Texas Instruments CD74HCT125MT

Overview

CD74HCT125MT from Texas Instruments is a quadruple 3-state buffer IC used for digital signal routing and bus isolation in logic systems. It features four independent channels, LSTTL- and CMOS-compatible inputs (VIL(max) = 0.8 V, VIH(min) = 2 V), 4.5–5.5 V supply operation, –55°C to +125°C temperature range, and supports fanout of up to 10 LSTTL loads.

For engineers reviewing the CD74HCT125MT datasheet, CD74HCT125MT pinout, CD74HCT125MT application, or CD74HCT125MT equivalent, key selection considerations include its 14-pin SOIC package, active-low 3-state enable per channel, propagation delay of 10 ns (typical at 5 V, CL = 15 pF), output drive capability (±4 mA), and thermal performance (RθJA = 138.7°C/W).

Technical Context

The CD74HCT125MT implements four identical non-inverting buffers, each with an independent active-low 3-state output enable (OE). Each channel performs Y = A in positive logic, enabling/disabling data flow without inversion. Input structure combines TTL-level voltage thresholds with CMOS input leakage (≤1 µA), ensuring compatibility with both legacy bipolar and modern low-power logic families.

Its balanced CMOS 3-state outputs source and sink comparable current (VOH ≥ 3.98 V at IOH = –4 mA; VOL ≤ 0.4 V at IOL = 4 mA), supporting bidirectional bus control. The device operates across military-grade temperature extremes and maintains specified switching characteristics (tpd, ten, tdis, tt) under load conditions up to 50 pF.

Key Specifications

Pinout & Package

CD74HCT125MT is supplied in a 14-pin SOIC (D) package measuring 8.65 mm × 6 mm (including pins), with body size 8.65 mm × 3.9 mm. Pinout is identical to industry-standard 14-pin SOIC logic devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HCT125MT, SN74HCT125DR offers assured long-term availability and updated thermal metrics (RθJA = 123.2°C/W), while MC74HCT125AD provides cross-manufacturer qualification for supply chain resilience-both retain identical timing, drive strength, and interface compatibility.

Availability

CD74HCT125MT is available at Aetrix Electronics and suitable for industrial bus isolation, microcontroller peripheral expansion, legacy system interface adaptation, and aerospace data multiplexing requiring stable component supply across extended temperature ranges.

Supply support for CD74HCT125MT 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 high-reliability components.

The CD74HCT125MT belongs to TI's HCT logic family, designed specifically for TTL-compatible CMOS operation in harsh environments-targeting industrial automation, defense systems, and automotive subsystems demanding wide temperature range and robust ESD immunity.

FAQ

What is the operating voltage range for CD74HCT125MT?

The CD74HCT125MT operates from 4.5 V to 5.5 V. This range ensures compatibility with standard 5 V logic systems while accommodating typical power supply tolerances. Operation outside this range may cause unreliable switching or damage, as defined in the absolute maximum ratings (VCC = –0.5 V to 7 V). Always verify supply stability under load, especially in high-temperature environments where ICC increases.

Does CD74HCT125MT support true 3-state outputs?

Yes, CD74HCT125MT provides true CMOS 3-state outputs with high-impedance (Z) states controlled by active-low OE inputs. When OE is high, the output enters high-impedance mode with leakage current ≤ ±10 µA (at 5.5 V, –55°C to +125°C), allowing safe bus sharing. This behavior is confirmed in the function table and electrical characteristics section of the datasheet, and is essential for applications like bidirectional data bus control.

What is the maximum capacitive load CD74HCT125MT can drive reliably?

CD74HCT125MT is characterized for loads up to 50 pF (with 15 pF used for typical timing specs), and the datasheet recommends keeping total output capacitance ≤ 70 pF for optimal performance. Exceeding this may increase propagation delay and cause ringing due to fast edge rates. For heavier loads, add a series resistor to limit peak output current to ≤ ±4 mA and avoid violating absolute maximum ratings.

Is CD74HCT125MT suitable for automotive applications?

CD74HCT125MT is rated for –55°C to +125°C operation and meets HBM ESD requirements (±2000 V), making it suitable for under-hood and chassis-mounted automotive subsystems. However, it is not AEC-Q100 qualified. For production automotive ECUs, TI recommends the automotive-grade SN74HCT125QPWRQ1, which undergoes full AEC-Q100 stress testing and has extended reliability validation beyond the specifications of CD74HCT125MT.

How should unused inputs and outputs be handled on CD74HCT125MT?

Unused inputs on CD74HCT125MT must be terminated to VCC or GND-never left floating-to prevent undefined logic states and increased ICC. A 10 kΩ pull-up or pull-down resistor is recommended for flexibility. Unused outputs may be left unconnected (floating), but must never be tied directly to VCC or GND, as this risks exceeding output current limits and damaging the device. These guidelines are specified in Section 8.2.1 of the official datasheet.