Nokia 300 Service Manual page 121

RM-781
System Module
Figure 19 Audio interface
Internal microphone
The internal microphone is used for HandPortable (HP) and Internal HandsFree (IHF) call modes. The data
and CLK line of the digital microphone are connected to RAPU and the operating voltage of 1.8V is supplied
by the EM ASIC.
Internal earpiece
The internal earpiece is connected to EM-ASIC EARP and EARN lines.
External earpiece and microphone
The AV headset earpiece is connected to EM ASICs XEARl, XEARLC, XEARR and XEARRC.
The AV headset microphone line is connected to EM ASICs Mic2 line.
AV connector
The AV connector handles audio signal output. It has audio left and right signals separately (pin 4 and 5) and
the microphone signal wired to pin 3.
The plug detection signal handles the AV connector plug detection with HeadDet signal from EM ASIC.
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