Microchip 24FC1025-I/SN 1024K I2C Serial EEPROM: Features and Application Design Guide
The Microchip 24FC1025-I/SN is a high-density, 1-Megabit (1024 Kbit) serial Electrically Erasable Programmable Read-Only Memory (EEPROM) that utilizes the ubiquitous I2C (Inter-Integrated Circuit) protocol for communication. This device is engineered for applications requiring non-volatile data storage with high reliability, low power consumption, and a compact footprint. Its 128K x 8 memory organization makes it suitable for storing large datasets, configuration parameters, and event logs in a wide array of systems.
Key Features and Specifications
The 24FC1025 distinguishes itself with a robust set of characteristics designed for modern electronic design:
High-Density Memory: Offers 1,048,576 bits of memory organized as 131,072 words of 8 bits each, providing ample space for complex applications.
I2C Serial Interface: Supports a two-wire serial interface (SDA and SCL), significantly reducing board space and interconnect complexity compared to parallel memory solutions. It is compatible with both standard (100 kHz) and Fast-mode (400 kHz) operations.
Advanced Hardware Data Protection: Features a hardware write-protect (WP) pin. When asserted, this pin prevents any write operations to the entire memory array, safeguarding critical data from accidental corruption.
Page Write Operation: Supports 128-byte page write mode, allowing for more efficient programming of sequential data blocks and reducing total write time.
Wide Voltage Operation: Operates across a broad voltage range (1.7V to 5.5V), making it compatible with various logic levels and ideal for both 5V and low-power 3.3V systems.
High Reliability: Endures over 1 million erase/write cycles per byte and offers data retention greater than 200 years, ensuring long-term data integrity.
Extended Temperature Range: The -I/SN suffix denotes operation over the industrial temperature range (-40°C to +85°C), suitable for harsh environments.
Packaging: Available in the space-saving 8-lead SOIC (SN) package.
Application Design Guide
Integrating the 24FC1025 into a system requires careful consideration of the I2C protocol and the device's specific operational nuances.
1. Circuit Connection:
The device typically requires only four connections to a microcontroller: VCC (power supply), GND (ground), SDA (Serial Data), and SCL (Serial Clock). The WP pin must be tied to GND for write enable or to VCC for write protection. The A0, A1, and A2 address pins are not used for device addressing in the 24FC1025 and can be left floating or tied to ground, as its address is fixed internally.
2. Device Addressing:
Following a Start condition, the master must initiate a control byte. The 24FC1025 has a predefined 7-bit slave address of 1010xxx(b), where the three least significant bits (xxx) are determined by the memory block address (see point 3). The eighth bit of the control byte specifies a read (1) or write (0) operation.
3. Memory Addressing and Paging:
To access the full 1Mb memory, a 16-bit (2-byte) word address is required. The 24FC1025 internally divides its memory into two 512Kbit blocks. The Most Significant Bit (MSB) of the word address is effectively used to select between these two blocks. This is handled by sending the two address bytes after the control byte. Designers must ensure their I2C driver can handle this 2-byte address pointer.
4. Write Cycle Timing:
After transmitting the address and data bytes, the device initiates an internal tWR (Write Cycle Time) to program the memory. During this time (max 5ms), the device will not acknowledge its slave address (polling is required to know when the write cycle is complete). It is critical to observe the page write boundaries; attempting to write more than 128 bytes within a single page will cause the address pointer to wrap around and overwrite previously written data in that page.
5. Noise and Signal Integrity:
As with any I2C bus, pull-up resistors on both the SDA and SCL lines are mandatory. Their value must be chosen to provide adequate rise times according to the bus speed while limiting current consumption. For long cables or noisy environments, ensuring clean signal integrity is paramount.
Typical Applications
This EEPROM is ideal for use in:
Data logging systems in industrial automation.
Storage of configuration and calibration data in medical devices.
Parameter storage in smart meters and automotive subsystems.
Firmware and program storage in consumer electronics.
ICGOODFIND: The Microchip 24FC1025-I/SN is a premier solution for designers seeking high-density, reliable non-volatile memory with the simplicity of the I2C bus. Its combination of advanced hardware protection, low-power operation, and industrial-grade robustness makes it an excellent choice for demanding applications across numerous industries.
Keywords: I2C EEPROM, Non-volatile Memory, Hardware Write Protection, Page Write, Industrial Temperature Range
