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11.17. AD9883A
11.17.1. General description
The AD9883A is a complete 8-bit, 140 MSPS monolithic analog interface optimized for capturing RGB
graphics signals from personal computers and workstations. Its 140 MSPS encode rate capability and full
power analog bandwidth of 300 MHz supports resolutions up to SXGA (1280
The AD9883A includes a 140 MHz triple ADC with internal 1.25 V reference, a PLL, and programmable
gain, offset, and clamp control. The user provides only a 3.3 V power supply, analog input, and Hsync and
COAST signals. Three-state CMOS outputs may be powered from 2.5 V to 3.3 V.
The AD9883A's on-chip PLL generates a pixel clock from the Hsync input. Pixel clock output frequencies
range from 12 MHz to 140 MHz. PLL clock jitter is 500 ps p-p typical at 140 MSPS. When the COAST
signal is presented, the PLL maintains its output frequency in the absence of Hsync. A sampling phase
adjustment is provided. Data, Hsync, and clock output phase relationships are maintained. The AD9883A
also offers full sync processing for composite sync and sync-on-green applications.
A clamp signal is generated internally or may be provided by the user through the CLAMP input pin. This
interface is fully programmable via a 2-wire serial interface.
Fabricated in an advanced CMOS process, the AD9883A is provided in a space-saving 80-lead LQFP
surface-mount plastic package and is specified over the 0C to 70C temperature range.
11.17.2. Features
• 140 MSPS Maximum Conversion Rate
• 300 MHz Analog Bandwidth
• 0.5 V to 1.0 V Analog Input Range
• 500 ps p-p PLL Clock Jitter at 110 MSPS
• 3.3 V Power Supply
• Full Sync Processing
• Sync Detect for " Plugging "
• Midscale Clamping
• Power-Down Mode
• Low Power:500 mW Typical
• 4:2:2 Output Format Mode
11.17.3. Pin Descriptions
Pin Name
OUTPUTS
HSOUT
VSOUT
SOGOUT
SERIAL PORT
(2-Wire)
SDA
SCL
A0
Function
Horizontal Sync Output
A reconstructed and phase-aligned version of the Hsync input. Both the polarity
and duration of this output can be
programmed via serial bus registers. By maintaining alignment with DATACK and
Data, data timing with respect to
horizontal sync can always be determined.
Vertical Sync Output
A reconstructed and phase-aligned version of the video Vsync. The polarity of this
output can be controlled via a
serial bus bit. The placement and duration in all modes is set by the graphics
transmitter.
Sync-On-Green Slicer Output
This pin outputs either the signal from the Sync-on-Green slicer comparator or an
unprocessed but delayed version
of the Hsync input.
(Note: Besides slicing off SOG, the output from this pin gets no other additional
processing on the AD9883A. Vsync separation is performed via the sync
separator.)
Serial Port Data I/O
Serial Port Data Clock
Serial Port Address Input 1
For a full description of the 2-wire serial register and how it works, refer to the 2-
Wire Serial Control Port section.
19
1024 at 75 Hz).
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