FRAM Iron and electronic memory

The difference between ferroelectric memory and conventional memory.

One: Volatile memory includes static memory SRAM and dynamic memory dram.
Advantages: Read and write fast, read and write life without restriction times.
Disadvantage: Loss of power will lose data.

Second: Non-volatile memory now includes EEPROM and Flash, but they are all developed in ROM technology.
Advantage: The power-down data will be saved.
Cons: Write time is slow (typically every write, requires a buffer or pre-flush of 5 to 10 milliseconds)
High-voltage write (12V to 24V High write voltage internally)
High power consumption
Read-Write frequency restriction (EEPROM is 1 million times, Flash is 100,000 times)

Three: The ferroelectric memory includes all the advantages of RAM and ROM. (It can be said that ferroelectric is a kind of power-down data saved RAM)
Advantages: Fast read/write speed (up to Dana Second level)
Minimum read and write times of 10 billion (high voltage operation is 10 billion times, low voltage is unlimited)
Low power consumption (no high-voltage write required)
Power-down data not lost (save 10 years)
You can replace the normal Eeprmo or RAM directly on the product.

Ferroelectric storage technology was put forward in 1921, until 1993, the United States Ramtron International Company successfully developed the first 4K-bit ferroelectric memory Fram products, all of the Fram products are manufactured or licensed by Ramtron company. In recent years, Fram New development, the use of the 0.35 m process, the introduction of 3V products, the development of "single-tube single-capacity" storage unit Fram, the maximum density of up to 256K
Now the most common program memory is flash, it is very convenient and cheaper to use. Program memory must be non-volatile and relatively inexpensive, and relatively easy to rewrite, while the use of Fram is limited by the number of accesses.

Compared to other types of semiconductor technology, ferroelectric memory has some unique characteristics. The traditional mainstream semiconductor memory can be divided into two categories--volatile and non-volatile. Volatile memory includes the static memory SRAM (the "Static Random Access Memory") and the Dynamic memory dram (Dynamics random access memory). SRAM and DRAM lose their saved data when power is lost. Ram-type memory is easy to use and performs well, but they also lose their saved data in the event of power loss.
Nonvolatile memory does not lose the stored data in the case of power-down. However, all major non-volatile memory sources are derived from read-only memory (ROM) technology. As you can guess, what is called read-only memory is certainly not easy to write, and in fact it cannot be written at all. All memory developed by ROM technology has the characteristics of difficult to write information. These techniques include EPROM (almost abolished), EEPROM, and Flash. These memories are not only slow to write, but can only be erased for a limited number of times, and power consumption is high when writing.

The ferroelectric memory is compatible with all functions of RAM and, like ROM technology, is a non-volatile memory. Ferroelectric memory A bridge between the two types of storage-a non-volatile ram-is built up across a ravine.

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The core technology of Ramtron Corporation ferroelectric Memory (FRAM) is ferroelectric crystal material. This special material enables the ferroelectric memory to have both random access memory (RAM) and non-volatile memory characteristics. Ferroelectric crystals work by: When an electric field is added to an ferroelectric crystal, the central atom in the crystal moves in the direction of the electric field to a stable state. Each free-floating central atom in the crystal has only 2 stable states, one is recorded as 0 in logic and the other is recorded as 1. Center atomic energy at room temperature, no electric field, stay in this state for more than 100 years. The ferroelectric memory does not need to be refreshed regularly and can save data in the event of a power outage. Because there is no atom collision throughout the physical process, the ferroelectric memory features high-speed reading and writing, ultra-low power consumption, and infinite write.
Compared with E2prom, ferroelectric memory mainly has the following advantages:
(1) Fram can write to the data at the bus speed, and after the write does not need any delay wait, and e2prom after writing generally to 5~10 ms waiting data write time;
(2) Fram has almost unlimited write life. The lifetime of the general E2prom is 100,000 to 1 million writes, while the new generation of ferroelectric memory has reached the Shing time of the write life.
(3) E2prom slow and high current write make it need to Fram 2 500 because of the advantages of Fram, it is particularly suitable for those occasions where data acquisition and write time are very high, without loss, and the reliable storage capability allows us to store some important data in it. Its almost unlimited write life, making him a very suitable for the important system of temporary memory, used to transfer a variety of data between subsystems, for each subsystem to read and write frequently.

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Comparison of Fram with other storage technologies

At present, Ramtron Company's Fram mainly consists of two major categories: serial Fram and parallel Fram. The serial Fram is also divided into two-wire mode of the FM24XX series and SPI three-way FM25XX series. Serial Fram is compatible with conventional 24xx and 25xx e2prom pins and timing, and can be replaced directly, such as Microchip, Xicor company's same model, parallel Fram price is higher but faster, due to the existence of "pre-charge" problem, in the timing of different, cannot be replaced directly with the traditional SRAM.

Fram products have the advantages of RAM and ROM, read and write fast, and can be used like nonvolatile memory. Due to the inherent shortcomings of ferroelectric crystals, the number of visits is limited, beyond the limit, Fram is no longer non-volatile. The maximum number of visits given by Ramtron is 10 billion (10 10), but it does not mean that after this number of times the Fram will be scrapped, but it is simply not nonvolatile, but it can still be used like normal RAM.

(1) Fram and E2prom

Fram can be a second option for E2prom. In addition to E2prom performance, it is much faster to access. However, before deciding to use Fram, you must determine that there is absolutely no danger in the system once the 10 billion accesses to the Fram are exceeded.

(2) Fram and SRAM

SRAM is superior to Fram in terms of speed, price and ease of use, but Fram has some advantages over the whole design.

Suppose the design requires about 3KB of SRAM, and hundreds of bytes to hold the E2prom configuration of the boot code.

Non-volatile Fram can save startup programs and configuration information. If the maximum access speed of all the memory in the application is 70ns, then the system can be completed with 1 Fram, making the system structure simpler.

(3) Fram and DRAM

DRAM is suitable for occasions where density and price are more important than speed. For example, DRAM is the best choice for graphics display memory, with a large number of pixels to store, and recovery time is not very important. If you do not need to save the last time at the next boot, use the volatile DRAM memory. The function and cost of DRAM is Fram. It turns out that DRAM is not a substitute for Fram.

(4) Fram and Flash

Now the most commonly used program memory is flash, it is very convenient and cheaper to use, program memory must be non-volatile, and relatively inexpensive, but also relatively easy to rewrite. The use of Fram is limited by the number of accesses.

FRAM Iron and electronic memory