Rev. 1.0, 02/00, page 764 of 1141
Bit 2
Digital LPF Control (DLPFON): Specifies the digital LPF function, which masks noise
components of the Vsync signal in a weak field. The digital LPF logically ORs the Csync signal
(Vsync signal) and the SEPH signal that is separated by the digital H separation counter, then
inputs the ORed result to the digital V separation counter. This function prevents Vsync detection
delay and Vsync detection miss in a weak field. For the timing, refer to section 27.2.5, Vertical
Sync Signal Threshold Register (VVTHR).
Bit 2
DLPFON
Description
0
The digital LPF does not operate
(Initial value)
1
The digital LPF operates
Bit 1
Reserved: Cannot be modified and is always read as 0. When 1 is written to this bit,
correct operation is not guaranteed.
Bit 0
Reference Clock Frequency Select (FRQSEL): Selects the frequency of the reference
clock for the AFC: 576 times or 448 times the horizontal sync signal frequency. To obtain a
desired reference clock frequency, connect an external circuit of a value suitable for the desired
frequency to the AFCosc and AFCpc terminals, and select the division ratio of the frequency
dividing counter with this bit. This AFC reference clock is also used as the dot clock for the OSD;
change this frequency to adjust the dot width of the display characters. Note, however, that the
data slicer will not operate when 448 times the horizontal sync frequency is selected. For details,
refer to section 27.3.6, Automatic Frequency Controller (AFC).
Bit 0
FRQSEL
Description
0
576 times the horizontal sync frequency
(Initial value)
1
448 times the horizontal sync frequency