Grounding The Sim Interface; Figure 21: Connecting A Separate Ground For Sim Interface - Siemens MC45 Manual

MC45 Hardware Interface Description
P R E L I M I N A R Y

3.7.3 Grounding the SIM interface

To ground the SIM interface you can proceed from several approaches, depending on your
individual application design. The following information is just one of several options you can
apply:
Potential equalization can best be achieved by applying a separate ground for the SIM
interface. For example, the PCB of your application platform may be designed to include an
extra ground plane for the SIM card reader, rather than connecting the CCGND pin of the
board-to-board connector to the central ground on your application platform. For the SIM
card ground plane, you can choose a capacitive or inductive coupling or a zero Ohm bridge.
Often, a combination of capacitive and inductive coupling will yield best results.
It depends on your actual layout where to place these lines. For ease of planning and
designing, you can simply place the required footprints at each side of the ground plane.
This gives you the flexibility, when you test your equipment for ESD and EMC protection, to
decide which of them to use, if at all.
GSM engine

Figure 21: Connecting a separate ground for SIM interface

MC45_HD_01_V00.02a
CCGND
CCGND
GND
CCGND
Insulation
Page 56 of 90
Customer
application
GND
SIM card
reader
GND
Ground plane
Notes:
This figure is only a
simplified example
to give you an idea
where to place the
lines.
One capacitive
inductive coupling
will do, if needed at
GND
all.
12.08.2002
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