Difference between MMC and SD Interface

We frequently notice an SD/MMC slot when we look at card readers. As a result, it makes one wonder what is the difference between MMC and SD interface? Many common characteristics and physical and electrical standards between MMC and SD cards are the same. The commands at the software level are the primary area where the two standards vary. Numerous hosts can support MMC and SD cards using the same socket due to their similarity.

Actually, the MMC standard gave rise to SD. Although they no longer have identical sets of commands, the two are still electrically compatible. SD kept certain commands while adding others and removing others.

All SD hosts begin by utilizing the MMC command sets, despite the fact that they do not all use the same command sets. They then discuss which signaling commands will result in the fastest pace.

However, despite the fact that the SD and MMC interfaces are compatible, an SD card cannot fit in an MMC card slot. This is due to the physical variations among MMC and SD cards rather than the electrical connectivity. SD cards are about 2.1mm thick, while MMC cards are roughly 1.4mm thick. This makes it simple to insert an MMC card into more of an SD slot but difficult to do the opposite. Although they are rather uncommon, there is a variant of SD that is the same width as an MMC.

Even if you can fit one card into a different host despite the size limitations, it is still not advised to do so. This occurs as a result of the two standards' evolving differences over time. Because the MMC host is unable to handle the higher commands in SD, using an SD card in an MMC slot will prevent you from getting the fastest possible transfer speed.

Read this article to find out more about MMC and SD Interface and how they are different from each other.

What is MMC?

MMC cards are a kind of flash memory that saves data as electrical signals. The MMC opened the door for a variety of contemporary gadgets, including SD cards, smartphone CPUs, flash drives, and SSDs.

The typical MMC measures 24 mm x 32 mm x 1.4 mm. Despite their small size, MMC cards have a large storage capacity thanks to the way data is stored. You may now find MMC cards that can store up to 512 GB. MMC cards are substantially more sturdy than SD cards because they don't expose data to the surface. For internal storage, the majority of smartphones employ embedded MMC (eMMC).

Data is stored using NOR-based flash technology, which SanDisk invented. In contrast to the magnetic methods utilized by standard optical discs, it implies that the card can contain data in the manner of electrical signals.

A MMC card is still vulnerable to data loss despite reducing the interface area for a number of reasons. Vibrations or extreme physical force, unintentional file deletion, virus or malware or Using the card at an excessive voltage and removing it while transferring data

What is SD?

An improved version of MMC was employed to create SD cards. SD cards varies between 152 MB and 2 GB. Data on high-capacity SD cards ranges from 4GB to 32GB.These SD cards have a high storage capacity, or SDHC. Up to 2TB of data can fit on it. The SD card doesn't come with a file system by default. It operates on chunks of RAW data. The OS is in charge of creating a file system over the top of RAW space. The card is non-volatile. There are three different sizes available. SD, miniSD, and microSD.

Compared to conventional storage media, SD cards are more resilient. They have an operating shock rating of 2,000 Gs, which is equivalent to the height from which you can drop them and they would still function, as opposed to the mechanical drive of the standard portable computer device, which has a rating of 100 G to 200 G.

In February 2014, SanDisk released the first 128 GB microSDXC card. In September 2014, it released a 128 GB SDXC card. In March 2015, it released a 200 GB microSDXC card. In May 2016, Samsung released the first 256 GB microSDXC card in history.

When it comes to portable storage media, SD is currently regarded as the industry standard. It is utilized in almost every portable electronics with removable storage and rapidly outgrew MMC. MMC cards can be read by SD hosts. MMC card slots cannot accommodate SD cards. SD cards won't operate at their fastest in an MMC slot, and the opposite is true.

Difference between MMC and SD Interface

The following table highlights the major differences between MMC and SD Interface −


SD Interface

MMC Stands for Multi Media Card

SD Stands for Secure Digital Card

It is used as a portable devices like digital cameras, cellular phones, digital audio players, and PDAs

It is used as a storage media for the devices like Wii, Sony PS 3, Camcorders, Cellular phones, digital audio players, and PDAs

MMC can only store up to 32 MB of data

SD can only store up to 4TB of data

MMC cards have dimensions of 24.0mm × 32.0mm × 1.4mm

SD cards have dimensions of 32.0mm × 24.0mm × 2.1mm

MMC was produced by SanDisk and Siemens

SD was produced by SanDisk, Toshiba, and Panasonic.

MMC comes in the forms of MMC, RSMMC, MMC PLUS, and metal extension

SD is available in the forms of SD, miniSD,and microSD.

digital cameras use MMC.

Mobile phones utilize SD cards

The file system of MMC is FAT 16.

The file system of SD is FAT 16


All the above information given above could help you to understand the difference between the MMC and SD Interface. The both interface are the storage devices. The MMC contains a higher transfer rate when we compare to the SD, and it is best option for transferring the larger files quickly. You can use any type of the storage device, but it is mandatory to take the backup of your data to avoid the data deletion and corruption.

Updated on: 19-Jan-2023

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