Texas Instruments SN74ACT2228DWR

Overview

SN74ACT2228DWR from Texas Instruments is a dual clocked FIFO memory IC with two independent 256 × 1-bit serial data buffers, supporting asynchronous read/write clocks up to 22 MHz and 20 ns access time. It features synchronized input-ready/output-ready flags, half-full, and almost-full/almost-empty status outputs - designed for elastic store applications in T2-rate telecommunication systems.

For engineers reviewing the SN74ACT2228DWR datasheet, SN74ACT2228DWR pinout, SN74ACT2228DWR application, or SN74ACT2228DWR equivalent, key selection criteria include its 256-word depth per FIFO, DW-package SOIC-24 footprint, 4.5–5.5 V supply range, –40°C to 85°C industrial temperature rating, and dual-asynchronous-clock timing architecture.

Technical Context

The SN74ACT2228DWR implements two independent synchronous FIFOs using dual-port SRAM cores (256 × 1 bit each), with separate write and read pointer logic per channel. Each FIFO employs multistage flip-flop synchronization: input-ready (IR) flags are synchronized to their respective write clocks via two stages, while output-ready (OR) flags use three stages tied to read clocks.

Status generation is deterministic: half-full (HF) asserts when ≥128 bits are stored; almost-full/almost-empty (AF/AE) asserts when ≤8 locations remain full or empty. Reset requires four low-to-high transitions on both RDCLK and WRTCLK while RESET is low, initializing HF/IR/OR low and AF/AE high.

Key Specifications

Pinout & Package

SN74ACT2228DWR is packaged in a 24-pin small-outline integrated circuit (SOIC) with DW package drawing, 3.9 mm body width, and 1.27 mm lead pitch. Pin 1 is located in quadrant Q1 of the tape-and-reel carrier.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FIFO memory applications.

Compared with SN74ACT2226DWR and 7200L15J8, SN74ACT2228DWR uniquely delivers 256-word serial buffering in a compact SOIC-24 package with fully asynchronous dual-clock operation - making it optimal for modern TDM and telecom elastic store implementations where depth, footprint, and clock flexibility are jointly critical.

Availability

SN74ACT2228DWR is available at Aetrix Electronics and suitable for telecom infrastructure, industrial serial bridges, TDM multiplexers, and legacy protocol adapters requiring stable component supply across extended product lifecycles.

Supply support for SN74ACT2228DWR 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 technologies with over 90 years of innovation in industrial, automotive, and communications markets.

The SN74ACT2228DWR belongs to TI's legacy ACT logic FIFO family, engineered specifically for high-reliability serial data buffering in telecom and industrial timing-critical systems where deterministic latency and robust clock-domain isolation are mandatory.

FAQ

What is the FIFO depth of SN74ACT2228DWR?

The SN74ACT2228DWR contains two independent FIFOs, each with a depth of 256 words × 1 bit. This is explicitly defined in the device description and functional block diagram, distinguishing it from the 64-word SN74ACT2226 variant. The 256-word depth enables longer jitter absorption in T2-rate telecommunication applications and supports larger burst-handling windows in serial bridging scenarios.

Does SN74ACT2228DWR support asynchronous read and write clocks?

Yes, SN74ACT2228DWR supports fully asynchronous read and write clocks per FIFO. The datasheet confirms that "free-running read and write clocks can be asynchronous or coincident on each FIFO," and the functional block diagrams show independent RDCLK and WRTCLK inputs with no shared timing constraints. This architecture is fundamental to its role as an elastic store.

How is the reset sequence executed on SN74ACT2228DWR?

The SN74ACT2228DWR requires a specific hardware reset sequence: four low-to-high transitions on both RDCLK and WRTCLK while the RESET pin is held low. After completion, HF and IR flags go low, OR goes low, and AF/AE goes high. This deterministic initialization ensures pointer alignment and flag consistency - critical before first-use in production systems.

What are the voltage and temperature ratings for SN74ACT2228DWR?

SN74ACT2228DWR operates from 4.5 V to 5.5 V supply voltage and is characterized for –40°C to +85°C ambient temperature. These values are specified in the "Recommended Operating Conditions" table. Absolute maximum ratings extend to –0.5 V to 7 V supply and –65°C to 150°C storage, but functional operation is guaranteed only within the recommended ranges.

Is SN74ACT2228DWR pin-compatible with SN74ACT2226DWR?

Yes, SN74ACT2228DWR is pin-compatible with SN74ACT2226DWR - both use the same DW (SOIC-24) package and share identical pin functions and assignments, as confirmed by the shared pinout diagram and terminal function table. The only functional difference is FIFO depth (256 vs. 64 words), making them drop-in replacements where depth sufficiency is verified.