Audio; How The Audio Works - Nokia 3155i Troubleshooting Manual

Nokia Customer Care

Audio

How the Audio Works

The baseband supports three microphone inputs and two earpiece outputs. The
microphone inputs are MIC1, MIC2, and MIC3:
• MIC1 input is used for the moblie terminal's internal microphone
• MIC2 input is used for headsets (Pop-Port™)
• MIC3 input is used for the Universal Headset
Every microphone input can have either a differential or single-ended AC connection to
the UEMEK circuit. In the Nokia 3155/3155i/3152, the internal microphone (MIC1) and
external microphone (MIC2) for Pop-Port™ accessory detection are both differential.
However, the Universal Headset interface is single-ended. The microphone signals from
different sources are connected to separate inputs at the UEMEK. Inputs for the
microphone signals are differential types. Also, MICB1 is used for MIC1 and MICB2 is
used for MIC2 and MIC3 (Universal Headset).
IHF
Volume keys
ISSUE 1 07/2005
UHJ MIC3
Figure 7: Audio components
©2005 Nokia Corporation
3155/3155i (RM-41), 3152 (RM-61)
Baseband Description and Troubleshooting
Charging jack
Earpiece
Company Confidential
MIC
Page 11