ml6440 Micro Electronics Corporation, ml6440 Datasheet - Page 12

• Manufacturer Part Number: ml6440
• Description: Multi-standard 8-bit Adaptive Digital Input Comb Filter
• Manufacturer: Micro Electronics Corporation

ML6440
TYPICAL APPLICATIONS
Figure 7 depicts an application block diagram of the
ML6440. The ML6440 is easy to use in most standard
video applications in conjunction with an 8-bit A/D
converter or digital data for analog and digital
applications. High speed digital layout should be
observed. Pay special attention that the outputs are not
loaded beyond a 2mA load. An A/D, if used, should have
at least seven effective bits at Nyquist rates for good
quality video. Please note that startup of the part will
require at least two lines to flush out the line delays and
about 10 lines for the adaption to adjust. The automatic
adaption thresholding should not be discernible in most
video applications, but can be defeated with the fixed
adaption levels. In applications using video tape recorders
the comb may not be effective and can make results worse
if time jitter exceeds the clock period 70ns. Jitter of this
magnitude would misalign the line delays, making the
combing and adaption incorrect. In this case combing
should be turned off.
POWER SUPPLY REQUIREMENTS
The AV
0.4V drop from a 5V supply. Alternately, a 7.5
can be used instead of the diode. The AV
a 1µF surface mount capacitor to ground. See Figure 7.
Bypass caps must be within 3mm of the chip pins they
bypass. Direct traces are necessary.
Digital Video Values of Sync Tip and Peak White
As recommended by SMPTE and ITU-R BT.601, the
minimum value of digitized sync tip is decimal 16. The
maximum value of digitized video is decimal 255 (235
recommended is by SMPTE which allows for overshoots in
video). Normally, peak white is at 235; this avoids
clipping due to overshoots.
Figure 8 presents Micro Linear’s entire solution for
optimized video application designs. The ML6430 can be
used as high performance line lock clock that’s capable of
12
CC
must be fed through a Schottky diode of about
CC
pin also needs
W
resistor
generating horizontal and vertical syncs and a variety of
system clocks using common reference frequency crystals.
The ML6401 is a low cost A/D converter. The ML6421 is a
three channel filter with sinx/x equalization. The ML6424
is a precision filter used as a clamp circuit and anti-
aliasing filter. (See Micro Linear's ML6440EVAL for more
information)
Test Patterns
When viewing test patterns, the fixed thresholds may give
better performance, since the automatic adaptive
threshold algorithm was optimized for live video.
There are various specific application uses of the ML6440
SmartComb :
Figure 9 illustrates the use of the ML6440 in a big screen
TV application. In this application, the ML6440 offers
automatic self-adjusting thresholds to optimize Y/C
separation while minimizing artifacts for a wide variety of
live video material without fixed threshold limitations. The
ML6440 supports S-video bypass or luma and chroma
separation enhancement, simplifying design for high-
performance video source selection.
Figure 10 illustrates the use of the ML6440 in HDTV and
NTSC application. In hybrid TV sets, where both NTSC
and HDTV will be prevalent, the ML6440 SmartComb can
serve as a high-performance Y/C NTSC-separator in a
NTSC-HDTV video receiver.
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Large screen TVs
HDTV
Video projection
MPEG encoding
Video conferencing
Imaging and video capture
Format converters
Time base correctors
Professional video
Line doublers and quadrapulers