4/2Fsc - Hitachi H8S/2199 Hardware Manual

Table 29.6 Dot Clock Cycle
TV Format
M/NTSC, 4.43-NTSC, M/PAL, N/PAL
B, G, H/PAL, I/PAL, D, K/PAL, SECAM
29.9.4

4/2fsc

1. 4/2fsc Oscillator
The 4/2fsc oscillator generates color signals for text display mode, and also generates the
internal sync signal. A crystal oscillator can be connected, or an external clock can be input.
The 4/2fsc frequency should be appropriate for the TV format. If an inappropriate frequency is
used, or if no 4/2fsc signal is input, OSD operation is not guaranteed.
Circuit constants should be chosen such that frequency deviation, including temperature
effects, is within ±30 ppm.
An example of connection of a crystal oscillator appears in figure 29.21; an example of input
of an external clock is shown in figure 29.22.
Power-down
mode controller
Note: Rf = 1 MΩ typ.
Crystal should be at a frequency appropriate for the TV format.
C1, C2 should be specified such that frequency deviation, including temperature effects, is less than
±30 ppm.
Figure 29.21 Example of Connection of a 4/2fsc Crystal Oscillator
4/2fsc in
Dot Clock Cycle
Reference Clock:
576 × × × × fh
110 ns (9.06 MHz)
111 ns (9.00 MHz)
Rf
Rev. 1.0, 02/00, page 873 of 1141
Reference Clock:
448 × × × × fh
142 ns (7.06 MHz)
143 ns (7.00 MHz)
C1
Crystal
C2