SanDisk SD Card - OEM Product Manual

Interface Description

11/2010, Version 2.9. © 2007 - 2010 SanDisk Corporation. SanDisk Confidential, subject to all applicable non-disclosure agreements

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The recommended power control scheme for SanDisk SD card is illustrated in Figure 3-1. Most

card connectors have a card detect switch that signals the SD host when the card is inserted.

After the host is aware of the card insertion, it turns on the FET switch to apply power to card's

VDD pin.

Once the card is inserted and all card pins are making contact, there is a delay before the FET

switch is turned on.

IMPORTANT: Because there are clamping diodes on the CMD, CLK, and DAT0-3 pins, it is

crucial to ensure that CLK, CMD, and DAT0-3 are at zero (0) volts during the delay and before

the FET switch is turned on. If any I/O pin, (CMD, CLK, or DAT0-3) goes above zero volts

during the delay and before power reaches the card VDD pin, it will forward bias the clamping

diodes and can cause the card to go into an unknown state.

It is the host's responsibility to make sure power gets to VDD before CMD, CLK, or DAT0-3 go

above zero volts.

3.4.2

Bus Operating Conditions

SPI Mode bus operating conditions are identical to SD Card Bus Mode operating conditions. For

details, see Section 6.6 of the SDA Physical Layer Specification, Version 3.01.

3.4.3

Bus Timing (Standard Mode)

See Section 6.7 of the SDA Physical Layer Specification, Version 3.01.

3.5

SD Card Registers

There is a set of eight registers within the card interface. However, the DSR Register is optional

and is not used in SanDisk SD Card. For specific information about all registers, refer to Section

5 of the SDA Physical Layer Specification, Version 3.01.

3.5.1

Operation Conditions Register

The Operation Conditions Register (OCR) stores a card's VDD voltage profile. Refer to Section

5.1 of the SDA Physical Layer Specification, Version 3.01 for more information.

3.5.2

Card Identification Register

The Card Identification (CID) Register is 16 bytes long and contains the unique card

identification number. It is programmed during card manufacturing and cannot be changed by

card hosts. See Table 3-4.