EEPROM 24C02

Description

The 24C02 is a widely used 2-kilobit (256-word x 8-bit) Serial Electrically Erasable and Programmable Read-Only Memory (EEPROM). It is organized as 32 pages of 8 bytes each and is typically used to store small amounts of configuration data, calibration values, or system settings that need to be retained even when power is removed.

Key Specifications

• Capacity: 2K bits (256 bytes)

• Interface: $I^2C$ (2-wire serial protocol)

• Operating Voltage: Typically 1.7V to 5.5V

• Write Cycle Time: $\le 5\text{ms}$

• Endurance: 1,000,000 write cycles

• Data Retention: $> 100$ years

• Package Types: DIP-8, SOIC-8, TSSOP-8

Pinout Configuration (8-Pin DIP/SOIC)

1. A0, A1, A2: Device Address inputs (used to set the $I^2C$ address).

2. VSS: Ground.

3. SDA: Serial Data I/O.

4. SCL: Serial Clock Input.

5. WP: Write Protect (connect to VCC to disable writing, GND to enable).

6. VCC: Power Supply.

Communication Basics

The 24C02 uses the standard $I^2C$ protocol, meaning it requires only two pins (SDA and SCL) to communicate with a microcontroller.

• Addressing: The device has a 7-bit slave address. The first four bits are fixed (1010), and the next three bits are determined by the status of the A0, A1, and A2 pins. This allows you to connect up to eight 24C02 chips on the same $I^2C$ bus.

• Read/Write Operations:

  • Byte Write: The master sends the address and the data byte, followed by a stop condition.

  • Page Write: The 24C02 allows writing up to 8 bytes in a single cycle to speed up data storage.

  • Random Read: Allows the master to read any specific memory location.

Common Applications

• Configuration Storage: Storing user settings like display brightness, volume levels, or radio station presets.

• Calibration Data: Storing sensor offset or sensitivity values for precision instruments.

• Identification: Storing serial numbers or MAC addresses.

Essential Design Requirements

• Pull-up Resistors: The $I^2C$ bus (SDA and SCL) requires external pull-up resistors (typically $4.7\text{k}\Omega$ to $10\text{k}\Omega$) connected to VCC, as the bus pins are open-drain.

• Decoupling: Always place a $0.1\mu\text{F}$ ceramic capacitor as close as possible to the VCC and VSS pins to minimize noise and ensure data integrity during writes.

• Write Protect (WP): If your application requires the memory to be read-only, ensure the WP pin is tied to VCC. If you leave it floating, it might behave inconsistently; it is best to tie it to GND for normal read/write operations.