Product Info

Smart LTE Module Series
SC20 Hardware Design
SC20_Hardware_Design 49 / 130
⚫ In order to offer good ESD protection, it is recommended to add a TVS diode array with parasitic
capacitance not exceeding 50pF. The 22Ω resistors should be added in series between the module
and (U)SIM card so as to suppress EMI spurious transmission and enhance ESD protection. Please
note that the (U)SIM peripheral circuit should be close to the (U)SIM card connector.
⚫ The 33pF capacitors should be added in parallel on USIM_DATA, USIM_CLK and USIM_RST signal
lines so as to filter RF interference, and they should be placed as close to the (U)SIM card connector
as possible.
3.12. SD Card Interface
SC20 module supports SD cards with 4-bit data interfaces or SDIO devices. The pin definition of the SD
card interface is shown below.
Table 14: Pin Definition of SD Card Interface
A reference circuit for SD card interface is shown as below.
Pin Name
Pin No
I/O Description
Comment
SD_LDO11
38
PO
Power supply for SD card
Vnorm=2.95V
I
O
max=600mA
SD_LDO12
32
PO
1.8V/2.95V output power supply
Support 1.8V or 2.95V
power supply.
The maximum drive
current is 50mA.
SD_CLK
39
DO
High speed digital clock signal of SD card
Control characteristic
impedance as 50Ω.
SD_CMD
40
I/O
Command signal of SD card
SD_DATA0
41
I/O
High speed bidirectional digital signal lines
of SD card
SD_DATA1
42
I/O
SD_DATA2
43
I/O
SD_DATA3
44
I/O
SD_DET
45
DI
SD card insertion detection
Active low