SD and SDHC cards are used in electronic devices, such as digital cameras.
The SD memory card specification allows for the creation of easily portable memory cards that are compatible with more than 400 devices. Variations of SD cards are used to provide data storage in cellular phones, camcorders, MP3 players, digital cameras and a variety of video game systems. SDHC cards, a higher-capacity version of standard SD cards, expand the available storage space of compatible devices even further.
SD Cards
Standard SD cards meet the SD 1.0 specification and provide up to 2 GB of data storage for devices. SD cards are formatted by default using the FAT32 flash media format. The cards can be used to store music, digital pictures, video and game data for any device labeled for use with SD, SDHC or SDXC cards. Computer adapters or USB devices which accept SD cards allow the cards to be used with a PC to transfer files or to act as additional file storage space.
SDHC Cards
SDHC cards conform to the SD 2.0 specification and provide significantly larger amounts of data storage space. SDHC cards are available in storage capacity sizes ranging from 4 GB to 32 GB and are also formatted using FAT32. Not all SD-compatible devices are compatible with SDHC cards; the cards should only be used in devices that specify compatibility with SDHC or SDXC cards or which state compatibility with cards in the SD format at a capacity greater than 2 GB.
Available Sizes
Both SD and SDHC cards are available in three different size configurations. Standard size SD and SDHC cards are 32mm x 24mm in size with a thickness of 2.1mm. MiniSD and miniSDHC cards are 21.5mm x 20mm with a thickness of 1.4mm. MicroSD and microSDHC cards are 15mm x 11mm in size and 1mm thick. Mini and micro SD and SDHC cards are available at the same capacities as the standard cards of each format. Standard cards feature a 9-pin interface, micro cards feature an 11-pin interface and mini cards feature an 8-pin interface for connecting with devices. Write protection is available on standard-sized SD and SDHC cards, but not on mini or micro cards. Adapters are available which enable mini and micro cards to be used with standard-sized devices.
Speed Classes
SD and SDHC cards both make use of the standard Speed Class categorization for the SD card interface. The Speed Class of a card indicates the rate at which it transfers data; cards can have a Speed Class of 2, 4 or 6 for standard-speed transfers or 10 for high-speed transfers. SDHC cards can also be used in devices which support UHS Speed Class 1, a faster transfer class that standard SD cards are not compatible with.
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