AD8113
RANK 1
128:32
1k⍀
8
8
IN 00–15
AD8113
AD8113
AD8113
AD8113
AD8113
AD8113
AD8113
AD8113
1k⍀
1k⍀
16
R
R
R
R
R
R
R
TERM
TERM
TERM
TERM
TERM
TERM
TERM
1k⍀
1k⍀
1k⍀
1k⍀
1k⍀
1k⍀
1k⍀
8
8
IN 16–31
1k⍀
1k⍀
1k⍀
16
16
16
16
8
8
IN 32–47
1k⍀
RANK 2
32:16 NONBLOCKING
(32:32 BLOCKING)
8
8
8
8
IN 48–63
8
1k⍀
OUT 00 –15
1k⍀
NONBLOCKING
1k⍀
AD8113
AD8113
8
8
8
1k⍀
IN 64–79
1k⍀
1k⍀
8
1k⍀
8
ADDITIONAL
16 OUTPUTS
(SUBJECT
8
8
IN 80–95
1k⍀
1k⍀
1k⍀
8
1k⍀
TO BLOCKING)
16
16
8
1k⍀
8
8
IN 96–111
1k⍀
8
8
IN 112–127
1k⍀
16
R
TERM
Figure 12. Nonblocking 128 × 16 Audio Array (128 × 32 Blocking)
late, and the bandwidth limitations of the devices will com-
pound. In addition, the extra devices will consume more current
and take up more board space. Once again, the overall system
design specifications will determine how to make the various
trade-offs.
When switching these differential signals, two channels are
required in the switching element to handle the two differential
signals that make up the video or audio channel. Thus, one
differential video or audio channel is assigned to a pair of
crosspoint channels, both input and output. For a single AD8113,
eight differential video or audio channels can be assigned to the
16 inputs and 16 outputs. This will effectively form an 8 × 8
differential crosspoint switch.
Multichannel Video and Audio
The good video specifications of the AD8113 make it an ideal
candidate for creating composite video crosspoint switches. These
can be made quite dense by taking advantage of the AD8113’s
high level of integration and the fact that composite video requires
only one crosspoint channel per system video channel. There are,
however, other video formats that can be routed with the AD8113,
requiring more than one crosspoint channel per video channel.
Programming such a device will require that inputs and outputs be
programmed in pairs. This information can be deduced through
inspection of the programming format of the AD8113 and the
requirements of the system.
There are other analog video formats requiring more than one
analog circuit per video channel. One two-circuit format that is
commonly being used in systems such as satellite TV, digital
cable boxes, and higher quality VCRs, is called S-video or Y/C
video. This format carries the brightness (luminance or Y)
portion of the video signal on one channel and the color (chromi-
nance, chroma, or C) on a second channel.
Some systems use twisted-pair wiring to carry video or audio sig-
nals. These systems utilize differential signals and can lower costs
because they use lower cost cables, connectors, and termination
methods. They also have the ability to lower crosstalk and reject
common-mode signals, which can be important for equipment that
operates in noisy environments, or where common-mode voltages
are present between transmitting and receiving equipment.
Since S-video also uses two separate circuits for one video channel,
creating a crosspoint system requires assigning one video channel
to two crosspoint channels as in the case of a differential video
system. Aside from the nature of the video format, other aspects
of these two systems will be the same. Stereo audio can also be
routed in a paired-channel arrangement similar to a two-channel
video system.
In such systems, the audio or video signals are differential; there
are positive and negative (or inverted) versions of the signals.
These complementary signals are transmitted onto each of the
two wires of the twisted pair, yielding a first order zero common-
mode voltage. At the receive end, the signals are differentially
received and converted back into a single-ended signal.
REV. A
–19–
ADI [ ADI ]
