Micro SD cards are one of the smallest removable flash memory card formats designed specifically for small devices, primarily used as phone memory. Smaller than MiniCards, and also based on the SD card format, MicroCards measure approximately 15mm x 11mm, about the size of your little fingernail. Older devices only support Micro SD cards while newer devices support both Micro SD cards and Micro SDHC cards.
Micro can also be used on SD compatible devices via an SD adapter. Micro SD cards are becoming more and more popular because they are very small and thin, and mobile phones and minute MP4 video players are increasingly using this innovative space-saving technology.
speeds
The speed of a Micro SD card is measured by how quickly information can be read or written to the card. You can store higher definition of videos, higher resolution of photos and don’t have to worry about losing your precious data. In applications that require sustained write performance, such as video recording, the device may not perform satisfactorily if the card’s class rating falls below a particular speed.
In early cards, speed was measured by the “x” rating, which compared the average data read speed to that of the original CD-ROM drive. Currently, the official unit of measurement is the Speed Class Rating, which guarantees a minimum rate at which data can be written to the card.
New families of SD cards improve card speed by increasing the bus fare. Regardless of the speed of the bus, the card can signal to the host that it is “busy” until a read or write operation is complete. Compliance with a higher speed rating is a guarantee that the card limits its use of the “busy” indication.
Different speed classes
The Speed Class Rating is the official unit of measurement for speed. The class number guarantees a minimum write speed as a multiple of 8 Mbit/s (1 MB/s)
These are the ratings of all the cards currently available:
Class 2: 2 MB/s speed
Class 4: 4 MB/s speed
Class 6: 6 MB/s speed
Class 10 speed: 10 MB/s
Common Applications for Speed Classes
Class 2: H.264 video recording, MPEG-4, MPEG-2 video recording
Class 4: MEPG-2 (HDTV) Video Recording, Digital Still Camera (DSC) Consecutive Photo Shooting
Class 6: Megapixel DSC Consecutive Photo Shooting, Professional Video Camera
Class 10: Full HD video recording, consecutive HD still image capture