Smart Module Series
SC206E_Series_Hardware_Design 49 / 115
To enhance the reliability and availability of the (U)SIM card in applications, please follow the criteria
below in (U)SIM circuit design:
⚫
Place the (U)SIM card connector as close to the module as possible. Keep the trace length as short
as possible, at most 200 mm.
⚫
Keep (U)SIM card signals away from RF and VBAT traces.
⚫
Reserve a filter capacitor for USIM_VDD, and its maximum capacitance should not exceed 1
μF.
Additionally, place the capacitor near the (U)SIM card connector.
⚫
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with ground. USIM_RST also needs ground protection.
⚫
To ensure better ESD protection, it is recommended to add a TVS array with a parasitic capacitance
not exceeding 10 pF
. Add 22 Ω resistors in series between the module and (U)SIM card to suppress
EMI such as spurious transmission. Please note that the (U)SIM peripheral circuit should be close to
the (U)SIM card connector.
⚫
Add 22 pF capacitors in parallel on USIM_DATA, USIM_CLK and USIM_RST signal lines to filter RF
interference, and place them as close to the (U)SIM card connector as possible.
3.12. SD Card Interface
SD Card interface of the module supports SD 3.0 protocol. The pin definition of SD card interface is
shown below.
Table 14: Pin Definition of SD Card Interface
Pin Name
Pin No.
I/O
Description
Comment
SD_CLK
39
DO
SD card clock
50 Ω characteristic impedance.
SD_CMD
40
DO
SD card command
SD_DATA0
41
DIO
SDIO data bit 0
SD_DATA1
42
DIO
SDIO data bit 1
SD_DATA2
43
DIO
SDIO data bit 2
SD_DATA3
44
DIO
SDIO data bit 3
SD_DET
45
DI
SD card hot-plug detect
Active low.
SD_LDO21
38
PO
SD card power supply
-
SD_LDO4
32
PO
1.8/2.95 V output power for SD
card pull-up circuits
-
