ST7093

Ver 2.1

2003/09/23

Electronic contrast control (32 steps)

Electronic contrast control data bits is 10H = (C4, C3, C2, C1, C0 ), Voltage regulation is adjusted as 32-contrast

step According to the value of Electronic contrast control data bits. LCD drive voltage V0 has one of 32 voltage

values if 5-bit data is set to the electronic contrast control register (ICONRAM address 10H). When using the

electronic contrast control function, you need to turn the voltage regulators on using power control instruction.

When REF is “Low”

V0 = ( 1 + Rb / Ra ) x Ven ….. (3)

Ven = Vref - nα

( n = 0, 1, 2, ….. 30, 31 )

α = Vref / 150

When REF is “High”

V0 = ( 1 + Rb / Ra ) x Ven ….. (4)

Ven = Vext - nα

( n = 0, 1, 2, ….. 30, 31 )

α = Vext / 150

No. C7 C6 C5 C4 C3 C2 C1 C0

n

V0

Contrast

1

-

-

- 0

0

0

0 0

0 (default)

Maximum

High

2

-

-

-

0

0

0

0

1

1

.

.

3

-

-

-

0

0

0

1

0

2

.

.

4

-

-

-

0

0

0

1

1

3

.

.

.

.

.

.

.

.

.

.

.

.

.

.

31

-

-

-

1

1

1

1

0

30

.

.

32

-

-

- 1

1

1

1

1

31

Minimum

Low

Electronic contrast control register

(“-“ don’t care)

+

-

REF

Vo

Vout

VR

VEXT

Vss

Vref

Inside Chip

Ra

GND

Rb

+

Ven

-

-

+

Electronic contrast control circuit