User's Manual

Page 13 of 31
by
USIM interface
pins in
Mini PCIe Interface
Interface
DATA RUIM_DATA 10 RUIM card data
CLK RUIM_CLK 12 RUIM card CLK
RST RUIM_RESET 14 Reset signal
VCC VREG_USIMCARD 8 RUIM card power
GND GND 4, 9, 15, 18,21, 26, 27, 29,
34, 35, 37, 40, 43, 50
GND
2.2.4.2 Reference circuit
The reference circuit of USIM interface is shown in figure 2-9.
1）The DATA line of USIM is connected to SIM power by a pull-up resistor, and the reference value is 15KΩ.
2）For avoiding the instantaneous voltage overflowing, the resistor with the reference value 22Ω can be used for the
DALA, CLK and RST. Just like the resistors R307, R308 and R309 in figure 2-8.
3）For avoiding the electro-static in USIM socket, it is recommended to use the ESD element to the DATA，CLK and
VCC. Just like the voltage dependent resistors RV301, RV302, RV303 and RV304 in figure 2-8. And the ESD
element should close to the USIM socket as close as possible.
4）For getting the more smooth USIM power supply, it is recommended to use the filter capacitors. Just like C311 and
C312 in figure 2-8, and their reference values are 33pF and 100nF.
5）In order to remove the unwanted peak signal and the elimination high frequency interference which produces on RST
and CLK, the filter capacities (C310, C309) can be placed in RST and the CLK end, the reference value is 33pF.