LPM2100 mg NB Module Hardware User Guide
Shanghai Yuge Information Technology Co., Ltd.
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Figure 3-16 SIM circuit design
①
It is recommended to select ONSEMI's SMF15C device for ESD protection on the
SIM card interface line. The peripheral circuit device should be placed close to the card holder.
The SIM card holder is close to the module layout.
②
The SIM card circuit is susceptible to radio frequency interference and does not
recognize or remove the card. Therefore, the card slot should be placed as far as possible from
the RF radiation of the antenna. The trace should be as far away as possible from the RF,
power supply and high-speed signal lines.
③
The SIM_DECT has been internally pulled up to VDD_EXT with a 100K resistor
and no external pull-up is required.
④
SIM_DECT is the SIM card inserted or not inserted detection pin, the default is high
level, the SIM card status can be detected by this PIN pin during hot plug application.
⑤
To avoid transient voltage overload, the SIM interface requires a 22R resistor in
series with each other on the signal line path.
⑥
The ground of the SIM card holder and the ground of the module should maintain
good connectivity.
3.7.2 SIM_DECT Hot swap reference design *
The LPM2100 mg series modules support SIM hot plugging.
The SIM_DECT pin acts as an input detection pin to determine whether the SIM card is
inserted or not. The SIM_DECT pin defaults to a high level. The hot plug function can be
turned on or off by AT+HOSCFG. This function is disabled by default (see the
“
RDA_AT
Command Manual
”
provided in the domain for details).
