UPD6464ACS データシートの表示（PDF） - NEC => Renesas Technology

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UPD6464ACS

ON-SCREEN CHARACTER DISPLAY CMOS LSI FOR 12-LINE, 24-COLUMN DECK-TYPE VCR

NEC => Renesas Technology 

µPD6464A,6465

2.7 Oscillation Method Control Command

The µPD6464A, 6465 can select a crystal for internal video signal generation or a ×4 multiplier.

D7 D6 D5 D4 D3 D2 D1 D0

0

1

0

1

0

0

Xfc

0

Oscillation method control bit

Xfc

Function

0 Quadruple oscillation

1 4fSC crystal oscillation

• Oscillation method control bit

In the µPD6464A and 6465, the oscillation method can be selected from ×4 multiplication oscillation and 4fSC crystal

oscillation with the oscillation method control command.

When ×4 multiplication oscillation is selected, the fSC signal must be input from the FSCI pin. The 4fSC signal is

generated from an external LC resonator and an internal circuit of the µPD6464A and 6465. The phase of four-

divided 4fSC signal generated via LC oscillation is compared with that of the fSC signal that is input to the FSCI pin.

The obtained phase error is converted to a voltage value, and then output from the FSCO pin. In the circuit shown

in 8. APPLICATION CIRCUIT DIAGRAM (1) In ×4 multiplication oscillation, the 4fSC signal synchronizing with

the external fSC signal is generated by changing the capacitance of varactor diodes with this voltage that is based

on a phase error.

When 4fSC crystal oscillation is selected, the FSCI and FSCO pins are not used. These pins should be connected

as follows.

FSCI pin (pin 9) : Connect to GND or VDD.

FSCO pin (pin 10) : Leave open.

Remark The scanning method in the internal video signal mode is non-interlacing. With the NTSC and PAL-

M methods, the number of scanning lines is 263. With the PAL and PAL-N method, it is 312.

16

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