AK8855 Datasheet, PDF (21/81 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

[ASAHI KASEI]
AK8855
Color Killer
Chroma Signal Quality is decided by Color Burst level of input signal.
When the Chroma Signal level is lower than a threshold level, it is decided to be improper signal and input signal
is all processed as luminance signal.
In this case, Cb / Cr data from the AK8855 is a fixed 0x80 in 601 level.
Color Killer functions when Color Burst level becomes lower than approximately -23 dB.
Bit allocation of Control Register ( R/W ) [ Sub Address 0x04 ] is as follows.
Sub Address 0x04
bit 7
bit 6
CNTSEL
DTFIX
0
0
bit 5
ODEV
0
bit 4
bit 3
FRMRT1 FRMRT0
Default Value
0
0
bit 2
COLKIL
0
Default Value: 0x00
bit 1
bit 0
ACC
AGC
0
0
[ COLKILL ]-bit
[ COLKILL ]-bit selects enable / disable of Color Killer function.
COLKILL-bit
Color Killer Function
0
Enable
1
Disable
Condition
Frame Rate setting
This is to set the Frame Rate.
Frame Rate setting is done by [ FRMRT1 : FRMRT0 ]-bits of Control Register ( R/W ) [ Sub Address 0x04 ].
[FRMRT1:FRMRT0]-bit
00
01
10
11
Frame Rate
30/25(525/625)
15/12.25(525/625)
7.5/6.25(525/625)
Reserved
Condition
Even / Odd Field selection
Even / Odd Field setting is done for QVGA / CIF / QCIF output modes.
Setting is done by [ODEV ]-bit of Control Register ( R/W ) [ Sub Address 0x04 ].
ODEV-bit
0
1
ODD Field
EVEN Field
Condition
Power Saving Mode at Low Frame Rate
Power dissipation during no-output period is reduced when Frame Rate is dropped.
Setting is done by [ DTFIX ]-bit of Control Register ( R/W ) [ Sub Address 0x04 ].
DTFIX-bit
0
1
Power Saving mode
Disabled
Enable
Condition
MS0319-E-03
21
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