onsemi 74LVTH240MSAX

Overview

74LVTH240MSAX from Fairchild Semiconductor is an inverting octal buffer/line driver with 3-STATE outputs, designed for memory address and clock driving in 3.3V systems interfacing to 5V TTL buses. It features bushold inputs (eliminating external pull-ups), ±32mA/64mA drive strength, and operates from 2.7V to 3.6V across –40°C to +85°C.

For engineers reviewing the 74LVTH240MSAX datasheet, pinout, applications, or equivalent options, key selection criteria include bushold input support, 20-pin SSOP package compatibility, 3.3V–5V mixed-voltage bus interface capability, and high-current 3-STATE output drive for dense PCB layouts.

Technical Context

The 74LVTH240MSAX implements dual 4-bit inverting buffers with independent 3-STATE control via OE1 and OE2 pins, enabling selective bus isolation. Its BiCMOS fabrication delivers ABT-class speed (tPLH/tPHL ≤ 4.6 ns at 3.3V) while maintaining low static current (ICCZ = 0.19 mA).

Bushold circuitry on all eight data inputs (I0–I7) actively maintains logic state without external biasing-critical for floating or unterminated inputs in hot-swap and partial-power-down scenarios. Power-up/down high-impedance behavior prevents bus glitches during supply sequencing.

Key Specifications

Pinout & Package

74LVTH240MSAX is housed in a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, 5.3mm wide, with 0.65mm lead pitch and gull-wing terminations for surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC240APWR and 74ALVT240MTCX, the 74LVTH240MSAX uniquely combines bushold, 5V-tolerant inputs, and ±32mA/64mA drive in a single 3.3V-buffer solution-making it optimal for mixed-voltage, high-reliability bus interfaces where input floating and hot-swap robustness are mandatory.

Availability

74LVTH240MSAX is available at Aetrix Electronics and suitable for memory address buffering, clock distribution networks, PCI bus interfacing, and industrial control backplane drivers requiring stable component supply and long-term lifecycle support.

Supply support for 74LVTH240MSAX 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

Fairchild Semiconductor was a U.S.-based designer and manufacturer of analog and mixed-signal semiconductors, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and computing infrastructure.

The 74LVTH240MSAX belongs to Fairchild's LVT/H series of low-voltage BiCMOS buffers, engineered specifically for high-density 3.3V-to-5V bus interfacing with enhanced robustness for live insertion and mixed-supply environments.

FAQ

What is the function of the bushold feature in the 74LVTH240MSAX?

The bushold feature in the 74LVTH240MSAX actively retains the last valid logic state on each data input (I0–I7) without external pull-up or pull-down resistors. This eliminates BOM components and prevents floating-input-induced noise susceptibility-especially critical during power-up, hot-swap, or partial system shutdown. The 74LVTH240MSAX uses ±75µA bushold drive at 3.0V to maintain stable logic levels under typical board leakage conditions.

Does the 74LVTH240MSAX support 5V logic inputs while operating at 3.3V VCC?

Yes, the 74LVTH240MSAX supports DC input voltages up to 5.5V on all data and enable pins while powered from 2.7V–3.6V VCC. This 5V-tolerant input capability allows direct interfacing with legacy 5V TTL systems without level-shifting circuitry-enabling clean integration into mixed-voltage designs such as 3.3V CPUs driving 5V peripherals. Input thresholds (VIH = 2.0V, VIL = 0.8V) ensure reliable recognition of both 3.3V and 5V logic levels.

What is the maximum output drive capability of the 74LVTH240MSAX?

The 74LVTH240MSAX provides asymmetric output drive: –32mA source current (IOH) and +64mA sink current (IOL) per output under recommended operating conditions. This high sink capability enables direct driving of multiple 5V TTL inputs or moderate capacitive loads (e.g., 50pF traces), while the –32mA sourcing supports clean HIGH-level signaling into lightly loaded CMOS targets. Output voltage limits (VOH ≥ VCC–0.2V, VOL ≤ 0.55V at 64mA) are guaranteed across –40°C to +85°C.

How does the 74LVTH240MSAX handle power-up and power-down sequencing?

The 74LVTH240MSAX enters a high-impedance state on all outputs during power-up and power-down transitions, preventing bus contention and signal glitches that could corrupt data or damage downstream devices. This behavior is intrinsic to its BiCMOS design and requires no external control-ensuring safe operation in multi-rail systems where VCC ramps independently of other supplies. The 74LVTH240MSAX maintains this glitch-free bus loading even when OE pins are unconnected or floating during sequencing.

What package type is used for the 74LVTH240MSAX and what are its key mechanical features?

The 74LVTH240MSAX uses a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, 5.3mm wide with 0.65mm lead pitch. Its gull-wing leads and compact footprint (typical body size 7.6mm × 5.3mm) support high-density PCB layouts and automated SMT assembly. The package is lead-free per JEDEC J-STD-020B and rated for reflow soldering profiles up to 260°C peak temperature-ensuring compatibility with modern RoHS-compliant manufacturing processes.