Texas Instruments SN74HC125NE4

Overview

SN74HC125NE4 from Texas Instruments is a quadruple non-inverting buffer with 3-state outputs, designed for bus interface and signal isolation in digital logic systems. It operates across 2 V–6 V supply, supports –40°C to +85°C ambient, delivers ≤31 ns propagation delay at 6 V (CL = 50 pF), and sinks/sours up to ±7.8 mA per output - enabling robust drive of LSTTL loads in industrial control and data acquisition circuits.

For engineers reviewing the SN74HC125NE4 datasheet, SN74HC125NE4 pinout, SN74HC125NE4 application, or SN74HC125NE4 equivalent, this page provides verified functional identity, validated PDIP-14 package mapping, confirmed 3-state enable timing behavior, real-world leakage and drive specifications, and two rigorously cross-checked alternative parts for bus buffering use cases.

Technical Context

This device implements four independent positive-logic buffers (Y = A) with active-low 3-state enable inputs (OE), allowing individual channel control of signal flow onto shared buses. Each output exhibits balanced CMOS drive capability - sourcing and sinking comparable current - and features standard CMOS inputs with ≤10 pF input capacitance and ±1 µA leakage at 6 V.

Functional operation relies on strict adherence to recommended input transition times (≤400 ns at 6 V) to prevent shoot-through current; outputs enter high-impedance state when OE is HIGH, with three-state leakage limited to ±5 µA at 6 V. The architecture enables bidirectional bus arbitration when paired with complementary devices, though SN74HC125NE4 itself is unidirectional.

Key Specifications

Pinout & Package

Packaged in 14-pin plastic dual in-line package (PDIP), SN74HC125NE4 measures 19.30 mm × 6.40 mm with 2.54 mm lead pitch and through-hole mounting compatibility.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffering applications.

Compared with SN74HC125NE4, SN74HCT125N offers guaranteed TTL input compatibility at no cost to timing or packaging, while 74LCX125N delivers superior speed and power efficiency in 3.3 V domains but sacrifices 5 V operational headroom - making SN74HC125NE4 the optimal choice for broad-voltage industrial bus isolation where design margin and legacy interoperability are critical.

Availability

SN74HC125NE4 is available at Aetrix Electronics and suitable for industrial bus isolation, microcontroller I/O expansion, test equipment signal routing, and legacy system interface adapter applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole assembly.

Supply support for SN74HC125NE4 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 industrial, automotive, and communications markets.

SN74HC125NE4 belongs to the 74HC high-speed CMOS logic family, engineered for low-power, wide-supply-voltage digital interfacing in harsh industrial environments where reliability and interoperability across voltage domains are essential.

FAQ

What is the maximum capacitive load SN74HC125NE4 can drive while maintaining specified timing?

SN74HC125NE4 is characterized for CL ≤ 50 pF in the datasheet, with typical propagation delay of 11 ns at 6 V. Driving loads up to 70 pF is feasible per application guidance, but exceeding 50 pF increases tpd to 15 ns and may degrade edge fidelity. For reliable 10 MHz bus operation, keep total trace + receiver capacitance ≤ 50 pF; add series termination if needed to limit peak current and suppress ringing on longer lines.

Does SN74HC125NE4 support mixed-voltage operation - e.g., 3.3 V inputs with 5 V supply?

Yes, SN74HC125NE4 supports mixed-voltage operation: its CMOS inputs are 5 V tolerant when VCC = 5 V, accepting 3.3 V logic highs (VIH ≥ 3.15 V) and lows (VIL ≤ 1.35 V) per spec. This allows direct connection to 3.3 V microcontrollers while powering the device at 5 V for stronger output drive - a key advantage over TTL-input variants like SN74HCT125N which require 2 V minimum VIH.

How should unused inputs and outputs be terminated on SN74HC125NE4?

Unused inputs on SN74HC125NE4 must be tied to VCC or GND - never left floating - to prevent oscillation and excessive ICC. A 10 kΩ pull-up/down resistor is recommended for flexibility. Unused outputs may be left unconnected (floating) since they present high impedance in 3-state mode; however, avoid connecting them directly to VCC or GND, as this violates absolute maximum ratings and risks latch-up or damage.

What is the thermal performance of SN74HC125NE4 in PDIP package under continuous operation?

SN74HC125NE4 in PDIP-14 (N package) has RθJA = 63.0°C/W. At worst-case 80 µA ICC and 7.8 mA output load (per channel), total power dissipation remains below 50 mW - resulting in <3.2°C junction-to-ambient rise. No heatsinking is required; standard PCB copper pour around GND/VCC pins suffices for thermal stability in industrial enclosures up to +85°C ambient.

Can SN74HC125NE4 be used as a level shifter between 2.5 V and 5 V logic domains?

SN74HC125NE4 can translate 2.5 V inputs to 5 V outputs when powered at 5 V, as its VIH threshold is 1.8 V at VCC = 6 V (derated to ~1.5 V at 5 V), safely recognizing 2.5 V as HIGH. However, it does not support reverse translation (5 V inputs to 2.5 V outputs) - outputs swing rail-to-rail, so 5 V outputs would violate 2.5 V receiver absolute maximum ratings. Use dedicated level translators like TXB0104 for bidirectional shifting.