Sierra Wireless WISMO218 Manuale Utente
WA_DEV_W218_PTS_002
Rev 005
Page 61 of 109
Product Technical Specification &
Customer Design Guidelines
Figure 24. Single-Ended Audio Connection
Caution: It is a must to avoid digital tracks crossing under and over the audio tracks.
Even when MICP is singled-ended, it is highly recommended to have the MIC ground and the LC
filter ground to act as an audio analog ground during the PCB layout. This audio ground, together
with the MICP signal, should act as the differential line pair. And this audio ground should only be
connected to the WISMO218 module ground as close as possible to the castellation GND pin of
WISMO218. It is the same case for SPKP and SPKN.
filter ground to act as an audio analog ground during the PCB layout. This audio ground, together
with the MICP signal, should act as the differential line pair. And this audio ground should only be
connected to the WISMO218 module ground as close as possible to the castellation GND pin of
WISMO218. It is the same case for SPKP and SPKN.
Also, the audio interface is ESD sensitive. It is a must to add ESD protection to the interface once it is
externally accessible.
externally accessible.
Recommended ESD protection: ESDA6VIL from ST.