onsemi 74LVQ125SC

Overview

74LVQ125SC 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/50pF, and supports simultaneous switching into 75Ω transmission lines - used in bus buffering and level translation between ASICs and FPGAs.

For engineers reviewing the 74LVQ125SC datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed pin-to-pin skew (≤1.5ns), dynamic input voltage thresholds (VIHD = 2.0V, VILD = 0.8V at 3.3V), 3-STATE leakage <±2.5µA, and SOIC-14 JEDEC MS-012 package compatibility.

Technical Context

The 74LVQ125SC implements four independent CMOS buffer channels, each with separate 3-STATE enable control via dedicated input pins (1A–4A and 1B–4B per channel). Its output stage uses push-pull drivers optimized for low-noise 3.3V operation and incident-wave switching on controlled-impedance traces.

It meets JEDEC standard LV logic thresholds (VIH = 2.0V min, VIL = 0.8V max at VCC = 3.3V), supports −40°C to +85°C industrial temperature range, and features guaranteed AC performance including tPLH/tPHL ≤10.0ns and output-to-output skew ≤1.5ns - critical for synchronous data routing in high-density PCB layouts.

Key Specifications

Pinout & Package

74LVQ125SC is housed in a 14-lead Small Outline Integrated Circuit (SOIC) package per JEDEC MS-012, 0.150" narrow body, with 1.27mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC125APWR and 74ALVC125MTCX, the 74LVQ125SC offers tighter skew control (≤1.5ns vs ≥2.0ns) and guaranteed 75Ω incident-wave switching - making it preferred for timing-critical bus arbitration and high-fidelity test signal routing where deterministic edge behavior is required.

Availability

74LVQ125SC is available at Aetrix Electronics and suitable for industrial bus buffering, FPGA I/O expansion, ASIC-to-microcontroller interface, and test equipment signal conditioning requiring stable component supply and long-term lifecycle support.

Supply support for 74LVQ125SC 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 analog and discrete semiconductor manufacturer, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and communications infrastructure.

The 74LVQ125SC belongs to Fairchild's LVQ low-voltage logic family, engineered specifically for noise-immune, skew-controlled 3.3V bus interfacing in high-density embedded systems and test instrumentation.

FAQ

What is the maximum operating voltage for the 74LVQ125SC?

The 74LVQ125SC has an absolute maximum supply voltage of +7.0V, but its recommended operating range is strictly 2.0V to 3.6V. Operating outside this range risks violating logic threshold specifications and may cause unreliable 3-STATE behavior or increased ICC. The 74LVQ125SC is not rated for 5V operation - using it at 5V violates the Recommended Operating Conditions and voids parametric guarantees.

Does the 74LVQ125SC support true bidirectional data flow?

No, the 74LVQ125SC is a unidirectional non-inverting buffer with independent 3-STATE control per channel. Each channel accepts one input (A) and one enable (B), driving a single output (O). It lacks internal direction control or bus transceiver architecture. For bidirectional applications, the 74LVQ125SC must be paired with complementary devices or replaced with a true transceiver like the 74LVQ245 - the 74LVQ125SC itself does not support automatic direction sensing or dual-rail I/O.

What is the meaning of "incident wave switching into 75Ω" for the 74LVQ125SC?

"Incident wave switching into 75Ω" means the 74LVQ125SC output driver is characterized to deliver clean, monotonic edges onto 75Ω transmission lines without requiring external series termination - relying on controlled slew rate and output impedance matching. This specification is verified per Note 5 in the datasheet and applies across the commercial temperature range. The 74LVQ125SC achieves this via internal driver design, not external components.

Can unused inputs on the 74LVQ125SC be left floating?

No, unused inputs on the 74LVQ125SC must be actively tied HIGH or LOW - floating inputs are prohibited per Note 2 in the datasheet. Uncontrolled input voltages can cause excessive ICC, unpredictable 3-STATE behavior, or oscillation due to CMOS input stage metastability. This requirement applies to all four A and B inputs; tying them to VCC or GND via 10kΩ resistors is acceptable. Leaving any input floating invalidates the 74LVQ125SC's guaranteed AC and DC performance.

Is the 74LVQ125SC pin-compatible with standard 74LS125 or 74HC125 devices?

No, the 74LVQ125SC is not pin-compatible with 74LS125 or 74HC125. While all three share the same SOIC-14 footprint, their pin functions differ: the 74LVQ125SC uses separate A (data) and B (enable) inputs per channel, whereas 74LS125 and 74HC125 use active-low enable (/G) shared across pairs. Substituting the 74LVQ125SC without modifying enable logic and signal routing will result in functional failure - the 74LVQ125SC requires distinct control signal assignment per buffer channel.