==========
 SD cards
==========
.. contents::
   :local:

Standards
=========

======= =========== ====== ======= =============== ==================
Acronym Capacity    FS     Spec    Compatibility   Name
======= =========== ====== ======= =============== ==================
SD      128MB-2GB   FAT16          SD, SDHC, SDXC
SDHC    4-32 GB     FAT32  SDA 2.0 SDHC, SDXC      High Capacity
SDXC    64GB-2TB    exFAT  SDA 3.0 SDXC            Extended Capacity
======= =========== ====== ======= =============== ==================

Ultra High Speed, Phase I (UHS-I):
* 50MB/s (UHS-50)
* 104MB/s (UHS-104)

Ultra High Speed Phase II (UHS-II):
* 156MB/s
* 312MB/s

Speed
=====

SD Speed Class (a number inside "C" symbol) write speed:

====== =========
Class  Min Speed
====== =========
2      2MB/s
4      4MB/s
6      6MB/s
8      8MB/s
10     10MB/s
====== =========

UHS Speed Class (a number inside "U" symbol) write speed:

====== =========
Class  Min Speed
====== =========
1      10MB/s
3      30MB/s
====== =========

Video Speed Class (a number after "V" symbol) write speed:

====== =========
Class  Min Speed
====== =========
6      6MB/s
10     10MB/s
30     30MB/s
60     60MB/s
90     90MB/s
====== =========

.. note:: UHS-I bus interface can only support V6 to V30 speed class memory cards. UHS-II is
          required for V60, V90.

Express Speed Class (a number after "E" symbol) write speed:

====== =========
Class  Min Speed
====== =========
150    150MB/s
300    300MB/s
450    450MB/s
600    600MB/s
====== =========

Video resolution minimum requirements:

================== ==============
Video resolution   Speed class
================== ==============
640x480   (SD)     C2, C4, U1, V6
1920x1080 (FullHD) C6, U1, V6
4k                 C10, U1, V10
8k                 V60
================== ==============

https://support-in.wd.com/app/answers/detailweb/a_id/36273/~/specifications-and-compatibility-for-sd%2Fsdhc%2Fsdxc-memory-cards
  Specifications and Compatibility for SD/SDHC/SDXC Memory Cards.
https://www.kingston.com/en/blog/personal-storage/memory-card-speed-classes
  A guide to speed classes for SD and microSD Cards.