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5-4 LIU PBA
5-4-1 Summary
LIU(Line Interface Unit) circuit added only to
Msys 5200, Msys 5150, SF-5800, SF-5800P i s
controlled by the main circ u i t .
It monitors telephone line and helps interface between
the system and the telephone line. It uses
1-LIU(STI9510) to control the whole LIU,
MODEM/LINE INTERFACE, RING SIGNAL
DETECTOR, DIALER, LINE CURRENT
DETECTOR, and SERIAL INTERFACE.
5-4-2 Modem/Line Interface
T h i s i s t h e p a t h t h rough which transmitted and
r eceived data of modem is put in and out.
• CML1 Relay: It divides telephone line into
external telephone and fax.
• U3-3 TIT(Transformer Input from Transformer):
This single ended input receives image signals fro m
modem through transformer T2 and
transmits them on telephone line.
• U3-40 ROT(Receive Output Transformer): This
output transformer receives signals on telephone
line and delivers them to modem through
transformer T1. It has AC impedance of 10Kohm or
over.
• AC impedance: Normal operation range of
U3(STI9510) is from 15mA to 100mA. DC
characteristics depend on the voltage of U3-37
LI(Line Input) terminal and the voltage of
r esistance R48 between U3-37 LI(Line Input)
terminal and U3-39 LS terminal.
5-4-3 Ring Signal Detector
• U3-28(MO) terminals are ring signal output
terminals. Q4 and Q5 put out ring signals and drive
P i e z z o , b u t Msys 5200, Msys 5150, SF-5800,
SF-5800P does not use Piezzo. It has only the
functions related to ring detection such as driving
the photocoupler of U4 and delivering ring signals
to MFP
contro l l e r o f t h e m a i n .
Samsung Electronics
5 - 4 - 4 D i a l e r
5-4-4-1. MF DIAL
• Default mode it is set in DP. You can change it to
MF mode by control of MFP contro l l e r.
• MF signal can be measure d a t ( t o n e l e v e l o f l o w
g roup: typical - 14dBm) U3-4 MFO(DTMF
Generator Output). The signal is adjustable by R40,
R41 and C29. The adjusted signal enters U3-9 MFI
(DTMF Amplifier Input) and is amplified to be
transmitted on telephone line.
• U3-39 LS(Line Current Sense Input) terminals show
the final signals transmitted to telephone line.
5-4-4-2. DP DIAL
• If U3-2(DMS) is made Vcc by R42, it is set at 33:67
D P s i g n a l . I f i t i s m a d e V s s b y R 4 3 , i t i s s e t a t D P
s i g n a l . T h i s p ro d u c t i s s e t a t D P s i g n a l .
• D P signal is made by U3-27(DPn) terminals. This
signal turns on/off Q1. The signal made at that time
turns on/off Q2, which interrupts DC
c u r rent on telephone line and puts out pulse
signal on telephone line.
• U3-35 CS terminals : It makes Make Resistance by
shorting telephone line with Vss during Make
period of DP d i a l .
5-4-5 Line Current Detector
• When CML1 relay connects telephone line, U3
(STI9510) of LIU board and MFP contro l l e r o f t h e
main board (U16) start communication through
U A RT. U3 of LIU board sends signal that includes
information of line current value, whenever it
r eceives ord e r s o r d a t a f rom U16 of the main board .
Circuit Description
5-27
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