STMicroelectronics 74LVX138MTR

Overview

74LVX138MTR from STMicroelectronics is a low-voltage CMOS 3-to-8 line decoder with inverting outputs, 5V-tolerant inputs, and pin/function compatibility with standard 74-series 138 devices. It operates from 2V to 3.6V, delivers 5.5ns typical propagation delay at 3.3V, supports 4mA output drive, and features power-down input protection enabling safe 5V-to-3.3V interfacing in memory address decoding systems.

For engineers reviewing the 74LVX138MTR datasheet, 74LVX138MTR pinout, 74LVX138MTR application, or 74LVX138MTR equivalent, key selection criteria include its 5V-tolerant input voltage range (0–5.5V), symmetrical output impedance (|IOH| = IOL ≥ 4mA), low quiescent current (ICC ≤ 4µA), balanced tPLH/tPHL delays, and guaranteed operation down to –55°C for industrial and battery-powered embedded control.

Technical Context

The 74LVX138 implements a fully decoded 3-bit binary input (A, B, C) to eight active-low outputs (Y0–Y7), controlled by three enable inputs (G1, G2A, G2B) with hierarchical logic: all outputs go high if G1 is low OR either G2A or G2B is high. Its sub-micron C2MOS process enables true CMOS low power while maintaining high speed.

Input protection allows 0–7V input voltage regardless of VCC, supporting hot-swap and mixed-voltage system interfacing. All inputs/outputs include 2kV ESD protection, and dynamic noise parameters (VOLP = 0.3V typ., tOSLH ≤ 1.5ns) are specified under defined load and transition conditions (CL = 50pF, tr/tf = 3ns).

Key Specifications

Pinout & Package

74LVX138MTR is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-012, tape-and-reel format (MTR suffix), with 1.27mm pitch and body dimensions 9.8 × 5.8 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 inverting decoder applications.

Compared with 74LVC138PW and SN74LV138APWR, the 74LVX138MTR uniquely balances 5V-tolerance, 4µA quiescent current, and 5.5ns speed - making it optimal for battery-powered, mixed-voltage, and extended-temperature embedded decoding where reliability and power efficiency are co-prioritized.

Availability

74LVX138MTR is available at Aetrix Electronics and suitable for memory address decoding, peripheral select logic, low-power sensor hubs, and battery-powered instrumentation requiring stable component supply across industrial temperature grades and long-term production cycles.

Supply support for 74LVX138MTR 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 broad portfolio coverage from microcontrollers to analog and discrete devices.

The 74LVX series was designed specifically for low-voltage, low-noise, 5V-tolerant logic interfacing in portable and mixed-signal systems - bridging legacy 5V infrastructure with emerging 3.3V and lower-core digital architectures.

FAQ

Is 74LVX138MTR pin-compatible with standard 74HC138 or 74LS138?

Yes - it is pin- and function-compatible with 74-series 138 decoders, including identical pin numbering (A/B/C, G1/G2A/G2B, Y0–Y7, VCC, GND). However, unlike 74LS138, it requires no pull-up resistors on outputs and operates natively at 3.3V with 5V-tolerant inputs.

Can 74LVX138MTR safely interface a 5V microcontroller to a 3.3V FPGA?

Yes - its 5V-tolerant inputs accept 0–5.5V logic levels regardless of VCC, and its 3.3V-compatible outputs meet FPGA input thresholds. No level-shifting components are needed, provided the FPGA's input clamp diodes are not relied upon for sustained 5V injection.

What is the maximum output capacitive load supported at full speed?

The device is characterized up to 50pF load capacitance, with tPD = 8.0ns (max) and tOSLH ≤ 1.5ns at VCC = 3.3V. Driving >50pF increases propagation delay nonlinearly and may degrade VOLP; for >100pF loads, consider buffering or reducing trace length.

Does 74LVX138MTR support partial power-down modes?

No - it has no dedicated sleep or standby mode. However, its power-down input protection allows inputs to float or remain at 5V while VCC is unpowered, preventing backfeeding or latch-up. Quiescent current remains ≤4µA only when VCC is applied and inputs are static.