R requirements.

6.How does Aetrix verify that M74HC540B1R is sourced from the original manufacturer or authorized distributors?

All M74HC540B1R 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 M74HC540B1R meets industry standards.

7.What is the process for return or replacement of M74HC540B1R?

All M74HC540B1R units undergo pre-shipment inspection (PSI). If there is an issue with M74HC540B1R, 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 M74HC540B1R part is unused and in its original packaging.

Return procedure for M74HC540B1R:

1.Submit a request within 90 days.

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

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