AT24C256 I2C Interface EEPROM Memory Module

AT24C256 I2C Interface EEPROM Memory Module provides non-volatile, reliable external data storage for embedded microcontrollers and industrial control systems. This breakout board integrates the Microchip AT24C256 serial EEPROM, which organizes 256 Kbits (32,768 bytes) of storage into an accessible 2-wire I2C interface. Consequently, engineers can retain critical system parameters, calibration tables, and sensor logs even during sudden power interruptions. Furthermore, onboard address jumpers allow you to connect up to four modules on a single I2C communication bus without signal collisions. Therefore, developers can expand system memory capacity effortlessly with minimal microcontroller I/O pin consumption.

Key Features:

• High Memory Density: Provides 256 Kilobits (32 KB) of non-volatile EEPROM storage organized into 512 pages of 64 bytes each.
• Two-Wire Serial Interface: Utilizes standard I2C protocol, saving valuable GPIO pins on host microcontrollers like Arduino, STM32, and ESP32.
• Hardware Address Selection: Features onboard A0 and A1 jumper pads; consequently, you can cascade up to four modules on the same serial bus.
• Exceptional Endurance: Guarantees 1,000,000 write cycles and 100-year data retention, ensuring long-term operational integrity.
• Integrated Pull-Up Resistors: Incorporates onboard I2C pull-up resistors to streamline plug-and-play prototyping.
• Hardware Write Protection: Offers a dedicated WP pin so that you can protect stored parameters against unintended write operations.

Technical Specifications:

• Operating Voltage: 2.7 V to 5.5 V DC
• Interface Bus: I2C (Inter-Integrated Circuit)
• Clock Frequency: 400 kHz (Fast Mode) at 5 V; 1 MHz (Fast Mode Plus) supported by core IC
• Memory Capacity: 256 Kbits (32,768 × 8 bits)
• Page Write Buffer: 64 Bytes
• Write Cycle Time: ≤ 5 ms (byte or page write)
• Active Read Current: ≈ 1 mA (Typical at 5 V)
• Standby Current: ≤ 3 μA at 5 V
• Operating Temperature: -40°C to ±85°C

Mechanical Specifications:

• Core Chipset: Microchip AT24C256 / AT24C256C (SOIC-8 footprint)
• PCB Material: High-grade FR-4 double-sided fiberglass board
• Pin Pitch: Standard 2.54 mm (0.1 inch) breadboard-compatible headers
• Mounting Support: Dual mounting holes for secure industrial chassis installation

Dimensions:

• Module Length: ≈ 36.5 mm
• Module Width: ≈ 12 mm
• Module Height: ≈ 10 mm (including standard male headers)
• Mounting Hole Diameter: ≈ 3 mm
• Net Weight: ≈ 3 g

Pinout and Wiring:

• VCC: Connect to DC power supply positive rail (3.3 V or 5.0 V).
• GND: Connect to common system ground.
• SCL: Connect to microcontroller I2C Serial Clock line; however, verify that bus pull-up voltages match logic levels.
• SDA: Connect to microcontroller I2C Serial Data line for bidirectional transmission.
• WP: Connect to VCC to enable full write protection, or tie to GND to allow normal read/write cycles.
• A0, A1: Configure onboard solder pads to set the physical I2C device address (0x50 to 0x53).

Datasheet Reference:

• Download Microchip AT24C256C Datasheet

Commonly Used in:

• Arduino and Raspberry Pi Development: Expanding flash-constrained development boards with persistent external storage.
• Industrial Automation Controllers: Storing configuration states, recipe parameters, and machine runtime metrics safely.
• Smart Energy Meters: Recording periodic electricity, gas, or water usage statistics reliably.

Applications:

• Environmental Data Loggers: Storing temperature, humidity, and atmospheric readings before bulk network transmission.
• Robotics Calibration: Retaining PID loop gains, servo trim values, and sensor offset maps across boot cycles.
• Access Control Systems: Managing RFID tag credentials and entry timestamps securely inside offline door controllers.

Equivalent Models:

• 24LC256: Standard Microchip pin-compatible alternative operating across 2.5 V to 5.5 V.
• CAT24C256: Onsemi equivalent 256 Kb serial I2C CMOS EEPROM offering identical pinouts.
• M24256: STMicroelectronics 256 Kbit I2C EEPROM compatible with standard industrial firmware libraries.

Package Includes:

• 1 x AT24C256 I2C Interface EEPROM Memory Module