EMMC memories are found in a large number of devices and it is one of the most widely used types of flash memory on the market, but it is classified as a flash memory of a worse category than NVMe chips. What is it that differentiates eMMC memory from those of the same type, what is its architecture and how it works? Keep reading to know more.
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 complicates the creation of extremely compact designs that are common in mobile phones, tablets, portable consoles and ultrabooks.
What is NAND Flash memory?
We understand as memory what we also call non-volatile RAM, this is therefore memory that is not stored on a disk but on a semiconductor device in the style of a processor or RAM. To better explain it, a flash memory is a RAM memory that does not lose its data when the system is turned off, hence it is also called NVRAM or non-volatile RAM.
With NAND we refer to a type of logic gate, the Negated AND gate, which only lets through the electrical impulses or the signal when all the pins are with the signal low or all are 0. So a NAND Flash memory is composed by a large number of this type of doors placed in matrix.
NAND Flash is not the only type of logic gate used for storing data in non-volatile RAM or flash memory, but it is the most widely used due to the fact that it is the cheapest of all to manufacture. The consequences of this are that it is used both for all kinds of memory cards, eMMC and NVMe chips.
What do we understand by 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 number of pins 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 embedded or embedded MMC memory. If these words sound like Chinese to you, we mean that an eMMC memory is an MMC that has been soldered onto a board and is not part of a memory card. So the non-volatile memory included in an eMMC is in a BGA package that is intended to be soldered to a board.
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 to them, the nature of eMMCs is different, since they are not removable so they also incorporate the card’s reading and writing hardware in the same BGA package.
EMMC memory communication interface
With eMMC we also refer to a communication standard that indicates how different devices have to communicate with these non-volatile memory chips. Each of the eMMC chips have 11 control pins that are used to send data, 3 of them are for sending control and the other 8 pins are responsible for sending or receiving data at the rate of one bit per 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 or 8 | 0-26 MHz | 26 MB / s |
| High speed SDR | 1.2 V / 1.8 V / 3 V | 1, 4 or 8 | 0-52 MHz | 52 MB / s |
| High speed DDR | 1.2 V / 1.8 V / 3 V | 4 or 8 | 0-52 MHz | 104 MB / s |
| HS200 | 1.2 V / 1.8 V | 4 or 8 | 0-200 MHz | 200 MB / s |
| HS400 | 1.2 V / 1.8 V | 8 | 0-200 Mhz | 400 MB / s |
As you can see, its clock speed is not the same as that of an NVMe chip, that is why eMMC non-volatile memories are usually incorporated in devices such as mobile phones in which such a large bandwidth is not necessary or not. It is possible due to the high consumption of this when transmitting data. At the same time it can be seen how the faster eMMC memory has nothing to envy to the faster SATA disks, this allows low consumption devices such as tables and smartphones to have the performance of a SATA disk in terms of storage.
EMMC memory has an expiration date
The reason for this is the existence of the UFS standard, which has a much higher reading and writing speed than the most advanced eMMC standard, especially in random writing where it is up to ten times faster. This has caused systems to discard eMMC memory in favor of UFS except in cases where the speed of the interface with the NAND Flash of the eMMC interface does not result in a bottleneck.