Texas Instruments SN74HC126PWR

Overview

SN74HC126PWR from Texas Instruments is a quadruple 3-state buffer IC used for digital signal enablement and bus isolation in CMOS logic systems. It operates across 2 V–6 V supply, supports –40°C to +85°C ambient, delivers propagation delay ≤31 ns at 6 V (CL = 50 pF), and features balanced CMOS outputs capable of ±7.8 mA drive. It is commonly deployed in 4-bit data bus control where channel-independent output gating is required.

For engineers reviewing the SN74HC126PWR datasheet, SN74HC126PWR pinout, SN74HC126PWR application, or SN74HC126PWR equivalent, key selection considerations include its 3-state output behavior, voltage-level compatibility with LSTTL and CMOS loads, thermal resistance (RθJA = 151.7°C/W), fanout capability (up to 10 LSTTL), and TSSOP-14 package constraints for high-density PCB layouts.

Technical Context

The SN74HC126PWR implements four independent non-inverting buffers, each with a dedicated 3-state output enable (OE) input and Boolean function Y = A. Its CMOS architecture ensures low static power consumption (ICC ≤ 80 µA at 6 V) while maintaining rail-to-rail output swing and symmetrical sourcing/sinking capability.

All channels operate synchronously under shared supply (VCC) and ground (GND), with no internal inter-channel coupling. Input thresholds scale with VCC (VIH = 0.7×VCC min, VIL = 0.3×VCC max), and output states are strictly defined by OE: logic high enables Y = A; logic low forces high-impedance (Z) output with leakage ≤ ±0.5 µA.

Key Specifications

Pinout & Package

TSSOP-14 package (5.00 mm × 4.40 mm body size, 0.65 mm lead pitch), thermally enhanced for surface-mount assembly in space-constrained industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC126PWR, SN74LVC126APW offers superior speed and lower voltage operation but sacrifices 5 V/6 V compatibility, while MC74HC126ADTR2G provides identical logic behavior with extended temperature qualification-neither is pin-compatible drop-in replacements without verifying board-level thermal and voltage design margins.

Availability

SN74HC126PWR is available at Aetrix Electronics and suitable for industrial automation, test equipment, and embedded control applications requiring stable component supply, long-term manufacturability, and consistent TSSOP-14 packaging.

Supply support for SN74HC126PWR 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 over 50 years of innovation in high-reliability logic families.

The SN74HC126PWR belongs to TI's 74HC high-speed CMOS logic product line, designed for low-power, voltage-flexible digital interfacing in industrial, communications, and computing systems where noise immunity and wide supply tolerance are critical.

FAQ

What is the maximum capacitive load the SN74HC126PWR can drive while meeting datasheet timing specs?

The SN74HC126PWR is characterized for CL ≤ 50 pF in switching specifications (tpd, ten, tdis), with typical performance maintained up to 70 pF per output. Driving >70 pF increases propagation delay nonlinearly and may violate setup/hold margins in synchronous systems. For larger loads, add a series resistor to limit peak output current within ±7.8 mA absolute maximum rating.

Can unused inputs on the SN74HC126PWR be left floating?

No. Unused inputs on the SN74HC126PWR must be terminated to either VCC or GND to prevent undefined logic states, increased ICC, and potential oscillation due to noise coupling. A 10-kΩ pull-up or pull-down resistor is recommended for flexibility; direct connection is acceptable if the input is permanently inactive.

Does the SN74HC126PWR support 5 V operation?

Yes. The SN74HC126PWR is fully specified for 5 V operation across –40°C to +85°C, with VOH ≥ 4.4 V (min) and VOL ≤ 0.33 V (max) at IOL = 6 mA, ensuring robust interfacing with TTL and 5 V CMOS loads without level translation.

What is the thermal resistance (RθJA) of the SN74HC126PWR in its TSSOP-14 package?

The SN74HC126PWR in TSSOP-14 has RθJA = 151.7°C/W under JEDEC JESD51-2 conditions. This value assumes standard 2-layer PCB with minimal copper pour; actual board layout (e.g., thermal vias, ground plane area) significantly impacts real-world junction temperature rise.

How does the 3-state output behavior of the SN74HC126PWR prevent bus contention?

When the OE input is low, the SN74HC126PWR output enters high-impedance (Z) state with leakage ≤ ±0.5 µA, effectively disconnecting the pin electrically from the bus. This allows multiple SN74HC126PWR devices or other drivers to share the same net without current conflict, provided only one device enables its output at any time.