YGV639 Ver la hoja de datos (PDF) - Yamaha Corporation

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YGV639

Video Controller 1 withEnhanced Functions

Yamaha Corporation 

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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