The **71421LA55JGI** is a high-performance, high-speed **Dual-Port Static RAM (SRAM)** manufactured by Renesas Electronics (formerly IDT). This specific part is designed to allow two independent systems (or processors) to access a common memory space simultaneously. --- ### 1. Key Technical Specifications Below are the primary electrical and physical characteristics of the component: | Feature | Specification | | :--- | :--- | | **Memory Capacity** | 16K bits (2K x 8-bit) | | **Access Time** | 55 ns (Nanoseconds) | | **I/O Voltage** | 5.0V (Typical) | | **Package Type** | PLCC-52 (Plastic Leaded Chip Carrier) | | **Temperature Grade** | Industrial (-40°C to +85°C) | | **Process Technology** | CMOS | | **Mounting Type** | Surface Mount (SMD) | --- ### 2. Functional Description The core architecture of the 71421LA55JGI allows for asynchronous reading and writing from two separate ports (Left and Right). #### Main Components & Pins: * **Dual-Port Memory Array:** 2,048 words of 8 bits each. * **Control Logic:** Each port has its own independent Control, Address, and I/O pins. * **Arbitration / Semaphores:** It includes hardware support for "Busy" logic and "Interrupt" signals to prevent data contention when both ports try to write to the same address simultaneously. * **Low Power Mode:** The "LA" in the part number indicates a low-power version, which utilizes a "Full Standby" mode to reduce power consumption when the chip-enable pins are inactive. --- ### 3. Pinout & Connectivity The 52-pin PLCC package includes the following functional groups: | Group | Pins | Description | | :--- | :--- | :--- | | **Address Lines** | $A_0 - A_{10}$ | Identifies the 2K memory locations. | | **Data I/O** | $I/O_0 - I/O_7$ | Bi-directional data path for each port. | | **Control Signals** | $\overline{CE}, \overline{OE}, R/\overline{W}$ | Chip Enable, Output Enable, and Read/Write control. | | **Master/Slave** | $M/\overline{S}$ | Used for expanding data bus width (cascading). | | **Interrupts** | $\overline{INT}_L, \overline{INT}_R$ | Communications between the two processors. | --- ### 4. Typical Applications * **Multi-Processor Systems:** Acting as a mailbox or buffer between two different CPUs. * **Digital Signal Processing (DSP):** Passing data between a DSP chip and a General Purpose Processor. * **Networking Equipment:** Used in switches and routers for packet buffering. * **Industrial Automation:** Handling data flow between a real-time controller and a monitoring interface. --- ### 5. Part Number Decoding Understanding the nomenclature: * **71421:** Base part number (2K x 8 Dual-Port RAM). * **LA:** Low Power. * **55:** 55ns Speed Grade. * **J:** PLCC Package. * **G:** Green (RoHS compliant/Lead-free). * **I:** Industrial Temperature range.