Toshiba Semiconductor and Storage 74HC126D

Overview

74HC126D from Toshiba is a quad non-inverting bus buffer with 3-state outputs, designed for bidirectional data bus isolation in digital systems. It features active-low output enable (G̅), operates across 2.0–6.0 V supply, delivers 10 ns typical propagation delay at 6.0 V, and supports industrial temperature range (−40°C to +125°C) - used in microcontroller peripheral interfacing and memory address/data bus control.

For engineers reviewing the 74HC126D datasheet, 74HC126D pinout, 74HC126D application, or 74HC126D equivalent, key selection criteria include its active-low 3-state control logic, SOIC14 package compatibility, CMOS-level input thresholds, low ICC (≤4.0 µA max at 25°C), and guaranteed high-impedance output behavior per truth table.

Technical Context

The 74HC126D implements four independent non-inverting buffers, each with a dedicated active-low 3-state enable input (G̅). When G̅ = L, the output follows the input; when G̅ = H, the output enters high-impedance state - distinct from the 74HC125D's active-high enable. All inputs include ESD protection diodes rated for ±20 mA transient current.

It uses silicon gate C2MOS technology to achieve LSTTL-compatible speed (tpd ≤15 ns over −40°C to +85°C) while maintaining CMOS static power efficiency. Propagation delays are balanced (tPLH ≈ tPHL), and output drive capability is specified at ±7.8 mA at VCC = 6.0 V with VOH ≥ 5.9 V and VOL ≤ 0.18 V.

Key Specifications

Pinout & Package

74HC126D is housed in a 14-pin Small Outline Integrated Circuit (SOIC14) package, 3.9 mm wide, with 1.27 mm pitch and 0.13 g typical mass. Pin numbering follows standard JEDEC MS-012 outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC125D and SN74LV126A, the 74HC126D uniquely supports 6 V operation and provides active-low enable polarity - making it optimal for legacy 5 V systems with inverted control buses or mixed-voltage designs requiring extended supply headroom.

Availability

74HC126D is available at Aetrix Electronics and suitable for microcontroller bus isolation, memory address/data multiplexing, industrial PLC I/O expansion, and digital test equipment signal routing requiring stable component supply across automotive, industrial, and computing applications.

Supply support for 74HC126D 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

Toshiba Electronic Devices & Storage Corporation designs and manufactures high-reliability semiconductor components for industrial, automotive, and consumer applications, with emphasis on energy efficiency and system integration.

The 74HC126D belongs to Toshiba's HC-series CMOS logic family, engineered for drop-in replacement of legacy TTL devices while delivering lower power, wider voltage range, and enhanced noise immunity in digital interface and bus management applications.

FAQ

What is the key functional difference between 74HC126D and 74HC125D?

The 74HC126D uses an active-low 3-state enable input (G̅), meaning the output goes high-impedance when the enable pin is high. In contrast, the 74HC125D uses an active-high enable (G), so its output enters high-impedance when the enable pin is high. This polarity difference affects control logic design - the 74HC126D is selected when system-level enable signals are naturally active-low, avoiding external inverters. Both share identical pinout, electrical specs, and SOIC14 packaging.

Does 74HC126D support 3.3 V operation?

Yes, the 74HC126D fully supports 3.3 V operation within its specified supply range of 2.0 V to 6.0 V. At VCC = 3.3 V, VIH is guaranteed ≥2.31 V and VIL ≤0.99 V, providing >0.6 V noise margin. Output drive remains functional at ±4 mA, and propagation delay increases to ~15 ns typical - still compatible with most 3.3 V microcontrollers and FPGAs. No level-shifting circuitry is required for interfacing with 3.3 V logic.

What is the maximum output current rating for 74HC126D?

The 74HC126D is rated for ±7.8 mA output current per channel at VCC = 6.0 V, with VOH ≥5.9 V and VOL ≤0.18 V under those conditions. At 5.0 V, the guaranteed drive is ±6 mA. Exceeding these values risks violating VOH/VOL specifications or exceeding absolute maximum ratings (±35 mA per output). For sustained high-current loads, thermal derating applies - junction temperature must remain below 150°C, and total package power dissipation must stay ≤500 mW.

Can 74HC126D be used in automotive applications?

Yes, the 74HC126D is qualified for operation from −40°C to +125°C and meets AEC-Q100 stress test requirements for generic logic devices when sourced through Toshiba's automotive-grade channels. Its wide supply range (2.0–6.0 V), ESD-protected inputs (±20 mA), and low ICC (≤4.0 µA) make it suitable for body control modules, dashboard interfaces, and sensor signal conditioning in passenger vehicles - provided the application avoids safety-critical functions per Toshiba's unintended use restrictions.

How does the 74HC126D handle unused inputs?

Unused inputs on the 74HC126D must be tied to either VCC or GND - floating inputs are prohibited due to CMOS input structure susceptibility to noise-induced oscillation and increased ICC. For unused buffer channels, connect both the input (A) and enable (G̅) pins to GND to ensure the output remains in high-impedance state and prevents unintended current paths. This practice maintains device stability, minimizes power consumption, and avoids false triggering in adjacent channels.