Comparison of SD card series

SD card

Secure digital card is abbreviated to SD card. Literally, this card is a security card. It is better in security performance than CF card and early SM card. It is a brand-new memory card product jointly developed by Panasonic, Toshiba and SanDisk in Japan. Its biggest feature is to ensure the security and confidentiality of data through encryption. SD card can be regarded as the upgrade of MMC in many aspects. The appearance and working mode of both are the same, except that the thickness of MMC card is slightly thinner, but any machine using SD card equipment can use MMC card. Its overall dimension is 32mm × 24mm × 2.1mm。

miniSD

The SD card is slightly bloated for small digital products such as mobile phones. At the same time, in order to catch up with duo and XD, the SD card camp has published a smaller memory card than the original, called "miniSD". Its overall dimension is 20mm × 21.5mm × 1.4mm, the package area is 44% of the original SD card, the volume is 63% of the original SD card, and it has 11 golden fingers (only 9 SD cards). It can also be used as an SD card through a transfer card. This card is widely used in Dopod, Panasonic and other mobile phones.

microSD

The microSD card standard was formulated by the SD Association in 2005 with reference to the relevant standards of T-Flash. T-Flash card and microSD card are compatible with each other. Compared with miniSD card, microSD card is smaller in size and 11mm in size × 15mm × 1.4mm, which is only about a quarter of the standard SD card, is the smallest memory card in the market at present.

T-Flash card

Full name: transflash, jointly developed by Motorola and SanDisk, was launched in 2004. It is a super small card (11 * 15 * 1mm), about 1 / 4 of the SD card, which can be considered as the smallest memory card at present. TF card can be used as SD card after passing through SD card converter. The adapter can be used on a device using SD as a storage medium. Transflash is mainly developed for camera phones to capture large-scale images and download large video clips. Transflash card can be used to store personal data, such as digital photos, MP3, games, applications and personal data for mobile phones, etc. it also has a copyright protection management system to protect downloaded music, images and games; The new transflash to be launched in the future also has encryption function to protect personal data, financial records and health and medical documents. The compact transflash allows manufacturers to adopt this design without worrying about the size of the phone. Another flexible application is that suppliers can replace it at any time according to the different needs of customers before delivery. This advantage is not available in embedded flash memory.

detailed description:

◆ the volume is about half of a SIM card, and the copyright protection management system is built in, which is suitable for many multimedia applications.

◆ after matching with the adapter, it can be used on digital products with SD card slot.

◆ size: 11mm * 15mm * 1mm.

SDHC is the abbreviation of "secure digital high capacity", that is, "High Capacity SD memory card". In May 2006, the SD Association released the latest version of the system specification of sd2.0, which stipulates that SDHC is an SD card that conforms to the new specification and has a capacity greater than 2GB but less than or equal to 32GB.

The biggest feature of SDHC is its high capacity (2gb-32gb). In addition, the SD Association stipulates that SDHC must adopt FAT32 file system, because the maximum capacity supported by FAT16 file system previously used in SD card is 2GB, which cannot meet the requirements of SDHC.

As the successor of SD card, the main feature of SDHC is that the file format has been upgraded from FAT12 and FAT16 to FAT32, and the maximum support is 32GB. At the same time, the transmission speed is redefined to class 2 (2Mb / sec), class 4 (4MB / sec), class 6 (6MB / sec), etc. the high-speed SD card can support real-time storage of high-resolution video recording.

Overall dimensions of SDHC card 32 × twenty-four × 2.1mm (long × wide × Like SD cards, copyright protection functions are the same as before. However, due to the change of the file system, SD devices that previously only supported FAT12 / 16 format are incompatible. Machines that also supported FAT32 (SDHC) can read existing FAT12 / 16 format SD cards.

All SD cards with a capacity greater than 2G must comply with the SDHC specification, which indicates that SDHC must at least comply with the speed class of class 2, and there must be SDHC marks and speed class marks on the cards.

In the market, some brands provide 4GB or higher capacity SD cards that do not meet the above conditions, such as the lack of SDHC marks or speed grade marks. These memory cards can not be called SDHC cards. Strictly speaking, they are not recognized by the SD Association. Such cards are likely to have compatibility problems with devices in use.

SDXC

SD Association showed a 2TB capacity SDXC memory card (SD extended capacity) at CES 2009.

SDXC not only has super large capacity, but also its data transmission speed is not bad. It is reported that its maximum transmission speed is expected to reach 300MB / s. If you have a super large capacity memory card, you can throw anything into it by using NDS burning card, memory stick vest or other friends in the future. However, the data security performance is not clear for the time being. This SDXC memory card uses NAND flash memory chip and uses Microsoft's exFAT file system (Vista's new file system).

(1) The current maximum capacity of SDXC memory card can reach 64GB. The theoretical capacity is 2TB.

(2) It supports UHS 104, a new ultra high speed SD interface specification. The new SD memory card standard ver.3.00 is the highest standard. It can achieve a bus transmission speed of 104mb per second on the SD interface, so as to achieve a maximum write speed of 35MB per second and a maximum read speed of 60MB per second.

(3) Uhs104 provides a traditional SD interface -- 3.3vds (25MHz) / HS (50MHz). The new SDHC memory card supporting uhs104 is compatible with the existing SDHC corresponding devices.

(4) The SDXC memory card is only compatible with the corresponding SDXC device equipped with exFAT file system. It cannot be used for SD or SDHC corresponding equipment.

(5) Adopt the most reliable CPRM copyright protection technology.

(6) Uhs104: it is a new ultra high speed interface specification, with a data bus transmission rate of 104mb per second. This is the highest standard in the new SD memory card standard ver.3.00.

(7) SDXC memory card: it is the next generation SD memory card standard defined by the SD Association in April 2009. In order to meet the growing demand for large capacity storage media and provide faster data transmission rate for rich storage applications. Compared with the SDHC memory card standard, which provides 4GB to 32GB capacity, the new SDXC memory card standard can achieve a capacity of more than 32GB, up to 2TB (TB: terabyte, terabyte, 1TB = 1024gb).