The classic Secure Digital Card(SD) is a memory card with a storage capacity of up to 2 gigabytes( GB). Since this memory size is not sufficient for various applications, an SD card variant has been developed in the form of the Secure Digital Card High Capacity (SDHC) with much higher memory capacities of between 4 GB and 32 GB.
The SDHC card is available in five classes: 2, 4, 6, 8 and 10, which corresponds to the write speed in MB/s. The SDHC card is available in five classes: 2, 4, 6, 8 and 10. Class 2 then has a data rate of at least 2 MB/s, Class 4 one of at least 4 MB/s, Class 6 of 6 MB/s, and Class 10 of 10 MB/s. A speed increase to 10 MB/s and 30 MB/s is achieved by the UHS bus, Ultra High Speed (UHS), with which the SDHC cards are equipped.
The SDHC card is especially suitable for high- performance audio devices, video devices and telecommunication devices. According to the conception, there are three SD specifications for SD audio, SD video and SD binding. SD-Audio supports the transfer of music files, SD-Video is a service for downloading video files, and S-Binding allows downloaded files to be bound to the device. The SDHC card cannot be used in devices with SD card, but only in specially marked devices. In terms of size, the SDHC card is the same as the SD card. The same applies to the microSDHC card, which is the same size as the microSD card.