Circuit Description - ViewSonic N2230w-2M Service Manual

4. Circuit Description

A/D converter
This brick convert is the 110-220AC input voltage to 12V output for inverter use and 5V for panel ,
system and audio use and 3.3V,1.2V for controller use.
INVERTER
In order to drive the CCFLs embedded in the panel module, there is a half bridge inverter to convert by
the controller.
The input 12V up to hundreds of AC voltage output.
The inverter is formed by symmetric in order to drive the separate lamp modules.
The input stage consists of a PWM controller, half bridge inverter, and switching MOSFET to convert
DC input into AC output.
The output stage consists of a tuning capacitor, coupling capacitor, transformer, push-pull MOSFET
pair to boost AC output up to hundreds of voltage.
And one resister is serial to lamp for output voltage feedback.
There are two signal to control the inverter which come from system.
Logic "high" level which send to I901 is turn on the inverter.
BRI signal control brightness by DC level which was integral from PWM signal.
I206 Scaler MSD2232L
The MSD2232L is a highly integrated SOC for LCD/PDP DTV applications with resolutions up to
SXGA/WXGA+.
It is configured with an integrated triple-ADC/PLL,a multi-standard TV video and audio decoder, a
DTV video and audio decoder, a video de-interlacer, a scaling engine, the MStarACE-3 color engine, a
graphics engine, an 8-bit MCU and a built-in output panel interface.The built-in DTV decoder
including transport streamde-multiplexer and MPEG-2 AV decoder are designed to support ATSC
HD/SDTV program while handling ATSC CC and EPG. For analog TV,the MSD1226L receives
NTSC/PAL/SECAM CVBS/S-Video and component video signals from various analog graphic &
video sources.To further reduce system costs, the MSD1226L also integrates intelligent power
management control capability for green-mode requirements and spread-spectrum support for EMI
management.
Analog Interface
VCLAMP CVBS/YC Mode Clamp Voltage Bypass 20
REFM Internal ADC Bottom De-coupling Pin 18
REFP Internal ADC Top De-coupling Pin 19
SOGIN1 Analog Input Sync-on-Green slicer input from channel 1 2
BINP Analog Input Analog B Input of VGA 1
GINP Analog Input Analog G Input of VGA 3
RINP Analog Input Analog R Input of VGA 4
PBINP Analog Input Analog Pb Input 11
VCOMB Analog Input Common Negative Input for B-component ADC 12
SOGIN0 Analog Input Sync-on-Green slicer input from channel 0 13
VCOMG Analog Input Common Negative Input for G-component ADC 15
YINP Analog Input Analog Y Input 14
VCOMR Analog Input Common Negative Input for R-component ADC 17
PRINP Analog Input Analog Pr Input 16
C0INP Analog Input Analog Chroma Input for TV S-Video0 23
YS0INP Analog Input Analog Luma Input of TV S-Video0 24
C1INP Analog Input Analog Chroma Input for TV S-Video1 /
Analog Composite Input of TV CVBS4
25
YS1INP Analog Input Analog Luma Input of TV S-Video0 /
Analog Composite Input of TV CVBS3
26
VCOMY Analog Input Common Negative Input for Y-component ADC 27
CVBSOUT Analog Output CVBS Output buffered from CVBS input 32
CVBS0 Analog Input Analog Composite Input for TV CVBS0 31
CVBS1 Analog Input Analog Composite Input for TV CVBS1 30
CVBS2 Analog Input Analog Composite Input for TV CVBS2 29
CVBS3 Analog Input Analog Composite Input for TV CVBS3 28
DREXT Analog Input Reference Current Generator, 820 ohm to Ground 170
ViewSonic Corporation
25
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N2230w-2M