Internal Microphone; Internal Earpiece - Nokia 2608 Service Manual

RM-376
System Module and User Interface

Internal microphone

MIC1_P & MIC1_N inputs of 2608 schematic are used for the mobile terminal's internal microphone. MIC2_P &
MIC2_N input are used for headsets.
Every microphone input can have either a differential or single-ended AC connection to the QSC6020 c ircuit.
The internal microphone is differential signals. External headset microphone is single-ended.
VDD_MIC_BIAS_1.8V regulated voltage from LDO is used for microphone.
The MIC_BIAS ou tput is used for external headset to provide 1 mA of current at 1.8 +/-0.11Volts DC.
The output power for the single-ended (MICROPHONE) output is typically -22dB +/- 3 dB (0dB=1V/Pa), output
impedance is 300 ohm in 1k Hz (0dB=1V/Pa).
Figure 20 Internal microphone circuitry

Internal earpiece

EAR_P & EAR_N of QSC6 020 output pins outputs are used for the mobile terminal's internal earpiece (receiver).
The earpiece (receiver) and external louder speaker are both differential signals that come from separate
outputs at the QSC6020 are connected to different driver.
The output power for the differential earpiece output is typically 108 dB for +/- 3 dB, Impedance is 32 ohm in
1kHz.
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