Difference Between SDHC and SDXC

SDHC vs SDXC

SDHC and SDXC are two variants of the SD (Secure Digital) memory card format. Secure Digital –SD is a nonvolatile memory card (Flash Memory) used in mobile devices because of their size. They are used in mobile phones, digital cameras, and palmtop/tablet computers. SD is a standard maintained by the Secure Digital Association, and the memory cards are manufactured under hundreds of brands.

SD cards are available in three classes, divided based on the capacity. Those areSDSC– Secure Digital Standard Capacity, SDHC – Secure Digital High Capacity, and SDXC Secure Digital eXtended Capacity. The initial SD cards had the capacity up to 2GB only. Therefore, SDHC and SDXC were introduced to increase the capacity available in SD cards. SD cards are manufactured in 3 different sizes in each category. Standard, mini and micro are those three types in production. They have the following dimensions.

标准：32.0×24.0×2.1 mm或32.0×24.0×1.4 mm

Mini: 21.5×20.0×1.4 mm

Micro: 15.0×11.0×1.0 mm

SD cards are further classified by the data transfer speed. The data transfer speed determines the specific applications of the SD cards. Therefore, the speed class is also important when considering the SD cards. There are 5 speed classes; they are as follows.

•SD视频录制的2 - 2类MB/sec（Mbps）

• Class 4 – 4 MB/sec (MBps) high-definition video (HD) to Full HD video recording

• Class 6 – 6 MB/sec (MBps)for HD video,

• Class 10 – 10 MB/sec (MBps) for Full HD video recording and consecutive recording of HD stills

• UHS Speed Class 1 – used for real-time broadcasts and large HD video files

SDHC

Defined in the version 2.0 of the SD specification, SDHC allows card capacities from 4 to 32 GB. SDHC is manufactured in all three sizes; standard, mini, and micro SDHC. SDHC cards are formatted with FAT32 file system.

The SDHC card readers can read SDSC (SD Standard Capacity) cards while SDHC cards cannot be read using SDSC readers.

SDXC

SDXC is the next version of the SD standard, which is designed to allow storage capacities from 32 GB to 2 TB (Terabytes). SDXC cards in current production have capacities up to 64 GB only. They are formatted with exFAT file format.

此外，尽管SDXC主机设备可以接受所有类型的SD卡，但较旧的主机设备无法使用SDXC卡。

What is the difference between SDHC and SDXC?

• SDHC and SDXC are two types of SD (Secure Digital) flash memory cards used in portable/mobile devices and computers. SDHC comes in standard, mini and micro packages while SDXC comes in standard and micro packages

• SDXC is the newer standard of the SD specifications.

• SDHC cards have storage capacities ranging from 4GB to 32 GB while SDXC cards have storage ranging from 32 GB – 2TB. Only cards up to 64 TB are currently in production.

• SDHC cards have FAT32 file format, whereas SDXC has exFAT file format.