Heavy Load Protection Function - Epson S1C63616 Technical Manual

Table 4.2.2.1 lists settings of the above registers according to the supply voltage V
Table 4.2.2.1 Power control register settings according to supply voltage V
When V reference LCD drive power option is selected
C2
Power supply
DBON HLON
voltage V
DD
1.6 to 2.5 V 1
2.5 to 5.5 V 0
When V reference LCD drive power option is selected
C1
Power supply
DBON HLON
voltage V
DD
1.6 to 5.5 V 0

4.2.3 Heavy load protection function

In order to ensure a stable circuit behavior and LCD display quality even if the power supply voltage
fluctuates due to driving an external load, the internal operating voltage regulator and the LCD system
voltage regulator have a heavy load protection function.
The internal operating voltage regulator enters heavy load protection mode by writing "1" to the
VDHLMOD register and it ensures stable V
load such as a lamp or buzzer is driven with a port output.
The LCD system voltage regulator enters heavy load protection mode by writing "1" to the VCHLMOD
register and it ensures stable V
display has inconsistencies in density.
Note: Current consumption increases in heavy load protection mode, therefore do not set heavy load
protection mode with software if unnecessary.
4.2.4 I/O memory for power control
Table 4.2.4.1 shows the I/O address and the control bits for power control.
Register
Address
D3 D2 D1
VDSEL VCSEL HLON
FF02H
R/W
VCHLMOD VDHLMOD General LPWR
FF03H
R/W
*1 Initial value at initial reset
*2 Not set in the circuit
DBON: Power supply voltage booster/halver boost mode On/Off register (FF02H•D0)
Activates the power supply voltage booster/halver in boost mode.
When "1" is written: Booster On
When "0" is written: Booster Off
Reading: Valid
When "1" is written to DBON, the power supply voltage booster/halver activates in boost mode and almost
doubles the V voltage to generate the V
DD
when driving the LCD system voltage regulator with V
"0" is written to DBON, the voltage boost operation is deactivated. Be sure to set DBON to "0" (Off) when
driving the LCD system voltage regulator with V
At initial reset, this register is set to "0".
VDSEL VCSEL
oscillation system voltage regulators
0 0 1
0 0 0
VDSEL VCSEL
oscillation system voltage regulators
0 0 0
output. Use the heavy load protection function when a heavy
D1
–V outputs. Use the heavy load protection function when the LCD
C1 C5
Table 4.2.4.1 Power control bits
∗1
D0 Name Init
VDSEL 0
DBON
VCSEL 0
HLON 0
DBON 0
VCHLMOD 0
VDHLMOD 0
General 0
LPWR 0
voltage. Turn the power supply voltage booster/halver on
D2
Power source for internal and
V
DD
V
DD
Power source for internal and
V
DD
1 0
1 0
General-purpose register
V V Power source select for LCD system voltage regulator
D2 DD
On Off
Power voltage booster/halver halving mode On/Off
On Off Power voltage booster/halver boost mode On/Off
On Off
Heavy load protection mode On/Off for LCD system voltage regulator
On Off Heavy load protection mode On/Off for internal voltage regulator
1 0 General-purpose register
On Off
LCD system voltage regulator On/Off
*3 Constantly "0" when being read
(V reference voltage, V
D2 C2
. Furthermore, do not set both DBON and HLON to "1".
DD
SIC63616-(Rev. 1.0) NO. P34
.
DD
DD
Power source for LCD system
voltage regulator (V reference)
C2
× 2)
V (≈ V
D2 DD
V
DD
Power source for LCD system
voltage regulator (V reference)
C1
V
DD
Comment
= 1.6 to 2.5 V). When
DD
3240-0412