UPD16681A Просмотр технического описания (PDF) - NEC => Renesas Technology

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UPD16681A

LCD CONTROLLER/DRIVER FOR DOT MATRIX DISPLAY OF JIS LEVEL 1 AND JIS LEVEL 2 KANJI SETS

NEC => Renesas Technology 

µPD16681A

Figure 4−3. Using Internal Power Supply Select and D/A Converter

VDD

VDD

DACHA

AMPIN(+)

OPEN

D/A

converter

VREF

+

To internal drive circuit

−

AMPIN(−)

AMPOUT

Rth

VLC1

R2

R1

C1

4.2.3 When using an external power supply (VEXT = H)

When an external power supply is used for the LCD driver voltage, the op amp incorporate in the µPD16681A (used

for the LCD driver voltage) is in OFF mode. Consequently, the LCD driver’s op amp and D/A converter function

cannot be used when using an external power supply. Instead, regulate the LCD driver voltage by inputting directly

to the VLCD and VLC1 pins.

Cautions 1. Maintain the following relation for the voltage input to the VLCD and VLC1 pins : VLCD > VLC1

2. Since the DACHA, AMPIN(+), and AMPIN(−) pins are CMOS inputs, they should be fixed either high or

low.

3. The AMPOUT pin should be left unconnected.

4.3 Reference Voltage

4.3.1 When using internal power supply (VEXT = L)

When using the internal power supply, the µPD16681A’s on-chip divider resistor is used to create the six-level

potential (VLC1 to VLC5, and VSS) required for the LCD driver.

4.3.2 When using an external power supply (VEXT = H)

When use of an external power supply has been selected, the op amp incorporated in the µPD16681A for the LCD

driver level power supply is in OFF mode, so a reference potential must be directly input to VLC1 to VLC5.

Ordinarily, these levels are generated by dividing the resistance. Since large resistance values result in poorer LCD

display quality, be sure to select a resistance value that suits the type of LCD panel to be used.

The display quality can be improved by connecting capacitors between the level pins and ground pins. As with the

resistance values described above, the capacitance values of the capacitors should be selected to suit the divided

resistance values and the type of LCD panel to be used.

10

Data Sheet S14207EJ3V0DS

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