Data Sheet

© 2012 Fairchild Semiconductor Corporation www.fairchildsemi.com
FMS6501A • Rev. 1.0.0 11
FMS6501A — 12x9 Video Switch Matrix with Input Clamp, Input Bias Circuitry, and Output Drivers
Layout Considerations
General layout and supply bypassing play major roles in
high-frequency performance and thermal
characteristics. Fairchild offers a demonstration board,
FMS6501ADEMO, to use as a guide for layout and to
aid in device testing and characterization. The
FMS6501ADEMO is a four-layer board with a full power
and ground plane. For optimum results, follow the steps
below as a basis for high frequency layout.
 Include 10 µF and 0.1 µF bypass capacitors.
 Place the 10 µF capacitor within 19.05 mm
(0.75 inches) of the power pin.
 Place the 0.1 µF capacitor within 2.7 mm
(0.1 inches) of the power pin.
 Connect all external ground pins as tightly as
possible, preferably with a large ground plane
under the package.
 Place channel connections to reduce mutual trace
inductance.
 Minimize all trace lengths to reduce series
inductances. If routing across a board, place device
such that longer traces are at the inputs rather than
the outputs.
If using multiple, low-impedance, DC-coupled outputs;
special layout techniques may be employed to help
dissipate heat.
If a multilayer board is used, a large ground plane
directly under the device helps reduce package case
temperature.
For dual-layer boards, an extended plane can be used.
Worst-case, additional die power due to DC loading can
be estimated at (V
CC2
/4R
L
) per output channel. This
assumes a constant DC output voltage of V
CC
/2. For 5 V
V
CC
with a dual-DC video load, add 25 / (4x75) =
83 mW, per channel.
Video Switch Matrix Applications
The increased demand for consumer multimedia
systems has created a challenge for system designers
to provide cost-effective solutions to capitalize on the
growth potential in graphics display technologies. These
applications require cost-effective video switching and
filtering solutions to deploy high-quality display
technologies rapidly and effectively to the target
audience. Areas of specific interest include HDTV,
media centers, and automotive “infotainment” (includes
navigation, in-cabin entertainment, and back-up
camera). In all cases, the advantages an integrated
video switch matrix provides are high-quality video
switching specific to the application as well as video
input clamps and on-chip low-impedance output cable
drivers with switchable gain.
Generally the largest application for a video switch is for
the front end of an HDTV, where it takes multiple inputs
and routes them to appropriate signal paths (main
picture and Picture-in-Picture (PiP)). These are normally
routed into ADCs followed by decoders. There are many
different technologies for HDTV; including LCD, plasma,
and CRT, with similar analog switching circuitry.
An example of a HDTV application is shown in Figure
14. This system combines a video switch matrix and two
three-channel switchable anti-aliasing filters. There are
two three-channel signal paths in the system; one for
the main picture, the other for PiP.
VIPDEMO™ Control Software
The FMS6501A is configured via an I
2
C-compatible
digital interface. To facilitate demonstration, Fairchild
Semiconductor had developed the VIPDEMO™ GUI-
based control software to write to the register map. This
software is included in the FMS6501ADEMO kit. A
parallel port I
2
C adapter and an interface cable to
connect to the board are also included. Besides using
the full interface, the VIPDEMO can also be used to
control single-register read and writes for I
2
C.
Figure 14. HDTV Application Using the FMS6501A Video Switch Matrix