Analog Circuit - Panasonic KX-T7665NE Service Manual

10.8. ANALOG CIRCUIT

This circuit performs the setting of the call path/vol. adjustment in each call mode by IC4.
The audio gain of each call is determined by download data from PBX.
- IC2 sends each audio data to IC3 by PCM interface.
- IC2 receives each audio data from IC3 by PCM interface.
1. Handset Call
Transmitting signal is inputted from handset microphone and
amplified by IC4 built-in Amp
adjustment by IC4
sent to PBX.
Receiving signal is inputted from PBX
conversion after the input to IC4 in PCM data
by DSP of IC4
2. Speakerphone Call
The speakerphone mode can only provide a one-way
communication path.
IC3 compares transmitting signal and receiving signal during
speakerphone mode, then provide a one-way communication path.
Transmitting signal is inputted from SP phone mic. and amplified
by IC4 built-in Amp
inputted to IC3 and IC2 in PCM data
Pin 26 of IC4
A/D conversion
A/D conversion
IC2
outputted from Q51 to handset.
inputted to IC3 in PCM
20
Gain
then
IC3 D/A
Gain adjustment