MeiG_SLM156_Hardware Design Manual
MeiG Smart Technology Co., Ltd
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If USIM card detection function is not required, keep USIM_PRESENT pin pulling up to 1.8V. The
following figure is a reference circuit for 6-pin USIM/SIM connector:
Figure 8 Reference Circuit for 6-pin USIM/SIM Connector
In order to enhance the reliability and availability of the USIM card in your application, please follow the
criteria below in the USIM circuit design:
USIM_DATA requires a pull-
up resistor of 15kΩ to USIM_VCC; the pull-up resistor helps to
increase SIM card's anti-interference ability. When USIM card trace is too long or it is close to the
interference source, it is recommended that you add a pull-up resistor near the card;
In order to suppress stray EMI and enhance ESD protection, it is recommended to connect a
resistance of 0Ω on USIM_DATA, USIM_CLK and USIM_RESET line;
In order to improve the antistatic ability and offer good ESD protection, it is recommended to add
TVS whose parasitic capacitance should be less than 15pF on USIM_VCC, USIM_DATA,
USIM_CLK and USIM_RESET line;
In order to filter GSM900 interference, add a parallel 33pF resistance on USIM_VCC, USIM_DATA,
USIM_CLK and USIM_RESET line;
Keep layout of USIM card as close as possible to the module. Assure the length of signal wiring is
less than 200mm;
Keep USIM card signal away from RF and VBAT power line;
To avoid cross-talk between USIM_CLK and USIM_DATA, keep them away from each other and
shield them with surrounded ground;
Complete hot plugging of USIM/SIM card by using the DETECT pin of hot plug card slot and the
42pin of the module. The default setting does not support hot plug function. Contact us if you need
more information about the function.
Note:
Hot plug of SIM Connectors is not supported. Hot plug to USIM and SIM card can cause damages to
USIM /SIM card or SLM156 USIM /SIM card interfaces.
