User's Manual

PXS8 Hardware Interface Description
7 Sample Application
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PXS8_HD_v03.000 Page 36 of 41 2012-11-30
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7 Sample Application
Figure 10 shows a typical example of how to integrate an PXS8 module with an application.
The audio interface demonstrates the balanced connection of microphone and earpiece. This
solution is particularly well suited for internal transducers.
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 PXS8 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. If an external level controller
is required, this can be done by using for example a 5V I/O tolerant buffer/driver like a
"74AVC4T245" with OE
(Output Enable) controlled by PWR_IND.
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 [4].
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.
Disclaimer:
No warranty, either stated or implied, is provided on the sample schematic diagram shown in
Figure 10 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 PXS8 modules.