Texas Instruments SN74AHC244DWE4

Overview

SN74AHC244DWE4 from Texas Instruments is an octal noninverting 3-state buffer/driver IC designed for high-density bus interfacing in memory-address, clock, and data transmission systems. It operates from 2V to 5.5V, delivers ±8mA output drive at 5V, supports 3.3V/5V mixed-voltage translation, and features dual independent 4-bit banks with separate 3-state enables (1OE, 2OE). It is used in PC motherboard I/O expansion and industrial backplane buffering.

For engineers reviewing the SN74AHC244DWE4 datasheet, SN74AHC244DWE4 pinout, SN74AHC244DWE4 application, or SN74AHC244DWE4 equivalent, key selection criteria include VCC range compatibility (2–5.5V), 3-state timing (tPZH ≤ 8.5ns @5V), output drive strength (±8mA), thermal performance in SOIC-20 (RθJA = 81.1°C/W), and input overvoltage tolerance up to 5.5V regardless of VCC.

Technical Context

The SN74AHC244DWE4 implements two independent 4-bit noninverting buffer banks, each controlled by a dedicated output-enable input (1OE, 2OE). Each bank drives four outputs (e.g., 1Y1–1Y4) from corresponding inputs (1A1–1A4), with boolean function xYn = xAn. All outputs enter high-impedance state when their respective OE is high.

It uses balanced CMOS push-pull outputs capable of sourcing and sinking equal current (±8mA @5V), enabling clean signal integrity on PCB traces up to 12 cm. Input structure includes standard CMOS gates with overvoltage-tolerant inputs (VI max = 5.5V) and internal clamp diodes for ESD protection (HBM ±2000V).

Key Specifications

Pinout & Package

SN74AHC244DWE4 is housed in a 20-pin SOIC (DW) package measuring 12.80mm × 10.3mm with body size 12.8mm × 7.5mm. The package features gull-wing leads, surface-mount compatibility, and thermal performance characterized by RθJA = 81.1°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC244DWE4, SN74AHCT244N offers better TTL input compatibility but sacrifices 5.5V overvoltage tolerance, while 74LVC244APW provides higher drive at 3.3V but cannot accept 5V inputs - making SN74AHC244DWE4 uniquely suited for mixed-voltage bus bridging.

Availability

SN74AHC244DWE4 is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, industrial backplane buffering, and network switch control plane applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and voltage ranges.

Supply support for SN74AHC244DWE4 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 decades of experience in high-reliability industrial and computing applications.

SN74AHC244DWE4 belongs to TI's AHC (Advanced High-Speed CMOS) logic family, engineered for low-power, high-speed bus interfacing in mixed-voltage computing and industrial control systems.

FAQ

What is the maximum input voltage rating for SN74AHC244DWE4, and does it depend on VCC?

The SN74AHC244DWE4 supports input voltages up to 5.5V regardless of VCC setting - a key feature enabling direct interfacing with 5V signals even when powered from 3.3V or 2.5V supplies. This overvoltage tolerance eliminates external clamping diodes or level shifters in mixed-voltage systems, simplifying design and reducing BOM cost. The absolute maximum input rating remains ±0.5V beyond GND/VCC per datasheet Section 5.1.

Can SN74AHC244DWE4 drive a 50pF load at 5V with guaranteed timing performance?

Yes - SN74AHC244DWE4 guarantees tPLH/tPHL ≤ 8.5ns and tPZH/tPLZ ≤ 10.5ns when driving a 50pF load at VCC = 5V ± 0.5V and TA = 25°C (Section 5.7). These values represent worst-case maxima; typical performance is faster (e.g., tPLH typ = 5.4ns). For production designs, derating for temperature and voltage variation is recommended using the TPD vs VCC and TPD vs Temperature curves in Section 5.10.

How should unused inputs be handled on SN74AHC244DWE4?

All unused inputs on SN74AHC244DWE4 must be terminated to either VCC or GND - never left floating - to prevent excessive power consumption, oscillation, or latch-up. TI recommends 10kΩ pull-up or pull-down resistors for unconnected inputs. This requirement applies to all eight A-inputs and both OE pins if not actively driven; failure to comply violates Recommended Operating Conditions (Section 5.3, Note 1).

What is the thermal resistance (RθJA) of SN74AHC244DWE4 in its SOIC-20 package?

The SN74AHC244DWE4 in the DW (SOIC-20) package has a junction-to-ambient thermal resistance (RθJA) of 81.1°C/W, as specified in Section 5.4. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad). Actual thermal performance improves with added copper area, internal planes, or thermal vias - critical for sustained ±8mA output loading in enclosed industrial enclosures.

Does SN74AHC244DWE4 support hot-swap or live-insertion scenarios?

SN74AHC244DWE4 supports controlled hot-swap operation when both OE pins are tied to VCC via pull-up resistors during power-up/down (Section 7.1). This forces outputs into high-impedance before VCC stabilizes, preventing bus contention. However, the device itself is not hot-swap rated per IEC 61000-4-2; external current limiting and sequencing remain necessary for full system-level hot-swap compliance.