AK8856VN Datasheet, PDF (77/98 Pages) Asahi Kasei Microsystems – NTSC/PAL Video Decoder

ASAHI KASEI
[AK8856 Preliminary Data Sheet]
Notification Function of Internal Conditions
The AK8856 has a Status Register (R/W) [Sub Address 0x10] to notify externally the AK8856 internal
condition. Bit allocation of Status Register is as follows.
Sub Address 0x10
bit 7
bit 6
VBWSSDET EXTDET
bit 5
CCDET
bit 4
AGCSTS
bit 3
VLOCKSTS
bit 2
PKWHITE
bit 1
COLKILST
bit 0
NSIG
(1) No Signal Decision
The AK8856 detects when no signal input is present. When there is no input signal, the data output goes to
Black level output (Y = 0x10, Cr / Cb = 0x80). This result is flagged by the output pin NSIG and the [NSIG] bit of
Status Register. The output logical state is:
Signal condition
With signal input
No signal input
[NOSIG] bit
0
1
NSIG pin
0
1
(2) COLKILST
This indicates that the Color Killer Function has been activated, since the color signal level is very small.
[COLKIL]-bit
0
1
Input level
Normal signal
Color Killer is enabled
Condition
(3) Input Level Overflow Notification Function
This function is activated when the numerical result of the luminance signal exceeds 255.
[PKWHITE] bit
When an overflow of the luminance signal is detected, this bit is set to “1”.
[PKWHITE]- bit
0
1
Input level
Input signal overflow occurred
No input overflow occurred
(4) Color PLL Status
This indicates a PLL lock condition with the input Color Burst signal.
[CPLLLCK] bit
[CPLLLCK] bit
Input level
0
Locked with input Color Burst signal
1
Not locked with input Color Burst signal
(5) AGC Status
This indicates the status of adaptive AGC.
[AGCSTS] bit
[AGCSTS]-bit
Input level
0
Operating in Sync AGC
1
Operating in Peak AGC
Condition
Condition
Condition
MS0522-E-00
77
2006/Dec