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4.10.2 SIM Card Design Consideration
SIM card circuit is susceptible to interference, causing the SIM card failures or some other situations, so it is
strongly recommended to follow these guidelines while designing:
z Make sure that SIM card holder should far away from GSM antenna while in PCB layout.
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 holder’s GND connect to main ground directly.
z Shielding the SIM card signal by ground well.
z Recommended to place a 1uF capacitor on VSIM line and keep close to the holder.
Add some TVS and the parasitic capacitance should not exceed 50pF, and 22 resistor in serials the SIM signal
could enhance ESD protection.
4.10.3 Design Considerations for SIM Card Holder
For 8 pins SIM card holder, SIMCom recommends to use Molex 91228.User can visit http://www.molex.com
for
more information about the holder.
Figure 38: Molex 91228 SIM card holder
SIM808_Hardware Design_V1.00 2014.03.27
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