ST7565S
The Voltage Regulator Circuit
The step-up voltage generated at VOUT outputs the LCD
driver voltage V5 through the voltage regulator circuit.
Because the ST7565S chips have an internal high-accuracy
voltage regulator with a 64-level electronic volume control
and internal resistors for the V5 voltage regulator, systems
can be constructed without having to include high-accuracy
voltage regulator circuit components.
Note:
* The internal VREG thermal gradient is approximate -0.05%/°C.
* VDD is 0V unless otherwise specified.
(A) When the V5 Voltage Regulator Internal Resistors Are Used
Through the use of the V5 voltage regulator internal resistors
and the electronic volume function the liquid crystal power
supply voltage V5 can be controlled by commands alone
(without adding any external resistors), making it possible to
adjust the liquid crystal display brightness. The V5 voltage
can be calculated using equation A-1 over the range where:
| V5 | < | VOUT |.
Rb
V
5
= 1 +
V
EV
( )
Ra
Rb
α
162
= 1 +
1 -
V
REG
( ) ( )
Ra
α
162
∵ VEV
=
1 -
V
[ ( ) ]
REG
V
DD
V
EV(constant voltage supply+electronic volume)
Internal Ra
Internal Rb
V
5
Figure 8
Ver 0.6c
33/72
2009/09/07
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
