SimCom SIM800C User Manual

Smart Machine Smart Decision
SIM800C_Hardware_Design_V1.02 32 2015-4-27
M odule
PRESENCE
100nF
M O LE X-91228
SIM Card
22pF
VCC
GND
RST
VPP
CLK I/O
GND
VDD_EXT
SIM _VDD
SIM _RST
SIM _CLK
SIM _DATA
4.7K
ESDA6V1
SIM _DET
51Ω
51Ω
51Ω
Figure 30: Reference circuit of the 8-pin SIM card holder
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.
Module
SIM Card
VCC
GND
RST
VPP
CLK
I/O
C 707 10M 006 512 2
22pF
100nF
SIM _VDD
SIM _RST
SIM _CLK
SIM _DATA
SIM _DET
ESDA6V1
51Ω
51Ω
51Ω
Figure 31: 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:
 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 51 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.

SimCom SIM800C Specifications

General

Brand	SimCom
Model	SIM800C
Category	Control Unit
Language	English