18
/
50
GND
USIM_RST
USIM_CLK
USIM_DATA
22R
22R
22R
100nF
(U)SIM Card Connector
GND
VCC
RST
CLK
IO
VPP
GND
15K
Module
USIM_VDD
USIM_VDD
Figure 4: Reference Circuit of (U)SIM Card Interface with a 6-pin (U)SIM Card Connector
In order to enhance the reliability and availability of the (U)SIM card in customers’ application, please
follow the criteria below in (U)SIM circuit design:
Keep layout of (U)SIM card as close to the module as possible. Keep the trace length as less than
200mm as possible.
Keep (U)SIM card signal away from RF and power supply traces.
Keep the trace width of ground and USIM_VDD no less than 0.5mm to maintain the same electric
potential. The decouple capacitor of USIM_VDD should be less than 1uF and must near to (U)SIM
card connector.
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with surrounded ground.
In order to offer good ESD protection, it is recommended to add a TVS whose parasitic capacitance
should not be more than 50pF. The 22 ohm resistors should be added in series between the module
and the (U)SIM card so as to suppress EMI spurious transmission and enhance ESD protection.
Please note that the (U)SIM peripheral circuit should be close to the (U)SIM card connector.
The pull-up resistor on USIM_DATA line can improve anti-jamming capability when long layout trace
and sensitive occasion are applied, and should be placed close to the (U)SIM card connector.
3.5.
USB Interfaces
The following table shows the pin definition of USB 2.3&3.0 interfaces.
