Audio Concept - Nokia 5130 Service Manual

RM-495; RM-496
System Module

Audio concept

This phone has a conventional solution on earpiece and vibra. Both are handled by AVILMA N2200. Two
integrated handsfree speakers are driven by an additional amplifier also handled by AVILMA. The microphone
has a digital interface and its RF-filtered lines are directly connected to RAP D2800 for processing.
Since this phone has focus on audio playback, it contains improved circuits for audio handling. The STDAC is
a D/A-converter that offers better signal to noise ratio than conventional circuits. This improves the playback
audio quality significantly. The playback audio (e.g. music stored in the phone or on the micro USB) is
processed from RAP D2800 via STDAC and an amplifier to the AV-connector (for e.g. headset). The STDAC
contains a FIFO memory that can store up to 85ms of playback time (allowing D2800 to go to sleep mode
and save energy). The entire audio playback circuits are optimized to save energy and improve audio quality
and the energy saving is quite significant (more than 50%, which means longer playback time than in a
conventional design).
Figure 28 Audio block diagram
The Plug detector (PLUG_DET) in the AV connector enables the external microphone, when the phone function
is used. The headset earphones will still be processed via STDAC (without using the power saving mode). The
audio quality will to some extent be improved (saying other links in the audio chain doesn't have the same
high quality as the playback channel has).
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