Differences between SLC, MLC and TLC for SSD Leave a comment

The main ICs that make up SSD are master chips and NAND flash memory. Many people think that the performance of SSD can be known by simply looking at the master. In fact, this is a mistake. Just like some manufacturers’product lines, SandForce SF-2281 master is used. However, there are many different levels of products with different flash memory and firmware, and their performance is quite different from each other. It can be seen that both the firmware used by SSD and the type of flash memory have a considerable impact on its performance.

Differences between NAND flash SLC, MLC and TLC:

TLC is a type of flash memory called Triple-Level Cell

TLC chip technology is an extension of MLC and TLC technology. The earliest architecture of NAND Flash technology was SLC (Single-Level Cell). The principle is to store 1 bit of data in one storage unit (cell). Until MLC (Multi-Level Cell) technology is connected, the architecture evolves into a storage unit to store 2 bits.

The TLC architecture was officially launched in 2009, representing a memory storage unit that can store 3 bits, further reducing costs significantly. As with the previous wave of SLC technology to MLC technology trends, this was also triggered by the NAND Flash Toshiba plant, after which Samsung Electronics rushed to join the battle, making the entire TLC technology mass produced and used in terminal products.

Although TLC chips have larger storage capacity and lower cost, they can only be used on low-level NAND Flash-related products, such as low-speed flash memory cards, small memory card microSDs, or carry-on disks, due to reduced performance. However, embedded storage applications, smartphones, solid-state hard disks (SSDs) and other high-speed applications, such as NAND Flash performance and error-free, must use SLC or MLC chips.

In 2010, the main driver of NAND Flash market growth was smartphones and tablets, which had to use SLC or MLC chips. As a result, both chips were out of stock, while TLC chips continued to be in excess of supply and pulled down the average price of the entire industry, causing iSuppli, a municipal regulator, to see a rare market shrinkage when it counted global NAND Flash output in the second quarter of 2010. From $43 billion in the first quarter of 2010 to $4.1 billion, a decrease of 65%.

SLC of ssd

Differences among SLC, MLC and TLC flash memory chips used in Udisk MP3:

SLC = Single-Level Cell, or 1bit/cell, which is fast, lifetime, expensive (about 3 times more expensive than MLC), and has a lifetime of about 100,000 erases

MLC = Multi-Level Cell, or 2bit/cell, with average speed, average price, and approximately 3000-10000 erases

TLC = Trinary-Level Cell, or 3bit/cell. There is also Flash manufacturer called 8LC. It has a slow life, short life, low price, and about 500 erase lifetimes. At present, no manufacturer can do 1000 erases.

The lifetime of the flash memory to be explained refers to the number of writes (erases), not reads, since reads have little effect on the lifetime of the chip.

The following are the lifetime differences of three generations of SLC, MLC and TLC flash memory:

SLC uses a floating gate with positive and negative charges to store one bit of information and has an erase lifetime of about 100,000 times.

MLC uses charges at different potentials, and a floating grid stores 2 bits of information. It has about 10,000 erase lifetimes, doubles the capacity of SLC to MLC, and shortens the lifetime by 1/10.

TLC uses charges at different potentials, and a floating grid stores three bits of information, approximately 500-1000 erases, doubles the capacity of MLC to TLC, and shortens the lifetime by 1/20.

Flash memory products are getting shorter and shorter. There are already TLC flash memory products on the market. In view of the large difference between SLC and MLC or TLC flash lifetime, manufacturers of digital products are strongly required to label SLC and MLC or TLC flash products on their products using flash memory.

Many people don’t know the difference between SLC and MLC for flash memory. For the current hot MP3 walkman, do you want to buy SLC or MLC flash memory chips? Let me tell you first here that if you do not have a high capacity requirement, but have a high requirement on machine quality, data security, machine life, etc., SLC flash memory chip is the preferred choice. However, the cost of large-capacity SLC flash memory chips is much higher than that of MLC flash memory chips, so at present, for large-capacity of more than 2G, low-cost MP3 mostly uses MLC flash memory chips. High-capacity, low-cost LCD flash memory is naturally popular, but its inherent drawbacks have to be considered.

What is SLC?

The full name of SLC (Single Level Cell – SLC) is single-layer storage. Mainly used by Memoboss, Samsung, Hailishi, Meiguang, Toshiba, etc. SLC technology is characterized by thinner oxide film between the floating gate and the source. When writing data, the stored charge can be eliminated by adding a voltage to the floating gate and then passing through the source. In this way, an information unit can be stored. This technology can provide fast programming and reading, but it is limited by Siliconefficiency. More advanced process enhancements are required to upgrade the SLC process technology.

What is MLC?

The full name of MLC (Multi Level Cell – MLC) is multilayer storage. Mainly used by Toshiba, Renesas, Samsung.

Intel first developed MLC in September 1997. It stores two units of information in a Floating Gate (the part of the flash storage unit that stores the charge), then uses the charge of different potentials (Levels) to control precise reading and writing through the voltage stored in memory. By using a large number of voltage levels, MLC stores two bits of data per cell, which is denser. The SLC architecture has values of 0 and 1, while the MLC architecture can store more than four values at a time, so the MLC architecture can have a good storage density.

Advantages of MLC over SLC:

Signed in the current market mainly focuses on SLC and MLC storage, we know more about SLC and MLC storage. The SLC architecture has values of 0 and 1, while the MLC architecture can store more than four values at a time, so the MLC architecture has a high storage density and can utilize older production process equipment to increase product capacity without additional investment in production equipment, with the advantages of cost and yield. Compared with SLC, MLC has lower production cost and larger capacity. If improved, the read and write performance of MLC should be further improved.

Disadvantages of MLC over SLC:

There are many drawbacks to the MLC architecture. First, it has a shorter lifetime. The SLC architecture can write 100,000 times, while the MLC architecture can only withstand about 10,000 writes.

Secondly, the access speed is slow, under the current technical conditions, the theoretical speed of MLC chip can only reach about 6MB. The SLC architecture is more than three times faster than the MLC architecture.

Moreover, MLC consumes more energy than SLC and about 15% more current than SLC under the same operating conditions.

Although MLC has many disadvantages compared with SLC, it still has an absolute advantage in terms of single chip capacity. Due to the absolute advantages of MLC architecture and cost, it can meet the market demand of 2GB, 4GB, 8GB or even larger capacity

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