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5-4
Samsung Electronics
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.
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.
Figure 5-4 LIU Function Diagram
Figure 5-5 Modem AFE and Interface
AC coupliy
Capacitor
TIP
RING
HOOK off 2
EXT
LINE
RINGER
RING DET
X-tal
NPO
Key input
RCV
Rx-SIG
Tx-SIG
UART-Rx
vcc
vcc
UART-Tx
MIC
ROT
Remote
Bell
Modem
TIT
40
3
Circuit Description