Sd Bus Topology - SanDisk SDSDB-32-201-80 - Industrial Grade Flash Memory Card Product Manual

3.2. SD Bus Topology

The SD bus has six communication lines and three supply lines:
CMD—Command is a bi-directional signal. (Host and card drivers are operating in push pull mode.)
DAT0-3—Data lines are bi-directional signals. (Host and card drivers are operating in push pull
mode.)
CLK—Clock is a host to cards signal. (CLK operates in push pull mode.)
VDD—VDD is the power supply line for all cards.
VSS[1:2]—VSS are two ground lines.
SanDisk Secure Digital (SD) Card Product Manual, Rev. 1.9 © 2003 SANDISK CORPORATION
Figure 3-1. SD Card Architecture
SD Card Interface Description
3-3