STMicroelectronics 74ACT125MTR

Overview

74ACT125MTR from STMicroelectronics is a quad 3-state bus buffer IC designed for high-speed bidirectional data routing in TTL- and CMOS-compatible digital systems. It features 5 ns typical propagation delay at 5 V, ±24 mA symmetrical output drive, 4.5–5.5 V operating range, and 2 kV ESD immunity. Used in address/data bus isolation in industrial controllers and memory interface logic.

For engineers reviewing the 74ACT125MTR datasheet, 74ACT125MTR pinout, 74ACT125MTR application, or 74ACT125MTR equivalent, key selection criteria include 3-state enable timing (tPZL/tPHZ ≤10 ns), transmission-line driving capability (50 Ω matched), and latch-up immunity for robust operation in noisy embedded environments.

Technical Context

The 74ACT125 implements four independent non-inverting buffers, each with active-low 3-state control (G1–G4). Output enable/disable transitions are internally balanced to minimize bus contention during state changes.

It uses sub-micron C2MOS technology with double-layer metal wiring, enabling TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) while maintaining CMOS low power (ICC ≤ 4 µA at 25°C) and high noise immunity.

Key Specifications

Pinout & Package

74ACT125MTR is supplied in a 14-pin SOIC (Small Outline Integrated Circuit) package, 3.9 mm body width, with standard 1.27 mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT125DR, 74ACT125MTR offers identical timing and drive but distinct manufacturing traceability; versus 74LCX125MTCX, it maintains full 5 V TTL compatibility at the cost of higher supply voltage requirement-critical for mixed-voltage backplane integration.

Availability

74ACT125MTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, microcontroller address bus isolation, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74ACT125MTR 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, designing and manufacturing analog, digital, and mixed-signal ICs for industrial, automotive, and consumer applications.

The 74ACT series targets high-speed, low-power, TTL-compatible logic interfaces-specifically engineered for robust signal integrity in electrically noisy environments like factory automation and vehicle ECUs.

FAQ

What is the maximum recommended operating frequency for 74ACT125MTR?

The device has no specified maximum clock frequency, but its 5 ns typical propagation delay and 10 ns max enable/disable times support reliable operation up to 50 MHz in bus-enable-controlled applications. For continuous data streaming, signal integrity depends on trace length, termination, and load capacitance-not internal toggle rate.

Can 74ACT125MTR be used with 3.3 V logic inputs?

No-its input thresholds are TTL-defined (VIH ≥ 2.0 V min at VCC = 4.5 V), and 3.3 V logic may not guarantee valid high-level recognition across temperature and voltage tolerances. A level translator or 3.3 V–compatible ACT variant (e.g., 74LVT125) is required for mixed-voltage interfacing.

Is decoupling required for stable operation?

Yes-each 74ACT125MTR must have a 100 nF ceramic capacitor placed between VCC (pin 14) and GND (pin 7), located within 5 mm of the pins. This suppresses switching noise and prevents supply droop during simultaneous output transitions, especially critical at 24 mA drive levels.

Does 74ACT125MTR support hot-swap insertion?

It features improved latch-up immunity and 2 kV ESD protection, but lacks explicit hot-swap circuitry (e.g., slew-rate control or power sequencing). Use only in pre-powered slots or with external current-limiting and soft-start circuitry to avoid supply rail disturbance during insertion.