SD – Secure Digital

A Secure Digital Memory Card is a digital storage medium based on the use of
so-called flash memory cells.

In general, an SD card works like a RAM component in a PC. The difference is that
flash memories do not lose their information as soon as they are disconnected from a power source but
store them permanently.

      Multi-level cell     Single-level cell
Abbreviation     MLC     SLC
Number of bits per memory cell     More than 1 bit     1 bit
1 GB of storage capacity     approximately 2 billion memory cells     approximately 9 billion memory cells
Maximum number of writes     approximately 10,000 per memory cell     approximately 100,000 per memory cell

Speed class

The speed class defines the minimum write speed of SD cards. The SD Association currently defines the speed classes as follows:

Class Speed
Class 2 2 MB/s
Class 4 4 MB/s
Class 6 6 MB/s
Class 10 10 MB/s

Grades

Industrial grade

Automotive grade

Consumer grade

SLC flash memory cell

MLC flash memory cells

MLC flash memory cells

dynamic, static wear levelling methods

dynamic, static wear levelling methods

Standard wear levelling

extended specifications

extended specifications

standard specifications

extended product service

extended product service

standard product service

fixed BOM (bill of materials)

fixed BOM (bill of materials)

extremely temperature-resistant

dustproof

waterproof (IP67)

05.02.2014

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