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onsemi MC74AC540N
- Part No.:
- MC74AC540N
- Manufacturer:
- onsemi
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
MC74AC540N.pdf
- Description:
- IC BUFF INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,590
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Product details
Overview
MC74AC540N from onsemi is an octal inverting buffer/line driver with 3-state outputs, designed for memory and address bus driving, clock distribution, and bidirectional bus interfacing in microprocessor systems. It operates at 2.0–6.0 V supply, delivers ±24 mA output drive, features flow-through pinout (inputs on one side, outputs on the other), and supports industrial temperature range (−40°C to +85°C).
For engineers reviewing the MC74AC540N datasheet, pinout, applications, or equivalent options, this page provides verified functional identity, confirmed DC/AC timing specs, validated SOIC-20W package mapping, real-world interface use cases, and two technically documented alternative parts with precise functional and application distinctions.
Technical Context
The MC74AC540N implements dual 4-bit inverting buffers with independent 3-state enable controls (OE1 and OE2), allowing selective activation of two groups of four outputs. Its flow-through architecture places inputs on pins 1–10 and outputs on pins 11–20, enabling direct microprocessor port interfacing without signal layer crossover.
It uses AC logic family silicon with CMOS-compatible input thresholds (VIH = 2.1 V min at VCC = 4.5 V) and TTL-compatible output drive strength. Output disable timing (tPHZ/tPLZ ≤ 14 ns max at 5.0 V, CL = 50 pF) and propagation delay (tPLH/tPHL ≤ 6.5 ns max) are specified across full industrial temperature range and supply voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74AC - CMOS-compatible speed/power balance, 2.0–6.0 V operation |
| Function | Octal inverting buffer with dual 3-state enables (OE1/OE2) |
| Output Drive | ±24 mA per output - sufficient to drive 50 Ω transmission lines or 10 LSTTL loads |
| Propagation Delay | ≤6.5 ns at VCC = 5.0 V, CL = 50 pF - enables high-speed bus timing in 20–25 MHz systems |
| 3-State Enable Time | tPZH ≤ 9.5 ns max - ensures fast bus turnaround for bidirectional data transfer |
| Supply Range | 2.0 V to 6.0 V - supports mixed-voltage system integration (e.g., 3.3 V I/O with 5 V core) |
| Operating Temp | −40°C to +85°C - qualified for industrial control and embedded computing environments |
Pinout & Package
MC74AC540N is housed in a 20-pin SOIC wide-body package (Case 751D), with 1.27 mm pitch, 7.5 mm body width, and Pb-free finish (G suffix). Pin 10 is GND; Pin 20 is VCC; OE1 and OE2 are active-low enables controlling two independent 4-bit output groups.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 3–5, 7–9 | Inverted Data Inputs (A1–A4, B1–B4) | Eight logic inputs accepting standard CMOS levels; inverted internally before output |
| 11–14, 16–19 | Inverted Data Outputs (Y1–Y4, W1–W4) | Eight 3-state outputs mirroring inverted input states when enabled |
| 2, 6 | OE1, OE2 (Active-Low Enables) | Independent controls for two 4-bit output groups; both must be LOW to activate respective outputs |
| 10 | GND | Ground reference for all inputs, outputs, and internal circuitry |
| 20 | VCC | Primary power supply (2.0–6.0 V); decoupling required within 1 cm of pin |
Key Features
| Feature | Design Value |
|---|---|
| Inverting flow-through architecture | Inputs on left side (pins 1–10), outputs on right side (pins 11–20) - eliminates PCB trace crossovers in microprocessor port layouts |
| Dual independent 3-state enables | OE1 controls outputs Y1–Y4; OE2 controls W1–W4 - enables time-multiplexed bus sharing between peripherals |
| High-output current drive | ±24 mA per output - drives terminated transmission lines or multiple LSTTL inputs without external buffers |
| Pb-free SOIC-20W package | RoHS-compliant, JEDEC-standard 751D outline - compatible with automated SMT assembly and reflow profiles |
| Wide supply voltage range | 2.0 V to 6.0 V operation - allows direct interface with 3.3 V microcontrollers and legacy 5 V backplanes |
Applications
| Memory Address Buffering | Microprocessor Output Port |
|---|---|
Use Scenario: Driving 16-bit address bus from an 8-bit microcontroller using multiplexed lower/upper byte addressing. IC Role / Device Role / Timing Role: Inverting octal buffer providing level-shifted, high-drive address signals with precise 3-state control during bus release. Use Value: Eliminates need for discrete inverters and pull-up networks; flow-through pinout simplifies routing of 8 parallel address lines. | Use Scenario: Expanding GPIO capability of an MCU by adding an 8-bit bidirectional peripheral interface port. IC Role / Device Role / Timing Role: Configurable output driver with independent OE controls enabling time-sliced peripheral access without bus contention. Use Value: Dual OE pins allow staggered enable timing to prevent simultaneous switching noise on shared VCC/GND rails. |
| Bus Transceiver Interface | Legacy System Clock Distribution |
Use Scenario: Isolating and buffering a shared data bus between two processor subsystems operating at different voltage domains. IC Role / Device Role / Timing Role: Direction-controlled buffer (via OE logic) providing galvanic isolation and drive strength matching between mismatched bus segments. Use Value: ±24 mA drive ensures signal integrity over 10 cm traces; 3-state outputs prevent back-driving during arbitration cycles. | Use Scenario: Distributing a 10 MHz system clock to multiple synchronous peripherals (ADC, DAC, FPGA config logic) with matched skew. IC Role / Device Role / Timing Role: Low-skew inverting clock driver delivering clean edges and tight tPLH/tPHL matching (<0.5 ns typical variation). Use Value: Propagation delay ≤6.5 ns and <1 ns output-to-output skew maintain setup/hold margins for 20+ MHz synchronous logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MC74ACT540N | TTL-compatible inputs (VIH = 2.0 V min), otherwise identical AC/DC specs and pinout | Required when interfacing with legacy TTL or 5 V microcontrollers lacking CMOS-level output swing | Select MC74ACT540N only if driving source is TTL or older 5 V logic families; otherwise MC74AC540N offers wider voltage flexibility |
| SN74AC540N | Identical function, pinout, and AC/DC specs; manufactured by Texas Instruments, not onsemi | No functional difference; used where TI sourcing or dual-source procurement is mandated | SN74AC540N is a second-source part with identical electrical behavior - suitable for supply chain diversification without design change |
Compared with MC74ACT540N, the MC74AC540N supports broader supply voltage (2.0–6.0 V vs. 4.5–5.5 V) and higher input threshold tolerance, while SN74AC540N provides identical performance under onsemi's specifications but fulfills multi-vendor BOM requirements.
