## Technical Overview of M95256-RMW3TP The **M95256-RMW3TP** is a high-performance, low-voltage **Serial SPI (Serial Peripheral Interface) EEPROM** (Electrically Erasable Programmable Read-Only Memory) manufactured by STMicroelectronics. It offers 256 Kbits of non-volatile storage. --- ### 1. Key Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 256 Kbits (32,768 x 8 bits) | | **Interface** | SPI (Mode 0 and Mode 3) | | **Clock Frequency** | Up to 10 MHz (at 2.5V - 5.5V) | | **Operating Voltage ($V_{CC}$)** | 1.8V to 5.5V | | **Page Size** | 64 Bytes | | **Endurance** | 4 Million Write Cycles | | **Data Retention** | 200 Years | | **Package Type** | MLP8 (UFDFPN8) or SO8 (The "MW" indicates SO8 Narrow) | --- ### 2. Pin Configuration (SO8 Package) Standard SPI pinouts are used for this device: 1. **S# (Chip Select):** Enables the device when held low. 2. **Q (Serial Data Output):** Transfers data out of the chip during read operations. 3. **W# (Write Protect):** Hardware protection for the status register. 4. **$V_{SS}$:** Ground. 5. **D (Serial Data Input):** Receives instructions and data. 6. **C (Serial Clock):** Synchronizes data movement. 7. **HOLD#:** Pauses serial communication without deselecting the device. 8. **$V_{CC}$:** Supply Voltage. --- ### 3. Electronic Functional Characteristics #### A. Write Protection The device features a flexible protection system: * **Software Protection:** Via the Status Register, allowing the user to protect quarters, halves, or the entire memory array. * **Hardware Protection:** Using the `W#` pin to lock the Status Register bits. #### B. SPI Communication Protocol The M95256-R operates as a slave device. It supports high-speed data transfers via: * **Instruction Set:** Includes `WREN` (Write Enable), `WRDI` (Write Disable), `RDSR` (Read Status Register), `WRSR` (Write Status Register), `READ`, and `WRITE`. * **Clock Polarity:** Compatible with both $CPOL=0, CPHA=0$ and $CPOL=1, CPHA=1$. #### C. Power Management The "R" in the part number signifies a low-voltage range (1.8V to 5.5V), making it ideal for battery-operated devices. It also features a **Standby Mode** where power consumption drops significantly when $S\#$ is high. --- ### 4. Part Number Breakdown | Code | Meaning | | :--- | :--- | | **M95** | Family (SPI Serial EEPROM) | | **256** | Density (256 Kbits) | | **-R** | Operating Voltage (1.8V to 5.5V) | | **MW** | Package (SO8, 150 mil width) | | **3** | Temperature Range (-40°C to +125°C) | | **TP** | Packing (Tape & Reel) | --- ### 5. Application Use-Cases * **Parameter Storage:** Storing calibration data or user settings in industrial equipment. * **Automotive Systems:** Storing configuration logs (given the high temperature rating). * **IoT Devices:** Low-power data logging for sensors.