EMMC memory chips are commonly used in low power devices that do not require the speed of NVMe, but where the use of drives with moving parts makes it difficult to create extremely compact designs that are common in mobile phones, tablets, handheld consoles and ultrabooks. .
What is NAND Flash memory?
By memory is meant what is also called non-volatile RAM, it is therefore memory that is not stored on a disk but on a semiconductor device in the manner of a processor or a RAM. . To better explain it, flash memory is RAM memory that does not lose its data when the system is off, so it is also referred to as NVRAM or nonvolatile RAM.
With NAND, we refer to a type of logic gate, the negative AND gate, which only passes electrical pulses or signal through when all pins are signal low or all are 0. Therefore, a NAND Flash memory is composed of a large number of this type of doors placed in a matrix.
NAND Flash is not the only type of logic gate used to store data in non-volatile RAM or flash memory, but it is the most widely used because it is the cheapest of all to manufacture. The consequences are that it is used for all kinds of memory cards, eMMC and NVMe chips at the same time.
What is eMMC memory?
A few years ago, there was a type of non-volatile memory card called MultiMedia Card or also known as MMC. MMCs were created by the Joint Electron Device Engineering Council (JEDEC) and have become a standard for low cost flash memory due to their low pin count and portability. The vast majority of flash memory cards on the market are variants of the MMC standard.
Well, eMMC memory is nothing more than built-in or built-in MMC memory. If these words sound Chinese to you, we mean that an eMMC memory is an MMC that has been soldered onto a card and is not part of a memory card. Thus, the non-volatile memory included in an eMMC is in a BGA package which is intended to be soldered to a card.
Because flash memory cards need the reading and writing system to be outside of them, since it is necessary in this way to read and write on them, the nature of eMMCs is different, since they are not removable, so they also integrate reading and card reading. writing material in the same BGA package.
EMMC memory communication interface
With eMMC, we are also referring to a communication standard that indicates how different devices should communicate with these non-volatile memory chips. Each of the eMMC chips has 11 control pins which are used for sending data, 3 of them are for sending control and the other 8 pins are responsible for sending or receiving data at bit rate by pin.
When transferring data, eMMC chips support the following operating modes:
| Transfer mode | Voltage | interface (bits) | MHz | Bandwidth |
| MMC card | 1.2 V / 1.8 V / 3 V | 1, 4 of 8 | 0 to 26 MHz | 26MB / s |
| High speed SDR | 1.2 V / 1.8 V / 3 V | 1, 4 of 8 | 0 to 52 MHz | 52MB / s |
| High speed DDR | 1.2 V / 1.8 V / 3 V | 4 of 8 | 0 to 52 MHz | 104MB / s |
| HS200 | 1.2 V / 1.8 V | 4 of 8 | 0 to 200 MHz | 200MB / s |
| HS400 | 1.2 V / 1.8 V | 8 | 0 to 200 Mhz | 400MB / s |
As you can see, its clock speed is not the same as that of an NVMe chip, which is why eMMC nonvolatile memories are usually incorporated in devices such as mobile phones in which high bandwidth as important is not necessary or not. possible due to its high consumption during data transmission. At the same time, one can see how the faster eMMC memory compares with faster SATA drives, it allows low power devices such as tables and smartphones to have the performance of a SATA drive in storage.
EMMC memory has an expiration date
The reason for this is the existence of the UFS standard, which has a much higher read and write speed than the most advanced eMMC standard, especially in random write where it is up to ten times faster. . This has led systems to abandon eMMC memory in favor of UFS, except in cases where the speed of the interface with the NAND flash memory of the eMMC interface does not cause a bottleneck.
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