H330SS LGA Module Hardware User Manual Page 30 of 38
5.6.2
USIM Design
Reference design:
Figure 5-8
Note:
For better EMC performance, SIM card position should be close to module
Filtering capacitor should be close to SIM card pin
The interface need add ESD protection, ESD should be close to SIM card pin
USIM_IO is already pulled up inside the module,
USIM_CD support SIM hot plug, low level is effective, if low level is detected, this means SIM card is
inserted.
5.6.3
USIM Design Notice
The SIM interface and signals design is extremely important for proper operation of the SIM card.
There are several design guidelines that must be followed:
The layout signals of the SIM card should be away from any possible EMI
interference
To ensure signal integrity, the length between SIM interface signals and module should not exceed 100
mm
sources, such as the RF
antenna and digital switching signals.
To avoid crosstalk between USIM_CLK and USIM_IO, it is recommended to route them separately on the
application board, and preferably isolated by a surrounding ground plane.
The SIM card signals should be protected from ESD using very low capacitance protective elements (like
Zener diode). The recommended part no of ESD is AVR-M1005C080MTAAB (TDK). ESD component should
layout with SIM hold closely.
