microSD is a kind of removable flash memory card used for storing information. SD is an abbreviation of Secure Digital. The cards are used in cellular phones. They are also used in newer types of handheld GPS devices, portable media players, digital audio players, expandable USB flash memory drives, Nintendo DS flashcards, and digital cameras.
It is the smallest memory card that can be bought; at 15 mm × 11 mm × 1 mm (about the size of a fingernail), it is about a quarter of the size of a normal-sized SD card. There are adapters that make the small microSD able to fit in things that have slots for standard SD, miniSD, Memory Stick Duo and even USB cards. But, not all of the different cards can work together. Many microSD cards sold on the internet and in stores have a standard SD adapter, so that people can use them in things that take standard SD but not microSD cards.
TransFlash and microSD cards are the same (they can be used in place of each other), but microSD has support for SDIO mode, so that non-memory cards like Bluetooth, GPS, and Near Field Communication devices to use the card also.
Some people have a hard time knowing the difference between the microSD and the newer microSDHC format. The SD and SDHC act the same, but not all devices are able to be used with the newer format. This is even true with devices that have been made by SanDisk like their e200 series of MP3 players. Using 3rd party firmware, SDHC reading can sometimes be done.
TransFlash cards are sold in 16MB and 32MB sizes. microSD cards are sold in many sizes, from 64 MB to 2 GB, while microSDHC cards are sold in sizes between 4 GB to 64 GB. (This is the biggest microSD card so far, and the microSDHC format can not store anything past that amount. microSD cards with even more storage will be in microSDXC format.)
The microSD format was made by the company SanDisk. It was first called T-Flash, and then TransFlash, before being named microSD when it started to be used by the SD Card Association (SDA). Other flash card formats approved by the SDA include miniSD and standard SD card.
The SDA announced the microSD format at CTIA Wireless 2005 on March 14, 2005, and the final microSD details were announced on July 13, 2005. Then they were first sold, the microSD format was sold in sizes of 32, 64, and 128 MB. SanDisk made a 2 GB microSD card on July 2006, at first costing $99 (USD). Since then, the prices for flash memory devices have gotten much lower. At the time of April 2009, the same 2 GB card could be bought for as low as $12 (USD) at department stores, and by May 2009, for as low as $6 (USD) at online electronics stores. In January 2010, a 16 GB micro SD card class 2 cost about $40 (USD), and a 4 GB class 2 micro SD card about $8 (USD).
Power Usage [change]
The amount of power used by microSD cards are all different because they are made by different manufacturers, but it looks like it is in the range of 20-100 mA at a supply voltage of 3.3 V. TwinMos technologies says that the cards carry a maximum of 45 mA during transfer. Toshiba lists 80-100 mA.