Secure Digital High Capacity (SDHC) vs. Secure Digital Extended Capacity (SDXC)

Physically and electrically, SDHC cards mirror the standard-capacity SD cards (SDSC). However, the redefinition of the Card-Specific Data (CSD) register in Version 2.0 and the preformatting of SDHC cards with the FAT32 file system mark the key differences between SDHC and SDSC cards.

Version 2.0 also introduced a high-speed bus mode for both SDSC and SDHC cards. This enhancement doubles the original Standard Speed clock, enabling a data transfer rate of 25MB/s.

While SDHC host devices are designed to accept older SD cards, older host devices may not recognize SDHC (or, for that matter, SDXC) memory cards without a firmware upgrade. For older Windows operating systems predating Windows 7, patches or service packs are necessary for users to access SDHC cards.

A key feature of the SDXC format is its adoption of Microsoft’s exFAT file system. This allows for handling larger files and provides improved performance and reliability.

Version 3.01 also introduced the Ultra High Speed (UHS) bus, applicable to both SDHC and SDXC cards. This innovation boosted interface speeds from 50MB/s to 104MB/s for the four-bit UHS-I bus. Notably, this speed has been surpassed with advancements in technology, such as proprietary technology from SanDisk offering 170MB/s read speed and similar offerings from Lexar and Kingston.

The story does not stop there. Version 4.0, launched in June 2011, introduced the four-lane (two differential lanes) UHS-II bus, enabling speeds of 156MB/s to 312MB/s. This enhancement necessitated an additional row of physical pins.

Version 5.0, announced in February 2016, incorporated “Video Speed Class” ratings for UHS cards. This enabled the accommodation of higher-resolution video formats, such as 8K. These new ratings stipulate a minimum write speed of 90 MB/s, ensuring smooth video recording and playback.

SDHC cards are convenient for storage and excel in transferring files between devices. SDHC cards provide a versatile solution for several applications, including moving photos from a digital camera to a computer, sharing files between smartphones and tablets, and transferring music to gaming consoles.

Formatting an SDHC card is a straightforward process. Users must navigate to the formatting or storage section in their device settings or menu options, select the SDHC card, and choose the format option. It is important to note that formatting erases all data on the card, making it advisable to back up any important files beforehand. Moreover, formatting can improve the card’s performance by organizing data more efficiently, addressing potential issues of fragmentation or corruption that may impact read and write speeds.

As devices like smartphones and cameras often have limited built-in storage, SDHC cards offer a practical solution to expand storage capacity. With capacities generally available up to 32GB, these cards enable users to store more photos, videos, applications, and files. In fact, a 32GB SDHC card could store approximately 5,500 photos at a resolution of 12 megapixels, 21 hours of HD videos assuming an average file size of 1.5GB per hour, or 8,000 songs assuming an average song file size of 4MB. However, if a larger storage space is required, secure digital extended capacity (SDXC) cards are an alternative, offering capacities up to 2TB. However, not all SDHC-compliant cards are compliant with the SDXC standard. Readers must also acknowledge that file size can vary significantly, and the above numbers are only indicative.

SDHC cards vary in speed, as denoted by speed classes represented by numbers inside a circular symbol on the card. A higher number signifies a faster card, which is crucial for tasks such as recording high-quality video. Additionally, certain SDHC cards have security features like password protection and encryption to safeguard data from unauthorized access.

While some SDHC cards are designed to be relatively durable with features like shock resistance and waterproofing, it is essential to handle them with care. Users must avoid exposing their cards to extreme temperatures or moisture, and when not in use, store them in a protective case. It is worth noting that SDHC cards can typically be used in devices supporting SDXC cards, but their capacity will be limited to a maximum of 32GB. When larger capacities are supported, opting for an SDXC card is recommended.

Accidental overwriting or deleting data on an SDHC card is possible, especially if you are not careful while managing files. It’s advisable to double-check actions like formatting or deleting files and create backup copies of essential data to prevent any losses.

