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For the UPD6464A OSD IC, is fsc input required?

Latest Updated:01/01/2007

Question:

For the UPD6464A OSD IC, is fsc input required?

Answer:

It is required when ×4 multiplication oscillation is selected by the oscillation method control command. This is because the 4fsc signal generated according to the fsc input is used as the reference clock for synchronization signal generation when the internal video signal mode is set, and the fsc signal generated by dividing this 4fsc signal by four is used as the reference clock for internal video signal generation and for the synchronization separation circuit (when the external video signal mode is set).
Be sure to use the crystal oscillation control command to set crystal oscillation to ON when displaying characters.
In the uPD6464A or uPD6465, the on-chip ×4 multiplication oscillation circuit enables the mounting area and cost to be reduced by using an LC oscillator instead of an expensive crystal oscillator.
Also, since the oscillation precision is decreased due to low Q with just the LC oscillator, the stable oscillation at 4fsc is secured by a phase locked loop (PLL) formed by inputting fsc.
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