Texas Instruments SN74ACT72221L50RJ

Overview

SN74ACT72221L50RJ from Texas Instruments is a 1024 × 9-bit synchronous dual-clock FIFO memory IC with CMOS dual-port SRAM architecture, 15 ns write/read cycle time, TTL-compatible inputs, and programmable almost-empty/almost-full flags (default offsets: empty+7 / full−7). It operates from 0°C to 70°C and is used in high-speed asynchronous data bridging between buses in communication systems.

For engineers reviewing the SN74ACT72221L50RJ datasheet, SN74ACT72221L50RJ pinout, SN74ACT72221L50RJ application, or SN74ACT72221L50RJ equivalent, key selection criteria include its 32-pin RJ package, independent RCLK/WCLK operation, flag synchronization logic, 9-bit data path with parity support, and compatibility with IDT72221 family devices.

Technical Context

This FIFO implements first-in-first-out buffering using internal synchronous read/write address counters and dual-port SRAM. Write operations are controlled by WCLK, WEN1, and WEN2/LD; reads by RCLK, REN1, and REN2 - all fully independent for asynchronous operation or coincident single-clock use.

Flag logic includes EF (synchronized to RCLK) and FF (synchronized to WCLK) for absolute boundary detection, plus PAE and PAF (each synchronized to their respective clock domains) with offset registers programmable via WEN2/LD during reset configuration. Reset initializes pointers, sets default flag states, and loads offset registers.

Key Specifications

Pinout & Package

Package: 32-pin plastic J-leaded chip carrier (RJ), surface-mount, leaded ceramic-style footprint with gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72221L15JI and SN74ACT72221L20RJ, the SN74ACT72221L50RJ delivers highest clock frequency (66.7 MHz) in the family while retaining full functional and pin compatibility - making it optimal for bandwidth-constrained, commercial-temperature applications where speed is decisive.

Availability

SN74ACT72221L50RJ is available at Aetrix Electronics and suitable for graphics rate buffering, high-speed communication queuing, and industrial bus protocol translation requiring stable component supply and long-term production continuity.

Supply support for SN74ACT72221L50RJ 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 deep heritage in high-reliability interface and memory products.

The SN74ACT72221L50RJ belongs to TI's ACT-family advanced CMOS FIFO portfolio, designed specifically for robust, low-latency data buffering across asynchronous clock domains in communications, graphics, and industrial control systems.

FAQ

What is the memory capacity and data width of the SN74ACT72221L50RJ?

The SN74ACT72221L50RJ provides 1024 words of storage, each 9 bits wide - totaling 9216 bits. This 9-bit width supports 8-bit data plus parity or protocol framing bits. The device uses dual-port CMOS SRAM with synchronous read/write address counters to implement true FIFO behavior with first-in-first-out data ordering.

How does the SN74ACT72221L50RJ handle clock domain crossing between write and read interfaces?

The SN74ACT72221L50RJ natively supports asynchronous clock domains: WCLK controls writes and RCLK controls reads, and they may run independently at different frequencies or phases. EF and FF flags are synchronized to their respective clocks (RCLK and WCLK), eliminating metastability without external synchronizers - a core design feature confirmed in the functional block diagram and timing specifications.

Can the programmable almost-empty and almost-full flags of the SN74ACT72221L50RJ be customized, and how?

Yes - the SN74ACT72221L50RJ includes four 8-bit offset registers (empty LSB/MSB, full LSB/MSB) accessible via WEN2/LD configured as LD during reset. Writing to these registers changes PAE and PAF trigger points from defaults (empty+7 / full−7) to user-defined thresholds, enabling precise flow control integration with host processor interrupt or DMA logic.

What is the package type and pin count of the SN74ACT72221L50RJ, and is it RoHS-compliant?

The SN74ACT72221L50RJ uses a 32-pin plastic J-leaded chip carrier (RJ package), a surface-mount gull-wing leaded package. While the original 1993 datasheet predates RoHS, current production batches from Texas Instruments are RoHS-compliant and halogen-free; confirm compliance via TI's official product change notices or packaging specification documents.

Is the SN74ACT72221L50RJ pin-compatible with other members of the SN74ACT722xxL family?

No - the SN74ACT72221L50RJ is not pin-compatible with SN74ACT72211L, SN74ACT72231L, or SN74ACT72241L. Although all share the same RJ package and pinout, differences in internal memory depth (512/1024/2048/4096 words) affect flag timing behavior and offset register bit widths (e.g., full-offset MSB size scales with depth), requiring validation per device variant.