Texas Instruments SN74ALVCH244NSRE4

Overview

SN74ALVCH244NSRE4 from Texas Instruments is an octal buffer/driver with 3-state outputs, designed for 1.65-V to 3.6-V operation. It features ±24-mA output drive at 3.3 V, 2.8-ns max propagation delay, bus-hold circuitry on all data inputs, and dual independent 4-bit channels with separate output-enable (OE) controls - used in bidirectional bus interfacing between low-voltage logic domains in industrial control backplanes.

For engineers reviewing the SN74ALVCH244NSRE4 datasheet, SN74ALVCH244NSRE4 pinout, SN74ALVCH244NSRE4 application, or SN74ALVCH244NSRE4 equivalent, key selection criteria include voltage compatibility across mixed-supply systems, high-speed 3-state timing margins, latch-up immunity (>250 mA), ESD robustness (2000-V HBM), and elimination of external biasing via integrated bus-hold.

Technical Context

This device implements two independent 4-bit noninverting buffers, each with dedicated OE control (1OE and 2OE). Inputs are internally terminated with bus-hold circuitry, eliminating need for external pullup/pulldown resistors while maintaining valid logic states on undriven lines.

Each output transitions to high-impedance when its respective OE is high; data passes from A-inputs to Y-outputs only when OE is low. The design supports hot-swap and partial-power-down scenarios via OE tie-high with pullup resistor to ensure defined startup state.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5-mm × 4.4-mm body, 1.2-mm max height, 0.65-mm lead pitch, exposed pad not present, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and SN74AHC244PW, SN74ALVCH244NSRE4 uniquely combines bus-hold, full 1.65–3.6-V operation, and 2.8-ns speed - making it optimal for modern low-voltage embedded systems requiring zero-bias reliability and timing-critical bus isolation.

Availability

SN74ALVCH244NSRE4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, FPGA I/O expansion, low-power sensor hubs, and legacy microcontroller bus interfacing requiring stable component supply across extended temperature ranges (-40°C to +85°C).

Supply support for SN74ALVCH244NSRE4 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 specializing in analog, embedded processing, and connectivity technologies, with decades of experience in high-reliability logic and interface solutions.

The SN74ALVCH244NSRE4 belongs to TI's ALVC/ALVCH advanced low-voltage CMOS logic family, engineered for low-noise, high-speed digital interfacing in space-constrained industrial and communications equipment.

FAQ

What is the recommended power-up sequence for SN74ALVCH244NSRE4?

TI recommends tying both 1OE and 2OE to VCC through a pullup resistor (minimum value determined by driver sink capability) before applying VCC. This ensures outputs remain in high-impedance during power ramp-up, preventing bus contention. For SN74ALVCH244NSRE4, a 10-kΩ resistor is typically sufficient given its input leakage of ±5 µA at 3.6 V. Always verify OE state before releasing reset in the host system.

Does SN74ALVCH244NSRE4 require external pullup or pulldown resistors on its A-inputs?

No - SN74ALVCH244NSRE4 integrates active bus-hold circuitry on all eight A-inputs, which maintains valid logic states (VIH/VIL) without external biasing. TI explicitly warns against using pullup/pulldown resistors with bus-hold enabled, as they may conflict with internal clamping and increase power consumption. This feature directly reduces BOM count and improves reliability in floating-input scenarios.

Can SN74ALVCH244NSRE4 operate reliably at 1.65 V supply?

Yes - SN74ALVCH244NSRE4 is fully specified down to 1.65 V, with guaranteed parameters including VIH (0.65×VCC), VIL (0.35×VCC), and tpd (max 4.5 ns). At 1.65 V, it delivers ±4 mA output drive and maintains bus-hold functionality. This makes SN74ALVCH244NSRE4 suitable for ultra-low-power battery-operated devices where supply rails dip near minimum logic thresholds.

What is the thermal resistance (θJA) of the TSSOP-20 package used in SN74ALVCH244NSRE4?

The TSSOP-20 (PW) package for SN74ALVCH244NSRE4 has a junction-to-ambient thermal resistance (θJA) of 83°C/W under standard JEDEC test conditions (1-layer board, 1-in² copper). This value assumes no internal thermal vias or enhanced heatsinking; actual θJA improves significantly with PCB copper area and thermal via placement beneath the package body.

How does the bus-hold circuitry in SN74ALVCH244NSRE4 affect input current specifications?

SN74ALVCH244NSRE4's bus-hold function draws ±45 µA (at 2.3 V) or ±75 µA (at 3 V) to actively retain input logic states - distinct from standard input leakage (±5 µA). This intentional current enables dynamic hold behavior but must be accounted for in total system current budgeting. Unlike passive resistors, bus-hold current scales with VCC and input overdrive, offering adaptive noise immunity without fixed power penalty.