Texas Instruments SN74LVC126ABQAR

Overview

SN74LVC126ABQAR from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for 1.65V–3.6V V_CC operation. It supports 5.5V-tolerant inputs, delivers ≤4.7ns propagation delay at 3.3V, operates across –40°C to +125°C, and enables voltage translation in mixed 3.3V/5V systems-commonly used in SSDs, AV receivers, and portable audio docks.

For engineers reviewing the SN74LVC126ABQAR datasheet, SN74LVC126ABQAR pinout, SN74LVC126ABQAR application, or SN74LVC126ABQAR equivalent, key selection criteria include 3-state output timing (t_pd, t_en, t_dis), input overvoltage tolerance, thermal performance in WQFN-14, and compatibility with high-speed digital buses requiring low ground bounce (<0.8V) and controlled undershoot (>2V).

Technical Context

The SN74LVC126ABQAR implements four identical non-inverting buffers (Y = A), each controlled by a dedicated active-low output-enable (OE) input. Its CMOS design ensures rail-to-rail output swing (V_OH ≥ V_CC – 0.3V, V_OL ≤ 0.3V at 125°C) and supports bidirectional voltage translation: 5V inputs drive 3.3V outputs without level shifters.

Each buffer provides up to 24mA output drive at 3V, with fast switching (t_pd = 2.5–4.5ns typ. at 3.3V) and robust ESD protection (±2000V HBM). The BQA package features an exposed thermal pad tied to GND, enabling efficient heat dissipation (R_θJA = 102.3°C/W) in space-constrained industrial and consumer applications.

Key Specifications

Pinout & Package

SN74LVC126ABQAR uses a 14-pin WQFN (BQA) package measuring 3mm × 2.5mm with an exposed thermal pad connected to GND. Pin 7 is GND; Pin 14 is V_CC; Pins 1, 4, 10, 13 are independent OE inputs; Pins 2, 5, 9, 12 are A inputs; Pins 3, 6, 8, 11 are Y outputs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffer applications.

Compared with SN74LVC125A, SN74LVC126ABQAR offers native active-low OE alignment with common microcontroller GPIO configurations; compared with 74LVC126PW, it delivers superior thermal efficiency and 40% smaller board area-critical for SSD M.2 modules and ultra-thin audio docks.

Availability

SN74LVC126ABQAR is available at Aetrix Electronics and suitable for SSD data path isolation, AV receiver signal routing, and portable audio dock interface applications requiring stable component supply, full -40°C to +125°C qualification, and RoHS-compliant WQFN packaging.

Supply support for SN74LVC126ABQAR 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in logic IC design and automotive-grade qualification.

The SN74LVC126ABQAR belongs to TI's LVC (Low-Voltage CMOS) logic family, engineered for high-speed, low-power, mixed-voltage interoperability in consumer, industrial, and communications systems where signal integrity and thermal efficiency are critical.

FAQ

What is the maximum operating frequency supported by the SN74LVC126ABQAR?

The SN74LVC126ABQAR does not specify a hard maximum clock frequency, but its typical propagation delay of 2.5–4.5ns at 3.3V supports reliable operation in digital buses up to approximately 100MHz. System-level timing depends on load capacitance, trace impedance, and signal integrity margins-TI recommends verifying setup/hold times in actual PCB layouts using the device's published t_pd, t_en, and t_dis values from the SN74LVC126ABQAR datasheet.

Can the SN74LVC126ABQAR safely interface a 5V microcontroller with a 3.3V FPGA?

Yes-the SN74LVC126ABQAR accepts input voltages up to 5.5V while operating from a 3.3V V_CC, making it ideal for down-translation from 5V logic to 3.3V domains. Its 5.5V-tolerant inputs eliminate external level shifters, and its 3.3V-compatible outputs meet VIH/VIL thresholds of standard 3.3V CMOS interfaces. Ensure OE pins are actively driven or pulled low via resistor to avoid floating states during power transitions.

How should the thermal pad on the SN74LVC126ABQAR BQA package be connected?

The exposed thermal pad on the SN74LVC126ABQAR must be soldered directly to a PCB ground plane using at least four thermal vias (0.3mm diameter, spaced evenly). This connection serves both thermal management (reducing R_θJA from 102.3°C/W to near theoretical minimum) and electrical stability-TI specifies that improper grounding causes increased ground bounce and potential latch-up. Do not leave the pad unconnected or float it.

Is the SN74LVC126ABQAR pin-compatible with other packages in the SN74LVC126A family?

No-while functionally identical, the SN74LVC126ABQAR (WQFN-14) has a different pinout than SOIC (D), SSOP (DB), or TSSOP (PW) variants. For example, Pin 7 is GND in BQA but Pin 7 is 2Y in D/DB/PW packages. Always consult the specific package drawing: Figure 4-2 in the SN74LVC126ABQAR datasheet shows the WQFN top view, and Table 4-1 confirms pin functions for BQA only.

What is the recommended bypass capacitor for the SN74LVC126ABQAR V_CC pin?

Texas Instruments recommends a 0.1µF ceramic capacitor placed as close as possible to the SN74LVC126ABQAR V_CC pin (Pin 14), with short, low-inductance traces to the GND pad. For systems with high-frequency noise or multiple logic devices, paralleling a 1µF capacitor improves low-frequency decoupling. Avoid electrolytic or tantalum capacitors due to higher ESR; X7R or X5R dielectrics are preferred for stable performance across –40°C to +125°C.