Service manual

FO-IS125N
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2.5. TEL line interface block
2.5.1 Circuit description
The TEL line interface circuit is composed of the following 5 blocks.
1) Surge protection circuit (BLOCK A)
2) TEL line interface circuit (BLOCK B)
3) Handset interface circuit (BLOCK C)
4) Speaker amplifier circuit (BLOCK D)
5) Modem circuit (BLOCK E)
2.5.2 Block description
1) Surge Protection circuit (BLOCK A)
This circuit protects the circuit from the surge voltage occurring on the
telephone line.
• The AR1101 protects the circuit from the 300V or higher line surge
voltages.
• The AR1102 and AR1103 protect the circuit from the 500V or
higher vertical surge voltage.
• The VA1100 protect the Q1100, Q1101, Q1102 and Q1103 from the
330V or higher line surge voltage.
2) TEL line interface circuit (BLOCK B)
It has the following functions.
• On-hook status detection
• Dial pulse generation
• Hybrid circuit
IC1100 (CX20548-11Z) controls these functions
3) Handset interface circuit (BLOCK C)
IC1200 (CX20548-12Z) controls Telephone Speach circuit.
4) Speaker amplifier circuit (BLOCK D)
The amplifier (IC1001) of TEL line monitor and the Buzzer sound is
done.
SURGE
PROTECTION
DIODE
BRIDGE
Line Side
Device
CX20548-11Z
Digital
Isolation
Barrier
(DIB)
ACTIVE
CHOKE
TEL.LIN
HANDSET
SPEAKER OUT
Host Side Device
CX95110
Line Side
Device
CX20548-12Z
RAC
TAC
RXI
TXO
EIO
AGND_LSD
AGND_LSD
AGND_LSD
TAC
EIO
ADG
TELLINEMUTE
SPMUTE
TELMUTE
HANDSET
MIC IN
SDIB_N
SDIB_P
PDIB_N
PDIB_P
DELSIG
BZOUT
SPEAKER
Speaker
Amp
SDAA_PWM
L.P.F.
Gain
L.P.F.
Fax Engine
Controller
CX95410
CI
CIRCUIT
MODEM
BLOCK E
BLOCK A
BLOCK B
BLOCK C
BLOCK D
Fig. 6
TEL LINE MUTE: H: Handset speaker muting
L: Muting cancel
TEL MUTE: H: Handset mic muting
L: Muting cancel
SPMUTE: H: Speaker amplifier muting
L: Muting cancel