Texas Instruments CD74HC125EE4

Overview

CD74HC125EE4 from Texas Instruments is a quadruple non-inverting buffer with 3-state outputs, designed for bus interface and signal enable applications in digital logic systems. It operates across 2 V to 6 V supply voltage, supports –55°C to +125°C temperature range, delivers propagation delay as low as 17 ns at 6 V, and drives up to 10 LSTTL loads - enabling robust data bus control in industrial and automotive control modules.

For engineers reviewing the CD74HC125EE4 datasheet, CD74HC125EE4 pinout, CD74HC125EE4 application, or CD74HC125EE4 equivalent, key selection criteria include its 14-pin PDIP package, active-low 3-state enable per channel, guaranteed VOH ≥ 5.48 V / VOL ≤ 0.4 V at 6 V/5.2 mA, and compatibility with HC logic families requiring fanout scalability and wide-temperature operation.

Technical Context

The CD74HC125EE4 implements four independent positive-logic buffers (Y = A), each with dedicated active-low output enable (OE) control. Its CMOS inputs exhibit high impedance and 10 pF input capacitance, while balanced 3-state outputs provide symmetrical sourcing/sinking capability up to ±35 mA per pin.

Each channel operates independently under recommended conditions: supply voltage 2–6 V, input transition time ≤400 ns at 6 V, and load capacitance ≤50 pF for specified switching performance. The device uses standard CMOS process technology with clamp diodes on all I/O pins for ESD protection per HBM ±2000 V.

Key Specifications

Pinout & Package

CD74HC125EE4 is housed in a 14-pin Plastic Dual In-line Package (PDIP-N), body size 19.30 mm × 6.40 mm, with through-hole mounting and industry-standard lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC125N and MC74HC125ANG, the CD74HC125EE4 offers identical functionality and layout compatibility but carries TI's legacy part marking and long-term industrial qualification history - making it preferred for legacy system maintenance and aerospace-grade documentation traceability.

Availability

CD74HC125EE4 is available at Aetrix Electronics and suitable for industrial bus interface, automotive sensor hub, test equipment signal routing, and legacy system upgrade adapter applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74HC125EE4 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 90 years of innovation in industrial, automotive, and communications markets.

The CD74HC125EE4 belongs to TI's 74HC high-speed CMOS logic family, engineered for low-power, wide-voltage digital interfacing in harsh-environment systems where reliability and long-term manufacturability are critical.

FAQ

What is the maximum capacitive load the CD74HC125EE4 can drive while maintaining specified timing?

The CD74HC125EE4 is characterized for CL = 50 pF in its switching specifications, with propagation delay tpd = 17 ns max at 6 V. Driving loads >50 pF increases delay and may cause ringing; TI recommends limiting total load to ≤70 pF and adding series resistors if higher capacitance is unavoidable. The CD74HC125EE4 datasheet specifies performance only up to 50 pF, so design margins should account for worst-case variation across voltage and temperature.

Can the CD74HC125EE4 operate reliably at 3.3 V supply voltage?

Yes, the CD74HC125EE4 is fully specified from 2 V to 6 V, including 3.3 V operation. At VCC = 3.3 V, VIH = 2.31 V min and VIL = 0.99 V max ensure compatibility with standard 3.3 V CMOS outputs, and VOH ≥ 3.2 V / VOL ≤ 0.33 V at 4 mA load meet typical receiver thresholds. The CD74HC125EE4 maintains full –55°C to +125°C operation at 3.3 V without derating.

How should unused inputs and outputs be handled on the CD74HC125EE4?

Unused inputs on the CD74HC125EE4 must be terminated to VCC or GND - never left floating - to prevent undefined logic states and excessive current draw. Unused outputs may be left unconnected (floating) since they enter high-impedance state when disabled. TI recommends 10-kΩ pull-up/down resistors for unused OE or A pins if default logic state is required, as specified in Section 9.2.1.2 of the CD74HC125EE4 datasheet.

Does the CD74HC125EE4 support hot insertion or live insertion into a powered backplane?

No, the CD74HC125EE4 does not support hot insertion. Its absolute maximum ratings require VCC to be established before applying input signals, and simultaneous application of inputs before VCC can forward-bias internal clamp diodes, causing latch-up or damage. For backplane applications requiring live insertion, dedicated hot-swap controllers or buffers with power-on reset and Ioff protection (e.g., SN74LVC1G125) must be used instead of the CD74HC125EE4.

What thermal considerations apply to the CD74HC125EE4 in continuous operation?

The CD74HC125EE4 in PDIP package has RθJA = 62.7°C/W. At maximum ICC = 160 µA and worst-case output loading, self-heating is negligible; however, junction temperature must remain ≤150°C. With ambient at +125°C, the device can dissipate only ~0.4 W before exceeding TJ(max). Layout best practices - including short traces, ground flooding, and local 0.1 µF bypassing - are essential to maintain thermal stability, especially when multiple channels switch simultaneously. The CD74HC125EE4 thermal data is validated per JEDEC JESD51 standards.