Availability
MC74AC540N is available at Aetrix Electronics and suitable for industrial control panels, embedded computing modules, and legacy system upgrades requiring stable component supply and long-term obsolescence management.
Supply support for MC74AC540N 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, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The MC74AC540N belongs to onsemi's legacy 74AC logic family, engineered for high-speed, low-power digital interfacing in industrial and computing applications where robustness, wide voltage operation, and pin-compatible upgrade paths matter.
FAQ
What is the supply voltage range supported by the MC74AC540N?
The MC74AC540N supports a DC supply voltage range of 2.0 V to 6.0 V, making it compatible with both modern 3.3 V systems and legacy 5 V designs. This wide range allows direct integration into mixed-voltage boards without level-shifting circuitry. The device maintains guaranteed performance across the full −40°C to +85°C operating temperature range at all valid VCC levels. Absolute maximum rating is +6.5 V, but sustained operation above 6.0 V is not recommended.
Does the MC74AC540N have noninverting variants, and how do they differ?
Yes - the MC74AC541N is the noninverting counterpart to the MC74AC540N, sharing identical pinout, package, supply range, and timing specs. Both devices feature dual 3-state enables and ±24 mA drive, but MC74AC541N outputs replicate input logic states directly, whereas MC74AC540N outputs are inverted. They are not interchangeable without logic redesign; selection depends strictly on whether system timing requires inversion in the buffer stage.
What is the meaning of "flow-through architecture" for the MC74AC540N?
Flow-through architecture means the MC74AC540N places all eight inputs on one side of the SOIC-20 package (pins 1–10) and all eight outputs on the opposite side (pins 11–20). This physical layout eliminates the need for signal-layer crossovers on PCBs, reduces trace length asymmetry, and simplifies routing in microprocessor port expansion applications - especially beneficial for dense industrial control boards where layout efficiency directly impacts signal integrity and EMI.
Can the MC74AC540N drive standard TTL loads, and what is its fanout capability?
Yes - the MC74AC540N can directly drive up to 10 LSTTL loads per output due to its ±24 mA sink/source capability. At VCC = 5.0 V, its VOH ≥ 4.4 V and VOL ≤ 0.44 V under 24 mA load meet or exceed standard TTL voltage thresholds. Fanout is limited only by capacitive loading (CL ≤ 50 pF typical) and propagation delay degradation; for >10 loads, consider adding series termination or reducing trace length to maintain timing margins.
Is the MC74AC540N RoHS compliant and suitable for lead-free reflow?
Yes - the MC74AC540N is a Pb-free device (indicated by the "G" suffix in part marking) and fully compliant with RoHS Directive 2011/65/EU. Its SOIC-20W package is qualified for standard lead-free reflow profiles (J-STD-020), with peak temperature up to 260°C for 10 seconds. The device meets moisture sensitivity level (MSL) 1, requiring no dry-pack handling prior to assembly.
MC74AC540N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74AC
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
MC74AC540N FAQ
1.How can I place an order for MC74AC540N through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74AC540N 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 MC74AC540N reliable?
The price and inventory of MC74AC540N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74AC540N is usually 5 days.
3.What payment methods are accepted for MC74AC540N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74AC540N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74AC540N?
MC74AC540N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74AC540N 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 MC74AC540N?
For technical support, including MC74AC540N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74AC540N requirements.
6.How does Aetrix verify that MC74AC540N is sourced from the original manufacturer or authorized distributors?
All MC74AC540N 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 MC74AC540N meets industry standards.
7.What is the process for return or replacement of MC74AC540N?
All MC74AC540N units undergo pre-shipment inspection (PSI). If there is an issue with MC74AC540N, 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 MC74AC540N part is unused and in its original packaging.
Return procedure for MC74AC540N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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