ViewSonic VA912-4 Service Manual page 27

Green -
Blue +
Blue -
H sync
V sync
d) Embedded OSD: Embedded 11.25K SRAM dynamically stores OSD command and fonts.
e) On chip TMDS receiver: The RTD2523 integrated TMDS receiver, which operates up to 165MHz and can
directly connect to all DVI compliant TMDS transmitters. The TMDS signals are connected to RTD2523 as
described bellow:
Pin Name
TX0+
TX0-
TX1+
TX1-
TX2+
TX2-
TXC+
TXC-
f) PWM controlling function (Pin 112, Pin 113): The RTD2523 has two dedicated PWM outputs of PWM0
and PWM1 to control audio volume and back light brightness.
g) Serial interface ports (pin 70 and pin 71): This serial interface ports communicate with MCU and support
up to 400Kbit per second transmit rate.
h) Panel interface (Pin 85~94, Pin 73~82,) : The RTD2523 driver interface is highly programmable. It
supports dual /Single LVDS interface output.
6.1.2 Power Regulator AIC1117 (U1, U3): The AIC1117 is a low dropout positive adjustable regulator with
minimum of 800mA output current capability.
So it is well suited for 3.3 V and 2.5 V Regulator.
U3 as a 2.5V regulator, Desired output voltage are determined by the equation
Volt=1.25 x (1 + R17/R15)= 2.5
U1 as a 3.3V regulator, Desired output voltage are determined by the equation
Volt=1.255 x (1+ R6/R3)= 3.3
6.2 Audio Amplifier UTC TDA7496L(U9)
The TDA7496L is a stereo 2W+2W class AB power amplifier; Features of the TDA7496L include linear volume
control, Stand-by and mute functions.
6.3 Power/Inverter Board
This is a specific power/inverter for VA912 monitor 45W 5V + 12V power and backlight which converters
12Vdc to drive four cold cathode fluorescence tubes. Electrical specification described as below.
6.3.1 Inverter Electrical specification described as below.
INPUT
ViewSonic Corporation
35
30
31
42
43
Pin NO.
20
21
18
17
15
14
23
24
Rated Input Voltage
Input Voltage Range
Input Current
Off state Input Power
12Vdc
11.4~12.6Vdc
<1.96A
<0.1W
Confidential - Do Not Copy
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VA912-4_VA912b-4