STMicroelectronics 74LCX125MTR

Overview

74LCX125MTR from STMicroelectronics is a low-voltage CMOS quad 3-state bus buffer with 5 V tolerant inputs/outputs, operating from 2.0 V to 3.6 V, delivering 5.2 ns max propagation delay at 3 V and ±24 mA symmetrical output drive. It serves as a level-translating bidirectional interface between 3.3 V logic domains and legacy 5 V systems in PCI-compliant data buses.

For engineers reviewing the 74LCX125MTR datasheet, 74LCX125MTR pinout, 74LCX125MTR application, or 74LCX125MTR equivalent, this device is selected for high-speed, low-power 3.3 V bus buffering where 5 V tolerance, precise timing matching (tPLH ≅ tPHL), and robust ESD immunity (2000 V HBM) are required in automotive and industrial control backplanes.

Technical Context

The 74LCX125MTR implements four independent non-inverting buffers, each controlled by a dedicated active-low 3-state enable input (G). Its C2MOS sub-micron process enables rail-to-rail 5 V tolerance while maintaining TTL-compatible thresholds at 3.3 V supply.

All outputs feature matched high- and low-side drive strength (|IOH| = IOL ≥ 24 mA at VCC = 3.0–3.6 V), ensuring balanced signal integrity in multi-drop bus environments. Input and output protection circuits guarantee latch-up immunity >500 mA per JESD17 and transient voltage resilience up to ±7 V absolute maximum ratings.

Key Specifications

Pinout & Package

74LCX125MTR is housed in a 14-pin SOIC (SO-14) package with standard 1.27 mm pitch, compliant with ECOPACK® environmental specifications. Pin 7 is GND and Pin 14 is VCC; no thermal pad or exposed die attach.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LVC125AD and SN74LVCH125APW, the 74LCX125MTR uniquely combines guaranteed 5 V tolerance on both inputs and outputs with symmetrical ±24 mA drive and <5.2 ns delay - making it optimal for legacy 5 V bus interfacing where output clamping cannot be assumed.

Availability

74LCX125MTR is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC backplanes, and embedded computer memory expansion requiring stable component supply across extended temperature ranges (−40 °C to +85 °C).

Supply support for 74LCX125MTR 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, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The 74LCX logic family was engineered specifically for low-voltage, high-speed 3.3 V system interfacing with backward compatibility to 5 V environments - targeting cost-sensitive, noise-resilient industrial and automotive control applications.

FAQ

Is 74LCX125MTR pin-compatible with standard 74LS125?

Yes - it uses identical SO-14 pinout and logic function (quad non-inverting 3-state buffer), but operates at 2.0–3.6 V instead of 4.75–5.25 V. Direct replacement is possible only if the host system's VCC and signal levels align with LCX specifications and 5 V tolerance is leveraged.

Can 74LCX125MTR drive a 50 Ω transmission line directly?

Yes - with ±24 mA output drive at 3.3 V, it can source/sink sufficient current to terminate a 50 Ω line at 3.3 V logic levels (VOL ≤ 0.55 V, VOH ≥ 2.2 V), provided trace length and capacitive load remain within 50 pF and 6 ns timing budget.

What is the maximum input frequency supported?

While not explicitly rated for clock frequency, its 5.2 ns max propagation delay and 1.0 ns max output skew support reliable operation up to ~100 MHz in well-terminated parallel buses; actual limit depends on PCB layout, load capacitance, and signal integrity margins.

Does 74LCX125MTR require external pull-up or pull-down resistors?

No - inputs have no bus-hold or weak termination; however, unused inputs must be tied to VCC or GND to prevent floating states that increase ICC and noise susceptibility. Outputs in high-impedance state do not require pull-ups unless needed for system-level default logic levels.