## Electronic Specifications: M93C66-RMB3G/S The **M93C66-RMB3G/S** is a high-performance, low-voltage serial EEPROM (Electrically Erasable Programmable Read-Only Memory) developed by STMicroelectronics. It is widely used for parameter storage in automotive and industrial applications. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Memory Size** | 4 Kbit (4096 bits) | | **Organization** | Selectable: 256 x 16-bit or 512 x 8-bit | | **Interface** | MICROWIRE (3-wire Serial Interface) | | **Operating Voltage (Vcc)** | 1.8V to 5.5V | | **Clock Frequency** | 2 MHz (@ 4.5V - 5.5V) | | **Package Type** | UFDFPN8 (Thin Dual Flat No-lead, 2x3 mm) | | **Temperature Range** | -40°C to +125°C (Automotive Grade 3) | | **Write Cycles** | 4 million cycles | | **Data Retention** | 200 Years | --- ### 2. Functional Description The device operates using the **MICROWIRE** protocol, which is a subset of the SPI interface. It is designed for applications where power consumption and space are critical constraints. #### Pin Configuration (UFDFPN8) * **S (Chip Select):** Activates the device when held high. * **D (Serial Data Input):** Used to transfer opcodes, addresses, and data. * **Q (Serial Data Output):** Used to read data out of the device. * **C (Serial Clock):** Synchronizes the communication. * **ORG (Organization):** Determines if the memory is structured as 8-bit or 16-bit. * **Vcc/Vss:** Power supply and Ground. --- ### 3. Part Number Breakdown Understanding the suffix codes is essential for sourcing and PCB design: * **M93C66:** Base part number (4 Kbit MICROWIRE EEPROM). * **-R:** Operating voltage range (1.8V to 5.5V). * **MB:** Package code for **UFDFPN8** (2x3 mm). * **3:** Device Grade (Automotive temperature range -40°C to +125°C). * **G:** ECOPACK2 (RoHS compliant, Halogen-free). * **S:** Likely refers to a specific manufacturing process or customer-specific screening. --- ### 4. Implementation Example (Basic Logic) To read from the memory, the microcontroller must send a specific bit sequence. Below is a conceptual representation of a Read instruction: ```c // Example bit sequence for a Read operation (16-bit mode) // Start Bit (1) | Opcode (10) | Address (A7-A0) // Total 11 bits sent to initiate a read. void read_eeprom(uint8_t address) { digitalWrite(CHIP_SELECT, HIGH); shiftOut(DATA_IN, CLOCK, MSBFIRST, 0x06); // Start + Read Opcode shiftOut(DATA_IN, CLOCK, MSBFIRST, address); uint16_t data = shiftIn(DATA_OUT, CLOCK, MSBFIRST); digitalWrite(CHIP_SELECT, LOW); } ``` ---