STMicroelectronics 74V1G125STR

Overview

74V1G125STR from STMicroelectronics is a single-channel 3-state bus buffer IC designed for voltage-level translation and bidirectional bus isolation in mixed-voltage systems. It operates from 2V to 5.5V, delivers 3.8ns typical propagation delay at 5V, supports 0–7V input tolerance independent of VCC, and features symmetrical 8mA output drive capability. It is used in 5V-to-3V interface circuits within industrial control backplanes.

For engineers reviewing the 74V1G125STR datasheet, 74V1G125STR pinout, 74V1G125STR application, or 74V1G125STR equivalent, key selection criteria include 3-state enable timing (tPZH/tPLZ ≤ 8ns), input overvoltage tolerance, rail-to-rail input compatibility, and SOT23-5L thermal performance under continuous 8mA sink/source loads.

Technical Context

The 74V1G125STR implements a CMOS-based non-inverting buffer with active-high 3-state enable (1G). Its input structure accepts voltages up to 7V regardless of VCC, enabling safe interfacing between disparate supply domains without external clamping diodes.

It uses sub-micron C2MOS technology with double-layer metal wiring, delivering balanced tPLH ≅ tPHL propagation delays and power-down protection that prevents current injection during VCC=0 operation - critical for hot-swap and partial-power-down systems.

Key Specifications

Pinout & Package

SOT23-5L package: compact 5-pin surface-mount outline with 0.95mm pitch, 1.45mm height, and JEDEC-compliant thermal profile for reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G125DBVR and 74AHC1G125W5-7, the 74V1G125STR uniquely supports 0–7V input tolerance at any VCC ≥2V - making it the only option for legacy 5V bus interfacing in powered-down subsystems without redesigning input protection.

Availability

74V1G125STR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, medical infusion pump controllers, and automated test equipment requiring stable component supply across extended temperature and mixed-voltage conditions.

Supply support for 74V1G125STR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The 74V series targets high-speed, low-power logic interface applications in harsh environments - emphasizing robustness, wide supply range, and interoperability across legacy and modern voltage domains.

FAQ

Can the 74V1G125STR safely interface a 5V microcontroller with a 3.3V FPGA when VCC = 3.3V?

Yes. With VCC = 3.3V, the 74V1G125STR accepts 0–7V on input pin 1A, so 5V logic HIGH from the microcontroller is fully compliant and will not damage the device or violate VIH thresholds. VOH remains ≥2.9V at IO = −50µA, meeting 3.3V FPGA VIH requirements.

What is the maximum capacitive load this buffer can drive while maintaining 3.8ns propagation delay?

The 3.8ns tPD is specified at CL = 15pF and VCC = 5.0V. At CL = 50pF, tPD increases to 4.3ns. For designs requiring ≤4ns delay, total load (including trace and input capacitance) must stay below 25pF - verified by AC characterization in the official ST datasheet Rev 4, page 3.

Does the 74V1G125STR require external pull-up or pull-down resistors on the 1G enable pin?

No. The 1G input has CMOS-compatible thresholds (VIH ≥ 0.7VCC, VIL ≤ 0.3VCC) and <1µA leakage, so direct connection to a GPIO or logic rail is sufficient. External resistors are unnecessary unless system-level noise immunity requires stronger static biasing beyond the device's inherent 28% VCC noise margin.

How does the power-down protection function when VCC is disconnected during system maintenance?

When VCC = 0V, the input protection diodes remain reverse-biased up to +7V on 1A or 1G due to internal circuitry - preventing current flow into the die. This avoids latch-up and allows live insertion of boards into backplanes where other slots remain powered, as confirmed in Absolute Maximum Ratings and Input Equivalent Circuit diagrams (pages 2 and 3).