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

RM-57/58
Nokia Customer Care System Module
Figure 110 Internal earpiece circuitry

Internal speaker

Internal speaker is used for Internal HandsFree (IHF) call mode.
A dynamic 16mm speaker is connected to Retu ASIC's outputs HFSpP and HFSpN.
IHF amplifier integrated in Retu is a Digital Pulse Modulated Amplifier (DPMA).
Figure 111 Internal speaker circuitry

External earpiece

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.
Retu ASIC provides two output channels in either single-ended or differential format. Retu ASIC outputs XearL
and XearLC form the left channel audio output and XearR and XearRC the right channel audio output. XearLC
and XearRC are the ground pins if the output works in a single-ended operation.
On the Pop-Port side, HSEAR P and HSEAR N form the left channel output and HSEAR R P and HSEAR R N the right
channel output. Respectively, HSEAR N and HSEAR R N are the ground pins if the output works in a single-ended
operation.
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