YGV639 Datasheet, PDF (11/34 Pages) YAMAHA CORPORATION – Video Controller 1 with Enhanced Functions

YGV639
Clock
There are three clocks which are used in VC1E.
(1) Dot Clock : clock for picture display and picture data output.
(2) System Clock : internal clock (about 81MHz) for picture processing in VC1E.
(3) Decoder Clock : internal clock (about 27MHz) that is used when decoding analog video signals.
These three clocks can be generated from a single crystal resonator.
PLL Reference Clock Crystal Connection Pins
XIN (Input), XOUT (Output)
VC1E oscillates clocks by connecting a crystal resonator to XIN and XOUT pins. When using the
externally-oscillated clock, input it to XIN pin. In this case, nothing should be connection to XOUT pin.
When generating a dot clock, system clock and decoder clock from a single clock input, connect a crystal
resonator of the same frequency as that of the dot clock to this XIN pin or input the clock.
● The frequency that can be oscillated with XIN and XOUT pins is 6MHz to 30MHz.
● The clock frequency that can be input to XIN pin ranges from 6MHz to 40MHz.
Below is shown the external circuit for the clock oscillation with a crystal resonator.
VDD33(pin48) XOUT(pin49)
Rf
XIN(pin50) VSS(pin51)
3.3V
Rd
Crystal Resonator
C1
C2
Board GND
● C1, C2: External load capacity
● Rf: Feedback resistor
● Rd: Damping resistor
„ Reference values of the oscillator circuit constants
Crystal Resonator
Rf
Rd
C1, C2
KYOCERA KINSEKI
CX8045GB 8MHz
1MΩ
1.6kΩ
12pF
KYOCERA KINSEKI
CX8045GB 14MHz
1MΩ
820Ω
12pF
Note: The above constants do not always guarantee the oscillation as they are the reference values based on
the evaluation under the particular circumstance. For actual application, please ask the resonator’s
manufacturer to evaluate the resonator with it mounted on a board.
In order to secure stable operation of the oscillation circuit, it is recommended to take the following
measures for preventing noise.
(1) LSI and crystal resonator, etc. should be placed as close to each other as possible to shorten the length
of wiring.
(2) GND of the oscillation circuit must be directly connected to VSS(pin51) of the LSI.
(3) The oscillation circuit must be separated from a wiring pattern in which a large current flows.
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