4559 datasheet(46/148 Pages) RENESAS

46 / 148 page

Rev.1.04

Aug 23, 2007

Page 46 of 146

REJ03B0188-0104

4559 Group

(5) LCD power supply circuit

Select the LCD power supply circuit suitable for the using LCD

panel.

The LCD power supply circuit is fixed by the followings;

• The internal dividing resistor is controlled by bit 0 of register

L2.

• The internal dividing resistor is selected by bit 3 of register L1.

• The bias condition is selected by bits 0 and 1 of register L1.

• Internal dividing resistor

The 4553 Group has the internal dividing resistor for LCD power

supply.

When bit 0 of register L2 is set to ì0î, the internal dividing

resistor is valid. However, when the LCD is turned off by setting

bit 2 of register L1 to ì0î, the internal dividing resistor is turned

off.

The same six resistor (r) is prepared for the internal dividing

resistor.

According to the setting value of bit 3 of register L1 and using

bias condition, the resistor is prepared as follows;

•L13 = “0”, 1/3 bias used: 2r × 3 = 6r

•L13 = “0”, 1/2 bias used: 2r × 2 = 4r

•L13 = “1”, 1/3 bias used: r × 3 = 3r

•L13 = “1”, 1/2 bias used: r × 2 = 2r

•SEG0/VLC3 pin

The selection of SEG0/VLC3 pin function is controlled with the

bit 3 of register L2.

When the VLC3 pin function is selected, apply voltage of VLC3 <

VDD to the pin externally.

When the SEG0 pin function is selected, VLC3 is connected to

VDD internally.

• SEG1/VLC2, SEG2/VLC1 pin

The selection of SEG1/VLC2 pin function is controlled with the

bit 2 of register L2.

The selection of SEG2/VLC1 pin function is controlled with the

bit 1 of register L2.

When the VLC2 pin and VLC1 pin functions are selected and the

internal dividing resistor is not used, apply voltage of 0 < VLC1 <

VLC2 < VLC3 to these pins. Short the VLC2 pin and VLC1 pin at

1/2 bias.

When the VLC2 pin and VLC1 pin functions are selected and the

internal dividing resistor is used, the dividing voltage value

generated internally is output from the VLC1 pin and VLC2 pin.

The VLC2 pin and VLC1 pin have the same electric potential at

1/2 bias.

When SEG1 and SEG2 pin functions are selected, use the

internal dividing resistor (L20 = ”0”). In this time, VLC2 and

VLC1 are connected to the generated dividing voltage.

Fig 47. LCD power supply circuit example (1/3 bias condition selected)

VSS

VLC3

VLC2

VLC1

VLC3

SEG1

SEG2

(b) Register L2 = (1000)2

VSS

VLC3

VLC2

VLC1

SEG1

SEG2

(a) Register L2 = (0000)2

VSS

VLC3

VLC2

VLC1

VLC3

(d) Register L2 = (1111)2

VSS

VLC3

VLC2

VLC1

VLC3

External power supply

SEG0

VLC2

VLC1

VLC2

VLC1

External power supply

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