• 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 USIM_DATA has been internally pulled up to 1.8V (only resistor, use an external power
source) through a 47K resistor, and no external pull-up is required.
• USIM_PRESENCE is high by default. The SIM card status can be detected by this PIN during hot
plug application. It is recommended to provide provision for pull-up.
• To avoid transient voltage overload, the USIM interface requires a 22R resistor in series with each
other on the signal line path.
• The ground of the USIM deck and the ground of the module should maintain good connectivity.
3.8 General Purpose GPIO Interface
The C16QS module contains four general purpose control signals. The interface is defined as follows:
Table 3-13 General GPIO Pin Definitions
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