Silicon Motion has introduced their first SD Card controller to help the NVMe-based SD Express interface. The new SM2708 controller is able to sequential switch speeds of 1700 MB/s, vastly greater than the 104 MB/s most SD units and playing cards are restricted to utilizing the older however widely-supported UHS-I interface.
In 2018, model 7.zero of the SD specification launched the PCIe and NVMe-based SD Express interface as the brand new manner ahead for SD playing cards. The older UHS-II and UHS-III interfaces developed in variations four via 6 of the SD commonplace and able to speeds from 156 MB/s to 624 MB/s have been deserted in favor of a single lane of PCIe gen3 (~985 MB/s). Last 12 months, model 8.zero of the SD specification added help for PCIe gen4 speeds and a second PCIe lane, bringing the theoretical most switch pace as much as nearly four GB/s.
Silicon Motion’s SM2708 is a two-lane controller, however nonetheless utilizing PCIe gen3 pace, therefore the highest pace cannot fairly attain 2 GB/s. This has the potential to convey SD card efficiency as much as close to the degrees of entry-level client NVMe SSDs for laptops and desktops—aggressive with SSDs primarily based on slightly-outdated controllers just like the Phison E8T or Silicon Motion SM2263XT. The SM2708 controller makes use of two NAND channels as an alternative of the 4 usually utilized by entry-level SSD controllers, however the SM2708 is able to a 1200 MT/s IO pace that enables it to get good efficiency out of current NAND flash generations with out the facility and measurement penalties of a four-channel answer.
In 2019, Silicon Motion’s major competitor Phison introduced their PS5017 SD Express controller. This relies on the sooner SD 7.zero specification and thus is a PCIe three x1 design and restricted to about 870 MB/s. In February 2021 Phison introduced they have been about to begin transport playing cards primarily based on this answer. Silicon Motion’s SM2708 controller may not take that lengthy to show into precise merchandise, however they clearly have missed out on the primary spherical of SD Express competitors—although they are able to leapfrog Phison’s answer.
Underlying all of the developments associated to current flash reminiscence card requirements has been the problem of poor adoption. For years, storage tech has been advancing a lot sooner than digicam tech. Storage expertise corporations stand prepared to produce extra superior reminiscence playing cards, however they can not succeed available in the market until there are host units prepared to make use of the upper efficiency. We’ve seen a decade of failed successors to the previous SD and CF requirements that now appear pitifully gradual. SD’s UHS-II and UHS-III, CF’s CFast and XQD, and UFS playing cards have all been demonstrated as working applied sciences and all ultimately made it to market to some extent, however with very restricted success. The SD and CF worlds have converged on PCIe and NVMe as the way in which ahead, adopting interfaces that have already got a thriving ecosystem and long-term viability in different type components. That makes it extra seemingly that requirements like SD Express will truly catch on, however it might nonetheless be a number of years earlier than PCIe-based interfaces are supported on any telephones or greater than a handful of high-end cameras.
