User's Manual

page 15/51
HiAll
NC
User Manual 2012/06/28
Figure 6: Filter and ESD protection of microphone
3.3.1.1.2 Notes for speaker
As explained for the microphone, if the speaker is deported out of the board or is sensitive to ESD, use the
schematic here to improve the audio.
Figure 7: Filter and ESD protection of 32 ohms speaker

HSET_OUT_P, HSET_OUT_N tracks must be larger than other tracks: 0.1mm.

As described in the layout chapter, differential pairs must be routed in parallel and same length
(HSET_OUT_P and HSET_OUT_N signals)

The impedance of audio chain (filter + speaker) must be lower than 32Ω.

To use an external audio amplifier connected to a loud-speaker, use serial capacitors of 10nF on HiAll
NC
audio outputs to connect the audio amplifier.
MIC
33pF
33pF
Ferrite Bead
Ferrite Bead
+
ESD protection
ESD protection
HiAll
NC
HiAll
NC
HSET_OUT_P
HSET_OUT_N
speaker
Ferrite Bead
Ferrite Bead
18pF
18pF
ESD protection
ESD protection