Texas Instruments CD74HCT02M

Overview

CD74HCT02M from Texas Instruments is a quadruple 2-input positive-NOR gate IC in SOIC-14 package, performing Y = A + B logic in positive logic with buffered CMOS inputs and push-pull outputs. It operates from 4.5 V to 5.5 V, supports –55°C to +125°C industrial/military temperature range, delivers 4 mA output drive at 5 V, and is used in tamper-detect latches and S-R latch circuits.

For engineers reviewing the CD74HCT02M datasheet, CD74HCT02M pinout, CD74HCT02M application, or CD74HCT02M equivalent, key selection criteria include its TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max), propagation delay of 18 ns typical at 5 V/50 pF, fanout capability of 10 LSTTL loads, and guaranteed operation across extended temperature extremes without derating.

Technical Context

This device implements four independent NOR gates using HCT (High-Speed CMOS with TTL-compatible inputs) process technology. Its input structure matches TTL voltage thresholds while retaining CMOS power efficiency, enabling direct interface with legacy 74LS logic without level shifters. Each gate features balanced push-pull outputs capable of sourcing/sinking ±4 mA at 5 V.

The CD74HCT02M uses standard CMOS input protection with clamp diodes and exhibits low static current (ICC ≤ 20 µA at 6 V), making it suitable for battery-backed or low-power monitoring functions. Its propagation delay (tpd = 15–23 ns) and transition time (tt = 13–19 ns) are specified over full temperature and supply ranges, ensuring timing predictability in safety-critical control paths.

Key Specifications

Pinout & Package

CD74HCT02M is housed in a 14-pin SOIC (D) package measuring 8.65 mm × 3.90 mm, with standard 1.27 mm pitch and gull-wing leads compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NOR gate applications.

Compared with SN74HCT02DR and MC74VHC02DT, the CD74HCT02M uniquely balances military-grade temperature resilience, TTL interoperability, and proven field reliability in safety-critical latch and alarm functions - making it the preferred choice where environmental robustness and backward compatibility are non-negotiable.

Availability

CD74HCT02M is available at Aetrix Electronics and suitable for alarm/tamper detection, S-R latch implementation, redundant power monitoring, hardware reset arbitration, and industrial control logic requiring stable component supply across extended temperature ranges.

Supply support for CD74HCT02M 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The CD74HCT02M belongs to TI's legacy HCT logic family, engineered specifically for seamless migration from bipolar TTL systems while maintaining CMOS power advantages and extended temperature performance.

FAQ

What is the recommended operating voltage range for CD74HCT02M?

The CD74HCT02M is specified for 4.5 V to 5.5 V operation. While absolute maximum ratings allow up to 7 V, sustained operation outside the recommended range risks timing violations, increased ICC, and reduced noise margins. At 4.5 V, VIH remains ≥2.0 V and VOL stays ≤0.4 V, ensuring compatibility with downstream 74LS inputs. The CD74HCT02M must not be operated below 4.5 V if interfacing with standard TTL loads.

Can CD74HCT02M replace 74LS02 in existing designs without modification?

Yes - the CD74HCT02M is designed as a direct functional and pin-compatible replacement for 74LS02. Its TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max), identical SOIC-14 footprint, and matching pinout allow drop-in substitution. Output drive strength (±4 mA) meets or exceeds 74LS02 specifications, and propagation delay (18 ns typical) is comparable. No PCB changes or schematic updates are required for most 74LS02 applications.

How should unused inputs on CD74HCT02M be terminated?

All unused inputs on CD74HCT02M must be tied to a valid logic level - either VCC or GND - to prevent floating states that cause excessive current draw, oscillation, or undefined outputs. For active-low NOR functionality, tying an unused input to VCC forces the corresponding output LOW; tying to GND enables the gate to respond to the other input. A 10-kΩ pull-up or pull-down resistor is acceptable if dynamic switching is anticipated, but direct connection is preferred for static termination.

What is the maximum capacitive load CD74HCT02M can drive while meeting datasheet timing specs?

The CD74HCT02M is characterized for CL = 50 pF in switching specifications - propagation delay (tpd = 18 ns) and transition time (tt = 16 ns) are guaranteed only up to this load. Driving >50 pF increases tpd nonlinearly and may violate setup/hold times in synchronous systems. For loads exceeding 50 pF, add a series resistor (22–100 Ω) near the output to dampen ringing, or use a buffer stage. The CD74HCT02M itself does not require external termination for 50 pF or less.

Does CD74HCT02M support operation at –55°C, and what design considerations apply?

Yes - the CD74HCT02M is fully specified from –55°C to +125°C per MIL-PRF-38535 requirements. At –55°C, propagation delay increases to 27 ns (max), and output drive drops to ±3.2 mA (min), but all logic thresholds and DC parameters remain valid. Designers must ensure decoupling capacitors (e.g., X7R ceramics) retain capacitance at low temperature, and avoid electrolytics in the power path. The CD74HCT02M's guaranteed performance across this range eliminates need for thermal derating in arctic or space-constrained military platforms.