Product Info

NB-IoT Module Series
BC660K-GL Hardware Design
BC660K-GL_Hardware_Design
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A reference circuit design for (U)SIM interface with a 6-pin (U)SIM card connector is illustrated below.
Figure 16: Reference Circuit for (U)SIM Interface with a 6-pin (U)SIM Card Connector
To enhance the reliability and availability of the (U)SIM card in applications, follow the criteria below in
(U)SIM circuit design:

Keep the placement of (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.

Assure the trace between the ground of the module and that of (U)SIM card connector is short and
wide. Keep the trace width of the ground no less than 0.5 mm to maintain the same electric potential.
The decoupling capacitor between (U)SIM_VDD and GND should be not more than 1 μF and be
placed close to the (U)SIM card connector.

To avoid cross-talk between (U)SIM_DATA and (U)SIM_CLK, keep them away from each other and
shield them separately with the surrounded ground.

In order to offer good ESD protection, it is recommended to add a TVS diode array whose parasitic
capacitance should be not more than 50 pF. The ESD protection device should be placed as close to
(U)SIM card connector as possible, and ensure the (U)SIM card signal lines go through the ESD
protection device first from (U)SIM card connector and then to the module. The 22 Ω resistors should
be connected in series between the module and the (U)SIM card connector to suppress EMI spurious
transmission and enhance ESD protection. Please note that the (U)SIM peripheral circuit should be
(U)SIM_CLK
13
(U)SIM card clock
(U)SIM_DATA
11
(U)SIM card data
(U)SIM_RST
12
(U)SIM card reset
(U)SIM_GND
10
Specified ground for (U)SIM card