The **M95320-RMB3/B** is a high-performance, industrial-grade Serial Peripheral Interface (SPI) EEPROM (Electrically Erasable Programmable Memory) manufactured by STMicroelectronics. It is commonly used for parameter storage in automotive and industrial applications. --- ### 1. Key Technical Specifications The following table outlines the core electronic parameters for this specific part number: | Parameter | Specification | | :--- | :--- | | **Memory Size** | 32 Kbit (4,096 bytes x 8 bits) | | **Interface** | SPI (Mode 0 and Mode 3) | | **Operating Voltage ($V_{CC}$)** | 1.8V to 5.5V | | **Clock Frequency ($f_C$)** | Up to 20 MHz (at 4.5V - 5.5V) | | **Page Size** | 32 Bytes | | **Endurance** | 4 Million Write Cycles | | **Data Retention** | 200 Years | | **Operating Temperature** | -40°C to +125°C (Grade 3) | --- ### 2. Part Number Breakdown The suffix `RMB3/B` provides critical information regarding the physical and electrical characteristics: * **M95320**: Base series (32 Kbit SPI EEPROM). * **-R**: Indicates a wide supply voltage range (1.8V to 5.5V). * **MB**: Represents the package type, specifically **UFDFPN8** (Ultra-thin Fine pitch Dual Flat No-lead, 2x3 mm). * **3**: Indicates Device Grade 3 (Operating temperature from **-40 to +125°C**). * **B**: Reflects the specific process technology or manufacturing generation. --- ### 3. Functional Features #### SPI Protocol Support The device operates using four signals: 1. **Chip Select ($S$)**: Activates the device. 2. **Serial Data Input ($D$)**: Used to transfer data into the device. 3. **Serial Data Output ($Q$)**: Used to read data out of the device. 4. **Serial Clock ($C$)**: Synchronizes the data transfer. #### Hardware Protection * **Write Protect ($\overline{W}$)**: A hardware pin used to freeze the status register, preventing accidental writes to the memory. * **Hold ($\overline{HOLD}$)**: Allows the communication to be paused without deselecting the device, which is useful when sharing the SPI bus with other peripherals. #### Memory Organization The 32 Kbits are organized as 4,096 bytes. Instructions like `READ`, `WRITE`, `WREN` (Write Enable), and `RDSR` (Read Status Register) are used to manage the data. --- ### 4. Typical Application Circuit In a standard electronic design, the M95320-RMB3/B is connected to a Microcontroller (MCU) as follows: ```c // Connection Diagram MCU (Master) M95320 (Slave) ----------- -------------- SPI_MOSI ------> D (Pin 5) SPI_MISO <------ Q (Pin 2) SPI_SCK ------> C (Pin 6) GPIO_CS ------> S (Pin 1) VCC (3.3V) ------> VCC (Pin 8) GND ------> VSS (Pin 4) ```