ViewSonic VP2030b-1 Service Manual page 26

6. THEORY OF OPERATION
This section describes the function of the LCD monitor per functional block.
This monitor includes MB board, power board and button board and USB board
6.1 MB BOARD
The MB board is a Four-layer, single -landed design with ground and internal planes provided. DC power from the
power board enters the board through a 8P connector. The other connector on the board is for the button board. The
VGA cable is a signal cable that carries the video, sync and DDC signals from the PC VGA adapter. This system
board consists of 4 functional areas: flat panel controller, MCU with flash ROM, and power regulators
USB function.
6.1.1 Flat panel controller... Gm1601(U21)
The heart of the system board is the Realtek Gm1601. The Gm1601 is a graphics processing IC designed for
LCD monitors. It provides all key IC functions required for LCD displays. On-chip functions include a
high-speed triple -ADC, PLL, high scaling engine and OSD controller.
a) Clock Generation :
Crystal Input Clock (TCLK and XTAL). This is the input pair to an internal crystal oscillator and
corresponding logic. A 14.318 MHz crystal is recommended.
b) Analog to Digital Converter:
The Gm1601 chip has three ADC's (analog-to-digital converters), one for each color (red, green and
blue) .The analog RGB signals are connected to Gm1601 as described
c) SST 39VF040 Micro Controller: The SST 39VF040 micro controller (MCU) serves as the system micro
controller. It programs the Gm1601 and manages other devices in the system such as the keypad
Viewsonic Corporation
Pin Name
Red +
Red -
Green +
Green -
Blue +
Blue -
Pin number Pin Number Usage
AE24 Key / Power on ,off
P3 NV_RAM (U4) SDA
P4 NV_RAM (U4) SCL
AF24 Key_down
AF26 Key_right
AF25 Key_up
AE25 Key_left
AD24 Key_select
D25 LED_red
D26 LED_green
Pin Number
D2
D1
C2
C1
B2
B1
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VP2030b-1