AK8853XQ Datasheet, PDF (23/70 Pages) Asahi Kasei Microsystems – NTSC/PAL/SECAM Digital Video Decoder

[AK8853XQ/ VN]
ACTSTA[2:0]-bits: Adjustment of active video start position
ACTSTA[2:0]-bits
Line and active video start
[001]
525 Line
625 Line
124^th sample
134^th sample
[010]
525 Line
625 Line
125^th sample
135^th sample
[011]
525 Line
625 Line
126^th sample
136^th sample
[000]
525 Line
625 Line
123^th sample
133^th sample
[101]
525 Line
625 Line
120^th sample
130^th sample
[110]
525 Line
625 Line
121^th sample
131^th sample
[111]
525 Line
625 Line
122^th sample
132^th sample
Approximate delay/advance (ns)
74, delay
148, delay
222, delay
Default value (normal position)
222, advance
148, advance
74, advance
[100]
Reserved
Reserved
–
With the default value, the start position is as follows (with ITU-R BT.601 format compliance).
OH
OH
122samples(525Line)
Active video start
132samples(625Line)
Active video start
7.7 Auto Gain Control_AGC
The AGC of the AK8853 measures the size of the input sync signal (i.e., the difference between the sync
tip and pedestal levels), and adjusts the PGA value to bring the sync signal level to 286^a or 300^b mV.
The AGC function amplifies the input signal to the appropriate size and enables input to the AD
converter. The AGC function in the AK8853 is adaptive, and thus includes peak AGC as well as sync
AGC. Peak AGC is effective for input signals in which the sync signal level is appropriate and only the
active video signal is large.
a _{NTSC-M, J; NTSC-4.43; PAL-M}
b _{PAL-B, D, G, H, I, N; PAL-Nc; PAL-60; SECAM}
AGCT[1:0]-bits: Settings for AGC time constant
AGCT[1:0]-bits
Time constant
Notes
[00]
Disable
AGC OFF, PGA register enabled.
[01]
Fast
T= 1Field
[10]
Middle
T= 7Fields
[11]
Slow
T= 29Fields
T is the time constant.
Manual setting of the PGA register is possible only if AGC is disabled.
Rev-E-00
23
2008/01