onsemi 74AC540MTCX

Overview

74AC540MTCX from onsemi is an octal inverting buffer/line driver with 3-state outputs, designed for memory address driving, clock distribution, and bus-oriented transmitter/receiver applications. It operates from 2.0 V to 6.0 V, delivers ±24 mA output drive, features flow-through pinout (inputs and outputs on opposite sides), and supports industrial temperature range (−40°C to +85°C).

For engineers reviewing the 74AC540MTCX datasheet, pinout, applications, or equivalent options, key selection criteria include 3-state control logic (dual OE inputs), high-speed propagation delays (≤8.0 ns at 5 V), low ICC/IOZ leakage, Pb-free SOIC-20W packaging, and compatibility with TTL and CMOS logic families.

Technical Context

The 74AC540MTCX implements eight independent inverting buffers, each with separate 3-state enable controlled by two active-low OE inputs (OE1 and OE2). Its flow-through architecture places all eight inputs on one side and all eight outputs on the opposite side of the SOIC-20W package, optimizing PCB layout for microprocessor I/O port interfacing.

It uses advanced AC CMOS technology to achieve rail-to-rail output swing, guaranteed VOH ≥ 4.4 V and VOL ≤ 0.44 V at VCC = 4.5 V with 24 mA load, and supports fast edge rates (≥125 mV/ns) while maintaining low dynamic current and ESD robustness per JEDEC standards.

Key Specifications

Pinout & Package

74AC540MTCX is housed in a Pb-free SOIC-20W package (case 751BJ), 7.5 mm × 12.8 mm body, 1.27 mm pitch, 300-mil width. Pin 1 marked with notch or bevel; pinout follows JEDEC MS-013 standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal inverting buffer with 3-state applications.

Compared with 74AC540SCX and SN74AC540N, the 74AC540MTCX offers the narrowest SOIC-20W package for space-constrained boards, lowest ICC/IOZ for low-power systems, and tightest propagation delay matching - making it optimal for industrial microcontroller peripherals and high-density memory interfaces.

Availability

74AC540MTCX is available at Aetrix Electronics and suitable for memory address buffering, microprocessor I/O expansion, and industrial bus interface applications requiring stable component supply, RoHS compliance, and long-term industrial temperature support.

Supply support for 74AC540MTCX 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The 74AC540MTCX belongs to onsemi's legacy AC logic family - engineered for high-speed, low-power, TTL/CMOS-compatible digital interfacing in industrial control, instrumentation, and embedded computing systems.

FAQ

What logic family does the 74AC540MTCX belong to, and how does it differ from 74HC or 74LS variants?

The 74AC540MTCX belongs to the Advanced CMOS (AC) logic family. It differs from 74HC by offering higher speed (≤6.5 ns vs. ≤15 ns typical), lower ICC (≤80 µA vs. ≤40 µA), and stronger output drive (±24 mA vs. ±8 mA). Versus 74LS, it provides CMOS input thresholds, rail-to-rail outputs, and no input current loading - eliminating base-current design constraints of bipolar TTL.

How are the two output enable (OE) inputs used in the 74AC540MTCX?

The 74AC540MTCX uses two active-low OE inputs (pins 9 and 10) that operate in AND logic: both must be LOW for outputs Y1–Y8 to drive their inverted inputs; if either OE is HIGH, all outputs enter high-impedance state. This dual-OE structure allows flexible bus arbitration - e.g., one OE tied to CPU write strobe, the other to peripheral select, enabling precise timing control of data flow.

Does the 74AC540MTCX support mixed-voltage operation, such as interfacing 3.3 V microcontrollers with 5 V peripherals?

Yes, the 74AC540MTCX supports mixed-voltage operation across its full 2.0 V to 6.0 V VCC range. At VCC = 3.3 V, VIH is guaranteed ≥2.1 V and VIL ≤0.9 V - compatible with 3.3 V logic; at VCC = 5.0 V, VOH ≥4.4 V and VOL ≤0.44 V - drives 5 V TTL loads. Input thresholds scale with VCC, ensuring robust level translation without external resistors.

What is the maximum capacitive load the 74AC540MTCX can drive while maintaining specified timing?

The 74AC540MTCX AC specifications (e.g., tPLH ≤6.5 ns) are characterized at CL = 50 pF. While it can drive heavier loads (up to ~100 pF), propagation delay increases linearly - e.g., at CL = 100 pF, tPLH rises to ~10–12 ns. For reliable timing at 20+ MHz, keep trace + load capacitance ≤50 pF and use series termination or local decoupling near the driver.

Is the 74AC540MTCX pin-compatible with older 74F or 74ALS versions?

No, the 74AC540MTCX is not pin-compatible with 74F540 or 74ALS540. Although all are octal inverting 3-state buffers, they differ in pin assignment: 74F/ALS540 place OE inputs on pins 1 and 19, while 74AC540MTCX uses pins 9 and 10. Substituting requires PCB redesign. Always verify pinout against the specific device marking and case outline (751BJ for 74AC540MTCX).