System Block Diagram
Block Diagram for Main Logic Board
1.DC/DC Converter
This curcuit supplies stand-by 5V(+5Vst) and regular
5V(+5V) for using MAX785 from AC/DC adapter(+24V).
The +5V voltage supply to power swichng IC(SI4925)
and 3.3V voltage regulator.
The state of power down makes all voltage except
+5Vst down using SHDN pin from system controller
(68HC05BD1).
2. System Controller
This curcuit consists of two EEPROM IC(24C02)
which stores the control data for system and
communicates
DDC(Display Data Channel) and oscillator(X201).
The operating procedures of system controller and its
associated circuit are as follows:
1) The system controller detects frequency of vertical
sync through DFP(Digital Flat Panel) 20 pin
connector.
This controller controls the power swiching
IC(SI4925) by the detection of verticalsync(HVsync).
2) The system controller controls the brightness of
inverter by using the key control button and store
the data to EEPROM(24C02).
3. Power Swiching Circuit
This block supplies +24V(+24Vin) to the inverter for
the backlight voltage of the LCD module and +5V
(+5Vmod) for data control of the LCD module.
4. Signal Transmission
The digital video signals(R,G,B) and clock signals(CLK)
by differencial signals(Tx0,Tx1,Tx2,Txc), are transmitted
to LCD module through EMI filter from PC system which
has digital video card.
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