The SD Association has announced a new SD Express speed class that guarantees microSD Express memory card write speeds to 2GB/s. In addition, the new SD9.1 specifications increase multi-stream access abilities and thermal regulation features with subsequent write performances.
The latest generation microSD Express utilizes one PCIe Gen 4 lane to achieve speeds of 1,969MB/s, in line with the latest microSD Addendum version 8 specifications.
The SD7.1 specification features a maximum data transfer rate of 985MB/s and the NVMe upper layer protocol.
The increased speed gives product designers more storage options, enabling them to deliver SSD-level performance to a wide variety of size-constrained devices that require easily repairable or upgradeable storage.
SD Express Speed Class is limited to SDXC, SDUC, and microSDUC memory cards with an SD Express pass. This is the most significant technological evolution since the SD standard’s inception in 2000, supporting controller, memory, application and interface performance requirements to meet evolving market needs.
SD Express supports usage models that require faster removable or semi-removable memory cards, and is also well-suited for “right to repair” support.
SDA President Hiroyuki Sakamoto commented as follows:
By defining minimum guaranteed sequential performance standards for SD Express memory cards, SDA helps both device manufacturers and users achieve the highest quality recording and playback of all types of content.
By doubling the speed of microSD Express to 2GB/s, SDA offers product manufacturers more storage options and a card that can be used in a variety of demanding storage applications, as well as an environmentally friendly card. Easier repairs and upgrades, thats the idea with these cards.
New Functions with SD Express
To optimize the performance of the SD Express speed class under various power levels and thermal conditions, the NVMe specification was introduced to define multiple power management settings through maximum power (MP) values.
For card thermal management, if the host device consumes power up to the set MP value, it provides thermal management function with a specific temperature threshold group.
Additionally, the host device can set the appropriate thermal management parameters for the card depending on the target speed class and PCIe path mode.
The SD9.1 specification defines the access rules necessary to ensure PCI/NVMe interface performance, including up to eight multi-stream accesses.
SDA has prepared a white paper detailing the new features and speed classes defined in SD9.1.