MAX7428/MAX7430/MAX7432A
Standard Definition Video Reconstruction
Filters and Buffers
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When processing composite video set the clamp level to
+1V (CLEVEL = 0). Use the MAX7430 to process two
synchronous composite signals simultaneously. Use the
MAX7432A to process three synchronous composite
signals simultaneously.
Y/C Video Filtering
The MAX7430 is ideally suited for processing S-Video (Y/C)
signals (Figure 10). Ensure that IN1_ filters the signal that
contains the sync information (Y) since the clamping on
IN2_ is internally controlled by the master channel (IN1_)
sync. Set the clamp level for IN1_ to +1V (CLEVEL1 = 0)
and set the clamp level for IN2_ to +1.5V (CLEVEL2 = 1).
Use two MAX7428s for Y/C video filtering. Since only the
Y signal contains the sync, a typical Y/C video-filtering
application requires a master-slave configuration of the
SYNCIO. The MAX7428 processing the Y signal should
have SYNCIO configured as an output, which in turn dri-
ves the SYNCIO of the second MAX7428, processing the
C signal that has its SYNCIO configured as an input
(Figure 11). Clamping level for the Y signal should be set
for +1V (CLEVEL = 0), and clamping level for the C sig-
nal should be set for +1.5V (CLEVEL = 1). Use the
MAX7432A to filter one Y/C and one composite video
signal that are synchronous.
Component Video (RGB
or Y P
b
P
r
) Filtering
Component video consists of three separate signals.
Typically the three signals are separate red, green, and
blue (RGB) signals or Y (luma) and two color difference
signals: B-Y (P
b
) which is blue minus luma and R-Y (P
r
),
which is red minus luma. Sync information is included
with the Y signal of Y P
b
P
r
component video, or in the
case of RGB, sync is usually carried on the G or on a
separate H sync line. The MAX7432A is ideally suited
for filtering component video signals. Ensure that the
sync signal (Y for Y P
b
P
r
signals and usually G for RGB
signals) is filtered by IN1_ since IN2_ and IN3_ are
internally synced to IN1_. Set the clamp level for IN1_
to +1V (CLEVEL1 = 0) and set the clamp levels for IN2_
and IN3_ to +1.5V (CLEVEL2, 3 = 1) for Y P
b
P
r
filtering
(Figure 12) and set all clamp levels to 1V (CLEVEL_ =
0) for RGB filtering (Figure 13). A Y P
b
P
r
component
video-filter application requires three MAX7428s with
SYNCIO master-slave configuration. The MAX7428 pro-
cessing the Y signal has its SYNCIO configured as an
output, which in turn drives the SYNCIO inputs of the
other MAX7428s (Figure 14). For RGB video signal fil-
tering with a separate horizontal sync signal, configure
all MAX7428s for SYNCIO as an input (Figure 15).
