onsemi 74LVTH244SJ

Overview

74LVTH244SJ from Fairchild Semiconductor is a low-voltage octal buffer/line driver with 3-STATE outputs, designed for memory address and clock distribution in 3.3V systems interfacing to 5V TTL buses. It features bushold inputs (eliminating external pull-ups), ±32mA/64mA drive capability, and operates from 2.7V to 3.6V supply. Used in bus-oriented transmitters/receivers where PC board density and glitch-free power-up/down behavior are critical.

For engineers reviewing the 74LVTH244SJ datasheet, pinout, applications, or equivalent options, key selection criteria include bushold input support, 20-pin SOP (EIAJ TYPE II) package compatibility, 3.3V/5V mixed-voltage interface capability, and high-current 3-STATE output drive for driving terminated transmission lines or multiple loads.

Technical Context

The 74LVTH244SJ implements dual 4-bit non-inverting buffers with independent 3-STATE enable controls (OE1/OE2). Its bushold circuitry actively maintains input logic state without external biasing-critical for floating data bus lines during hot-swap or partial system power-down. Each output supports TTL-level signaling at 5V while powered from 3.3V VCC.

It uses advanced BiCMOS fabrication to achieve ABT-class speed (tPLH/tPHL ≤ 4.2 ns @ 3.3V, CL = 50pF) with low static current (ICCZ = 0.19 mA). Power-up/down high-impedance behavior prevents bus contention during supply ramping, and latch-up immunity exceeds 500 mA per JEDEC JESD78.

Key Specifications

Pinout & Package

74LVTH244SJ is housed in a 20-lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm wide (package code M20D), with standard 1.27mm lead pitch and gull-wing terminations compatible with reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and 74ALVC244MTCX, the 74LVTH244SJ uniquely combines bushold inputs, 5V-tolerant I/O, and ±32mA/64mA drive-making it the only choice for robust 3.3V-to-5V bus bridging with zero external bias components.

Availability

74LVTH244SJ is available at Aetrix Electronics and suitable for memory address buffering, clock distribution, hot-swappable I/O expansion, and legacy bus interface bridge applications requiring stable component supply across industrial temperature ranges and long-term production cycles.

Supply support for 74LVTH244SJ 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 leading analog and power IC manufacturer, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and communications infrastructure.

The 74LVTH244SJ belongs to Fairchild's LVT/H series-designed specifically for mixed-voltage system interfacing, combining 3.3V core efficiency with 5V signal compatibility and robust bus-driving capability.

FAQ

What is the bushold function in the 74LVTH244SJ and how does it affect circuit design?

The bushold function in the 74LVTH244SJ actively maintains the last-valid logic state on each input pin without external pull-up or pull-down resistors. This eliminates the need for 10kΩ biasing components on unused data lines, reducing BOM cost and PCB area. In practice, it ensures deterministic HIGH or LOW states during power-up, standby, or partial system resets-critical for preventing metastability in bus arbitration logic. The 74LVTH244SJ requires no configuration to enable bushold; it is intrinsic to the device's input structure.

Can the 74LVTH244SJ safely interface a 3.3V microcontroller with 5V TTL peripherals?

Yes, the 74LVTH244SJ supports 5V-tolerant inputs (VI up to 5.5V) while operating from a 3.3V supply, making it ideal for interfacing 3.3V microcontrollers with legacy 5V TTL peripherals. Its outputs swing rail-to-rail within the 3.3V domain but provide sufficient noise margin (VIH ≥ 2.0V, VIL ≤ 0.8V) to reliably drive 5V TTL inputs. The 74LVTH244SJ also delivers ±32mA/64mA drive strength-exceeding standard TTL fanout requirements-ensuring signal integrity across loaded buses.

What is the significance of the "SJ" suffix in 74LVTH244SJ?

"SJ" denotes the 20-lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm wide (package code M20D), with gull-wing leads and 1.27mm pitch. This package is distinct from SOIC (WM), SSOP (MSA), and TSSOP (MTC) variants. The 74LVTH244SJ's SJ package offers mechanical compatibility with standard SOP footprints and reflow profiles, and is optimized for mid-density PCB layouts where thermal performance and hand-solderability are balanced against miniaturization.

Does the 74LVTH244SJ support hot insertion, and what design features enable this?

Yes, the 74LVTH244SJ supports live insertion/extraction per its datasheet. Key enablers include power-up/down high-impedance outputs-ensuring all O0–O7 pins enter 3-STATE before VCC stabilizes-and robust ESD protection (HBM > 2000V). These features prevent bus contention, backfeeding, or latch-up during card mating. The 74LVTH244SJ also exhibits no DC current path between powered and unpowered sections, allowing safe connection to an active backplane without disrupting system operation.

How does the 74LVTH244SJ compare to the non-bushold 74LVT244 variant?

The 74LVTH244SJ includes bushold inputs; the 74LVT244 does not. This means the 74LVTH244SJ eliminates external pull-up resistors on unused inputs, while the 74LVT244 requires them to avoid floating states. Both share identical pinout, 3-STATE control (OE1/OE2), drive strength (–32mA/+64mA), and 5V-tolerant I/O. Functionally, they are drop-in replacements except where bushold is required-so the 74LVTH244SJ is preferred in systems with variable or undefined input states during initialization or partial power-down.