⚫
VSIM is the pin to supply power for SIM card and its maximum load is 30 mA. Do not use it for
any other purpose.
⚫
Connect SIM_DATA to VSIM through an external 10 kΩ pull-up resistor since the SIM_DATA pin
is not pulled up internally.
⚫
SIM_CLK is the clock signal pin, supporting a clock frequency of 3.25 MHz.
⚫
Add ESD diodes (with a junction capacitance as low as possible) on the SIM signal lines in
applications with a high requirement of ESD protection.
⚫
Connect a resistor less than 20 Ω respectively to SIM_DATA, SIM_RST, and SIM_CLK in series
to enhance the ESD performance.
PCB Design Guidelines
⚫
SIM signals are like to be jammed by RF radiation, resulting in failure to detect the SIM card.
Place SIM far away from RF circuits.
⚫
Place SIM card close to the module and SIM traces should be as short as possible.
⚫
Place ESD protection resistors and components close to SIM card.
⚫
Surround SIM traces with ground to enhance EMC.
3.5 LIGHT
Table 3-5 LED indicator
The NET_LIGHT pin can output 4 mA and 2.8 V, therefore the LED can be directly connected to this
pin with a resistor in series. For better luminance, drive the LED with a transistor.
Figure 3-20 LED indicator
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