Texas Instruments SN74HC125NSRE4

Overview

SN74HC125NSRE4 from Texas Instruments is a quadruple 3-state buffer IC used for digital signal enablement and bus isolation in logic-level translation circuits. It features four independent non-inverting buffers (Y = A), 2 V to 6 V supply operation, –40°C to +85°C temperature range, and CMOS-compatible input/output characteristics. It is commonly deployed in microcontroller I/O expansion and bidirectional data bus control.

For engineers reviewing the SN74HC125NSRE4 datasheet, SN74HC125NSRE4 pinout, SN74HC125NSRE4 application, or SN74HC125NSRE4 equivalent, this page delivers verified functional identity, SO package mapping, 14-pin terminal roles, propagation delay (11–31 ns at 6 V), 3-state leakage (±0.5 µA), and two validated alternative parts with documented functional and application differences.

Technical Context

This device implements four independent CMOS buffer gates, each with active-low 3-state output control (OE). Each channel performs Y = A in positive logic, with balanced sourcing/sinking capability up to ±7.8 mA at 6 V. Inputs are standard high-impedance CMOS with ≤10 pF capacitance and ±1 µA leakage.

Operation requires strict adherence to recommended conditions: supply voltage 2–6 V, input transition time ≤400 ns (at 6 V), and load capacitance ≤150 pF. The 3-state outputs enter high-impedance when OE is HIGH, exhibiting ≤±5 µA leakage current and no DC path to VCC or GND.

Key Specifications

Pinout & Package

The SN74HC125NSRE4 is supplied in a 14-pin SO (Small Outline) package with nominal body size 10.20 mm × 5.30 mm, gull-wing leads, and RoHS-compliant NiPdAu finish. It is rated MSL Level-1 with unlimited reflow profile.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC125NSRE4, SN74HC244N offers double channel count but requires PCB redesign for 20-pin footprint, while 74LVC125APW delivers superior speed at 3.3 V yet sacrifices 6 V operation and 5 V input tolerance-making SN74HC125NSRE4 optimal for industrial 5 V systems needing proven reliability and wide supply margin.

Availability

SN74HC125NSRE4 is available at Aetrix Electronics and suitable for microcontroller I/O expansion, parallel data bus isolation, level translation interface, and test access & JTAG signal multiplexing requiring stable component supply across industrial temperature ranges and long-lifecycle programs.

Supply support for SN74HC125NSRE4 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 heritage in high-reliability logic families.

The SN74HC125NSRE4 belongs to the 74HC high-speed CMOS logic series, designed specifically for robust, low-power digital interfacing in industrial, automotive, and communications equipment where noise immunity and wide voltage operation are critical.

FAQ

What is the function of the OE pins on the SN74HC125NSRE4?

The SN74HC125NSRE4 has four active-low Output Enable (OE) pins-pins 1, 4, 10, and 13-one per buffer channel. When an OE pin is LOW, its corresponding buffer passes the input (A) to the output (Y); when HIGH, that output enters high-impedance (3-state) mode. This allows independent control of each of the four channels, making SN74HC125NSRE4 ideal for selective bus gating or multi-peripheral sharing.

Can SN74HC125NSRE4 operate at 3.3 V and interface with 5 V logic?

Yes, SN74HC125NSRE4 operates reliably from 2 V to 6 V, including 3.3 V and 5 V supplies. Its inputs are 5 V tolerant up to VCC + 0.5 V (per Absolute Maximum Ratings), so a 3.3 V-powered SN74HC125NSRE4 can safely accept 5 V input signals. Outputs swing rail-to-rail, meaning SN74HC125NSRE4 driven from 5 V will deliver true 5 V logic levels-enabling seamless bidirectional interfacing without external level shifters.

What is the maximum capacitive load SN74HC125NSRE4 can drive while maintaining specified timing?

Per TI's SCLS104F datasheet, SN74HC125NSRE4 is characterized for CL = 50 pF and CL = 150 pF loads. At 6 V supply, propagation delay remains within spec (max 31 ns) up to 150 pF. For optimal signal integrity and minimal ringing, TI recommends limiting load capacitance to ≤70 pF in production designs-achievable via short PCB traces and avoiding stubs. Exceeding 150 pF may degrade timing margins and increase switching noise.

How should unused inputs and outputs be handled on SN74HC125NSRE4?

Unused inputs on SN74HC125NSRE4 must be terminated to a defined logic level-either VCC or GND-to prevent floating nodes, oscillation, and excess current draw. A 10-kΩ pull-up or pull-down resistor is typical. Unused outputs may be left unconnected (floating), as the 3-state architecture inherently isolates them when OE is HIGH. Never tie outputs directly to VCC or GND, as this risks damaging the output stage during active drive.

Does SN74HC125NSRE4 require decoupling capacitors, and if so, what value?

Yes, SN74HC125NSRE4 requires local decoupling. TI specifies a 0.1 µF ceramic capacitor placed as close as possible between VCC (pin 14) and GND (pin 7), with low-inductance routing. This suppresses supply noise generated during output switching and prevents false triggering or latch-up. For noisy environments, paralleling a 1 µF capacitor is acceptable-but the 0.1 µF unit is mandatory and must be physically adjacent to the SN74HC125NSRE4 package.