CLM920_NC3_LTE Module Hardware User Guide
Shang Hai YUGE Information Technology co., LTD
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Figure 3-13 USIM design circuit diagram
The USIM interface cable is recommended to use ONSEMI's SMF15C device for ESD protection. The
peripheral circuit components should be placed close to the card holder. The SIM card holder is close
to the module layout.
The USIM card circuit is susceptible to radio frequency interference and does not recognize or drop
the card. Therefore, the card slot should be placed as far as possible from the RF radiation of the
antenna. The card trace should be as far away as possible from the RF, power supply and high-speed
signal lines.
The UIM_DATA has been internally pulled up to VDD_EXT through a 47K resistor, and no external
pull-up is required.
UIM_DET is the USIM card insertion or non-insertion detection pin. It is high by default. The SIM card
status can be detected by this PIN pin during hot plug application.
To avoid transient voltage overload, the USIM interface requires a 22R resistor in series with each
other on the signal line path.
3.7.2 USIM_DET Hot Swap Reference Design
The CLM920_NC5 Mini PCIE module supports SIM hot plugging.
The USIM_DET pin acts as an input detection pin to determine whether the SIM card is inserted or
not. The UIM_DET pin defaults to a pull-up high.
Table 3-10 SIM card hot swap detection pin definition
NO
UIM_DET status
Functional description
1
High
SIM card insertion, UIM_DET is high
2
Low
SIM card is pulled out, UIM_DET is low
Figure 3-14 SIM card hot plug detection
It is recommended to add a diode protection next to the UIM _DET pin of the module.