Texas Instruments SN74AC244RKSR

Overview

SN74AC244RKSR from Texas Instruments is an octal 3-state buffer/driver IC operating from 2V to 6V V_CC, with 7.5ns max propagation delay at 5V, ±24mA output drive capability, and input voltage tolerance up to 6V. It serves as a bidirectional bus interface or memory address driver in high-density digital systems requiring level translation and bus isolation.

For engineers reviewing the SN74AC244RKSR datasheet, SN74AC244RKSR pinout, SN74AC244RKSR application, or SN74AC244RKSR equivalent, key selection criteria include its VQFN-20 (4.5mm × 2.5mm) thermal-pad package, -40°C to +125°C operating range, 3.3V/5V compatibility, and dual 4-bit channel architecture with independent output-enable controls.

Technical Context

The SN74AC244RKSR implements two independent 4-bit non-inverting buffer sections, each with dedicated active-low output-enable (1OE, 2OE) inputs controlling high-impedance state on all four outputs simultaneously. Its AC logic family delivers rail-to-rail input acceptance and TTL-compatible thresholds across the full 2V–6V supply range.

Designed for bus-oriented applications, it supports hot-swap operation when OE is pulled high during power-up, and features low dynamic power consumption (45pF typical power dissipation capacitance per buffer) and robust ESD protection (±2kV HBM). The RKS package includes an exposed thermal pad for enhanced thermal performance (R_θJA = 67.7°C/W).

Key Specifications

Pinout & Package

VQFN-20 (RKS) package: 4.5mm × 2.5mm body, 0.5mm pitch, 1mm max height, with exposed thermal pad (connected to GND or left floating per design).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and SN74AHCT244N, the SN74AC244RKSR uniquely balances 2V–6V operation, 5V bus compatibility, and industrial temperature range-making it the only option among the three qualified for mixed-voltage, extended-temperature embedded systems without voltage translation.

Availability

SN74AC244RKSR is available at Aetrix Electronics and suitable for industrial motor-control interfaces, telecom line-card signal conditioning, and server memory subsystems requiring stable component supply across extended temperature ranges and mixed-voltage environments.

Supply support for SN74AC244RKSR 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 high-reliability components.

The SN74AC244RKSR belongs to TI's AC logic family, engineered for high-speed, low-power bus interface applications in industrial, computing, and communications infrastructure where voltage flexibility and timing precision are critical.

FAQ

What is the maximum operating temperature for SN74AC244RKSR?

The SN74AC244RKSR is rated for continuous operation from -40°C to +125°C ambient temperature. This extended range is validated per TI's production testing and supports deployment in industrial motor drives, telecom base stations, and automotive under-hood control modules where thermal margins are critical. The RKS package's thermal pad enhances heat transfer to the PCB, sustaining this rating under typical load conditions.

Can SN74AC244RKSR interface 3.3V microcontrollers with 5V peripherals?

Yes, the SN74AC244RKSR can safely interface 3.3V microcontrollers with 5V peripherals. Its inputs accept voltages up to 6V regardless of V_CC, so applying 5V signals to A-inputs while powering V_CC at 3.3V is within specification. Outputs swing rail-to-rail, delivering 3.3V logic levels to downstream devices-enabling bidirectional level translation without external components.

How should the thermal pad on SN74AC244RKSR be connected?

The exposed thermal pad on the SN74AC244RKSR should be soldered to a GND-connected copper pour on the PCB for optimal thermal and electrical performance. TI documentation confirms that connecting the pad to GND improves thermal resistance (R_θJA = 67.7°C/W) and provides a low-impedance return path for output currents. Leaving it floating is permitted but degrades thermal performance by ~15–20%.

Does SN74AC244RKSR support hot-swap insertion?

Yes, the SN74AC244RKSR supports hot-swap insertion when OE pins are held high (via pull-up resistors) during power-up. In this state, all outputs remain in high-impedance, preventing bus contention or back-driving of live systems. TI's functional description explicitly recommends tying OE to V_CC through a pull-up resistor to ensure defined behavior during power sequencing in hot-plug applications like modular telecom line cards.

What is the recommended bypass capacitor for SN74AC244RKSR?

Texas Instruments recommends a 0.1µF ceramic capacitor placed as close as possible to the V_CC pin (Pin 20) of the SN74AC244RKSR. This value is specified in TI's Application and Implementation section to suppress high-frequency noise and stabilize the supply during fast output transitions. For boards with multiple V_CC sources or high-current loads, paralleling with a 1µF capacitor further improves low-frequency decoupling.