What's the difference between SD card and MMC card?

MMCA Association is an open normative association, which was founded by 14 Company in 1998. Its main function is to provide a multimedia card specification suitable for mobile phones, digital images and other electronic products for the industry. Multimedia card is a small memory card specification (24 mm x 32 or 18 mm x 1.4 mm) specially designed for mobile phones, digital images and other electronic products. These small memory cards are highly reliable, easy to carry and have standardized specifications. The storage capacity of the card can reach 1 gigabyte (640,000 pages of books can be stored). Multimedia cards can use ROM technology (which can only read data) or Flash technology (which can repeatedly read and write data).

Advantages: MultiMediaCard specification is supported by major mobile phone and semiconductor factories that produce flash memory in the world. Because the multimedia card fully conforms to the principle of point-to-point cross-platform use, the card has considerable development potential, and the power saving function of the multimedia card is very suitable for the application of handheld electronic products. At present, more than 2027 kinds of electronic products on the market support MultiMediaCard, and version 4.0 of MultiMediaCard has dual-stream function, which is the fastest card among all memory cards.

Disadvantages: MMCA is a completely open organization, which means that there is no dominant manufacturer to lead, and MMCA's efforts to promote MMC concept in the consumer market in the past were quite weak. Because of this, competing cards often criticize the slow transmission speed of general multimedia cards, but in fact, the transmission speed of high-quality multimedia cards is even faster than that of some SD brands. In 2004, the MMCA Committee was re-elected, and the new members are actively promoting the concept of multimedia cards in the consumer market. With the strong support of mobile phone manufacturers, it is estimated that MultiMedaCard will occupy the largest share of the memory card market in the future.

SD specification was formulated by Panasonic, Sandisk and Toshiba. After the establishment of SD Association, it was mainly to promote SD specification. SD is designed to be compatible with MulitMediaCard, with a volume of 24mmx 32mm x 2. 1mm and a weight of about 2g. Advantages: SD card is equipped with CPRM encryption function, and encryption technology should be implanted into the card when producing each card. The production of SD card needs to pay royalties to 3C, while the encryption part needs to pay royalties to 4C. There is a write protection switch on the left side of SD card.

The specification of SD card is mainly promoted by Panasonic (Panasonic) behind the scenes. The main reason is that Panasonic has powerful electronic products and is familiar with the dynamics of consumer electronic products. Panasonic can be said to be quite successful. The SD card mainly transmits information by 4 bits per second, which is fast. The main digital cameras and digital cameras use SD cards. At present, Japanese mobile phone manufacturers have launched mobile phones using SD cards, and like MultiMediaCard, there are more than 2027 kinds of electronic products using SD cards worldwide, which means that this card is suitable for peer-to-peer cross-platform use.

Disadvantages: Although SD card adopts CPRM encryption technology, there are not many electronic products that actually use this technology, which also increases the cost of SD card, because the use of CPRM requires the payment of patent fees, and the production of SD card itself also requires the payment of patent fees. Under the double royalty system, the cost of SD card is higher than other cards that do not need to pay royalties. (At present, the transmission speed of SD card is 4bit, which will reach 25 MHz in the future, and MMC will reach 8 bit in the future. It will reach 52 MHz in the future ... Therefore, SD may lag behind multimedia cards in the development of transmission speed in the future.

Multimedia card is a small memory card specification (24 mm x 32 or 18 mm x 1.4 mm) specially designed for mobile phones, digital images and other electronic products. These small memory cards are highly reliable, easy to carry and have standardized specifications. The storage capacity of the card can reach 1 gigabyte (640,000 pages of books can be stored). Multimedia cards can use ROM technology (which can only read data) or Flash technology (which can repeatedly read and write data). Recently, MMC released the specification of version 4.0, which makes the new card type work with the traffic of x 1, x4 or x8, and makes the maximum transmission speed of the card reach 52 megabytes per second, making it the fastest transmission speed among all memory cards. The speed, bad block management and compatibility of the card are managed by the control IC in the card.

At present, most SD electronic products on the market also support multimedia cards, but if the products only support multimedia cards, they do not support SD cards. The low power consumption of multimedia card is very suitable for handheld electronic products. SD is designed to be compatible with MulitMediaCard, with a volume of 24mmx 32mm x 2. 1mm and a weight of about 2g. SD card is equipped with CPRM encryption function, and encryption technology should be implanted into the card when producing each card. The production of SD card needs to pay royalties to 3C, while the encryption part needs to pay royalties to 4C.

There is a write protection switch on the left side of SD card.

The SD card mainly transmits information by 4 bits per second, which is fast. The main digital cameras and digital cameras use SD cards. At present, Japanese mobile phone manufacturers have launched mobile phones using SD cards, and like multimedia cards, there are more than 2027 kinds of electronic products using SD cards worldwide, which means that this card is suitable for point-to-point cross-platform use.

Although SD card adopts CPRM encryption technology, in fact, few electronic products use this technology, which also increases the cost of SD card, because the use of CPRM requires the payment of patent fees, and the production of SD card itself also requires the payment of patent fees. Under the double royalty system, the cost of SD card is higher than other cards that do not need to pay royalties. (At present, the transmission speed of SD card is 4bit, which will reach 25 MHz in the future, and MMC will reach 8 bit in the future. It will reach 52 MHz in the future ... so SD may lag behind multimedia cards in the development of transmission speed in the future.

At present, the transmission speed of SD card is suitable for digital cameras, digital cameras and other digital imaging products. At present, the SD card has been well-known in the market through the promotion of Panasonic, but it is worth noting that the high transmission speed of SD card also means high power consumption. It is recommended to use SD card for high-definition digital cameras or high-function cameras.

MMC has 7 pins and SD has 9 pins. Generally speaking, MMC can be used where SD can be used, but not where MMC can be used. But now most card stands are compatible with two cards, so in many cases, both cards can be used on the same product.

This answer comes from Baidu.