SD Card Interface Description
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
3-15
NOTE
: The device size indicates the user area size. It does not include the protected area that is used for security applications
and is about 1 percent of the total card size.
The following sections describe the CSD fields and the relevant data types. If not explicitly defined otherwise, all
bit strings are interpreted as binary coded numbers starting with the left bit first.
CSD_STRUCTURE
—describes the version of the CSD structure.
Table 3-11. CSD Register Structure
CSD_STRUCTURE
CSD Structure Version
Valid for SD Card Physical
Specification Version
0
CSD version No. 1.0
Version 1.0-1.01
1-3 Reserved
TAAC
—Defines the asynchronous part (relative to the SD Card clock (CLK)) of the read access time.
Table 3-12. TAAC Access Time Definition
TAAC Bit
Position
Code
2:0 time
unit
0=1ns, 1=10ns, 2=100ns, 3=1µms, 4=10µms, 5=100µms, 6=1ms, 7=10ms
6:3 time
value
0=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
7 Reserved
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 clock dependent part of the read access time is 25.5k clock
cycles.
The total read access time N
AC
as expressed in the Table 5-17 is the sum of TAAC and NSAC. It has to be computed
by the host for the actual clock rate. The read access time should be interpreted as a typical delay for the first data
bit of a data block from the end bit on the read commands.
TRAN_SPEED
—Table 3-13 defines the maximum data transfer rate TRAN_SPEED.
Table 3-13. Maximum Data Transfer Rate Definition
TRAN_SPEED Bit
Code
2:0
transfer rate unit
0=100kbit/s, 1=1Mbit/s, 2=10Mbit/s, 3=100Mbit/s, 4... 7=reserved
6:3 time
value
0=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
7 Reserved
CCC
—The SD Card command set is divided into subsets (command classes). The card command class register
CCC defines which command classes are supported by this card. A value of ‘1’ in a CCC bit means that the
corresponding command class is supported. Table 3-14 lists the supported card command classes; refer to Table 4-2
for command class definitions.