onsemi 74LVQ125SCX

Overview

74LVQ125SCX from Fairchild Semiconductor is a low-voltage quad non-inverting buffer IC with 3-STATE outputs, designed for 3.3V logic interfacing in space-constrained digital systems. It operates from 2.0V to 3.6V, delivers ±12mA drive strength, guarantees ≤10.0ns propagation delay at 3.3V, and supports simultaneous switching into 75Ω transmission lines - used in bus buffering and level translation between FPGA I/O and peripheral logic.

For engineers reviewing the 74LVQ125SCX datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 3.3V-compatible input thresholds (VIH = 2.0V min), output disable timing (tPZL ≤ 11.0ns), simultaneous skew control (tOSLH ≤ 1.5ns), and SOIC-14 package compatibility with JEDEC MS-012 footprint.

Technical Context

This device implements four independent CMOS buffer channels, each with separate 3-STATE enable control via dedicated input pins (1A–4A and 1B–4B per channel). All outputs are actively driven HIGH/LOW or placed in high-impedance state based on input logic levels - no internal latching or clocking logic is present.

It targets low-noise, low-power 3.3V system interconnects where controlled edge rates (≥125 mV/ns), incident-wave switching integrity, and deterministic pin-to-pin skew (<1.5ns) are required - verified across −40°C to +85°C with VCC = 3.3V ±0.3V and CL = 50pF.

Key Specifications

Pinout & Package

74LVQ125SCX is housed in a 14-lead Small Outline Integrated Circuit (SOIC) package per JEDEC MS-012, 0.150" narrow body (Package Number M14A), with standard 1.27mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC125APWR and 74ALVC125MTCX, the 74LVQ125SCX uniquely balances 75Ω transmission-line compatibility, 1.5ns skew control, and 3.3V-specific noise immunity - making it optimal for industrial backplanes and legacy PCI derivatives where signal fidelity outweighs raw speed or ultra-low ICC.

Availability

74LVQ125SCX is available at Aetrix Electronics and suitable for PCI bus interface, FPGA I/O expansion, and industrial control backplane applications requiring stable component supply, long-term lifecycle support, and consistent SOIC-14 packaging.

Supply support for 74LVQ125SCX 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

Fairchild Semiconductor was a U.S.-based semiconductor manufacturer specializing in analog and mixed-signal ICs, power management, and logic devices before its acquisition by ON Semiconductor in 2016.

The 74LVQ125SCX belongs to Fairchild's LVQ low-voltage logic family, engineered specifically for robust 3.3V system interfacing with emphasis on transmission-line integrity, skew control, and noise immunity in industrial and telecom infrastructure.

FAQ

What is the recommended operating voltage range for the 74LVQ125SCX?

The 74LVQ125SCX is specified to operate reliably from 2.0V to 3.6V. Operation outside this range may cause undefined behavior or damage. At VCC = 3.3V ±0.3V, all AC and DC parameters-including propagation delay, VIH/VIL thresholds, and output drive-are fully guaranteed across −40°C to +85°C. The 74LVQ125SCX must not be operated at 5V, as absolute maximum rating is 7.0V but functional specs are not validated above 3.6V.

Does the 74LVQ125SCX support true bidirectional data flow?

No, the 74LVQ125SCX is a unidirectional non-inverting buffer with independent 3-STATE control per channel. Each channel has two inputs (A and B) and one output (O): A is the data input, B is the active-HIGH enable, and O reflects A when B = HIGH. It does not auto-detect direction or support bus transceiver functionality. For bidirectional applications, discrete direction-control logic or a dedicated transceiver like the 74LVX245 must be used alongside the 74LVQ125SCX.

What is the meaning of "guaranteed incident wave switching into 75Ω" for the 74LVQ125SCX?

This specification means the 74LVQ125SCX output driver is characterized to launch clean, unterminated signals onto 75Ω transmission lines without overshoot or reflection-induced timing errors-verified across temperature and voltage. It allows direct connection to coaxial or controlled-impedance PCB traces without external series termination resistors. This capability is unique to the LVQ family and is not guaranteed in standard LVC or ALVC buffers like the SN74LVC125APWR.

Can unused inputs on the 74LVQ125SCX be left floating?

No, unused inputs on the 74LVQ125SCX must be tied HIGH or LOW-never left floating. Per Fairchild's Recommended Operating Conditions (Note 2), floating inputs can cause increased ICC, erratic output states, or latch-up due to internal CMOS gate instability. For unused channels, tie both A and B inputs to VCC (for disabled HIGH-output state) or GND (for disabled LOW-output state), depending on system fail-safe requirements.

Is the 74LVQ125SCX pin-compatible with the standard 74LS125 or 74HC125?

No, the 74LVQ125SCX is not pin-compatible with 74LS125 or 74HC125. While all three share the same SOIC-14 pin count and basic function (quad 3-STATE buffer), their pin assignments differ: 74LVQ125SCX uses dual-input per channel (A/B), whereas 74LS125 and 74HC125 use single data input + separate active-LOW enable per channel. Substituting them requires PCB redesign. The 74LVQ125SCX pinout matches only other LVQ-series parts such as 74LVQ126SCX.