Wavecom GR64 Application Note - page 9
2.2.1 SIMVCC
The SIMVCC-signal has a built-in 470nF capacitor inside the Wireless CPU. This
capacitance might not be enough, and it might not add the capacitance where it is
really needed. Provision for a capacitor (C
VCC
) ranging between 1uF to 10uF or more
should be made available as close to the SIM-holder as possible. This will enable
easier type approval passing of the VCC and IO test cases (27.17.2.1).
Provide the capability of adding capacitance on SIMVCC as close to
the SIM-holder as possible. The pad layout should support capacitors
up to 10uF.
TIP
2.2.2 SIMCLK
The SIMCLK-line is a CMOS driver from the Wireless CPU to the application. In case
the application adds inductance in the trace from SIMCLK of the system connector to
C3 of the SIM-holder, the application might experience over and/or under shoot
problems when running test cases (27.17.2.3). This can be taken care of by adding a
series resistance as close to the system connector as possible. The resistor should be
in the 10 ohm to 100 ohm range, but the required value might differ depending on
the application implementation.
Provide the capability of adding an extra series resistor 10ohm to
100ohm close to the system connector to overcome possible over
and/or under shoot problems.
TIP
GR/GS64 Application Note
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SIM Interface
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