If you’re in the market for a new SD card, you’ll run into quite a few specifications before choosing a correct SD card for your DSLR, video camera or drone. 

One of the more complex features the SD Association has released is Ultra High-Speed (UHS) bus interface. Evolving from normal SD card speeds (High-Speed), UHS SD cards has increased the potential data transfer speeds to meet the demands of modern high-speed devices.

What is Ultra High-Speed (UHS)?

Ultra High-Speed (UHS) is the new generation bus interface for SD cards. Succeeding the regular high-speed specification, UHS was recently designed to support devices with higher capacity and speed requirements.

In addition to handling higher memory card capacity, UHS standard raises the bar for faster data transfer rates, increasingly important when shooting high-resolution videos and large, RAW format images. To meet high demands of modern devices, UHS specification includes three versions: UHS-I, UHS-II, and UHS-III. These range in speed from an impressive 104 Mb/s to a jaw-dropping 624 Mb/s.

Differences between UHS-I, UHS-II, and UHS-II

UHS-I bus interface, with transfer rates up to 104 Mb/s, debuted as the first upgrade from normal, high-speed specification.

Next, came UHS-II, which bumped up the speeds to 312 Mb/s. Perhaps the most prominent difference from its first version, was the added 2^nd row pins, which uses Low Voltage Differential Signaling (LVDS) technology to allow higher transfer rates.

Most recently, UHS-III specification was announced in earlier 2017, doubling previous UHS-II rates for insane data transfer speeds up to 624 Mb/s. UHS-III specification carries two lane, LVDS technology and uses new QR (Quick Recovery) function for improved power management to reduce its transition time from Dormant to Active. This optimizes your camera's power consumption, especially useful in shooting time-lapse, burst mode or extended videos.