User Guide

CCS Technical Documentation System Module and User Interface
Company confidential NPL-3
Issue 1 3/03 ãNokia Corporation. Page 33
Internal Audio
IHF Speaker & Stereo Audio Amplifier
Integrated Hands Free Speaker, 16mm MALT, is used to generate speech audio, alerting
and warning tones in NPL-3. Audio amplifier is controlled by the UPP. Speaker capsule is
mounted in the C-cover. Spring contacts are used to connect the IHF Speaker contacts to
the main PWB.
Figure 11: IHF speaker and amplifier
Internal Microphone
The internal microphone capsule is mounted to in the UI-frame. Microphone is omni
directional and it’s connected to the UEM microphone input MIC1P/N. The microphone
input is asymmetric and the UEM (MICB1) provides bias voltage. The microphone input
on the UEM is ESD protected. Spring contacts are used to connect the microphone to the
main PWB.
Figure 12: Internal microphone
Internal Speaker
The internal earpiece is a dynamic earpiece with impedance of 32 ohms. The earpiece
must be low impedance one since the sound pressure is to be generated using current
and not voltage as the supply voltage is restricted to 2.7V. The earpiece is driven directly