11.2.2 Design Layout Recommendations

When designing the SD Card interface, consider the following recommendations:

• Apply impedance control of 50 Ohms on the clock and data interfaces.
• Match signal lengths to within 20 mils. Affected PIOs in the example above are PA15 to PA20.
• Place the clock line (PA17) at least three times the trace width away from other signals for noise immunity.
• Place data signals at least two times the trace width away from any other data traces.
• Place data signals at least one trace width away from any copper plane.