What is the full form of EEPROM

EEPROM: Electrically Erasable Programmable Read-Only Memory

EEPROM stands for Electrically Erasable Programmable Read-Only Memory. EEPROM is a form of non-volatile memory integrated into microcontrollers for smart cards, remote keyless devices, and different electronic or computational devices. It is employed to store relatively small quantities of data and allows individual bytes to be deleted and reprogrammed.

EEPROM is a modified variant of EPROM (Erasable Programmable Read-Only Memory) that employs electrical signals instead of UV signals, formerly utilised in EPROM, to erase and rewrite the program or the data. Computers mainly utilise it as a chip for storing digital data.

Arrays of floating-gate transistors make up EEPROMs. EEPROMs can be programmed and deleted in-circuit using specific programming signals. EEPROMs could only perform single-byte operations initially, which made them slow; however, more recent EEPROMs support multi-byte page operations.

The longevity of an EEPROM is due to an important design factor in an EEPROM that is regularly reprogrammed. A contemporary EEPROM can now erase and reprogram an object up to one million times before needing to be replaced.

It is a chip that can be rewritten and holds data without power. Although byte-addressable, EEPROMs must first be erased to be rewritten. Circuit boards frequently use EEPROMs for storing small amounts of data and instructions. It has a lengthy lifetime (typically 1,000,000 cycles) and smaller erasable blocks (as little as a single byte).

George Perlegos created EEPROM at Intel in 1978. Being a non-volatile memory, it preserves all the information even when the power is off and can store more data or bits than earlier EPROMs. In newer versions, it serves as flash memory and holds the computer's BIOS.

Flash memory is a form of EEPROM created for great speed and high density at the expense of huge erase blocks (usually 512 bytes or bigger) and a finite quantity of write cycles (often 10,000). Numerous microcontrollers have both: a tiny EEPROM for parameters and flash memory for the firmware.

Wherever a system needs a sizable volume of non-volatile solid-state storage, flash memory is the preferred memory option since it is considerably less expensive than byte-programmable EEPROM. EEPROMs are still common in programs like SPD (Serial Presence Detect) that need minimal storage capacity.

Presently, EEPROM is employed in both regular electronic devices and embedded microcontrollers. Various security devices utilise EEPROM technology, including credit cards, SIM cards, keyless entry, etc.

Pros of EEPROM

Some of the positives of EEPROM are listed below:

• Data can be quickly erased since it employs electrical signals and has the option of erasing either full contents or a specific byte.
• Data stored in EEPROM is non-volatile and remains intact even when the power is turned off.
• It is easy to reprogram, which can be done without removing it from the computer and without additional equipment.
• EEPROM erases content electronically in 5-10 ms as opposed to EPROM, which uses UV signals and erases memory in minutes.

Cons of EEPROM

Some of the negatives of EEPROM are listed below:

• Problems with data retention because the used insulator isn't a perfect insulator, and the manufacturer only guarantees data retention for ten years.
• Different voltages are needed for viewing, writing, and deleting the material.

Transistors for EEPROM

In EEPROM, metal-oxide-silicon (MOS) transistors are used to delete the charge while floating gate or storage transistors maintain the charge. Bit cells built on complementary MOS technology make up floating gate transistors (FGTs). When the control gate receives a pulse, current flows even while the floating gate is uncharged. The transistor is now operating normally.

When the gate is charged, it hinders or inhibits the operation of the control gate, which causes the current to stop flowing. The source and drain terminals must be grounded in order for the floating gate to charge, and the control gate tunnel must receive enough voltage to pass through the oxide.

The trapped electrons in the gate decide whether the gate is in a charged or uncharged state, which then decides whether the gate contains a 0 or a 1. The charge dissipates into the substrate as a result of a reverse voltage being transmitted from another transistor, clearing it.

EEPROM memory types

EEPROM memory chips come in two different varieties.

1. Serial EEPROM

In comparison to parallel EEPROM chips, serial EEPROM chips are denser since they may fit into a compact eight-pin package. Moreover, serial chips are less costly. Data is sent serially and moves slowly, which is a downside. Their operations are also more complicated.

With serial EEPROM, a variety of standard interface types are available:

• Microwire Inter-Integrated Circuit
• Serial Peripheral Interface
• UNI/O
• 1-Wire

For the purpose of functioning, each of these interfaces needs one to four control signals.

The three steps of the EEPROM serial protocol are as follows:

• Phase of operation
• Phase of address
• Phase of data

2. EEPROM in parallel

Both flash memory and EPROM devices can use the parallel EEPROM chip. Compared to the serial EEPROM method, it has a quicker and more reliable data transfer mechanism. Its size, density, and price are all higher due to the higher pin count. Because of these factors, flash memory or serial EEPROM is more commonly utilised than parallel EEPROM.

Modes of EEPROM failure

EEPROM chips are not completely fail-safe, much like any other electrical and computing equipment. There are two main ways that EEPROM chips might malfunction.

1. Data persistence

The bit cells in EEPROM become trapped in the programmed state during rewrite operations. This occurs as a result of trapped electron accumulation in the FGT. The threshold for the "zero state" cannot be identified when more electrons become trapped, leaving the cells permanently in the programmed state and perhaps leading to chipping failure. Because of this, EEPROM manufacturers state the required minimum and maximum rewrite cycles.

2. Data storage duration

The EEPROM architecture is designed to permit electrons to drift across the imperfect insulator after being injected into the floating gate. Due to this floating, some charge is lost, which causes some data to be deleted and the memory cell to return to its previously erased condition.

Manufacturers provide a restricted data retention term of a set number of years, such as 10, as a result. Temperature and other environmental conditions can potentially shorten the EEPROM's data retention period.

Flash memory and EEPROM

A unique kind of EEPROM is flash memory. Flash memory chips, which are structurally identical to EEPROM, use standard PC voltages for erasure and reprogramming. Moreover, a whole block of bytes needs to be cleared first.

A single standard MOS transistor is used in flash memory to erase an entire block of FGTs. One MOS transistor is typically present for every eight FGTs in EEPROMs. The MOS transistor deactivates the charge while the FGT maintains it.

Flash memory modules nowadays are capable of storing gigabytes and even more data, making them ideal for cameras and computers. This information may be semi-static or static. On circuit boards, however, standard EEPROM memory chips are often used to store just a tiny quantity of data or programming instructions.