EEPROM 24C04

Description

The 24C04 is a 4-kilobit (512-word x 8-bit) Serial EEPROM. Like the 24C16, it is designed with a unique internal structure that utilizes the slave address bits to manage the memory capacity, making it a “mid-sized” non-volatile memory solution.

Key Specifications

• Capacity: 4K bits (512 bytes)

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

• Operating Voltage: 1.7V to 5.5V

• Write Cycle Time: $\le 5\text{ms}$

• Endurance: 1,000,000 write cycles

• Page Size: 16 bytes

Pinout Configuration (8-Pin)

1. A0: Internally Unconnected (NC) or ignored.

2. A1: Device Address Input (sets the 2nd bit of the slave address).

3. A2: Device Address Input (sets the 3rd bit of the slave address).

4. VSS: Ground.

5. SDA: Serial Data I/O.

6. SCL: Serial Clock Input.

7. WP: Write Protect.

8. VCC: Power Supply.

Addressing and Memory Blocks

The 24C04 is organized into two 256-byte blocks. Because of this, it uses a slightly different addressing approach than the 24C02:

• Block Select: The device address byte includes a bit (often referred to as $P0$ or $B0$) that selects between the first 256 bytes (Block 0) and the second 256 bytes (Block 1).

• Flexibility: Unlike the 24C16, the 24C04 still allows for some device selection via the A1 and A2 pins. This means you can typically have up to 4 of these devices on the same $I^2C$ bus.

Comparison Table

Common Applications

• Configuration Storage: Ideal for devices needing slightly more space than a 24C02, such as more complex calibration profiles.

• Event Logging: Storing limited history of device usage or error codes.

• Parameter Sets: Holding multiple “modes” of operation for microcontroller-based systems.

Essential Design Requirements

• Pull-up Resistors: SDA and SCL pins are open-drain and require $4.7\text{k}\Omega$ to $10\text{k}\Omega$ pull-up resistors to VCC.

• Decoupling: Use a $0.1\mu\text{F}$ capacitor between VCC and VSS to ensure stable power delivery, which is vital during the sensitive “Write” cycle.

• Write Protect (WP): To enable normal operation, connect the WP pin to ground. If the pin is left floating, behavior can be unpredictable, so a hard connection is always best.