Texas Instruments SN74HCS125DYYR

Overview

SN74HCS125DYYR from Texas Instruments is a quadruple non-inverting buffer IC with 3-state outputs and Schmitt-trigger inputs, operating across 2V–6V supply. It delivers ±7.8mA output drive at 6V, features 100nA typical ICC, supports –40°C to +125°C ambient operation, and enables signal gating in bus isolation or switch debouncing circuits.

For engineers reviewing the SN74HCS125DYYR datasheet, SN74HCS125DYYR pinout, SN74HCS125DYYR application, or SN74HCS125DYYR equivalent, key selection criteria include Schmitt-trigger noise immunity, 3-state bus control capability, low quiescent current, and SOT-23-THIN (14-pin) package compatibility with high-density PCB layouts.

Technical Context

This device implements four independent Y = A positive-logic buffers, each with active-low 3-state enable (OE) control. The Schmitt-trigger input architecture provides 0.55V–1.49V hysteresis (ΔVT), enabling reliable operation with slow-rising or noisy signals without external conditioning.

Each channel's CMOS push-pull output supports balanced sourcing/sinking up to ±7.8mA at 6V, while maintaining rail-to-rail VOH/VOL performance (e.g., VOL ≤ 0.33V at IOL = 7.8mA, 6V). Propagation delay is as low as 5ns at 6V, with enable/disable times under 9ns.

Key Specifications

Pinout & Package

SOT-23-THIN (14-pin) package: 2.00mm × 4.20mm footprint, thin-profile design optimized for space-constrained portable and wearable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS125DR and SN74LVC125AQPWRQ1, the SN74HCS125DYYR uniquely combines ultra-compact SOT-23-THIN packaging, industry-leading Schmitt-trigger hysteresis (≥0.55V), and nanoscale quiescent current-making it optimal for space- and power-constrained IoT edge nodes where signal integrity trumps automotive certification.

Availability

SN74HCS125DYYR is available at Aetrix Electronics and suitable for industrial switch debouncing, LED indicator control, bus signal isolation, and noisy sensor interface applications requiring stable component supply across extended temperature ranges.

Supply support for SN74HCS125DYYR 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, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The SN74HCS125DYYR belongs to TI's HCS logic family, designed specifically for low-power, noise-immune digital interfacing in harsh environments-emphasizing Schmitt-trigger robustness, wide-VCC flexibility, and extended temperature resilience.

FAQ

What is the maximum capacitive load the SN74HCS125DYYR can drive while meeting datasheet timing specifications?

The SN74HCS125DYYR is specified to drive loads ≤50pF while maintaining guaranteed propagation delay and transition time performance. Exceeding this capacitance increases tpd and tt, potentially violating setup/hold margins in high-speed interfaces. For larger loads, add series termination or use a driver with higher Cpd rating. The SN74HCS125DYYR's 10pF typical power-dissipation capacitance reflects its optimized balance of speed and low power.

Does the SN74HCS125DYYR require external pull-up or pull-down resistors on unused inputs?

Yes - unused inputs on the SN74HCS125DYYR must be terminated to either VCC or GND to prevent floating states that cause excessive current draw and logic instability. A 10kΩ resistor is recommended due to its compatibility with the device's ±100nA input leakage and minimal impact on signal rise/fall times. Leaving inputs unconnected violates TI's layout guidelines and risks undefined operation.

Can the SN74HCS125DYYR outputs be paralleled for higher current drive?

Yes - two or more channels of the SN74HCS125DYYR with identical inputs and enables can be wired in parallel to increase total output current capacity beyond ±7.8mA. This configuration maintains matched switching behavior and avoids shoot-through because all outputs share the same A and OE signals. Ensure trace lengths and loading are symmetrical to preserve timing alignment across paralleled channels.

What is the absolute maximum supply voltage rating for the SN74HCS125DYYR, and what happens if exceeded?

The SN74HCS125DYYR has an absolute maximum VCC rating of 7V. Operation above this voltage risks permanent damage due to junction breakdown or oxide stress, even for brief durations. TI explicitly states that exceeding absolute maximum ratings may cause irreversible device failure - no functional operation is guaranteed beyond 7V, and reliability degradation begins immediately upon violation. Always maintain VCC within 2V–6V recommended range.

How does the Schmitt-trigger input of the SN74HCS125DYYR improve noise immunity compared to standard CMOS inputs?

The SN74HCS125DYYR's Schmitt-trigger inputs provide hysteresis (ΔVT ≥ 0.55V at 2V), meaning the threshold for detecting a rising edge (VT+ ≈ 1.18V) differs significantly from that for a falling edge (VT− ≈ 0.61V). This gap prevents oscillation when input signals cross slowly or contain noise spikes smaller than ΔVT - unlike standard CMOS inputs, which have a single threshold and may chatter on noisy edges. As a result, the SN74HCS125DYYR reliably captures clean logic transitions from switches, sensors, or long cables without additional filtering.