The AT24C02 is a serial EEPROM chip produced by Microchip Technology (formerly Atmel Corporation). EEPROM is a type of non-volatile memory that allows users to program and erase the data it stores. AT24C02 belongs to the AT24C series and is a member of it.

AT24C02 is a 2K-bit serial CMOS E2PROM, containing 256 8-bit bytes. It uses advanced CMOS technology to greatly reduce the power consumption of the device.

AT24C02 has a 16-byte page write buffer. This device uses the IIC bus as its working mode and has a special write protection function.

Ⅰ.Functions of AT24C02

•AT24C02 supports I2C, bus data transfer protocol I2C, the bus protocol stipulates that any device that transmits data to the bus acts as a transmitter.
•Any device that receives data from the bus is a receiver. Data transfer is controlled by the master device that generates the serial clock and all start and stop signals.
•Both the master device and the slave device can serve as transmitters or receivers, but the master device controls the mode of transmitting data (sending or receiving). Since A0, A1 and A2 can form eight situations from 000 to 111, that is, input through the device address Terminals A0, A1 and A2 can connect up to 8 AT24C02 devices to the bus and select the device through different configurations.

Ⅱ.Specification parameters of AT24C02

•Installation style:Through Hole
•Storage capacity:2 kbit
•Package/Case:PDIP-8
•Organization:256x8
•Interface type:2-Wire, I2C
•Power supply voltage-Minimum:1.7V
•Power supply voltage-Max:3.6V
•Maximum clock frequency:1MHz
•Minimum operating temperature:-40℃
•Maximum operating temperature:+85℃
•Maximum clock frequency:1MHz
•Supply current—max:1 mA
•Data retention:100 Year
•Access time:450 ns
•Operating power supply voltage:1.7V to 3.6V

Ⅲ. Pin configuration of AT24C02

•A0-A2:Address input
•SDA:serial data
•SCL:serial clock input
•WP:Write Protect
•NC:No Connect
•GND:Ground
•VCC:power supply

Pin description:

•SERIAL DATA(SDA): The SDA pin is bidirectional and is used for serial data transmission.

•SERIAL CLOCK(SCL): The SCL input is used to input positive edge clock data to each EEPROM device and output negative edge clock data to each device.

•DEVICE/PAGE ADDRESSES(A2.A1.A0): The A2, A1 and AO pins are the device address inputs of the hardwired AT24C02. Up to 8 1K/2K devices can be addressed on a bus system.

•WRITE PROTECT(WP):AT24C02 has a write protect pin to provide hardware data protection. When connected to ground (GND), the write-protect pin allows normal read/write operations. When the pin is connected to VCC, the Write protection feature is enabled and writing is not allowed.

Ⅳ.Correctly connect AT24C02 to the microcontroller or other main control device

1.I2C bus connection:
•AT24C02 uses the I2C bus for communication, so SDA (data line) and SCL (clock line) need to be connected.
•Connect the SDA pin of the AT24C02 to the SDA pin of the I2C bus of the microcontroller or master device.
•Connect the SCL pin of AT24C02 to the SCL pin of the I2C bus of the microcontroller or master device.

2.Power connection:
•Connect the VCC pin of AT24C02 to the positive power supply of the microcontroller or host device.
•Connect the GND pin of AT24C02 to the power ground of the microcontroller or host device.

3.Power and signal level matching:
•Make sure that the power supply levels of the microcontroller and AT24C02 match, and that the signal levels on the I2C bus also match.

4.Address settings:
•AT24C02 allows multiple devices to be connected to the same I2C bus, and different devices can be distinguished by setting their addresses.
•AT24C02 has a 7-bit address which can be set by connecting the A0, A1 and A2 pins to VCC or GND.
•Consult the AT24C02 data sheet to determine the required address settings and connect the A0, A1 and A2 pins accordingly.

Ⅴ.DC characteristics of AT24C02

Ⅵ.Application fields of AT24C02

1.Sensor data storage: AT24C02 is a serial EEPROM memory, which is often used to store non-volatile data. In sensor network and Internet of Things applications, AT24C02 is often used to store sensor data, device status and other related information due to its large storage capacity, small size and high reliability. For example, in applications such as temperature sensors and humidity sensors, these sensors may periodically collect environmental data (such as temperature and humidity) and then store this data in the AT24C02. When you need to view or analyze these data, you can obtain it by reading the content in AT24C02. In order to realize the storage and reading of data, it is usually necessary to design a microcontroller (such as Arduino or Raspberry Pi, etc.) to communicate with the AT24C02. The microcontroller can read the sensor's data and then store this data in the AT24C02, or read previously stored data from the AT24C02.