Finally, compatibility issues may arise when attempting to use an SDHC card in a device requiring a miniSD card, as they have different physical sizes and connectors. Nevertheless, some devices offer compatibility with both standard-sized SDHC cards and miniSD cards through adapters, providing a versatile solution for various devices and scenarios.

It’s important to note that SDXC cards are not backward compatible with hosts that only support SD (128MB to 2GB) or SDHC (4GB to 32GB) cards. To ensure compatibility, users must look for the SDXC logo on both cards and hosts when purchasing devices such as cameras, camcorders, drones, and readers. A good rule of thumb is to check the cutoff year: card readers on laptops manufactured before 2008 are less likely to support SDXC cards. However, SDXC cards will function in SDHC-compatible readers (not SD readers) if the computer supports the exFAT file system.

SDXC cards are ideal for storing many files and are suitable for ultra-high-resolution video footage, such as 4K and 8K. Thanks to their ample storage space, SDXC cards are perfect for professional cameras, like SLR cameras and action cameras. They are also an excellent choice for creating corporate videos.

There’s little difference between SDHC and SDXC cards in terms of speed. Both types can achieve fast read and write speeds. However, more high-end SDXC cards are available, while most SDHC cards fall into the basic or mid-range category. For users seeking a memory card with fast maximum speeds, a broader selection is available among SDXC cards.

A 2TB SDXC card could store approximately 200,000 photos at a resolution of 12 megapixels, 1,333 hours of HD videos assuming an average file size of 1.5GB per hour, or 400,000 songs assuming an average song file size of 5MB. Readers must acknowledge that file size can vary significantly, and the above numbers are only indicative.

Finally, SDXC cards are generally unsuitable for devices with only a microSD slot.

In the smartphone space, an SDHC card can be used to store apps and games. However, this feasibility depends on the operating system and settings of the specific device. While some Android phones allow apps to be moved to the SDHC card, iPhones generally do not support this feature.

For those interested in videography, an SDHC card can be used to record HD video. However, ensuring that the card’s speed class is compatible with the camera or camcorder being used for optimum user experience is crucial. A higher-speed SDHC card, such as Class 10 or above, is recommended for smooth HD video recording.

Some devices with compatible operating systems can run software applications directly from an SDHC card. This can be particularly useful for running lightweight programs on devices with limited built-in storage. However, this is not a common practice because running software directly from an SDHC card often leads to potential performance limitations.

Lastly, many gaming consoles support using SDHC cards to expand storage. This can be used for game saves, downloadable content, and even game installations, making it a valuable asset for gamers, especially those with consoles with limited internal storage.

It is important to note that modern-day devices prefer SDXC over SDHC for its increased storage volumes and transfer speeds, perhaps putting this standard on the path to obsolescence over the long term. But for now, SDHC cards are still widely used in many existing devices and offer a good balance of affordability and storage for everyday tasks.

Digital cameras

SDXC cards are frequently used in digital cameras, particularly DSLRs and mirrorless cameras. High-resolution photos and videos require substantial storage space, and the high capacity of SDXC cards makes them an ideal choice. The fast transfer speeds also facilitate quickly saving and viewing photos and videos.

Laptops and desktops

Many laptops and desktop computers are equipped with built-in SD card slots. An SDXC card can be used to augment the storage of these devices. This is particularly beneficial for individuals who work with large files, such as video editors and graphic designers. Some laptops and desktops might require an external card reader to utilize SDXC cards.

Gaming consoles

Modern gaming consoles, like the Nintendo Switch, utilize SDXC cards to store games and game data. The large capacity and fast transfer speeds of SDXC cards enable smooth gameplay and quick loading times.

Mobile devices

Certain smartphones and tablets support SDXC cards. They can be used to expand device storage, providing additional space for applications, photos, videos, and other data.

Drones

Drones often employ SDXC cards to store footage captured during flight. The high capacity and fast transfer speeds of SDXC cards facilitate the storage and quick transfer of high-quality drone footage.

Users must always verify device specifications to ensure support for SDXC cards before purchasing.