onsemi MM74HCT240WM

Overview

MM74HCT240WM from onsemi is an inverting octal 3-STATE buffer IC designed for TTL-to-CMOS bus interfacing, featuring dual active-low enables (1G, 2G), 14 ns typical propagation delay at 5 V, ±6 mA output drive per pin, and SOIC-20 WB (case 751D−05) packaging. It operates across −55 °C to +125 °C and supports high-capacitance bus driving in industrial control backplanes.

For engineers reviewing the MM74HCT240WM datasheet, pinout, applications, or equivalent options, key selection criteria include inverting logic polarity, dual independent 4-bit enable control, 3-STATE output compatibility with shared data buses, and Pb-free SOIC-20 WB footprint compliance.

Technical Context

The MM74HCT240WM implements two independent 4-bit inverting buffer sections, each controlled by its own active-low enable (1G for Y1–Y4, 2G for Y5–Y8). Inputs are TTL-compatible (VIH = 2.0 V min, VIL = 0.8 V max) and internally clamped to VCC and GND.

Its 3-STATE outputs support bidirectional bus architectures with guaranteed high-impedance isolation (IOZ ≤ ±10 µA over full temperature range) and fast disable timing (tPHZ/tPLZ ≤ 38 ns at CL = 50 pF, −55 °C to +125 °C). Quiescent ICC is limited to 160 µA max under static conditions.

Key Specifications

Pinout & Package

MM74HCT240WM is housed in a Pb-free SOIC-20 WB package (case 751D−05), 12.8 mm × 7.5 mm body, 1.27 mm pitch, with 1.0 mm nominal height and gull-wing leads. Pin 1 marked by notch or bevel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar inverting octal 3-STATE buffer applications.

Compared with SN74HCT240N and 74VHC240N, MM74HCT240WM uniquely combines full −55 °C to +125 °C qualification, guaranteed TTL input compatibility, and SOIC-20 WB pinout - making it the sole option for ruggedized 5 V bus interface in automotive and industrial control where ambient extremes and legacy interoperability are mandatory.

Availability

MM74HCT240WM is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, and automated test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MM74HCT240WM 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, logic, and sensing solutions for automotive, industrial, and cloud infrastructure markets.

The MM74HCT240WM belongs to onsemi's HCT logic family - engineered specifically for TTL-to-CMOS bridging in harsh-environment 5 V systems, emphasizing robustness, interoperability, and drop-in replaceability for legacy LS-TTL designs.

FAQ

What is the operating temperature range supported by the MM74HCT240WM?

The MM74HCT240WM is fully specified from −55 °C to +125 °C, meeting extended industrial and automotive under-hood requirements. This range is validated across all DC and AC electrical parameters including propagation delay, output drive, and 3-STATE leakage - unlike commercial-grade alternatives that only guarantee −40 °C to +85 °C operation. The MM74HCT240WM maintains reliable performance even during cold-start or sustained high-temperature operation.

Is the MM74HCT240WM pin-compatible with the obsolete 74LS240?

Yes, the MM74HCT240WM uses the same SOIC-20 WB footprint and identical pinout as the 74LS240, including matching enable (1G/2G), input (1A–4A, 2A–2D), and output (1Y–4Y, 2Y–2D) assignments. No PCB redesign is required. The MM74HCT240WM also replicates the truth table and electrical interface behavior - making it a true drop-in replacement with significantly lower power consumption and improved noise immunity.

Does the MM74HCT240WM support 3.3 V logic inputs?

No, the MM74HCT240WM is designed exclusively for 5 V TTL-compatible operation. Its input thresholds are VIH ≥ 2.0 V and VIL ≤ 0.8 V - optimized for 5 V rail systems. Applying 3.3 V logic signals may result in marginal or undefined switching behavior, especially over temperature. For mixed-voltage designs, level-shifting circuitry or a 3.3 V–tolerant alternative like 74LVC240 should be used instead of relying on the MM74HCT240WM.

What is the maximum capacitive load the MM74HCT240WM can drive reliably?

The MM74HCT240WM is characterized up to CL = 150 pF in AC specifications, with propagation delay increasing from 20 ns (CL = 50 pF) to 42 ns (CL = 150 pF) at −55 °C to +125 °C. Its ±6 mA output drive ensures stable edge rates into typical PCB trace and connector capacitances found in backplane and cable-driven applications. For loads exceeding 150 pF, derating or buffering with additional stages is recommended to maintain timing margins.

How does the dual-enable architecture of the MM74HCT240WM improve system design?

The MM74HCT240WM's separate 1G and 2G enables allow independent control of two 4-bit inverting channels - enabling time-division multiplexing, isolated bus segments, or hierarchical enable trees without external logic. This reduces gate count and routing complexity compared to single-enable octal buffers. In practice, this lets designers partition data paths (e.g., sensor vs. actuator groups) and minimize simultaneous switching noise on shared VCC/GND rails - directly improving signal integrity in dense control modules.