MicroSD

Overview
MicroSD is a flash memory card in the Secure Digital format. These cards are common in most modern mobile devices due to their small size.

The cards are the smallest commercial card, measuring 15mm x 11mm x 1mm, and are approximately one quarter the size of a normal SD card. In fact, a variety of adapters exist that are the size of an SD card, facilitating the use of microSD card in a normal SD card slot.

TransFlash and microSD formats are compatible. However, microSD contains SDIO mode, enabling the use of non-memory devices such as Bluetooth and GPS devices. Likewise, microSD and microSDHC share a similar form, but SDHC require different processing, making them incompatible with some devices.

MicroSD cards are typically available in 64MB to 2GB. MicroSDHC are available in 4GB to 64GB. MicroSDXC allows cards with even higher capacities.

Technical Details
MicroSD contains an 8-pin format, in comparison to the 9-pin format of SD cards. Power consumption varies between manufacturers, but typically lies in the range of 20-100mA at 3.3V.

The pin function varies based on the mode the microSD card in running in.