Flash Memory By Arjun Sabat Roll No: EE 200113365 Under the guidance of Mr. Gayadhar Panda
INTRODUCTION • Flash Memory is solid state non-volatile memory. • It stores electrical charges rather than magnetic media. • Flash memory is light,compact,energy efficient and less expensive. • it is a ideal storage medium for digital camera,smart card etc.
WHAT IS FLASH MEMORY? • Flash memory is electronically erasable, electronically programmable, (generally) read-only memory. • From an embedded system designer’s perspective, the key difference between flash memory and EEPROM is that flash devices are block structured; that is, while flash memory locations are individually programmable, they are not individually erasable the way they are with EEPROM.
Flash memory is erased in sections whose sizes and locations in the chip are defined by the part’s manufacturer. • As a result, once a flash memory location is programmed, the entire section containing the location must be erased before that location can be programmed again.
HOW FLASH MEMORY WORKS • Flash memory is a type of EEPROM chip. • Flash memory cell consists of two transistors and these transistors are separated by a thin oxide layer. • One transistor is called floating and other one is control gate. • A cell censor monitor the level of charge passing through floating gate. if the flow through the gate is greater than 50%of charge its value is ‘1’. If charge passing drops below 50% threshold it’s value is ‘0’.
MLC TECHNOLOGY • MLC stands for Multi Level Cell • MLC Technology allows storage multiple bits per memory cell by charging memory cell to different voltage level. • These significantly increase the number of bits stored per area. • It may store per cell or thee bits per cell. • It significantly decrease the cost per Megabyte.
HOW TO ERASE & WRITE TO FLASH? • Flash memory is a type of EEPROM chip. It has a grid of columns and rows with a cell that has two transistors at each intersection. The two transistors are separated from each other by a thin oxide layer. • Programming algorithms specifiedto Flash controller is used to control Flash memory.
ADVANTAGES • Flash memory is noise less. • It allows faster access. • It is smaller size and lighter. • It has no moving parts.
LIMITATIONS • Flash memory costs five to ten times more than standard DRAM. • Another downside is the overabundance of formats. • Huge premium to pay power saving of flash memory.
FLASH APPLICATIONS Nonvolatile storage needed but battery not desirable. In an application where long-term data storage is required but a battery is not desirable, flash provides an ideal alternative to battery-backed static RAM.
CONCLUSION • Flash memory thus can provide an alternative to conventional DRAM memory. But it’s cost has to be decreased drastically to ensure that it replays the DRAM quickly. • By use of MLC technology the memory capacity of flash memory can be increased and thus the cost can be decreased.