Secure Digital
"SDHC" redirects here. For the gene, see SDHC (gene).
 SD (top), miniSD, microSD cards | |
| Media type | Memory card |
|---|---|
| Capacity | SDSC (SD): 1 MB to 2 GB, some 4 GB available. SDHC: 4 GB to 32 GB SDXC: ≥32 GB to 2 TB |
| Developed by | SD Card Association |
| Dimensions | Standard: 32×24×2.1 mm Mini: 21.5×20×1.4 mm Micro: 15×11×1.0 mm |
| Weight | Standard: ~2 g Mini: ~0.8 g Micro: ~0.25 g |
| Usage | Portable devices, including digital cameras and handheld computers |
| Extended from | MultiMediaCard (MMC) |
The Secure Digital format includes four card families available in three different form factors. The four families are the original, Standard-Capacity (SDSC), the High-Capacity (SDHC), the eXtended-Capacity (SDXC), and the SDIO, which combines input/output functions with data storage.[2][3][4] The three form factors are the original size, the "mini" size, and the "micro" size (see illustration). There are many combinations of form factors and device families.
Electrically passive adapters allow the use of a smaller card in a host device built to hold a larger card.
Host devices that comply with newer versions of the specification provide backward compatibility and accept older SD cards, but older host devices do not recognize newer cards. The SDA uses severaltrademarked logos to enforce compliance with its specifications and assure users of compatibility.[5]This article explains several factors that can prevent the use of a newer SD card:
- A newer card may offer greater capacity than the host device can handle.
- A newer card may use a file system the host device cannot navigate.
- Use of an SDIO card requires the host device be designed for the input/output functions the card provides.
- The organization of the card was changed starting with the SDHC family.
- Some vendors produced SDSC cards above 1 GB before the SDA had standardized a method of doing so.
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