AK8851 Datasheet, PDF (20/80 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

ASAHI KASEI
[AGCT1:AGCT0]-bit:
* AGC time constant is set by [AGCT1:AGCT0]-bit.
[AGCT1:AGCT0]-bit
Time constant of AGC
[00]
Disable
[01]
Fast
[10]
Middle
[11]
Slow
[AK8851]
Note
PGA control Register is valid
[AGCC]-bit:
*[AGCC]-bit sets the non-sensing range ( coring level ) of AGC.
[AGCC]-bit
non-sensing range of AGC
0
+/-2-bit
1
+/-3-bit
Note
[AGCFRZ]-bit:
* This bit controls the AGC freeze function.
When [AGCFRZ]-bit is stopgap gain values are maintained.
[AGCFRZ]-bit
Status of AGC
Note
0
AGC function is working
Invalid when AGC function is disable.
1
AGC function is frozen
Current AGC Value is kept
(footnote)
AGC gain set function is set based on the SYNC signal level only.
When the input signal’s SYNC signal level is small but still at a valid level, PGA gain set by the AGC function becomes larger
than normal.
If the decoded output code exceeds 254, [PKWHITE]-bit in [Status 1 Register](R)[Sub Address 0x16] or [OVCOL]-bit
becomes “1”, which indicates an overflow of the decoded data. As for the input level overflow, it is described in a later
section.
MS0244-E-03
20
Confidential
2005 / 07