SD Express brings higher card speeds

New specs for up to 4GB/s transfers

SD Cards have a new SD Express standard for faster transfers.

The SD Cards are backwards compatible with existing cards, using new interface pins.

There are no cards at the moment, nor cameras to use them.

There is a note at the foot of the article explaining some of those symbols you see on SD cards

SD 8.0 card specifications.

The new V8 specifications for SD cards offer another jump in performance at some time in the future…

Via Businesswire Tech info at SDCard

SAN RAMON, Calif.–(BUSINESS WIRE)–The SD Association announced today the SD 8.0 Specification for SD Express memory cards receives even faster transfer speeds by using the popular PCI Express® (PCIe®) 4.0 specification delivering a maximum of nearly 4 gigabytes per second (GB/s) data transfer rate. These full sized cards continue to use the NVMe Express™ (NVMe™) upper layer protocol enabling advanced memory access mechanism. As always SD Express memory cards using SD 8.0 specification maintain backward compatibility.

“SD Express’ use of even faster PCIe and NVMe architectures to deliver faster transfer speeds creates more opportunities for devices to use SD memory cards,” said Mats Larsson, Senior Market Analyst at Futuresource. “This combination of trusted and well-known technologies makes it easier for future product designs to leverage the benefits of removable storage in new ways.”

SD Express gigabyte speeds bring new storage opportunities for devices with demanding performance levels, across a variety of industries. The cards can move large amounts of data generated by data-intense wireless or wired communication, super-slow motion video, RAW continuous burst mode and 8K video capture and playback, 360 degree cameras/videos, speed hungry applications running on cards and mobile computing devices, ever evolving gaming systems, multi-channel IoT devices and automotive to name a few. SD Express will be offered on SDHC, SDXC and SDUC memory cards.

“By dramatically increasing the speeds for SD Express we’re giving device manufacturers and system developers more storage choices,” said Hiroyuki Sakamoto, SDA president. “SD 8.0 may open even more opportunities for extra high performance solutions using removable memory cards.”

“PCI-SIG® is pleased to see that SDA is continuing to adopt even faster PCIe technology configurations using PCIe 4.0 interface and dual lanes for one of the top leading removable memory cards – SD,” said Al Yanes, PCI-SIG president and chairman. “PCIe specification conformance tests are available today by major test vendors, offering a significant advantage for any new PCIe technology adopter.”

“NVMe is the industry-recognized performance SSD interface from the client to the datacenter, shipping in millions of units,” said Amber Huffman, NVM Express™ Inc. president. “Consumers will benefit by SD Association continuing the adoption of the NVMe base specification for their latest SD Express cards.”

SD Express uses the well-known PCIe 4.0 specification and the latest NVMe specification (up to version 1.4) defined by PCI-SIG and NVM Express, respectively. SD 8.0 specification provides two transfer speed options for SD Express memory cards. The two transfer speeds are accomplished by supporting either PCIe 3.0 x2 or PCIe 4.0 x1 architectures with up to ~2GB/s and with PCIe 4.0 x2 technology with up to 4GB/s. SD Express cards offering PCIe 4.0 x1 architecture use the same form factor as defined for SD 7.0 specification cards with a second row of pins to deliver transfer speeds up to 2 GB/s. SD Express cards supporting dual PCIe lanes (PCIe 3.0 x2 or PCIe 4.0 x2 technologies) have three rows of pins.

The SDA makes adoption of SD Express easy allowing companies to use existing test equipment and saving in product development costs. The SD 8.0 specification continues giving system developers access to PCIe and NVMe technologies, such as Bus Mastering, Multi Queue (without locking mechanism) and Host Memory Buffer.

[click to enlarge]

All those symbols on SD Cards

All the different names and symbols can be a bit confusing, so here’s a very short overview

Card types

• SD – The original standard
• SDHC – Capacity up to 32GB
• SDXC – Capacity up to 2TB. Higher speed UHS connections (bus) introduced

The logo shows what sort of card it is:

Update: SDUC is added to the list (128TB max) – see the announcement news article.

The Ultra High Speed (UHS) bus

Introduced with SDXC (indicated with Roman numerals)

• UHS I – Higher speed data transfer mode
• UHS II – Higher speed (than UHS I) data transfer mode using extra pins on card
• UHS III – Higher speed(than UHS II) data transfer mode using extra pins on card

Speed class ratings

This is where it can get confusing… Rather than go into all the fine detail I’ll include this table from [WP] where I’d suggest you go next if you want all the background.

Minimum sequential writing speed	Speed Class	UHS Speed Class	Video Speed Class	Application
2 MB/s	Class 2 (C2)	–	–	SD video recording
4 MB/s	Class 4 (C4)	–	–	High-definition video (HD) recording including Full HD (from 720p to 1080p/1080i)
6 MB/s	Class 6 (C6)	–	Class 6 (V6)
10 MB/s	Class 10 (C10)	Class 1 (U1)	Class 10 (V10)	Full HD (1080p) video recording and consecutive recording of HD stills (High Speed bus, Class C10), real-time broadcasts and large HD video files (UHS bus, Classes U1 and V10)
30 MB/s	–	Class 3 (U3)	Class 30 (V30)	1080p and 4K video files at 60/120 fps (UHS bus)
60 MB/s	–	–	Class 60 (V60)	8K video files at 60/120 fps (UHS bus)
90 MB/s	–	–	Class 90 (V90)

This is from Keiths Prograde SDXC card reader review