Texas Instruments SN74AHCT244DW

Overview

SN74AHCT244DW from Texas Instruments is an octal 3-state buffer/driver IC designed for bus interface applications requiring TTL-compatible inputs, 5-V operation, and controlled output drive to minimize ringing. It features two independent 4-bit channels with separate output-enable (1OE, 2OE) controls, ±8 mA output drive at 5 V, and operates from –40°C to 85°C in a 20-pin SOIC package. It is used in PC motherboard I/O expansion, industrial control backplanes, and legacy 5-V data buses.

For engineers reviewing the SN74AHCT244DW datasheet, SN74AHCT244DW pinout, SN74AHCT244DW application, or SN74AHCT244DW equivalent, this page delivers verified electrical specs, functional mode behavior, thermal metrics for SOIC-DW, real-world layout guidance, and validated alternative options for 5-V bus buffering where slow edge rates and TTL-level compatibility are critical.

Technical Context

The SN74AHCT244DW implements two independent 4-bit non-inverting buffers, each with dedicated 3-state output-enable logic. Its CMOS design accepts TTL-voltage inputs (VIH = 2 V, VIL = 0.8 V), enabling reliable interfacing with 3.3-V logic while driving 5-V buses. Output enable pins (1OE, 2OE) control high-impedance states independently per group, supporting bidirectional bus arbitration without contention.

It uses standard AHCT-series silicon with balanced rise/fall times (~7–9 ns typical propagation delay at 15 pF), low power dissipation capacitance (8.2 pF), and latch-up immunity exceeding 250 mA per JESD17. The device is not designed for hot-swap or live-insertion; OE must be tied high via pullup during power-up/down to ensure defined high-Z state.

Key Specifications

Pinout & Package

SN74AHCT244DW is housed in a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.8 mm × 7.5 mm), with gull-wing leads and RoHS-compliant NiPdAu plating. It has a moisture sensitivity level (MSL) rating of Level-1 (unlimited floor life at ≤30°C/60% RH).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT244DW, SN74AHCT244DWR offers identical performance and form factor with guaranteed availability, while SN74LVC244APWR trades TTL compatibility and 5-V operation for lower voltage support and higher speed - making it unsuitable as a drop-in replacement in mixed-voltage or legacy 5-V systems.

Availability

SN74AHCT244DW is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, industrial PLC backplane interface, and test equipment digital pattern generation requiring stable component supply and proven 5-V bus interface reliability.

Supply support for SN74AHCT244DW 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 logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHCT244DW belongs to TI's legacy 74AHCT logic family, engineered for robust 5-V bus interfacing in systems demanding TTL compatibility, noise immunity, and predictable 3-state timing - particularly in industrial control and legacy computing infrastructure.

FAQ

What is the operating temperature range for SN74AHCT244DW?

The SN74AHCT244DW is specified for operation from –40°C to +85°C. This industrial-grade range supports deployment in embedded controllers, test equipment, and PC peripherals exposed to ambient thermal variations. The device's thermal resistance (RθJA = 81.1 °C/W) allows full-rated output drive within this range when mounted on standard FR-4 PCBs with adequate copper area.

Can SN74AHCT244DW interface 3.3-V microcontrollers with 5-V peripherals?

Yes, the SN74AHCT244DW accepts TTL-compatible inputs (VIH = 2.0 V min, VIL = 0.8 V max), enabling direct connection to 3.3-V GPIOs without level shifters. Its 5-V outputs drive standard 5-V logic loads with ±8 mA capability. This makes SN74AHCT244DW ideal for bridging voltage domains in mixed-signal systems like medical imaging subsystems or industrial gateways.

Is SN74AHCT244DW pin-compatible with other 74-series octal buffers?

SN74AHCT244DW shares the standard 20-pin SOIC (DW) footprint and pinout with SN74AHCT244DWR, SN74LS244N, and SN74F244N. However, logic thresholds, drive strength, and propagation delays differ significantly - LS and F variants require higher input current and lack TTL-voltage compatibility. Always verify timing and DC specs before substitution.

How should unused inputs be handled on SN74AHCT244DW?

All unused inputs on SN74AHCT244DW must be tied to VCC or GND to prevent floating states that cause excessive ICC, oscillation, or undefined outputs. TI recommends pullup resistors (≤10 kΩ) for inputs intended HIGH and pulldown resistors (≤10 kΩ) for LOW. Leaving inputs unconnected violates recommended operating conditions and may compromise SN74AHCT244DW reliability in long-term operation.

Does SN74AHCT244DW support hot-swap or live insertion?

No, SN74AHCT244DW does not support hot-swap. Its output-enable logic requires stable VCC before OE is asserted; applying signals before power-up risks latch-up or undefined outputs. For safe insertion, tie 1OE and 2OE to VCC through 10-kΩ pullup resistors, and ensure power sequencing places VCC before any input signals. This prevents bus contention and protects SN74AHCT244DW during board insertion.