EEPROM (Electrically Erasable Programmable Read-Only Memory) is a crucial type of non-volatile memory that retains stored data even when power is removed. These memory chips are extensively used in everyday electronic devices for a variety of purposes. Today, EEPROM has become an indispensable part of our daily lives. Let’s explore Guide to EEPROM further to gain a better understanding of its importance and functionality.

What is EEPROM?

EEPROM, or Electrically Erasable Programmable Read-Only Memory, is a user-modifiable type of ROM―a crucial form of non-volatile memory that allows data to be stored and retained even when power is removed. Unlike standard ROM, EEPROM enables data to be rewritten and erased electrically, making it highly versatile in various electronic applications. It is commonly used in various electronic devices such as computers, Printers, microcontrollers, smart cards, and remote keyless systems.

History of EEPROM

The evolution of EEPROM began in the early 1970s as an advancement over earlier ROM (Read-Only Memory) technologies. It progressed from PROM (Programmable Read-Only Memory) to EPROM (Erasable Programmable Read-Only Memory), and eventually to EEPROM, which fixed the drawbacks of EPROM. Unlike EPROM, which required exposure to UV light for erasure, EEPROM introduced the revolutionary concept of electrically erasing and reprogramming data. 

This technology was first developed by Yasuo Tarui at the Electrotechnical Laboratory in Japan in 1972. Significant advancements in EEPROM technology during the late 1970s improved erasure methods and programming speed, leading to widespread commercial viability by the 1980s. Manufacturers like Intel and Toshiba began producing EEPROM chips, which continued to evolve with higher programming speeds, densities, and reliability. EEPROM also paved the way for more advanced forms of memory such as Flash memory, which offer even greater densities and faster access times while retaining the versatility and significance of EEPROM technology in electronics.

How the EEPROM works?

EEPROM operates based on floating gate transistors. It utilizes electrically programmable floating-gate transistors to store data. Each memory cell in an EEPROM chip contains a floating gate insulated by an oxide layer. Writing data involves applying a high voltage to the control gate, allowing electrons to tunnel through the oxide layer onto the floating gate. This process traps electrons, altering the cell’s charge state to represent binary data (0s and 1s). Reading data is achieved by applying a lower voltage and measuring the resulting current, which indicates the charge state of the cell without altering it. Erasing data involves applying a strong voltage in the opposite direction, causing electrons to tunnel off the floating gate and resetting it to its initial uncharged state. This ability to electrically modify data makes EEPROMs highly versatile and suitable for a wide range of applications. External circuitry controls EEPROMs, managing them for storing small amounts of non-volatile data in applications such as BIOS settings, configuration data, and firmware updates in electronic devices.

Types of EEPROM memory

There are mainly two types of EEPROM memory chips. They are:

  1. Serial EEPROM: Uses a serial interface (typically I2C or SPI) to communicate with microcontrollers or other devices. These chips are denser, cheaper, and can be contained within an eight-pin package. Serial operation transfers data bit by bit, consuming less power and requiring fewer connections, making it ideal for applications where space and power are limited.
  2. Parallel EEPROM: Utilizes a parallel interface, transferring data in parallel over multiple data lines. Parallel EEPROMs are reliable and faster compared to serial EEPROMs but require more I/O pins and more complex circuitry. They are suitable for applications requiring high-speed data access.
Applications of EEPROM

The EEPROM stands as a crucial component in contemporary electronics, enabling devices to store critical data and retains those data even when power is removed. Its versatility and reliability have led to widespread application across various industries. Following are the main applications of EEPROM chips:

  • Used in electronic devices such as routers, modems, printers, and microcontrollers to store configuration settings.
  • Used to store firmware updates and boot configurations. It helps the devices to update its software without requiring hardware replacements.
  • For identification and security. These chips are used in systems requiring unique identification numbers or security keys, such as in smart cards, RFID tags, credit card, cryptographic modules.
  • It can store sensor data or event logs in devices such as data loggers. And the data can be retrieved later for analysis.
  • Found in consumer electronic devices such as TVs, digital cameras and smart appliances to store user settings, playback preferences, operational settings, etc.
  • Mainly used in industrial control systems for storing critical parameters, operational logs, calibration data, etc.
  • In automotive electronics (are electronic systems used in vehicles for various purposes) to store vehicle setting, mileage data, error codes, etc.