In the specification are defined 6.0 SD speed class Class 2 Application Performance and interface support LVS
In November last year, the organization SD Association has introduced a new speed class, defining it in the specification SD Specification 5.1. A new speed class called the Application Class shows guaranteed Performance capabilities of the card at the parts store and run applications. The first rules of App Performance Class 1 or A1. Card with such a designation needs to ensure that performance is not below 1500 IOPS on read operations random access of not less than 500 IOPS on write operations with random access. In addition, the data transfer rate for sequential operations should not be below 10 MB/s. Over time, it was planned to add to the standard and other values of the class. Judging by the new message of the SD Association, that time is now.
Another class that appeared in the specifications of SD 6.0, predictable Application Performance is called Class 2 (A2). Labelling on the memory card will indicate that the read operations random access is provided performance is not below 4000 IOPS, and on write operations with random access — not less than 2000 IOPS. Products marked A2 must support the command queue, caching, and background «self-service», initiated as from the side, and the controller of the card itself. At the data transfer rate for sequential operations, the class A2 is identical to A1, then there is guaranteed speed below 10 MB/s.
Another innovation is 6.0 SD interface support LVS (low voltage signaling) with a voltage level of 1.8 V, allowing to reduce power consumption. The device to the host LVS must be marked LV. With this equipment, you should use the card LVS, such as a map, marked A2, which necessarily must support LVS. Note that the card LVS can be used with equipment that was not marked LV, that is designed for a voltage of 3.3 V.
Source: SD Association