Cinterion BGS3, Hardware Interface Description

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BGS3 Hardware Interface Description
7 Sample Application
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BGS3_HD_v01.000d Page 103 of 109 2010-03-26
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7 Sample Application
Figure 46 shows a typical example of how to integrate a BGS3 module into the GSM part of a
mobile application. Usage of the various host interfaces depends on the desired features of the
application.
Audio interface 1 demonstrates the balanced connection of microphone and earpiece. This so-
lution is particularly well suited for internal transducers. Audio interface 2 uses an unbalanced
microphone and earpiece connection typically found in headset applications.
The charging circuit is optimized for the charging stages (trickle charging and software con-
trolled charging) as well as the battery and charger specifications described in
Section 3.5 .
The PWR_IND line is an open collector that needs an external pull-up resistor which connects
to the voltage supply VCC µC of the microcontroller. Low state of the open collector pulls the
PWR_IND signal low and indicates that the BGS3 module is active, high level notifies the Pow-
er-down mode.
If the module is in Power-down mode avoid current flowing from any other source into the mod-
ule circuit, for example reverse current from high state external control lines. Therefore, the
controlling application must be designed to prevent reverse flow.
While developing SMT applications it is strongly recommended to provide test points
for certain signals resp. lines to and from the module - for debug and/or test purposes.
The SMT application should allow for an easy access to these signals. For details on
how to implement test points see
[9] .
The EMC measures are best practice recommendations. In fact, an adequate EMC strategy for
an individual application is very much determined by the overall layout and, especially, the po-
sition of components. For example, mounting the internal acoustic transducers directly on the
PCB eliminates the need to use the ferrite beads shown in the sample schematic. However,
when connecting cables to the module’s interfaces it is strongly recommended to add appro-
priate ferrite beads for reducing RF radiation.
Disclaimer
No warranty, either stated or implied, is provided on the sample schematic diagram shown in
Figure 46 and the information detailed in this section. As functionality and compliance with na-
tional regulations depend to a great amount on the used electronic components and the indi-
vidual application layout manufacturers are required to ensure adequate design and operating
safeguards for their products using BGS3 modules.