LTE Standard Module Series
EC200T Series Hardware Design
EC200T_Series_Hardware_Design 42 / 90
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.
Figure 17: 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 your applications, please follow the
criteria below in (U)SIM circuit design:
Keep placement of (U)SIM card connector as close to the module as possible. Keep the trace length
less than 200 mm as far as possible.
Keep (U)SIM card signals away from RF and VBAT traces.
Assure 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. If
the ground is complete on your PCB, USIM_GND can be connected to PCB ground directly.
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 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 are used for filtering
interference of EGSM900. 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.