Texas Instruments SN74AC244DWR

Overview

SN74AC244DWR from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented signal routing in digital systems. It operates across 2V–6V V_CC, supports 5V and 3.3V logic domains, delivers ≤7.5ns propagation delay at 5V, and features dual independent output-enable controls. It is used in server backplanes to isolate memory address buses during hot-swap events.

For engineers reviewing the SN74AC244DWR datasheet, SN74AC244DWR pinout, SN74AC244DWR application, or SN74AC244DWR equivalent, key selection criteria include its 20-pin SOIC (DW) package, rail-to-rail input voltage tolerance (up to 6V), ±24mA drive strength at 5V, 3-state output architecture, and industrial temperature range (–40°C to +85°C).

Technical Context

The SN74AC244DWR implements two independent 4-bit non-inverting buffer groups, each with dedicated output-enable (OE) inputs controlling high-impedance state entry/exit. Its AC logic family ensures compatibility with TTL and CMOS interfaces while maintaining low power consumption and fast switching.

It uses standard positive-logic control: OE low enables data pass-through (A→Y); OE high forces outputs into high-Z. Input clamping diodes allow safe interfacing with voltages up to 6V regardless of V_CC, and its 20-pin SOIC package provides mechanical stability for high-density PCB layouts.

Key Specifications

Pinout & Package

SN74AC244DWR is housed in a 20-pin SOIC (DW) package measuring 12.8mm × 10.3mm (body: 12.8mm × 7.5mm), RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and 74ACT244SC, SN74AC244DWR uniquely balances 5V bus compatibility, industrial temperature range, and low static current - making it optimal for mixed-voltage industrial and telecom equipment where long-term component availability and datasheet clarity are critical.

Availability

SN74AC244DWR is available at Aetrix Electronics and suitable for server backplane design, LED display manufacturing, and telecom infrastructure projects requiring stable component supply across multi-year production cycles.

Supply support for SN74AC244DWR 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 SN74AC244DWR belongs to TI's AC logic family - engineered for high-speed, low-power, mixed-voltage digital interfacing in mission-critical industrial and infrastructure systems.

FAQ

What is the maximum clock frequency supported by SN74AC244DWR in a bus application?

The SN74AC244DWR does not operate on a clock signal - it is a combinatorial buffer with propagation delay (t_pd) of ≤7.5ns at 5V. In practice, this supports reliable data/address transfer in synchronous systems up to approximately 100 MHz, assuming adequate setup/hold margins and proper PCB layout. For precise timing analysis, engineers must reference the SN74AC244DWR switching characteristics tables under actual V_CC and load conditions.

Can SN74AC244DWR safely interface a 3.3V microcontroller with a 5V peripheral bus?

Yes. The SN74AC244DWR accepts input voltages up to 6V regardless of V_CC, so with V_CC = 3.3V, it correctly interprets 5V logic-high signals from peripherals. Its outputs swing rail-to-rail (0V to 3.3V), making it ideal for unidirectional 5V→3.3V level translation. For bidirectional use, additional circuitry is required - the SN74AC244DWR itself is not bidirectional.

Does SN74AC244DWR require external pull-up resistors on its OE pins?

Yes - during power-up or power-down, OE pins should be held high via pull-up resistors to ensure outputs remain in high-impedance state and prevent bus contention. TI recommends connecting 10kΩ pull-ups from 1OE and 2OE to V_CC. This is explicitly required for safe operation per the SN74AC244DWR functional description and power sequencing guidelines.

What is the thermal resistance (R_θJA) of SN74AC244DWR in its SOIC (DW) package?

The junction-to-ambient thermal resistance (R_θJA) for SN74AC244DWR in the SOIC (DW) package is 101.2°C/W, as specified in the Thermal Information table. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad). For sustained operation near maximum ratings, thermal design must account for this value along with ambient temperature and power dissipation (typically <10mW per buffer at 25°C).

Is SN74AC244DWR pin-compatible with other members of the '244 family like SN74LS244 or SN74HC244?

No - while SN74AC244DWR shares the same 20-pin SOIC footprint and basic pinout (e.g., V_CC, GND, A/Y/OE locations), it is not electrically pin-compatible with SN74LS244 (TTL, 5V-only, higher ICC) or SN74HC244 (CMOS, 2–6V but lower drive: ±7.8mA). Direct substitution may cause timing violations, excessive loading, or logic-level misinterpretation. Always verify V_CC, drive strength, and input thresholds before replacement.