ch7008a Chrontel, ch7008a Datasheet - Page 14

• Manufacturer Part Number: ch7008a
• Description: Digital Pc To Tv Encoder
• Manufacturer: Chrontel

CHRONTEL
4.4 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 10 and shown in Figure 8. (See Figures 11 through 16 for
illustrations of composite and S-Video output waveforms).
4.4.1 CCIR624-3 Compliance
The CH7008 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 mode, not in slave mode when the graphics
• It is assumed that gamma correction, if required, is performed in the graphics device which establishes the color
• All modes provide the exact number of lines called out for NTSC and PAL modes respectively, except mode 21,
• 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
For this table and all subsequent figures, key values are:
Note:
14
Table 10. NTSC/PAL Composite Output Timing Parameters (in mS)
Symbol
device generates these frequencies.
reference signals.
which outputs 800x600 resolution, scaled by 3:4, to PAL format with a total of 627 lines (vs. 625).
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.
G
A
B
C
D
E
F
H
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.
Description
Front Porch
Horizontal Sync
Breezeway
Color Burst
Back Porch
Black
Active Video
Black
NTSC
287
287
287
287
340
340
340
0
Level (mV)
PAL
300
300
300
300
300
300
300
0
201-0000-027 Rev 2.8, 6/24/2004
1.49 - 1.51
4.69 - 4.72
0.59 - 0.61
2.50 - 2.53
1.55 - 1.61
0.00 - 7.50
37.66 - 52.67
0.00 - 7.50
NTSC
Duration (uS)
CH7008A
1.48 - 1.51
4.69 - 4.71
0.88 - 0.92
2.24 - 2.26
2.62 - 2.71
0.00 - 8.67
34.68 - 52.01
0.00 - 8.67
PAL