LTE-A Module Series
EP06 Series Hardware Design
EP06_Series_Hardware_Design 20 / 56
The following figure shows a reference design for (U)SIM card interface with a 6-pin (U)SIM card
connector.
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’ applications, please
follow the criteria below during (U)SIM circuit design:
Place the (U)SIM card connector as close to the module as possible. Keep the trace length as less
than 200 mm as possible.
Keep (U)SIM card signals away from RF and power supply traces.
Keep the trace width of ground and USIM_VDD no less than 0.5 mm to maintain the same electric
potential. The decoupling capacitor of USIM_VDD should be less than 1uF and must be placed close
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 diode array with parasitic
capacitance not exceeding 50pF. The 22
Ω 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
14
USIM1_RST
DO
1.8/ 3.0 V
Reset signal of (U)SIM1 card
13
USIM2_VDD
PO
1.8/ 3.0 V
Power source for (U)SIM2 card
19
USIM2_DATA
IO
1.8/ 3.0 V
Data signal of (U)SIM2 card
17
USIM2_CLK
DO
1.8/ 3.0 V
Clock signal of (U)SIM2 card
7
USIM2_RST
DO
1.8/ 3.0 V
Reset signal of (U)SIM2 card
