SIC63616-(Rev. 1.0) NO. P36
3240-0412
VCHLMOD: LCD system voltage regulator heavy load protection On/Off register (FF03H•D3)
Enables heavy load protection function for the LCD system voltage regulator.
When "1" is written: On
When "0" is written: Off
Reading: Valid
By writing "1" to VCHLMOD, the LCD system voltage regulator enters heavy load protection mode to
minimize degradation in display quality when fluctuations in the supply voltage occurs due to driving a
heavy load. The heavy load protection function is effective when the OSC3 clock is used or the buzzer/
FOUT signal is being output. However, heavy load protection mode increases current consumption
compared with normal operation mode. Therefore, do not set heavy load protection mode unless it is
necessary.
At initial reset, this register is set to "0".
4.2.5 Programming notes
(1) When the power supply voltage booster/halver is turned on, the V
D2
output voltage requires about
1 msec to stabilize. Do not switch the power source for the voltage regulator (LCD system voltage
regulator) to V
D2
until the stabilization time has elapsed.
(2) HLON is prohibited from use, as it may cause malfunctions. Always be sure to set to "0".
(3) Do not set DBON to "1" (boost mode) and VCSEL to "1" (driving with V
D2
) if the supply voltage V
DD
exceeds 2.5 V, as it may cause damage of the IC.
(4) Current consumption increases in heavy load protection mode, therefore do not set heavy load pro-
tection mode with software if unnecessary.