Lexar has announced it’s currently developing a new line of SD Express and microSD Express cards, despite no camera currently supporting the standard.
The cards, which use the SD 7.0 specification (PCIe 3.1 x 1 lane), will offer read and write speeds of 824MB/s and 410MB/s, respectively. The maximum bandwidth for the cards is 985MB/s, nearly triple that of the current UHS-II SD and microSD cards. This development also suggests Lexar (and, perhaps, the whole industry) is skipping the entirety of the UHS-III interface and going straight to PCIe/NVMe: the same interface CFexpress cards use.*
Lexar says the new SD Express and microSD Express cards will be built on Silicon Motion’s SM 2708 controller and are backwards compatible, albeit with a major caveat. The controller inside the SD Express and microSD Express cards is limited to UHS-I speeds (SD 6.1 up to V30, U3), even when used in UHS-II card slots. So, even though these will technically work with cameras that support UHS-II class SD cards, you’ll only get UHS-I speeds (100MB/s).
As for capacity, Lexar notes the SD Express cards will come in capacities up to 512GB while the microSD Express cards will top out at 256GB.
It’s an interesting move from Lexar. The press release announcing the development specifically references the photographic and video capabilities of these cards, but as it stands there’s nothing on the market that supports them. Could Lexar know more than we do in terms of what card formats future cameras will use? Possibly, but it could also be a bet that the popularity of the SD format (and name) will prevail over the likes of CFexpress cards, at least for the bulk of the market.
CFexpress Type-B cards used by Canon, Nikon and Panasonic for now promise greater speed, thanks to their two-lane design, but Lexar’s SD Express cards should be a match for the smaller CFexpress Type-A cards currently only used by Sony, risking one or other format ending up as another Memory Stick or xD-style developmental dead-end. The SD Association has already set out a faster two-lane PCIe 4.0 specification, that could offer CFexpress Type-B levels of performance, though won’t necessarily offer the same capacities or levels of durability that the larger CFe cards can offer.
Whatever the case, we should know soon enough, as Lexar says it’s planning to launch the lineup in 2022.
* In theory, these cards could be compatible with Sony cameras that support CFexpress Type A, as they use the single-lane PCIe 3.0 interface. But there could be other elements at play effecting compatibility. We have contacted Sony for information as to whether or not a future firmware could, at least in theory, make these cards compatible with Sony CFexpress cameras.