Smart Module Series
SC690A_Series_Hardware_Design 52 / 105
SD_LDO22 is a peripheral driver power supply for SD card. The maximum drive current is 600 mA.
Because of the high drive current, it is recommended that the trace width is 0.5 mm or above. To ensure
the stability of drive power, 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
traces. In PCB design, control the characteristic impedance of them as
50 Ω, and do not cross them with
other traces. 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.
Layout guidelines:
⚫
Control impedance to
50 Ω ±10 %, and add ground shielding.
⚫
The trace length difference between SD_CLK and other traces like SD_CMD and SD_DATA should
be less than 1 mm.
Table 16: SD Card Signal Trace Length Inside the Module
4.5. GPIO Interfaces
The module has abundant GPIO interfaces with power domain of 1.8 V. The pin definition is listed below.
Table 17: Pin Definition of GPIO Interfaces
Pin No.
Signal
Length (mm)
70
SD_CLK
48.98
69
SD_CMD
48.82
68
SD_DATA0
48.42
67
SD_DATA1
48.54
66
SD_DATA2
48.60
65
SD_DATA3
50.34
Pin Name
Pin No.
I/O
Description
Comment
GPIO_2
248
DIO
General-purpose
input/output
