AK8856 Datasheet, PDF (31/105 Pages) Asahi Kasei Microsystems – NTSC/PAL Digital Video Decoder

ASAHI KASEI
[ AK8856 ]
Color Killer
The Chroma Signal Quality is determined by the Color Burst level of the input signal. When the Chroma Signal
level is lower than a threshold level, it is regarded as an improper signal, and the input signal is processed as
strictly a luminance signal. In this case, Cb / Cr data from the AK8856 is fixed at 0x80 in 601 level.
Color Killer operation is selectable from the following 3 conditions, and it is set by the CKILSEL 1:0 bits:
(1) When the Color Burst level is lower than approximately – 23 dB.
(2) When the PLL for Color decoding cannot be locked.
(3) When either condition (1) or (2) is met.
Color Killer is set ON or OFF by the Control 2 Register (R/W) [Sub Address 0x04]. Color Killer operating
conditions are set by the CKILSEL[1:0] bit of the Control 1 Register (R/W) [Sub Address 0x03].
Sub Address 0x04
bit 7
bit 6
CNTSEL
NSIGDEF
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
This bit enables or disables the Color Killer function.
COLKILL-bit
Color Killer Function
0
Enable
1
Disable
Condition
Sub Address 0x03
bit 7
bit 6
Reserved
VDFLD
0
0
bit 5
AGCTR
0
bit 4
bit 3
AGCC1
AGCC0
Default Value
0
0
bit 2
CKILSEL1
Default Value: 0x00
bit 1
bit 0
CKILSEL0
YCSEP
0
0
0
[CKILSEL 1:0]-bit
CKILSEL1:0-bit
00
01
10
11
Color Killer Operation
when either Color Burst level is lower than –23 dB or when PLL for
Color decoding cannot be locked.
when PLL for Color decoding cannot be locked.
when Color Burst level is lower than approximately – 23 dB.
Reserved
Note
AK8855 compatible
Rev-01
31
2007/03