Texas Instruments SN74ACT244DBR

Overview

SN74ACT244DBR from Texas Instruments is an octal 3-state non-inverting buffer/driver IC designed for bus-oriented data transmission, clock distribution, and memory address driving in 5-V TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers ±24 mA output drive per channel, achieves 9.5 ns maximum propagation delay at 5 V, and supports input voltages up to 5.5 V - enabling robust interfacing with mixed-voltage logic domains in industrial control backplanes.

For engineers reviewing the SN74ACT244DBR datasheet, SN74ACT244DBR pinout, SN74ACT244DBR application, or SN74ACT244DBR equivalent, key selection criteria include its dual 4-bit 3-state architecture with independent active-low OE controls, guaranteed 24-mA sink/source capability, TTL-compatible input thresholds, and SSOP-20 packaging optimized for high-density PCB layouts in telecom switching and LED display driver subsystems.

Technical Context

The SN74ACT244DBR implements two independent 4-bit buffer sections (1A→1Y and 2A→2Y), each controlled by a dedicated active-low output-enable (OE) input. Its TTL-compatible inputs accept VIH ≥ 2.0 V at 5 V VCC and tolerate up to 5.5 V, eliminating level-shifting requirements when interfacing with legacy 5-V logic families.

Each output exhibits rail-to-rail swing with VOH ≥ 3.76 V and VOL ≤ 0.44 V at IO = ±24 mA and VCC = 5.5 V, while maintaining low quiescent ICC ≤ 40 µA and fast switching: tPLH/tPHL ≤ 10 ns, tPZH/tPHZ ≤ 10.5 ns at 25°C. The device enters high-impedance state when OE is high, supporting bidirectional bus contention management.

Key Specifications

Pinout & Package

SN74ACT244DBR is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.2 mm × 5.3 mm body size, and exposed thermal pad (non-electrical). This RoHS-compliant, tape-and-reel packaged variant supports automated SMT assembly and provides enhanced thermal performance over standard SOIC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and SN74ALS244N, SN74ACT244DBR uniquely balances 5-V TTL compatibility, 24-mA drive, sub-10-ns timing, and modern SSOP packaging - making it the optimal choice for new industrial and telecom designs requiring backward compatibility and layout efficiency.

Availability

SN74ACT244DBR is available at Aetrix Electronics and suitable for industrial control backplanes, telecom switching networks, and LED display driver subsystems requiring stable component supply, long-term lifecycle support, and RoHS-compliant SMT packaging.

Supply support for SN74ACT244DBR 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 for industrial, automotive, and communications markets.

The SN74ACT244DBR belongs to TI's 74ACT advanced CMOS logic family, engineered for high-speed, low-noise 5-V digital interfacing in mission-critical infrastructure where reliability, timing precision, and mixed-voltage interoperability are essential.

FAQ

What is the recommended operating voltage range for SN74ACT244DBR?

The SN74ACT244DBR is specified for 4.5 V to 5.5 V VCC operation. Operation outside this range may cause functional failure or accelerated wear. At 4.5 V, VOH remains ≥3.76 V and VOL ≤0.44 V under ±24 mA load, ensuring robust noise margins in noisy industrial environments. Always decouple VCC with a 0.1-µF ceramic capacitor placed within 2 mm of pin 20.

How does SN74ACT244DBR handle input voltages exceeding VCC?

SN74ACT244DBR inputs are explicitly rated to accept voltages up to 5.5 V regardless of actual VCC value - a key feature enabling safe interfacing with 5-V peripherals during brownout conditions. This overvoltage tolerance is implemented via internal clamping diodes and does not require external protection circuitry, provided input current remains within ±20 mA absolute maximum rating.

Can SN74ACT244DBR drive LEDs directly?

Yes, SN74ACT244DBR can drive LEDs directly in sink or source configuration. Each output delivers ±24 mA, so a 1-kΩ current-limiting resistor at 5 V yields ~5 mA per segment - well within safe operating limits. For higher brightness, reduce resistance while verifying IOL ≤ 24 mA and VOL ≤ 0.44 V per the datasheet's electrical characteristics table.

What is the thermal resistance (RθJA) of SN74ACT244DBR in its SSOP package?

The SN74ACT244DBR in DB (SSOP-20) package has a junction-to-ambient thermal resistance (RθJA) of 117.2 °C/W under JEDEC JESD51-2 conditions. This value assumes a standard 2-layer PCB with 1 in² copper pour. For sustained 24-mA per-output operation, derate power dissipation above 70°C ambient or add local copper thermal vias beneath the package body to improve heat transfer.

Are unused inputs on SN74ACT244DBR required to be terminated?

Yes, all unused inputs on SN74ACT244DBR must be tied to either VCC or GND. Floating inputs can induce oscillation, increase ICC, and cause unpredictable output states due to internal CMOS gate threshold sensitivity. TI recommends tying unused A inputs to GND and OE inputs to VCC via 10-kΩ pull-ups to ensure defined high-impedance startup behavior and ESD-safe biasing.