Smart Machine Smart Decision
Module
SIM Card
VCC
GND
RST
VPP
CLK
I/O
C707 10M 006 512 2
22pF
100nF
SIM_VDD
SIM_RST
SIM_CLK
SIM_DATA
SIM_DET
ESDA6V1
51Ω
51Ω
51Ω
Figure 34: Reference circuit of the 6-pin SIM card holder
4.8.2. SIM Card Design Guide
SIM card signal could be interferenced by some high frequency signal, it is strongly recommended to follow
these guidelines while designing:
z
SIM card holder should be far away from GSM antenna
z
SIM traces should keep away from RF lines, VBAT and high-speed signal lines
z
The traces should be as short as possible
z
Keep SIM card holder’s GND connect to main ground directly
z
Shielding the SIM card signal by ground well
z
Recommended to place a 100nF capacitor on SIM_VDD line and keep close to the SIM card holder
z
Add some TVS which parasitic capacitance should not exceed 50pF
z
Add 51Ω resistor to (SIM_RST/SIM_CLK/SIM_DATA) signal could enhance ESD protection
4.8.3. Design Considerations for SIM Card Holder
For 8 pins SIM card holder, SIMCom recommends to use Molex 91228.Customer can visit
http://www.molex.com
for more information about the holder.
