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Smart LTE Module Series
SC650T Hardware Design
SC650T_Hardware_Design 54 / 131
Table 12: Pin Definition of SD Card Interface
Pin Name
Pin No.
I/O Description
Comment
SD_LDO11
63
PO
Power supply for SD card
Vnorm=2.95V
I
O
max=800mA
SD_LDO12
179
PO
SD card pull-up power
supply
Support 1.8V or 2.95V power supply.
The maximum drive current is 50mA.
SD_CLK
70
DO
High speed digital clock
signal of SD card
Control characteristic impedance as
50Ω.
SD_CMD
69
I/O
Command signal of SD card
SD_DATA0
68
I/O
High speed bidirectional
digital signal lines of SD
card
SD_DATA1
67
I/O
SD_DATA2
66
I/O
SD_DATA3
65
I/O
SD_DET
64
DI
SD card insertion detection
Active low.
A reference circuit for SD card interface is shown as below.
SD_CMD
120K
NM_51K
SD_DATA3
SD_DATA2
LDO5_1P8
SD_CLK
SD_DATA0
SD_DET
SD_DATA1
P1-DAT2
P2-CD/DAT3
P3-CMD
P4-VDD
P5-CLK
P8-DAT1
GND
P6-VSS
P7-DAT0
DETECTIVE
GND
GND
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
SD_LDO11
33R
33R
33R
33R
33R
33R
1K
33pF
4.7uF
SD_LDO12
Module
R1 R2
R3 R4
R5
R6
NM_51K
NM_10K
NM_51K
NM_51K
R7
R8
R9
R10
R11
R12
R13
D1 D2
D3
D4 D5
D6
D7
D8
C1
C2
SD Card Connector
Figure 17: Reference Circuit for SD Card Interface
SD_LDO11 is a peripheral driver power supply for SD card. The maximum drive current is approx. 800mA.
Because of the high drive current, it is recommended that the trace width is 0.5mm or above. In order to
ensure the stability of drive power, a 4.7uF and a 33pF capacitor should be added in parallel near the SD
card connector.