Specifications

M80 Hardware Design
M80_HD_V1.0 - 60 -
Table 15: Pin definition of the SIM interface
Figure 33 is the reference circuit for SIM interface, and here an 8-pin SIM card holder is used. In
order to offer good ESD protection, it is recommended to add TVS such as WILL
(http://www.willsemi.com) ESDA6V8AV6. The 22Ω resistors should be added in series between
the module and the SIM card so as to suppress the EMI spurious transmission and enhance the
ESD protection. Note that the SIM peripheral circuit should be close to the SIM card socket.
To avoid possible cross-talk from the SIM_CLK signal to the SIM_DATA signal, be careful that
both lines should be not close to each other. A useful approach is to use GND line to shield the
SIM_DATA line from the SIM_CLK line.
MODULE
SMF05C
SIM1_VDD
SIM1_CLK
SIM1_DATA
SIM1_RST
SIM_PRESENCE
VCC GND
RST VPP
CLK I/O
PRESENCE GND
100K
22R
22R
22R
1uF
VDD_EXT
MOLEX-91228
SIM CARD
GND
SIM1_GND
Figure 33: Reference circuit of the 8 pins SIM card
If customer doesn’t need the SIM card detection function, keep SIM_PRESENCE open. The
reference circuit using a 6-pin SIM card socket is illustrated as the following figure.
Name
Pin
Function
SIM1_VDD
56
Supply power for SIM Card. Automatic detection of
SIM card voltage. 3.0V±10% and 1.8V±10%. Maximum
supply current is around 10mA.
SIM1_DATA
54
SIM Card data I/O
SIM1_CLK
55
SIM Card clock
SIM1_RST
53
SIM Card reset
SIM_PRESENCE
57
SIM Card detect
SIM1_GND
52
SIM Card ground
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