The **M95256-RMW3TP/A** is a high-performance, electrically erasable programmable read-only memory (EEPROM) manufactured by **STMicroelectronics**. It is widely used in automotive and industrial applications due to its reliability and high cycle endurance. --- ## 1. Key Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 256 Kbit (32,768 x 8 bits) | | **Interface** | SPI (Serial Peripheral Interface) | | **Max Clock Frequency** | 20 MHz (at 4.5V - 5.5V) | | **Operating Voltage** | 1.8V to 5.5V | | **Package Type** | MLP / DFN8 (2x3 mm) or SO8 (Depending on variant) | | **Temperature Range** | -40°C to +125°C (Grade 3) | | **Endurance** | 4 Million Write Cycles | | **Data Retention** | 200 Years | --- ## 2. Pin Configuration (Typical 8-pin Layout) The device typically follows the standard SPI EEPROM pinout: 1. **S# (Chip Select):** Activates the device when pulled low. 2. **Q (Serial Data Output):** Transfers data out of the device. 3. **W# (Write Protect):** Hardware protection for status registers. 4. **VSS:** Ground. 5. **D (Serial Data Input):** Receives instructions and data. 6. **C (Serial Clock):** Provides timing for data transfer. 7. **HOLD#:** Pauses serial communication without deselecting the device. 8. **VCC:** Supply Voltage. --- ## 3. Core Functional Features ### SPI Protocol Modes The device supports SPI modes 0 (0,0) and 3 (1,1). Data is latched on the rising edge of the clock (C) and shifted out on the falling edge. ### Write Protection - **Software Protection:** Uses a Status Register to define "Block Protect" bits (BP0, BP1) to lock specific quarters or the entire memory array. - **Hardware Protection:** The `W#` pin can be used in conjunction with the Status Register Write Disable (SRWD) bit to lock the status register. ### Page Write Buffer The device features a **64-byte page buffer**, allowing up to 64 bytes to be written in a single internal write cycle (typically 5ms), which significantly improves throughput compared to byte-by-byte writing. --- ## 4. Part Number Breakdown: `M95256-RMW3TP/A` | Suffix | Meaning | | :--- | :--- | | **M95** | SPI Family EEPROM | | **256** | 256 Kbit Density | | **-R** | Low Voltage (1.8V to 5.5V) | | **MW** | Package code (typically SO8 or MLP) | | **3** | Automotive Temperature Grade (-40°C to 125°C) | | **TP** | Tape & Reel Packaging | | **A** | Process Technology identifier (Automotive/Advanced) | ---