Texas Instruments SN74HC126PWTG4

Overview

SN74HC126PWTG4 from Texas Instruments is a quadruple non-inverting buffer with 3-state outputs, designed for bus interface and signal enable functions in digital logic systems. It operates across 2 V to 6 V supply voltage, supports –40°C to +85°C ambient temperature, delivers ≤31 ns propagation delay at 6 V (CL = 50 pF), and drives up to 10 LSTTL loads - commonly used in bidirectional data bus control and level-shifting applications.

For engineers reviewing the SN74HC126PWTG4 datasheet, SN74HC126PWTG4 pinout, SN74HC126PWTG4 application, or SN74HC126PWTG4 equivalent, key selection criteria include its TSSOP-14 package footprint, 3-state output control per channel, CMOS input compatibility, and guaranteed performance under industrial temperature and voltage ranges.

Technical Context

This device implements four independent positive-logic buffers (Y = A) with individual 3-state output enables (OE), enabling per-channel bus isolation. Each output features balanced CMOS drive capability - sourcing and sinking up to ±7.8 mA at 6 V while maintaining VOH ≥ 5.34 V and VOL ≤ 0.33 V.

Input structure uses standard high-impedance CMOS with ≤10 pF capacitance and ±1 µA leakage; output disable state exhibits ≤±0.5 µA three-state leakage (IOZ). Propagation delay (tpd), enable delay (ten), and disable delay (tdis) are all specified down to 11 ns at 6 V/CL = 50 pF, supporting reliable timing in synchronous digital interfaces.

Key Specifications

Pinout & Package

TSSOP-14 package (5.00 mm × 4.40 mm body size), 0.65 mm lead pitch, thin shrink small-outline profile optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC126PWTG4, SN74HCT126PW offers superior noise immunity in 5 V TTL environments but sacrifices supply voltage flexibility, while 74LVC126APW delivers significantly faster switching and lower-voltage operation at the cost of reduced 6 V compatibility and higher static current.

Availability

SN74HC126PWTG4 is available at Aetrix Electronics and suitable for industrial control systems, embedded instrumentation, and legacy interface bridging requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74HC126PWTG4 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 logic solutions, with decades of expertise in high-reliability logic families.

The SN74HC126PWTG4 belongs to TI's industry-standard HC (High-Speed CMOS) logic family, engineered for low-power, wide-supply digital interfacing in industrial, automotive, and communications equipment.

FAQ

What is the maximum capacitive load SN74HC126PWTG4 can reliably drive?

SN74HC126PWTG4 is characterized for optimal timing performance with ≤70 pF total load capacitance per output. While it can drive larger loads, exceeding this value increases propagation delay and transition time - for example, tpd rises from 11 ns to 15 ns at 6 V when CL increases from 50 pF to 150 pF. For robust design, keep trace + receiver input capacitance under 70 pF or add series termination to limit peak current.

Does SN74HC126PWTG4 support mixed-voltage operation between input and output sides?

No - SN74HC126PWTG4 does not provide true level-shifting isolation. Its inputs and outputs share the same VCC rail; VIH/VIL thresholds scale with VCC (e.g., VIH = 3.15 V at VCC = 4.5 V). To interface 3.3 V logic to 5 V logic, operate SN74HC126PWTG4 at 5 V and ensure upstream 3.3 V drivers meet the 5 V–compatible VIH minimum (≥3.15 V), which most 3.3 V CMOS outputs satisfy.

How should unused inputs and outputs be handled on SN74HC126PWTG4?

Unused inputs must be terminated to VCC or GND - floating CMOS inputs cause excessive current draw and potential oscillation. A 10-kΩ pull-up or pull-down resistor is recommended. Unused outputs may be left unconnected (floating) since they present high impedance in 3-state mode; do not tie them directly to VCC or GND, as this violates absolute maximum ratings and risks damage.

What is the thermal resistance (RθJA) of SN74HC126PWTG4 in its TSSOP-14 package?

The junction-to-ambient thermal resistance (RθJA) for SN74HC126PWTG4 in the PW (TSSOP-14) package is 151.7°C/W, per TI's SCLS103F datasheet. This value assumes standard JEDEC 2-layer board conditions. With typical ICC < 80 µA and output currents well below 35 mA, self-heating is negligible in most applications - no heatsink required under normal operation.

Can SN74HC126PWTG4 replace SN74LS126 in existing designs?

SN74HC126PWTG4 can functionally replace SN74LS126 in many cases due to matching pinout and 3-state buffer behavior, but requires validation of voltage and timing margins. Unlike LS TTL, SN74HC126PWTG4 draws far less supply current (µA vs. mA), has higher input impedance, and exhibits slower edge rates at low VCC - verify setup/hold times and noise immunity in the target system before substitution.