AL251 NTSC to VGA CRT/LCD Video Conversion Chip

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Averlogic's AL251 Video Scan Doubler (De-interlacer) is a video conversion chip for consumer video and multimedia applications. The AL251 converts interlaced NTSC or PAL, ITU-R BT 601 (CCIR 601) or square pixel, YUV 422 or RGB 565 digital signals into computer monitor RGB signals for direct connection to a computer monitor or progressive scan TV.

By using I 2C interface control, the AL251 can also be programmed to co-ordinate with various input resolutions, adjust screen positioning and crop video noise from around the original input video boundary. The internal RGB video lookup tables (LUT), which are controlled via the I 2C interface, can provide gamma correction for calibrating the color accuracy of different types of CRT's and improving the contrast level to display more vivid pictures. A built-in on-screen-display (OSD) with programmable bitmap RAM allows custom design icons and on-screen control panels. Overlay function is supported to create titling or on-screen-display menus for video adjustment.

The AverLogic proprietary digital signal processing technology creates a highly stable video image without tearing effects or jagged edges. The output picture is smoother and has less flicker than the original input signal/picture. This technology also keeps the gate count of the AL250 scan doubler low while outputting high quality video compared to competitors products. This will help expand the market for video applications, especially the cost sensitive ones.

AL251 Characteristics

• Convert interlaced TV signal (NTSC) into non-interlaced RGB format for CRT monitors or LCD panels
• Highly integrated design with built-in DAC, SRAM and gamma correction look-up-table
• Built-in on-screen-display with programmable bitmap
• Advanced motion adaptive digital line interpolation with no tearing or jagged edge artifacts
• Auto NTSC detect
• Digital video input of square pixel, ITU-R BT 601 (CCIR601), or user-defined format
• Analog/digital non-interlaced RGB (VGA) signal output (Scan Doubler or De-interlacer)
• I 2C programming interface
• Internal RGB video lookup tables to provide gamma correction
• Overlay support for title making and complex on-screen display
• Power-down control via I 2C
• Self-initialization without software (Plug & Play)
• 3.3 or 5 Volt support
• 80-QFP package

AL251 Applications

• TV Ready Multimedia Computer Monitor
• TV to PC Video Scan Converter Box
• Progressive Scan TV
• Video Game Station
• DVD Player
• Portable VCD Player
• LCD Monitor w/VGA Input
• Video Based Set-top Box
• RGB Projector

AL251 Functional Block Diagram

AL251 Typical Applications