RIVA128ZX Datasheet, PDF (61/85 Pages) STMicroelectronics – 128-BIT 3D MULTIMEDIA ACCELERATOR

128-BIT 3D MULTIMEDIA ACCELERATOR
RIVA128ZX
11.6 TV OUTPUT SUPPORT
Reference clock options
The RIVA128ZX supports two synthesizer refer-
ence clock frequencies; 13.5MHz and
14.31818MHz. The reference clock frequency is
determined by a crystal or reference clock con-
nected to the XTALIN and XTALOUT pins. Where
TV-out is supported, XTALOUT should be driven
by a 13.5MHz reference clock derived from an ex-
ternal NTSC/PAL clock source as illustrated in
Figure 67. The clock frequency should match the
power-on configuration setting described in Sec-
tion 10, page 55.
PAL/NTSC TV interface
The RIVA128ZX supports TV output through an
external Analog Devices AD722 PAL/NTSC RGB
encoder chip as shown in Figure 67. A MicroClock
Figure 67. TV output implementation
MK2715 NTSC/PAL clock chip provides a com-
mon source for synchronization of the pixel and
subcarrier clocks. In TV output modes the
RIVA128ZX XTALOUT pin must be externally
driven from the MK2715 reference clock output,
with XTALIN tied to GND.
The MK2715 requires a number of external com-
ponents for proper operation. For crystal input a
parallel resonant 13.5000MHz crystal is recom-
mended, with a frequency tolerance of 50ppm or
better. Capacitors should be connected from X1
and X2 to GND as shown in Figure 67. Alternative-
ly a clock input (e.g. ClockCan) can be connected
to X1, leaving X2 disconnected. Further details are
given in the MK2715 datasheet [8].
5V
220Ω
R
XTALIN
G
B
RIVA128ZX
VIDHSYNC
RIN
220µF
75Ω
YOUT
GIN
220µF
75Ω
COUT
BIN
220µF
75Ω
CVOUT
75Ω
AD722 TV
RGB Encoder
HSYNC
XTALOUT
FIN
330Ω
33Ω
REFOUT
33Ω
4XCLK
27pF
X1/ICLK
MK2715
NTSC/PAL
Clock Source
27pF
X2
13.50000MHz
crystal
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