SanDisk microSD™, microSDHC™ and microSDXC™ cards
OEM Product Manual
2.5
January 2012 Version 2.5 © 2008 - 2012 SanDisk Corporation. SanDisk Confidential, subject to all applicable non-disclosure agreements
10
3 I
NTERFACE
D
ESCRIPTION
3.1
Pins and Registers
The SanDisk microSD™ Card Product Family has exposed contacts on one side. The
host uses a dedicated connector to connect to microSD cards.
In Table 4, pin assignments for the SanDisk microSD Card are described for SD Bus
Mode and SPI Bus Mode
Note: Pin assignments are provided by the SDA Physical Layer Specification,
Version 3.01 and associated addendums (microSD). For more details, refer to Section
3.7 of the SDA Physical Layer Specification, Version 3.01
Table 4: SD Bus Mode Pin Assignment
Pin No.
SD Mode
SPI mode
Name
Type
1
Description
Name
Type
1
Description
1 DAT2
2,5
I/O/PP
Data Line [bit 2]
RSV
-
Reserved
2 CD/DAT3
2
I/O/PP
3
Card Detect/Data Line [bit 3]
CS
I
3
Chip select (active low)
3 CMD PP
Command/Response DataIn
I
Data
In
4 V
DD
S
Supply
Voltage
V
DD
S
Supply
Voltage
5 CLK I
Clock
SCLK
I Clock
6 V
SS
S
Supply voltage ground
V
SS
S
Supply
voltage
ground
7
DAT0
I/O/PP
Data Line [bit 1]
DataOUT
O/PP
Data Out
8 DAT1
2,4
I/O/PP
Data Line [bit 2]
RSV
4
- Reserved
Notes: 1.
Type Key: S=power supply; I=input; O=output using push-pull drivers; PP=I/O using
push-pull drivers.
2.
The extended DAT lines (DAT1-DAT3) are input on power up. They start to
operate as DAT lines after the SET_BUS_WIDTH command. It is the responsibility
of the host designer to connect external pull-up resistors to all data lines even if
only DAT0 is to be used. If not, there may be unexpected high current consumption
due to the floating inputs of DAT1 & DAT2 (if they are not used).
3.
At power up this line has a 50KOhm pull-up enabled in the card. This resistor
serves two functions: Card Detection and Mode Selection. For Mode Selection, the
host can drive the line high or let it be pulled high to select SD mode. If the host
wants to select SPI mode, it should drive the line low. For Card Detection, the host
detects that the line is pulled high. The user should disconnect this pull-up with
SET_CLR_CARD_DETECT (ACMD42) command during regular data transfer.
4.
DAT1 line may be used as Interrupt Output (from the Card) in SDIO mode during
all the times that it is not in use for data transfer operations.
5.
DAT2 line may be used as Read Wait signal in SDIO mode.