2.Smart cards and security modules: Due to its small package and relatively low power consumption, the AT24C02 can also be used to store key information in smart cards and security modules, such as authentication keys, encryption keys, etc. In smart cards, AT24C02 can be used to store important information such as user authentication keys, private keys, certificates, etc. When performing identity verification or performing security operations, the smart card can perform corresponding operations by reading the data in AT24C02. In the security module, AT24C02 can also be used to store important information such as encryption keys and security protocol parameters. This information can be used to securely communicate between devices, protecting the confidentiality and integrity of data.

3.Embedded system storage: AT24C02 is usually used in embedded systems, such as microcontrollers, microcontrollers and embedded microprocessors, as non-volatile memory to store system parameters, configuration information, calibration data, etc. Embedded systems usually need to store some fixed parameters, such as the unique identifier of the device, hardware version, firmware version, etc. AT24C02 can provide non-volatile storage to ensure that these parameters are still available after power failure or restart. Embedded systems usually need to read configuration information at startup, such as communication protocol settings, peripheral initialization parameters, etc. AT24C02 can be used to store these configuration information so that the system can be restored to the predetermined working state after restarting.

4.Electronic device configuration: Since AT24C02 is a small-capacity memory, it is often used to store configuration information of electronic devices, such as the configuration of LCD displays, parameters of communication equipment, etc.

5.Automotive electronic system: AT24C02 can be used to store vehicle configuration information, such as seat adjustment settings, door locking and unlocking preferences, etc. This information can remain unchanged after a power outage, ensuring that the user's personalized settings are not lost. A car's ECU typically monitors and records fault codes for various vehicle systems. By storing the history of fault codes in AT24C02, even if the vehicle is turned off, the fault code information can be retained to facilitate vehicle maintenance and diagnosis.

6.Instrument storage: Many instruments require regular calibration to ensure the accuracy of measurement results. The AT24C02 can be used to store this calibration data so that it can be accessed and updated when needed. Instrumentation often provides various user-configurable settings such as display units, measurement ranges, alarm thresholds, etc. The AT24C02 can be used to store these user settings, ensuring they are not lost after a power outage. Some instruments may need to record historical data or operation logs so that users can view the usage history of the instrument. The AT24C02 provides a small non-volatile memory space suitable for storing these limited historical records.

7.Small device storage: Smart home devices (such as smart light bulbs, smart sockets, smart door locks, etc.) usually need to store the device's configuration information, such as device name, networking credentials, etc. The AT24C02 can be used to retain this configuration information after a power outage or reboot. Small sensor devices, such as temperature sensors and humidity sensors, may need to store historical measurement data or device calibration information. The AT24C02 can provide sufficient storage capacity to cope with these needs.

Ⅶ.Structure and addressing of AT24C02

The storage capacity of AT24C02 is 2K bit, and the content is divided into 32 pages, each page is 8Byte, totaling 256Byte. There are two addressing methods during operation: chip addressing and on-chip sub-address addressing.

1.Chip addressing: The chip address of AT24C02 is 1010, and its address control word format is 1010A2A1A0R/W. Among them, A2, A1, and A0 are programmable address selection bits. After the A2, A1, and A0 pins are connected to high and low levels, a determined three-digit code is obtained, which together with 1010 forms a 7-bit code, which is the address code of the device. R/W is the chip read and write control bit. If this bit is 0, it means the chip is performing a write operation.

2.On-chip sub-address addressing: Chip addressing can perform read/write operations on any one of the internal 256B. Its addressing range is 00~FF, with a total of 256 addressing units.

Ⅷ.T24C02 alternative model

1.ON Semiconductor CAT24C02: ON Semiconductor’s CAT24C02 is another similar I2C EEPROM suitable for similar application scenarios.

2.Microchip 24C02: Microchip Technology inherited Atmel’s product line, so Microchip’s 24C02 is a direct replacement for AT24C02.

3.STMicroelectronics M24C02: The M24C02 produced by STMicroelectronics is also a 2K-bit (256 bytes) EEPROM chip on the I2C bus and can be used as a replacement for AT24C02.

4. Maxim Integrated DS2432: Maxim Integrated's DS2432 is an EEPROM with a 1-Wire interface, suitable for one-wire bus applications.

Frequently Asked Questions

1.Can the AT24C02 be used for both read and write operations?
Yes, the AT24C02 supports both read and write operations, making it suitable for storing and retrieving data.

2.How many bits are used for the device address in the I2C communication of AT24C02?
The I2C address of the AT24C02 is 7 bits long.

3.What is the function of AT24C02?
The AT24C02 is a non-volatile memory, meaning it can retain stored data after a power outage or restart. This makes it ideal for storing critical configuration information, calibration data, user settings, etc., ensuring that this data is not lost after a power outage.