I²C EEPROM Selection: 24Cxx Densities, Wiring & FT24C Replacement
The 24Cxx family of I²C EEPROMs is the most common small non-volatile memory. This article covers density naming, wiring and addressing, and how FMD's FT24C series replaces AT24C / 24LC / M24C parts.
What an I²C EEPROM is and how 24Cxx is named
An EEPROM is electrically erasable non-volatile memory, often used to store configuration, calibration, or serial numbers. The 24Cxx is the industry-standard I²C EEPROM family, where the number is the density in kbit: 24C02 = 2Kbit, 24C16 = 16Kbit, 24C64 = 64Kbit, 24C256 = 256Kbit, and so on.
It reads and writes over just the two I²C wires (SCL/SDA), with a minimal pinout and low cost — a staple of embedded design.
Wiring and addressing
A standard 8-pin part wires up as VCC, GND, SCL, SDA, plus the A0/A1/A2 device-address pins and a WP write-protect pin. SCL/SDA need pull-up resistors (commonly 4.7k).
A0–A2 let you put several EEPROMs on one I²C bus (up to 8 for smaller densities); pulling WP high prevents accidental writes. Larger densities (e.g. 24C256) use more internal address bits, so the device count and addressing rules differ slightly — follow the datasheet.
FT24C as a replacement for AT24C / 24LC / M24C
FMD's FT24C series uses the standard 24Cxx I²C interface and common pinout (SOP8 / TSSOP8 / DIP8), as a drop-in for popular parts like Microchip AT24C / 24LC and ST M24C, with a wide 1.8V ~ 5.5V supply, >1,000,000 write cycles, and >100-year data retention.
When switching, confirm the voltage range, page-write size (commonly 8–64 bytes depending on density), and write-cycle time match your original design.
Density mapping and sourcing
FT24C densities follow the industry naming — e.g. FT24C02 ↔ 24C02 (2Kbit), FT24C256 ↔ 24C256 (256Kbit), spanning 2K to 256Kbit.
JLink Technology is an authorized FMD distributor supplying the full FT24C I²C EEPROM line. Send us your current 24Cxx part number and volume, and we will match the corresponding FT24C device and reply with stock, pricing, and lead time.
Products mentioned
FT24C Series I²C EEPROM (2K ~ 256K bit)
The FT24C series are standard I²C serial EEPROMs spanning 2K to 256K bit (FT24C02 ~ FT24C256), compatible with industry-standard pinouts, with a wide 1.8V ~ 5.5V supply — widely used to store configuration parameters, calibration data, and serial numbers.
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