GE863-QUAD
1vv0300715 Rev. 1 - 19/09/06
9 SIM DESIGN GUIDES
In all Telit modules there are five pins for SIM card holder connection
These lines are:
SIMVCC | (SIM Power supply) |
SIMRST | (SIM Reset) |
SIMIO | (SIM Data) |
SIMIN | (SIM Presence/Absence) |
SIMCLK | (SIM Clock) |
SIM connection must take in account of four key issues:
9.1 Data Integrity
Standard rules for digital layout and routing must be followed taking in consideration that SIMCLK has frequency of 3.57 MHz and SIMIO has 9600Bps baud rate.
9.2 EMI/EMC
This is a key aspect to consider designing an application based on TELIT module with internal antenna and/or without a
-Antenna
-Antenna radiated field may interfere digital lines.
-Digital lines (in particular clock) may radiate spurious in the surrounding space.
To overcome all these potential problems, connection lines must be kept as short as possible and shielded.
RF bypass capacitors (10pF...33pF) closed to SIM card
When connection is not short, insertion of 10..100ohm resistor with 10..33pF capacitor (RC filter) is a good caution to improve EMI from SIMCLK line.
Do not insert resistor on SIMVCC, SIMRST and SIMIO lines, their use is not supported by SIM electrical interface.
9.3 ESD
Take standard ESD caution if application based on TELIT module has SIM holder with contacts reachable from human body.
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