CH7003B Datasheet, PDF (18/50 Pages) List of Unclassifed Manufacturers – Digital PC to TV Encoder

CHRONTEL
CH7003B
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 14 and shown in Figure 10. (See Figure 13 through 18 for
illustrations of composite and S-Video output waveforms.)
CCIR624-3 Compliance
The CH7003 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 psuedo-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.
Table 14. NTSC/PAL Composite Output Timing Parameters (in µS)
Symbol
Description
Level (mV)
NTSC
PAL
Duration (uS)
NTSC
PAL
A
Front Porch
B
Horizontal Sync
C
Breezeway
D
Color Burst
E
Back Porch
F
Black
G
Active Video
H
Black
287
300
1.49 - 1.51
1.48 - 1.51
0
0
4.69 - 4.72
4.69 - 4.71
287
300
0.59 - 0.61
0.88 - 0.92
287
300
2.50 - 2.53
2.24 - 2.26
287
300
1.55 - 1.61
2.62 - 2.71
340
300
0.00 - 7.50
0.00 - 8.67
340
300
37.66 - 52.67
34.68 - 52.01
340
300
0.00 - 7.50
0.00 - 8.67
For this table and all subsequent figures, key values are:
Note:
1. RSET = 360 ohms; V(RSET) = 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.
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201-0000-023 Rev.4.1, 8/2/99