The **M95128-RBN3** is a specific variant of the 128-Kbit serial SPI (Serial Peripheral Interface) EEPROM manufactured by STMicroelectronics. It is widely used in applications requiring non-volatile storage for parameters, configuration data, and small lookup tables. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 128 Kbit (16,384 bytes) | | **Interface** | SPI (Serial Peripheral Interface) | | **Clock Frequency** | Up to 20 MHz (depending on VCC) | | **Supply Voltage (VCC)** | 1.8V to 5.5V | | **Operating Temperature** | -40°C to +125°C | | **Endurance** | 4 million write cycles | | **Data Retention** | 200 years | | **Package Type** | MLP / DFN (usually 2x3 mm) | --- ### 2. PIN Configuration The device typically uses an 8-pin layout. Understanding the pin functions is critical for circuit design: * **S (Chip Select):** Activates the device when pulled low. * **D (Serial Data Input):** Receives instructions, addresses, and data. * **Q (Serial Data Output):** Sends data back to the host microcontroller. * **C (Serial Clock):** Provides the timing for data synchronization. * **W (Write Protect):** Hardware protection to prevent accidental writes to the status register. * **HOLD:** Pauses serial communication without resetting the chip select. * **VCC/VSS:** Power supply and Ground. --- ### 3. Part Number Breakdown: M95128-RBN3 The suffix letters and numbers provide specific details about the manufacturing process and packaging: | Code | Meaning | | :--- | :--- | | **M95** | Family (SPI Bus EEPROM) | | **128** | Density (128 Kbit) | | **-R** | Voltage Range (1.8V to 5.5V) | | **BN** | Package (Plastic Dual Flat No-lead / DFN) | | **3** | Temperature Grade (-40°C to +125°C) | --- ### 4. Communication Protocol The M95128 uses a standard SPI protocol (Mode 0 or Mode 3). To read or write, the microcontroller must send an 8-bit instruction followed by a 16-bit address. ```cpp // Example instruction set for M95128 #define WREN 0x06 // Write Enable #define WRDI 0x04 // Write Disable #define READ 0x03 // Read Data from Memory #define WRITE 0x02 // Write Data to Memory #define RDSR 0x05 // Read Status Register ``` --- ### 5. Implementation Considerations 1. **Page Writes:** The device supports "Page Write" mode up to 64 bytes. If you exceed 64 bytes in one write cycle, the address pointer wraps around to the beginning of the page. 2. **Write Cycle Time:** After a write command, the chip requires an internal write cycle (typically 5ms). The microcontroller should poll the **WIP (Write In Progress)** bit in the Status Register before attempting another operation. 3. **Decoupling:** A 0.1µF ceramic capacitor should be placed as close as possible to the VCC and VSS pins to filter high-frequency noise.