AG Neovo AIC U-17, Service Manual

Page: 19 / 59

AG Neovo U-17 service manual
Page of 59 19
4. THEORY OF OPERATION
This section describes the function of the LCD monitor per functional block.
L7AM-A1 monitor includes main Board (including audio and earphone board inside), power board and button board and USB board
4.1 Main BOARD
The main board is a two-layers, single-landed design with ground and ground planes provided. The VGA and DVI cable are the cables that contain
video signal, sync signal and DDC signal from PC VGA and DVI adapter This system board consists of 3 functional areas : flat panel controller,
Micro controller and APA2069JI-TUL audio controller
4.1.1 Flat panel controller… RTD2525LH
(U7)
The heart of the system board is
RTD2525LH
. The
RTD2525LH
is a graphics processing IC for LCD monitor. It provides some control functions
required for LCD panel. On-chip functions include a high-speed triple-ADC , PLL, high scaling engine and OSD controller.
a) Clock Generation :
Crystal Input Clock (XIN and XOUT). This is the input pair to an internal crystal oscillator and corresponding logic. 24 MHz crystal are
recommended.
b) Hardware Reset ( Pin 4 )
Hardware Reset signal is generated by Pin 4.It assert a reset signal at east 1 ms.
c) Analog to Digital Converter
The
RTD 2525LH
chip has three ADC's (analog-to-digital converters), one for each color (red, green and blue) . The analog RGB signals are
connected to
RTD2525LH
as described below