Texas Instruments 74AC11244PW

Overview

74AC11244PW from Texas Instruments is an octal 3-state noninverting buffer/driver in a 24-pin TSSOP package, designed for memory address bus driving and clock distribution. It features dual 4-bit sections with independent active-low output-enable (OE) controls, ±24 mA output drive at 5 V, 7.3 ns max propagation delay (VCC = 5 V), and operation across –40°C to 85°C.

For engineers reviewing the 74AC11244PW datasheet, 74AC11244PW pinout, 74AC11244PW application, or 74AC11244PW equivalent, key selection considerations include 3-state bus-driving capability, flow-through pinout for PCB layout optimization, latch-up immunity (500 mA typical), and compatibility with 3-V to 5.5-V supply rails.

Technical Context

The 74AC11244PW implements two independent 4-bit noninverting buffer sections, each controlled by its own active-low OE input (1OE and 2OE). Outputs enter high-impedance state when respective OE is high, enabling bidirectional bus sharing without external logic.

Its EPIC™ 1-µm CMOS process delivers rail-to-rail output swing, low input capacitance (4 pF), and low power dissipation capacitance (27 pF enabled / 9 pF disabled). The center-pin VCC/GND configuration minimizes switching noise during high-speed transitions.

Key Specifications

Pinout & Package

TSSOP-24 (PW) package: 7.8 mm × 4.4 mm × 1.2 mm body, 0.65 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC244PWR and 74LVC244APW, the 74AC11244PW uniquely provides dual independent 4-bit sections with separate OE controls in a 24-pin TSSOP, making it optimal for applications requiring selective bus partitioning and 5-V compatibility without sacrificing layout efficiency.

Availability

74AC11244PW is available at Aetrix Electronics and suitable for memory address buffering, clock distribution, and industrial I/O expansion requiring stable component supply and long-term industrial temperature support.

Supply support for 74AC11244PW 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The 74AC11244PW belongs to TI's legacy AC logic family, engineered for high-speed, low-noise bus interfacing in industrial and computing systems where 5-V tolerance and latch-up robustness are critical.

FAQ

What is the recommended power-up sequence for the 74AC11244PW to avoid bus contention?

TI recommends tying both 1OE and 2OE to VCC through a pull-up resistor (minimum value determined by driver sink capability) to ensure outputs remain in high-impedance state during power-up. This prevents unintended driving of the bus before system initialization completes. The 74AC11244PW's internal design does not require strict VCC ramp sequencing, but OE biasing is mandatory for safe startup behavior in shared-bus systems.

Does the 74AC11244PW support mixed-voltage interfacing between 3.3-V and 5-V logic domains?

Yes - the 74AC11244PW accepts input voltages from 0 V to VCC, and its VIH/VIL thresholds scale with VCC (e.g., VIH = 3.85 V at VCC = 5.5 V). When operated at VCC = 3.3 V, it correctly interprets 3.3-V logic levels; at VCC = 5 V, it interfaces cleanly with 5-V TTL/CMOS. However, direct connection of 5-V signals to a 3.3-V-powered 74AC11244PW violates absolute maximum ratings and is not permitted.

What is the thermal performance of the 74AC11244PW in its TSSOP-24 (PW) package?

The 74AC11244PW in PW package has a specified thermal impedance θJA of 120°C/W under JEDEC JESD51 conditions. At full 8-output switching with 24 mA per output and 5 V supply, worst-case power dissipation is ~120 mW, resulting in ~14.4°C junction-to-ambient rise above board temperature - well within the –40°C to 85°C operating range. No heatsink is required for typical industrial use.

Can unused inputs on the 74AC11244PW be left floating?

No - all unused inputs must be tied to either VCC or GND to prevent oscillation, excessive current draw, and potential damage. TI's application report SCBA004 explicitly warns that floating CMOS inputs cause increased dynamic power, noise susceptibility, and possible latch-up. For the 74AC11244PW, this applies to any unconnected 1A1–1A4, 2A1–2A4, 1OE, or 2OE pins.

Is the 74AC11244PW pin-compatible with other members of the 74AC244 family?

No - the 74AC11244PW is functionally and physically distinct from standard 74AC244 variants. While both are octal buffers, the 74AC11244PW has 24 pins, dual OE inputs, and separate 4-bit sections, whereas the 74AC244 uses 20 pins and a single OE. Pinouts, package dimensions, and logic partitioning differ; substitution requires PCB redesign. Always verify against the specific 74AC11244PW pin diagram before integration.