The **M95640-RMB3TG** is a high-performance, electrically erasable programmable memory (EEPROM) manufactured by STMicroelectronics. It is commonly used for parameter storage in automotive, industrial, and consumer electronics. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical and physical characteristics: | Parameter | Specification | | :--- | :--- | | **Memory Size** | 64 Kbit (8,192 x 8 bits) | | **Interface** | SPI (Serial Peripheral Interface) | | **Max Clock Frequency** | 20 MHz | | **Operating Voltage ($V_{CC}$)** | 1.8V to 5.5V | | **Operating Temperature** | -40°C to +125°C | | **Package Type** | UFDFPN8 (MLP8) | | **Endurance** | 4 million write cycles | | **Data Retention** | 200 years | --- ### 2. Functional Description The device operates using the SPI protocol, which requires four signals: * **Chip Select ($\bar{S}$):** Activates the device. * **Serial Data Input (D):** Receives instructions, addresses, and data. * **Serial Data Output (Q):** Sends data out during read operations. * **Serial Clock (C):** Synchronizes data movement. It also features hardware protection pins: * **Write Protect ($\bar{W}$):** Prevents unauthorized write operations to the status register. * **Hold ($\bar{HOLD}$):** Pauses communication without resetting the chip select. --- ### 3. Part Number Breakdown Understanding the suffix "RMB3TG" helps identify the specific variant: | Code | Meaning | | :--- | :--- | | **M95** | SPI Family EEPROM | | **640** | Density (64 Kbit) | | **-R** | Low Voltage (1.8V to 5.5V) | | **MB** | UFDFPN8 Package (2x3 mm) | | **3** | Range 3 (-40 to +125°C / Automotive Grade) | | **TG** | Tape & Reel Packing / Green (Lead-free) | --- ### 4. Implementation Example (SPI Logic) Below is a conceptual example of how to interact with the M95640 using a standard SPI command structure in C: ```c // Define standard M95640 Opcodes #define WREN 0x06 // Write Enable #define WRITE 0x02 // Write to Memory Array #define READ 0x03 // Read from Memory Array void write_byte(uint16_t address, uint8_t data) { select_chip(); spi_transfer(WREN); // Must enable write latch first deselect_chip(); select_chip(); spi_transfer(WRITE); // Send Write instruction spi_transfer((address >> 8) & 0xFF); // Address MSB spi_transfer(address & 0xFF); // Address LSB spi_transfer(data); // Send data byte deselect_chip(); } ```