ViewSonic VA2226w-1, Руководство по обслуживанию

Страница: 37 / 80

34
ViewSonic Corporation
Confidential - Do Not Copy
VA2226w-1
Q505 has high level DC voltage. So the gate pin of Q501 has a low level voltage, and the IC501
is normal operation. Once one of signal OP1,OP2,OP3,OP4 is low, the voltages of Q501 gate
pin is high level, and make the voltage of ISEN low level, the IC501 will be shunt down.
3. I/F Circuit
3.1 Power Supply
- +5V is converted to 3V3(U103) and 3V3 is converted to 1V8 by special circuit.
- +5V is fed to LVDS panel via Q101.
3.2 Control Signals Output
- on_BACKLIGHT signal from TSUM56AK pin20 is reversed as ON/OFF signal via Q108 to
control backlight on/off. The backlight keeps on while ON/OFF signal is low level .
- adj_BACKLIGHT signal from TSUM56AK pin21 controls backlight brightness.
3.3 VGA Input
- Red,Green,Blue input signals from CN101 #1,#2,#3 enter into TSUM56AK analog input
terminals #59,#56,#54 via C101,C102,C103 and then are processed.BAV99
( D102/D104/D106) are ESD protector to prevent IC from ESD.R101/102/103 and
R105/106/107 are matching resistance.
- Signal DDC_CLK (series clock) from CN102#15 passes through ZD104 for over voltage
protection, and then goes into EDID EEPROM IC U101 #6.
- Signal DDC_DAT (series data) from CN102#12 passes through ZD105 for over voltage
protection, and then goes into EDID EEPROM IC U101 #5.
- Signal TTL vertical sync. (Vsync) from CN102 #14 passes through ZD101 (for over voltage
protection),R115,R117 and C112 and then goes into IC TSUM56AK#64
- Signal TTL horizontal sync. (Hsync) from CN102 #13 passes through ZD103(for over
voltage protection),FB117,R114,C116,R116 and then goes into IC TSUM56AK#63.
- CN101 #5 is defined as VGA cable detect pin, this detector realize via R111,R112 and
U105 (TSUM56AK) #69, When cable plug in, DET_VGA is low level. D109 is ESD
protector.
- U101VCC is supplied by PC5V from CN101 #9 or by VCC3.3.
- U101 is an EEPROM IC,VGA EDID data is saved in it.
3.4 Scalar & MCU
- U105 (TSUM56AK) is a scalar IC with MCU.
- U105 #105~#114 and #118~#127output 8 bit LVDS digital data to panel control circuit
through CN105.
- U106 is a flash memory IC for program.
- U107 is a EEPROM IC.