MEIG SLM 320, Design Manual

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MeiG_SLM320_Hardware Design Manual
MeiG Smart Technology Co., Ltd 29/89
The reference circuit is shown in the figure below, with SIM card hot swap function.
Module
USIM_GND
USIM_VDD
USIM_RST
USIM_CLK
USIM_DET
USIM_DATA
VCC
RST
CLK
GND
VPP
IO
22R
22R
22R
GND
33PF 33PF 33PF
100nF
51K 15K
VDD_EXT USIM_VDD
USIM CARD CONNECTOR
Figure 12 Reference design drawing of the booth with hot-plug function
If user does not need USIM card hot-plug detection, keep the USIM_DET pin open. The reference circuit
is as follows:
Figure 13 Reference design drawing of the booth without hot-plugging function
For USIM card interface, in order to ensure the good performance and reliability of USIM card, the
following design principles are recommended in the circuit design:

For SIM0_DAT, SIM0_CLK and SIM0_RST lines, a 22 Ω resistance used to suppress the spurious
EMI, enhance ESD protection, and convenient debugging;

In order to improve the antistatic ability, TVS are added on USIM_VDD, USIM_DATA, USIM_CLK
and USIM_RST lines, ESD protection devices with parasitic capacitance no more than 15Pf;

33pF capacitors in parallel on USIM_VDD, USIM_DATA, USIM_CLK and USIM_RST lines are used
to filter out GSM900 interference. The peripheral devices of the USIM card shall be placed as close
as possible to the USIM booth;

USIM booth is placed close to the module to ensure that the wiring length of USIM card signal line
does not exceed 100mm;

In order to prevent USIM_CLK signals from crosstalk with USIM_DATA, the two wires should not be
too close together and an additional shielding should be added between the two wires;