onsemi MC74VHCT240ADWRG

Overview

MC74VHCT240ADWRG from onsemi is an octal inverting 3-state buffer/line driver IC designed for TTL-level input compatibility and CMOS-level output drive. It operates at 4.5–5.5 V, features 8 ns typical propagation delay at 5 V, supports ±8 mA output drive, and is housed in a 20-pin SOIC-Wide (SO-20W) package. It serves as a bidirectional bus interface in industrial control backplanes.

For engineers reviewing the MC74VHCT240ADWRG datasheet, pinout, applications, or equivalent options, key selection criteria include its TTL-compatible inputs, 3-state outputs with independent enable controls per group, rail-to-rail CMOS output swing, and guaranteed AC/DC performance across industrial temperature range (−40°C to +85°C).

Technical Context

This device integrates two independent 4-bit inverting buffer groups, each with separate active-low output-enable (1OE, 2OE) controls. Each output exhibits high-impedance state when its OE is high, enabling shared-bus contention-free operation.

Input thresholds are TTL-compatible (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), while outputs swing fully to V_CC or GND with CMOS drive strength. Propagation delays are symmetric (t_PLH ≈ t_PHL ≈ 8 ns at V_CC = 5 V, C_L = 50 pF), supporting reliable timing in synchronous bus systems.

Key Specifications

Pinout & Package

MC74VHCT240ADWRG is packaged in a 20-pin SOIC-Wide (SO-20W) body with 0.600-inch width and 1.27 mm pitch. The package meets JEDEC MS-013AC and is RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT240N and 74VHC240M, MC74VHCT240ADWRG uniquely combines SOIC-W packaging, 8 ns speed, and guaranteed TTL input compatibility-making it optimal for new industrial designs requiring robust surface-mount bus interfaces with legacy interoperability.

Availability

MC74VHCT240ADWRG is available at Aetrix Electronics and suitable for industrial PLC backplanes, automated test equipment signal routing, and medical diagnostic instrument data buses requiring stable component supply and long-term lifecycle support.

Supply support for MC74VHCT240ADWRG 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 is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC74VHCT240ADWRG belongs to onsemi's VHCT logic family, engineered specifically for high-speed, low-power 5 V TTL-to-CMOS interfacing in mission-critical industrial and medical systems.

FAQ

What is the maximum operating frequency supported by MC74VHCT240ADWRG?

The MC74VHCT240ADWRG does not specify a maximum clock frequency in its datasheet because it is a combinational logic device-not a clocked sequential element. Its usable data rate is determined by propagation delay (8 ns typical) and system timing margins. For clean 100 MHz bus operation, designers must account for setup/hold times of downstream latches and PCB trace delays; the MC74VHCT240ADWRG itself supports such rates when loaded with ≤50 pF and driven within its 4.5–5.5 V supply range.

Does MC74VHCT240ADWRG support hot-swap operation on shared buses?

Yes, MC74VHCT240ADWRG supports hot-swap operation via its dual active-low 3-state enable inputs (1OE and 2OE). When either enable is held high, its corresponding 4-bit output group enters high-impedance state, eliminating bus contention during live insertion or removal of peripheral modules. This capability is validated across the full −40°C to +85°C range and is critical for modular PLC and ATE architectures using the MC74VHCT240ADWRG.

Is MC74VHCT240ADWRG pin-compatible with standard 74HCT240 devices?

Yes, MC74VHCT240ADWRG is pin-compatible with industry-standard 74HCT240 devices in SO-20W packages, including identical pin numbering, function mapping, and power/ground locations. However, its VHCT variant delivers faster propagation delay (8 ns vs. 12–15 ns) and tighter AC specifications while maintaining full DC compatibility-making MC74VHCT240ADWRG a direct performance upgrade without layout changes.

What is the recommended decoupling for MC74VHCT240ADWRG?

Each MC74VHCT240ADWRG should be decoupled with a 0.1 µF X7R ceramic capacitor placed within 3 mm of its V_CC (pin 20) and GND (pin 19) pins. For systems with multiple devices or high switching activity, add a bulk 4.7 µF tantalum or aluminum electrolytic capacitor per 5–10 ICs on the same 5 V rail. This decoupling strategy suppresses simultaneous switching noise and maintains stable V_CC during the ±8 mA output transitions inherent to MC74VHCT240ADWRG operation.

Can MC74VHCT240ADWRG drive a 50 Ω transmission line directly?

No, MC74VHCT240ADWRG is not designed for direct 50 Ω line driving. Its ±8 mA output drive corresponds to ~625 Ω effective impedance at 5 V, optimized for 50 pF capacitive loads (e.g., PCB traces + TTL inputs), not 50 Ω resistive termination. Driving 50 Ω lines requires external series termination or dedicated line drivers. Using MC74VHCT240ADWRG unbuffered into 50 Ω will cause excessive current draw, signal distortion, and potential output stage damage.