AD9883A
PIN FUNCTION DESCRIPTIONS
Pin Name
OUTPUTS
HSOUT
Function
Horizontal Sync Output
A reconstructed and phase-aligned version of the Hsync input. Both the polarity and duration of this output can be pro-
grammed 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. See the Sync Processing Block Diagram (Figure 12) to view how this pin is connected. (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.)
VSOUT
SOGOUT
SERIAL PORT (2-Wire)
SDA
Serial Port Data I/O
SCL
Serial Port Data Clock
A0
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.
DATA OUTPUTS
RED
Data Output, Red Channel
GREEN
Data Output, Green Channel
BLUE
Data Output, Blue Channel
The main data outputs. Bit 7 is the MSB. The delay from pixel sampling time to output is fixed. When the sampling time is
changed by adjusting the PHASE register, the output timing is shifted as well. The DATACK and HSOUT outputs are also
moved, so the timing relationship among the signals is maintained. For exact timing information, refer to Figures 7, 8, and 9.
DATA CLOCK OUTPUT
DATACK
Data Output Clock
This is the main clock output signal used to strobe the output data and HSOUT into external logic. It is produced by the
internal clock generator and is synchronous with the internal pixel sampling clock. When the sampling time is changed
by adjusting the PHASE register, the output timing is shifted as well. The Data, DATACK, and HSOUT outputs are all
moved, so the timing relationship among the signals is maintained.
INPUTS
R
AIN
G
AIN
B
AIN
Analog Input for Red Channel
Analog Input for Green Channel
Analog Input for Blue Channel
High impedance inputs that accept the Red, Green, and Blue channel graphics signals, respectively. (The three channels
are identical, and can be used for any colors, but colors are assigned for convenient reference.) They accommodate input
signals ranging from 0.5 V to 1.0 V full scale. Signals should be ac-coupled to these pins to support clamp operation.
Horizontal Sync Input
This input receives a logic signal that establishes the horizontal timing reference and provides the frequency reference
for pixel clock generation. The logic sense of this pin is controlled by serial register 0EH Bit 6 (Hsync Polarity). Only
the leading edge of Hsync is active; the trailing edge is ignored. When Hsync Polarity = 0, the falling edge of Hsync is used.
When Hsync Polarity = 1, the rising edge is active. The input includes a Schmitt trigger for noise immunity, with a nominal
input threshold of 1.5 V.
Vertical Sync Input
This is the input for vertical sync.
Sync-on-Green Input
This input is provided to assist with processing signals with embedded sync, typically on the Green channel. The pin is
connected to a high speed comparator with an internally generated threshold. The threshold level can be programmed in
10 mV steps to any voltage between 10 mV and 330 mV above the negative peak of the input signal. The default voltage
threshold is 150 mV. When connected to an ac-coupled graphics signal with embedded sync, it will produce a noninverting
digital output on SOGOUT. (This is usually a composite sync signal, containing both vertical and horizontal sync information
that must be separated before passing the horizontal sync signal to Hsync.) When not used, this input should be left
unconnected. For more details on this function and how it should be configured, refer to the Sync-on-Green section.
HSYNC
VSYNC
SOGIN
–8–
REV. B
AD [ ANALOG DEVICES ]
