User's Manual

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Note d’étude / Technical document : URD1 – 5625.1 – 006 / 69796 Edition 03
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3.2.1.1 Notes for microphone
• Pay attention to the microphone device, It must not be sensitive to RF disturbances.
• Some microphone includes two spatial microphones inside the same shell and allow to make an
electrical difference between the environment noise (received by one of the two mic.) and the
active signal (received by the other mic. + noise) resulting in a very high SNR.
• Some resistors and capacitors should be connected as near as possible to the module as shown
in the figure.
• If you Need to have deported microphone out of the board with long wires, you should pay
attention to the EMC and ESD effect. It also the case when your design is ESD sensitive. In
those cases, add the following protections to improve your design.
• To ensure proper operation of such sensitive signals, they have to be isolated from the others by
analogue ground on mother board layout. (Refer to Layout design chapter)
Figure 15
EMC& ESD protections for microphone in case of need
3.2.1.2 Notes for speaker
• For the speaker external π filters have to be added as near as possible to the speaker to
suppress external disruption.
• Moreover, as explained for the microphone, if the speaker is deported out of the board or is
sensitive to ESD, use the schematic here after to improve the audio.
• SPKP ,SPKN, and tracks must be larger than other tracks: 0.3mm .
• As described in the layout chapter, differential signals have to be routed in parallel: it is the case
for SPKP, SPKN, MICP and MICN.
Figure 16
EMC& ESD protections for speaker in case of need