Texas Instruments SN74AHC126DG4

Overview

SN74AHC126DG4 from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for digital signal routing and bus isolation in 2V–5.5V systems. It delivers 3.8 ns typical propagation delay at 5 V, supports ±25 mA output drive, and features balanced CMOS outputs enabling bidirectional bus control in industrial control interfaces and microcontroller peripheral expansion.

For engineers reviewing the SN74AHC126DG4 datasheet, SN74AHC126DG4 pinout, SN74AHC126DG4 application, or SN74AHC126DG4 equivalent, this page provides verified functional modes, thermal performance data, latch-up immunity (≥250 mA), and precise TSSOP-14 package implementation details required for signal integrity validation and PCB layout planning.

Technical Context

The SN74AHC126DG4 implements four identical non-inverting buffer channels, each with separate active-low output enable (OE) control and positive-logic Y = A functionality. Its 3-state outputs support high-impedance tri-state operation during power sequencing or bus arbitration, with guaranteed low leakage (±0.25 µA) and rail-to-rail output voltage swing (0 to VCC).

Designed for mixed-voltage interfacing, it operates across 2V–5.5V supply range with input thresholds scaling proportionally (e.g., VIH = 3.85 V at VCC = 5.5 V). The device uses standard CMOS inputs requiring fast edge rates (≤20 ns/V at 5 V) and mandates termination of unused inputs to VCC or GND to prevent floating-node oscillation.

Key Specifications

Pinout & Package

TSSOP-14 (PW) package: 5 mm × 6.4 mm body size, 14-pin surface-mount, RoHS-compliant, moisture sensitivity level 1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT126PW and 74LVC126APW, the SN74AHC126DG4 uniquely bridges 2–5.5 V operation while maintaining 3.8 ns speed and industrial temperature range - making it the only option for scalable voltage-domain designs requiring single-part logistics across 2.5 V, 3.3 V, and 5 V subsystems.

Availability

SN74AHC126DG4 is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, microcontroller peripheral bus isolation, LED driver interface logic, and digital signal enable/disable applications requiring stable component supply and long-term production continuity.

Supply support for SN74AHC126DG4 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 over 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHC126DG4 belongs to TI's AHC logic family - engineered for high-speed, low-power, wide-voltage digital interfacing in industrial automation, test equipment, and programmable logic controllers.

FAQ

What is the maximum recommended operating voltage for SN74AHC126DG4?

The SN74AHC126DG4 has an absolute maximum VCC rating of 7 V, but its recommended operating range is strictly 2 V to 5.5 V per TI SCLS257N. Operating above 5.5 V voids parametric guarantees and risks permanent damage. At 5.5 V, VIH reaches 3.85 V and VOL remains ≤0.1 V under 50 µA load - confirming robust noise margin within spec.

How does SN74AHC126DG4 handle unused inputs and outputs?

Unused inputs on the SN74AHC126DG4 must be tied to VCC or GND - never left floating - to prevent excessive current draw and oscillation, per TI application note SCBA004. Unused 3-state outputs may be left disconnected, but if bus termination is required, a 10 kΩ pull-up/down resistor ensures known voltage in high-Z state without exceeding leakage specs (±2.5 µA).

Can SN74AHC126DG4 drive transmission lines directly?

Yes - the SN74AHC126DG4 can drive short PCB traces (<10 cm) and unterminated stubs typical in backplane or board-level interconnects. Its 3.8 ns propagation delay and ±8 mA drive at 5 V support clean edges into 50 Ω loads, but for longer lines or impedance-critical applications, external series termination (e.g., 33 Ω) is recommended to suppress reflections observed in TI's characteristic impedance modeling.

What thermal considerations apply to SN74AHC126DG4 in TSSOP-14 package?

The SN74AHC126DG4 in PW package has RθJA = 147.7 °C/W (JEDEC std). At 8 mA per channel and 5 V supply, worst-case power dissipation is ~17 mW - resulting in <3°C junction rise above ambient. No heatsink is needed, but ensure ≥200 mils of copper pour under pin 7 (GND) and pin 14 (VCC) to maintain thermal stability during sustained 85°C operation.

Is SN74AHC126DG4 compatible with 3.3 V microcontrollers?

Yes - the SN74AHC126DG4 is fully compatible with 3.3 V microcontrollers. At VCC = 3.3 V, VIH = 2.1 V and VIL = 0.9 V provide 1.2 V noise margin, while tPLH/tPHL remain ≤8 ns (typical) and output drive stays at ±4 mA. Its 2–5.5 V range allows direct connection to 3.3 V GPIO without level shifters, confirmed by TI's switching characteristics tables for 3.3 V ±0.3 V operation.