Quectel SC200L-EM Hardware Design page 37

SD_CLK 39
SD_CMD 40
SD_DATA0 41
SD_DATA1 42
SD_DATA2 43
SD_DATA3 44
SD_DET 45
SD_VDD 38
A reference circuit for the SD card interface is shown below.
SD_DATA2
SD_DATA3
SD_CMD
SD_CLK
SD_DATA0
SD_DATA1
SD_DET
GND
Module
SD_VDD is a peripheral driver power supply for an SD card. The maximum drive current is 500mA.
Because of the high drive current, it is recommended that the trace width is 0.5 mm or above. In order to
ensure the stability of drive power, a 4.7μF and a 33pF capacitor should be added in parallel near the SD
card connector.
CMD, CLK, DATA0, DATA1, DATA2, and DATA3 are all high-speed signal lines. In PCB design, please
control the characteristic impedance of them to 50Ω, and do not cross them with other traces. It is
SC200L_Hardware_Design
High-speed digital clock
DO
signal of SD card
IO Command signal of SD card
IO
High-speed bidirectional
IO
digital signal lines of SD
IO
card
IO
DI SD card insertion detection
PO 3V output power supply
R7
33R
R8 33R
R9 33R
R10 33R
R11
33R
R12
33R
R13 1K
D1 D2 D3
Figure 16: Reference Circuit for SD Card Interface
SD_VDD
C1
D4 D5 D6 D7
4.7 μF
SC200L Hardware Design
50Ω characteristic impedance
Active low
Power supply for SD card
1
P1-DAT2
2
P2-CD/DAT3
3
P3-CMD
4
P4-VDD
5
P5-CLK
6
P6-VSS
7
P7-DAT0
8
P8-DAT1
9
DETECTIVE
10
GND
D8
C2
11
GND
12
33 pF
GND
13
GND
SD Card Connector
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