Acer X203H Service Manual page 58

III. Circuit Implementations:
A.) THE MAIN BODY:
A-1.) Interface board block diagram :
(a) Circuit operations:
A basic operation theory for this interface board is to convert analog signals of Red, Green
and Blue to digital signals of Red, Green and Blue. The scaling IC has internal A/D converter,
internal OSD, built in LVDS transmitter and auto-detect input timing functions. A/D converter
is convert analog signal to digital data. OSD is offering adjustable functions to end-user.
Detect timing is for detect change mode. LVDS transmitter is used to compress the digital
RGB data, the Hsync, Vsync and pixel clock generated by Scaling then output to LCD
module. MCU stores source code and offers H/W DDC2Bi function & controls system
processing. EEPROM is stored DDC and HDCP data, OSD common data and user mode
data.
(b) IC introduction:
1.) DDC (Display Data Channel) function: We use DDC IC to support DDC2Bi function. DDC
data is store in 24C02 (EEPROM). Those data related to LCD monitor specification. PC
can read them by "SDA" and "SCL" serial communication for I²C communication for
DDC2Bi.
2.) Scalar IC: There are A/D, TMDS receiver, HDCP, Scaling, OSD and LVDS transmitter
functions built-in the RTD2545LH IC. Scaling IC is revolutionary scaling and color engine,
IN T E R FA C E B O A R D
M C U
RT D 21 20 L
E E P R O M
AT M E L
2 4C 16
D V I
1600x900
L C M
S calar
R T D 2545L H
(Su p p ort H D C P)
V G A
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D C + 3 .3 V
D C +1 .8 V
C T R L B D