Texas Instruments CD74HC125E

Overview

CD74HC125E 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 to 6 V supply, supports –55°C to +125°C temperature range, drives up to 10 LSTTL loads, and implements Y = A Boolean function per channel. It is used in bidirectional data bus control where output enable/disable sequencing is required.

For engineers reviewing the CD74HC125E datasheet, CD74HC125E pinout, CD74HC125E application, or CD74HC125E equivalent, key selection criteria include 3-state timing (tpd ≤ 26 ns at 6 V), input voltage thresholds (VIH = 4.2 V min at VCC = 6 V), thermal resistance (RθJA = 62.7°C/W), and PDIP-14 package compatibility with through-hole prototyping and industrial control PCBs.

Technical Context

This device integrates four independent CMOS buffer channels, each with active-low 3-state output enable (OE) and standard CMOS inputs. Each channel performs Y = A logic with balanced sourcing/sinking capability (±4 mA output drive at 4.5 V).

It uses HCMOS technology with buffered inputs, enabling clean signal replication while minimizing input loading. The 3-state outputs support high-impedance bus sharing, and its wide VCC range (2–6 V) allows interoperability with 3.3 V and 5 V logic families without level translation.

Key Specifications

Pinout & Package

CD74HC125E is housed in a 14-pin Plastic Dual In-line Package (PDIP) with 19.30 mm × 6.40 mm body size, optimized for through-hole mounting, manual soldering, and legacy industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC125E, SN74HC125N offers identical electrical and thermal performance with updated TI branding, while MC74HC125ANG provides second-source assurance with negligible impact on board-level power or timing margins.

Availability

CD74HC125E is available at Aetrix Electronics and suitable for industrial bus isolation, automotive sensor interface, and legacy system signal conditioning requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC125E 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 experience in high-reliability industrial and automotive IC design.

CD74HC125E belongs to TI's HCMOS logic family, engineered for robust noise immunity, wide supply flexibility, and extended-temperature operation in mission-critical control systems.

FAQ

What is the maximum capacitive load the CD74HC125E can drive while maintaining specified timing?

The CD74HC125E is characterized for CL ≤ 50 pF in switching specifications, with optimal performance up to 70 pF. At 6 V supply, propagation delay remains within 26 ns up to 50 pF; exceeding this may increase tpd and transition time beyond datasheet limits. For loads >70 pF, add a series resistor to limit peak output current per Absolute Maximum Ratings. The CD74HC125E datasheet specifies CL = 50 pF for all timing parameters including tpd, ten, and tdis.

Does the CD74HC125E support mixed-voltage operation between 3.3 V and 5 V logic domains?

Yes - the CD74HC125E operates from 2 V to 6 V, allowing direct connection to both 3.3 V and 5 V supplies. Its VIH threshold is 4.2 V (min) at VCC = 6 V and 3.15 V (min) at VCC = 4.5 V, ensuring reliable recognition of 3.3 V logic HIGH when powered at 5 V. The CD74HC125E also tolerates 5 V inputs when VCC = 3.3 V, provided clamp current limits are observed.

How should unused inputs and outputs be handled on the CD74HC125E?

Unused inputs must be terminated to VCC or GND - floating CMOS inputs cause undefined states and increased power consumption. A 10 kΩ pull-up or pull-down is recommended for flexibility. Unused outputs may be left unconnected (floating) since they enter high-impedance state when OE is HIGH; do not tie them directly to VCC or GND. This guidance is explicitly stated in the CD74HC125E datasheet Section 9.2.1.2 and Figure 11-1 layout example.

What is the thermal performance of the CD74HC125E in its PDIP package?

The CD74HC125E in PDIP (N) package has RθJA = 62.7°C/W, meaning junction temperature rises 62.7°C above ambient per watt of dissipated power. At max ICC = 160 µA and worst-case output loading, total power is <1 mW - resulting in negligible self-heating. This makes thermal derating unnecessary in most applications, but the CD74HC125E datasheet still mandates adherence to TJ ≤ 150°C per Absolute Maximum Ratings.

Is the CD74HC125E RoHS compliant and lead-free?

Yes - the CD74HC125E is RoHS compliant with NiPdAu (NIPDAU) lead finish, as confirmed in TI's Package Option Addendum. It meets JEDEC J-STD-020 moisture sensitivity Level-1 (unlimited floor life) and is rated for peak reflow at 260°C. The CD74HC125E part marking and packaging data confirm full compliance with EU RoHS Directive 2011/65/EU and related exemptions.