AD9701_15 Datasheet, PDF (5/6 Pages) Analog Devices – 250 MSPS Video Digital-to-Analog Converter

AD9701
DIE LAYOUT AND MECHANICAL INFORMATION
Die Dimensions . . . . . . . . . . . . . . . . 107 ϫ 104 ϫ 15 (± 2) mils
Pad Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Ï« 4 mils
Metalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum
Backing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . None
Substrate Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –V_S
Passivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oxynitride
Die Attach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gold Eutectic
Bond Wire . . . . . . . 1.25 mil Aluminum; Ultrasonic Bonding or
1 mil Gold; Gold Ball Bonding
APPLICATIONS INFORMATION
Raster scan video displays image data on a line by line basis,
with timing and control signals inserted between the lines. The
control signals include the horizontal synchronization pulses,
which are used to align the display circuitry at the beginning of
each line. After the complete video image is displayed on the
monitor, the process begins again with the next image. The ver-
tical reset pulse(s) that initiate this timing sequence are located
between each video image.
signals are designed to fall below the blanking level so as not to
be seen on the monitor. The actual image data is located above
the blanking level and it may be further separated from the tim-
ing signal by the setup level. The setup level is simply a buffer
zone between the timing and image data.
Generation of the timing signals for the AD9701 is controlled
by the COMPOSITE BLANKING and the COMPOSITE
SYNC inputs. In normal operation, the output level of the
AD9701 is forced to the blanking level (black) with the COM-
POSITE BLANKING control so that when the synchronization
occurs, it will not interfere (be seen) with the monitor image.
The COMPOSITE SYNC control forces the output level below
the blanking level, generating the synchronization pulse.
The “grey scale” is the image intensity range located above the
blanking level by the amount of the setup level. The setup level
is “reference black,” the darkest displayable picture intensity.
The top of the “grey scale” is “reference white” or the brightest
picture intensity. As an 8-bit device, the AD9701 divides the
“gray scale” into 256 individual levels.
Normal raster scan waveforms divide the region between the
blanking level and reference white into 100 IRE units (Interna-
tional Radio Engineers). The setup level can range from 0 to 20
IRE units but typically is around 10 IRE units, and the synchro-
nization pulse level typically falls 40 IRE units below the blank-
ing level. For the AD9701, the reference white level is 10 IRE
units below the full-scale output range (0 mA_OUT).
In terms of priority, the REFERENCE WHITE control over-
rides the data inputs, but both COMPOSITE SYNC and
COMPOSITE BLANKING override the data inputs and the
REFERENCE WHITE control. A fourth control is active at all
times, 10% BRIGHT, which adds approximately 10 IRE units
to the output level no matter what the input state of the
AD9701. The 10% BRIGHT control is primarily used to high-
light areas of the video image.
As with any high-speed device, the AD9701 requires a substan-
tial low impedance ground plane and high quality ground con-
nections to achieve the best performance. Performance can also
be improved with adequate power supply decoupling near the
supply pins of the AD9701. In ECL mode, the output of the
AD9701 is designed to drive 75 Ω cable directly, with 75 Ω ter-
minations to ground at both ends of the cable. For TTL con-
figurations, the output should be terminated to +5.0 V through
an 82 Ω resistor (see circuit below).
Raster Graphics Configuration for TTL Systems
The image data is distinguished from the timing information by
its location relative to the blanking level. The blanking reference
level is at the blackest extreme of the image data and all timing
REV. A
–5–
Standard Reconstruction Configuration