SanDisk SD Card

Revision 2.2Chapter 3 – SD Card Interface DescriptionSD Card Product ManualThe following sections describe the CSD fields and the relevant data types. If not explicitlydefined otherwise, all bit strings are interpreted as binary coded numbers starting with theleft bit first.• CSD_STRUCTURE—describes the version of the CSD structure.Table 3-12 CSD Register StructureCSD Structure CSD Structure Version Valid for System Specification Version0 CSD Version 1.0 v1.0 to v1.101-3 Reserved ---• TAAC—defines the asynchronous part (relative to the SD Card clock (CLK)) of theread access time.Table 3-13 TAAC Access Time DefinitionTAAC Bit Position2:0Time exponentCode0=1 ns, 1=10 ns, 2=100 ns, 3=1 us, 4=10 us, 5=100 us, 6=1 ms, 7=10 ms6:3Time value7 Reserved0=reserved, 1=1.0, 2=1.2, 3=1.3, 4=1.5, 5=2.0, 6=2.5, 7=3.0, 8=3.5, 9=4.0,A=4.5, B=5.0, C=5.5, D=6.0, E=7.0, F=8.0• NSAC—Defines the worst case for the clock dependent factor of the data access time.The unit for NSAC is 100 clock cycles. Therefore, the maximal value for the clockdependent part of the read access time is 25.5k clock cycles.The total read access time N AC is the sum of TAAC and NSAC. It has to be computedby the host for the actual clock rate. The read access time should be interpreted as atypical delay for the first data bit of a data block from the end bit on the readcommands.• TRAN_SPEED—Table 3-14 defines the maximum data transfer rate TRAN_SPEED.Table 3-14 Max. Data Transfer Rate DefinitionTRAN_SPEED Bit2:0Transfer rate exponentCode0=100 kb/s, 1=1 Mb/s, 2=10 Mb/s, 3=100 Mb/s, 4…7=reserved6:3Time mantissa7 Reserved0=reserved, 1=1.0, 2=1.2, 3=1.3, 4=1.5, 5=2.0, 6=2.5, 7=3.0, 8=3.5, 9=4.0,A=4.5, B=5.0, C=5.5, D=6.0, E=7.0, F=8.0• CCC—The SD Card command set is divided into subsets (command classes). TheCard Command Class Register (CCC) defines which command classes are supportedby this card. A value of “1” in a CCC bit means that the corresponding command classis supported.© 2004 SanDisk Corporation 3-15 12/08/04