SanDisk SD Card

Revision 2.2Chapter 3 – SD Card Interface DescriptionSD Card Product ManualAfter power up, the host starts the clock and sends the initializing sequence on the CMDline. This sequence is a contiguous stream of logical ‘1’s. The sequence length is themaximum of 1msec, 74 clocks or the supply-ramp-up-time; the additional 10 clocks (overthe 64 clocks after what the card should be ready for communication) is provided toeliminate power-up synchronization problems.Every bus master shall have the capability to implement ACMD41 and CMD1. CMD1 willbe used to ask MultiMediaCards to send their operation conditions. In any case theACMD41 or the CMD1 shall be send separately to each card accessing it through its ownCMD line.3.4.2 Bus Operating ConditionsSPI Mode bus operating conditions are identical to SD Card mode bus operatingconditions. Table 3-4 lists the power supply voltages. The CS (chip select) signal timing isidentical to the input signal timing (see Figure 3-8).Table 3-4Bus Operating Conditions SummaryParameter Symbol Min Max Unit RemarkGeneralPeak voltage on all lines --- -0.3 V DD + 0.3 VAll InputsInput Leakage Current --- -10 10 uAAll OutputsOutput Leakage Current --- -10 10 uAPower Supply Voltage 7Supply Voltage V DD 2.0 3.6 V CMD0, 15, 55,ACMD41 commandsV DD 2.7 3.6 V Except CMD0, 15, 55,ACMD41 commandsSupply voltage differentials(V SS1 , V SS2 )--- -0.3 0.3 VPower-up Time --- --- 250 mS From 0 V to V DD min.3.4.3 Bus Signal Line LoadThe total capacitance, C L , of the clock line in the SD Card bus is the sum of the bus-mastercapacitance (C HOST ), the bus capacitance (C BUS ) itself and the capacitance (C CARD ) of eachcard connected to this line:C L = C HOST + C BUS + N*C CARDWhere N is the number of connected cards. Requiring the sum of the host and buscapacitances not to exceed 30 pF for up to 10 cards, and 40 pF for up to 30 cards, thevalues in Table 3-4 must not be exceeded.7 The current consumption of any card during the power-up procedure must not exceed 10 mA.© 2004 SanDisk Corporation 3-7 12/08/04