ViewSonic VA2012wb-1 Service Manual page 26

d) Internal OSD: Internal SRAM allows up to 2048 characters, with programmable OSD frame size. Width is
64 columns, and Height is 32 row.
e) On chip TMDS receiver: The NT68563HF integrated TMDS receiver, which operates up to 165MHz and
can directly connect to all DVI compliant TMDS transmitters. The TMDS signals are connected to
NT68563HF as described bellow:
Pin Name
TX0+
TX0-
TX1+
TX1-
TX2+
TX2-
TXC+
TXC-
6.1.2 Mcu flash ROM
This is an 8031 CPU core embedded micro-controller, which is design for high-performance low-cost LCD
monitor control application. It contains an 8-bit 8031 micro-controller, on-chip 64 K bytes flash-type program
ROM, 1,280-bytes internal data memory, four 7-bit resolution A/D Converter, 10-channel 8-bit resolution PWM
DAC, two 16-bit timer/counters, and a UART.
a) PWM controlling function (Pin 8, Pin 9): The MCU 68F633 has two GPIO to control audio volume and
back light brightness.
b) Serial interface ports pin 25~26(DVI) and pin 27~28(VGA): This serial interface ports communicate with
MCU and support up to 400Kbit per second transmit rate.
6.1.2 Power Regulator AIC1563 (U1), AIC1117 (U3, U4, U5): The AIC1563 is a monolithic control IC
containing the primary functions required for DC-to-DC converters. The device consists of an internal
temperature compensated reference, comparator, controlled duty cycle.
Oscillator with an active current sense circuit, desired output voltage are determined by the equation,
Volt = 1.25 *(1 + R121 / R122), in this case, the output voltage are 5 Volts
AIC1117 (U3, U4, U5): 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.
U5 as a 1.8V regulator, desired output voltage are determined by the equation
Volt=1.25 x (1 + R90/R88) = 1.8
U3 as a 3.3V regulator, desired output voltage are determined by the equation
Volt=1.255 x (1+ R86/R85) = 3.3
U4 as a 3.3V regulator, desired output voltage are determined by the equation
Volt=1.255 x (1+ R89/R87) = 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 Inverter Board
This is a specific inverter for VA2012 monitor 40W backlight which converters 20Vdc to drive 6 tubes cold
cathode fluorescent tubes. Electrical specification described as below.
ViewSonic Corporation
Pin NO.
9
8
6
5
3
2
11
12
23
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