A generic 8 GB class 6 (6MB/s) MicroSD HC card. Shown on a US dime coin for reference.

An SD card, miniSD card, and microSD card.

2 GB MicroSD

microSD is a format for removable flash memory cards. SD is an acronym for Secure Digital. The cards are commonly used in cellular phones, as well as in 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 available commercially; at 15 mm × 11 mm × 1 mm (about the size of a fingernail), it is about a quarter the size of an SD card.^[1] There are adapters which allow a microSD card to be used in devices intended for SD, miniSD, Memory Stick Duo and even USB cards. However, they are not universally compatible. Many microSD cards sold online and in stores are packaged with an SD adapter to use the card in devices that take SD cards. TransFlash and microSD cards are the same (each can be used in devices made for the other), except that microSD adds support for SDIO mode, enabling non-memory cards like Bluetooth, GPS, and Near Field Communication devices.^[2]

A point of confusion can come from the difference in the microSD and the newer microSDHC format. The SD and SDHC share a similar form factor, but not all devices are compatible with the newer high capacity format. This is even true with devices that have been developed by SanDisk such as their e200 series of MP3 players. Using 3rd party firmware however, SDHC reading capabilities can be possible.^[3]

As of November 2009^[update], microSD cards are available in capacities from 64 MB to 32 GB. A 12 GB version was developed by SanDisk but never released.^[4] Cards with sizes over 2GB are almost all SDHC cards, though some early 4Gb SD Cards are not SDHC.

[edit] History

The microSD format was originally created by SanDisk. It was originally called T-Flash, and then TransFlash, before being renamed microSD when adopted by the SD Card Association (SDA). Other flash card formats approved by the SDA include miniSD and SD card.

The SDA announced the microSD format at CTIA Wireless 2005 on March 14, 2005, and approval of the final microSD specification was announced on July 13, 2005. At launch, the microSD format was available in capacities of 32, 64, and 128 MB. SanDisk introduced a 2 GB microSD card in July of 2006, initially priced at 99 USD. Since then, prices for flash memory devices have fallen dramatically. The same 2 GB card as of April 2009 can be found for as little as 12 USD at department stores, and as of May 2009 for as little as 6 USD at online electronics stores.

Today 16GB versions are on the market for under 50 USD.

[edit] Comparisons

Table data compiled mostly from simplified versions of MMC and SDIO specifications and other data on SD card and MMC association web sites. Data for other card variations is interpolated.

Capacity limit in all SD/MMC formats appears to be 128 GB in LBA mode (28-bit sector address).

[edit] Power Consumption

The power consumption of microSD cards varies by manufacture, but appears to be in the range of 20-100mA at a supply voltage of 3.3V. Specifications from TwinMos technologies (http://www.twinmos.com.tw) list a maximum of 45mA during transfer. Toshiba, on the other hand, lists 80-100mA: http://www.toshiba-memory.com/en/micro_sd_cards.html.

[edit] See also

• slotMusic

[edit] References

[edit] External links

• MicroSD details, compatibility, comparisons, and general information
• JESD84-C01 -- MultiMediaCard (MMC) Card Mechanical Standard

v • d • e Memory cards Main articles Memory card reader · Comparison of memory cards • SD Card and MultiMediaCard family comparison Types CompactFlash (CF) • JEIDA • Memory Stick (MS/MS-PRO) • miCard • Microdrive (MD) • PC Card • SmartMedia (SM) • SxS • Universal Flash Storage (UFS) • USB • xD-Picture MMC/SD Variants MultiMediaCard (MMC) • Secure Digital (SD) • miniSD • microSD