Data Sheet

4.0 Power Scheme
4.1.1 Power Up Time of Card
A card shall be ready to accept the first command within 1ms from detecting VDD min. The host may use up to
74 clocks for preparation before receiving the first command.
Power up time is defined as voltage rising time from 0 volt to VDD min and depends on application parameters
such as the maximum number of SD Cards, the bus length and the characteristic of the power supply unit.
Supply ramp up time provides the time that the power is built up to the operating level (Host Supply
Voltage) and the time to wait until the SD card can accept the first command,
The host shall supply power to the card so that the voltage is reached to Vdd_min within 250ms and start to
supply at least 74 SD clocks to the SD card with keeping CMD line to high. In case of SPI mode, CS shall be held
to high during 74 clock cycles.
After power up (including hot insertion, i.e. inserting a card when the bus is operating) the SD Card enters
the idle state. In case of SD host, CMD0 is not necessary. In case of SPI host, CMD0 shall be the first command to