Texas Instruments SN74AHC244DBRE4

Overview

SN74AHC244DBRE4 from Texas Instruments is an octal 3-state noninverting buffer/driver IC designed for bus interface and memory-address driver applications. It operates across 2V–5.5V V_CC, delivers ±8mA output drive at 5V, supports 10ns typical propagation delay (t_PLH/t_PHL) under 50pF load, and features dual independent 4-bit banks each controlled by a dedicated output enable pin. It is used in PC motherboard I/O expansion, industrial PLC backplane buffering, and test equipment signal routing.

For engineers reviewing the SN74AHC244DBRE4 datasheet, SN74AHC244DBRE4 pinout, SN74AHC244DBRE4 application, or SN74AHC244DBRE4 equivalent, key selection criteria include its 20-pin SSOP package, 3.3V/5V logic compatibility, high-impedance output control per bank, low input leakage (<±1µA), and balanced CMOS push-pull outputs with ±25mA absolute max sink/source capability.

Technical Context

The SN74AHC244DBRE4 implements two independent 4-bit noninverting buffer banks (Bank 1: pins 1A1–1A4 → 1Y1–1Y4; Bank 2: 2A1–2A4 → 2Y1–2Y4), each enabled by separate active-low OE inputs (1OE on pin 1, 2OE on pin 19). Its CMOS architecture ensures rail-to-rail output swing, input overvoltage tolerance up to 5.5V regardless of V_CC, and fast edge rates requiring careful PCB layout to suppress ringing.

Functional mode is strictly defined by OE state: when OE = L, outputs follow inputs with t_PLH/t_PHL ≤ 8.5ns (V_CC = 5V, C_L = 50pF); when OE = H, outputs enter high-impedance state with leakage ≤ ±2.5µA. Unused inputs must be tied to V_CC or GND; outputs may float in 3-state but require external pull-up/down if node voltage must be defined.

Key Specifications

Pinout & Package

SN74AHC244DBRE4 uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65mm lead pitch, 7.2mm × 7.8mm body size, and 7.50mm × 5.30mm footprint. The package is RoHS-compliant and optimized for automated surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC244APWR and 74AHC244PW,118, the SN74AHC244DBRE4 uniquely combines 5V-tolerant inputs, 2V–5.5V operation, and SSOP packaging - making it the only option supporting legacy 5V bus integration without level shifters while fitting space-constrained industrial layouts.

Availability

SN74AHC244DBRE4 is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, industrial PLC backplane buffering, and wearable health device sensor interface requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for SN74AHC244DBRE4 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 50 years of innovation in high-reliability interface and signal conditioning ICs.

The SN74AHC244DBRE4 belongs to TI's AHC logic family, engineered for high-speed, low-power, 3-state bus interface applications in computing, industrial automation, and test equipment where voltage flexibility and noise immunity are critical.

FAQ

What is the maximum output current rating for SN74AHC244DBRE4?

The SN74AHC244DBRE4 has a continuous output current rating of ±25mA per pin, with absolute maximum limits specified in the Absolute Maximum Ratings table. Under recommended operating conditions (V_CC = 5V), it delivers ±8mA high- and low-level output current while maintaining VOH ≥ 3.8V and VOL ≤ 0.44V - sufficient for driving standard TTL/CMOS loads and moderate PCB trace capacitance without external buffering.

Does SN74AHC244DBRE4 support 5V logic levels when powered from 3.3V?

Yes, the SN74AHC244DBRE4 supports 5V-tolerant inputs: its VI rating extends to 5.5V regardless of V_CC level, allowing direct connection of 5V signals to input pins even when V_CC = 3.3V. However, output swing remains rail-to-rail relative to V_CC, so outputs will swing 0–3.3V - not 0–5V - unless V_CC is set to 5V.

How should unused inputs be handled on SN74AHC244DBRE4?

All unused inputs on the SN74AHC244DBRE4 must be terminated to a valid logic level - either V_CC or GND - to prevent floating states that cause excessive power consumption or oscillation. TI recommends 10kΩ pull-up or pull-down resistors for unconnected inputs. Leaving inputs floating violates the Recommended Operating Conditions and risks device malfunction.

What is the thermal resistance (R_θJA) of the SN74AHC244DBRE4 SSOP package?

The SN74AHC244DBRE4 in DB (SSOP-20) package has a junction-to-ambient thermal resistance (R_θJA) of 99.9°C/W under standard JEDEC test conditions. This value assumes a two-layer board with minimal copper; actual thermal performance improves significantly with internal ground/power planes and thermal vias beneath the package body.

Can SN74AHC244DBRE4 outputs be safely tied together in wired-OR configuration?

No - SN74AHC244DBRE4 outputs must never be directly paralleled in wired-OR fashion. Its CMOS push-pull outputs actively drive both high and low states; connecting outputs together creates bus contention and can exceed the ±25mA absolute maximum current rating, risking permanent damage. Use open-drain alternatives or external OR-gating logic for wired-OR functionality.