Rev. 1.0, 02/00, page 795 of 1141
Table 27.4
Reference Hsync Signal for AFC
AFC
Reference
Hsync
Signal
Data Slicer
Operation
OSD
Operation
Field
Detection
V Comple-
ment and
Mask
Counter
HCKSEL
HSEL
VCKSL
External
Hsync
signal
Operates/
Stops
Super-
imposed
mode
Operates
Twice the
frequency of
the AFCH
0
0
0
Internally
generated
Hsync
signal
Stops
Text
display
mode
Stops
Twice the
frequency of
the OSCH
0
1
1
External
Hsync
signal
*
Operates
Text
display
mode
Operates
Twice the
frequency of
the AFCH
1
0
0
Note:
*
In this case, the Hsync and Vsync signals must be dedicated separation inputs, with both
signals having equal cycles and pulse widths. The FRQSEL bit in the SEPIMR register
must be cleared to 0.
(4) External Circuit Examples
Figures 27.21 and 27.22 show external circuit examples of the AFC.
10pF
AFCosc
AFCpc
AFCLPF
6.8
µ
H
0.01
µ
F
1/2OVcc
VCO
0.01
µ
F
4.7
µ
F
+
+
470
Ω
2.4k
Ω
Note: Reference values are shown.
Phase error signal
Reset, active,
or sleep
Figure 27.21 Circuit Example for a 576
××××
fh Reference Clock