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USIM _ VDD
USIM _ RST
USIM _ CLK
USIM _ DET
USIM _ DATA
GND
Module
Figure 19: Reference Circuit of (U)SIM Interfaces with 6-Pin (U)SIM Card Connector
To ensure the reliability and availability of the (U)SIM card in applications, follow the criteria below in the
(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 VBAT traces.
⚫
Reserve a filter capacitor for USIM_VDD, and its maximum capacitance should not exceed 1 μF.
Additionally, place the capacitor near the
⚫
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 better ESD protection, it is recommended to add a TVS component with a parasitic
capacitance not exceeding 50 pF. The 22 Ω resistors should be connected in series between the
module and the (U)SIM card to facilitate debugging. Connect 33 pF capacitors in parallel on
USIM_DATA, USIM_CLK and USIM_RST signal lines to filter RF interference. Additionally, keep the
(U)SIM peripheral circuit as close to the (U)SIM card connector as possible.
⚫
The pull-up resistor on USIM_DATA circuit 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.
SC200K_Series_Hardware_Design
R 1
22 R
R 2
R 3
22 R
22 R
R 4
C 2
C 3
C 4
33 pF
33 pF
33 pF
(U)SIM
card connector.
C 1
(U)SIM Connector
20K
1 μF
VCC
RST
CLK
D 1
ESD
Smart Module Series
GND
VPP
IO
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