ML6426 Просмотр технического описания (PDF) - Fairchild Semiconductor
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ML6426
Fairchild Semiconductor
ML6426 Datasheet PDF : 17 Pages
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DATA SHEET
ML6426
Typical Applications
Reconstruction filter selection for HDTV and
VGA signal filtering
The filtering requirements for HDTV and VGA standards
vary depending on the resolution of the image to be dis-
played, and its refresh rate. The actual refresh rate of the dis-
play is not necessarily the same as the transmission rate of
the frames of images. Some formats use a frame rate of
30Hz, but the display of those formats cannot be scanned
onto the CRT at 30Hz. Excessive large area flicker would
result. Such kinds of flicker can be seen on a PAL display
with its brightness set high. To avoid this, the video will need
to be stored in a frame buffer. This buffer already exists in
the MPEG decoder of HDTV systems, so there is no cost
penalty. The buffer is read out at twice the rate as the frame
rate for 30Hz systems, thus getting us a refresh rate of 60Hz.
Similar things are done for the 24Hz frame rate formats to
boost them to a 60Hz refresh rate.
Table 1. HDTV / Advanced TV Applications: (From Table 10.3 from ATSC document A54)
Pixels
Vertical Lines
Aspect Ratio
Picture Transmission Rate
1920
1080
16:9
60I, 30P, 24P
1280
720
16:9
60P, 30P, 24P
704
480
16:9 and 4:3
60P, 60I, 30P, 24P
640
480
4:3
60P, 60I, 30P, 24P
P=progressive scan, I=interlaced scan
Table 2. Choosing the Correct Reconstruction Filter and Video Amplifier for TV Applications, ML6426 options
SMPTE
1920
1280
704
704
1080
720
480 (Note 1)
480
30P, 24P
60P, 30P,
24P
60I
60P, 30P,
24P
60Hz
60Hz
60Hz
60Hz
640
480 (Note 1)
60I
60Hz
640
480
60P, 30P, 60Hz
24P
P=progressive scan, I=interlaced scan, na = not available
70.6KHz 162MHz
47.1KHz 60MHz
81MHz
30MHz
15.7KHz 13.5MHz 6.75MHz
31KHz 27MHz 13.5MHz
15.7KHz 24.5MHz 12MHz
31KHz 12.27MHz 6MHz
Notes
1. NTSC display rates, can be fed directly into NTSC encoder (set top box)
2. 60 Hz also includes 59.94Hz
3. Custom frequencies ranging ± 3 to 6MHz can be special cut to order
N/A
ML6426-5
ML6426-4
ML6426-1
ML6426-2
ML6426-4
ML6426-2
ML6426-1
REV. 3A August 2004
7
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