The **M93C66-RMB7G** is a specific variant of a serial Microwire EEPROM (Electrically Erasable Programmable Read-Only Memory). It is manufactured by STMicroelectronics and is commonly used for non-volatile data storage in consumer and industrial electronics. ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 4 Kbit (4096 bits) | | **Memory Organization** | 256 x 16-bit or 512 x 8-bit (Selectable) | | **Interface** | Microwire (3-wire Serial Interface) | | **Operating Voltage** | 1.8V to 5.5V | | **Clock Frequency** | 2 MHz (at 5V), 1 MHz (at 1.8V) | | **Package Type** | UFDFPN8 (Ultra-thin Fine pitch Dual Flat No-lead) | | **Operating Temperature** | -40°C to +105°C (Automotive Grade 2) | | **Endurance** | 4 million write cycles | | **Data Retention** | 200 years | --- ### 2. Part Number Breakdown: `M93C66-RMB7G` Understanding the suffix is critical for identifying the physical and electrical characteristics: * **M93C66**: The base model (4 Kbit Microwire EEPROM). * **-R**: Indicates a supply voltage range of **1.8V to 5.5V**. * **MB**: Represents the **UFDFPN8** package (2x3 mm). * **7**: Indicates the temperature range (**-40°C to +105°C**). * **G**: Indicates **ECOPACK2** (RoHS compliant, Halogen-free). --- ### 3. Pin Configuration (UFDFPN8) | Pin Number | Name | Description | | :--- | :--- | :--- | | 1 | **S** | Chip Select (Active High) | | 2 | **C** | Serial Clock | | 3 | **D** | Serial Data Input | | 4 | **Q** | Serial Data Output | | 5 | **Vss** | Ground | | 6 | **ORG** | Organization Select (High: x16, Low: x8) | | 7 | **DU/WC** | Do Not Use / Write Control | | 8 | **Vcc** | Supply Voltage | --- ### 4. Distinctive Features * **Microwire Protocol**: Unlike I2C or SPI, Microwire uses a specialized 3-wire protocol (plus Chip Select) that is synchronous and full-duplex. * **Hardware Write Protection**: Some variants allow for protecting data against accidental write instructions using specific pin configurations. * **Self-Timed Programming**: The device handles the internal write cycle automatically, notifying the host via the Ready/Busy status on the `Q` pin. * **Low Power Consumption**: Designed for battery-operated devices, with very low standby current. --- ### 5. Common Applications * **Calibration Data**: Storing sensor offset values and calibration constants. * **Device Configuration**: Saving user settings, ID numbers, or MAC addresses. * **Automotive Modules**: Used in instrument clusters and engine control units due to the high-temperature rating. * **Consumer Electronics**: Storing firmware parameters in small handheld devices.