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Circuit Description
5-8 LIU PBA
The LIU (Line Interface Unit) PBA performs a function of modem AFE interface, line signal in/output, off-
hook detect, ring signal detect, MF/DP dialing, TAD interface, and telephone circuit. It also contains
protection circuit to avoid damage from lightning or line. The function diagram is provided below.
AC coupliy
Capacitor
TIP
RING
EXT
LINE
RINGER
5-8-1 Modem AFE and Interface
TIT (Transformer Input from Transformer) : The signal is applied to LIU input of the modem.
ROT (Receive Output to Transformer) : The signal from line is applied to modem.
40
ROT
3
TIT
5-4
HOOK off 2
RING DET
Figure 5-4 LIU Function Diagram
Remote
Figure 5-5 Modem AFE and Interface
MIC
RCV
Rx-SIG
Tx-SIG
vcc
UART-Rx
vcc
UART-Tx
NPO
Key input
X-tal
Modem
Bell
Samsung Electronics
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