Texas Instruments SN74ACT72241L20RJ

Overview

SN74ACT72241L20RJ from Texas Instruments is a 4096 × 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. It operates from 0°C to 70°C and is used in high-speed asynchronous data bridging between independent clock domains.

For engineers reviewing the SN74ACT72241L20RJ datasheet, SN74ACT72241L20RJ pinout, SN74ACT72241L20RJ application, or SN74ACT72241L20RJ equivalent, key selection criteria include its 4096-word depth, 9-bit bus width with parity support, RCLK/WCLK independence, flag synchronization logic, and RJ-package thermal/mechanical constraints for PCB layout and signal integrity.

Technical Context

This device implements a first-in, first-out (FIFO) buffer using internal synchronous read and write address counters. Data input and output ports are fully synchronous: writes occur on low-to-high WCLK transitions when WEN1 and WEN2/LD are asserted and FF is high; reads occur on low-to-high RCLK transitions when REN1/REN2 are low and EF is high.

Empty (EF) and full (FF) flags are synchronized to RCLK and WCLK respectively via single flip-flops; programmable flags PAE and PAF use offset registers (default empty+7/full−7) and are similarly clock-synchronized. The dual-purpose WEN2/LD pin determines at reset whether the device operates with two write enables or supports flag offset programming.

Key Specifications

Pinout & Package

SN74ACT72241L20RJ is packaged in a 32-pin plastic J-leaded chip carrier (RJ), surface-mountable with gull-wing leads and 0.050-inch lead pitch. Thermal and mechanical design must account for JEDEC MS-013AC package dimensions and reflow profile compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72241L20JI and SN74ACT72241L25RJ, SN74ACT72241L20RJ delivers the highest clock rate (66.7 MHz) in the TI family while maintaining pin and functional compatibility with both alternatives-enabling drop-in upgrade paths where timing headroom is critical.

Availability

SN74ACT72241L20RJ is available at Aetrix Electronics and suitable for graphics system rate buffers, communication system high-speed queues, and industrial bus bridges requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74ACT72241L20RJ 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 specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74ACT72241L20RJ belongs to TI's ACT-family advanced CMOS FIFO product line, designed specifically for high-speed, low-latency data buffering between asynchronous clock domains in real-time systems.

FAQ

What is the memory organization of the SN74ACT72241L20RJ?

The SN74ACT72241L20RJ is organized as 4096 words × 9 bits, implemented using CMOS dual-port SRAM. This provides 36,864 bits of total storage, supporting byte-wide data plus parity or framing information. Its depth enables substantial buffering for burst-mode transfers without software intervention, and the 9-bit width matches common parallel bus architectures requiring error detection capability.

How does the SN74ACT72241L20RJ handle clock domain crossing between read and write interfaces?

The SN74ACT72241L20RJ uses fully synchronous, independent RCLK and WCLK inputs with status flags (EF, FF, PAE, PAF) registered to their respective clocks. This eliminates metastability risk during boundary detection. EF and PAE are synchronized to RCLK; FF and PAF to WCLK. The device does not require external handshaking logic-hardware flags directly inhibit illegal reads/writes, enabling robust inter-clock-domain data transfer.

Can the programmable almost-empty and almost-full flags of the SN74ACT72241L20RJ be customized, and how?

Yes-the SN74ACT72241L20RJ supports programmable PAE and PAF offsets via four 8-bit registers (empty LSB/MSB, full LSB/MSB). When WEN2/LD is held low during reset, it becomes the LD signal. Subsequent WCLK rising edges write data to these registers in sequence. Default values are empty+7 and full−7, but users can set arbitrary thresholds (e.g., trigger PAE at 32 words remaining) to optimize DMA or interrupt timing in their system.

What is the function of the WEN2/LD pin on the SN74ACT72241L20RJ, and how is its mode selected?

The WEN2/LD pin on the SN74ACT72241L20RJ is dual-function: it acts as either a second write-enable input (WEN2) or a load-enable (LD) for flag offset registers. Mode selection occurs at reset: if WEN2/LD is high when RS returns high, it functions as WEN2; if low, it becomes LD. This configuration is latched and remains fixed until next power-on or reset, allowing flexible system-level control over flag programmability versus additional write gating.

Does the SN74ACT72241L20RJ support width expansion, and what design considerations apply?

Yes-the SN74ACT72241L20RJ supports bit-width expansion by connecting multiple units in parallel. Control signals (WCLK, RCLK, REN1/REN2, WEN1, RS, OE) are shared; D0–D8 and Q0–Q8 are concatenated. Composite EF/FF must be OR'd across all devices; PAE/PAF may be monitored from any one unit. Critical considerations include matched trace lengths for clocks/controls, simultaneous reset assertion, and managing increased capacitive loading on shared buses to maintain timing margins.