Panasonic KX-FM330GR Service Manual page 212

KX-FP320G / KX-FM330G
6.8. DESCRIPTION OF BLOCK DIAGRAM IN ANALOG SECTION
1. Function
The analog section is composed of the following circuits.
1 Interface circuit to connect with telephone line (NCU)
2 Analog gate array (IC5) (1) to change the circuit configuration for Tx/Rx signals of speaker phone,
Tx/Rx signals of handset, and fax signals, (2) to adjust volume of speaker, (3) to control other circuits such as NCU, and (4) to
read information sent from sensors and NCU.
Following is the detailed description of each circuit.
[NCU]: Network Control Unit
The NCU comprises of the following; DC loop forming circuit to connect with the telephone line; Switching circuit for other
interconnected telephones; Bell detection circuit; Pulse dial generation circuit; Extension line phone off-hook detection circuit;
Sidetone circuit; Remote fax activation circuit. Refer to 6.9.NCU SECTION for the details.
[Analog gate array (IC5)]
The cross-point switch installed in this IC makes it possible to change the circuit configuration for any analog signals such as
the fax signals sent from the digital MODEM board or the Tx/Rx signals for speaker phone. In addition, this analog gate array
integrates a handset circuit, signal level adjusting circuit, electronic volume, input/output ports, etc. This IC is controlled by ASIC
(IC501) on the digital board.
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