External Microphone; Internal Earpiece - Nokia RM-57 Service Manual

RM-57/58
System Module Nokia Customer Care
An analogue electret microphone is connected to Retu ASIC's Mic1P and Mic1N inputs via asymmetric electrical
connection.
The microphone is biased by Retu ASIC MicB1 bias voltage output.
Figure 108 Internal microphone circuitry

External microphone

TM
Galvanic accessories are connected to the system connector (Pop-Port ).
Accessory audio mode is automatically enabled/disabled during connection/disconnection of dedicated phone
accessories.
External microphone circuitry is biased by Retu ASIC MicB2 bias voltage output. The circuitry provides a
TM
symmetrical connection for the microphone from the Pop-Port connections, XMICN and XMICP, to Retu ASIC
inputs, Mic2P and Mic2N.
Figure 109 External microphone circuitry (Pop-Port connects to the right side)

Internal earpiece

Internal earpiece is used for the HandPortable (HP) call mode. A dynamic 8mm earpiece capsule is connected
to Retu ASIC's differential output EarP and EarN.
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