UPD6465CS datasheet(27/52 Pages) NEC

27 / 52 page

µPD6464A,6465

ADJUSTING

This section describes how to adjust each circuit of the

µPD6464A, 6465. When performing adjustment, the

TEST pin (pin 19) must be connected to VCC.

4.1

Adjusting Oscillation Frequency

4.1.1

Adjusting

×4 multiplier and crystal oscillation frequency

The

µPD6464A, 6465 generate the internal video signal by means of quadruple oscillation of 4fSC or crystal

oscillation.

The oscillation frequency of 4fSC can be output from the VSYO pin (pin 16) by using the test mode command.

Adjustment

•

Connect the TEST pin (pin 19) to VCC (normally, connect this pin to GND).

•

Input the following command. The quadrupled or crystal oscillation frequency will be output from the VSYO pin

(pin 16). To clear the test mode, either transfer the test mode clear command, or connect the TEST pin to GND.

•

In this case, the VSYO pin does not function as a vertical synchronization signal output pin.

•

Adjust the frequency with a capacitor (or coil), connected to XOSI pin (pin 12), shown in 8. APPLICATION CIRCUIT

DIAGRAM using a frequency counter.

Crystal oscillation frequency output command (2-byte command)

D15

D14

D13

D12

D11

D10

1011000000111111

4.1.2

Adjusting LC oscillation frequency (dot clock)

The

µPD6464A, 6465 create the dot clock of characters by means of LC oscillation.

The LC oscillation frequency can be output from the HSYO pin by using the test mode command, in the same

manner as when adjusting the crystal oscillation frequency described in 4.1.1.

Adjustment

•

Connect the TEST pin (pin 19) to VCC (normally, connect this pin to GND).

•

Input the following command. The LC oscillation frequency will be output from HSYO pin (pin 15). To adjust the

LC oscillation frequency, turn OFF display. When display is ON and while Hsync is low, oscillation is stopped and

the accurate oscillation frequency cannot be obtained (when using a frequency counter).

To clear the test mode, either transfer the test mode clear command, or connect the TEST pin to GND.

•

In this case, the HSYO pin does not function as a horizontal synchronization signal output pin.

•

Adjust the frequency with a trimmer capacitor (or coil), connected to OSCIN pin (pin 6) shown in 8. APPLICATION

CIRCUIT DIAGRAM using a frequency counter.

LC oscillation frequency output command (2-byte command)

D15

D14

D13

D12

D11

D10

1011000000111111

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