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CHRONTEL
CH7006C
18
201-0000-026 Rev 2.1, 8/2/99
NTSC and PAL Operation
Composite and S-Video outputs are supported in either NTSC or PAL format. The general parameters used to
characterize these outputs are listed in
Table 13
and shown in
Figure 10
. (See
Figure 13
through
18
for
illustrations of composite and S-Video output waveforms.)
CCIR624-3 Compliance
The CH7006 is predominantly compliant with the recommendations called out in CCIR624-3. The following are the
only exceptions to this compliance:
The frequencies of Fsc, Fh, and Fv can only be guaranteed in master or pseudo-master modes, not in slave mode
when the graphics device generates these frequencies.
It is assumed that gamma correction, if required, is performed in the graphics device which establishes the color
reference signals.
All modes provide the exact number of lines called out for NTSC and PAL modes respectively, except mode 21,
which outputs 800x600 resolution, scaled by 3:4, to PAL format with a total of 627 lines (vs. 625).
Chroma signal frequency response will fall within 10% of the exact recommended value.
Pulse widths and rise/fall times for sync pulses, front/back porches, and equalizing pulses are designed to
approximate CCIR624-3 requirements, but will fall into a range of values due to the variety of clock frequencies
used to support multiple operating modes
For this table and all subsequent figures, key values are:
Note:
1.
ISET = 360 ohms; V(ISET) = 1.235V; 75 ohms doubly terminated load.
2.
Durations vary slightly in different modes due to the different clock frequencies used.
3.
Active video and black (F, G, H) times vary greatly due to different scaling ratios used in different modes.
4.
Black times (F and H) vary with position controls.
Table 13. NTSC/PAL Composite Output Timing Parameters (in
μ
S)
Symbol
Description
Level (mV)
Duration (uS)
NTSC
PAL
NTSC
PAL
A
Front Porch
287
300
1.49 - 1.51
1.48 - 1.51
B
Horizontal Sync
0
0
4.69 - 4.72
4.69 - 4.71
C
Breezeway
287
300
0.59 - 0.61
0.88 - 0.92
D
Color Burst
287
300
2.50 - 2.53
2.24 - 2.26
E
Back Porch
287
300
1.55 - 1.61
2.62 - 2.71
F
Black
340
300
0.00 - 7.50
0.00 - 8.67
G
Active Video
340
300
37.66 - 52.67
34.68 - 52.01
H
Black
340
300
0.00 - 7.50
0.00 - 8.67