Electrically Erasable Programmable Read-Only Memory

What does Electrically Erasable Programmable Read-Only Memory mean?

Electrically Erasable Programmable Read-Only Memory (EEPROM) is a type of non-Volatile Memory that combines properties of both ROM (read-only memory) and RAM (Random Access memory). It allows the user to erase and rewrite data electrically, without the need for ultraviolet light like in EPROM (erasable programmable read-only memory).

EEPROM consists of an array of floating-gate transistors. Each transistor’s floating gate is an isolated electrode in the gate oxide. When a high voltage is applied to the control gate, electrons can tunnel through the gate oxide and become trapped on the floating gate. This trapped charge alters the threshold voltage of the transistor, affecting its conductivity.

Data is written to EEPROM by selectively charging the floating gates of the transistors. By applying the appropriate voltage sequence, electrons can be trapped or released from the floating gates, changing the transistor’s state and thus the stored data. Data is erased by exposing the memory to a high voltage, which discharges the floating gates.

EEPROM has a finite endurance, meaning it can only be written to a limited number of times before the transistors degrade. However, it offers excellent data retention, with data being able to be stored for over ten years without significant loss.

Applications

EEPROM finds applications in various technologies:

• Configuration settings: EEPROM is used to store configuration settings for devices, such as the BIOS settings in computers and the presets on digital cameras.
• Program code: EEPROM can store program code, particularly for embedded systems where the code needs to be updated or changed infrequently.
• Data logging: EEPROM is used in data loggers to store measured data over time.
• Security: EEPROM can store Encryption keys and other sensitive information securely.
• Consumer electronics: EEPROM is found in consumer electronics such as remote controls and game consoles to store user preferences and game progress.

EEPROM’s versatility and non-volatile nature Make it a valuable component in modern electronic devices.

History

The development of EEPROM started in the 1970s, with George Perlegos of Intel inventing the first EEPROM in 1978. Perlegos’s design was based on a floating-gate transistor, which could be charged or discharged by applying a high voltage across the gate.

Early EEPROM devices had limited write endurance, with cells only capable of being written to a few hundred times. However, advancements in process technology and materials have increased the write endurance of modern EEPROM devices to millions of write cycles.

Over the years, EEPROM has undergone significant miniaturization, with the development of smaller and more efficient memory cells. This has enabled the widespread adoption of EEPROM in various electronic devices.