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SD_LDO11 is the power supply for the SD card and can provide up to 800 mA output current. Due to the
high output current, it is recommended that the trace width should be at least 0.8 mm. In order to ensure
stability of output current, add a 4.7 μF and a 33 pF capacitor in parallel near the SD card connector.
SD_CMD, SD_CLK, SD_DATA0, SD_DATA1, SD_DATA2, and SD_DATA3 are all high-speed signal lines.
In PCB design, control the characteristic impedance of them to 50 Ω, and do not cross them with other
traces. It is recommended to route the traces on the inner layer of PCB and keep them of the same length.
Additionally, SD_CLK needs ground shielding separately.
Layout guidelines:
⚫
Control the impedance to 50 Ω ± 10 % and add ground shielding.
⚫
The trace length difference between SD_CLK and other signal traces like SD_CMD and SD_DATA
should not exceed 1 mm.
Table 17: SD Card Trace Length Inside the Module
Pin No.
39
40
41
42
43
44
SC200R&SC262R_Series_Hardware_Design
Signal
SD_CLK
SD_CMD
SD_DATA0
SD_DATA1
SD_DATA2
SD_DATA3
Smart Module Series
Length (mm)
21.50
21.40
21.45
21.60
21.40
21.35
55 / 124
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