STMicroelectronics 74LVX238TTR

Overview

74LVX238TTR from STMicroelectronics is a low-voltage CMOS 3-to-8 line decoder with 5V-tolerant inputs, operating from 2V to 3.6V supply. It features 5.5ns typical propagation delay at 3.3V, ±4mA symmetrical output drive, and true 5V input compatibility for mixed-voltage interfacing in memory address decoding systems.

For engineers reviewing the 74LVX238TTR datasheet, 74LVX238TTR pinout, 74LVX238TTR application, or 74LVX238TTR equivalent, key selection criteria include enable-input logic architecture (G1 active-low, G2A/G2B active-high), 3.3V system integration with 5V signal sources, low-noise output (0.3V VOLP typ.), and cascade-ready triple-enable topology for multi-chip address decoding.

Technical Context

The 74LVX238 implements standard 3-bit binary decoding with three independent enable inputs (G1, G2A, G2B) that must satisfy G1 = LOW and G2A = G2B = LOW for valid output activation. Its logic function is non-inverting: selected Yx output goes HIGH while all others remain LOW.

Input protection allows 0–7V input voltage regardless of VCC, enabling robust level translation between 5V peripherals and 3.3V logic domains. All outputs exhibit matched tPLH/tPHL delays and ≤1.5ns skew across load conditions, supporting timing-critical address decode paths in SRAM/Flash memory subsystems.

Key Specifications

Pinout & Package

TSSOP16 package: 4.9–5.1mm width, 6.2–6.6mm length, 0.65mm pitch, 1.2mm max height, lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV138APWR and 74LVC138PW, the 74LVX238TTR uniquely delivers guaranteed 5V input tolerance at 3.3V supply - a critical differentiator for legacy interface preservation, while maintaining ultra-low quiescent current and low-noise operation essential for portable and automotive applications.

Availability

74LVX238TTR is available at Aetrix Electronics and suitable for memory address decoding, industrial I/O expansion, low-power sensor hubs, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74LVX238TTR 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 microcontrollers, power management ICs, sensors, and discrete components for industrial, automotive, and consumer markets.

The LVX logic family targets low-voltage, low-power, and mixed-signal interface applications - specifically engineered for 3.3V systems needing 5V input compatibility, ESD robustness, and minimal dynamic noise in space-constrained or battery-operated devices.

FAQ

Can 74LVX238TTR operate with VCC = 2.5V while accepting 5V inputs?

Yes. The device is explicitly rated for VCC = 2V to 3.6V and input voltage range of 0V to 5.5V, independent of supply voltage. This allows safe 5V signal reception even at minimum 2V VCC, making it ideal for brown-out or battery-depleted conditions where input sources remain at nominal voltage.

What is the maximum capacitive load this decoder can drive reliably?

The 74LVX238TTR guarantees ±4mA output drive into resistive loads and has been characterized up to 50pF capacitive load in AC specs. For reliable signal integrity beyond 50pF, series termination or buffer staging is recommended - especially at 3.3V supply where VOH drops to 2.48V at 4mA sink.

How does the triple-enable structure improve cascade reliability compared to single-enable decoders?

The G1 (active-low) plus G2A/G2B (active-high) configuration allows hierarchical enable trees where upper-level decoders control G2A/G2B while G1 serves as global reset or power-gate signal. This eliminates race conditions during power-up and enables glitch-free enable sequencing across multiple decoder stages in large memory maps.

Is the 74LVX238TTR pin-compatible with standard 74HC138 or 74LS138 packages?

No. While functionally compatible with 74-series 138 decoders, the 74LVX238TTR uses TSSOP16 packaging (4.4–4.48mm width) versus SOIC16 (3.9mm width) for HC/LS variants. Pin numbering and signal mapping match the industry-standard 138 layout (A/B/C, G1/G2A/G2B, Y0–Y7), but physical footprint and thermal characteristics differ significantly.