Smart Module Series
SC200K_Series_Hardware_Design 51 / 105
VDDSD is the power supply for SD card. The maximum drive current is 400 mA. Because of the large
drive current, it is recommended that the trace width is 0.5 mm or above. To ensure the stability of drive
power, add 4.7 μF and 33 pF capacitors 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 impedance of them a
s 50 Ω ±10 %, and do not cross them with other traces.
Meanwhile, it is recommended to route these traces on the inner layer of PCB, and keep them of the
same length. Additionally, SD_CLK needs separate ground shielding.
Trace length requirements:
⚫
Control impedance as
50 Ω ±10 %, and add ground shielding.
⚫
The trace length difference between SD_CLK and SD_CMD/SD_DATA should be less than 1 mm.
Table 15: SD Card Signal Trace Length Inside Module
Pin No.
Pin Name
Length (mm)
39
SD_CLK
34.25
40
SD_CMD
36.32
41
SD_DATA0
33.27
42
SD_DATA1
32.71
43
SD_DATA2
32.63
44
SD_DATA3
33.36
1. The maximum output current of VDDSD is 400 mA. It is suggested to add an LDO with output
current of 1 A if an external large-capacity SD card is needed.
2. VDDSDIO is only used for pulling up SD_DATA and SD_CMD and cannot supply power to other
peripherals.
NOTE
