Second, the input interface circuit analysis
Samsung LA46F71B LCD TV's input interface is more, following only the YPbPr, VGA, HDMI interface circuit for analysis.

1.YPbPr component analysis of the interface circuit of YPbPr component interface is shown in Figure 11-5.

YPbPr HD input ports and output luminance signals y D221 limiting R2037 matches, enter to the video controller IC502 (SVP-LX61), YPbPr output ports of chromatic aberration signal Pb signal D222 limiting, R2036 after the match, enter to the video controller IC502; YPbPr output ports of the color difference signals Pr D223 limiting R2035 matches, also entered into the video chip IC502.

YPbPr audio interface to the audio left and right channel audio output signals switching circuit for IC115 (MM74HC4052) switch.

2.VGA input interface circuit analysis VGA input interface circuit is shown in Figure 11-6.

①, ②, ③ foot LCD TV VGA interface receives the r, g, b signals, D328, D329, D330 limiting R343, after R344, R345, impedance matching, enter to the video controller IC502


13 feet, 14 feet by LCD TV VGA interface receives the horizontal synchronization signal (HSYNC) and field synchronization signal (VSYNC), D335, D336 after clipping, R363, R371, enter to the video controller chip IC502.

To and host communication due to LCD TV, LCD TV set for external devices required for host identification signal detection, therefore, set the DDC circuit memory IC302 (AT24C02N). DDC in memory IC302 that stores basic information about LCD TV (such as manufacturer, model number, display mode configuration, and so on), when the LCD TV when connected to the computer as a terminal display, parameter information LCD TV LCD TV VGA via I2C bus interfaces to the host computer, this information is read by the host computer, and complete identification of the LCD TV.


In addition, by the VGA audio interface for left and right channel audio signal is output via the R340, R342 to audio switching circuit for IC115 (MM74HC4052) switch.

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