The **71421LA55PFG** is a high-performance, high-speed **Dual-Port Static RAM (SRAM)** manufactured by Renesas Electronics (formerly Integrated Device Technology - IDT). This specific component is designed to facilitate independent access to a common memory array from two separate ports. --- ## 1. Technical Specifications The following table outlines the primary electrical and physical characteristics of the 71421LA55PFG. | Parameter | Specification | | :--- | :--- | | **Component Type** | Dual-Port Static RAM (SRAM) | | **Density** | 16 Kilobits (2K x 8 bits) | | **Access Time** | 55 nanoseconds (ns) | | **Operating Voltage** | 5.0V (± 10%) | | **Package Type** | TQFP-64 (Thin Quad Flat Pack, 64 pins) | | **Power Consumption** | Low Power ("LA" version) | | **Temperature Range** | Industrial/Commercial (Green/Pb-Free) | --- ## 2. Key Internal Features ### Dual-Port Architecture The device features two completely independent ports (Left and Right) that contain their own: * **Address Lines:** To select the memory location. * **Data Lines:** For 8-bit wide data I/O. * **Control Signals:** Including Read/Write ($R/\overline{W}$), Chip Enable ($\overline{CE}$), and Output Enable ($\overline{OE}$). ### Master/Slave Functionality The 71421 is a **Master** device. When used in 16-bit or wider systems, it provides the necessary arbitration logic (BUSY signals) to prevent data contention when both ports attempt to write to the same memory location simultaneously. ### Low Power (LA) Technology The "LA" designation indicates that the chip utilizes a low-power process, which reduces the standing (idle) current. This is critical for systems where thermal management or power efficiency is a priority. --- ## 3. Pinout and Signal Categories The 64-pin TQFP package organizes signals into the following categories: 1. **Address Inputs ($A_0 - A_{10}$):** Used to select one of the 2,048 available bytes. 2. **Data I/O ($I/O_0 - I/O_7$):** The 8-bit bidirectional data bus. 3. **Control Pins:** * $\overline{CE}$: Chip Enable (activates the port). * $R/\overline{W}$: Read or Write selection. * $\overline{OE}$: Output Enable (controls data flow to the pins). * $\overline{SEM}$: Semaphore Enable (for non-simultaneous resource sharing). * $\overline{INT}$: Interrupt flags for communication between processors. * $\overline{BUSY}$: Hardware signal indicating a port collision. --- ## 4. Part Number Decoder Understanding the suffix helps in identifying exact replacements: * **71421:** Base Part Number (2K x 8 Master Dual-Port RAM). * **LA:** Low Power. * **55:** 55ns Speed Grade. * **PFG:** 64-pin TQFP (Plastic) - Green/RoHS compliant. --- ## 5. Typical Applications * **Inter-processor Communication:** Allowing two different CPUs (e.g., a DSP and a Microcontroller) to share data. * **Buffering:** Acting as a bridge between two systems operating at different speeds. * **Network Equipment:** Handling packet data between different interface controllers.