Sharp FO IS125N - B/W Laser - All-in-One Service Manual page 110

FO-IS125N
2.5. TEL line interface block
PDIB_N
PDIB_P
Digital
Isolation
Barrier
(DIB)
SDIB_N
SDIB_P
Host Side Device
MODEM
CX95110
TELLINEMUTE
TELMUTE
SDAA_PWM
DELSIG
BLOCK E
CI
BZOUT
Fax Engine
SPMUTE
Controller
CX95410
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.
BLOCK B
RAC
Line Side
Device
TAC
CX20548-11Z
DIODE
BRIDGE
RXI
EIO
TXO
AGND_LSD
TAC
Line Side
Device
CX20548-12Z
EIO
L.P.F.
Gain
L.P.F.
Fig. 6
5 – 19
BLOCK A
SURGE
PROTECTION
TEL.LIN
CIRCUIT
AGND_LSD
ACTIVE
CHOKE
AGND_LSD
HANDSET
MIC IN
HANDSET
SPEAKER OUT
ADG
BLOCK C
Speaker
Amp
SPEAKER
BLOCK D
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.
TEL LINE MUTE: H: Handset speaker muting
L: Muting cancel
TEL MUTE: H: Handset mic muting
L: Muting cancel
4) Speaker amplifier circuit (BLOCK D)
The amplifier (IC1001) of TEL line monitor and the Buzzer sound is
done.
SPMUTE: H: Speaker amplifier muting
L: Muting cancel