Sim Card Design Guide; Design Considerations For Sim Card Holder - SimCom SIM800C Hardware Design

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The SIM_DET pin is used for detection of the SIM card hot plug in. Customer can select the 8-pin SIM card
holder to implement SIM card detection function. AT command "AT+CSDT" is used to enable or disable SIM
card detection function. For details of this AT command, please refer to document [1].
If the SIM card detection function is not used, customer can keep the SIM_DET pin open. The reference circuit
of 6-pin SIM card holder is illustrated in the following figure.
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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:
 SIM card holder should be far away from GSM antenna
 SIM traces should keep away from RF lines, VBAT and high-speed signal lines
 The traces should be as short as possible
 Keep SIM card holder's GND connect to main ground directly
 Shielding the SIM card signal by ground well
 Recommended to place a 100nF capacitor on SIM_VDD line and keep close to the SIM card holder
 Add some TVS which parasitic capacitance should not exceed 50pF
 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.
SIM800C_Hardware_Design_V1.02
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22pF
Figure 30: Reference circuit of the 8-pin SIM card holder
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22pF
Figure 31: Reference circuit of the 6-pin SIM card holder
M O LE X -91228
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51Ω
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51Ω
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51Ω
100nF
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51Ω
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51Ω
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C 707 10M 006 512 2
51Ω
E S D A 6V 1
100nF
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2015-4-27