AK8815 Datasheet, PDF (19/37 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Encoder

ASAHI KASEI
( 1-3 ) HSYNC and VSYNC relation in each Frame
( 1 ) NTSC ( Frame ) 525 Line 480 active lines
The First Field ( ODD )
263 lines
525
1
2
3
4
5
6
7
HSYNC
[AK8815/16]
240 lines
22
23
261
262
263
264
VSYNC
* ) VSYNC negative-going occurs during HSYNC = L at Line 4.
VSYNC positive-going can occurs at arbitrary location, but keep VSYNC low for 3 line duration time as a rough idea.
The Second Field ( EVEN )
262 lines
263
264
265
266
267
268
269
270
HSYNC
240 lines
285
286
524
525
1
2
VSYNC
High
* ) VSYNC negative-going is not required for the Second Field. It is required for the First Field only.
When VSYNC is input in the specified timing (described below ) at the Second Field, the line and the field are set once as the Second Field.
But since the Burst cycle etc. is referenced to the First Field, VSYNC synchronization
cannot be made with the Second Field only. System synchronization must be made to reference the VSYNC synchronization at the First Field.
When to input VSYNC at the Second Field, it should be done after the first 1/2 H of the 266^th Line and before the falling edge of the 267^th HSYNC ( if HSYNC falling
edge timing of the 266^th Line is counted as the 0^th clock, VSYNC should be fallen after the 780^th Clock and before the 1559^th Clock ).
MS0331-E-00
19
2004 / 08