Circuit Description - ViewSonic VE510s-4 Service Manual

4. Circuit Description (VE510s-4/VE510b-4)
A. AC-DC CONVERTER
The power supply with a high-integrated green-mode PWM controller provides several
features to enhance the performance of power flyback converters.
I801 is a PWM controller and provides many protection functions.
I802 is a photo couple to transfer the feedback signal from the second side which I803
detected both of the output DC voltage on 3.3V and 12V.
D813 detected the working voltage on I801 and Q805 would pull down the voltage on I801
pin5 to shut down I801 if feedback loop was failed.
R826 would be a dynamic load which was active while backlight was turned off and system
still working on, this kept 12V output voltage under 13V to protect the panel.
went to power saving mode, the R826 would no loaded. This was detected by I804 and Q803
active the R826 to load or not.
B. Scaling controller
The RTD2013 ADC is to convert RGB analog signal to digital signal that scaling chip can
acknowledge.
The HSYNC input receives a logic signal and provides the frequency reference for pixel clock
generation.
The scaling IC is to converts the input signal ranging from VGA to XGA into XGA resolution
that panel can acknowledge.
General
PIN DESCRIPTION
(I/O Legend: A= Analog , I=Input ,O=Output ,P=Power ,G=Ground)
■ ADC: 15 pins
ADC_ GND
ADC_REFIO
ADC_VDD
BLUE+
BLUE-
ADC_ GND
SOG/ADC_TEST
GREEN+
GREEN-
ADCB_VDD
RED+
RED_
ADC_GND
ADC_GND
ViewSonic Corporation
Embedded dual DDC support DDC1, DDC2B,DDC/CI
  
Zoom scaling up and down
  
Embedded Pattern Generator
  
No external memory required.
  
Require only one crystal to generate all timing
  
Embedded reset control output
  
   Embedded crystal output to MICROP
3 channels 8 bits PWM output, and selectable PWM clock frequency.
  
Name I/O Pin No
AG
AP
AP
AI
AI
AG
AIO
AI
AI
AP
AI
AI
AG
AG
Description
27 ADC ground
28 ADC band-gap voltage de-coupling 1.20V
29 Analog power
30 Analog input from BLUE channel
31 Analog input ground from BLUE
channel
32 ADC ground
33 SOG in/ADC test pin
34 Analog input from GREEN channel
35 Analog input ground from GREEN
channel
36 Analog power
37 Analog input from RED channel
38 Analog input ground from RED
channel
39 Analog ground
40 Analog ground
Confidential - Do Not Copy
15
After system
Note
(3.3V)
(3.3V)
VE510s-4_VE510b-4