STMicroelectronics 74LX1G126STR

Overview

74LX1G126STR from STMicroelectronics is a single-channel 3-state bus buffer with CMOS logic, designed for voltage-level translation between 1.65V–5.5V domains. It features 5V-tolerant inputs, 4.5ns max propagation delay at 3V, ±24mA output drive, and power-down protection enabling safe operation with VCC = 0V. It is used in low-power portable I²C/SPI data path isolation and mixed-voltage microcontroller GPIO expansion.

For engineers reviewing the 74LX1G126STR datasheet, 74LX1G126STR pinout, 74LX1G126STR application, or 74LX1G126STR equivalent, key selection criteria include 5V input tolerance, symmetrical 24mA drive at 3V, 1.65V minimum operating voltage, high-impedance enable timing (tPLZ/tPZL ≤ 5.5ns), and SOT23-5L package compatibility with space-constrained PCB layouts.

Technical Context

This device implements a single non-inverting buffer with active-low 3-state enable (1G), supporting bidirectional voltage translation without direction control. Its C2MOS process enables latch-up immunity and allows input voltages up to 7V regardless of VCC state.

Power-down protection ensures inputs and outputs remain high-impedance and non-damaging when VCC = 0V, while symmetrical |IOH| = |IOL| = 24mA (min) at VCC = 3V guarantees matched rise/fall behavior and balanced signal integrity in push-pull or open-drain emulation scenarios.

Key Specifications

Pinout & Package

SOT23-5L package: 5-pin surface-mount, 1.3mm height, 2.8 × 1.5mm footprint, tape-and-reel compatible (TR).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G126DBVR and NC7SZ126P5X, the 74LX1G126STR uniquely combines 7V input tolerance, VCC = 0V safe operation, and −55°C to +125°C qualification - making it the only option for automotive body controllers and industrial fieldbus nodes requiring robust mixed-voltage interoperability.

Availability

74LX1G126STR is available at Aetrix Electronics and suitable for industrial sensor interfaces, low-power wearable MCU expansions, and automotive body control modules requiring stable component supply across extended temperature and mixed-voltage conditions.

Supply support for 74LX1G126STR 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, specializing in automotive, industrial, and power management ICs with broad manufacturing and quality certifications.

The 74LX series targets low-voltage, high-speed logic applications in space-constrained and mixed-supply systems, emphasizing robustness, wide voltage operation, and seamless integration with legacy 5V infrastructure.

FAQ

Can the 74LX1G126STR operate with VCC = 0V?

Yes - its power-down protection circuitry allows inputs and outputs to tolerate 0–7V signals even when VCC is unpowered or disconnected. This prevents latch-up and enables safe hot-swap operation in modular systems where subsystems power up/down independently.

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

At VCC = 3V, the device maintains ≤4.5ns propagation delay with CL = 50pF and RL = 500Ω, confirming reliable operation into typical PCB traces and 2–3 standard CMOS inputs. For CL > 50pF, edge rate degrades linearly; design margin requires derating to ≤30pF for <5ns timing-critical paths.

Does the 74LX1G126STR require external pull-up resistors on its output?

No - the output is a standard CMOS totem-pole structure capable of actively driving both HIGH and LOW states. Pull-ups are unnecessary unless implementing wired-OR logic or I²C open-drain emulation, in which case external resistors must be sized per bus capacitance and speed requirements.

How does the 74LX1G126STR compare to standard 74HC126 in mixed-voltage designs?

Unlike 74HC126, which requires VCC ≥ 4.5V for 5V input tolerance and lacks power-down protection, the 74LX1G126STR accepts 5V inputs at VCC = 1.8V and remains safe with VCC = 0V. Its lower VCC range and integrated clamps eliminate external components needed for HC-series interfacing.