Samsung MSYS 5150, Руководство по обслуживанию

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5-28 Samsung Electronics
Circuit Description
5-4-6 Serial Interface
• This part does serial communication with MFP
controller of the main board (MAIN PBA:U16) that
controls the whole system. It controls LIU by giving
and taking all control orders and line
status.
• U3-11 RxD : Schmitt Trigger input, Receiving
terminal.
• U3-29 TxD : Open Drain output terminal
• Standard UART communication
- Baud Rate : 9600bps
- Start, Stop bit : 1bit each
- Data bits : 8 bit
- Parity bit : none
5-4-7 MAJOR FUNCTIONS OF PARTS
1) U3 : STI9510
- Key part of LIU board. Speech Network,
Dialer, Ringer and UART are built in one IC
package.
2) U5 : PC817
- Photo coupler. It enables UART of
U3(STI9510) to receive control signal or
dialing information from MFP controller of
the main board (U15).
- Insulation Detween prinary and secondany
circuit part.
3) U6 : PC817
- Photo coupler. It enables UART(U3-29:TxD)
of U3(STI9510) to deliver telephone line
status or response signal about control
signal or dialing information from LIU MFP
controller of the main board (U15).
- Insulation Detween prinary and secondany
circuit part.
4) U4 : PC817
- It senses and delivers ring signal to the main
board.
- Insulation Detween prinary and secondany
circuit part.
5) U2 : PC814
- It senses hook-off (Line connection) of the
external telephone and delivers it to the main
board.
- Insulation Detween prinary and secondany
circuit part.
6) BD1 : BRIDGE DIODE
- Regardless of the polarity of DC power
f rom telephone line, the voltage put out on
Pin.1 has polarity against pin
Pin.2. So DC loop forms always in the same
direction regardless of the polarity of the
telephone line.
7) T2,T3 : T R A N S F O R M E R
- It delivers signals from the telephone line
to modem or signals from modem to the
telephone
line.
- Insulation Detween prinary and
secondany circuit part.