The **7140LA55JGI8** is a high-performance CMOS Dual-Port Static RAM (SRAM) manufactured by Renesas Electronics (formerly IDT - Integrated Device Technology). It is designed to allow simultaneous access to a common memory array from two independent ports. --- ## 1. Technical Specifications The following table summarizes the key electrical and physical characteristics of the component: | Feature | Specification | | :--- | :--- | | **Memory Type** | SRAM - Dual Port, Asynchronous | | **Memory Size** | 8K bit (1K x 8 bits) | | **Access Time** | 55 ns | | **Voltage Supply** | 4.5V ~ 5.5V | | **Package / Case** | 52-LCC (J-Lead), PLCC | | **Operating Temperature** | -40°C ~ 85°C (Industrial Grade) | | **Interface** | Parallel | | **Power Consumption** | Low Power (LA Series) | --- ## 2. Core Functional Parts The internal architecture of the 7140LA55JGI8 consists of several critical blocks that manage data flow and collision prevention: ### A. Memory Array A 1024 x 8-bit static RAM core. Unlike standard SRAM, each cell is "dual-ported," meaning it has two sets of address, data, and control lines. ### B. Independent Control Logic Each port (Left and Right) has its own: * **Address Inputs (A0-A9):** To select the memory location. * **Data I/O (DQ0-DQ7):** For 8-bit data transfer. * **Control Pins:** * `CE` (Chip Enable) * `OE` (Output Enable) * `R/W` (Read/Write) ### C. Arbitration & Interrupt Logic Since two processors might try to write to the same address simultaneously, the chip includes: * **Busy Logic (`BUSY` pins):** Provides a hardware signal if both ports attempt to access the same location at the same time. * **Interrupt Logic (`INT` pins):** Used for inter-processor communication, allowing one port to "flag" the other. --- ## 3. Part Number Decoder Understanding the suffix codes helps identify the specific variant: | Code | Meaning | | :--- | :--- | | **7140** | Part Family (1K x 8 Dual-Port RAM) | | **LA** | Low Power version | | **55** | 55 nanosecond access speed | | **JG** | PLCC (Plastic Leaded Chip Carrier) Green/RoHS package | | **I** | Industrial Temperature range | | **8** | Tape and Reel packaging | --- ## 4. Typical Applications * **Inter-Processor Communication:** Sharing data between a DSP and a Microcontroller. * **Dual-Bus Systems:** Connecting a local bus to a system bus (e.g., PCI or VME). * **Buffered Data Transfer:** Acting as a high-speed buffer for network controllers or video processing units.