UMTS/HSPA+ Module Series
UC200A-GL_Hardware_Design 39 / 78
If (U)SIM card detection function is not needed, please keep USIM_DET unconnected. A reference circuit
for (U)SIM interface with a 6-pin (U)SIM card connector is illustrated in the following figure.
Module
USIM_VDD
USIM_GND
USIM_RST
USIM_CLK
USIM_DATA
0R
0R
0R
100 nF
GND
33 pF 33 pF 33 pF
VCC
RST
CLK
IO
VPP
GND
GND
15K
USIM_VDD
(U)SIM Card Connector
Figure 20: Reference Circuit of (U)SIM Interface with a 6-pin (U)SIM Card Connector
In order to enhance the reliability and availability of the (U)SIM card in applications, please follow the
criteria below in (U)SIM circuit design.
⚫
Keep (U)SIM card connector as close as possible to the module. Keep the trace length as less than
200 mm as possible.
⚫
Keep (U)SIM card signal traces away from RF and VCC traces.
⚫
USIM_VDD maximum bypass capacitor does not exceed 1
μ
F.
⚫
Ensure the ground between the module and the (U)SIM card connector short and wide. Keep the
trace width of ground and USIM_VDD no less than 0.5 mm to maintain the same electric potential.
⚫
To avoid cross-talk between USIM_DATA and USIM_CLK, keep them away from each other and
shield them with ground surrounded.
⚫
In order to offer good ESD protection, it is recommended to add a TVS diode array whose parasitic
capacitance should not be more than 15 pF. The 0
Ω
resistors should be added in series between the
module and the (U)SIM card to facilitate debugging. The 33 pF capacitors on the USIM_DATA,
USIM_CLK and USIM_RST trances are used for filtering interference. Please note that the (U)SIM
peripheral circuit should be close to the (U)SIM card connector.
⚫
The pull-up resistor on USIM_DATA can improve anti-jamming capability of the (U)SIM card. If the
(U)SIM card traces are too long, or the interference source is relatively close, it is recommended to
add a pull-up resistor near the (U)SIM card connector.