Figure 24, Single-ended audio connection – Sierra Wireless AIRPRIME WISMO218 User Manual
Page 57
WA_DEV_W218_PTS_002
Rev 006
April 29, 2010
57
Product Technical Specification &
Customer Design Guidelines
Interfaces
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 AirPrime WISMO218 embedded module ground as close as possible to the castellation GND
pin of AirPrime 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.
Recommended ESD protection: ESDA6VIL from ST.