THS8083A Datasheet, PDF (7/64 Pages) Texas Instruments – TRIPLE 8 BIT 80 MSPS 3.3V VIDEO AND GRAPHICS

1 Introduction
The THS8083A is a complete solution for digitizing video and graphic signals in RGB or YUV/YCbCr color spaces.
The device supports pixel rates up to 80 MHz. Therefore, it can be used for PC graphics digitizing up to the VESA
standard of XGA (1024 X 768) resolution at 75 Hz screen refresh rate, and in video environments for the digitizing
of digital TV formats, including HDTV.
The THS8083A is powered from a single 3.3-V supply and integrates a triple high-performance A/D converter with
clamping functions and variable gain, independently programmable for each channel. The clamp timing window is
provided by an external pulse or can be generated internally. The programmable gain amplifiers consist of coarse
and fine gain control blocks. The THS8083A includes slicing circuitry on the Y or G input to support sync-on-green
or sync-on-luminance extraction.
The THS8083A also contains a completely digital PLL block consisting of phase-frequency detector (PFD), discrete
time oscillator (DTO), and programmable divider to generate the (sampling) clock from the incoming horizontal sync
(HS) signal, depending on the incoming video resolution. Any pixel rate can be generated in the 13–80 MHz range.
Moreover, the output phase of the synthesized clock can be controlled with subpixel accuracy (31 uniform settings).
Programmable time constants allow changing the PLL loop bandwidth by the integrated PLL loop filter. Alternatively,
the user may bypass the PLL when an external pixel clock is available. Even then the DTO synthesized clock is still
available externally and can therefore be used in other parts of the (graphics) system. Extensive PLL and input
monitoring functions are integrated for typical functionality required in LCD/DMD monitor/projection systems (input
format detection, autocalibration).
All programming of the part is done via an industry-standard normal/fast I²C interface, which supports both reading
and writing of register settings. The THS8083A is available in a space-saving TQFP 100-pin PowerPAD package.
1.1 Features
The THS8083A supports the following features:
• Analog Channels – Three digitizing channels, each with independently controllable clamp, PGA, and ADC
– Clamp: 256-step programmable RGB or YUV clamping during external or internal clamp timing window
– PGA: 6-bit coarse/5-bit fine programmable gain amplifier
– ADC: 8 bit 80 MSPS A/D converter
– Composite sync: Integrated sync-on-green/sync-on-luminance extraction from green/luminance
channel or from dedicated input
– Support for dc and ac-coupled input signals
• PLL
– Fully integrated digital PLL (including loop filter) for pixel clock generation
– 13-80 MHz pixel clock generation from reference input
– Adjustable PLL loop bandwidth for minimum jitter or fast acquisition/wide capture range modes
– 5-bit programmable subpixel accurate positioning of sampling phase
– Noise gates on HS and VS inputs to avoid false PLL updating
PowerPAD is a trademark of Texas Instruments.
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