Texas Instruments SN74HCS126PWR

Overview

SN74HCS126PWR from Texas Instruments is a quadruple non-inverting buffer with 3-state outputs and Schmitt-trigger inputs, designed for signal conditioning in noisy or slow-transition environments. It operates from 2 V to 6 V, delivers ±7.8-mA output drive at 6 V, supports –40°C to +125°C ambient temperature, and implements Y = A logic per channel. It is used to enable/disable digital buses, debounce mechanical switches, and interface with unreliable input sources.

For engineers reviewing the SN74HCS126PWR datasheet, SN74HCS126PWR pinout, SN74HCS126PWR application, or SN74HCS126PWR equivalent, key selection considerations include its Schmitt-trigger hysteresis (min 0.2 V at 2 V), low ICC (100 nA typical), 3-state control timing (enable/disable <14 ns at 6 V), and TSSOP-14 package compatibility with high-density PCB layouts.

Technical Context

This device integrates four independent CMOS buffer channels, each with active-high 3-state enable (OE) and Schmitt-trigger input architecture providing hysteresis (ΔVT = 0.2–1.6 V depending on VCC). The inputs tolerate slow edges and noise without false triggering, while balanced CMOS outputs support bidirectional current sourcing/sinking up to ±7.8 mA at 6 V.

Functional operation follows a simple truth table: when OE is low, output Y enters high-impedance state (Z); when OE is high, Y mirrors A. Propagation delay is 7–50 ns across 2–6 V supply, with transition time as low as 4 ns at 6 V - enabling reliable use in mixed-voltage 3.3 V/5 V systems and industrial control interfaces.

Key Specifications

Pinout & Package

TSSOP-14 package (5.00 mm × 4.40 mm body size), 0.65 mm pitch, thin-profile surface-mount construction suitable for automated assembly and space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS126PWR, SN74HCS125PWR offers functional equivalence with inverted logic - ideal for complementary signal paths - while SN74LV126APWR trades hysteresis and ultra-low ICC for broader logic-family compatibility at the expense of noise resilience.

Availability

SN74HCS126PWR is available at Aetrix Electronics and suitable for industrial switch debouncing, automotive sensor conditioning, and low-power IoT node signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74HCS126PWR 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 delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN74HCS126PWR belongs to TI's HCS logic family - designed specifically for robust, low-power, noise-immune digital interfacing in harsh environments where reliability outweighs raw speed.

FAQ

What is the maximum capacitive load SN74HCS126PWR can drive while maintaining specified timing?

The SN74HCS126PWR is characterized for loads ≤50 pF across all operating conditions. Driving larger capacitances increases propagation delay and transition time - for example, a 100 pF load may extend tpd by ~2× at 6 V. For reliable timing compliance, keep total node capacitance (trace + receiver input + probe) at or below 50 pF, or validate performance empirically with worst-case VCC and temperature.

Does SN74HCS126PWR require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of SN74HCS126PWR must be terminated to either VCC or GND to prevent floating states that cause increased ICC and potential logic instability. A 10 kΩ resistor is commonly used; direct connection is acceptable if the controlling node is static. This requirement applies even though inputs have Schmitt-trigger architecture - floating pins remain electrically undefined.

Can SN74HCS126PWR outputs be paralleled for higher current drive?

Yes - two or more channels of SN74HCS126PWR with identical inputs and enables can be wired in parallel to increase sink/source capability beyond ±7.8 mA. Ensure matched trace lengths and simultaneous enable control to avoid shoot-through. Do not parallel outputs driven by different signals or timing domains, as this risks contention and device damage.

What is the minimum hysteresis voltage (ΔVT) of SN74HCS126PWR at 3.3 V supply?

At VCC = 3.3 V, the minimum hysteresis voltage ΔVT for SN74HCS126PWR is 0.4 V (per Electrical Characteristics table, 6.5 section). This value ensures reliable rejection of noise spikes up to ±200 mV peak-to-peak on input signals - sufficient for most industrial switch and potentiometer applications without additional filtering.

Is SN74HCS126PWR pin-compatible with older 74HC126 variants?

No - SN74HCS126PWR uses the same TSSOP-14 pinout as SN74HC126PWR, but differs electrically: it features Schmitt-trigger inputs (vs. standard CMOS), lower ICC (100 nA vs. ~2 µA), and enhanced ESD ratings (HBM ±4000 V). While footprint-compatible, substituting it for HC-series requires verifying system-level noise immunity and power budget impact.